WorldWideScience

Sample records for aspheric acrysof sn60wf

  1. Comparison between OPD-scan results and contrast sensitivity of three intraocular lenses: spheric AcrySof SN60AT, aspheric AcrySof SN60WF and multifocal AcrySof Restor lens Estudo comparativo da análise de frente de onda e sensibilidade ao contraste entre as lentes intra-oculares multifocal AcrySof Restor SN60D3, monofocal AcrySof SN60WF asférica e a monofocal SN60AT esférica

    Directory of Open Access Journals (Sweden)

    Celso Takashi Nakano

    2009-08-01

    Full Text Available Purpose: Compare the OPD-scan results and the contrast sensitivity in patients who had implantation of the AcrySof SN60D3 multifocal IOL, the AcrySof SA60AT spheric monofocal IOL and the AcrySof SN60AT aspheric monofocal IOL. Methods: Thirty-two eyes received the multifocal IOL, 32 eyes received the spheric monofocal IOL and 32 eyes received the aspheric monofocal IOL. They were closely paired in age, sex, pre-operative wavefront analysis and contrast sensitivity. All patients was tested with the OPD-scan aberrometer, ETDRS chart at 100% and 9% contrasts and contrast sensitivity. Results: Statistically significant differences were detected more total aberration in SN60AT group (KW = 9.42; p=0.009 when compared to SN60D3 group (p=0.016 and SN60WF group (p=0.0047. The SN60AT group (KW = 16.20; p=0.0003 showed with high spherical aberration values compared to the SN60WF (p=0.00046 and SN60D3 (p=0.0014 group. No significant differences were found between groups in far-distance VA measured using ETDRS at 100% and 9% contrast. The SN60D3 group compared to SN60AT group (p=0.016 had low contrast sensitivity (log units with statistical difference in 6.0 cpd (KW = 7.84; p=0.0199, but no statistical difference between SN60WF and SN60AT group (p=0.91 and SN60WF and SN60D3 group (p=0.051. The SN60D3 group had low contrast sensitivity performed under mesopic conditions (KW = 10.79; p=0,0045 in 6cpd spatial frequency compared to the SN60AT group (p=0.011 and to the SN60WF group (p=0.007 with statistical significant differences. Conclusion: In all analyzed parameters of OPD-scan aberrometry the aspheric and the multifocal IOLs provided less total and spherical aberrations than spheric IOLs. All IOLs provided an excellent high and low contrasts vision, the multifocal IOL was as good as the spheric and aspheric monofocal IOLs.Objetivo: Comparar a sensibilidade ao contraste e análise de "wavefront" com OPD-scan em pacientes submetidos a cirurgia de facoemulsifica

  2. Change in corneal aberrations after cataract surgery with 2 types of aspherical intraocular lenses.

    Science.gov (United States)

    Marcos, Susana; Rosales, Patricia; Llorente, Lourdes; Jiménez-Alfaro, Ignacio

    2007-02-01

    To study the effect of cataract surgery through 3.2 mm superior incisions on corneal aberrations with 2 types of monofocal intraocular lenses (IOLs) with an aspherical design. Instituto de Optica, Consejo Superior de Investigaciones Científicas, and Fundación Jiménez Díaz, Madrid, Spain. Corneal topography of 43 eyes was obtained before and after small corneal incision cataract surgery. Twenty-two eyes had implantation of a Tecnis Z9000 silicone IOL (Advanced Medical Optics) and 21 had implantation of an AcrySof IQ SN60WF acrylic IOL (Alcon Research Labs) using the recommended injector for each IOL type. The intended incision size (3.2 mm) was similar in the 2 groups. Corneal aberrations were estimated using custom-developed algorithms (based on ray tracing) for 10.0 mm and 5.0 mm pupils. Comparisons between preoperative and postoperative measurements and across the groups were made for individual Zernike terms and root-mean-square (RMS) wavefront error. The RMS (excluding tilt and defocus) did not change in the AcrySof IQ group and increased significantly in the Tecnis group with the 10.0 mm and 5.0 mm pupil diameters. Spherical aberration and coma-like terms did not change significantly; however, vertical astigmatism, vertical trefoil, and vertical tetrafoil changed significantly with surgery with the 10.0 mm and 5.0 mm pupil diameters (Porder aberrations consistently showed a superior lobe, resulting from a combination of positive vertical trefoil (Z(3)(-3)) and negative tetrafoil (Z(4)(4)). The mean vertical astigmatism increased by 2.47 microm +/- 1.49 (SD) and 1.74 +/- 1.44 microm, vertical trefoil increased by 1.81 +/- 1.19 microm and 1.20 +/- 1.34 microm, and tetrafoil increased by -1.10 +/- 0.78 microm and -0.89 +/- 0.68 microm in the Tecnis group and AcrySof IQ group, respectively. There were no significant differences between the corneal aberrations in the 2 postoperative groups, although there was a tendency toward more terms or orders changing

  3. Aspherical supernovae

    International Nuclear Information System (INIS)

    Kasen, Daniel Nathan

    2004-01-01

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3) And

  4. Comparison of visual function and patient satisfaction with AcrySof ReSTORSN6AD1 multifocal intraocular compared to monofocal intraocular lenses 5

    Directory of Open Access Journals (Sweden)

    Aisa S Alchinova

    2016-12-01

    Full Text Available Aim. To compare visual function and satisfaction in patients after implantation of AcrySof ReSTOR SN6AD1 multifocal intraocular lens (IOL, AcrySof SA60AТ spherical monofocal IOL, or Akreos АО aspheric monofocal IOL during cataract surgery. Materials. Overall, 34 patients received SN6AD1 multifocal (group 1, 48 eyes, 19 patients received Akreos АО monofocal aspheric (group 2, 30 eyes, and 13 patients received AcrySof SA60AТ monofocal spherical (group 3, 18 eyes IOL. Patients with multifocal IOL were closely matched for age, sex, and ocular findings with patients who had monofocal IOL implantation. Six months postoperatively, uncorrected/corrected distance visual acuity (UDVA/CDVA, uncorrected intermediate (60 cm and near (35 cm visual acuity (UNVA, defocus curve, contrast sensitivity, and a quality-of-life questionnaire were evaluated. Furthermore, independence from glasses and presence of optical phenomena were assessed. Results. Patients in group 2 had statistically significant increase in UDVA than that in group 1 (p = 0.037. There was no significant difference in the mean uncorrected intermediate and best corrected distance visual acuities between the groups. UNVA was better in group 1 than that in groups 2 and 3 (p < 0.0001. Photopic contrast sensitivity for high spatial frequencies was better in groups 2 and 3. Glare was reported in 5.9% of patients in group 1. Halos occurred in 32.4% of patients in group 1. No one reported undesirable visual symptoms in groups 2 and 3. Conclusion. Multifocal IOLs provided higher spectacle independence and satisfactory functional vision over a broad range of distances but were associated with increased subjective visual symptoms and reduced photopic contrast sensitivity for high spatial frequencies and distance visual quality compared with monofocal IOLs.

  5. Contrast visual acuity after multifocal intraocular lens implantation:aspheric versus spherical design

    Directory of Open Access Journals (Sweden)

    Jun-Hua Li

    2014-02-01

    Full Text Available AIM: To evaluate contrast visual acuity (CVA after implantation of an aspheric apodized diffractive intraocular lens (IOL or a spherical apodized diffractive IOL in cataract surgery.METHOD: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL (30 eyes and a spherical AcrySof ReSTOR SN60D3 IOL (30 eyes. CVA with best distance correction was measured at 4 contrast levels (100%, 25%, 10% and 5% under 3 levels of chart luminance [250, 85 and 25 candelas per square meter (cd/m2] using a multi-functional visual acuity tester (MFVA-100.RESULTS:At 12 months after surgery, there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m2 (P100%=0.875 and P25%=0.057 and 85cd/m2 (P100%=0.198 and P25%=0.193 between the aspheric group and the spherical group. However, the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m2 (P10%=0.042 and P5%=0.007 and 85cd/m2 (P10%=0.002 and P5%=0.039. Under the luminance level of 25cd/m2, no significant differences was found in the 100% CVA between the 2 group (P100%=0.245, while aspheric group had better visual acuity in the remaining 3 contracts (P25%=0.023, P10%=0.026 and P5%=0.002, respectively.CONCULSION:The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.Keyword:cataract surgery; intraocular lens; contrast sensitivity; visual acuity

  6. Contrast sensitivity after refractive lens exchange with a multifocal diffractive aspheric intraocular lens

    Directory of Open Access Journals (Sweden)

    Teresa Ferrer-Blasco

    2013-04-01

    Full Text Available PURPOSE: To evaluate distance and near contrast sensitivity (CS under photopic and mesopic conditions before and after refractive lens exchange (RLE and implantation of the aspheric AcrySof®ReSTOR® (SN6AD3 model intraocular lens (IOL. METHODS:Seventy-four eyes of 37 patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patient sample was divided into myopic and hyperopic groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respectively were measured before and 6 months postoperatively. Monocular CS function was measured at three different luminance levels (85, 5 and 2.5 cd/m² before and after RLE. Post-implantation results at 6 months were compared with those found before surgery. RESULTS: Our results revealed that patients in both groups obtained good UCVA and BCVA after RLE at distance and near vision in relation to pre-surgery values. No statistically significant differences were found between the values of CS pre and post-RLE at distance and near, at any lighting condition and spatial frequency (p>0.002. CONCLUSIONS: Refractive lens exchange with aspheric AcrySof ReSTOR IOL in myopic and hyperopic population provided good visual function and yield good distance and near CS under photopic and mesopic conditions.

  7. Evaluation of Optical Quality: Ocular Scattering and Aberrations in Eyes Implanted with Diffractive Multifocal or Monofocal Intraocular Lenses.

    Science.gov (United States)

    Liao, Xuan; Lin, Jia; Tian, Jing; Wen, BaiWei; Tan, QingQing; Lan, ChangJun

    2018-06-01

    To compare objective optical quality, ocular scattering and aberrations of eyes implanted with an aspheric monofocal intraocular lens (IOL) or an aspheric apodized diffractive multifocal IOL three months after surgery. Prospective consecutive nonrandomized comparative cohort study. A total of 80 eyes from 57 cataract patients were bilaterally or unilaterally implanted with monofocal (AcrySof IQ SN60WF) or multifocal (AcrySof IQ ReSTOR SN6AD1) IOLs. Respectively, 40 eyes of 27 patients were implanted with monofocal IOLs, and 40 eyes of 30 patients were implanted with multifocal IOLs. Ocular high-order aberration (HOA) values were obtained using Hartmann-Shack aberrometer; objective scatter index (OSI), modulation transfer function (MTF) cutoff, Strehl ratio (SR), and contrast visual acuity OV at 100%, 20%, and 9% were measured using Objective Quality Analysis System II (OQAS II). Ocular aberrations performed similar in both groups (p > 0.05). However, significantly higher values of OSI and lower values of MTF cutoff, SR and OV were found in the SN6AD1 group (p < 0.05). Both ocular scattering and wave-front aberrations play essential role in retinal image quality, which may be overestimated when only aberrations were taken into account. Combining the effect of ocular scattering with HOA will result in a more accurate assessment of the visual and optical quality.

  8. Surface characterization protocol for precision aspheric optics

    Science.gov (United States)

    Sarepaka, RamaGopal V.; Sakthibalan, Siva; Doodala, Somaiah; Panwar, Rakesh S.; Kotaria, Rajendra

    2017-10-01

    In Advanced Optical Instrumentation, Aspherics provide an effective performance alternative. The aspheric fabrication and surface metrology, followed by aspheric design are complementary iterative processes for Precision Aspheric development. As in fabrication, a holistic approach of aspheric surface characterization is adopted to evaluate actual surface error and to aim at the deliverance of aspheric optics with desired surface quality. Precision optical surfaces are characterized by profilometry or by interferometry. Aspheric profiles are characterized by contact profilometers, through linear surface scans to analyze their Form, Figure and Finish errors. One must ensure that, the surface characterization procedure does not add to the resident profile errors (generated during the aspheric surface fabrication). This presentation examines the errors introduced post-surface generation and during profilometry of aspheric profiles. This effort is to identify sources of errors and is to optimize the metrology process. The sources of error during profilometry may be due to: profilometer settings, work-piece placement on the profilometer stage, selection of zenith/nadir points of aspheric profiles, metrology protocols, clear aperture - diameter analysis, computational limitations of the profiler and the software issues etc. At OPTICA, a PGI 1200 FTS contact profilometer (Taylor-Hobson make) is used for this study. Precision Optics of various profiles are studied, with due attention to possible sources of errors during characterization, with multi-directional scan approach for uniformity and repeatability of error estimation. This study provides an insight of aspheric surface characterization and helps in optimal aspheric surface production methodology.

  9. Influence of corneal asphericity on the refractive outcome of intraocular lens implantation in cataract surgery.

    Science.gov (United States)

    Savini, Giacomo; Hoffer, Kenneth J; Barboni, Piero

    2015-04-01

    To evaluate the possible influence of anterior corneal surface asphericity on the refractive outcomes in eyes having intraocular lens (IOL) implantation after cataract surgery. Fondazione G.B. Bietti IRCCS, Rome, Italy. Retrospective comparative case series. Intraocular lens power was calculated using the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Asphericity (Q-value) was measured at 8.0 mm with a Placido-disk corneal topographer (Keratron), a rotating Scheimpflug camera (Pentacam), and a rotating Scheimpflug camera combined with Placido-disk corneal topography (Sirius). The relationship between the error in refraction prediction (ie, difference between expected refraction and refraction measured 1 month after surgery) and the Q-value was assessed by linear regression. The same IOL model (Acrysof SA60AT) was implanted in 115 eyes of 115 consecutive patients. Regression analysis showed a statistically significant relationship between the error in refraction prediction and the Q-value with all formulas and all devices. In all cases, a more negative Q-value (prolate cornea) was associated with a myopic outcome, whereas a more positive Q-value (oblate cornea) was associated with a hyperopic outcome. The highest coefficient of determination was detected between the Hoffer Q formula and the Placido-disk corneal topographer (R(2) = 0.2630), for which the error in refraction prediction (y) was related to the Q-value (x) according to the formula y = -0.2641 + 1.4589 × x. Corneal asphericity influences the refractive outcomes of IOL implantation and should be taken into consideration when using third-generation IOL power formulas. Dr. Hoffer receives book royalties from Slack, Inc., Thorofare, New Jersey, and formula royalties from all manufacturers using the Hoffer Q formula. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  10. LIO pseudofácica suplementar sulcoflex® toric sobre LIO acrysof® toric

    Directory of Open Access Journals (Sweden)

    Hilton Arcoverde Gonçalves de Medeiros

    2013-10-01

    Full Text Available Para correção de alta hipermetropia e astigmatismo irregular secundário a múltiplas cirurgias refrativas em uma mulher de 45 anos, foi utilizada a sutura das incisões radiais, com implante de lente intraocular (LIO Acrysof® Toric. Para correção do residual de erro refracional, foi implantada LIO pseudofácica tórica suplementar sobre LIO Primária. A acuidade visual (AV inicial era de LogMAR 0,9 e a final de LogMAR 0,3. O implante da LIO suplementar tórica sobre LIO tórica primária mostrou-se uma boa opção, proporcionando melhora da acuidade visual.

  11. Injective Labeled Oriented Trees are Aspherical

    OpenAIRE

    Harlander, Jens; Rosebrock, Stephan

    2012-01-01

    A labeled oriented tree is called injective if each generator occurs at most once as an edge label. We show that injective labeled oriented trees are aspherical. The proof relies on a new relative asphericity test based on a lemma of Stallings.

  12. Lathe converted for grinding aspheric surfaces

    Science.gov (United States)

    Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

    1964-01-01

    A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

  13. Does the apodized diffractive intraocular lens Acrysof ReSTOR NaturalTM interfere with FDT Matrix perimetry results? A lente difrativa apodizada Acrysof ReSTOR NaturalTM pode interferir nos resultados da perimetria por FDT Matrix?

    Directory of Open Access Journals (Sweden)

    Karine Duarte Bojikian

    2009-12-01

    Full Text Available PURPOSE: To compare the effect of an apodized diffractive intraocular lens (IOL (Acrysof ReSTOR NaturalTM and its yellow counterpart (Natural IQ TM on frequency doubling technology (FDT perimetry results. METHODS: This study included 37 eyes from 22 patients at the "Centro Oftalmológico Tranjan" who had undergone uncomplicated phacoemulsification and intraocular lens implantation (17 Acrysof ReSTOR NaturalTM, 20 Natural IQ TM performed by the same surgeon, at least three months prior to the study. Patients were subject to frequency doubling technology Matrix Perimeter testing. RESULTS: The patients were between 41 to 79 years old (mean, 70.78 ± 9.83 in the Natural IQ TM and 49 to 81 years old (mean, 67.11± 11.48 in the Acrysof ReSTOR NaturalTM group, and the mean IOP was 13.64 ± 2.02 mmHg in the Natural IQ TM 12.94 ± 1.39 mmHg in the Acrysof ReSTOR NaturalTM group. The mean pupillary diameter under scotopic conditions was 6.63 ± 1.16 mm in the Natural IQ TM group and 7.20 ± 1.8 mm in the Acrysof ReSTOR NaturalTM group (p=0.20. The mean deviation was -1.83 ± 3.46 dB in the Natural IQ TM group and -1.77 ± 3.94 dB in the Acrysof ReSTOR NaturalTM group (p=0.28. The pattern standard deviation was 3.49 ± 0.79 dB in the Natural IQ TM group and 3.20 ± 0.86 dB in the Acrysof ReSTOR NaturalTM group (p=0.27. CONCLUSION: There was no difference in the results of FDT Matrix perimetry in eyes that received apodized diffractive IOLs implant or eyes that received monofocal intraocular lens implant.OBJETIVO: Comparar o efeito da lente difrativa apodizada (Acrysof ReSTOR NaturalTM e da lente de mesma plataforma amarela (Natural IQ TM sobre os resultados da perimetria de dupla frequência (FDT. MÉTODOS: O estudo incluiu 37 olhos de 22 pacientes do Centro Oftalmológico Tranjan que foram submetidos a cirurgia de facoemulsificação e implante de lentes intraoculares (17 Acrysof ReSTOR NaturalTM, 20 Natural IQ TM sem complicações, realizadas pelo mesmo

  14. Aspheric lenses for terahertz imaging.

    Science.gov (United States)

    Lo, Yat Hei; Leonhardt, Rainer

    2008-09-29

    We present novel designs for aspheric lenses used in terahertz (THz) imaging. As different surfaces result in different beam shaping properties and in different losses from reflection and absorption, the resultant imaging resolution (i.e. the focal spot size) depends critically on the design approach. We evaluate the different lens designs using Kirchhoff's scalar diffraction theory, and test the predictions experimentally. We also show that our lenses can achieve sub-wavelength resolution. While our lens designs are tested with THz radiation, the design considerations are applicable also to other regions of the electro-magnetic spectrum.

  15. Aspheric surface measurement using capacitive probes

    Science.gov (United States)

    Tao, Xin; Yuan, Daocheng; Li, Shaobo

    2017-02-01

    With the application of aspheres in optical fields, high precision and high efficiency aspheric surface metrology becomes a hot research topic. We describe a novel method of non-contact measurement of aspheric surface with capacitive probe. Taking an eccentric spherical surface as the object of study, the averaging effect of capacitive probe measurement and the influence of tilting the capacitive probe on the measurement results are investigated. By comparing measurement results from simultaneous measurement of the capacitive probe and contact probe of roundness instrument, this paper indicates the feasibility of using capacitive probes to test aspheric surface and proposes the compensation method of measurement error caused by averaging effect and the tilting of the capacitive probe.

  16. Simulation of aspheric tolerance with polynomial fitting

    Science.gov (United States)

    Li, Jing; Cen, Zhaofeng; Li, Xiaotong

    2018-01-01

    The shape of the aspheric lens changes caused by machining errors, resulting in a change in the optical transfer function, which affects the image quality. At present, there is no universally recognized tolerance criterion standard for aspheric surface. To study the influence of aspheric tolerances on the optical transfer function, the tolerances of polynomial fitting are allocated on the aspheric surface, and the imaging simulation is carried out by optical imaging software. Analysis is based on a set of aspheric imaging system. The error is generated in the range of a certain PV value, and expressed as a form of Zernike polynomial, which is added to the aspheric surface as a tolerance term. Through optical software analysis, the MTF of optical system can be obtained and used as the main evaluation index. Evaluate whether the effect of the added error on the MTF of the system meets the requirements of the current PV value. Change the PV value and repeat the operation until the acceptable maximum allowable PV value is obtained. According to the actual processing technology, consider the error of various shapes, such as M type, W type, random type error. The new method will provide a certain development for the actual free surface processing technology the reference value.

  17. Verification of aspheric contact lens back surfaces.

    Science.gov (United States)

    Dietze, Holger H; Cox, Michael J; Douthwaite, William A

    2003-08-01

    To suggest a tolerance level for the degree of asphericity of aspheric rigid gas-permeable contact lenses and to find a simple method for its verification. Using existing tolerances for the vertex radius, tolerance limits for eccentricity and p values and were calculated. A keratometer-based method and a method based on sag measurements were used to measure the vertex radius and eccentricity of eight concave progressively aspheric surfaces and six concave ellipsoidal surfaces. The results were compared with a gold standard measurement made using a high-precision mechanical instrument (Form Talysurf). The suggested tolerance for eccentricity and p value and is +/-0.05. The keratometer method was very accurate and precise at measuring the vertex radius (mean deviation +/- SD from Talysurf results, -0.002 +/- 0.008 mm). The keratometer was more precise than and similar in accuracy to the sag method for measurement of asphericity (mean deviation of keratometer method results from Talysurf results, 0.017 +/- 0.018; mean deviation of sag method results from Talysurf results using five semichords, -0.016 +/- 0.032). Neither method was precise enough to verify the asphericity within the suggested tolerance. The keratometer can be efficiently used to verify the back vertex radius within its International Organization for Standardization tolerance and the back surface asphericity within an eccentricity/p value tolerance of +/-0.1. The method is poor for progressive aspheres with large edge blending zones. Deriving the eccentricity from sag measurements is a potential alternative if the mathematical description of the surface is known. The limiting factor of this method is the accuracy and precision of individual sag measurements.

  18. Construction, specification, and mathematical description of aspheric surfaces.

    Science.gov (United States)

    Smith, G; Atchison, D A

    1983-03-01

    Rotationally symmetrical aspheric surfaces of spectacle lenses are constructed as either "zonal aspherics" or "continuous aspherics." Zonal aspherics consist of annular zones surrounding a central zone with each zone being nominally spherical with progressively lower surface power the farther the zone is from the surface vertex. Aspheric surfaces are often specified by the radial drop in surface power from the center to the edge of the lens (e.g., Welsh Four-drop), but for assessment purposes the surface shape must be specified more precisely. The formulas for the description of continuous aspherics can be manipulated into different forms. Mathematical descriptions are given or developed which will enable theoretical assessment of the performances of all lenses with rotationally symmetrical aspheric surfaces.

  19. Aspherical bubble dynamics and oscillation times

    Energy Technology Data Exchange (ETDEWEB)

    Godwin, R.P.; Chapyak, E.J. [Los Alamos National Lab., NM (United States); Noack, J.; Vogel, A. [Medizinisches Laserzentrum Luebeck (Germany)

    1999-03-01

    The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored. Time-resolved experimental photographs and simulations of large aspect ratio (length:diameter {approximately}20) cylindrical bubble dynamics are presented. The experiments and calculations exhibit similar dynamics. A small high-pressure cylindrical bubble initially expands radially with hardly any axial motion. Then, after reaching its maximum volume, a cylindrical bubble collapses along its long axis with relatively little radial motion. The growth-collapse period of these very aspherical bubbles differs only sightly from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble energy even for aspherical bubbles. The prolongation of the oscillation period of bubbles near solid boundaries relative to that of isolated spherical bubbles is also discussed.

  20. Optimized method for manufacturing large aspheric surfaces

    Science.gov (United States)

    Zhou, Xusheng; Li, Shengyi; Dai, Yifan; Xie, Xuhui

    2007-12-01

    Aspheric optics are being used more and more widely in modern optical systems, due to their ability of correcting aberrations, enhancing image quality, enlarging the field of view and extending the range of effect, while reducing the weight and volume of the system. With optical technology development, we have more pressing requirement to large-aperture and high-precision aspheric surfaces. The original computer controlled optical surfacing (CCOS) technique cannot meet the challenge of precision and machining efficiency. This problem has been thought highly of by researchers. Aiming at the problem of original polishing process, an optimized method for manufacturing large aspheric surfaces is put forward. Subsurface damage (SSD), full aperture errors and full band of frequency errors are all in control of this method. Lesser SSD depth can be gained by using little hardness tool and small abrasive grains in grinding process. For full aperture errors control, edge effects can be controlled by using smaller tools and amendment model with material removal function. For full band of frequency errors control, low frequency errors can be corrected with the optimized material removal function, while medium-high frequency errors by using uniform removing principle. With this optimized method, the accuracy of a K9 glass paraboloid mirror can reach rms 0.055 waves (where a wave is 0.6328μm) in a short time. The results show that the optimized method can guide large aspheric surface manufacturing effectively.

  1. Aspheric surface testing by irradiance transport equation

    Science.gov (United States)

    Shomali, Ramin; Darudi, Ahmad; Nasiri, Sadollah; Asgharsharghi Bonab, Armir

    2010-10-01

    In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This subject is investigated by a simulation procedure.

  2. Modified alignment CGHs for aspheric surface test

    Science.gov (United States)

    Song, Jae-Bong; Yang, Ho-Soon; Rhee, Hyug-Gyo; Lee, Yun-Woo

    2009-08-01

    Computer Generated Holograms (CGH) for optical test are commonly consisted of one main pattern for testing aspheric surface and some alignment patterns for aligning the interferometer, CGH, and the test optics. To align the CGH plate and the test optics, we designed the alignment CGHs modified from the cat's eye alignment method, which are consisted of a couple of CGH patterns. The incident beam passed through the one part of the alignment CGH pattern is focused onto the one radius position of the test aspheric surface, and is reflected to the other part, and vice versa. This method has several merits compared to the conventional cat's eye alignment method. First, this method can be used in testing optics with a center hole, and the center part of CGH plate can be assigned to the alignment pattern. Second, the alignment pattern becomes a concentric circular arc pattern. The whole CGH patterns including the main pattern and alignment patterns are consisted of only concentric circular fringes. This concentric circular pattern can be easily made by the polar coordinated writer with circular scanning. The required diffraction angle becomes relatively small, so the 1st order diffraction beams instead of the 3rd order diffraction beam can be used as alignment beams, and the visibility can be improved. This alignment method also is more sensitive to the tilt and the lateral shift of the test aspheric surface. Using this alignment pattern, a 200 mm diameter F/0.5 aspheric mirror and a 600 mm diameter F/0.9 mirror were tested.

  3. An intuitive concept for manufacturing and inspecting of aspherical components

    Science.gov (United States)

    Chou, Hsiao-Yu; Chang, Keng-Shou

    2011-09-01

    In this paper we propose an intuitive concept for manufacturing and inspecting of aspherical components. Two types, parabolic and cylinder, of plano-convex and plano-concave aspherical lenses were made by LOH 120S form generation machine. Three form error measurement methods were used known as coordinate measuring machine (CMM), interferometer with CGH null lens and inspection with combined pair lenses. Ultra high accuracy CMM from Panasonic Co., CGH cylinder null and CGH aspheric null from Diffraction International and OWI 150 ASPH CGH interferometer from OptoTech GmbH play the roll for measurement. CMM was used as a surface profiler to inspect the surface shape, and the software GRAPHER was also used as analysis tool to exam asphere numerical datum. The difference between theoretical and practical is as a surface polishing revised reference. The finished plano-convex and plano-concave aspherical lenses can be combined to be a plane lens. The individual and combined lenses were inspected on OPTOTECH OWI 150 ASPH CGH interferometer. The compared interference patterns have shown with the Diffration International CGH Aspheric Null "ASPHERIC 1" and CGH Cylinder Null "H80F2C". Through the procedure, the combined plano-convex and plano-concave aspherical lenses should be a perfect match plane lens and the individual lens might be an aspherical test standard element for quick inspection.

  4. Comparação da análise da frente de onda e da sensibilidade ao contraste em olhos pseudofácicos com implante de lentes intra-oculares esférica e asférica Wavefront analysis and contrast sensitivity comparison between spheric and aspheric intraocular lenses

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2008-06-01

    Full Text Available OBJETIVO: Comparar a análise da frente de onda e a sensibilidade de contraste pós-operatórias em pacientes submetidos à facoemulsificação com implante de lentes intra-oculares esféricas num olho e asféricas no olho contralateral. MÉTODOS: Este estudo prospectivo comparativo, randomizado, duplo-cego, incluiu 32 olhos de 16 pacientes. Uma avaliação oftalmológica completa foi realizada durante as visitas antes e depois da cirurgia (no primeiro, terceiro, sétimo, e nonagésimo dias pós-cirúrgicos, que incluiu acuidade visual, teste de sensibilidade ao contraste, aberrometria. Todos exames (menos aberrometr=ia foram feitos monocularmente com pupilas não dilatadas. Os pacientes foram submetidos a facectomia ultra-sônica convencional com implante de uma lente asférica SN60WF num olho e esférica SN60ATno outro. RESULTADOS: A acuidade visual média com a melhor correção foi -0,146 LogMAR no grupo da lente intra-ocular esférica, e -0.165 logMAR no grupo da lente intra-ocular asférica sob condições fotópicas, -0,003 LogMAR sob condições mesópicas. A sensibilidade ao contraste foi semelhante em ambos os grupos tanto em condições fotópicas e mesópicas. Em relação às aberrações ópticas ocorreu uma diferença significativa nas aberrações totais (1,09 ± 0,56 no grupo asférico e 1,52 ± 1,19 no grupo esférico e no componente esférico das aberrações de alta ordem(0,422 ± 0,202 no grupo asférico e 0,124 ± 0,087 no grupo esférico. CONCLUSÃO: As duas lentes intra-oculares promoveram uma excelente visão em situações de alto contraste, e os olhos implantados com a lente asférica tiveram menos aberrações totais e esféricas que aqueles implantados com a lente esférica.PURPOSE: Compare the wavefront and contrast sensitivity of bilateral pseudophakic patients with aspheric in one eye and spheric intraocular lenses in the other. METHODS: This prospective, comparative, randomized study, double masked, included 32

  5. Precision production: enabling deterministic throughput for precision aspheres with MRF

    Science.gov (United States)

    Maloney, Chris; Entezarian, Navid; Dumas, Paul

    2017-10-01

    Aspherical lenses offer advantages over spherical optics by improving image quality or reducing the number of elements necessary in an optical system. Aspheres are no longer being used exclusively by high-end optical systems but are now replacing spherical optics in many applications. The need for a method of production-manufacturing of precision aspheres has emerged and is part of the reason that the optics industry is shifting away from artisan-based techniques towards more deterministic methods. Not only does Magnetorheological Finishing (MRF) empower deterministic figure correction for the most demanding aspheres but it also enables deterministic and efficient throughput for series production of aspheres. The Q-flex MRF platform is designed to support batch production in a simple and user friendly manner. Thorlabs routinely utilizes the advancements of this platform and has provided results from using MRF to finish a batch of aspheres as a case study. We have developed an analysis notebook to evaluate necessary specifications for implementing quality control metrics. MRF brings confidence to optical manufacturing by ensuring high throughput for batch processing of aspheres.

  6. Anterior corneal profile with variable asphericity.

    Science.gov (United States)

    Rosales, Marco A; Juárez-Aubry, Montserrat; López-Olazagasti, Estela; Ibarra, Jorge; Tepichín, Eduardo

    2009-12-10

    We present a corneal profile in which the eccentricity, e(Q=-e(2)), has a nonlinear continuous variation from the center outwards. This nonlinear variation is intended to fit and reproduce our current experimental data in which the anterior corneal surface of the human eye exhibits different values of e at different diameters. According to our clinical data, the variation is similar to an exponential decay. We propose a linear combination of two exponential functions to describe the variation of e. We then calculate the corneal sagittal height by substituting e in the first-order aspherical surface equation to obtain the corneal profile. This corneal profile will be used as a reference to analyze the resultant profiles of the customized corneal ablation in refractive surgery.

  7. Ion beam figuring of silicon aspheres

    Science.gov (United States)

    Demmler, Marcel; Zeuner, Michael; Luca, Alfonz; Dunger, Thoralf; Rost, Dirk; Kiontke, Sven; Krüger, Marcus

    2011-03-01

    Silicon lenses are widely used for infrared applications. Especially for portable devices the size and weight of the optical system are very important factors. The use of aspherical silicon lenses instead of spherical silicon lenses results in a significant reduction of weight and size. The manufacture of silicon lenses is more challenging than the manufacture of standard glass lenses. Typically conventional methods like diamond turning, grinding and polishing are used. However, due to the high hardness of silicon, diamond turning is very difficult and requires a lot of experience. To achieve surfaces of a high quality a polishing step is mandatory within the manufacturing process. Nevertheless, the required surface form accuracy cannot be achieved through the use of conventional polishing methods because of the unpredictable behavior of the polishing tools, which leads to an unstable removal rate. To overcome these disadvantages a method called Ion Beam Figuring can be used to manufacture silicon lenses with high surface form accuracies. The general advantage of the Ion Beam Figuring technology is a contactless polishing process without any aging effects of the tool. Due to this an excellent stability of the removal rate without any mechanical surface damage is achieved. The related physical process - called sputtering - can be applied to any material and is therefore also applicable to materials of high hardness like Silicon (SiC, WC). The process is realized through the commercially available ion beam figuring system IonScan 3D. During the process, the substrate is moved in front of a focused broad ion beam. The local milling rate is controlled via a modulated velocity profile, which is calculated specifically for each surface topology in order to mill the material at the associated positions to the target geometry. The authors will present aspherical silicon lenses with very high surface form accuracies compared to conventionally manufactured lenses.

  8. Stress analysis of aspherical coated particle with inner pressure

    Energy Technology Data Exchange (ETDEWEB)

    Liu Bing, E-mail: bingliu@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 (China); Yang Lin; Liang Tongxiang; Tang Chunhe [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 (China)

    2012-10-15

    Coated particles used in HTR fuel element sustain the inner pressure during irradiation as a pressure vessel. In actually the coated particle is not real spherical but with some asphericity, the stress distribution in the vessel is not uniform, coated layer in aspherical particle sustain more additional stress due to the asphericity. In this paper, the geometric shape distribution is summarized based on actual coated particle statistic. A mechanical analysis model is proposed for SiC layer by geometric combinations, and stress distribution of coated particle with a flat is calculated. The results show that the local maximum stress of aspherical particle increased two times than that of ideal spherical coated particle, which increase the failure probability under irradiation and high temperature.

  9. Aspherical Dust Envelopes Around Oxygen-Rich AGB Stars

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    2006-12-01

    Full Text Available We model the aspherical dust envelopes around O-rich AGB stars. We perform the radiative transfer model calculations for axisymmetric dust distributions. We simulate what could be observed from the aspherical dust envelopes around O-rich AGB stars by presenting the model spectral energy distributions and images at various wavelengths for different optical depths and viewing angles. The model results are very different from the ones with spherically symmetric geometry.

  10. ASPHERICAL SURFACES APPROXIMATION IN AUTOMATED DESIGN OF OPTICAL SYSTEMS

    Directory of Open Access Journals (Sweden)

    T. V. Ivanova

    2015-07-01

    Full Text Available Subject of Research. The paper deals with the problems of higher order aspherical surfaces approximation using different equation types. The objects of research are two types of equations for higher order aspherical surfaces description used in different software for optical systems design (SАRО, OPAL, ZEMAX, CODE-V, etc. and dependent on z-coordinate or on a radial coordinate on the surface. Conversion from one type of equations to another is considered in view of application in different software for optical systems design. Methods. The subject matter of the method lies in usage of mean square method approximation for recalculation of high-order aspherical surface. Iterative algorithm for recalculation is presented giving the possibility to recalculate coefficients for different types of equations with required accuracy. Recommendations are given for choosing recalculation parameters such as the number of result equation coefficients, the number of points for recalculation and point allocation on a surface. Main Results. Example of recalculation for aspherical surface and accuracy estimation, including result aberration comparison between initial surface and recalculated surface are presented. The example has shown that required accuracy of surface representation was obtained. Practical Relevance. This technique is usable for recalculation of higher order aspherical surfaces in various types of software for optical systems design and also for research of optimal higher order aspherical surfaces description.

  11. Measurement of high-departure aspheres using subaperture stitching with the Variable Optical Null (VON)

    Science.gov (United States)

    Kulawiec, Andrew; Murphy, Paul; DeMarco, Michael

    2010-10-01

    Aspheric surfaces are proven to provide significant benefits to a wide variety of optical systems, but the ability to produce high-precision aspheric surfaces has historically been limited by the ability (or lack thereof) to measure them. Traditionally, aspheric measurements have required dedicated null optics, but the cost, lead time, and calibration difficulty of using null optics has made the use of aspheres more challenging and less attractive. In the past three years, QED has developed the Subaperture Stitching Interferometer for Aspheres (SSI-A®) to help address this limitation, providing flexible aspheric measurement capability of up to 200 waves of aspheric departure from best-fit sphere. Some aspheres, however, have thousands of waves of departure. We have recently developed Variable Optical Null (VON) technology that can null much of the aspheric departure in a subaperture. The VON is automatically configurable and is adjusted to nearly null each specific subaperture of an asphere. This ability to nearly null a local subaperture of an asphere provides a significant boost in aspheric measurement capability, enabling aspheres with up to 1000 waves of departure to be measured, without the use of dedicated null optics. We outline the basic principles of subaperture stitching and VON technology, demonstrate the extended capability provided by the VON, and present measurement results from the new Aspheric Stitching Interferometer (ASI®).

  12. CUSTOM OPTIMIZATION OF INTRAOCULAR LENS ASPHERICITY

    Science.gov (United States)

    Koch, Douglas D.; Wang, Li

    2007-01-01

    Purpose To investigate the optimal amount of ocular spherical aberration (SA) in an intraocular lens (IOL) to maximize optical quality. Methods In 154 eyes of 94 patients aged 40 to 80 years, implantation of aspheric IOLs was simulated with different amounts of SA to produce residual ocular SA from −0.30 μm to +0.30 μm. Using the VOL-CT program (Sarver & Associates, Carbondale, Illinois), corneal wavefront aberrations up to 6th order were computed from corneal topographic elevation data (Humphrey Atlas, Carl Zeiss Meditec, Inc, Dublin, California). Using the ZernikeTool program (Advanced Medical Optics, Inc, Santa Ana, California), the polychromatic point spread function with Stiles-Crawford effect was calculated for the residual ocular higher-order aberrations (HOAs, 3rd to 6th order, 6-mm pupil), assuming fully corrected 2nd-order aberrations. Five parameters were used to quantify optical image quality, and we determined the residual ocular SA at which the maximal image quality was achieved for each eye. Stepwise multiple regression analysis was performed to assess the predictors for optimal SA of each eye. Results The optimal SA varied widely among eyes. Most eyes had best image quality with low amounts of negative SA. For modulation transfer function volume up to 15 cycles/degree, the amount of optimal SA could be predicted based on other HOAs of the cornea with coefficient of multiple determination (R2) of 79%. Eight Zernike terms significantly contributed to the optimal SA in this model; the order of importance to optimal SA from most to least was: Z60, Z62, Z42, Z53, Z64, Z3−1, Z33, and Z31. For the other 4 measures of visual quality, the coefficients of determination varied from 32% to 63%. Conclusion The amount of ocular SA producing best image quality varied widely among subjects and could be predicted based on corneal HOAs. Selection of an aspheric IOL should be customized according to the full spectrum of corneal HOAs and not 4th-order SA alone

  13. [Depth of focus in spherical and aspheric intraocular lenses].

    Science.gov (United States)

    Nan, Li; Tang, Xin; Liu, Yong-ji

    2012-02-01

    To investigate depth of focus (DOF) in spherical and aspheric IOL eye models. Computer numerical simulation experiment was used. IOL eye model based on Liou-Brennan eye model was constructed by using ZEMAX optical design software. Different IOL were implanted in this eye model. Monochromatic through focus modulation transfer function (MTF) curves were computed. Pupil and aspheric designs' effect on DOF were analyzed. DOF of eye model increased with pupil shrinkage in 550 nm monochromatic light (FY60AD 1.20 D at 6 mm pupil, 1.35 D at 5 mm pupil, 1.70 D at 4 mm pupil, 2.46 D at 3 mm pupil; YA60BBR 1.24 D at 6 mm pupil, 1.48 D at 5 mm pupil, 1.80 D at 4 mm pupil, 2.50 D at 3 mm pupil). MTF in spherical IOL eye model was higher with minus defocus, this trend was obvious at larger pupil. MTF of aspheric IOL eyes were higher than spherical IOL eyes when well focused at 5 mm pupil, while the DOF was lower in aspheric IOL with negative spherical aberration (Tecnis Z9000 1.31 D, FY60AD 1.35 D, CeeOn911 1.55 D, YA60BBR 1.48 D). DOF decreased less in aspheric IOL with zero spherical aberration (LI61AO 1.42 D). DOF in IOL eye model was higher at smaller pupil. When the pupil was large, well focused aspheric IOL improved optical quality compared with spherical IOL, while DOF and the tolerance to defocus in aspheric IOL were partially lost; this phenomenon was obvious with minus defocus.

  14. Asphere cross testing: an exercise in uncertainty estimation

    Science.gov (United States)

    Murphy, Paul E.

    2017-10-01

    Aspheric surfaces can provide substantial improvements to optical designs, but they can also be difficult to manufacture cost-effectively. Asphere metrology contributes significantly to this difficulty, especially for high-precision aspheric surfaces. With the advent of computer-controlled fabrication machinery, optical surface quality is chiefly limited by the ability to measure it. Consequently, understanding the uncertainty of surface measurements is of great importance for determining what optical surface quality can be achieved. We measured sample aspheres using multiple techniques: profilometry, null interferometry, and subaperture stitching. We also obtained repeatability and reproducibility (R&R) measurement data by retesting the same aspheres under various conditions. We highlight some of the details associated with the different measurement techniques, especially efforts to reduce bias in the null tests via calibration. We compare and contrast the measurement results, and obtain an empirical view of the measurement uncertainty of the different techniques. We found fair agreement in overall surface form among the methods, but meaningful differences in reproducibility and mid-spatial frequency performance.

  15. Theoretical fringe profiles with crossed Babinet compensators in testing concave aspheric surfaces.

    Science.gov (United States)

    Saxena, A K; Lancelot, J P

    1982-11-15

    This paper presents the theory for the use of crossed Babinet compensators in testing concave aspheric surfaces. Theoretical fringe profiles for a sphere and for an aspheric surface with primary aberration are shown. Advantages of this method are discussed.

  16. Desempenho visual dos pacientes pseudofácicos com diferentes lentes intraoculares

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2013-10-01

    Full Text Available OBJETIVO: Comparar a performance visual dos pacientes submetidos ao implante das lentes intraoculares multifocais difrativas Tecnis® MF ZM900, Acrysof® Restor® SN60D3, Acrysof® SN60WF e Acrysof® SN60AT. MÉTODOS: Estudo prospectivo comparativo, não randomizado, que incluiu 142 olhos de 71 pacientes com catarata, provenientes do ambulatório de oftalmologia do HC-FMUSP. A avaliação oftalmológica contou com medida da acuidade visual para longa, intermediária e curta distância, sem correção e com a melhor correção óptica, teste de sensibilidade ao contraste, pupilometria e análise de frente de onda por meio do aberrômetro. Todos os exames foram realizados com seis meses de pós-operatório. RESULTADOS: A média de idade dos pacientes foi de 60,7±6,6 anos no grupo Tecnis, 63,1±4,4 anos no grupo Restor e 63,7±4,2 anos no grupo monofocal (SN60AT no olho contralateral SN60WF. A acuidade visual para perto não corrigida e corrigida para longe foi estatisticamente superior nos grupos multifocal Restor e multifocal Tecnis em comparação ao grupo monofocal SN60AT/SN60WF (p<0,001. Não houve diferença estatística entre os grupos na comparação da acuidade visual para longe (p=0,56. A sensibilidade ao contraste fotópica monocular foi estatisticamente inferior nos grupos Restor e Tecnis (p<0,001. A SN60AT apresentou maior aberração esférica comparada a todas as outras lentes (p<0,001. A Tecnis se mostrou com menores valores médios de aberrações esféricas na comparação com a Restor (p<0.001. CONCLUSÃO: A Restor e Tecnis apresentaram melhor acuidade visual para perto do que o grupo monofocal SN60AT/SN60WF. Todas as lentes intraoculares promoveram boa visão para longe. O grupo da Tecnis apresentou melhor sensibilidade de contraste, menos aberrações ópticas e melhor visão intermediária que o grupo Restor.

  17. In vivo longitudinal chromatic aberration of pseudophakic eyes.

    Science.gov (United States)

    Siedlecki, Damian; Jóźwik, Agnieszka; Zając, Marek; Hill-Bator, Aneta; Turno-Kręcicka, Anna

    2014-02-01

    To present the results of longitudinal chromatic aberration measurements on two groups of pseudophakic eyes in comparison to healthy eyes. The longitudinal chromatic aberration of the eye, defined as chromatic difference of refraction with disabled accommodation, was measured with the use of a visual refractometer with a custom-designed target illuminator consisting of a narrow-band RGB diode (blue λb = 470 ± 15 nm; green λg = 525 ± 18 nm; red λr = 660 ± 10 nm). The measurements were performed on nine eyes implanted with AcrySof IQ SN60WF, 14 eyes implanted with AcrySof SA60AT, and 10 phakic eyes under cycloplegia. The mean values of the longitudinal chromatic aberration between 470 and 660 nm for the control group was 1.12 ± 0.14 D. For SA60AT group, it was 1.45 ± 0.42 D whereas for SN60WF it was 1.17 ± 0.52 D. The statistical test showed significant difference between SA60AT and the control group (p chromatic aberration in vivo can be easily and reliably estimated with an adapted visual refractometer. The two groups of pseudophakic eyes measured in this study showed different values of chromatic aberration. Its magnitude for SA60AT group was significantly larger than for the control group whereas for SN60WF the difference was not significant. The optical material used for intraocular lens design may have significant influence on the magnitude of the chromatic aberration of the pseudophakic eye, and therefore on its optical and visual performance in polychromatic light.

  18. Comparison of asphere measurements by tactile and optical metrological instruments

    NARCIS (Netherlands)

    Bergmans, R.H.; Nieuwenkamp, H.J.; Kok, G.J.P.; Blobel, G.; Nouira, H.; Küng, A.; Baas, M.; Voert, M.J.A. te; Baer, G.; Stuerwald, S.

    2015-01-01

    A comparison of topography measurements of aspherical surfaces was carried out by European metrology institutes, other research institutes and a company as part of an European metrology research project. In this paper the results of this comparison are presented. Two artefacts were circulated, a

  19. Computer numeric control subaperture aspheric surface polishing—microroughness evaluation

    Czech Academy of Sciences Publication Activity Database

    Procháska, František; Polák, Jaroslav; Matoušek, O.; Tomka, David

    2014-01-01

    Roč. 53, č. 9 (2014), 092011-092011 ISSN 0091-3286 R&D Projects: GA MŠk(CZ) ED2.1.00/03.0079 Institutional support: RVO:61389021 Keywords : aspheric polishing * optic surface microroughness evaluation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.954, year: 2014 http://opticalengineering.spiedigitallibrary.org/article.aspx?articleid=1901511

  20. Quantitative test for concave aspheric surfaces using a Babinet compensator.

    Science.gov (United States)

    Saxena, A K

    1979-08-15

    A quantitative test for the evaluation of surface figures of concave aspheric surfaces using a Babinet compensator is reported. A theoretical estimate of the sensitivity is 0.002lambda for a minimum detectable phase change of 2 pi x 10(-3) rad over a segment length of 1.0 cm.

  1. Surface topography of parallel grinding process for nonaxisymmetric aspheric lens

    International Nuclear Information System (INIS)

    Zhang Ningning; Wang Zhenzhong; Pan Ri; Wang Chunjin; Guo Yinbiao

    2012-01-01

    Workpiece surface profile, texture and roughness can be predicted by modeling the topography of wheel surface and modeling kinematics of grinding process, which compose an important part of precision grinding process theory. Parallel grinding technology is an important method for nonaxisymmetric aspheric lens machining, but there is few report on relevant simulation. In this paper, a simulation method based on parallel grinding for precision machining of aspheric lens is proposed. The method combines modeling the random surface of wheel and modeling the single grain track based on arc wheel contact points. Then, a mathematical algorithm for surface topography is proposed and applied in conditions of different machining parameters. The consistence between the results of simulation and test proves that the algorithm is correct and efficient. (authors)

  2. Optical description and design method with annularly stitched aspheric surface.

    Science.gov (United States)

    Cheng, De-Wen; Chen, Xue-Jiao; Xu, Chen; Hu, Yuan; Wang, Yong-Tian

    2015-12-01

    The relentless pressure for designs with new optical functions, small volume, and light weight has greatly increased the importance of aspheric surfaces. In this paper, we propose an annularly stitched aspheric surface (ASAS) description method to increase the freedom and flexibility of imaging system design. The rotationally symmetric ASAS consists of a circular central zone and one or more annular zones. Two neighboring zones are constrained to have the same derivatives on their joint curve, and this means the ASAS is C1 continuous. This finding is proved and verified by the mathematical deduction of the surface formulas. Two optimization strategies and two design methods with the C1 continuous constraints are also discussed. This surface can greatly facilitate the design and even achieve some previously impossible designs without increasing the fabrication difficulty. Two different systems with the proposed ASAS are optimized and the results are presented. The design results verified the practicability of the ASAS.

  3. Incoherently combining logarithmic aspheric lenses for extended depth of field.

    Science.gov (United States)

    Chu, Kaiqin; George, Nicholas; Chi, Wanli

    2009-10-01

    We describe a method for combining concentric logarithmic aspheric lenses in order to obtain an extended depth of field. Substantial improvement in extending the depth of field is obtained by carefully controlling the optical path difference among the concentric lenses so that their outputs combine incoherently. The system is analyzed through diffraction theory and the point spread function is shown to be highly invariant over a long range of object distances. After testing the image performance on a three-dimensional scene, we found that the incoherently combined logarithmic aspheres can provide a high-quality image over an axial distance corresponding to a defocus of +/- 14(lambda/4). Studies of the images of two-point objects are presented to illustrate the resolution of these lenses.

  4. Combining zonal refractive and diffractive aspheric multifocal intraocular lenses.

    Science.gov (United States)

    Muñoz, Gonzalo; Albarrán-Diego, César; Javaloy, Jaime; Sakla, Hani F; Cerviño, Alejandro

    2012-03-01

    To assess visual performance with the combination of a zonal refractive aspheric multifocal intraocular lens (MIOL) (Lentis Mplus, Oculentis GmbH) and a diffractive aspheric MIOL (Acri.Lisa 366, Acri.Tech GmbH). This prospective interventional cohort study comprised 80 eyes from 40 cataract patients (mean age: 65.5±7.3 years) who underwent implantation of the Lentis Mplus MIOL in one eye and Acri.Lisa 366 MIOL in the fellow eye. The main outcome measures were refraction; monocular and binocular uncorrected and corrected distance, intermediate, and near visual acuities; monocular and binocular defocus curves; binocular photopic contrast sensitivity function compared to a monofocal intraocular lens (IOL) control group (40 age-matched pseudophakic patients implanted with the AR-40e [Abbott Medical Optics]); and quality of vision questionnaire. Binocular uncorrected visual acuities were 0.12 logMAR (0.76 decimal) or better at all distances measured between 6 m and 33 cm. The Lentis Mplus provided statistically significant better vision than the Acri.Lisa at distances between 2 m and 40 cm, and the Acri.Lisa provided statistically significant better vision than the Lentis Mplus at 33 cm. Binocular defocus curve showed little drop-off at intermediate distances. Photopic contrast sensitivity function for distance and near were similar to the monofocal IOL control group except for higher frequencies. Moderate glare (15%), night vision problems (12.5%), and halos (10%) were reported. Complete independence of spectacles was achieved by 92.5% of patients. The combination of zonal refractive aspheric and diffractive aspheric MIOLs resulted in excellent uncorrected binocular distance, intermediate, and near vision, with low incidence of significant photic phenomena and high patient satisfaction. Copyright 2012, SLACK Incorporated.

  5. Some aspects of powerful lasers and aspheric lenses design

    International Nuclear Information System (INIS)

    Metz, Jean de

    1976-01-01

    Gigawatt power glass lasers are described. Geometrical, interferometric, coherence and focusing aspects of the beam are measured. Design of disc amplifier is shown with high gain glass. Aspheric lenses are designed and tested for focussing these beams. Experiments of multi-breakdown in gas are done. We get fusion in plasma made by second harmonic frequency of our 1.06 μ beam. Effect of self-focussing on laser beam quality is studied. (author) [fr

  6. The efficiency of aspheric intraocular lens according to biometric measurements.

    Science.gov (United States)

    Whang, Woong-Joo; Piao, Junjie; Yoo, Young-Sik; Joo, Choun-Ki; Yoon, Geunyoung

    2017-01-01

    To analyze internal spherical aberration in pseudophakic eyes that underwent aspheric intraocular lens (IOL) implantation, and to investigate the relationships between biometric data and the effectiveness of aspheric IOL implantation. This retrospective study included 40 eyes of 40 patients who underwent implantation of an IOL having a negative spherical aberration of -0.20 μm (CT ASPHINA 509M; Carl Zeiss Meditec Inc., Germany). The IOLMaster (version 5.0; Carl Zeiss AG, Germany) was used for preoperative biometric measurements (axial length, anterior chamber depth, central corneal power) and the measurement of postoperative anterior chamber depth. The spherical aberrations were measured preoperatively and 3 months postoperatively using the iTrace (Tracey Technologies, Houston, TX, USA) at a pupil diameter of 5.0 mm. We investigated the relationships between preoperative biometric data and postoperative internal spherical aberration, and compared biometric measurements between 2 subgroups stratified according to internal spherical aberration (spherical aberration ≤ -0.06 μm vs. spherical aberration > -0.06 μm). The mean postoperative internal spherical aberration was -0.087 ± 0.063 μm. Preoperative axial length and residual total spherical aberration showed statistically significant correlations with internal spherical aberration (p = 0.041, 0.002). Preoperative axial length, postoperative anterior chamber depth, IOL power, and residual spherical aberration showed significant differences between the 2 subgroups stratified according to internal spherical aberration (p = 0.020, 0.029, 0.048, 0.041 respectively). The corrective effect of an aspheric IOL is influenced by preoperative axial length and postoperative anterior chamber depth. Not only the amount of negative spherical aberration on the IOL surface but also the preoperative axial length should be considered to optimize spherical aberration after aspheric IOL implantation.

  7. Active optics: off axis aspherics generation for high contrast imaging

    Science.gov (United States)

    Hugot, E.; Laslandes, M.; Ferrari, M.; Vives, S.; Moindrot, S.; El Hadi, K.; Dohlen, K.

    2017-11-01

    Active Optics methods, based on elasticity theory, allow the aspherisation of optical surfaces by stress polishing but also active aspherisation in situ. Researches in this field will impact the final performance and the final cost of any telescope or instrument. The stress polishing method is well suited for the superpolishing of aspheric components for astronomy. Its principle relies on spherical polishing with a full-sized tool of a warped substrate, which becomes aspherical once unwarped. The main advantage of this technique is the very high optical quality obtained either on form or on high spatial frequency errors. Furthermore, the roughness can be decreased down to a few angstroms, thanks the classical polishing with a large pitch tool, providing a substantial gain on the final scientific performance, for instance on the contrast on coronagraphic images, but also on the polishing time and cost. Stress polishing is based on elasticity theory, and requires an optimised deformation system able to provide the right aspherical form on the optical surface during polishing. The optical quality of the deformation is validated using extensive Finite Element Analysis, allowing an estimation of residuals and an optimisation of the warping harness. We describe here the work realised on stress polishing of toric mirrors for VLT-SPHERE and then our actual work on off axis aspherics (OAA) for the ASPIICS-Proba3 mission for solar coronagraphy. The ASPIICS optical design made by Vives et al is a three mirrors anastigmat including a concave off axis hyperboloid and a convex off axis parabola (OAP). We are developing a prototype in order to demonstrate the feasibility of this type of surface, using a multi-mode warping harness (Lemaitre et al). Furthermore, we present our work on variable OAP, meaning the possibility to adjust the shape of a simple OAP in situ with a minimal number of actuators, typically one actuator per optical mode (Focus, Coma and Astigmatism

  8. On asphericity of convex bodies in linear normed spaces.

    Science.gov (United States)

    Faried, Nashat; Morsy, Ahmed; Hussein, Aya M

    2018-01-01

    In 1960, Dvoretzky proved that in any infinite dimensional Banach space X and for any [Formula: see text] there exists a subspace L of X of arbitrary large dimension ϵ -iometric to Euclidean space. A main tool in proving this deep result was some results concerning asphericity of convex bodies. In this work, we introduce a simple technique and rigorous formulas to facilitate calculating the asphericity for each set that has a nonempty boundary set with respect to the flat space generated by it. We also give a formula to determine the center and the radius of the smallest ball containing a nonempty nonsingleton set K in a linear normed space, and the center and the radius of the largest ball contained in it provided that K has a nonempty boundary set with respect to the flat space generated by it. As an application we give lower and upper estimations for the asphericity of infinite and finite cross products of these sets in certain spaces, respectively.

  9. Optical and visual performance of aspheric soft contact lenses.

    Science.gov (United States)

    Efron, Suzanne; Efron, Nathan; Morgan, Philip B

    2008-03-01

    This study was conducted to investigate whether aspheric design soft contact lenses reduce ocular aberrations and result in better visual acuity and subjective appreciation of clinical performance compared with spherical soft contact lenses. A unilateral, double-masked, randomized and controlled study was undertaken in which ocular aberrations and high and low contrast logMAR visual acuity were measured on myopic subjects who wore aspheric design (Biomedics 55 Evolution, CooperVision) and spherical design (Biomedics 55, CooperVision) soft contact lenses. Ten subjects who had about -2.00 D myopia wore -2.00 D lenses and 10 subjects who had about -5.00 D myopia wore -5.00 D lenses. Measurements were made under photopic and mesopic lighting conditions. Subjects were invited to grade comfort, vision in photopic and mesopic conditions, and overall impression with the two lens types on 100 unit visual analogue scales. There was no significant difference in high contrast or low contrast visual acuity between the two lens designs of either power under photopic or mesopic conditions. Both lens designs displayed lower levels of spherical aberration compared with the "no lens" condition under photopic and mesopic light levels (p designs. There were no statistically significant differences in subjective appreciation of clinical performance between lens designs or lens powers. At least with respect to the brand of lenses tested, the fitting of aspheric design soft contact lenses does not result in superior visual acuity, aberration control, or subjective appreciation compared with equivalent spherical design soft contact lenses.

  10. Improved illumination system of laparoscopes using an aspherical lens array.

    Science.gov (United States)

    Wu, Rengmao; Qin, Yi; Hua, Hong

    2016-06-01

    The current fiber-based illumination systems of laparoscopes are unable to uniformly illuminate a large enough area in abdomen due to the limited numerical aperture (NA) of the fiber bundle. Most energy is concentrated in a small region at the center of the illumination area. This limitation becomes problematic in laparoscopes which require capturing a wide field of view. In this paper, we propose an aspherical lens array which is used to direct the outgoing rays from the fiber bundle of laparoscope to produce a more uniformly illuminated, substantially larger field coverage than standalone fiber source. An intensity feedback method is developed to design the aspherical lens unit for extended non-Lambertian sources, which is the key to the design of this lens array. By this method, the lens unit is obtained after only one iteration, and the lens array is constructed by Boolean operation. Then, the ray-tracing technique is used to verify the design. Further, the lens array is fabricated and experimental tests are performed. The results clearly show that the well-illuminated area is increased to about 0.107m(2) from 0.02m(2) (about 5x larger than a standard fiber illumination source). More details of the internal organs can be clearly observed under this improved illumination condition, which also reflects the significant improvement in the optical performance of the laparoscope.

  11. Implementation of Bluetooth technology in processing aspheric mirrors

    Science.gov (United States)

    Chen, Dong-yun; Li, Xiao-jin

    2010-10-01

    This paper adopts the Bluetooth wireless transmission to replace the conducting rings currently using in the active lap process to overcome the cost and abrasion problems brought by the conducting rings, which has great significance for reducing the costs of processing large aspheric mirrors. Based on the actual application requirements, Article proposes the overall program of using Bluetooth technology as data transmission, including the active lap-side and machine tool-side: In the machine tool-side, the MCU separately connects with Bluetooth module and the sensor via UART0 and UART1 serial port, and when the MCU receives the signals sending from the sensor, the MCU packs and then sends them through the Bluetooth module; while in the active lap side, the CCAL reads-out the position signals of sensor detecting in dual-port memory via one-side ports, and the other side ports connect with the MCU's high ports P4-P7, so the MCU can unpacks and stores the position signals receiving via Bluetooth module. This paper designs and implements the system's hardware circuit, and mainly introduces the ways of serial and parallel. Based upon the realized system, design the test program for the Bluetooth wireless transmission and the experiment results, in the condition of the active lap processing large aspheric mirrors, showed that Bluetooth technology can meet the requirements of practical applications.

  12. From Spheric to Aspheric Solid Polymer Lenses: A Review

    Directory of Open Access Journals (Sweden)

    Kuo-Yung Hung

    2011-01-01

    Full Text Available This paper presents a new approach in the use of MEMS technology to fabricate micro-optofluidic polymer solid lenses in order to achieve the desired profile, focal length, numerical aperture, and spot size. The resulting polymer solid lenses can be applied in optical data storage systems, imaging systems, and automated optical inspection systems. In order to meet the various needs of different applications, polymer solid lenses may have a spherical or aspherical shape. The method of fabricating polymer solid lenses is different from methods used to fabricate tunable lenses with variable focal length or needing an external control system to change the lens geometry. The current trend in polymer solid lenses is toward the fabrication of microlenses with a high numerical aperture, small clear aperture (<2 mm, and high transmittance. In this paper we focus on the use of thermal energy and electrostatic force in shaping the lens profile, including both spherical and aspherical lenses. In addition, the paper discusses how to fabricate a lens with a high numerical aperture of 0.6 using MEMS and also compares the optical characteristics of polymer lens materials, including SU-8, Norland Optical Adhesive (NOA, and cyclic olefin copolymer (COC. Finally, new concepts and applications related to micro-optofluidic lenses and polymer materials are also discussed.

  13. Quality of vision in patients implanted with aspherical and spherical intraocular lens: Intraindividual comparison

    Directory of Open Access Journals (Sweden)

    Francesco Semeraro

    2014-01-01

    Full Text Available Aims: To compare the quality of vision in pseudophakic patients implanted with aspherical and spherical intraocular lenses (IOLs. Materials and Methods: Randomized prospective longitudinal intrapatient comparison between aspherical and spherical IOLs performed on 22 patients who underwent bilateral cataract surgery. Best corrected visual acuity, subjective contrast sensitivity, Strehl ratio and spherical aberrations (SA, and higher order wavefront aberrations for a 3.5 mm and a 6.0 mm pupil were measured after 3 months of cataract surgery. Results: SA (Z4,0 decreased significantly in eyes with aspherical IOL implant (P = 0.004. Modulation transfer function (MTF and point spread function (PSF resulted no significant difference between the two groups (P = 0.87; P = 0.32. Conclusion: Although the SA is significantly lower in eyes implanted with aspherical IOL, the quality of vision determined with MTF and PSF does not significantly differ for subjective and objective parameters that were analyzed.

  14. An Instrument for Inspecting Aspheric Optical Surfaces and Components, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Phase II SBIR proposal to develop an extremely versatile optical inspection tool for aspheric optical components and optics that are not easily inspected...

  15. An Instrument for Inspecting Aspheric Optical Surfaces and Components, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Phase I proposal to develop an extremely versatile optical inspection tool for determining the optical figure of aspheric optical components, such as test...

  16. Very large computer generated holograms for precision metrology of aspheric optical surfaces, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Both ground and space telescopes employ aspheric mirrors. A particular example is the X-ray telescope where primary and secondary mirrors have nearly cylindrical...

  17. A feasible injection molding technique for the manufacturing of large diameter aspheric plastic lenses

    Science.gov (United States)

    Shieh, Jen-Yu; Wang, Luke K.; Ke, Shih-Ying

    2010-07-01

    A computer aided engineering (CAE) tool-assisted technique, using Moldex3D and aspheric analysis utility (AAU) software in a polycarbonate injection molding design, is proposed to manufacture large diameter aspheric plastic lenses. An experiment is conducted to verify the applicability/feasibility of the proposed technique. Using the preceding two software tools, these crucial process parameters associated with the surface profile errors and birefringence of a molded lens can be attainable. The strategy adopted here is to use the actual quantity of shrinkage after an injection molding trial of an aspherical plastic lens as a reference to perform the core shaping job while keeping the coefficients of aspheric surface, radius, and conic constant unchanged. The design philosophy is characterized by using the CAE tool as a guideline to pursue the best symmetry condition, followed by injection molding trials, to accelerate a product’s developmental time. The advantages are less design complexity and shorter developmental time for a product.

  18. Research on the method of improving the accuracy of CMM (coordinate measuring machine) testing aspheric surface

    Science.gov (United States)

    Cong, Wang; Xu, Lingdi; Li, Ang

    2017-10-01

    Large aspheric surface which have the deviation with spherical surface are being used widely in various of optical systems. Compared with spherical surface, Large aspheric surfaces have lots of advantages, such as improving image quality, correcting aberration, expanding field of view, increasing the effective distance and make the optical system compact, lightweight. Especially, with the rapid development of space optics, space sensor resolution is required higher and viewing angle is requred larger. Aspheric surface will become one of the essential components in the optical system. After finishing Aspheric coarse Grinding surface profile error is about Tens of microns[1].In order to achieve the final requirement of surface accuracy,the aspheric surface must be quickly modified, high precision testing is the basement of rapid convergence of the surface error . There many methods on aspheric surface detection[2], Geometric ray detection, hartmann detection, ronchi text, knifeedge method, direct profile test, interferometry, while all of them have their disadvantage[6]. In recent years the measure of the aspheric surface become one of the import factors which are restricting the aspheric surface processing development. A two meter caliber industrial CMM coordinate measuring machine is avaiable, but it has many drawbacks such as large detection error and low repeatability precision in the measurement of aspheric surface coarse grinding , which seriously affects the convergence efficiency during the aspherical mirror processing. To solve those problems, this paper presents an effective error control, calibration and removal method by calibration mirror position of the real-time monitoring and other effective means of error control, calibration and removal by probe correction and the measurement mode selection method to measure the point distribution program development. This method verified by real engineer examples, this method increases the original industrial

  19. A framework of cloud supported collaborative design in glass lens moulds based on aspheric measurement

    Science.gov (United States)

    Zhu, Yongjian; Wang, Yu; Na, Jingxin; Zhi, Yanan; Fan, Yufeng

    2013-09-01

    Aspheric mould design includes the top-down design and reversal design. In this paper, a new framework of reversal design is proposed combining with cloud supported collaborative design (CSCD) based on aspheric measurement. The framework is a kind of collaborative platform, which is composed of eight modules, including the computerized aspheric precision measurement module (CAPM), computer-aided optical design of aspheric lens system (CAOD), computer-aided design of lens mould (CADLM), FEM(finite element method) simulation of lens molding module (FEMLM), computer-aided manufacture of lens and moulds (CAMLM), measurement data analysis module (MDAM), optical product lifecycle management module (OPLM) and cloud computing network module (CCNM). In this framework, the remote clients send an improved requirement or fabrication demand about optical lens system through CCNM, which transfers this signal to OPLM. In OPLM, one main server is in charge of the task distribution and collaborative work of other six modules. The first measurement data of aspheric lens are produced by clients or our proposed platform CAPM, then are sent to CAOD for optimization and the electronic drawings of lens moulds are generated in CADLM module. According the design drawings, the FEMLM could give the lens-molding simulation parameters through FEM software. The simulation data are used for the second design of moulds in CADLM module. In this case, the moulds could be fabricated in CAMLM by ultra-precision machine, and the aspheric lens could be also produced by lens-molding machine in CAMLM. At last, the final shape of aspheric lens could be measured in CAPM and the data analysis could be conducted in MDAM module. Through the proposed framework, all the work described above could be performed coordinately. And the optimum design data of lens mould could be realized and saved, then shared by all the work team.

  20. Study on combined polishing process of aspherical aluminum mirrors

    Science.gov (United States)

    Deng, Jinqiu; Peng, Xiaoqiang; Hu, Hao; Ge, Kunpeng

    2017-10-01

    The aluminum mirrors are widely used as important optical components in some vital fields such as astronomical instruments or military installations due to the unique advantages of aluminum alloy. In order to simplify the structure of optical system and improve the performance at the same time, it's a tendency that the optics will be designed to aspherical or other freeform shapes. However, the traditional techniques are falling to have adequate abilities to deal with the increasing demands of aluminum optics. For example, the tool marks leaved on the surface from single point diamond turning (SPDT) has obvious adverse effects to optical system. The deterministic and sub-aperture polishing process has showed the potential to fabricate complex shapes over the few years. But it's still recognized as a problem to polish bare aluminum directly because of its soft surface and active chemical characteristics. Therefore, a combination of magnetorheological finishing (MRF) and small tool polishing (STP) is applied to obtain high performance aluminum optics in this paper. A paraboloid aluminum mirror was polished with this proposed method, and the results showed that the surface texture of the sample is restrained from rms 0.409λ (λ=632.8nm) to rms 0.025λ, and the surface roughness is improved from average Ra 6 7nm to Ra 3 4nm.

  1. Simulation of an Aspheric Glass Lens Forming Behavior in Progressive GMP Process

    International Nuclear Information System (INIS)

    Chang, Sung Ho; Lee, Young Min; Kang, Jeong Jin; Hong, Seok Kwan; Shin, Gwang Ho; Heo, Young Moo; Jung, Tae Sung

    2007-01-01

    Recently, GMP(Glass Molding Press) process is mainly used to produce aspheric glass lenses. Because glass lens is heated at high temperature above Tg (Transformation Temperature) for forming the glass, the quality of aspheric glass lens is deteriorated by residual stresses which are generated in a aspheric glass lens after forming. In this study, as a fundamental study to develop the mold for progressive GMP process, we conducted a aspheric glass lens forming simulation. Prior to a aspheric glass lens forming simulation, compression and thermal conductivity tests were carried out to obtain mechanical and thermal properties of K-PBK40 which is newly developed material for precision molding, and flow characteristics of K-PBK40 were obtained at high temperature. Then, using the flow characteristics obtained, compression simulation was carried out and compared with the experimental result for the purpose of verifying the obtained flow characteristics. Finally, a glass lens press simulation in progressive GMP process was carried out and we could forecast the shape of deformed glass lenses and residual stresses contribution in the structure of deformed glass lenses after forming

  2. Influence of aspheric intraocular lens on frequency doubling technology and contrast sensitivity: a fellow eye study

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2014-12-01

    Full Text Available Purpose: To evaluate whether implantation of an aspheric intraocular lens (IOL results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery and, therefore, changes on frequency-doubling technology (FDT testing. Methods: The present prospective clinical study enrolled 25 patients with bilateral cataract (50 eyes, who randomly received either an aspheric (Akreos AO or a spherical (Akreos Fit IOL in one eye and the other IOL in the second eye. Assessment 12 months postoperatively included photopic and mesopic contrast sensitivity testing. Higher-order aberrations (HOAs were computed. FDT testing was divided into four areas to evaluate the variation of the values at different points. The median values of the local pattern thresholds (median area contrast sensitivity [MACS] obtained with that division were calculated. Results: The Akreos AO group obtained statistically significantly lower values of HOAs and spherical aberration compared with the Akreos Fit group. There was a statistically significant between-group difference in contrast sensitivity under mesopic conditions at all spatial frequencies. No statistically significant differences were observed in mean deviation and pattern standard deviation. The aspheric IOL exhibited higher MACS in all areas, although a statistically significant difference was reached only in the 20-degree field area (P=0.043. Conclusion: Aspheric IOLs significantly reduced spherical aberration and HOAs, improving mesopic contrast sensitivity. Although there was a trend toward slightly improved FDT in the aspheric IOL group, it was not statistically significant.

  3. Effect of aspherical and yellow tinted intraocular lens on blue-on-yellow perimetry

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2012-10-01

    Full Text Available PURPOSE: To investigate the possible effect of aspherical or yellow tinted intraocular lens (IOL on contrast sensitivity and blue-on-yellow perimetry. METHODS: This prospective randomized bilateral double-masked clinical study included 52 patients with visually significant bilateral cataracts divided in two groups; 25 patients (50 eyes received aspherical intraocular lens in one eye and spherical intraocular lens in the fellow eye; and 27 patients (54 eyes received ultraviolet and blue light filter (yellow tinted IOL implantation in one eye and acrylic ultraviolet filter IOL in the fellow eye. The primary outcome measures were contrast sensitivity and blue-on-yellow perimetry values (mean deviation [MD] and pattern standard deviation [PSD] investigated two years after surgery. The results were compared intra-individually. RESULTS: There was a statistically significant between-group (aspherical and spherical intraocular lens difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. There were no between-group significant differences (yellow tinted and clear intraocular lens under photopic or mesopic conditions. There was no statistically significant difference between all intraocular lens in MD or PSD. CONCLUSION: Contrast sensitivity was better under mesopic conditions with aspherical intraocular lens. Blue-on-yellow perimetry did not appear to be affected by aspherical or yellow tinted intraocular lens. Further studies with a larger sample should be carried out to confirm or not that hypotheses.

  4. Refractive lens exchange with a multifocal diffractive aspheric intraocular lens

    Directory of Open Access Journals (Sweden)

    Teresa Ferrer-Blasco

    2012-06-01

    Full Text Available PURPOSE: To evaluate the safety, efficacy and predictability after refractive lens exchange with multifocal diffractive aspheric intraocular lens implantation. METHODS: Sixty eyes of 30 patients underwent bilateral implantation with AcrySof® ReSTOR® SN6AD3 intraocular lens with +4.00 D near addition. Patients were divided into myopic and hyperopic groups. Monocular best corrected visual acuity at distance and near and monocular uncorrected visual acuity at distance and near were measured before and 6 months postoperatively. RESULTS: After surgery, uncorrected visual acuity was 0.08 ± 0.15 and 0.11 ± 0.14 logMAR for the myopic and hyperopic groups, respectively (50% and 46.67% of patients had an uncorrected visual acuity of 20/20 or better in the myopic and hyperopic groups, respectively. The safety and efficacy indexes were 1.05 and 0.88 for the myopic and 1.01 and 0.86 for the hyperopic groups at distance vision. Within the myopic group, 20 eyes remained unchanged after the surgery, and 3 gained >2 lines of best corrected visual acuity. For the hyperopic group, 2 eyes lost 2 lines of best corrected visual acuity, 21 did not change, and 3 eyes gained 2 lines. At near vision, the safety and efficacy indexes were 1.23 and 1.17 for the myopic and 1.16 and 1.13 for the hyperopic groups. Best corrected near visual acuity improved after surgery in both groups (from 0.10 logMAR to 0.01 logMAR in the myopic group, and from 0.10 logMAR to 0.04 logMAR in the hyperopic group. CONCLUSIONS: The ReSTOR® SN6AD3 intraocular lens in refractive lens exchange demonstrated good safety, efficacy, and predictability in correcting high ametropia and presbyopia.

  5. Measurement of aspheric surfaces using an improved annular subaperture stitching interferometry (IASSI)

    International Nuclear Information System (INIS)

    Wen, Yongfu; Cheng, Haobo

    2014-01-01

    An improved annular subaperture stitching interferometry (IASSI) is proposed for testing aspheric surfaces in the stage of precision polishing. It includes a reasonable stitching model and an automatic positioning operation. In the testing process, a series of optical path difference (OPD) data of annular subapertures is obtained as the interferometer is gradually shifted relative to the tested aspheric surface. Then these OPD data can be analyzed by the automatic positioning operation to get the key stitching parameters, and can be stitched together based on a reasonable mathematical model. To verify its validity, we study the applicability of the method to subaperture stitching tests of two conic aspheric surfaces. The stitching results agreed with the full-aperture test results. (paper)

  6. We are not the 99 percent: quantifying asphericity in the distribution of Local Group satellites

    Science.gov (United States)

    Forero-Romero, Jaime E.; Arias, Verónica

    2018-05-01

    We use simulations to build an analytic probability distribution for the asphericity in the satellite distribution around Local Group (LG) type galaxies in the Lambda Cold Dark Matter (LCDM) paradigm. We use this distribution to estimate the atypicality of the satellite distributions in the LG even when the underlying simulations do not have enough systems fully resembling the LG in terms of its typical masses, separation and kinematics. We demonstrate the method using three different simulations (Illustris-1, Illustris-1-Dark and ELVIS) and a number of satellites ranging from 11 to 15. Detailed results differ greatly among the simulations suggesting a strong influence of the typical DM halo mass, the number of satellites and the simulated baryonic effects. However, there are three common trends. First, at most 2% of the pairs are expected to have satellite distributions with the same asphericity as the LG; second, at most 80% of the pairs have a halo with a satellite distribution as aspherical as in M31; and third, at most 4% of the pairs have a halo with satellite distribution as planar as in the MW. These quantitative results place the LG at the level of a 3σ outlier in the LCDM paradigm. We suggest that understanding the reasons for this atypicality requires quantifying the asphericity probability distribution as a function of halo mass and large scale environment. The approach presented here can facilitate that kind of study and other comparisons between different numerical setups and choices to study satellites around LG pairs in simulations.

  7. Application for vibration monitoring of aspheric surface machining based on wireless sensor networks

    Science.gov (United States)

    Han, Chun Guang; Guo, Yin Biao; Jiang, Chen

    2010-05-01

    Any kinds of tiny vibration of machine tool parts will have a great influence on surface quality of the workpiece at ultra-precise machining process of aspheric surface. At present the major way for decreasing influence of vibration is machining compensation technology. Therefore it is important for machining compensation control to acquire and transmit these vibration signals effectively. This paper presents a vibration monitoring system of aspheric surface machining machine tool based on wireless sensor networks (WSN). Some key issues of wireless sensor networks for vibration monitoring system of aspheric surface machining are discussed. The reliability of data transmission, network communication protocol and synchronization mechanism of wireless sensor networks are studied for the vibration monitoring system. The proposed system achieves multi-sensors vibration monitoring involving the grinding wheel, the workpiece and the workbench spindle. The wireless transmission of vibration signals is achieved by the combination with vibration sensor nodes and wireless network. In this paper, these vibration sensor nodes are developed. An experimental platform is structured which employs wireless sensor networks to the vibration monitoring system in order to test acquisition and wireless transmission of vibration signal. The test results show that the proposed system can achieve vibration data transmission effectively and reliability and meet the monitoring requirements of aspheric surface machining machine tool.

  8. Evaluation of visual quality of spherical and aspherical intraocular lenses by Optical Quality Analysis System

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2017-06-01

    Full Text Available AIM: To evaluate the impact of spherical and aspherical intraocular lenses on the postoperative visual quality of age-related cataract patients using Optical Quality Analysis System (OQAS. METHODS: Seventy-four eyes with age-related cataracts were randomly divided into spherical and aspherical lens implantation groups. Best-corrected visual acuity (BCVA was measured preoperatively, one day, one week, two weeks, one month and two months after surgery. A biometric systems analysis using the OQAS objective scattering index (OSI was performed. RESULTS: There were no significant differences in visual acuity (P>0.05 before and after spherical and aspheric lens implantation. There was a negative linear correction between the OSI value and BCVA (r=-0.634, P=0.000, and positive corrections between the OSI value and the lens LOCUS III value of nucleus color (NC, nucleus opacity (NO, cortex (C and posterior lens capsular (P (r=0.704, P=0.000; r=0.514, P=0.000; r=0.276, P=0.020; r=0.417, P=0.000, respectively. OSI values of spherical vs aspherical lenses were 11.5±3.6 vs 11.8±3.4, 4.1±0.9 vs 3.3±0.8, 3.5±0.9 vs 2.7±0.7, 3.3±0.8 vs 2.6±0.7, 3.2±0.7 vs 2.5±0.8, and 3.2±0.8 vs 2.5±0.8 before and 1d, 1, 2wk, 1 and 2mo after surgery, respectively. All time points varied significantly (P<0.01 between the two groups. CONCLUSION: Aspherical IOLs does not significantly affect visual acuity compared with spherical IOLs. The OSI value, was significantly lower in the aspherical lens group compared with the spherical lens. This study shows that objective visual quality of aspheric IOLs is better than that of the spherical lens by means of OQAS biological measurement method.

  9. Glass molding of 3mm diameter aspheric plano-convex lens

    Science.gov (United States)

    Sung, Hayeong; Hue, Myung sang; Lee, Giljae; Ryu, Geunman; Kim, Dongguk; Yang, Suncheol

    2017-10-01

    The many industries and research fields have demands for small scale optical systems. To satisfy the demands, many studies are conducted and the miniaturization technologies have been developed. The optical lens is directly related to the optical systems and a key component for the miniaturization. So the aspheric surface which can replace multispherical lenses is applied to the optical lens. And fabrication methods to reduce the diameter of the lens have been developed. The glass molding pressing (GMP) process is an attractive method to fabricate aspheric lens among the lens manufacturing processes. Because the GMP process has advantages of productivity, repeatability and so on. In this study, a 3 mm diameter aspheric plano-convex lens was fabricated using the GMP process. The GMP process was divided into heating, pressing, annealing and cooling. And the process was conducted using a commercial glass molding machine. Mold tools consist of an upper and a lower mold insert, an inner and an outer guide. The aspheric and the flat surfaces of the mold inserts were coated with ta-C to prevent the sticking of the glass to the mold. The surfaces of molded lens were measured by white interferometry and surface profilometer. The height and the diameter were measured using optical microscopy. As results, the aspheric surface of the lens was 5.1187 nm in Ra and 0.242 um in Pt. And the flat surface was 2.6697 nm in Ra and 0.13 um in Pt. The height and the diameter were 1.935 mm and 3.002 mm respectively.

  10. Visual outcome and optical quality after bilateral implantation of aspheric diffractive multifocal, aspheric monofocal and spherical monofocal intraocular lenses: a prospective comparison

    Directory of Open Access Journals (Sweden)

    Ke Yao

    2013-06-01

    Full Text Available AIM: To evaluate the visual function after bilateral implantation of aspheric diffractive multifocal Tecnis ZMA00, aspheric monofocal ZA9003 versus spherical monofocal Akreos Adapt intraocular lenses (IOLs.METHODS: Tecnis ZMA00, Tecnis ZA9003 or Akreos Adapt IOLs were bilaterally implanted in 180 eyes from 90 patients. The following parameters were assessed 3 months postoperatively: monocular and binocular uncorrected visual acuity (UCVA and distance-corrected visual acuity (DCVA for distance, intermediate and near, spherical aberration (SA, contrast and glare sensitivity, near point refractive power, uncorrected and best-corrected near stereoscopic acuity (NSA. Patient satisfaction was assessed by a questionnaire.RESULTS: Three months postoperatively, the monocular and binocular UCVA and DCVA at near of Tecnis ZMA00 were significantly better than other two groups. The mean SA for 5.0mm optical zone in Tecnis ZMA00 and Tecnis ZA9003 was significantly lower than that in Akreos Adapt. Mean contrast sensitivity and glare sensitivity were better for Tecnis ZA9003 group than for other two groups. Patients with Tecnis ZMA00 had higher monocular and binocular near point refractive power and uncorrected NSA than monofocal groups. The patients in Tecnis ZMA00 had higher mean values for halo compared with other two groups.CONCLUSION: Tecnis ZMA00 provided better near VA and uncorrected NSA and higher near point refractive power than monofocal IOLs and patients were spectacle independent. The IOLs with Tecnis aspheric design improved contrast and glare sensitivity. Patients with Tecnis ZMA00 reported more disturbances on visual phenomena of halo.

  11. Refractive outcomes of an advanced aspherically optimized profile for myopia corrections by LASIK: a retrospective comparison with the standard aspherically optimized profile

    Directory of Open Access Journals (Sweden)

    Meyer B

    2015-02-01

    Full Text Available Bertram Meyer,1 Georg Sluyterman van Langeweyde,2 Matthias Wottke2 1Augencentrum Köln, Cologne, Germany; 2Carl Zeiss Meditec AG, Jena, Germany Purpose: A retrospective comparison of refractive outcomes of a new, aspherically optimized profile with an enhanced energy correction feature (Triple-A and the conventionally used aspherically optimized profile (ASA, or aberration smart ablation for correction of low-to-high myopia.Setting: Augen-OP-Centrum, Cologne, GermanyDesign: Retrospective nonrandomized comparative studyMethods: A central database at the Augen-OP-Centrum was used to gather retrospective data for low-to-high myopia (up to -10 D. One hundred and seven eyes (56 patients were treated with the ASA profile, and 79 eyes (46 patients were treated with the Triple-A profile. Postoperative outcomes were evaluated at 1 month, 3 months, 6 months, and 1 year follow-up time points.Results: The Triple-A profile showed better predictability indicated by a significantly lower standard deviation of residuals (0.32–0.34 vs 0.36–0.44, Triple-A vs ASA in the 6-month to 1-year period. The Triple-A group had better stability across all time intervals and achieved better postoperative astigmatism improvements with significantly lower scatter. This group achieved better safety at 1 year, with 100% of eyes showing no change or gain in Snellen lines, compared with 97% in the ASA group. A better safety index was observed for the Triple-A group at later time points. The Triple-A group had a better efficacy index and a higher percentage of eyes with an uncorrected Snellen visual acuity of 20/20 or greater at all investigated follow-up time points.Conclusion: The new aspherically optimized Triple-A profile can safely and effectively correct low-to-high myopia. It has demonstrated superiority over the ASA profile in most refractive outcomes. Keywords: Triple-A, wavefront measurements, corneal aberrations, corneal asphericity, ablation profile

  12. Manufacturing aspheric mirrors made of zero thermal expansion cordierite ceramics using Magnetorheological Finishing (MRF)

    Science.gov (United States)

    Sugawara, Jun; Maloney, Chris

    2016-07-01

    NEXCERATM cordierite ceramics, which have ultra-low thermal expansion properties, are perfect candidate materials to be used for light-weight satellite mirrors that are used for geostationary earth observation and for mirrors used in ground-based astronomical metrology. To manufacture the high precision aspheric shapes required, the deterministic aspherization and figure correction capabilities of Magnetorheological Finishing (MRF) are tested. First, a material compatibility test is performed to determine the best method for achieving the lowest surface roughness of RMS 0.8nm on plano surfaces made of NEXCERATM ceramics. Secondly, we will use MRF to perform high precision figure correction and to induce a hyperbolic shape into a conventionally polished 100mm diameter sphere.

  13. Optimal design of tilt carrier frequency computer-generated holograms to measure aspherics.

    Science.gov (United States)

    Peng, Jiantao; Chen, Zhe; Zhang, Xingxiang; Fu, Tianjiao; Ren, Jianyue

    2015-08-20

    Computer-generated holograms (CGHs) provide an approach to high-precision metrology of aspherics. A CGH is designed under the trade-off among size, mapping distortion, and line spacing. This paper describes an optimal design method based on the parametric model for tilt carrier frequency CGHs placed outside the interferometer focus points. Under the condition of retaining an admissible size and a tolerable mapping distortion, the optimal design method has two advantages: (1) separating the parasitic diffraction orders to improve the contrast of the interferograms and (2) achieving the largest line spacing to minimize sensitivity to fabrication errors. This optimal design method is applicable to common concave aspherical surfaces and illustrated with CGH design examples.

  14. Conformal Interpolating Algorithm Based on Cubic NURBS in Aspheric Ultra-Precision Machining

    International Nuclear Information System (INIS)

    Li, C G; Zhang, Q R; Cao, C G; Zhao, S L

    2006-01-01

    Numeric control machining and on-line compensation for aspheric surface are key techniques in ultra-precision machining. In this paper, conformal cubic NURBS interpolating curve is applied to fit the character curve of aspheric surface. Its algorithm and process are also proposed and imitated by Matlab7.0 software. To evaluate the performance of the conformal cubic NURBS interpolation, we compare it with the linear interpolations. The result verifies this method can ensure smoothness of interpolating spline curve and preserve original shape characters. The surface quality interpolated by cubic NURBS is higher than by line. The algorithm is benefit to increasing the surface form precision of workpieces in ultra-precision machining

  15. Using neutral network to infer the hydrodynamic yield of aspherical sources

    International Nuclear Information System (INIS)

    Moran, B.; Glenn, L.A.

    1993-07-01

    We distinguish two kinds of difficulties with yield determination from aspherical sources. The first kind, the spoofing difficulty, occurs when a fraction of the energy of the explosion is channeled in such a way that it is not detected by the CORRTEX cable. In this case, neither neural networks nor any expert system can be expected to accurately estimate the yield without detailed information about device emplacement within the canister. Numerical simulations however, can provide an upper bound on the undetected fraction of the explosive energy. In the second instance, the interpretation difficulty, the data appear abnormal when analyzed using similar-explosion-scaling and the assumption of a spherical front. The inferred yield varies with time and the confidence in the yield estimate decreases. It is this kind of problem we address in this paper and for which neural networks can make a contribution. We used a back propagation neural network to infer the hydrodynamic yield of simulated aspherical sources. We trained the network using a subset of simulations from 3 different aspherical sources, with 3 different yields, and 3 satellite offset separations. The trained network was able to predict the yield within 15% in all cases and to identify the correct type of aspherical source in most cases. The predictive capability of the network increased with a larger training set. The neural network approach can easily incorporate information from new calculations or experiments and is therefore flexible and easy to maintain. We describe the potential capabilities and limitations in using such networks for yield estimations

  16. Method for producing an isoplanatic aspheric monofocal intraocular lens, and resul ting lens

    OpenAIRE

    Barbero, Sergio; Marcos, Susana; Dorronsoro, Carlos; Montejo, Javier; Salazar Salegui, Pedro

    2010-01-01

    [EN] The invention can be used to obtain isoplanatic aspheric mono focal intraocular lenses in a viewing range of up to 25° (preferably up to 10°). The method comprises the following steps: l. mathematical defmition of an aphakic eye model; 2. mathematical definition of an intraocular lens model; 3. mathematical defmition of the implantation of the lens; 4. mathematical defmition of the merit function; 5. definition of the contour conditions; 6. defmition of a measurement for charact...

  17. Using neural networks to infer the hydrodynamic yield of aspherical sources

    International Nuclear Information System (INIS)

    Moran, B.; Glenn, L.

    1993-01-01

    We distinguish two kinds of difficulties with yield determination from aspherical sources. The first kind, the spoofing difficulty, occurs when a fraction of the energy of the explosion is channeled in such a way that it is not detected by the CORRTEX cable. In this case, neither neural networks nor any expert system can be expected to accurately estimate the yield without detailed information about device emplacement within the canister. Numerical simulations however, can provide an upper bound on the undetected fraction of the explosive energy. In the second instance, the interpretation difficulty, the data appear abnormal when analyzed using similar-explosion-scaling and the assumption of a spherical front. The inferred yield varies with time and the confidence in the yield estimate decreases. It is this kind of problem we address in this paper and for which neural networks can make a contribution. We used a back propagation neural network to infer the hydrodynamic yield of simulated aspherical sources. We trained the network using a subset of simulations from 3 different aspherical sources, with 3 different yield, and 3 satellite offset separations. The trained network was able to predict the yield within 15% in all cases and to identify the correct type of aspherical source in most cases. The predictive capability of the network increased with a larger training set. The neural network approach can easily incorporate information from new calculations or experiments and is therefore flexible and easy to maintain. We describe the potential capabilities and limitations in using such networks for yield estimations

  18. Solutions on a high-speed wide-angle zoom lens with aspheric surfaces

    Science.gov (United States)

    Yamanashi, Takanori

    2012-10-01

    Recent development in CMOS and digital camera technology has accelerated the business and market share of digital cinematography. In terms of optical design, this technology has increased the need to carefully consider pixel pitch and characteristics of the imager. When the field angle at the wide end, zoom ratio, and F-number are specified, choosing an appropriate zoom lens type is crucial. In addition, appropriate power distributions and lens configurations are required. At points near the wide end of a zoom lens, it is known that an aspheric surface is an effective means to correct off-axis aberrations. On the other hand, optical designers have to focus on manufacturability of aspheric surfaces and perform required analysis with respect to the surface shape. Centration errors aside, it is also important to know the sensitivity to aspheric shape errors and their effect on image quality. In this paper, wide angle cine zoom lens design examples are introduced and their main characteristics are described. Moreover, technical challenges are pointed out and solutions are proposed.

  19. Registration of eye reflection and scene images using an aspherical eye model.

    Science.gov (United States)

    Nakazawa, Atsushi; Nitschke, Christian; Nishida, Toyoaki

    2016-11-01

    This paper introduces an image registration algorithm between an eye reflection and a scene image. Although there are currently a large number of image registration algorithms, this task remains difficult due to nonlinear distortions at the eye surface and large amounts of noise, such as iris texture, eyelids, eyelashes, and their shadows. To overcome this issue, we developed an image registration method combining an aspherical eye model that simulates nonlinear distortions considering eye geometry and a two-step iterative registration strategy that obtains dense correspondence of the feature points to achieve accurate image registrations for the entire image region. We obtained a database of eye reflection and scene images featuring four subjects in indoor and outdoor scenes and compared the registration performance with different asphericity conditions. Results showed that the proposed approach can perform accurate registration with an average accuracy of 1.05 deg by using the aspherical cornea model. This work is relevant for eye image analysis in general, enabling novel applications and scenarios.

  20. In vivo chromatic aberration in eyes implanted with intraocular lenses.

    Science.gov (United States)

    Pérez-Merino, Pablo; Dorronsoro, Carlos; Llorente, Lourdes; Durán, Sonia; Jiménez-Alfaro, Ignacio; Marcos, Susana

    2013-04-12

    To measure in vivo and objectively the monochromatic aberrations at different wavelengths, and the chromatic difference of focus between green and infrared wavelengths in eyes implanted with two models of intraocular lenses (IOL). EIGHTEEN EYES PARTICIPATED IN THIS STUDY: nine implanted with Tecnis ZB99 1-Piece acrylic IOL and nine implanted with AcrySof SN60WF IOL. A custom-developed laser ray tracing (LRT) aberrometer was used to measure the optical aberrations, at 532 nm and 785 nm wavelengths. The monochromatic wave aberrations were described using a fifth-order Zernike polynomial expansion. The chromatic difference of focus was estimated as the difference between the equivalent spherical errors corresponding to each wavelength. Wave aberration measurements were highly reproducible. Except for the defocus term, no significant differences in high order aberrations (HOA) were found between wavelengths. The average chromatic difference of focus was 0.46 ± 0.15 diopters (D) in the Tecnis group, and 0.75 ± 0.12 D in the AcrySof group, and the difference was statistically significant (P Chromatic difference of focus in the AcrySof group was not statistically significantly different from the Longitudinal chromatic aberration (LCA) previously reported in a phakic population (0.78 ± 0.16 D). The impact of LCA on retinal image quality (measured in terms of Strehl ratio) was drastically reduced when considering HOA and astigmatism in comparison with a diffraction-limited eye, yielding the differences in retinal image quality between Tecnis and AcrySof IOLs not significant. LRT aberrometry at different wavelengths is a reproducible technique to evaluate the chromatic difference of focus objectively in eyes implanted with IOLs. Replacement of the crystalline lens by the IOL did not increase chromatic difference of focus above that of phakic eyes in any of the groups. The AcrySof group showed chromatic difference of focus values very similar to physiological values in

  1. Manufacturing and control of the aspherical mirrors for the telescope of the satellite Pleiades

    Science.gov (United States)

    Ducollet, Hélène; du Jeu, Christian; Fermé, Jean-Jacques

    2017-11-01

    For the Pleiades space program, SESO has been awarded the contract (fully completed), for the manufacturing of the whole set of telescope mirrors (4 mirrors, 2 flight models). These works did also include the mechanical design, manufacturing and mounting of the attachment flexures between the mirrors and the telescope main structure. This presentation is focused on the different steps of lightweighting, polishing, integration and control of these mirrors as well as a presentation of the existing SESO facilities and capabilities to produce such kind of aspherical components/sub-assemblies.

  2. Nucleosynthesis in neutrino-driven, aspherical supernova explosion of a massive star

    International Nuclear Information System (INIS)

    Fujimoto, S.; Hashimoto, M.; Ono, M.; Kotake, K.; Ohnishi, N.

    2011-01-01

    We examine explosive nucleosynthesis of p-nuclei during a delayed neutrino-driven, aspherical supernova explosion aided by standing accretion shock instability, based on two-dimensional hydrodynamic simulations of the explosion of a 15M · star. We find that p-nuclei are mainly produced through γ-processes, and that the nuclei lighter than 92 Mo are abundantly synthesized in slightly neutron-rich bubbles with electron fractions of Y e ≤0.48. 94 Mo, 96 Ru, and 98 Ru, are underproduced compared with the solar system, as in the spherical model.

  3. Postoperative Corneal Asphericity in Low, Moderate, and High Myopic Eyes After Transepithelial PRK Using a New Pulse Allocation.

    Science.gov (United States)

    Lin, David T C; Holland, Simon P; Verma, Shwetabh; Hogden, John; Arba-Mosquera, Samuel

    2017-12-01

    To evaluate the postoperative asphericity in low, moderate, and high myopic eyes after combined transepithelial photorefractive keratectomy and SmartSurf ACE treatment (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). In this retrospective case series, the outcomes of myopic SmartSurf ACE were evaluated at 3 months postoperatively in 106 eyes and divided into low (less than -4.125 diopters [D]), moderate (-4.125 to -6.25 D), and high (more than -6.25 D) myopia groups. In all cases, standard examinations and preoperative and postoperative corneal topography (SCHWIND Sirius) were performed. The analysis comprised evaluating the change in asphericity versus planned correction, comparing expected and achieved postoperative asphericity for all eyes, and comparison of the three groups in terms of the preoperative and postoperatively expected and achieved asphericity. RESULTS At 3 months postoperatively, the low myopia group (n = 33) improved average negative asphericity (Q = -0.04 ± 0.17 preoperative vs -0.19 ± 0.20 postoperative, P .10), but showed significant differences postoperatively (P < .007). The cohort's average preoperative corrected distance visual acuity was 0.01 ± 0.04 logMAR (range: 0.0 to 0.18 logMAR) and uncorrected distance visual acuity was 0.03 ± 0.08 logMAR (range: -0.12 to 0.40 logMAR) 3 months postoperatively. SmartSurf ACE maintained or slightly improved preoperative corneal asphericity for low to moderate myopic corrections (up to -6.00 D). This may provide advantages in the quality of vision and the onset of presbyopic symptoms after laser refractive surgery in myopic patients. [J Refract Surg. 2017;33(12):820-826.]. Copyright 2017, SLACK Incorporated.

  4. Application of a virtual coordinate measuring machine for measurement uncertainty estimation of aspherical lens parameters

    International Nuclear Information System (INIS)

    Küng, Alain; Meli, Felix; Nicolet, Anaïs; Thalmann, Rudolf

    2014-01-01

    Tactile ultra-precise coordinate measuring machines (CMMs) are very attractive for accurately measuring optical components with high slopes, such as aspheres. The METAS µ-CMM, which exhibits a single point measurement repeatability of a few nanometres, is routinely used for measurement services of microparts, including optical lenses. However, estimating the measurement uncertainty is very demanding. Because of the many combined influencing factors, an analytic determination of the uncertainty of parameters that are obtained by numerical fitting of the measured surface points is almost impossible. The application of numerical simulation (Monte Carlo methods) using a parametric fitting algorithm coupled with a virtual CMM based on a realistic model of the machine errors offers an ideal solution to this complex problem: to each measurement data point, a simulated measurement variation calculated from the numerical model of the METAS µ-CMM is added. Repeated several hundred times, these virtual measurements deliver the statistical data for calculating the probability density function, and thus the measurement uncertainty for each parameter. Additionally, the eventual cross-correlation between parameters can be analyzed. This method can be applied for the calibration and uncertainty estimation of any parameter of the equation representing a geometric element. In this article, we present the numerical simulation model of the METAS µ-CMM and the application of a Monte Carlo method for the uncertainty estimation of measured asphere parameters. (paper)

  5. Tomographic inversion of P and pP data for aspherical mantle structure below the northwest Pacific region

    NARCIS (Netherlands)

    Hilst, R.D. van der; Engdahl, E.R.; Spakman, W.

    1993-01-01

    To investigate the morphology of subducted slab in the mantle below northwest Pacific island arcs we inverted traveltime residuals for aspherical variations in P-wave propagation velocity relative to the radially symmetric iasp91 reference model. The tomographic method used is based on a step-wise

  6. Avoiding unstable regions in the design space of EUV mirror systems comprising high-order aspheric surfaces

    NARCIS (Netherlands)

    Marinescu, O.; Bociort, F.; Braat, J.

    2004-01-01

    When Extreme Ultraviolet mirror systems having several high-order aspheric surfaces are optimized, the configurations often enter into highly unstable regions of the parameter space. Small changes of system parameters lead then to large changes in ray paths, and therefore optimization algorithms

  7. Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

    Directory of Open Access Journals (Sweden)

    L. Nichman

    2017-09-01

    Full Text Available Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD chamber at European Organisation for Nuclear Research (CERN. The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of −30, −40 and −50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI. Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot

  8. Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

    Science.gov (United States)

    Nichman, Leonid; Järvinen, Emma; Dorsey, James; Connolly, Paul; Duplissy, Jonathan; Fuchs, Claudia; Ignatius, Karoliina; Sengupta, Kamalika; Stratmann, Frank; Möhler, Ottmar; Schnaiter, Martin; Gallagher, Martin

    2017-09-01

    Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at European Organisation for Nuclear Research (CERN). The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of -30, -40 and -50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition) were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL) measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI). Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE) and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot separate perfectly

  9. Feasibility assessment of visual quality analyzer KR-1W guiding personalized aspheric IOL implantation

    Directory of Open Access Journals (Sweden)

    Xiao-Li Wang

    2015-01-01

    Full Text Available AIM: To discuss the feasibility of using the visual quality analyzer KR-1W to guide the relatively personalized aspheric intraocular lens(IOLimplants to make the whole eye spherical aberration close to 0.1μm.METHODS: In this prospective case series study, the corneal spherical aberration with 6mm aperture of 73 patients(100 eyeswas measured with KR-1W Visual Function Analyzer 1d before surgery. For the sake of the whole postoperative spherical aberration were close to 0.1μm, 9 cases(16 eyeswith corneal spherical aberration 0.35μm were implanted Tecnis ZA9003 IOL, named Tecnis group. Aspherical IOL was implanted after phacoemulsification through a cornea 2.75mm incision without suture.Uncorrected visual acuity, beat corrected visual acuity, spherical aberration of the whole eye and jnternal optics(mainly IOLat 6mm pupil diameter were examined at 3mo postoperatively. The relevant data were analyzed using t-test and variance analysis.RESULTS: The whole ocular spherical aberration at 6mm pupil diameter in all postoperative were 0.084±0.032μm; in Tecnis group, the data were 0.091 ± 0.021μm; in AO group, the data were 0.0814-0.013μm; IQ group were 0.093±0.042μm. There was no significantly different between the predicted value and actual value of ocular spherical aberration at 6 mm pupil diameter in all postoperative(t=1.932, P=0.061and in the three groups. The difference value in the predicted values of the preoperative spherical aberrations of the whole eye and the actual values after surgery was 0.013±0.041μm; there was no statistically significant difference(F=2.537, P=0.091. Respectively compared the uncorrected visual acuity and besta corrected visual acuity among three groups of postoperative, no significant difference were found(F=0.897, P=0.421; F=1.423, P=0.097.CONCLUSION: Personality selection of aspheric IOL based on preoperative corneal spherical aberration of patients is feasible and produces satisfactory target postoperative

  10. Photoflash unit having optical system including aspheric lens to enhance light output

    International Nuclear Information System (INIS)

    English, G.J.

    1984-01-01

    A photoflash unit employing an optical system or apparatus with improved center beam candle power seconds and zonal lumen seconds from the flash lamp therein, said unit also employing a minimized utilization ratio of lamp-to-package cross-sectional area. Each individual lamp capsule comprises a reflective element, a refractive element (lens), and at least one photoflash lamp (light source). The lens provides for lamp shred magnification so as to fill the cell (capsule) width to thus provide maximum transfer of light to the subject on axis. One embodiment has the light source fused (glued) to the reflector and lens while a second embodiment has an air interface between the source and the optical elements. In both embodiments, the lens is aspheric and substantially covers both the reflector and source

  11. Wide-Spectrum Microscope with a Long Working Distance Aspherical Objective Based on Obscuration Constraint

    Directory of Open Access Journals (Sweden)

    Weibo Wang

    2016-11-01

    Full Text Available We present an approach for an initial configuration design based on obscuration constraint and on-axis Taylor series expansion to realize the design of long working distance microscope (numerical aperture (NA = 0.13 and working distance (WD = 525 mm with a low obscuration aspherical Schwarzschild objective in wide-spectrum imaging (λ = 400–900 nm. Experiments of the testing on the resolution target and inspection on United States Air Force (USAF resolution chart and a line charge-coupled device (CCD (pixel size of 14 μm × 56 μm with different wavelength light sources (λ = 480 nm, 550 nm, 660 nm, 850 nm were implemented to verify the validity of the proposed method.

  12. Measuring large aspherics using a commercially available 3D-coordinate measuring machine

    Science.gov (United States)

    Otto, Wolfgang; Matthes, Axel; Schiehle, Heinz

    2000-07-01

    A CNC-controlled precision measuring machine is a very powerful tool in the optical shop not only to determine the surface figure, but also to qualify the radius of curvature and conic constant of aspherics. We used a commercially available 3D-coordinate measuring machine (CMM, ZEISS UPMC 850 CARAT S-ACC) to measure the shape of the GEMINI 1-m convex secondary mirrors at different lapping and polishing stages. To determine the measuring accuracy we compared the mechanical measurements with the results achieved by means of an interferometrical test setup. The data obtained in an early stage of polishing were evaluated in Zernike polynomials which show a very good agreement. The deviation concerning long wave rotational symmetrical errors was 20 nm rms, whereas the accuracy measuring of mid spatial frequency deviations was limited to about 100 nm rms.

  13. Aspherical nucleosynthesis in a core-collapse supernova with 25 M {sub ☉} standard progenitor

    Energy Technology Data Exchange (ETDEWEB)

    Popov, M. V. [École Normale Supérieure de Lyon, CRAL (UMR CNRS 5574), Université de Lyon 1, 46 allée d' Italie, F-69007 Lyon (France); Filina, A. A.; Baranov, A. A.; Chardonnet, P. [LAPTh, Université de Savoie, 9, Chemin de Bellevue BP 110, F-74941 Annecy-le-Vieux Cedex (France); Chechetkin, V. M. [Keldysh Institute of Applied Mathematics RAS, Miusskaya sq. 4, 125047 Moscow (Russian Federation)

    2014-03-01

    The problem of nucleosynthesis was studied within an aspherical supernova model. The explosive burning was computed in a star of 25 M {sub ☉} initial mass on its final stage of evolution. The chemical composition of a presupernova was taken from realistic evolutionary computations. A piecewise parabolic method on a local stencil was applied to simulate the hydrodynamics of the explosion. The gravity was recomputed by a Poisson solver on a fine grid as the explosion developed. A detailed yield of chemical elements was performed as a post-processing step using the tracer particles method. The produced nuclei formed a layer-like structure enclosing large fragments of nickel and iron-group isotopes that were pushed away from the central region by an explosion along the polar direction. The light nuclei were preferentially moving along the equatorial plane forming a torus-like structure.

  14. Effect of Spherical Aberration on the Optical Quality after Implantation of Two Different Aspherical Intraocular Lenses

    Directory of Open Access Journals (Sweden)

    Michael Lasta

    2017-01-01

    Full Text Available Purpose. To compare the effect of spherical aberration on optical quality in eyes with two different aspherical intraocular lenses. Methods. 120 eyes of 60 patients underwent phacoemulsification. In patients’ eyes, an aberration-free IOL (Aspira-aA; Human Optics or an aberration-correcting aspherical IOL (Tecnis ZCB00; Abott Medical Optics was randomly implanted. After surgery, contrast sensitivity and wavefront measurements as well as tilt and decentration measurements were performed. Results. Contrast sensitivity was significantly higher in eyes with Aspira lens under mesopic conditions with 12 cycles per degree (CPD and under photopic conditions with 18 CPD (p=0.02. Wavefront measurements showed a higher total spherical aberration with a minimal pupil size of 4 mm in the Aspira group (0.05 ± 0.03 than in the Tecnis group (0.03 ± 0.02 (p=0.001. Strehl ratio was higher in eyes with Tecnis (0.28 ± 0.17 with a minimal pupil size larger than 5 mm than that with Aspira (0.16 ± 0.14 (p=0.04. In pupils with a minimum diameter of 4 mm spherical aberration had a significant effect on Strehl ratio, but not in pupils with a diameter less than 4 mm. Conclusions. Optical quality was better in eyes with the aberration-correcting Tecnis IOL when pupils were large. In contrast, this could not be shown in eyes with pupils under 4 mm or larger. This trial is registered with Clinicaltrials.gov NCT03224728.

  15. Research on the processing technology of medium-caliber aspheric lens in the optoelectronic integrated test system

    Science.gov (United States)

    Liu, Dan; Yu, Xin-ying; Wang, Wei

    2016-10-01

    In the optoelectronic integrated test system, surface profile and finish of the optical element are put forward higher request. Taking an aspherical quartz glass lens with a diameter of 200mm as example, taking Preston hypothesis as the theoretical basis, analyze the influence of surface quality of various process parameters, including the workpiece and the tool axis spindle speed, wheel type, concentration polishing, polishing mold species, dwell time, polishing pressure and other parameters. Using CNC method for the surface profile and surface quality of the lens were investigated. Taking profilometer measurement results as a guide, by testing and simulation analysis, process parameters were improved constantly in the process of manufacturing. Mid and high frequency error were trimmed and improved so that the surface form gradually converged to the required accuracy. The experimental results show that the final accuracy of the surface is less than 2µm and the surface finish is, which fulfils the accuracy requirement of aspherical focusing lens in optical system.

  16. A normal mode treatment of semi-diurnal body tides on an aspherical, rotating and anelastic Earth

    Science.gov (United States)

    Lau, Harriet C. P.; Yang, Hsin-Ying; Tromp, Jeroen; Mitrovica, Jerry X.; Latychev, Konstantin; Al-Attar, David

    2015-08-01

    Normal mode treatments of the Earth's body tide response were developed in the 1980s to account for the effects of Earth rotation, ellipticity, anelasticity and resonant excitation within the diurnal band. Recent space-geodetic measurements of the Earth's crustal displacement in response to luni-solar tidal forcings have revealed geographical variations that are indicative of aspherical deep mantle structure, thus providing a novel data set for constraining deep mantle elastic and density structure. In light of this, we make use of advances in seismic free oscillation literature to develop a new, generalized normal mode theory for the tidal response within the semi-diurnal and long-period tidal band. Our theory involves a perturbation method that permits an efficient calculation of the impact of aspherical structure on the tidal response. In addition, we introduce a normal mode treatment of anelasticity that is distinct from both earlier work in body tides and the approach adopted in free oscillation seismology. We present several simple numerical applications of the new theory. First, we compute the tidal response of a spherically symmetric, non-rotating, elastic and isotropic Earth model and demonstrate that our predictions match those based on standard Love number theory. Second, we compute perturbations to this response associated with mantle anelasticity and demonstrate that the usual set of seismic modes adopted for this purpose must be augmented by a family of relaxation modes to accurately capture the full effect of anelasticity on the body tide response. Finally, we explore aspherical effects including rotation and we benchmark results from several illustrative case studies of aspherical Earth structure against independent finite-volume numerical calculations of the semi-diurnal body tide response. These tests confirm the accuracy of the normal mode methodology to at least the level of numerical error in the finite-volume predictions. They also demonstrate

  17. Aspheric photorefractive keratectomy for myopia and myopic astigmatism with the SCHWIND AMARIS laser: 2 years postoperative outcomes

    Science.gov (United States)

    Aslanides, Ioannis M.; Padroni, Sara; Arba-Mosquera, Samuel

    2012-01-01

    Purpose To evaluate mid-term refractive outcomes and higher order aberrations of aspheric PRK for low, moderate and high myopia and myopic astigmatism with the AMARIS excimer laser system (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Methods This prospective longitudinal study evaluated 80 eyes of 40 subjects who underwent aspheric PRK. Manifest refractive spherical equivalent (MRSE) of up to −10.00 diopters (D) at the spectacle plane with cylinder up to 3.25 was treated. Refractive outcomes and corneal wavefront data (6 mm pupil to the 7th Zernike order) were evaluated out to 2 years postoperatively. Statistical significance was indicated by P  0.05, both cases). There was a statistical increase in postoperative coma (+0.12 μm) and spherical aberration (+0.14 μm) compared to preoperatively (P < 0.001, both cases). Conclusion Aspheric PRK provides excellent visual and refractive outcomes with induction in individual corneal aberrations but not overall corneal aberrations.

  18. Application of diffractive aspheric multifocal intraocular lens in the Uighur in phacoemulsification

    Directory of Open Access Journals (Sweden)

    Nuersimanguli·Mijiti

    2016-05-01

    Full Text Available AIM:To research the efficacy and safety of diffractive aspheric multifocal intraocular lens(MIOLin the Uighur in phacoemulsification to provide guidance for the clinical treatment of cataracts patients in Xinjiang region. METHODS:Two hundred and twenty-eight Uygur patients(280 eyesreceived phacoemulsification from April 2012 to March 2013 were randomly divided into multifocal group(106 cases with 146 eyesand monofocal group(122 cases with 134 eyes. Patients were followed up for 3mo. The intraocular pressure(IOP, uncorrected distance visual acuity, uncorrected near vision, best-corrected distance visual acuity and best corrected near vision were measured. The delensed rate, visual quality, and satisfaction for lenses in the form of questionnaires were compared. RESULTS:Multifocal group was better on the uncorrected near vision than monofocal group(PP>0.05. The contrast sensitivity of multifocal group under scotopia at spatial frequency 3c/d was lower than that of monofocal group(PP>0.05. Delensed rate of multifocal group was higher than that of monofocal group(PP>0.05.CONCLUSION:MIOL with phacoemulsification can provide patient good full range vision, especially on good near vision. The patients with MIOL implanted have a higher delensed rate, less postoperative adverse symptoms, quicker recovery and satisfaction.

  19. Production of {sup 44}Ti in neutrino-driven aspherical supernova explosions

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Shin-ichiro [Kumamoto National College of Technology, 2659-2 Suya, Goshi 861-1102 (Japan); Ono, Masaomi; Hashimoto, Masa-aki [Department of Physics, School of Sciences, Kyushu University, Fukuoka 810-8560 (Japan); Kotake, Kei [National Astronomical Observatory Japan, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan)

    2014-05-02

    We examine the synthesis of {sup 44}Ti in a neutrino-driven aspherical supernova (SN), focusing on reaction rates related to {sup 44}Ti and rotation of a progenitor. We have performed 2D hydrodynamic simulations of SN of a 15M{sub ⊙} progenitor, whose angular velocity is manually set to be a cylindrical distribution and have followed explosive nucleosynthesis in the ejecta. We find that the faster rates of {sup 40}Ca(α,γ){sup 44}Ti and the slower rate of {sup 44}Ti(α,p){sup 47}V lead to more massive ejection of {sup 44}Ti and {sup 56}Ni and larger ratios <{sup 44}Ti/{sup 56}Ni>. Faster rotation also results in more massive ejection of {sup 44}Ti and {sup 56}Ni. Ratios <{sup 44}Ti/{sup 56}Ni> are however independent from rotation. Large masses of {sup 44}Ti and large ratios observed in SN 1987A and Cas A (> 1O{sup −4}M{sub ⊙} and 1-2 respectively) are not realized in all the models.

  20. AxiSEM3D: broadband seismic wavefields in 3-D aspherical Earth models

    Science.gov (United States)

    Leng, K.; Nissen-Meyer, T.; Zad, K. H.; van Driel, M.; Al-Attar, D.

    2017-12-01

    Seismology is the primary tool for data-informed inference of Earth structure and dynamics. Simulating seismic wave propagation at a global scale is fundamental to seismology, but remains as one of most challenging problems in scientific computing, because of both the multiscale nature of Earth's interior and the observable frequency band of seismic data. We present a novel numerical method to simulate global seismic wave propagation in realistic 3-D Earth models. Our method, named AxiSEM3D, is a hybrid of spectral element method and pseudospectral method. It reduces the azimuthal dimension of wavefields by means of a global Fourier series parameterization, of which the number of terms can be locally adapted to the inherent azimuthal smoothness of the wavefields. AxiSEM3D allows not only for material heterogeneities, such as velocity, density, anisotropy and attenuation, but also for finite undulations on radial discontinuities, both solid-solid and solid-fluid, and thereby a variety of aspherical Earth features such as ellipticity, topography, variable crustal thickness, and core-mantle boundary topography. Such interface undulations are equivalently interpreted as material perturbations of the contiguous media, based on the "particle relabelling transformation". Efficiency comparisons show that AxiSEM3D can be 1 to 3 orders of magnitude faster than conventional 3-D methods, with the speedup increasing with simulation frequency and decreasing with model complexity, but for all realistic structures the speedup remains at least one order of magnitude. The observable frequency range of global seismic data (up to 1 Hz) has been covered for wavefield modelling upon a 3-D Earth model with reasonable computing resources. We show an application of surface wave modelling within a state-of-the-art global crustal model (Crust1.0), with the synthetics compared to real data. The high-performance C++ code is released at github.com/AxiSEM3D/AxiSEM3D.

  1. Corneal Epithelial Remodeling and Its Effect on Corneal Asphericity after Transepithelial Photorefractive Keratectomy for Myopia

    Directory of Open Access Journals (Sweden)

    Jie Hou

    2016-01-01

    Full Text Available Purpose. To evaluate the changes in epithelial thickness profile following transepithelial photorefractive keratectomy (T-PRK for myopia and to investigate the effect of epithelial remodeling on corneal asphericity. Methods. Forty-four patients (44 right eyes who underwent T-PRK were retrospectively evaluated. Epithelial thickness was measured using spectral-domain optical coherence tomography at different corneal zones (central, 2 mm; paracentral, 2–5 mm; and mid-peripheral, 5-6 mm preoperatively and at 1 week and 1, 3, and 6 months postoperatively. The correlation between the changes in corneal epithelial thickness (ΔCET and postoperative Q-value changes (ΔQ was analyzed 6 months postoperatively. Results. Epithelial thickness at 6 months showed a negative meniscus-like lenticular pattern with less central thickening, which increased progressively toward the mid-periphery (3.69±4.2, 5.19±3.8, and 6.23±3.9 μm at the center, paracenter, and mid-periphery, resp., P<0.01. A significant positive relationship was observed between epithelial thickening and ΔQ 6 months postoperatively (r=0.438, 0.580, and 0.504, resp., P<0.01. Conclusions. Significant epithelial thickening was observed after T-PRK and showed a lenticular change with more thickening mid-peripherally, resulting in increased oblateness postoperatively. Epithelial remodeling may modify the epithelial thickness profile after surface ablation refractive surgery for myopia.

  2. Mesopic visual quality after three kinds of aspheric acrylic monofocal intraocular lenses

    Directory of Open Access Journals (Sweden)

    Hai-Lun Ji

    2013-08-01

    Full Text Available AIM:To evaluate best corrected visual acuity(BCVAand contrast sensitivity(CSunder mesopic condition with no glare in patients following implantation of three different kinds of aspheric acrylic monofocal intraocular lens(IOLs.METHODS: Seventy-seven cases(90 eyesof age-related cataract patients were selected, who were undergone phacoemulsification and intraocular lens(IOLimplantation in our hospital during December 2011 to November 2012. Preoperatively, the patients were randomly divided into three groups: 30 eyes(25 caseswere implanted with hydrophobic yellow-tinted acrylic(HOYAIOLs in group 1; 30 eyes(28 caseswith hydrophilic acrylic IOLs(Raynerin group 2; 30 eyes(24 caseswith hydrophilic acrylic surface heparin processing IOLs(XOin group 3. All eyes were evaluated at 1 month and 3 months postoperatively. The BCVA and CS under mesopic condition without glare were measured and underwent statistical analysis.RESULTS: There was neither statistically significant difference in the BCVA(P>0.05, nor statistically significant difference in CS results(after standardization of contrast sensitivity value: lgCS(P>0.05between groups under mesopic condition, but the lgCS of the HOYA group decreased slightly. CONCLUSION: There were not marked differences of BCVA and CS between groups of patients at the follow-up intervals of 1 month and 3 months under mesopic condition. The blue-filter type artificial lens may protect the retina, thus, it is advisable to implant yellow-tinted filter blue artificial lens, especially for patients who are children or young persons.

  3. Clinical Evaluation of Functional Vision of +1.5 Diopters near Addition, Aspheric, Rotational Asymmetric Multifocal Intraocular Lens.

    Science.gov (United States)

    Kretz, Florian Tobias Alwin; Khoramnia, Rahmin; Attia, Mary Safwat; Koss, Michael Janusz; Linz, Katharina; Auffarth, Gerd Uwe

    2016-10-01

    To evaluate postoperative outcomes and visual performance in intermediate distance after implantation of a +1.5 diopters (D) addition, aspheric, rotational asymmetric multifocal intraocular lens (MIOL). Patients underwent bilateral cataract surgery with implantation of an aspheric, asymmetric MIOL with +1.5 D near addition. A complete ophthalmological examination was performed preoperatively and 3 months postoperatively. The main outcome measures were monocular and binocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA) and distance corrected keratometry, and manifest refraction. The Salzburg Reading Desk was used to analyze unilateral and bilateral functional vision with uncorrected and corrected reading acuity, reading distance, reading speed, and the smallest log-scaled print size that could be read effectively at near and intermediate distances. The study comprised 60 eyes of 30 patients (mean age, 68.30 ± 9.26 years; range, 34 to 80 years). There was significant improvement in UDVA and CDVA. Mean UIVA was 0.01 ± 0.09 logarithm of the minimum angle of resolution (logMAR) and mean DCIVA was -0.02 ± 0.11 logMAR. In Salzburg Reading Desk analysis for UIVA, the mean subjective intermediate distance was 67.58 ± 8.59 cm with mean UIVA of -0.02 ± 0.09 logMAR and mean word count of 96.38 ± 28.32 words/min. The new aspheric, asymmetric, +1.5 D near addition MIOL offers good results for distance visual function in combination with good performance for intermediate distances and functional results for near distance.

  4. Correlations between the alpha angle and femoral head asphericity: Implications and recommendations for the diagnosis of cam femoroacetabular impingement

    International Nuclear Information System (INIS)

    Harris, Michael D.; Kapron, Ashley L.; Peters, Christopher L.; Anderson, Andrew E.

    2014-01-01

    Objective: To determine the strength of common radiographic and radial CT views for measuring true femoral head asphericity. Patients and methods: In 15 patients with cam femoroacetabular impingement (FAI) and 15 controls, alpha angles were measured by two observers using radial CT (0°, 30°, 60°, 90°) and digitally reconstructed radiographs (DRRs) for the: anterior–posterior (AP), standing frog-leg lateral, 45° Dunn with neutral rotation, 45° Dunn with 40° external rotation, and cross-table lateral views. A DRR validation study was performed. Alpha angles were compared between groups. Maximum deviation from a sphere of each subject was obtained from a previous study. Alpha angles from each view were correlated with maximum deviation. Results: There were no significant differences between alpha angles measured on radiographs and the corresponding DRRs (p = 0.72). Alpha angles were significantly greater in patients for all views (p ≤ 0.002). Alpha angles from the 45° Dunn with 40° external rotation, cross-table lateral, and 60° radial views had the strongest correlations with maximum deviation (r = 0.831; r = 0.823; r = 0.808, respectively). The AP view had the weakest correlation (r = 0.358). Conclusion: DRRs were a validated means to simulate hip radiographs. The 45° Dunn with 40° external rotation, cross-table lateral, and 60° radial views best visualized femoral asphericity. Although commonly used, the AP view did not visualize cam deformities well. Overall, the magnitude of the alpha angle may not be indicative of the size of the deformity. Thus, 3D reconstructions and measurements of asphericity could improve the diagnosis of cam FAI

  5. Research on fabrication of aspheres at the Center of Optics Technology (University of Applied Science in Aalen); Techical Digest

    Science.gov (United States)

    Boerret, Rainer; Burger, Jochen; Bich, Andreas; Gall, Christoph; Hellmuth, Thomas

    2005-05-01

    The Center of Optics Technology at the University of Applied Science, founded in 2003, is part of the School of Optics and Mechatronics. It completes the existing optical engineering department with a full optical fabrication and metrology chain and serves in parallel as a technology transfer center, to provide area industries with the most up-to-date technology in optical fabrication and engineering. Two examples of research work will be presented. The first example is the optimizing of the grinding process for high precision aspheres, the other is generating and polishing of a freeform optical element which is used as a phase plate.

  6. REVIVAL OF THE STALLED CORE-COLLAPSE SUPERNOVA SHOCK TRIGGERED BY PRECOLLAPSE ASPHERICITY IN THE PROGENITOR STAR

    International Nuclear Information System (INIS)

    Couch, Sean M.; Ott, Christian D.

    2013-01-01

    Multi-dimensional simulations of advanced nuclear burning stages of massive stars suggest that the Si/O layers of presupernova stars harbor large deviations from the spherical symmetry typically assumed for presupernova stellar structure. We carry out three-dimensional core-collapse supernova simulations with and without aspherical velocity perturbations to assess their potential impact on the supernova hydrodynamics in the stalled-shock phase. Our results show that realistic perturbations can qualitatively alter the postbounce evolution, triggering an explosion in a model that fails to explode without them. This finding underlines the need for a multi-dimensional treatment of the presupernova stage of stellar evolution

  7. REVIVAL OF THE STALLED CORE-COLLAPSE SUPERNOVA SHOCK TRIGGERED BY PRECOLLAPSE ASPHERICITY IN THE PROGENITOR STAR

    Energy Technology Data Exchange (ETDEWEB)

    Couch, Sean M. [Flash Center for Computational Science, Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Ott, Christian D., E-mail: smc@flash.uchichago.edu, E-mail: cott@tapir.caltech.edu [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-11-20

    Multi-dimensional simulations of advanced nuclear burning stages of massive stars suggest that the Si/O layers of presupernova stars harbor large deviations from the spherical symmetry typically assumed for presupernova stellar structure. We carry out three-dimensional core-collapse supernova simulations with and without aspherical velocity perturbations to assess their potential impact on the supernova hydrodynamics in the stalled-shock phase. Our results show that realistic perturbations can qualitatively alter the postbounce evolution, triggering an explosion in a model that fails to explode without them. This finding underlines the need for a multi-dimensional treatment of the presupernova stage of stellar evolution.

  8. Optical methods for the optimization of system SWaP-C using aspheric components and advanced optical polymers

    Science.gov (United States)

    Zelazny, Amy; Benson, Robert; Deegan, John; Walsh, Ken; Schmidt, W. David; Howe, Russell

    2013-06-01

    We describe the benefits to camera system SWaP-C associated with the use of aspheric molded glasses and optical polymers in the design and manufacture of optical components and elements. Both camera objectives and display eyepieces, typical for night vision man-portable EO/IR systems, are explored. We discuss optical trade-offs, system performance, and cost reductions associated with this approach in both visible and non-visible wavebands, specifically NIR and LWIR. Example optical models are presented, studied, and traded using this approach.

  9. Dynamic correction of the laser beam coordinate in fabrication of large-sized diffractive elements for testing aspherical mirrors

    Science.gov (United States)

    Shimansky, R. V.; Poleshchuk, A. G.; Korolkov, V. P.; Cherkashin, V. V.

    2017-05-01

    This paper presents a method of improving the accuracy of a circular laser system in fabrication of large-diameter diffractive optical elements by means of a polar coordinate system and the results of their use. An algorithm for correcting positioning errors of a circular laser writing system developed at the Institute of Automation and Electrometry, SB RAS, is proposed and tested. Highprecision synthesized holograms fabricated by this method and the results of using these elements for testing the 6.5 m diameter aspheric mirror of the James Webb space telescope (JWST) are described..

  10. A lab-on-phone instrument with varifocal microscope via a liquid-actuated aspheric lens (LAL)

    Science.gov (United States)

    Fuh, Yiin-Kuen; Lai, Zheng-Hong; Kau, Li-Han; Huang, Hung-Jui

    2017-01-01

    In this paper, we introduce a novel concept of liquid-actuated aspheric lens (LAL) with a built-in aspheric polydimethylsiloxane lens (APL) to enable the design of compact optical systems with varifocal microscopic imaging. The varifocal lens module consists of a sandwiched structures such as 3d printed syringe pump functionally serves as liquid controller. Other key components include two acrylic cylinders, a rigid separator, a APL/membrane composite (APLMC) embedded PDMS membrane. In functional operation, the fluidic controller was driven to control the pressure difference and ALPMC deformation. The focal length can be changed through the pressure difference. This is achieved by the adjustment of volume change of injected liquid such that a widely tunable focal length. The proposed LAL can transform to 3 modes: microscopic mode (APLMC only), convex-concave mode and biconcave mode. It is noticeable that LAL in the operation of microscopic mode is tunable in focus via the actuation of APLMC (focal length is from 4.3 to 2.3 mm and magnification 50X) and can rival the images quality of commercial microscopes. A new lab-on-phone device is economically feasible and functionally versatile to offer a great potential in the point of care applications. PMID:28650971

  11. Minimization of variation in volumetric shrinkage and deflection on injection molding of Bi-aspheric lens using numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bensingh, R. Joseph [Central Institute of Plastics Engineering and Technology, Chennai (India); Boopathy, S. Rajendra [College of Engineering, Anna University, Chennai (India); Jebaraj, C. [Vellore Institutes of Technology, Chennai (India)

    2016-11-15

    The profile of a bi-aspheric lens is such a way that the thickness narrows down from center to periphery (convex). Injection molding of these profiles has high shrinkage in localized areas, which results in internal voids or sink marks when the part gets cool down to room temperature. This paper deals with the influence of injection molding process parameters such as mold surface temperature, melt temperature, injection time, V/P Switch over by percentage volume filled, packing pressure, and packing duration on the volumetric shrinkage and deflection. The optimal molding parameters for minimum variation in volumetric shrinkage and deflection of bi-aspheric lens have been determined with the application of computer numerical simulation integrated with optimization. The real experimental work carried out with optimal molding parameters and found to have a shallow and steep surface profile accuracy of 0.14 and 1.57 mm, 21.38-45.66 and 12.28-26.90 μm, 41.56-157.33 and 41.56-157.33 nm towards Radii of curvatures (RoC), surface roughness (Ra) and waviness of the surface profiles (profile error Pt), respectively.

  12. The asphericity of the metabolic tumour volume in NSCLC: correlation with histopathology and molecular markers

    International Nuclear Information System (INIS)

    Apostolova, Ivayla; Ego, Kilian; Steffen, Ingo G.; Buchert, Ralph; Wertzel, Heinz; Achenbach, H.J.; Riedel, Sandra; Schreiber, Jens; Schultz, Meinald; Furth, Christian; Amthauer, Holger; Derlin, Thorsten; Hofheinz, Frank; Kalinski, Thomas

    2016-01-01

    Asphericity (ASP) is a tumour shape descriptor based on the PET image. It quantitates the deviation from spherical of the shape of the metabolic tumour volume (MTV). In order to identify its biological correlates, we investigated the relationship between ASP and clinically relevant histopathological and molecular signatures in non-small-cell lung cancer (NSCLC). The study included 83 consecutive patients (18 women, aged 66.4 ± 8.9 years) with newly diagnosed NSCLC in whom PET/CT with 18 F-FDG had been performed prior to therapy. Primary tumour resection specimens and core biopsies were used for basic histopathology and determination of the Ki-67 proliferation index. EGFR status, VEGF, p53 and ALK expression were obtained in a subgroup of 44 patients. The FDG PET images of the primary tumours were delineated using an automatic algorithm based on adaptive thresholding taking into account local background. In addition to ASP, SUVmax, MTV and some further descriptors of shape and intratumour heterogeneity were assessed as semiquantitative PET measures. SUVmax, MTV and ASP were associated with pathological T stage (Kruskal-Wallis, p = 0.001, p < 0.0005 and p < 0.0005, respectively) and N stage (p = 0.017, p = 0.003 and p = 0.002, respectively). Only ASP was associated with M stage (p = 0.026). SUVmax, MTV and ASP were correlated with Ki-67 index (Spearman's rho = 0.326/p = 0.003, rho = 0.302/p = 0.006 and rho = 0.271/p = 0.015, respectively). The latter correlations were considerably stronger in adenocarcinomas than in squamous cell carcinomas. ASP, but not SUVmax or MTV, showed a tendency for a significant association with the extent of VEGF expression (p = 0.058). In multivariate Cox regression analysis, ASP (p < 0.0005) and the presence of distant metastases (p = 0.023) were significantly associated with progression-free survival. ASP (p = 0.006), the presence of distant metastases (p = 0.010), and Ki-67 index (p = 0.062) were significantly associated with

  13. Computer numerically controlled (CNC) aspheric shaping with toroidal Wheels (Abstract Only)

    Science.gov (United States)

    Ketelsen, D.; Kittrell, W. C.; Kuhn, W. M.; Parks, R. E.; Lamb, George L.; Baker, Lynn

    1987-01-01

    Contouring with computer numerically controlled (CNC) machines can be accomplished with several different tool geometries and coordinated machine axes. To minimize the number of coordinated axes for nonsymmetric work to three, it is common practice to use a spherically shaped tool such as a ball-end mill. However, to minimize grooving due to the feed and ball radius, it is desirable to use a long ball radius, but there is clearly a practical limit to ball diameter with the spherical tool. We have found that the use of commercially available toroidal wheels permits long effective cutting radii, which in turn improve finish and minimize grooving for a set feed. In addition, toroidal wheels are easier than spherical wheels to center accurately. Cutting parameters are also easier to control because the feed rate past the tool does not change as the slope of the work changes. The drawback to the toroidal wheel is the more complex calculation of the tool path. Of course, once the algorithm is worked out, the tool path is as easily calculated as for a spherical tool. We have performed two experiments with the Large Optical Generator (LOG) that were ideally suited to three-axis contouring--surfaces that have no axis of rotational symmetry. By oscillating the cutting head horizontally or vertically (in addition to the motions required to generate the power of the surface) , and carefully coordinating those motions with table rotation, the mostly astigmatic departure for these surfaces is produced. The first experiment was a pair of reflector molds that together correct the spherical aberration of the Arecibo radio telescope. The larger of these was 5 m in diameter and had a 12 cm departure from the best-fit sphere. The second experiment was the generation of a purely astigmatic surface to demonstrate the feasibility of producing axially symmetric asphe.rics while mounted and rotated about any off-axis point. Measurements of the latter (the first experiment had relatively

  14. The asphericity of the metabolic tumour volume in NSCLC: correlation with histopathology and molecular markers

    Energy Technology Data Exchange (ETDEWEB)

    Apostolova, Ivayla; Ego, Kilian; Steffen, Ingo G. [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Radiology and Nuclear Medicine, Magdeburg (Germany); Buchert, Ralph [University Medicine Charite, Clinic of Nuclear Medicine, Berlin (Germany); Wertzel, Heinz; Achenbach, H.J. [Lung Clinic Lostau GmbH, Lostau (Germany); Riedel, Sandra; Schreiber, Jens [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Pneumology, Magdeburg (Germany); Schultz, Meinald [Institute of Pathology Stendal, Stendal (Germany); Furth, Christian; Amthauer, Holger [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Radiology and Nuclear Medicine, Magdeburg (Germany); University Medicine Charite, Clinic of Nuclear Medicine, Berlin (Germany); Derlin, Thorsten [Hannover Medical School, Department of Nuclear Medicine, Hannover (Germany); Hofheinz, Frank [Helmholtz-Center Dresden-Rossendorf, Dresden (Germany); Kalinski, Thomas [University Hospital Magdeburg, Otto-von-Guericke University Magdeburg, Institute for Pathology, Magdeburg (Germany); Institute for Pathology Lademannbogen, Hamburg (Germany)

    2016-12-15

    Asphericity (ASP) is a tumour shape descriptor based on the PET image. It quantitates the deviation from spherical of the shape of the metabolic tumour volume (MTV). In order to identify its biological correlates, we investigated the relationship between ASP and clinically relevant histopathological and molecular signatures in non-small-cell lung cancer (NSCLC). The study included 83 consecutive patients (18 women, aged 66.4 ± 8.9 years) with newly diagnosed NSCLC in whom PET/CT with {sup 18}F-FDG had been performed prior to therapy. Primary tumour resection specimens and core biopsies were used for basic histopathology and determination of the Ki-67 proliferation index. EGFR status, VEGF, p53 and ALK expression were obtained in a subgroup of 44 patients. The FDG PET images of the primary tumours were delineated using an automatic algorithm based on adaptive thresholding taking into account local background. In addition to ASP, SUVmax, MTV and some further descriptors of shape and intratumour heterogeneity were assessed as semiquantitative PET measures. SUVmax, MTV and ASP were associated with pathological T stage (Kruskal-Wallis, p = 0.001, p < 0.0005 and p < 0.0005, respectively) and N stage (p = 0.017, p = 0.003 and p = 0.002, respectively). Only ASP was associated with M stage (p = 0.026). SUVmax, MTV and ASP were correlated with Ki-67 index (Spearman's rho = 0.326/p = 0.003, rho = 0.302/p = 0.006 and rho = 0.271/p = 0.015, respectively). The latter correlations were considerably stronger in adenocarcinomas than in squamous cell carcinomas. ASP, but not SUVmax or MTV, showed a tendency for a significant association with the extent of VEGF expression (p = 0.058). In multivariate Cox regression analysis, ASP (p < 0.0005) and the presence of distant metastases (p = 0.023) were significantly associated with progression-free survival. ASP (p = 0.006), the presence of distant metastases (p = 0.010), and Ki-67 index (p = 0.062) were significantly associated with

  15. Reading performance of monofocal pseudophakic patients with and without glasses under normal and dim light conditions.

    Science.gov (United States)

    Radner, Wolfgang; Radner, Stephan; Raunig, Valerian; Diendorfer, Gabriela

    2014-03-01

    To evaluate reading performance of patients with monofocal intraocular lenses (IOLs) (Acrysof SN60WF) with or without reading glasses under bright and dim light conditions. Austrian Academy of Ophthalmology, Vienna, Austria. Evaluation of a diagnostic test or technology. In pseudophakic patients, the spherical refractive error was limited to between +0.50 diopter (D) and -0.75 D with astigmatism of 0.75 D (mean spherical equivalent: right eye, -0.08 ± 0.43 [SD]; left eye, -0.15 ± 0.35). Near addition was +2.75 D. Reading performance was assessed binocularly with or without reading glasses at an illumination of 100 candelas (cd)/m(2) and 4 cd/m(2) using the Radner Reading Charts. In the 25 patients evaluated, binocularly, the mean corrected distance visual acuity was -0.07 ± 0.06 logMAR and the mean uncorrected distance visual acuity was 0.01 ± 0.11 logMAR. The mean reading acuity with reading glasses was 0.02 ± 0.10 logRAD at 100 cd/m(2) and 0.12 ± 0.14 logRAD at 4 cd/m(2). Without reading glasses, it was 0.44 ± 0.13 logRAD and 0.56 ± 0.16 logRAD, respectively (P light conditions. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  16. MATTER MIXING IN ASPHERICAL CORE-COLLAPSE SUPERNOVAE: A SEARCH FOR POSSIBLE CONDITIONS FOR CONVEYING {sup 56}Ni INTO HIGH VELOCITY REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masaomi; Nagataki, Shigehiro; Ito, Hirotaka; Lee, Shiu-Hang; Mao, Jirong; Tolstov, Alexey [Astrophysical Big Bang Laboratory, RIKEN, Saitama 351-0198 (Japan); Hashimoto, Masa-aki, E-mail: masaomi.ono@riken.jp [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan)

    2013-08-20

    We perform two-dimensional axisymmetric hydrodynamic simulations of matter mixing in aspherical core-collapse supernova explosions of a 16.3 M{sub Sun} star with a compact hydrogen envelope. Observations of SN 1987A have provided evidence that {sup 56}Ni synthesized by explosive nucleosynthesis is mixed into fast moving matter ({approx}>3500 km s{sup -1}) in the exploding star. In order to clarify the key conditions for reproducing such high velocity of {sup 56}Ni, we revisit matter mixing in aspherical core-collapse supernova explosions. Explosions are initiated artificially by injecting thermal and kinetic energies around the interface between the iron core and the silicon-rich layer. Perturbations of 5% or 30% amplitude in the radial velocities are introduced at several points in time. We find that no high velocity {sup 56}Ni can be obtained if we consider bipolar explosions with perturbations (5% amplitude) of pre-supernova origins. If large perturbations (30% amplitude) are introduced or exist due to some unknown mechanism in a later phase just before the shock wave reaches the hydrogen envelope, {sup 56}Ni with a velocity of 3000 km s{sup -1} can be obtained. Aspherical explosions that are asymmetric across the equatorial plane with clumpy structures in the initial shock waves are investigated. We find that the clump sizes affect the penetration of {sup 56}Ni. Finally, we report that an aspherical explosion model that is asymmetric across the equatorial plane with multiple perturbations of pre-supernova origins can cause the penetration of {sup 56}Ni clumps into fast moving matter of 3000 km s{sup -1}. We show that both aspherical explosions with clumpy structures and perturbations of pre-supernova origins may be necessary to reproduce the observed high velocity of {sup 56}Ni. To confirm this, more robust three-dimensional simulations are required.

  17. MATTER MIXING IN ASPHERICAL CORE-COLLAPSE SUPERNOVAE: A SEARCH FOR POSSIBLE CONDITIONS FOR CONVEYING 56Ni INTO HIGH VELOCITY REGIONS

    International Nuclear Information System (INIS)

    Ono, Masaomi; Nagataki, Shigehiro; Ito, Hirotaka; Lee, Shiu-Hang; Mao, Jirong; Tolstov, Alexey; Hashimoto, Masa-aki

    2013-01-01

    We perform two-dimensional axisymmetric hydrodynamic simulations of matter mixing in aspherical core-collapse supernova explosions of a 16.3 M ☉ star with a compact hydrogen envelope. Observations of SN 1987A have provided evidence that 56 Ni synthesized by explosive nucleosynthesis is mixed into fast moving matter (∼>3500 km s –1 ) in the exploding star. In order to clarify the key conditions for reproducing such high velocity of 56 Ni, we revisit matter mixing in aspherical core-collapse supernova explosions. Explosions are initiated artificially by injecting thermal and kinetic energies around the interface between the iron core and the silicon-rich layer. Perturbations of 5% or 30% amplitude in the radial velocities are introduced at several points in time. We find that no high velocity 56 Ni can be obtained if we consider bipolar explosions with perturbations (5% amplitude) of pre-supernova origins. If large perturbations (30% amplitude) are introduced or exist due to some unknown mechanism in a later phase just before the shock wave reaches the hydrogen envelope, 56 Ni with a velocity of 3000 km s –1 can be obtained. Aspherical explosions that are asymmetric across the equatorial plane with clumpy structures in the initial shock waves are investigated. We find that the clump sizes affect the penetration of 56 Ni. Finally, we report that an aspherical explosion model that is asymmetric across the equatorial plane with multiple perturbations of pre-supernova origins can cause the penetration of 56 Ni clumps into fast moving matter of 3000 km s –1 . We show that both aspherical explosions with clumpy structures and perturbations of pre-supernova origins may be necessary to reproduce the observed high velocity of 56 Ni. To confirm this, more robust three-dimensional simulations are required

  18. High-Speed 3D Printing of Millimeter-Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness.

    Science.gov (United States)

    Chen, Xiangfan; Liu, Wenzhong; Dong, Biqin; Lee, Jongwoo; Ware, Henry Oliver T; Zhang, Hao F; Sun, Cheng

    2018-05-01

    Advancements in three-dimensional (3D) printing technology have the potential to transform the manufacture of customized optical elements, which today relies heavily on time-consuming and costly polishing and grinding processes. However the inherent speed-accuracy trade-off seriously constrains the practical applications of 3D-printing technology in the optical realm. In addressing this issue, here, a new method featuring a significantly faster fabrication speed, at 24.54 mm 3 h -1 , without compromising the fabrication accuracy required to 3D-print customized optical components is reported. A high-speed 3D-printing process with subvoxel-scale precision (sub 5 µm) and deep subwavelength (sub 7 nm) surface roughness by employing the projection micro-stereolithography process and the synergistic effects from grayscale photopolymerization and the meniscus equilibrium post-curing methods is demonstrated. Fabricating a customized aspheric lens 5 mm in height and 3 mm in diameter is accomplished in four hours. The 3D-printed singlet aspheric lens demonstrates a maximal imaging resolution of 373.2 lp mm -1 with low field distortion less than 0.13% across a 2 mm field of view. This lens is attached onto a cell phone camera and the colorful fine details of a sunset moth's wing and the spot on a weevil's elytra are captured. This work demonstrates the potential of this method to rapidly prototype optical components or systems based on 3D printing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. ASPHERICITY, INTERACTION, AND DUST IN THE TYPE II-P/II-L SUPERNOVA 2013EJ IN MESSIER 74

    Energy Technology Data Exchange (ETDEWEB)

    Mauerhan, Jon C.; Graham, Melissa L.; Filippenko, Alexei V.; Shivvers, Isaac [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Van Dyk, Schuyler D. [Infrared Processing and Analysis Center, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States); Johansson, Joel [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 234 Herzl St., Rehovot (Israel); Hu, Maokai; Wang, Lifan [Department of Physics, Texas A and M University, College Station, TX 77843 (United States); Fox, Ori D., E-mail: mauerhan@astro.berkeley.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2017-01-10

    SN 2013ej is a well-studied core-collapse supernova (SN) that stemmed from a directly identified red supergiant (RSG) progenitor in galaxy M74. The source exhibits signs of substantial geometric asphericity, X-rays from persistent interaction with circumstellar material (CSM), thermal emission from warm dust, and a light curve that appears intermediate between supernovae of Types II-P and II-L. The proximity of this source motivates a close inspection of these physical characteristics and their potential interconnection. We present multiepoch spectropolarimetry of SN 2013ej during the first 107 days and deep optical spectroscopy and ultraviolet through infrared photometry past ∼800 days. SN 2013ej exhibits the strongest and most persistent continuum and line polarization ever observed for a SN of its class during the recombination phase. Modeling indicates that the data are consistent with an oblate ellipsoidal photosphere, viewed nearly edge-on and probably augmented by optical scattering from circumstellar dust. We suggest that interaction with an equatorial distribution of CSM, perhaps the result of binary evolution, is responsible for generating the photospheric asphericity. Relatedly, our late-time optical imaging and spectroscopy show that asymmetric CSM interaction is ongoing, and the morphology of broad H α emission from shock-excited ejecta provides additional evidence that the geometry of the interaction region is ellipsoidal. Alternatively, a prolate ellipsoidal geometry from an intrinsically bipolar explosion is also a plausible interpretation of the data but would probably require a ballistic jet of radioactive material capable of penetrating the hydrogen envelope early in the recombination phase. Finally, our latest space-based optical imaging confirms that the late interaction-powered light curve dropped below the stellar progenitor level, confirming the RSG star’s association with the explosion.

  20. Preliminary study of the correlation between refractive error and corneal refractive power, corneal asphericity in myopic eye

    Directory of Open Access Journals (Sweden)

    Qi-Chao Han

    2014-05-01

    Full Text Available AIM: To investigate the correlation between myopic refractive error and relative factors, including the corneal refractive power, posterior refractive power, axial length, corneal asphericity coefficient Q value, central cornea thickness(CCTand intraocular pressure(IOP. METHODS:According to the degree of myopia measured by subjective refraction, 138 myopia patients were divided into three subgroups: mild group(-1.00D--3.00D, moderate group(-3.25D--6.00D, high group(>6.00D. The Pentacam anterior segment tomographer(Germany, Oculus Companywas used to measure the corneal refractive power, posterior refractive power, and corneal asphericity in the right eye. IOP, CCT and axial length were measured by a non-contact tonometer and A-scan ultrasonic, respectively. The data was analyzed with a Pearson correlation analysis and one-way ANOVA. RESULTS: The myopic refractive error was negatively correlated with the axial length(r=-0.682, Pr=0.009, P=0.925. The axial length was negatively correlated with corneal refractive power(r=-0.554, Pr=0.674, Pr=-0.375, P=0.01. There was no significantly correlation between the myopic refractive error and CCT, IOP(r=-0.138, P=0.141; r=-0.121, P=0.157. CONCLUSION:The corneal refractive power plays the role of emmetropization during the development of myopia. There is clinic significance for the correlation between Q value and refractive error, IOP to guide the corneal refractive surgery.

  1. Evaluation of optical performance of 4 aspheric toric intraocular lenses using an optical bench system: Influence of pupil size, decentration, and rotation.

    Science.gov (United States)

    Kim, Min-Ji; Yoo, Young-Sik; Joo, Choun-Ki; Yoon, Geunyoung

    2015-10-01

    To evaluate the effect of pupil size, degree of intraocular lens (IOL) decentration, and rotation of 4 aspheric toric IOLs on the image quality. Department of Ophthalmology, Seoul St. Mary's Hospital, Seoul, South Korea. Experimental study. Four aspheric toric intraocular lenses (IOLs)-the Precizon (transitional conic toric IOL), AT Torbi 709M (bitoric IOL), SN6AT4 (posterior toric surface IOL), and ZCT225 (anterior toric surface IOL)-were evaluated using the optical bench metrology system. Measurements included changes in spherical aberrations, relative spherical equivalent (SE), and image quality at different pupil diameters and image quality degradation due to decentration and rotation of the IOLs. Change in relative SE with pupil size in aberration-free toric IOLs (transitional conic toric and bitoric IOLs) was greater than in negatively aspheric toric IOLs (posterior toric surface and anterior toric surface IOLs). In contrast, the aberration-free IOLs showed higher contrast than the negatively aspheric IOLs. When IOLs were decentered by 1.0 mm, the contrast reduction rates at 17.6 cycles per degree for the transitional conic toric IOL, bitoric IOL, posterior toric surface IOL, and anterior toric surface IOL were 5.1%, 3.1%, 12.2%, and 15.8%, respectively. Rotation-induced deterioration of contrast to 0.5 required a much higher rotation for the transitional conic toric IOL than for the other 3 IOLs. The transitional conic toric IOL and bitoric IOL provided superior image quality despite pupil size changes and the presence of decentration. The transitional conic toric IOL demonstrated maximum rotation tolerance compared with the other IOLs. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  2. [Impact of an Aspherical Aberration Correcting Monofocal Intraocular Lens on Patient Satisfaction for Daily Life Activities: The Heidelberg Daily Task Evaluation (DATE) Questionnaire].

    Science.gov (United States)

    Kretz, F T A; Son, H; Liebing, S; Tandogan, T; Auffarth, G U

    2015-08-01

    A clinical evaluation of the functional results and its impact on daily activities of an aspherical, aberration correcting intraocular lens (IOL) was undertaken. Twenty-one patients aged from 50 to 83 years underwent cataract surgery with implantation of the aspheric IOL (Tecnis ZCB00, Abbott Medical Optics). They were evaluated 2 to 4 months after surgery for their subjective satisfaction of vision quality and its impact on performance of daily activities as well as functional results and refractive outcome. Patients were asked to fill out a questionnaire - the Heidelberg DATE (DAily Tasks Evaluation) questionnaire. Significant changes from pre- to postoperative results were found in refraction (p ≤ 0.03), with a mean prediction error of + 0.21 ± 0.43 D. UDVA and CDVA improved significantly (p < 0.01), with a postoperative CDVA of 0.0 logMAR or better in 97.1 % of eyes. All patients would recommend the procedure to a relative or a friend and 93.8 % of patients reported to be satisfied with the outcome. The implantation of the aspheric IOL Tecnis ZCB00 after cataract surgery allows the restoration of visual function, providing an optimised optical quality and a high level of patient satisfaction. Georg Thieme Verlag KG Stuttgart · New York.

  3. Visual Outcomes after Phacoemulsification with AcrySof Toric ...

    African Journals Online (AJOL)

    2016-12-13

    Dec 13, 2016 ... The mean axis of rotation was 2.76 ± 1.88° in all eyes. Ninety percent of ... Myopia and hyperopia can be corrected by .... antibiotic eye drops for 4–6 weeks. ..... Cavallini GM, Campi L, Masini C, Pelloni S, Pupino A. Bimanual.

  4. Aspherical-atom modeling of coordination compounds by single-crystal X-ray diffraction allows the correct metal atom to be identified.

    Science.gov (United States)

    Dittrich, Birger; Wandtke, Claudia M; Meents, Alke; Pröpper, Kevin; Mondal, Kartik Chandra; Samuel, Prinson P; Amin Sk, Nurul; Singh, Amit Pratap; Roesky, Herbert W; Sidhu, Navdeep

    2015-02-02

    Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Sensor-Based Inspection of the Formation Accuracy in Ultra-Precision Grinding (UPG) of Aspheric Surface Considering the Chatter Vibration

    Science.gov (United States)

    Lei, Yao; Bai, Yue; Xu, Zhijun

    2018-06-01

    This paper proposes an experimental approach for monitoring and inspection of the formation accuracy in ultra-precision grinding (UPG) with respect to the chatter vibration. Two factors related to the grinding progress, the grinding speed of grinding wheel and spindle, and the oil pressure of the hydrostatic bearing are taken into account to determining the accuracy. In the meantime, a mathematical model of the radius deviation caused by the micro vibration is also established and applied in the experiments. The results show that the accuracy is sensitive to the vibration and the forming accuracy is much improved with proper processing parameters. It is found that the accuracy of aspheric surface can be less than 4 μm when the grinding speed is 1400 r/min and the wheel speed is 100 r/min with the oil pressure being 1.1 MPa.

  6. Sensor-Based Inspection of the Formation Accuracy in Ultra-Precision Grinding (UPG) of Aspheric Surface Considering the Chatter Vibration

    Science.gov (United States)

    Lei, Yao; Bai, Yue; Xu, Zhijun

    2018-03-01

    This paper proposes an experimental approach for monitoring and inspection of the formation accuracy in ultra-precision grinding (UPG) with respect to the chatter vibration. Two factors related to the grinding progress, the grinding speed of grinding wheel and spindle, and the oil pressure of the hydrostatic bearing are taken into account to determining the accuracy. In the meantime, a mathematical model of the radius deviation caused by the micro vibration is also established and applied in the experiments. The results show that the accuracy is sensitive to the vibration and the forming accuracy is much improved with proper processing parameters. It is found that the accuracy of aspheric surface can be less than 4 μm when the grinding speed is 1400 r/min and the wheel speed is 100 r/min with the oil pressure being 1.1 MPa.

  7. Preliminary evaluation of an algorithm to minimize the power error selection of an aspheric intraocular lens by optimizing the estimation of the corneal power and the effective lens position

    Directory of Open Access Journals (Sweden)

    David P. Piñero

    2016-06-01

    Full Text Available AIM: To evaluate the refractive predictability achieved with an aspheric intraocular lens(IOLand to develop a preliminary optimized algorithm for the calculation of its power(PIOL.METHODS: This study included 65 eyes implanted with the aspheric IOL LENTIS L-313(Oculentis GmbHthat were divided into 2 groups: 12 eyes(8 patientswith PIOL≥23.0 D(group A, and 53 eyes(35 patientswith PIOLIOLadjwas calculated considering a variable refractive index for corneal power estimation, the refractive outcome obtained, and an adjusted effective lens position(ELPadjaccording to age and anatomical factors. RESULTS: Postoperative spherical equivalent ranged from -0.75 to +0.75 D and from -1.38 to +0.75 D in groups A and B, respectively. No statistically significant differences were found in groups A(P=0.64and B(P=0.82between PIOLadj and the IOL power implanted(PIOLReal. The Bland and Altman analysis showed ranges of agreement between PIOLadj and PIOLReal of +1.11 to -0.96 D and +1.14 to -1.18 D in groups A and B, respectively. Clinically and statistically significant differences were found between PIOLadj and PIOL obtained with Hoffer Q and Holladay I formulas(PCONCLUSION: The refractive predictability of cataract surgery with implantation of an aspheric IOL can be optimized using paraxial optics combined with linear algorithms to minimize the error associated to the estimation of corneal power and ELP.

  8. ANALYSIS OF THE RESULTS OF PRESBYOPIA CORRECTION WITH APPLICATION OF A BI-ASPHERIC MULTIFOCAL PROFILE ON THE CORNEA BY THE PRK FOR PATIENTS WITH MYOPIA AND HYPEROPIA

    Directory of Open Access Journals (Sweden)

    E. N. Eskina

    2017-01-01

    Full Text Available Purpose. To compare the efficacy, safety and predictability of presbyopia correction by the PRK with application of a bi-aspheric multifocal profile on the cornea with PresbyMax software for patients with hyperopia and myopia.Patients and methods: There were 2 patients group of 25 people each (50 eyes. They were operated with PRK method with application of a multifocal biaspheric profile for simultaneous correction of ametropia and presbyopia. Group I — patients with myopia and presbyopia. Group II — patients with hypermetropia and presbyopia.Results. In the group 1 year post operation binocular DUCVA was 0,93±0,19, NUCVA — 0,86±0,14, IUCVA — 0,67±0,11. Only two eyes (4 % lost DBCVA on the 1–2 lines. Target refraction of a dominant eye — emmetropia was 72 % of patients, 28 % observed myopia of –0,75 D. Target refraction of a nondominant eye was –0,75, 68 % had this result, 28 % had deviation –0,50 D of the target refraction, and 4 % — 1,00 D. In group 2 a year post operation binocular DUCVA was 0,96±0,16, NUCVA — 0,77±0,19, IUCVA — 0,64±0,15. Only two eyes (4 % lost DBCVA on the 1–2 lines. Target refraction of a dominant eye — emmetropia was 72 % of patients, 28 % observed myopia of –0,75 D. Target refraction of a nondominant eye was –0,75, 68 % had this result, 32 % had deviation to –0,75 D of the target refraction.Conclusions. PRK with application of a bi-aspheric multifocal profile on the cornea using PresbyMAX software and µ-monovision is effective for correction myopia and hypermetropia. Simultaneous correction of ametropia and presbyopia by the PRK method with the application of the multifocal biospheric profile to the cornea with the formation of a slight anisometropia (the concept of µ-monovision with the PresbyMax software is an effective, safe and predictable method of surgical intervention, both in myopia and hypermetropia.

  9. Combining crystallographic information and an aspherical-atom data bank in the evaluation of the electrostatic interaction energy in an enzyme–substrate complex: influenza neuraminidase inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Dominiak, Paulina M., E-mail: pdomin@chem.uw.edu.pl [Department of Chemistry, State University of New York at Buffalo, NY 14260 (United States); Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warszawa (Poland); Volkov, Anatoliy; Dominiak, Adam P. [Department of Chemistry, State University of New York at Buffalo, NY 14260 (United States); Jarzembska, Katarzyna N. [Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warszawa (Poland); Coppens, Philip, E-mail: pdomin@chem.uw.edu.pl [Department of Chemistry, State University of New York at Buffalo, NY 14260 (United States)

    2009-05-01

    The electrostatic component of the enzyme/inhibitor interaction of a wide range influenza neuraminidases and inhibitors has been analyzed using transferable aspherical-atom densities from a recently compiled databank. Results are subdivided into the contributions of individual active-site residues and different functional groups of the inhibitors, and the effect of the Arg292→Lys mutation is considered. Although electrostatic interactions contribute only a part of the interaction energies between macromolecules, unlike dispersion forces they are highly directional and therefore dominate the nature of molecular packing in crystals and in biological complexes and contribute significantly to differences in inhibition strength among related enzyme inhibitors. In the reported study, a wide range of complexes of influenza neuraminidases with inhibitor molecules (sialic acid derivatives and others) have been analyzed using charge densities from a transferable aspherical-atom data bank. The strongest interactions of the residues are with the acidic group at the C2 position of the inhibitor (∼−300 kJ mol{sup −1} for —COO{sup −} in non-aromatic inhibitors, ∼−120–210 kJ mol{sup −1} for —COO{sup −} in aromatic inhibitors and ∼−450 kJ mol{sup −1} for —PO{sub 3}{sup 2−}) and with the amino and guanidine groups at C4 (∼−250 kJ mol{sup −1}). Other groups contribute less than ∼100 kJ mol{sup −1}. Residues Glu119, Asp151, Glu227, Glu276 and Arg371 show the largest variation in electrostatic energies of interaction with different groups of inhibitors, which points to their important role in the inhibitor recognition. The Arg292→Lys mutation reduces the electrostatic interactions of the enzyme with the acidic group at C2 for all inhibitors that have been studied (SIA, DAN, 4AM, ZMR, G20, G28, G39 and BCZ), but enhances the interactions with the glycerol group at C6 for inhibitors that contain it. This is in agreement with the lower level

  10. Do blue-light filtering intraocular lenses affect visual function?

    Science.gov (United States)

    Lavric, Alenka; Pompe, Manca Tekavcic

    2014-11-01

    To study different aspects of visual function, macular changes, and subjective differences between the eye with an ultraviolet (UV) and blue-light filtering intraocular lens (IOL) and the fellow eye with a UV-light filtering IOL. Thirty patients (60 eyes) with senile cataract had both cataracts extracted, and an IOL was implanted at least 2 years before clinical evaluation. In one eye, AcrySof SA60AT (a UV-light filtering IOL) was implanted, whereas in the contralateral eye, AcrySof IQ SN60WF (a blue-light filtering IOL) was implanted. Each patient underwent visual acuity testing, color vision testing (Ishihara and Farnsworth-Munsell 100-hue tests), and contrast sensitivity (CS) testing. The macula was evaluated with optical coherence tomography and with clinical examination. Patients were asked if they noted any difference between the implanted IOLs concerning visual impression. Subjective visual quality was evaluated using the National Eye Institute Visual Functioning Questionnaire. There was a borderline statistically significant difference in the mean best-corrected visual acuity (p = 0.05). As regards color vision, no significant changes in Ishihara and Farnsworth-Munsell 100-hue error scores were detected between both eyes (p = 0.48 and p = 0.59, respectively). Analysis of CS showed no significant difference between the groups at any spatial frequency. There were also no statistically significant differences in central macular thickness and total macular volume between the two IOL groups (p = 0.72 and p = 0.61, respectively). In both IOL groups, three eyes developed an epiretinal membrane, and six eyes developed early signs of age-related macular degeneration. This study showed no significant effects of a blue-light filtering IOL on visual acuity and no influence on color perception and CS. After more than 2 years, there were no significant differences in macular changes between the IOL groups. Clinical evidence of the effect of a blue-light filtering IOL on

  11. Fabrication of Light Extraction Efficiency of Organic Light-Emitting Diodes with 3D Aspherical Microlens by Using Dry Etching Process

    Directory of Open Access Journals (Sweden)

    Y. C. Chen

    2013-01-01

    Full Text Available organic light-emitting diode (OLED can enable a greater artificial contrast ratio and viewing angle compared to liquid crystal display (LCD because OLED pixels directly emit light. There is a shortcoming that the internal quantum efficiency can reach values close to 100%, but about 80% light disperses because of the difference among the refractive indices of the substrate, anode, indium tin oxide (ITO film, and air. In this paper, three dimensions aspherical microlens arrays (3D A-MLAs with substrate modifications are developed to simulate the optical luminous field by using FRED software. This study modified parameters of 3D A-MLAs such as the diameter, fill-factor, aspect ratio, dry etching parameters, and electroforming rates of microlens to improve the extraction efficiency of the OLED. In dry etching, not only the aspect ratio with better extraction rate can be obtained by reactive ion etching (RIE dry etching, but also an undercutting phenomenon can be avoided. The dimensions of 3D A-MLAs can be accurately controlled in the electroforming process used to make a nickel-cobalt (Ni-Co metal mold to achieve the designed dimensions. According to the measured results, the average luminance efficacy of the OLEDs with 3D A-MLAs can be enhanced.

  12. DiSCaMB: a software library for aspherical atom model X-ray scattering factor calculations with CPUs and GPUs.

    Science.gov (United States)

    Chodkiewicz, Michał L; Migacz, Szymon; Rudnicki, Witold; Makal, Anna; Kalinowski, Jarosław A; Moriarty, Nigel W; Grosse-Kunstleve, Ralf W; Afonine, Pavel V; Adams, Paul D; Dominiak, Paulina Maria

    2018-02-01

    It has been recently established that the accuracy of structural parameters from X-ray refinement of crystal structures can be improved by using a bank of aspherical pseudoatoms instead of the classical spherical model of atomic form factors. This comes, however, at the cost of increased complexity of the underlying calculations. In order to facilitate the adoption of this more advanced electron density model by the broader community of crystallographers, a new software implementation called DiSCaMB , 'densities in structural chemistry and molecular biology', has been developed. It addresses the challenge of providing for high performance on modern computing architectures. With parallelization options for both multi-core processors and graphics processing units (using CUDA), the library features calculation of X-ray scattering factors and their derivatives with respect to structural parameters, gives access to intermediate steps of the scattering factor calculations (thus allowing for experimentation with modifications of the underlying electron density model), and provides tools for basic structural crystallographic operations. Permissively (MIT) licensed, DiSCaMB is an open-source C++ library that can be embedded in both academic and commercial tools for X-ray structure refinement.

  13. Active optics and the axisymmetric case: MINITRUST wide-field three-reflection telescopes with mirrors aspherized from tulip and vase forms

    Science.gov (United States)

    Lemaitre, Gerard R.; Montiel, Pierre; Joulie, Patrice; Dohlen, Kjetil; Lanzoni, Patrick

    2004-09-01

    Wide-field astronomy requires larger size telescopes. Compared to the catadioptric Schmidt, the optical properties of a three mirror telescope provides significant advantages. (1) The flat field design is anastigmatic at any wavelength, (2) the system is extremely compact -- four times shorter than a Schmidt -- and, (3) compared to a Schmidt with refractive corrector -- requiring the polishing of three optical surfaces --, the presently proposed Modified-Rumsey design uses all of eight available free parameters of a flat fielded anastigmatic three mirror telescope for mirrors generated by active optics methods. Compared to a Rumsey design, these parameters include the additional slope continuity condition at the primary-tertiary link for in-situ stressing and aspherization from a common sphere. Then, active optics allows the polishing of only two spherical surfaces: the combined primary-tertiary mirror and the secondary mirror. All mirrors are spheroids of the hyperboloid type. This compact system is of interest for space and ground-based astronomy and allows to built larger wide-field telescopes such as demonstrated by the design and construction of identical telescopes MINITRUST-1 and -2, f/5 - 2° FOV, consisting of an in-situ stressed double vase form primary-tertiary and of a stress polished tulip form secondary. Optical tests of these telescopes, showing diffraction limited images, are presented.

  14. Desempenho visual após implante de uma lente intraocular asférica multifocal difrativa Visual performance after implantation of an aspheric multifocal diffractive intraocular lens

    Directory of Open Access Journals (Sweden)

    Leonardo Akaishi

    2010-08-01

    Full Text Available OBJETIVO: Avaliar a acuidade visual a distancia, intermediária e perto após o implante de uma lente intraocular (LIO asférica multifocal difrativa AcrySof® ReSTOR® SN6AD1. MÉTODOS: Estudo prospectivo de 50 pacientes com catarata submetidos à facoemulsificação e implante de LIO AcrySof® ReSTOR®. Foram avaliados acuidade visual sem correção (AVSC, acuidade visual com correção (AVCC para longe, acuidade visual para perto corrigida para longe (AVPC e acuidade visual intermediária corrigida para longe (AVIC. Um questionário de satisfação e fenômenos visuais foi administrado ao final do estudo. RESULTADO: Após três meses de cirurgia, a média das acuidades (logMAR era: AVSC, 0,05 ± 0,07; AVCC, 0,00 ± 0,01; AVPC, 0,00 ± 0,0, e AVIC, 0,15 ± 0,05. A AVCC e AVPC era de 20/25 ou melhor em todos os pacientes, sendo a AVIC J3 ou melhor em 83% dos pacientes. Pacientes relataram excelente desempenho visual nas questões relacionadas a atividades para distância, intermediário, e perto com pouca ou nenhuma dificuldade. Nenhum paciente relatou halos ou 'glare' severos, sendo os mesmos caracterizados entre nenhum a moderado. CONCLUSÃO: A LIO asférica AcrySof® ReSTOR® SN6AD1 mostrou excelentes resultados na visão para longe, perto e intermediário, além de apresentar uma baixa incidência de fenômenos visuais.PURPOSE: To evaluate distance, intermediate, and near vision after aspheric multifocal diffractive AcrySof® ReSTOR® SN6AD1 intraocular lens (IOL implantation. METHODS: Prospective study of 50 patients with cataract that had phacoemulsification and AcrySof® ReSTOR® IOL implantation. Uncorrected distance vision acuity (UDVA, corrected distance visual acuity (CDVA, distance-corrected near visual acuity (DCNVA, and distance-corrected intermediate visual acuity (DCIVA were measured postoperatively. A patient-satisfaction and visual phenomena questionnaire was administered at the end of the study. RESULTS: Three months

  15. Comparison of clinical outcomes in PRK with a standard and aspherical optimized profile: a full case analysis of 100 eyes with 1-year follow-up.

    Science.gov (United States)

    Dausch, Dieter; Dausch, Burglinde; Wottke, Matthias; Sluyterman van Langeweyde, Georg

    2014-01-01

    One hundred eyes from 55 adult patients with myopia were retrospectively studied to determine the comparative safety, efficacy, and predictability of aberration smart ablation (ASA) and a new advanced ablation algorithm (Triple-A) using the MEL(®) 80 excimer laser. Fifty myopic eyes with a manifest refraction spherical equivalent (MRSE) between -1.0 diopters (D) and -9.75 D were consecutively treated with photorefractive keratec-tomy ASA, and 50 myopic eyes with an MRSE between -1.38 D and -11.0 D with photorefractive keratectomy Triple-A. Uncorrected distance visual acuity, MRSE, the absolute value of the cylinder, corrected distance visual acuity, and postoperative complications at 1 month, 3 months, 6 months, and 12 months (1 year) were descriptively analyzed and compared at 1 year. After 12 months, the MRSE variance was statistically significantly better in patients triaged to receive Triple-A compared with patients receiving ASA (ASA, ±0.7 D; Triple-A, ±0.15 D; P<0.001). Furthermore, no patient in the Triple-A group had any cylinder postoperatively. Patients in the Triple-A treatment arm achieved a superior result. No statistically significant difference in the two treatment arms was noted for the analysis of the mean MRSE at 12 months (P=0.78). Triple-A was more effective than standard aspherical surgical intervention in a number of treatment outcome parameters (eg, MRSE, astigmatism, efficacy index). The two surgical procedures were equivalent in terms of safety.

  16. Comparison of clinical outcomes in PRK with a standard and aspherical optimized profile: a full case analysis of 100 eyes with 1-year follow-up

    Directory of Open Access Journals (Sweden)

    Dausch D

    2014-11-01

    Full Text Available Dieter Dausch,1,2 Burglinde Dausch,2 Matthias Wottke,3 Georg Sluyterman van Langeweyde31Chung-Ang University, Seoul, South Korea; 2Augen-Laser-Klinik Nürnberg, Nuremberg, Germany; 3Carl Zeiss Meditec AG, Jena, Germany Purpose: One hundred eyes from 55 adult patients with myopia were retrospectively studied to determine the comparative safety, efficacy, and predictability of aberration smart ablation (ASA and a new advanced ablation algorithm (Triple-A using the MEL® 80 excimer laser.Methods: Fifty myopic eyes with a manifest refraction spherical equivalent (MRSE between -1.0 diopters (D and -9.75 D were consecutively treated with photorefractive keratectomy ASA, and 50 myopic eyes with an MRSE between -1.38 D and -11.0 D with photorefractive keratectomy Triple-A. Uncorrected distance visual acuity, MRSE, the absolute value of the cylinder, corrected distance visual acuity, and postoperative complications at 1 month, 3 months, 6 months, and 12 months (1 year were descriptively analyzed and compared at 1 year.Results: After 12 months, the MRSE variance was statistically significantly better in patients triaged to receive Triple-A compared with patients receiving ASA (ASA, ±0.7 D; Triple-A, ±0.15 D; P<0.001. Furthermore, no patient in the Triple-A group had any cylinder postoperatively. Patients in the Triple-A treatment arm achieved a superior result. No statistically significant difference in the two treatment arms was noted for the analysis of the mean MRSE at 12 months (P=0.78.Conclusion: Triple-A was more effective than standard aspherical surgical intervention in a number of treatment outcome parameters (eg, MRSE, astigmatism, efficacy index. The two surgical procedures were equivalent in terms of safety. Keywords: aberration smart ablation (ASA, manifest refraction spherical equivalent, Triple-A advanced ablation algorithm, uncorrected distance visual acuity, corrected distance visual acuity, excimer laser, PRK, ablation profile

  17. EXPLOSIVE NUCLEOSYNTHESIS IN THE NEUTRINO-DRIVEN ASPHERICAL SUPERNOVA EXPLOSION OF A NON-ROTATING 15 Msun STAR WITH SOLAR METALLICITY

    International Nuclear Information System (INIS)

    Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2011-01-01

    We investigate explosive nucleosynthesis in a non-rotating 15 M sun star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with a mass number ≤70, employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically symmetric progenitor, due to the growth of a low-mode SASI. The abundance pattern of the SN ejecta is similar to that of the solar system for models whose masses range between (0.4-0.5) M sun of the ejecta from the inner region (≤10, 000 km) of the precollapse core. For the models, the explosion energies and the 56 Ni masses are ≅ 10 51 erg and (0.05-0.06) M sun , respectively; their estimated baryonic masses of the neutron star are comparable to the ones observed in neutron-star binaries. These findings may have little uncertainty because most of the ejecta is composed of matter that is heated via the shock wave and has relatively definite abundances. The abundance ratios for Ne, Mg, Si, and Fe observed in the Cygnus loop are reproduced well with the SN ejecta from an inner region of the 15 M sun progenitor.

  18. Increased evidence for the prognostic value of primary tumor asphericity in pretherapeutic FDG PET for risk stratification in patients with head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hofheinz, Frank; Lougovski, Alexandr [Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, PET Center, Dresden (Germany); Zoephel, Klaus; Hentschel, Maria [University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Nuclear Medicine, Dresden (Germany); Steffen, Ingo G.; Wedel, Florian; Buchert, Ralph; Brenner, Winfried [Charite - Universitaetsmedizin Berlin, Department of Nuclear Medicine, Berlin (Germany); Apostolova, Ivayla [Universitaetsklinikum Magdeburg A.oe.R., Klinik fuer Radiologie und Nuklearmedizin, Magdeburg (Germany); Baumann, Michael [University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Radiation Oncology, Dresden (Germany); OncoRay - National Center for Radiation Research in Oncology, Dresden (Germany); Institute of Radiooncology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Kotzerke, Joerg; Hoff, Joerg van den [Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, PET Center, Dresden (Germany); University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Nuclear Medicine, Dresden (Germany)

    2014-11-22

    In a previous study, we demonstrated the first evidence that the asphericity (ASP) of pretherapeutic FDG uptake in the primary tumor provides independent prognostic information in patients with head and neck cancer. The aim of this work was to confirm these results in an independent patient group examined at a different site. FDG-PET/CT was performed in 37 patients. The primary tumor was delineated by an automatic algorithm based on adaptive thresholding. For the resulting ROIs, the metabolically active part of the tumor (MTV), SUV{sub max}, SUV{sub mean}, total lesion glycolysis (TLG) and ASP were computed. Univariate Cox regression with respect to progression free survival (PFS) and overall survival (OS) was performed. For survival analysis, patients were divided in groups of high and low risk according to the parameter cut-offs defined in our previous work. In a second step, the cut-offs were adjusted to the present data. Univariate and multivariate Cox regression was performed for the pooled data consisting of the current and the previously described patient group (N = 68). In multivariate Cox regression, clinically relevant parameters were included. Univariate Cox regression using the previously published cut-off values revealed TLG (hazard ratio (HR) = 3) and ASP (HR = 3) as significant predictors for PFS. For OS MTV (HR = 2.7) and ASP (HR = 5.9) were significant predictors. Using the adjusted cutoffs MTV (HR = 2.9/3.3), TLG (HR = 3.1/3.3) and ASP (HR = 3.1/5.9) were prognostic for PFS/OS. In the pooled data, multivariate Cox regression revealed a significant prognostic value with respect to PFS/OS for MTV (HR = 2.3/2.1), SUV{sub max} (HR = 2.1/2.5), TLG (HR = 3.5/3.6), and ASP (HR = 3.4/4.4). Our results confirm the independent prognostic value of ASP of the pretherapeutic FDG uptake in the primary tumor in patients with head and neck cancer. Moreover, these results demonstrate that ASP can be determined unambiguously across different sites. (orig.)

  19. Effect of aspherical and yellow tinted intraocular lens on blue-on-yellow perimetry Efeito das lentes intraoculares asféricas e com pigmentação amarela na campimetria azul-amarelo

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2012-10-01

    Full Text Available PURPOSE: To investigate the possible effect of aspherical or yellow tinted intraocular lens (IOL on contrast sensitivity and blue-on-yellow perimetry. METHODS: This prospective randomized bilateral double-masked clinical study included 52 patients with visually significant bilateral cataracts divided in two groups; 25 patients (50 eyes received aspherical intraocular lens in one eye and spherical intraocular lens in the fellow eye; and 27 patients (54 eyes received ultraviolet and blue light filter (yellow tinted IOL implantation in one eye and acrylic ultraviolet filter IOL in the fellow eye. The primary outcome measures were contrast sensitivity and blue-on-yellow perimetry values (mean deviation [MD] and pattern standard deviation [PSD] investigated two years after surgery. The results were compared intra-individually. RESULTS: There was a statistically significant between-group (aspherical and spherical intraocular lens difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. There were no between-group significant differences (yellow tinted and clear intraocular lens under photopic or mesopic conditions. There was no statistically significant difference between all intraocular lens in MD or PSD. CONCLUSION: Contrast sensitivity was better under mesopic conditions with aspherical intraocular lens. Blue-on-yellow perimetry did not appear to be affected by aspherical or yellow tinted intraocular lens. Further studies with a larger sample should be carried out to confirm or not that hypotheses.OBJETIVO: Investigar a possibilidade de efeitos na sensibilidade ao contraste e nos resultados da campimetria azul-amarelo com implante de uma lente intraocular (LIO asférica ou de pigmentação amarela. MÉTODOS: Trata-se de um estudo prospectivo, randomizado, duplo-mascarado, envolvendo 52 pacientes portadores de catarata senil bilateral, divididos em dois grupos; 25

  20. Fiscal 2000 achievement report on the venture business assisting type regional consortium - Core industry creation type. Research and development of high-accuracy fabrication technology of aspheric optical component creation technology using parallel grinding method; 2000 nendo chiiki consortium kenkyu kaihatsu jigyo seika hokokusho. Parallel kensaku hoshiki ni yoru koseido hikyumen kogaku soshi sosei gijutsu no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    Research and development was carried out for the establishment and commercialization of the technical seeds of a newly proposed 'parallel grinding type aspheric surface grinding method,' based on the results of studies of ultra-accuracy grinding and aspheric surface machining technologies conducted at Tohoku University. The new method is characterized in that a work point on the work piece faces the grinding point on the grindstone cross section on the one-to-one basis because the grinding point travels on the grindstone cross section. Accordingly, the method is quite suitable for corrective grinding for eliminating only the error in case a geometrical error occurs on the wrought surface. For this purpose, measurement of the machine surface on board the machine is indispensable. Hence: a study of corrective grinding methods under an on-board measuring system. As the result, the initially intended geometrical accuracy level was attained in the machining of axis-symmetric aspheric glass lenses and aspheric metal molds, and coarseness on the finished surface in the grinding of glass lenses was reduced to 0.3{mu}m using a diamond grindstone. In conclusion, machining accuracy and finished surface coarseness were remarkably improved, and this enables machining without the need of polishing and demonstrates that there are possibilities of commercialization. (NEDO)

  1. Comparación del LASIK convencional y el LASIK asférico en el tratamiento de la ametropía Comparison of conventional LASIK and aspheric LASIK in the treatment of ametropia

    Directory of Open Access Journals (Sweden)

    Yanaisa Riverón Ruiz

    2012-12-01

    Full Text Available Objetivo: comparar los resultados del LASIK con patrón de ablación convencional y el asférico en la corrección de ametropías y evaluar la sensibilidad al contraste en ambos procedimientos. Métodos: se realizó un estudio comparativo y prospectivo en 64 pacientes de la consulta externa del Servicio de Cirugía Refractiva del Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Estos fueron distribuidos aleatoriamente en dos grupos iguales para ambas técnicas. Las variables estudiadas fueron agudeza visual sin corrección y mejor corregida, aberración y sensibilidad al contraste en condiciones fotópicas. Resultados: la agudeza visual sin corrección mejoró ocho líneas en la cartilla de Snellen, sin diferencias entre ambos procedimientos. La aberración esférica presentó un valor medio inferior en el tratamiento asférico (0,30. Se encontró una disminución de la sensibilidad al contraste después del tratamiento convencional. Conclusiones: ambas técnicas quirúrgicas mantienen una buena agudeza visual con corrección y sin esta, después de la cirugía en ambientes fotópicos. La calidad visual del tratamiento asférico es superior, al inducir menor aberración esférica y mejor sensibilidad al contraste después de cirugía.Objective: to compare the results obtained with the LASIK using both conventional and aspheric patterns to correct ametropies and to evaluate the contrast sensitivity after these two procedures. Methods: a comparative and prospective study was conducted in 64 patients who attended the refractive surgery outpatient service of “Ramon Pando Ferrer” Cuban Institute of Ophthalmology. They were randomly distributed in two groups for both procedures. Several variables were studied such as: uncorrected visual acuity, best corrected visual acuity, aberration and contrast sensitivity at photopic conditions. Results: uncorrected visual acuity improved 8 lines in the Snellen’s chart, without significant

  2. Development of an aspheric 22-diopter 50-mm diameter magnifier Desenvolvimento de uma lupa asférica de 22 dioptrias de 50 mm de diâmetro

    Directory of Open Access Journals (Sweden)

    José Américo Bonatti

    2008-04-01

    Full Text Available PURPOSE: To develop in an interdisciplinary approach between ophthalmology and design areas an ergonomic +22-diopter 50-mm aspheric hand magnifier for low vision. METHODS: An aluminum cylinder was cut, processed using a lathe and carved to produce a ring that accommodated a 50-mm aspheric lens, with an external depression not to slide from the holder's fingers. A cylindrical steel bar was cut, processed using a lathe and carved in order to form an externally turned ring to be screwed into the internal thread of the aluminum ring, to maintain the lens in a steady position. Both rings were submitted to electrostatic painting with a dull black electrostatic Epoxi ink, except the lower border of the external ring, to indicate the correct side of the magnifier to face the material to be read. RESULTS: A 22-diopter 50-mm diameter aspheric lens magnifier with a black ring to be hold at its external circular depression was obtained in order to safely search the adequate reading focus with an inferior aluminum colored ring to face the object to be read and allow a less distorted reading. This is the first Brazilian high-magnification great-diameter magnifier for low vision that permits basically the focusing on an entire word, not only syllables, in order to allow a faster and more comfortable reading. CONCLUSIONS: By an interdisciplinary approach a 22-diopter 50-mm aspheric lens magnifier was developed with image and ergonomic characteristics such as to permit comfortable and adequate reading performance in cases of low vision.OBJETIVO: Desenvolver de modo interdisciplinar entre as áreas de oftalmologia e design uma lupa de mão ergonômica de +22 dioptrias de 50 mm de diâmetro asférica para baixa visão. MÉTODOS: Um cilindro de alumínio foi cortado, torneado e teve feita internamente uma rosca a fim de produzir um anel para acomodar uma lente asférica de 50 mm de diâmetro com uma depressão externa para não escorregar dos dedos do portador. Uma

  3. Functional and refractive results after one month of AcrySof toric intraocular lens implantation

    Directory of Open Access Journals (Sweden)

    Francisco Alba-Bueno

    2011-04-01

    Conclusions: The implantation of SN60T toric IOL in patients with CA higher than 0.75 D is a safe, predictable and effective way of reducing refractive astigmatism in patients undergoing cataract surgery.

  4. Manipulating quantum states with aspheric lenses

    International Nuclear Information System (INIS)

    Wang Zhiwei; Ren Xifeng; Huang Yunfeng; Zhang Yongsheng; Guo Guangcan

    2005-01-01

    We present an experimental demonstration to manipulate the width and position of the down-converted beam waist. Our results can be used to engineer the two-photon orbital angular momentum (OAM) entangled states (such as concentrating OAM entangled states) and generate Hermite-Gaussian (HG) modes entangled states

  5. Aspherical Supernovae: Effects on Early Light Curves

    Science.gov (United States)

    Afsariardchi, Niloufar; Matzner, Christopher D.

    2018-04-01

    Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of nonradial flows at the time of shock breakout. These develop in sufficiently nonspherical explosions if the progenitor is not too diffuse. When they do develop, nonradial flows limit ejecta speeds and cause ejecta–ejecta collisions. We explore these phenomena and their observational implications using global, axisymmetric, nonrelativistic FLASH simulations of simplified polytropic progenitors, which we scale to representative stars. We develop a method to track photon production within the ejecta, enabling us to estimate band-dependent light curves from adiabatic simulations. Immediate breakout emission becomes hidden as an oblique flow develops. Nonspherical effects lead the shock-heated ejecta to release a more constant luminosity at a higher, evolving color temperature at early times, effectively mixing breakout light with the early light curve. Collisions between nonradial ejecta thermalize a small fraction of the explosion energy; we will address emission from these collisions in a subsequent paper.

  6. Absolute Heterodyne Interferometer for Strongly Aspherical Mirrors

    NARCIS (Netherlands)

    Krieg, M.L.

    2004-01-01

    For the past thirty years, microchips have doubled in complexity every two years. This increasing complexity required that the size of the structures written on silicon halve at the same rate. A fundamentally limiting factor to the size of microchip structures is the wavelength of the lithographic

  7. A pilot study to determine if intraocular lens choice at the time of cataract surgery has an impact on patient-reported driving habits

    Directory of Open Access Journals (Sweden)

    Beiko GHH

    2015-08-01

    Full Text Available George HH Beiko1,2 1Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada; 2Division of Ophthalmology, Department of Surgery, McMaster University, Hamilton, ON, CanadaPurpose: To determine if intraocular lens (IOL choice at the time of cataract surgery affects driving habits.Materials and methods: Pseudophakes who were 28–35 months postbilateral cataract surgery with one of two contemporary one-piece hydrophobic acrylic IOLs (SN60WF or ZCB00 were asked to complete the Driving Habits Questionnaire, a validated instrument for determining self-reported driving status, frequency, and difficulty. To determine if there were any differences in driving habits between the two groups, t-tests and χ2 tests were used.Results: Of 90 respondents, 72 (40 SN60WF and 32 ZCB00 were still active drivers. The SN60WF-implanted subjects were less likely to drive at the same speed or faster than the general flow of traffic, less likely to rate their quality of driving as average/above average, less likely to have traveled beyond their immediate neighborhood, less likely to drive at night, more likely to have moderate-to-severe difficulty driving at night, and more likely to have self-reported road traffic accidents. The differences did not reach statistical significance.Conclusion: Changes in patients’ driving habits 2–3 years after cataract surgery may be associated with the type of IOL implanted. A larger study, powered to demonstrate statistical significance, is needed to verify the trends identified in this pilot study and discover possible contributing factors.Keywords: intraocular lens, cataract surgery, driving habits, disability glare, retinal straylight, accidents

  8. Optical Metrology of Aspheric and Freeform Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Science Missions Directorate seeks technology for cost-effective high-performance advanced space telescopes for astrophysics and Earth science applications....

  9. Aspheric lens based imaging receiver for MIMO visible light communication

    Science.gov (United States)

    Ju, Qiuqi; Liang, Zhongcheng; Liu, Xueming; Yang, Tingting; Wang, Jin

    2014-10-01

    Visible light communication (VLC) has been regarded as a promising solution in short-range intelligent communication system. Nowadays, the research is focused on integrating the multi-input multi-output (MIMO) technique in the VLC system, to achieve a larger transmission capacity and stronger transmission reliability. However, one important issue should be addressed due to the use of MIMO technology: the multipath inter-symbol interference. The multipath intersymbol interference comes from the reflection of the signal in the room and channel crosstalk between different channels. In this paper, we propose a novel optical system used in the MIMO VLC system to reduce multipath interference dramatically. Signals from different LEDs can be separated by using parabolic lens plated with reflecting film. This structure can reduce the reflection effect effectively as well. We present the simulation results to observe the distribution of optical power on the imaging plane for various receiving positions and low correlation between all channels. We can find that the optical power density becomes stronger than non-imaging system and the interference is sharply decreased, thus the SNR and BER are also optimized. Analysis about the optical system is given in this paper.

  10. Design and fabrication of aspherical bimorph PZT optics

    CERN Document Server

    Tseng, T C; Yeh, Z C; Perng, S Y; Wang, D J; Kuan, C K; Chen, J R; Chen, C T

    2001-01-01

    Bimorph piezoelectric optics with a third-order-polynomial surface is designed and a prototype is fabricated as active optics. Two pairs of silicon (Si) and lead zirconate titanate (PZT) piezoelectric ceramic are bonded as Si-PZT-PZT-Si together with a multi-electrode or thin film resistor coating used as the control electrode between Si and PZT and metallic films as grounding between the interface of PZT ceramics. A linear voltage is applied to the bimorph PZT optics by probing the control electrodes from a two-channel controllable power supplier. In doing so, the optics surface can achieve a desired third-order-polynomial surface. Reducing hysteresis and creep in bimorph PZT X-ray optics is the only feasible way by inserting an appropriate capacitor in series with bimorph PZT optics to significantly reduce both effects.

  11. APS 3D: a new benchmark in aspherical polishing

    Science.gov (United States)

    Gauch, Daniel; Mikulic, Dalibor; Veit, Christian

    2017-10-01

    The APS 3D system performs polishing and form correction in one step in order to reduce overall process time, reduce the number of polishing steps required and eliminate the need for highly skilled operators while providing a repeatable polishing process. This new 3D Polishing system yields better surface quality, and a better slope error, automatically determining the optimum speeds, feed rates and polish pressures to achieve a deterministic process based on the required quality parameters input by the operator. The process flow is always the same to ensure consistent quality and target quality values are defined before polishing begins.

  12. Comparative study on optical performance and visual outcomes between two diffractive multifocal lenses: AMO Tecnis ® ZMB00 and AcrySof ® IQ ReSTOR ® Multifocal IOL SN6AD1

    Directory of Open Access Journals (Sweden)

    Mario Augusto Pereira Dias Chaves

    2016-06-01

    Full Text Available ABSTRACT Purpose: To compare the optical performance and visual outcomes between two diffractive multifocal lenses: AMO Tecnis® ZMB00 and AcrySof® ReSTOR® SN6AD1. Methods: This prospective, non-randomized comparative study included the assessment of 74 eyes in 37 patients referred for cataract surgery and candidates for multifocal intraocular lens implants. Exclusion criteria included existence of any other eye disease, previous eye surgery, high axial myopia, preoperative corneal astigmatism of >1.00 cylindrical diopter (D, and intraoperative or postoperative complications. Ophthalmological evaluation included the measurement of uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA, distance-corrected near visual acuity (DCNVA, and distance-corrected intermediate visual acuity (DCIVA, with analysis of contrast sensitivity (CS, wavefront, and visual defocus curve. Results: Postoperative UDVA was 0.09 and 0.08 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.868; postoperative CDVA was 0.04 and 0.02 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.68; DCIVA was 0.17 and 0.54 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.000; and DCNVA was 0.04 and 0.09 logMAR in the SN6AD1 and ZMB00 groups, respectively (p=0.001. In both cases, there was an improvement in the spherical equivalent and UDVA (p<0.05. Under photopic conditions, the SN6AD1 group had better CS at low frequencies without glare (p=0.04; however, the ZMB00 group achieved better sensitivity at high frequencies with glare (p=0.003. The SN6AD1 and ZMB00 lenses exhibited similar behavior for intermediate vision, according to the defocus curve; however, the ZMB00 group showed a shorter reading distance than the SN6AD1 group. There were no significant differences regarding aberrometry between the two groups. Conclusion: Both lenses promoted better quality of vision for both long and short distances and exhibited a similar behavior for intermediate vision. The SN6AD1 and ZMB00 groups showed better results for CS under photopic conditions at low and high spatial frequencies, respectively.

  13. Elaboração e validação do questionário de satisfação dos pacientes pseudofácicos em português

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2013-12-01

    Full Text Available OBJETIVO: Elaborar e validar o questionário de qualidade de vida na versão do idioma português. MÉTODOS: O questionário "Cataract TyPESpecification" modificado foi desenvolvido especificamente para avaliar a qualidade de vida pós-cirurgia de catarata. O questionário avaliou 10 itens status funcionais por meio de 18 perguntas. Foi aplicado por um único examinador, com o objetivo de graduar a satisfação visual de 0 a 10 (0 muito insatisfeito; 5 neutro; 10 muito satisfeito. Houve estudo prospectivo comparativo, não randomizado, que incluiu 142 olhos de 71 pacientes com catarata da Universidade de São Paulo. A avaliação oftalmológica contou com medida da acuidade visual para longa, intermediária e curta distâncias, sem correção e com a melhor correção óptica e questionário de satisfação. Foi submetido a um questionário de satisfação quanto à acuidade visual e fenômenos fóticos. Todos os exames foram realizados com 6 meses de pós-operatório. RESULTADOS: A média de idade dos pacientes foi de 60,7 ± 6,6 anos no grupo Tecnis, 63,1 ± 4,4 anos no grupo Restor e 63,7 ± 4,2 anos no grupo SN60AT/SN60WF. A acuidade visual para perto não-corrigida e a corrigida para longe foram estatisticamente superiores nos grupos Restor® e Tecnis® comparadas ao grupo SN60AT/SN60WF (p<0,001. Não houve diferença estatística entre os grupos quando comparadas a acuidade visual para longe não-corrigida e a melhor corrigida (p=0,56. O questionário de satisfação apresentou maior independência de óculos a favor da Tecnis® (9,3/10 e Restor® (8,7/10, mas com mais queixas de halos (Restor® 18,8%; Tecnis® 21,7% e glare (Restor® 25%; Tecnis® 26,1% do que no grupo SN60AT/SN60WF. CONCLUSÃO: A Restor® e Tecnis® apresentaram melhor acuidade visual para perto do que o grupo SN60AT/SN60WF. As lentes Restor® e Tecnis® apresentaram maior satisfação na visão de perto e independência do uso de óculos e fenômenos fóticos do que as

  14. Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

    KAUST Repository

    Kim, Sanghoon; Ueda, Kohei; Go, Gyungchoon; Jang, Peong-Hwa; Lee, Kyung-Jin; Belabbes, Abderrezak; Manchon, Aurelien; Suzuki, Motohiro; Kotani, Yoshinori; Nakamura, Tetsuya; Nakamura, Kohji; Koyama, Tomohiro; Chiba, Daichi; Yamada, Kihiro. T.; Kim, Duck-Ho; Moriyama, Takahiro; Kim, Kab-Jin; Ono, Teruo

    2018-01-01

    Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii

  15. Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

    KAUST Repository

    Kim, Sanghoon

    2018-04-19

    Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii–Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required. Here we experimentally demonstrate the close correlation of the DMI with the anisotropy of the orbital magnetic moment and with the magnetic dipole moment of the ferromagnetic metal in addition to Heisenberg exchange. The density functional theory and the tight-binding model calculations reveal that inversion symmetry breaking with spin–orbit coupling gives rise to the orbital-related correlation. Our study provides the experimental connection between the orbital physics and the spin–orbit-related phenomena, such as DMI.

  16. Phase Inversion: Inferring Solar Subphotospheric Flow and Other Asphericity from the Distortion of Acoustic Waves

    Science.gov (United States)

    Gough, Douglas; Merryfield, William J.; Toomre, Juri

    1998-01-01

    A method is proposed for analyzing an almost monochromatic train of waves propagating in a single direction in an inhomogeneous medium that is not otherwise changing in time. An effective phase is defined in terms of the Hilbert transform of the wave function, which is related, via the JWKB approximation, to the spatial variation of the background state against which the wave is propagating. The contaminating effect of interference between the truly monochromatic components of the train is eliminated using its propagation properties. Measurement errors, provided they are uncorrelated, are manifest as rapidly varying noise; although that noise can dominate the raw phase-processed signal, it can largely be removed by low-pass filtering. The intended purpose of the analysis is to determine the distortion of solar oscillations induced by horizontal structural variation and material flow. It should be possible to apply the method directly to sectoral modes. The horizontal phase distortion provides a measure of longitudinally averaged properties of the Sun in the vicinity of the equator, averaged also in radius down to the depth to which the modes penetrate. By combining such averages from different modes, the two-dimensional variation can be inferred by standard inversion techniques. After taking due account of horizontal refraction, it should be possible to apply the technique also to locally sectoral modes that propagate obliquely to the equator and thereby build a network of lateral averages at each radius, from which the full three-dimensional structure of the Sun can, in principle, be determined as an inverse Radon transform.

  17. Novel CNC Grinding Process Control for Nanometric Surface Roughness for Aspheric Space Optical Surfaces

    Directory of Open Access Journals (Sweden)

    Jeong-Yeol Han

    2004-06-01

    Full Text Available Optics fabrication process for precision space optical parts includes bound abrasive grinding, loose abrasive lapping and polishing. The traditional bound abrasive grinding with bronze bond cupped diamond wheel leaves the machine marks of about 20 μm rms in height and the subsurface damage of about 1 μm rms in height to be removed by subsequent loose abrasive lapping. We explored an efficient quantitative control of precision CNC grinding. The machining parameters such as grain size, work-piece rotation speed and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis. The effectiveness of such grinding prediction models was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment achieved the predictability down to ±20 nm in height and the surface roughness down to 36 nm in height. This study contributed to improvement of the process efficiency reaching directly the polishing and figuring process without the need for the loose abrasive lapping stage.

  18. Additive Manufactured Very Light Weight Diamond Turned Aspheric Mirror, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Selective laser melting, referred to as "Direct Metal Laser Sintering"(DMLS), "Metal Powder Bed Fusion" or "3D Printing" is an additive manufacturing process which...

  19. Cryo-optical testing of large aspheric reflectors operating in the sub mm range

    Science.gov (United States)

    Roose, S.; Houbrechts, Y.; Mazzoli, A.; Ninane, N.; Stockman, Y.; Daddato, R.; Kirschner, V.; Venacio, L.; de Chambure, D.

    2006-02-01

    The cryo-optical testing of the PLANCK primary reflector (elliptical off-axis CFRP reflector of 1550 mm x 1890 mm) is one of the major issue in the payload development program. It is requested to measure the changes of the Surface Figure Error (SFE) with respect to the best ellipsoid, between 293 K and 50 K, with a 1 μm RMS accuracy. To achieve this, Infra Red interferometry has been used and a dedicated thermo mechanical set-up has been constructed. This paper summarises the test activities, the test methods and results on the PLANCK Primary Reflector - Flight Model (PRFM) achieved in FOCAL 6.5 at Centre Spatial de Liege (CSL). Here, the Wave Front Error (WFE) will be considered, the SFE can be derived from the WFE measurement. After a brief introduction, the first part deals with the general test description. The thermo-elastic deformations will be addressed: the surface deformation in the medium frequency range (spatial wavelength down to 60 mm) and core-cell dimpling.

  20. A comparison of visual outcomes in three different types of monofocal intraocular lenses.

    Science.gov (United States)

    Shetty, Vijay; Haldipurkar, Suhas S; Gore, Rujuta; Dhamankar, Rita; Paik, Anirban; Setia, Maninder Singh

    2015-01-01

    To compare the visual outcomes (distance and near) in patients opting for three different types of monofocal intraocular lens (IOL) (Matrix Aurium, AcrySof single piece, and AcrySof IQ lens). The present study is a cross-sectional analysis of secondary clinical data collected from 153 eyes (52 eyes in Matrix Aurium, 48 in AcrySof single piece, and 53 in AcrySof IQ group) undergoing cataract surgery (2011-2012). We compared near vision, distance vision, distance corrected near vision in these three types of lenses on day 15 (±3) post-surgery. About 69% of the eyes in the Matrix Aurium group had good uncorrected distance vision post-surgery; the proportion was 48% and 57% in the AcrySof single piece and AcrySof IQ group (P=0.09). The proportion of eyes with good distance corrected near vision were 38%, 33%, and 15% in the Matrix Aurium, AcrySof single piece, and AcrySof IQ groups respectively (P=0.02). Similarly, The proportion with good "both near and distance vision" were 38%, 33%, and 15% in the Matrix Aurium, AcrySof single piece, and AcrySof IQ groups respectively (P=0.02). It was only the Matrix Aurium group which had significantly better both "distance and near vision" compared with the AcrySof IQ group (odds ratio: 5.87, 95% confidence intervals: 1.68 to 20.56). Matrix Aurium monofocal lenses may be a good option for those patients who desire to have a good near as well as distance vision post-surgery.

  1. Design and high-volume manufacture of low-cost molded IR aspheres for personal thermal imaging devices

    Science.gov (United States)

    Zelazny, A. L.; Walsh, K. F.; Deegan, J. P.; Bundschuh, B.; Patton, E. K.

    2015-05-01

    The demand for infrared optical elements, particularly those made of chalcogenide materials, is rapidly increasing as thermal imaging becomes affordable to the consumer. The use of these materials in conjunction with established lens manufacturing techniques presents unique challenges relative to the cost sensitive nature of this new market. We explore the process from design to manufacture, and discuss the technical challenges involved. Additionally, facets of the development process including manufacturing logistics, packaging, supply chain management, and qualification are discussed.

  2. Differences of Longitudinal Chromatic Aberration (LCA) between Eyes with Intraocular Lenses from Different Manufacturers

    Science.gov (United States)

    Nakajima, Masashi; Hiraoka, Takahiro; Yamamoto, Toshiya; Takagi, Seiu; Hirohara, Yoko; Oshika, Tetsuro

    2016-01-01

    Several researchers have studied the longitudinal chromatic aberration (LCA) of eyes implanted with an intraocular lens (IOL). We investigated the LCA of eyes implanted with yellow-colored IOLs from three different manufacturers: Alcon Inc., HOYA Corp., and AMO Inc. The number of subjects was 11, 16, and 16, respectively. The LCA of eyes implanted with SN60WF and SN60AT (Alcon Inc.), and with XY-1 (HOYA Corp.), was the same as that of phakic eyes. The LCA of eyes with ZCB00V (AMO Inc.) was smaller than that of phakic eyes. The LCA of eyes implanted with Alcon’s and HOYA’s IOLs, but not the LCA of eyes implanted with AMO’s IOLs, was positively correlated with the powers of the IOLs. We also performed simulations to verify the impacts of LCA on visual performance for 4-mm pupil diameter; the simulations were a polychromatic modulation transfer function (MTF) and a visual Strehl ratio computed on the basis of an optical transfer function (VSOTF). We concluded that the differences between the LCA of different manufacturers do not affect visual performances when some extent of higher-order aberration (HOA) exists. The smaller HOA of AMO IOLs may enhance visual performance. PMID:27258141

  3. The nebular spectra of the transitional Type Ia Supernovae 2007on and 2011iv: broad, multiple components indicate aspherical explosion cores

    Science.gov (United States)

    Mazzali, P. A.; Ashall, C.; Pian, E.; Stritzinger, M. D.; Gall, C.; Phillips, M. M.; Höflich, P.; Hsiao, E.

    2018-05-01

    The nebular-epoch spectrum of the rapidly declining, `transitional' Type Ia supernova (SN) 2007on showed double emission peaks, which have been interpreted as indicating that the SN was the result of the direct collision of two white dwarfs. The spectrum can be reproduced using two distinct emission components, one redshifted and one blueshifted. These components are similar in mass but have slightly different degrees of ionization. They recede from one another at a line-of-sight speed larger than the sum of the combined expansion velocities of their emitting cores, thereby acting as two independent nebulae. While this configuration appears to be consistent with the scenario of two white dwarfs colliding, it may also indicate an off-centre delayed detonation explosion of a near-Chandrasekhar-mass white dwarf. In either case, broad emission line widths and a rapidly evolving light curve can be expected for the bolometric luminosity of the SN. This is the case for both SNe 2007on and 2011iv, also a transitional SN Ia that exploded in the same elliptical galaxy, NGC 1404. Although SN 2011iv does not show double-peaked emission line profiles, the width of its emission lines is such that a two-component model yields somewhat better results than a single-component model. Most of the mass ejected is in one component, however, which suggests that SN 2011iv was the result of the off-centre ignition of a Chandrasekhar-mass white dwarf.

  4. 3-Month experience in presbyopic correction with bi-aspheric multifocal central presbyLASIK treatments for hyperopia and myopia with or without astigmatism

    Directory of Open Access Journals (Sweden)

    Michiel H.A. Luger

    2012-01-01

    Conclusions: Patient selection and expectation management are essential to achieve patient satisfaction. Even though optically the results are quite predictable, some patients find it difficult to adapt to the compromise between far and near vision, and others are dissatisfied by the minor loss of distance VA.

  5. Photoprotection and photoreception of intraocular lenses under xenon and white LED illumination.

    Science.gov (United States)

    Artigas, J M; Navea, A; García-Domene, M C; Artigas, C; Lanzagorta, A

    2016-05-01

    To analyze the photoprotection and phototransmission that various intraocular lenses (IOLs) provide under the illumination of a xenon (Xe) lamp and white LEDs (light emitting diode). The spectral transmission curves of six representative IOLs were measured using a Perkin-Elmer Lambda 35 UV/VIS spectrometer. Various filtering simulations were performed using a Xe lamp and white LEDs. The spectral emissions of these lamps were measured with an ILT-950 spectroradiometer. The IOLs analyzed primarily show transmission of nearly 100% in the visible spectrum. In the ultraviolet (UV) region, the filters incorporated in the various IOLs did not filter equally, and some of them let an appreciable amount of UV through. The Xe lamp presented a strong emission of ultraviolet A (UVA), and its emission under 300nm was not negligible. The white LED did not present an appreciable emission under 380nm. The cut-off wavelength of most filters is between 380 and 400nm (Physiol Hydriol60C(®), IOLTECH E4T(®), Alcon SA60AT(®), Alcon IQ SN60WF(®)), so that their UV protection is very effective. Nonetheless, the IOL OPHTEC Oculaid(®) contains a filter that, when a Xe lamp is used, lets through up to 20% for 350nm and up to 15% for 300nm, which at this point is ultraviolet B (UVB). The OPHTEC(®) Artisan IOL has a transmission peak below 300nm, which must be taken into account under Xe illumination. White LEDs do not emit energy below 380nm, so no special protection is required in the UV region. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Management of sulcus-fixated single-piece intraocular lens-induced pigmentary glaucoma with 3-piece IOL exchange.

    Science.gov (United States)

    Rabie, Hossein Mohammad; Esfandiari, Hamed; Rikhtegar, Mohammad Hassan; Hekmat, Vahid

    2018-02-01

    To describe our experience with exchanging sulcus-fixated single-piece intraocular lens (IOL) with 3-piece IOLs for management of pigmentary glaucoma. In this retrospective study, records of patients who underwent sulcus-fixated single-piece IOL exchanged with 3-piece IOLs were retrieved, and demographic and baseline data of patients, type of IOL, pre- and post-IOL exchange BCVA, IOP, number of anti-glaucoma medications, and optic nerve head examination were documented. Baseline and final examinations were analyzed and compared. Mean age of the patients was 59 ± 10 years, and 5 (41.6%) were female. Mean interval between primary cataract extraction operation and IOL exchange was 17 ± 5 months. Nine patients received in sulcus implantation of Alcon SA60AT, and three patients had SN60WF model at the end of primary surgery. BCVA changed insignificantly from 0.06 ± 0.06 logMAR to 0.06 ± 0.06 after IOL exchange. (P = 0.22) IOP was controlled in 8 cases (66.6%), but four cases (33.3%) needed glaucoma surgery to further control glaucoma condition. IOP decreased significantly from preoperative 17 ± 3 to 14 ± 1 mmHg postoperatively. Patients with advanced age and higher baseline IOP were more likely to undergo glaucoma surgery after IOL exchange. (P = 0.07 and 0.00, respectively). single-piece IOL exchange with 3-piece IOL dramatically decreases pigment release and reduces IOP. Those with advanced age and higher IOP are less likely to respond to IOL exchange and may need glaucoma surgery to control high intraocular pressure.

  7. Visual performance after bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocal versus extended range of vision.

    Science.gov (United States)

    Monaco, Gaspare; Gari, Mariangela; Di Censo, Fabio; Poscia, Andrea; Ruggi, Giada; Scialdone, Antonio

    2017-06-01

    To compare the visual outcomes and quality of vision of 2 new diffractive multifocal intraocular lenses (IOLs) with those of a monofocal IOL. Fatebenefratelli e Oftalmico Hospital, Milan, Italy. Prospective case series. Patients had bilateral cataract surgery with implantation of a trifocal IOL (Panoptix), an extended-range-of-vision IOL (Symfony), or a monofocal IOL (SN60WF). Postoperative examinations included assessing distance, intermediate, and near visual acuity; binocular defocus; intraocular and total aberrations; point-spread function (PSF); modulation transfer function (MTF); retinal straylight; and quality-of-vision (QoV) and spectacle-dependence questionnaires. Seventy-six patients (152 eyes) were assessed for study eligibility. Twenty patients (40 eyes) in each arm of the study (60 patients, 120 eyes) completed the outcome assessment. At the 4-month follow-up, the trifocal group had significantly better near visual acuity than the extended-range-of-vision group (P = .005). The defocus curve showed the trifocal IOL had better intermediate/near performance than the extended-range-of-vision IOL and both multifocal IOLs performed better than the monofocal IOL. Intragroup comparison of the total higher-order aberrations, PSF, MTF, and retinal straylight were not statistically different. The QoV questionnaire results showed no differences in dysphotopsia between the multifocal IOL groups; however, the results were significantly higher than in the monofocal IOL group. Both multifocal IOLs seemed to be good options for patients with intermediate-vision requirements, whereas the trifocal IOL might be better for patients with near-vision requirements. The significant perception of visual side effects indicates that patients still must be counseled about these effects before a multifocal IOL is implanted. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  8. A study of optical design and optimization applied to lens module of laser beam shaping of advanced modern optical device

    Science.gov (United States)

    Tsai, Cheng-Mu; Fang, Yi-Chin; Chen, Zhen Hsiang

    2011-10-01

    This study used the aspheric lens to realize the laser flat-top optimization, and applied the genetic algorithm (GA) to find the optimal results. Using the characteristics of aspheric lens to obtain the optimized high quality Nd: YAG 355 waveband laser flat-top optical system, this study employed the Light tools LDS (least damped square) and the GA of artificial intelligence optimization method to determine the optimal aspheric coefficient and obtain the optimal solution. This study applied the aspheric lens with GA for the flattening of laser beams using two aspheric lenses in the aspheric surface optical system to complete 80% spot narrowing under standard deviation of 0.6142.

  9. A Sensitivity Study on the Effects of Particle Chemistry, Asphericity and Size on the Mass Extinction Efficiency of Mineral Dust in the Earth's Atmosphere: From the Near to Thermal IR

    Science.gov (United States)

    Hansell, R. A., Jr.; Reid, J. S.; Tsay, S. C.; Roush, T. L.; Kalashnikova, O. V.

    2011-01-01

    To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model particle size, while composition is defined by the refractive indices of minerals routinely observed in dust, including the widely used OPAC/Hess parameterization. Single-scattering properties of representative dust particle shapes are calculated using the T-matrix, Discrete Dipole Approximation and Lorenz-Mie light-scattering codes. For the parameterizations examined, MEE ranges from nearly zero to 1.2 square meters per gram, with the higher values associated with non-spheres composed of quartz and gypsum. At near-IR wavelengths, MEE for non-spheres generally exceeds those for spheres, while in the thermal IR, shape-induced changes in MEE strongly depend on volume median diameter (VMD) and wavelength, particularly for MEE evaluated at the mineral resonant frequencies. MEE spectral distributions appear to follow particle geometry and are evidence for shape dependency in the optical properties. It is also shown that non-spheres best reproduce the positions of prominent absorption peaks found in silicates. Generally, angular particles exhibit wider and more symmetric MEE spectral distribution patterns from 8-10 micrometers than those with smooth surfaces, likely due to their edge-effects. Lastly, MEE ratios allow for inferring dust optical properties across the visible-IR spectrum. We conclude the MEE of dust aerosol are significant for the parameter space investigated, and are a key component for remote sensing applications and the study of direct aerosol radiative effects.

  10. Three-year incidence of Nd:YAG capsulotomy and posterior capsule opacification and its relationship to monofocal acrylic IOL biomaterial: a UK Real World Evidence study.

    Science.gov (United States)

    Ursell, Paul G; Dhariwal, Mukesh; Majirska, Katarina; Ender, Frank; Kalson-Ray, Shoshannah; Venerus, Alessandra; Miglio, Cristiana; Bouchet, Christine

    2018-06-11

    To evaluate 3-year incidence of Nd:YAG capsulotomy and PCO and compare the effect of different IOL materials. Data were retrospectively collected from seven UK ophthalmology clinics using Medisoft electronic medical records. Eyes from patients ≥65 years undergoing cataract surgery with implantation of acrylic monofocal IOLs during 2010-2013 and 3-year follow-up were analysed. Nd:YAG capsulotomy and PCO incidence proportions were reported for 3 IOL cohorts: AcrySof, other hydrophobic and hydrophilic acrylic IOLs. Unadjusted/adjusted odds ratios (OR) of Nd:YAG capsulotomy were calculated through logistic regression for non-AcrySof cohorts versus AcrySof. A sub-group analysis in single-piece IOLs (>90% of sample eyes) was also performed. The AcrySof cohort included 13,329 eyes, non-AcrySof hydrophobic 19,025 and non-AcrySof hydrophilic 19,808. The 3-year Nd:YAG capsulotomy incidence (95% CI) for AcrySof (2.4%, 2.2-2.7%) was approximately two times lower than non-AcrySof hydrophobic IOLs (4.4%, 4.1-4.7%) and approximately fourfold lower than non-AcrySof hydrophilic IOLs (10.9%, 10.5-11.3%). Trends were similar in PCO incidence (AcrySof: 4.7%; non-AcrySof hydrophobic: 6.3%; non-AcrySof hydrophilic: 14.8%). Also in the analysis restricted to single-piece IOLs, the pattern remained (2.4% vs 5.1% vs. 10.9%, respectively). Adjusted regression analysis showed a approximately two and fivefold increased odds of Nd:YAG for non-AcrySof hydrophobic and hydrophilic acrylic IOLs respectively vs. AcrySof IOLs. Nd:YAG capsulotomy ORs were similar and remained statistically significant in the single-piece IOL sub-group. Real-world evidence shows that within 3 years following implantation, AcrySof IOLs are significantly superior in reducing Nd:YAG capsulotomy and PCO incidence compared to other hydrophilic and hydrophobic acrylic IOLs.

  11. VISUAL ACUITY AND CLINICAL REFRACTION FOLLOWING IMPLANTATION OF VARIOUS MULTIFOCAL INTRAOCULAR LENSES

    Directory of Open Access Journals (Sweden)

    N. N. Temirov

    2015-01-01

    Full Text Available Aim. To analyze visual acuity, clinical refraction, and defocusing tolerance after the implantation of monofocal IOL with rotational asymmetric optic (Lentis Mplus 313 MF compared with Acrysof ReSTOR SN6AD1.Materials and methods. Phacoemulsification was performed in a total of 194 patients (288 eyes, i.e., 144 patients (188 eyes with cataract and 50 patients (100 eyes with presbyopia and high ametropia. The patients were divided into two groups. Study group included 132 patients (194 eyes implanted with Lentis Mplus while control group included 62 patients (94 eyes implanted with Acrysof ReSTOR. Uncorrected distance (5 m, intermediate (50‑70 cm, and near (20‑40 cm visual acuity under photopic (85 cd/m2 and mesopic (8 cd/m2 conditions were measured, objective and subjective refractometry were performed, and defocusing tolerance was evaluated.Results. Postoperatively, uncorrected distance and near visual acuity was high while intermediate visual acuity was moderately low. Lentis Mplus patients had better near and intermediate visual acuity under mesopic conditions as compared with Acrysof ReSTOR patients. Emmetropia (target refraction was achieved in 90.2% of study group patients and in 87.2% of control group patients. In patients implanted with Lentis Mplus, refraction was measured by subjective method. Optimal A-constant for Lentis Mplus and Acrysof ReSTOR was 118.0 and 118.6, respectively. Under defocusing, Lentis Mplus patients had better visual acuity than Acrysof ReSTOR patients. This indirectly confirms better intermediate vision.Conclusions. Lentis Mplus provides better vision at various distances that does not almost depend on light levels and induces minimal dysphotopsia. 

  12. A study of optical design and optimization of laser optics

    Science.gov (United States)

    Tsai, C.-M.; Fang, Yi-Chin

    2013-09-01

    This paper propose a study of optical design of laser beam shaping optics with aspheric surface and application of genetic algorithm (GA) to find the optimal results. Nd: YAG 355 waveband laser flat-top optical system, this study employed the Light tools LDS (least damped square) and the GA of artificial intelligence optimization method to determine the optimal aspheric coefficient and obtain the optimal solution. This study applied the aspheric lens with GA for the flattening of laser beams using collimated laser beam light, aspheric lenses in order to achieve best results.

  13. Proceedings – Mathematical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    We define a notion of complexity for labeled oriented trees (LOTs) related to the bridge number in knot theory and prove that LOTs of complexity 2 are aspherical. We also present a class of LOTs of higher complexity which is aspherical, give an upper bound for the complexity of labeled oriented intervals and study the ...

  14. CURVAS PARALELAS EXPLÍCITAS DE LAS CURVAS CÓNICAS NO DEGENERADAS PARA EL TORNEADO CNC DE LENTES Y ESPEJOS ASFÉRICO-CÓNICOS EXPLICIT PARALLEL CURVES OF NON-DEGENERATE CONIC CURVES FOR THE TURNED CNC OF ASPHERIC-CONIC LENSES AND MIRORS

    Directory of Open Access Journals (Sweden)

    Juan Camilo Valencia

    2008-12-01

    Full Text Available Este artículo presenta el método para obtener, en coordenadas cartesianas, las líneas curvas paralelas de las curvas cónicas no degeneradas, por métodos analíticos y numéricos. Se define el offset como una función paralela a la función original a una distancia r. El offset de una cónica es importante para los procesos de fabricación de mecanismos, lentes, espejos y moldes; especialmente en el torneado con control numérico computarizado (CNC de superficies de revolución con secciones cónicas, usando buriles de diamante con punta de radio r. También se presenta una técnica refinada usando interpolación circular segmentaria para construir numéricamente el offset de una parábola, que también puede usarse como modelo para determinar el offset de la elipse y de la hipérbola.This paper presents the method to obtain, in Cartesian coordinates, the parallel curve lines of non-degenerate conical curves, by analytical and numerical methods. Offset is defined as parallel function to the original function to a distance r. Offset of a conic is important for the manufacturing processes of mechanisms, lenses, mirrors, and molds; especially in the turning with computerized numerical control (CNC of surfaces of revolution with conical sections, using diamond tools of radio r. Also a refined tip technique using segmental circular interpolation to numerically construct the parabola offset is presented, that also can be used as model to determine offsets of ellipse and hyperbola.

  15. Fast optics for the Rutherford laser compression experiments

    International Nuclear Information System (INIS)

    Micholas, D.J.

    1976-12-01

    The compression chamber optical system proposed for the Rutherford Laboratory Laser compression experiments is described. The system corrects for longitudinal spherical aberration giving a final spot size approximately 15 μm. This could theoretically be improved. The two laser beams are focused via a pair of F/1.2 aspheric lenses onto a double-pass 'clam shell' aspheric mirror system. An analysis of the lens and mirror system is given and compared with an alternative ellipsoidal system already developed. The problems of manufacturing aspheric lenses to operate at 1.06 μm are outlined and an alternative novel approach to this design given. (author)

  16. Improved Large Segmented Optics Fabrication Using Magnetorheological Finishing, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Primary mirrors for large aperture telescopes (> 10 m) are collections of smaller (1-2 m), typically hexagonal, often aspheric, optical segments. NASA's next...

  17. Fabrication Technology for X-Ray Optics and Mandrels, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has a cross-project need for large format aspheric x-ray optics, which, demonstrate exceptionally low periodic surface errors. Available technologies to both...

  18. Very High Load Capacity Air Bearing Spindle for Large Diamond Turning Machines, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Diamond turning is able to produce highly aspheric visible quality optics which can be easily aligned. Very large optical systems such as OWL and EUSO are impossible...

  19. The study of sub-surface damage distributions during grinding process on different abrasion materials

    Science.gov (United States)

    Kuo, Ching-Hsiang; Huang, Chien-Yao; Yu, Zong-Ru; Shu, Shyu-Cheng; Chang, Keng-Shou; Hsu, Wei-Yao

    2017-10-01

    The grinding process is the primary technology for curvature generation (CG) on glass optics. The higher material removal rate (MRR) leads to deeper sub-surface damage (SSD) on lens surface. The SSD must be removed by following lapping and polishing processes to ensure the lens quality. However, these are not an easy and an efficient process to remove the SSD from ground surface directly for aspheric surfaces with tens or hundreds microns departure from bestfit- sphere (BFS). An efficient fabrication procedure for large aspheric departure on glass materials must be considered. We propose 3-step fabrication procedures for aspheric surface with larger departure. 1st step is to generate a specific aspheric surface with depth less than 10 μm of SSD residual. 2nd step is to remove SSD and keep the aspheric form by using Zeeko polisher with higher MRR pad. Final step is to figure and finish the aspheric surface by using QED MRF machine. In this study, we focus on the 1st step to investigate the residual depth of SSD after grinding process on different abrasion materials. The materials of tested part are fused silica, S-NPH2, and S-PHM52. The cross grinding would be configured and depth of SSD/surface roughness would be evaluated in this study. The characteristic of SSD could be observed after etching by confocal microscope. The experimental results show the depth of SSD below 31.1 μm with #400 grinding wheel. And the near 10 μm depth of SSD would be achieved with #1,000 grinding wheel. It means the aspherization polishing on large parts with large departure from best fit sphere would be replaced. The fabrication of large aspheric part would be efficient.

  20. Využití FEM lešticí technologie při leštění optických ploch

    Czech Academy of Sciences Publication Activity Database

    Procháska, František; Polák, Jaroslav; Tomka, David; Šubert, E.

    2012-01-01

    Roč. 57, 11-12 (2012), s. 321-324 ISSN 0447-6441. [OaM 2012 International Conference on Optics and Measurement. Liberec, 16.10.2012-18.10.2012] R&D Projects: GA MŠk(CZ) ED2.1.00/03.0079 Institutional research plan: CEZ:AV0Z20430508 Keywords : asphere polishing * CCM polishing * asphere measurement Subject RIV: BH - Optics, Masers, Lasers

  1. From red giants to planetary nebulae: Asymmetries, dust, and polarization

    International Nuclear Information System (INIS)

    Johnson, J.J.

    1990-01-01

    In order to investigate the development of aspherical planetary nebulae, polarimetry was obtained for a group of planetary nebulae and for objects that will evolve into planetary nebulae, i.e., red giants, late asymptotic giant branch (AGB) objects, proto-planetary nebulae, and young planetary nebulae. To study the dust around the objects in our sample, we also used data from the Infrared Astronomy Satellite (IRAS) mission. The youngest objects in our survey, red giants, had the hottest dust temperatures while planetary nebulae had the coolest. Most of the objects were intrinsically polarized, including the red giants. This indicated that the circumstellar dust shells of these objects were aspherical. Both carbon- and oxygen-rich objects could be intrinsically polarized. The intrinsic polarizations of a sample of our objects were modeled using an ellipsoidal circumstellar dust shell. The findings of this study suggest that the asphericities that lead to an aspherical planetary nebula originate when a red giant begins to undergo mass loss. The polarization and thus the asphericity as the star evolves, with both reaching a maximum during the proto-planetary nebula stage. The circumstellar dust shell will dissipate after the proto-planetary nebulae stage since no new material is being added. The polarization of planetary nebulae will thus be low. In the most evolved planetary nebulae, the dust has either been destroyed or dissipated into the interstellar medium. In these objects no polarization was observed

  2. Comparison of real and computer-simulated outcomes of LASIK refractive surgery

    Science.gov (United States)

    Cano, Daniel; Barbero, Sergio; Marcos, Susana

    2004-06-01

    Computer simulations of alternative LASIK ablation patterns were performed for corneal elevation maps of 13 real myopic corneas (range of myopia, -2.0 to -11.5 D). The computationally simulated ablation patterns were designed with biconic surfaces (standard Munnerlyn pattern, parabolic pattern, and biconic pattern) or with aberrometry measurements (customized pattern). Simulated results were compared with real postoperative outcomes. Standard LASIK refractive surgery for myopia increased corneal asphericity and spherical aberration. Computations with the theoretical Munnerlyn ablation pattern did not increase the corneal asphericity and spherical aberration. The theoretical parabolic pattern induced a slight increase of asphericity and spherical aberration, explaining only 40% of the clinically found increase. The theoretical biconic pattern controlled corneal spherical aberration. Computations showed that the theoretical customized pattern can correct high-order asymmetric aberrations. Simulations of changes in efficiency due to reflection and nonnormal incidence of the laser light showed a further increase in corneal asphericity. Consideration of these effects with a parabolic pattern accounts for 70% of the clinical increase in asphericity.

  3. Effects of blue light-filtering intraocular lenses on the macula, contrast sensitivity, and color vision after a long-term follow-up.

    Science.gov (United States)

    Kara-Junior, Newton; Espindola, Rodrigo F; Gomes, Beatriz A F; Ventura, Bruna; Smadja, David; Santhiago, Marcony R

    2011-12-01

    To evaluate the possible side effects and potential protection 5 years after implantation of an intraocular lens (IOL) with a blue-light filter (yellow tinted). Ophthalmology Department, University of São Paulo, São Paulo, Brazil. Prospective randomized clinical study. Patients with bilateral visually significant cataract randomly received an ultraviolet (UV) and blue light-filtering IOL (Acrysof Natural SN60AT) in 1 eye and an acrylic UV light-filtering only IOL (Acrysof SA60AT) in the fellow eye. The primary outcome measures were contrast sensitivity, color vision, and macular findings 5 years after surgery. The study enrolled 60 eyes of 30 patients. There were no significant clinical or optical coherence tomography findings in terms of age-related macular degeneration in any eye. There were no statistically significant differences in central macular thickness between the 2 IOL groups (P=.712). There were also no significant between-group differences under photopic or scotopic conditions at any spatial frequency studied. No statistically significant differences in the color discrimination test were found between the 2 IOL groups (P=.674). After 5 years, there were no significant differences in color perception, scotopic contrast sensitivity, or photopic contrast sensitivity between the blue light-filtering (yellow-tinted) IOL and the IOL with a UV-light filter only (untinted). The potential advantage of the tinted IOL in providing protection to macular cells remains unclear. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  4. Finishing of precision generated metal optical components

    International Nuclear Information System (INIS)

    Baker, P.C.; Sonderman, J.B.

    1975-08-01

    Diamond turning and precision generation of aspheric metal surfaces has promoted a change in lapping techniques due to the extremely close figure tolerances and surface finishes that have been achieved. Special tooling, diamond abrasive, silicon oil and special techniques used to polish the unusual aspheric figures are described. The studies include small flat diamond turned samples of copper, electroplated copper, electroplated silver, electroplated nickel and silver as well as large aspheres such as an f/0.75, 35 cm dia copper ellipse. Results from cleaning studies on flat samples using ultrasonics and vapor degreasers are also summarized. Interferograms of wavefront distortion and analysis of focal volume are included as well as 10.6 μm reflectivity and a summary of laser damage experiments. (TFD)

  5. Digital Moiré based transient interferometry and its application in optical surface measurement

    Science.gov (United States)

    Hao, Qun; Tan, Yifeng; Wang, Shaopu; Hu, Yao

    2017-10-01

    Digital Moiré based transient interferometry (DMTI) is an effective non-contact testing methods for optical surfaces. In DMTI system, only one frame of real interferogram is experimentally captured for the transient measurement of the surface under test (SUT). When combined with partial compensation interferometry (PCI), DMTI is especially appropriate for the measurement of aspheres with large apertures, large asphericity or different surface parameters. Residual wavefront is allowed in PCI, so the same partial compensator can be applied to the detection of multiple SUTs. Excessive residual wavefront aberration results in spectrum aliasing, and the dynamic range of DMTI is limited. In order to solve this problem, a method based on wavelet transform is proposed to extract phase from the fringe pattern with spectrum aliasing. Results of simulation demonstrate the validity of this method. The dynamic range of Digital Moiré technology is effectively expanded, which makes DMTI prospective in surface figure error measurement for intelligent fabrication of aspheric surfaces.

  6. Lens decenter and tilt measurement by interferogram

    Science.gov (United States)

    Hung, Min-Wei; Wu, Wen-Hong; Huang, Kuo-Cheng

    2009-11-01

    For the recent years, the vigorous development of the electro-optic industry, particularly the digital camera and the cellular phone camera, has placed a larger and larger demand for the optical devices. Among the optical lens, the aspherical optical lens plays the key component because the aspherical lens may provide better imaging quality then the spherical lens does. For the manufacturing reason, the aspherical lens is prone to a decenter or tilt issue with respect to the optical axes of its two surfaces. To measure decenter and tile error specifically would help to obviate the deficient lens, but most of the present measuring method can't provide this function. This paper proposed a new method to specifically measure the decenter and tile of lens by observing the interferogram of each surface. And the corresponding measuring instrument, which contains interferometer and motion stages, was introduced as well.

  7. Universal shape characteristics for the mesoscopic star-shaped polymer via dissipative particle dynamics simulations

    Science.gov (United States)

    Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu; von Ferber, C.

    2018-05-01

    In this paper we study the shape characteristics of star-like polymers in various solvent quality using a mesoscopic level of modeling. The dissipative particle dynamics simulations are performed for the homogeneous and four different heterogeneous star polymers with the same molecular weight. We analyse the gyration radius and asphericity at the poor, good and θ-solvent regimes. Detailed explanation based on interplay between enthalpic and entropic contributions to the free energy and analyses on of the asphericity of individual branches are provided to explain the increase of the apsphericity in θ-solvent regime.

  8. Optical design and performance analysis of a 25 m class telescope with a segmented spherical primary

    DEFF Research Database (Denmark)

    Owner-Petersen, Mette

    1996-01-01

    The basic design and an analysis of the performance possibilities of a 25 m class optical telescope are presented here. The configuration consists of a 28 m segmented spherical primary M1 followed by three highly aspherical corrective mirrors M2, M3 and M4 which also deviate from cartesian shape...... sag and windbuffeting. Several types of aspherical figuring of M2, M3 and M4 all resulting in a field performance better than characterized by a RMS spotradius smaller than 0.1 arcseconds within a full FOV of 21 arcminutes are presented....

  9. cD galaxy formation and dissipationless collapse

    International Nuclear Information System (INIS)

    Rhee, G.; Roos, N.

    1990-01-01

    There is strong new evidence that first-ranked galaxies are aligned with their parent cluster and with the direction of the nearest neighbour cluster (scale 15 h -1 Mpc) and that the average ellipticity of first-ranked ellipticals is a strongly increasing function of radius. The alignment effect is limited to first-ranked galaxies and is stronger for cD and gE galaxies than for first-ranked galaxies of later type. In hierarchical clustering scenarios like the cold dark matter theory, clusters of galaxies are expected to have moderate asphericity. We present numerical results of a study of the dissipationless collapse of moderately aspherical systems. (author)

  10. Instrumental studies on silicone oil adsorption to the surface of intraocular lenses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chun Ho [Lab. of Tissue Engineering, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Joo, Choun-Ki [Department of Ophthalmology and Visual Science, Medical College of Catholic University, Seoul 137-701 (Korea, Republic of); Chun, Heung Jae, E-mail: chunhj@catholic.ac.kr [Institute of Cell and Tissue Engineering, Medical College of Catholic University, Seoul 137-701 (Korea, Republic of); Yoo, Bok Ryul [Organosilicone Chemistry Laboratory, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Noh, Dong Il; Shim, Young Bock [Research Institute of Biomedical Engineering, Korea Bone Bank Co. Ltd., Seoul 153-782 (Korea, Republic of)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer It was found that PHEMA and Acrysof IOLs possess silicone oil repellant ability. Black-Right-Pointing-Pointer The residual silicone oil was detected on the surfaces of PMMA and silicone IOLs. Black-Right-Pointing-Pointer XPS studies showed that silicone oil coverage of PMMA lenses was 12%. Black-Right-Pointing-Pointer Silicone oil covered the entire surface of the silicone IOLs. - Abstract: The purpose of this study was to examine the degree of adherence of silicone oil to various intraocular lenses (IOLs) through comparison of the physico-chemical properties of the oil and IOLs. Four kinds of IOLs comprising various biomaterials were examined: PMMA (720A Trade-Mark-Sign ), PHEMA (IOGEL 1103 Trade-Mark-Sign ), Acrysof (MA60BM Trade-Mark-Sign ), and silicone (SI30NB Trade-Mark-Sign ). Each lens was immersed in silicone oil or carboxylated silicone (CS-PDMS) oil for 72 h. For determination of the changes in chemical and elemental compositions on the surfaces of IOLs caused by the contact with silicone oil, IOLs were washed and rinsed with n-pentane to remove as much of the adsorbed silicone oil as possible, then subjected to Fourier transform infrared spectroscopic (FTIR) and X-ray photoelectron spectroscopic (XPS) analyses. The results of FTIR studies strongly indicate that washing with n-pentane completely removed the adhered silicone oil on the surfaces of PHEMA and Acrysof IOLs, whereas the residual silicone oil was detected on the surfaces of PMMA and silicone IOLs. XPS studies showed that silicone oil coverage of PMMA lenses was 12%, even after washing with n-pentane. In the case of silicone IOLs, the relative O1s peak area of carboxyl group in the residual CS-PDMS oil was found to be {approx}2.7%. Considering that 2.8% carboxyl group-substituted silicone oil was used in the present study, CS-PDMS oil covered the entire surface of the silicone IOLs.

  11. Comparison between bilateral implantation of a trifocal intraocular lens and blended implantation of two bifocal intraocular lenses

    Directory of Open Access Journals (Sweden)

    Vilar C

    2017-08-01

    Full Text Available César Vilar,1,2 Wilson Takashi Hida,1–3 André Lins de Medeiros,1,2 Klayny Rafaella Pereira Magalhães,2 Patrick Frensel de Moraes Tzelikis,1,2 Mario Augusto Pereira Dias Chaves,2,4 Antônio Francisco Pimenta Motta,2,3 Pedro Carlos Carricondo,1–3 Milton Ruiz Alves,3 Walton Nosé5 1Cataract Division, Brasília Ophthalmologic Hospital (HOB, Brasília-DF, Brazil; 2Renato Ambrosio Ophthalmologic Research Center (CEORA, 3Ophthalmology Department, São Paulo University – USP, São Paulo-SP, Brazil; 4Cataract Division, ProVisão, João Pessoa-PB, Brazil; 5Ophthalmology Department, Paulista Medical School – UNIFESP, São Paulo-SP, Brazil Purpose: To compare visual outcomes and performance between bilateral implantation of a diffractive trifocal intraocular lens (IOL Acrysof®PanOptix® TFNT00 and blended implantation of two different near add power bifocal IOLs: Acrysof® Restor® SV25T0 in dominant eye and Acrysof® Restor® SN6AD1 in the nondominant eye.Methods: This prospective, nonrandomized, consecutive and comparative study assessed 20 patients (40 eyes who had bilateral cataract surgery performed using the IOLs described. Patients were divided into groups, bilateral trifocal implant and blended implant. Evaluation included measurement of binocular uncorrected and corrected distance visual acuity at 4 m (UDVA, CDVA and uncorrected intermediate (60 cm and near (at 40 cm visual acuity; contrast sensitivity (CS and visual defocus curve.Results: Postoperative CDVA comparison showed no statistical significance between groups. UDVA was significantly better in the trifocal groups. Under photopic conditions, the trifocal group had better CS in higher frequencies with and without glare. The binocular defocus curve demonstrated a trifocal behavior in both groups, with the bilateral trifocal group exhibiting better performance for intermediate vision.Conclusion: Both lens combinations were able to provide good near, intermediate and distance vision

  12. Objective quality of vision in presbyopic and non-presbyopic patients after pseudoaccommodative advanced surface ablation.

    Science.gov (United States)

    Cantú, Roberto; Rosales, Marco A; Tepichín, Eduardo; Curioca, Andrée; Montes, Víctor; Ramirez-Zavaleta, J Gustavo

    2005-01-01

    To analyze the objective quality of vision at 6 months postoperatively after pseudoaccommodative (presbyopic) advanced surface ablation (PASA). The study comprised 62 eyes of 35 patients with 6-month follow-up that underwent primary or secondary treatments using PASA. Pre- and postoperative results of distance and near uncorrected visual acuity (UCVA), spherical aberration (coefficient of the Z12 Zernike polynomial), and the asphericity (Q) index were reviewed. The corresponding wavefront maps (total, low, and high order aberrations) and the corresponding point spread function and modulation transfer function (MTF) were also calculated. Our results show that PASA improves distance and near mean UCVA, increases negative spherical aberration and negative asphericity index, and improves the corresponding MTF. Pseudoaccommodative advanced surface ablation is a promising approach for the surgical correction of presbyopia with distance refractive error (myopia and hyperopia with or without astigmatism). This PASA technique could theoretically be used in non-presbyopic patients with refractive error or post cataract patients with monofocal intraocular lenses. The increase in negative spherical aberration and asphericity/eccentricity index seems to increase the depth of focus of the eye, improving the near vision and compensating the age-related lens changes. Rather than creating a multifocal cornea, PASA appears to create an improved aspheric (prolate) ablation profile.

  13. Návrh algoritmu pro řízení tvarových korekcí pětiosého obráběcího centra.

    Czech Academy of Sciences Publication Activity Database

    Beneš, Jiří; Procháska, František; Matoušek, Ondřej

    2017-01-01

    Roč. 62, 11-12 (2017), s. 296-298 ISSN 0447-6441 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : spherical * aspherical * surface * correction * correction data * grinding * generating shape Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics)

  14. Optický návrh fotografické komory s elipsoidálním primárním zrcadlem. 1.část.

    Czech Academy of Sciences Publication Activity Database

    Rail, Zdeněk; Pintr, Pavel; Melich, Zbyněk; Vápenka, David

    2017-01-01

    Roč. 62, č. 5 (2017), s. 165-167 ISSN 0447-6441 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : The Dall-Kirkham telescope * wide field camera * ellipsoidal mirror * lens corrector * aspherical plates Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics)

  15. Optický návrh fotografické komory s elipsoidálním primárním zrcadlem. 2.část

    Czech Academy of Sciences Publication Activity Database

    Rail, Zdeněk; Pintr, Pavel; Melich, Zbyněk; Vápenka, David

    2017-01-01

    Roč. 62, 6-7 (2017), s. 185-186 ISSN 0447-6441 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : The Dall-Kirkham telescope * wide field camera * ellipsoidal mirror * lens corrector * aspherical plates Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics)

  16. Non-contact measurement machine for freeform optics

    NARCIS (Netherlands)

    Henselmans, R.

    2009-01-01

    The performance of high-precision optical systems using spherical optics is limited by aberrations. By applying aspherical and freeform optics, the geometrical aberrations can be reduced or eliminated while at the same time also reducing the required number of components, the size and the weight of

  17. Transferability of glass lens molding

    Science.gov (United States)

    Katsuki, Masahide

    2006-02-01

    Sphere lenses have been used for long time. But it is well known that sphere lenses theoretically have spherical aberration, coma and so on. And, aspheric lenses attract attention recently. Plastic lenses are molded easily with injection machines, and are relatively low cost. They are suitable for mass production. On the other hand, glass lenses have several excellent features such as high refractive index, heat resistance and so on. Many aspheric glass lenses came to be used for the latest digital camera and mobile phone camera module. It is very difficult to produce aspheric glass lenses by conventional process of curve generating and polishing. For the solution of this problem, Glass Molding Machine was developed and is spreading through the market. High precision mold is necessary to mold glass lenses with Glass Molding Machine. The mold core is ground or turned by high precision NC aspheric generator. To obtain higher transferability of the mold core, the function of the molding machine and the conditions of molding are very important. But because of high molding temperature, there are factors of thermal expansion and contraction of the mold and glass material. And it is hard to avoid the factors. In this session, I introduce following items. [1] Technology of glass molding and the machine is introduced. [2] The transferability of glass molding is analyzed with some data of glass lenses molded. [3] Compensation of molding shape error is discussed with examples.

  18. A study on the optical parts for a semiconductor laser module

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jun-Girl; Lee, Dong-Kil; Kim, Yang-Gyu; Lee, Kwang-Hoon; Park, Young-Sik [Korea Photonics Technology Institute, Gwangju (Korea, Republic of); Jang, Kwang-Ho [Hanvit Optoline, Gwangju (Korea, Republic of); Kang, Seung-Goo [COSET, Gwangju (Korea, Republic of)

    2014-11-15

    A semiconductor laser module consists of a LD (laser diode) chip that generates a laser beam, two cylindrical lenses to collimate the laser beam, a high-reflection mirror to produce a large output by collecting the laser beam, a collimator lens to guide the laser beam to an optical fiber and a protection filter to block reflected laser light that might damage the LD chip. The cylindrical lenses used in a semiconductor laser module are defined as FACs (fast axis collimators) and SACs (slow axis collimators) and are attached to the system module to control the shape of the laser beam. The FAC lens and the SAC lens are made of a glass material to protect the lenses from thermal deformation. In addition, they have aspheric shapes to improve optical performances. This paper presents a mold core grinding process for an asymmetrical aspheric lens and a GMP (glass molding press), what can be used to make aspheric cylindrical lenses for use as FACs or SACs, and a protection filter made by using IAD (ion-beam-assisted deposition). Finally, we developed the aspheric cylindrical lenses and the protection filter for a 10-W semiconductor laser module.

  19. Optics of the human cornea influence the accuracy of stereo eye-tracking methods: a simulation study

    NARCIS (Netherlands)

    Barsingerhorn, A.D.; Boonstra, F.N.; Goossens, H.H.L.M.

    2017-01-01

    Current stereo eye-tracking methods model the cornea as a sphere with one refractive surface. However, the human cornea is slightly aspheric and has two refractive surfaces. Here we used ray-tracing and the Navarro eye-model to study how these optical properties affect the accuracy of different

  20. Metodika měření tvaru asférických prvků jakožto součást optické výroby

    Czech Academy of Sciences Publication Activity Database

    Procháska, František; Michal ml., S.; Melich, Radek; Psota, Pavel

    2015-01-01

    Roč. 60, č. 2 (2015), s. 81-84 ISSN 0447-6441 R&D Projects: GA MŠk(CZ) LO1206; GA TA ČR(CZ) TA03010843 Institutional support: RVO:61389021 Keywords : Aspheric surface measurement Subject RIV: JS - Reliability ; Quality Management, Testing http://jmo.fzu.cz/

  1. Využití digitální holografie pro měření tvarů broušených optických ploch

    Czech Academy of Sciences Publication Activity Database

    Psota, Pavel; Lédl, Vít; Vojtíšek, Petr; Doleček, Roman

    2015-01-01

    Roč. 60, č. 3 (2015), s. 101-104 ISSN 0447-6441 R&D Projects: GA TA ČR(CZ) TA03010893 Institutional support: RVO:61389021 Keywords : Digital Holography * Form inspection * Asphere * Grinded surfaces * Multivawelength * Least square * contouring Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://jmo.fzu.cz/

  2. Novel Optical Methods for Identification, Imaging, and Preservation of the Cavernous Nerves Responsible for Penile Erections during Prostate Cancer Surgery

    Science.gov (United States)

    2010-03-01

    ICP) measurements. To assess ICP, the shaft of the penis was denuded of skin and the left crural region was cannulated with a 23-G needle connected...software. Rod Mirror Aspheric Lens Ferrule Fiber Linear Stage to PC Fiber Rod Housing Optics 5-mm-ID Port Probe Handle Probe Stem Enlarged View of

  3. Pigment dispersion and chronic intraocular pressure elevation after sulcus placement of 3-piece acrylic intraocular lens.

    Science.gov (United States)

    Almond, M Camille; Wu, Michael C; Chen, Philip P

    2009-12-01

    A 55-year-old man had phacoemulsification and implantation of a 3-piece acrylic intraocular lens (IOL) (AcrySof MA60AC) in the right eye. One month postoperatively, the intraocular pressure (IOP) was 48 mm Hg and peripheral transillumination defects were noted in the iris circumferentially, with the IOL optic edge visible as a silhouette. Gonioscopy showed dense pigmentation of the trabecular meshwork in the right eye, but in the left eye, only mild trabecular meshwork pigment was seen, along with a concave peripheral iris insertion. At 21 months, the right eye required 3 medications for IOP control. While pigment dispersion has been widely reported after placement of 1-piece acrylic IOLs in the ciliary sulcus, we conclude that in susceptible individuals with a concave peripheral iris insertion, pigment dispersion can occur with sulcus placement of a 3-piece acrylic model despite its thinner optic and angulated haptics.

  4. Evaluation of rotation and visual outcomes after implantation of monofocal and multifocal toric intraocular lenses.

    Science.gov (United States)

    Garzón, Nuria; Poyales, Francisco; de Zárate, Begoña Ortíz; Ruiz-García, Jose Luis; Quiroga, Juan Antonio

    2015-02-01

    To evaluate rotational stability and its influence on postoperative visual acuity of different monofocal and multifocal toric intraocular lenses (IOLs). A prospective interventional study was designed. Ninety-one patients with a mean age of 71.65 ± 11.82 years were implanted with toric IOLs after phacoemulsification. Three monofocal toric IOLs (the Lentis LT [Oculentis, Berlin, Germany], enVista [Bausch & Lomb, Rochester, NY], and AcrySof IQ [Alcon Laboratories, Inc., Fort Worth, TX]) and one multifocal toric IOL (AcrySof IQ ReSTOR; Alcon Laboratories, Inc.) were implanted. Preoperative and postoperative images were taken to calculate the misalignment due to the marking method. To evaluate rotation in the different follow-up visits, another photograph was taken 1 hour and 1, 7 and 30 days postoperatively. Refraction, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity were measured 30 days postoperatively. Postoperative UDVA was 0.1 logMAR or better in 64.6% of eyes implanted with monofocal IOLs and 46.4% of eyes implanted with multifocal IOLs. The enVista toric IOL showed the best UDVA compared to the other monofocal IOLs, with 81% of eyes with 0.1 logMAR or better. The mean misalignment in the total group studied was 0.07° ± 0.60°; 69.6% of monofocal IOLs and 67.9% of multifocal IOLs showed less than 5° of rotation. A correlation was found between postoperative UDVA and rotation in the monofocal and multifocal IOLs implanted (r = 0.439 [P < .011] and = 0.787 [P = .001], respectively). At 1 month postoperatively, UDVA was slightly more affected by IOL rotation in multifocal than monofocal toric IOLs. The marking method was also effective. Copyright 2015, SLACK Incorporated.

  5. Comparison of clinical outcomes between limbal relaxing incisions and toric intraocular lenses in eyes with astigmatic corneas

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2014-01-01

    Full Text Available Objective: To compare refractive and vectorial outcomes of limbal relaxing incisions (LRI versus toric intraocular lenses (IOL in the treatment of preexisting corneal astigmatism at the time of phacoemulsification. Methods: This longitudinal observational case series assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted in two groups: one assigned to receive AcrySof Toric™ IOL in both eyes, and another one assigned to have AcrySof Natural™ IOL associated with LRI, also in both eyes. All patients were re-evaluated, postoperatively, at 1, 3 and 6 months, when refractive astigmatism analysis was performed using vectorial methods proposed by Thibos. Variability of outcomes within each group and between groups were assessed and compared. Results: Manifest refractive cylinder, in diopters (D, as means ± standard deviation, in the LRI group for 1-month, 3-month and 6-month re-evalutions were respectively -0.66 ± 0.30; -0.70 ± 0.21 and -0.74 ± 0.26 when compared to -0.58 ± 0.24; -0.63 ± 0.20, and -0.62 ± 0.17 in the toric IOL group. (p value ≥ 0.06. Vectorial analysis evidenced greater astigmatism reduction in the toric IOL group in the 6th postoperative month, when postoperative mean astigmatic power vector was 0.31 D, when compared to 0.37 D in the LRI group (p value = 0.00. Conclusions: A trend of slightly better refractive outcomes favoring toric IOL group was seen, although such a trend was not statistically significant. Vectorial analysis, however, suggests that the use of toric IOL may constitute a more advantageous approach in the treatment of pre-existing corneal astigmatism, simultaneously with phacoemulsification.

  6. From red giant to planetary nebula - Dust, asymmetry, and polarization

    International Nuclear Information System (INIS)

    Johnson, J.J.; Jones, T.J.

    1991-01-01

    The polarization characteristics of stars in the stages of evolution from red giant to planetary nebula are investigated. Polarization is found to be a characteristic of the majority of these stars. The maximum observed polarization increases with age as the star evolves up the asymptotic giant branch (AGB) to the protoplanetary nebula phase, where the polarization reaches a maximum. The polarization then decreases as the star further evolves into a planetary nebula. These results indicate that aspherical mass loss is likely to be a continual feature of the late stages of stellar evolution, maintaining a clear continuity throughout the life of a star from the moment it first develops a measurable dust shell. The aspherical morphology seen in planetary nebulae has its origin in an intrinsic property of the star that is present at least as early as its arrival at the base of the AGB. 77 refs

  7. Fiber-Coupled Wide Field of View Optical Receiver for High Speed Space Communication

    Science.gov (United States)

    Suddath, Shannon N.

    Research groups at NASA Glenn Research Center are interested in improving data rates on the International Space Station (ISS) using a free-space optical (FSO) link. However, known flexure of the ISS structure is expected to cause misalignment of the FSO link. Passive-control designs for mitigating misalignment are under investigation, including using a fiber-bundle for improved field of view. The designs must overcome the obstacle of coupling directly to fiber, rather than a photodetector, as NASA will maintain the use of small form-factor pluggable optical transceivers (SFPs) in the ISS network. In this thesis, a bundle-based receiver capable of coupling directly to fiber is designed, simulated, and tested in lab. Two 3-lens systems were evaluated for power performance in the lab, one with a 20 mm focal length aspheric lens and the other with a 50 mm focal length aspheric lens. The maximum output power achieved was 8 muW.

  8. Error reduction techniques for measuring long synchrotron mirrors

    International Nuclear Information System (INIS)

    Irick, S.

    1998-07-01

    Many instruments and techniques are used for measuring long mirror surfaces. A Fizeau interferometer may be used to measure mirrors much longer than the interferometer aperture size by using grazing incidence at the mirror surface and analyzing the light reflected from a flat end mirror. Advantages of this technique are data acquisition speed and use of a common instrument. Disadvantages are reduced sampling interval, uncertainty of tangential position, and sagittal/tangential aspect ratio other than unity. Also, deep aspheric surfaces cannot be measured on a Fizeau interferometer without a specially made fringe nulling holographic plate. Other scanning instruments have been developed for measuring height, slope, or curvature profiles of the surface, but lack accuracy for very long scans required for X-ray synchrotron mirrors. The Long Trace Profiler (LTP) was developed specifically for long x-ray mirror measurement, and still outperforms other instruments, especially for aspheres. Thus, this paper focuses on error reduction techniques for the LTP

  9. Optical system design, analysis, and production for advanced technology systems; Proceedings of the Meeting, Innsbruck, Austria, Apr. 15-17, 1986

    Science.gov (United States)

    Fischer, Robert E. (Editor); Rogers, Philip J. (Editor)

    1986-01-01

    The present conference considers topics in the fields of optical systems design software, the design and analysis of optical systems, illustrative cases of advanced optical system design, the integration of optical designs into greater systems, and optical fabrication and testing techniques. Attention is given to an extended range diffraction-based merit function for lens design optimization, an assessment of technologies for stray light control and evaluation, the automated characterization of IR systems' spatial resolution, a spectrum of design techniques based on aberration theory, a three-field IR telescope, a large aperture zoom lens for 16-mm motion picture cameras, and the use of concave holographic gratings as monochomators. Also discussed are the use of aspherics in optical systems, glass choice procedures for periscope design, the fabrication and testing of unconventional optics, low mass mirrors for large optics, and the diamond grinding of optical surfaces on aspheric lens molds.

  10. Surface loading of a viscoelastic earth-I. General theory

    Science.gov (United States)

    Tromp, Jeroen; Mitrovica, Jerry X.

    1999-06-01

    We present a new normal-mode formalism for computing the response of an aspherical, self-gravitating, linear viscoelastic earth model to an arbitrary surface load. The formalism makes use of recent advances in the theory of the Earth's free oscillations, and is based upon an eigenfunction expansion methodology, rather than the tradi-tional Love-number approach to surface-loading problems. We introduce a surface-load representation theorem analogous to Betti's reciprocity relation in seismology. Taking advantage of this theorem and the biorthogonality of the viscoelastic modes, we determine the complete response to a surface load in the form of a Green's function. We also demonstrate that each viscoelastic mode has its own unique energy partitioning, which can be used to characterize it. In subsequent papers, we apply the theory to spherically symmetric and aspherical earth models.

  11. Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

    Science.gov (United States)

    Britcliffe, M. J.; Hoppe, D. J.

    2001-01-01

    The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

  12. Femoroacetabular impingement

    International Nuclear Information System (INIS)

    Anderson, Suzanne E.; Siebenrock, Klaus Arno; Tannast, Moritz

    2012-01-01

    Femoroacetabular impingement (FAI) is a pathomechanical concept describing the early and painful contact of morphological changes of the hip joint, both on the acetabular, and femoral head sides. These can lead clinically to symptoms of hip and groin pain, and a limited range of motion with labral, chondral and bony lesions. Pincer impingement generally involves the acetabular side of the joint where there is excessive coverage of the acetabulum, which may be focal or more diffuse. There is linear contact of the acetabulum with the head/neck junction. Cam impingement involves the femoral head side of the joint where the head is associated with bony excrescences and is aspheric. The aspheric femoral head jams into the acetabulum. Imaging appearances are reviewed below. This type is evident in young males in the second and third decades. The main features of FAI are described.

  13. Simplied formula for the illuminance in an optical system

    International Nuclear Information System (INIS)

    Burkhard, D.G.; Shealy, D.L.

    1981-01-01

    A formula is derived for the illuminance at any surface in an optical system. By tracing a single ray one can compute the flux density at the image plane or any other position along the ray. The formula involves the ratio of the products of the principal curvatures of the wave front as it approaches each surface to products of the same qualitities after the wave front is refracted at each surface. A procedure is presented for determining the required principal curvatures by generalizing the Coddinton equations to multiple surfaces for both meridional and skew rays. Results are applicable to both sphreical and aspherical surfaces. Since principal radii of curvature specify points on the caustic surfaces, the formula and computation procedure automatically yields the equations for caustic surfaces as a by-product. To illustrate the computation procedure the illuminance and caustic surfaces are derived for an aspherical singlet

  14. Next-generation fabrication technologies for optical pickup devices in high-density optical disk storage systems

    Science.gov (United States)

    Hosoe, Shigeru

    1999-05-01

    This paper shows a direction of friction technologies to make aspherical plastic objective lens with higher optical performance for high density optical disk storage systems. Specifically, a low birefringence and low water absorption (less than 0.1%) optical resin, low tool abrasion mold material, high circularity diamond tool which nose circularity is less than 30 nm, and 1 nm axis resolution precision lathe which tool position is stabilized against drift by environmental change are referred. Cut optical surface of a mold sample was constantly attained in less than 5 nmRtm surface roughness. Using these new technologies, aspherical plastic objective lens (NA0.6) for DVD which wave aberration is less than 35 m (lambda) rms was realized.

  15. Optical Design of the Camera for Transiting Exoplanet Survey Satellite (TESS)

    Science.gov (United States)

    Chrisp, Michael; Clark, Kristin; Primeau, Brian; Dalpiaz, Michael; Lennon, Joseph

    2015-01-01

    The optical design of the wide field of view refractive camera, 34 degrees diagonal field, for the TESS payload is described. This fast f/1.4 cryogenic camera, operating at -75 C, has no vignetting for maximum light gathering within the size and weight constraints. Four of these cameras capture full frames of star images for photometric searches of planet crossings. The optical design evolution, from the initial Petzval design, took advantage of Forbes aspheres to develop a hybrid design form. This maximized the correction from the two aspherics resulting in a reduction of average spot size by sixty percent in the final design. An external long wavelength pass filter was replaced by an internal filter coating on a lens to save weight, and has been fabricated to meet the specifications. The stray light requirements were met by an extended lens hood baffle design, giving the necessary off-axis attenuation.

  16. Spatio-kinematic modelling: Testing the link between planetary nebulae and close binaries

    OpenAIRE

    Jones, David; Tyndall, Amy A.; Huckvale, Leo; Prouse, Barnabas; Lloyd, Myfanwy

    2011-01-01

    It is widely believed that central star binarity plays an important role in the formation and evolution of aspherical planetary nebulae, however observational support for this hypothesis is lacking. Here, we present the most recent results of a continuing programme to model the morphologies of all planetary nebulae known to host a close binary central star. Initially, this programme allows us to compare the inclination of the nebular symmetry axis to that of the binary plane, testing the theo...

  17. COMPARISON OF DIVERSITY OF TYPE IIB SUPERNOVAE WITH ASYMMETRY IN CASSIOPEIA A USING LIGHT ECHOES

    Energy Technology Data Exchange (ETDEWEB)

    Finn, Kieran; Bianco, Federica B.; Modjaz, Maryam; Liu, Yu-Qian [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States); Rest, Armin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2016-10-20

    We compare the diversity of spectral line velocities in a large sample of type IIb supernovae (SNe IIb) with the expected asphericity in the explosion, as measured from the light echoes (LEs) of Cassiopeia A (Cas A), which was a historical galactic SN IIb. We revisit the results of Rest et al., who used LEs to observe Cas A from multiple lines of sight and hence determine its asphericity, as seen in the velocity of three spectral lines (He i λ 5876, H α , and the Ca ii near-infrared (NIR) triplet). We confirm and improve on this measurement by reproducing the effect of the LEs in the spectra of several extragalactic SNe IIb found in the literature as well as mean SN IIb spectra recently created by Liu et al. and comparing these to the observed light echo spectra of Cas A, including their associated uncertainties. In order to quantify the accuracy of this comparison, we smooth the light echo spectra of Cas A using Gaussian processes and use a Monte Carlo method to measure the absorption velocities of these three features in the spectra. We then test the hypothesis that the diversity of ejecta velocities seen in SNe IIb can be explained by asphericity. We do this by comparing the range of velocities seen in the different LEs, and hence different lines of sight, of Cas A to that seen in the population of SNe IIb. We conclude that these two ranges are of the same order and thus asphericity could be enough to explain the diversity in the expansion velocity alone.

  18. Compensation for gravitational sag of bent mirror

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China); Shu, De-ming [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, Aiguo, E-mail: aiguo.li@sinap.ac.cn [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China)

    2017-05-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  19. Compensation for gravitational sag of bent mirror

    International Nuclear Information System (INIS)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai; Shu, De-ming; Li, Aiguo

    2017-01-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  20. Seismic Study of Magnetic Field in the Solar Interior H. M. Antia

    Indian Academy of Sciences (India)

    It is clear that the surface term is well correlated with the observed magnetic flux at the solar surface. Thus it is quite likely that observed asphericity near the solar surface is actually due to magnetic field. The left panel in Fig. 3 shows δc2/c2 obtained using MDI data. These results clearly show some temporal variations, but a ...

  1. ADVANTAGES OF DIFFRACTIVE OPTICAL ELEMENTS APPLICATION IN SIMPLE OPTICAL IMAGING SYSTEMS

    Directory of Open Access Journals (Sweden)

    N. D. Zoric

    2015-01-01

    Full Text Available The paper deals with the influence of diffractive optical elements on the optical aberrations. The correction of optical aberrations was investigated in the simple optical systems with one and two lenses (singlet and doublet. The advantages of diffractive optical elements are their ability to generate arbitrary complex wave fronts from a piece of optical material that is essentially flat. The optical systems consisting of the standard surfaces were designed and optimized by using the same starting points. Further, the diffractive and aspheric surfaces were introduced into the developed systems. The resulting hybrid systems were optimized. To compare the complicity of the development of narrow field systems and wide field optical systems, the optimization has been done separately for these two types of the instruments. The optical systems were designed by using special Optical Design Software. Тhe characteristics of designed diffractive surfaces were controlled in Software DIFSYS 2.30. Due to the application of diffractive optical elements the longitudinal chromatic aberration was 5 times reduced for the narrow field systems. The absolute value of Seidel coefficient related to the spherical aberration was reduced in the range of 0.03. Considering that diffractive optical elements have the known disadvantages, like possible parasitic diffraction orders and probable decrease of the transmission, we also developed and analyzed the optical systems with combined aspheric and diffractive surfaces. A combination of the aspheric and diffractive surfaces in the optical disk system of the disk reading lens, gave cutting down of the longitudinal color aberrations almost 15 times on-axis, comparing to the lens consisting of the aspherical and standard surfaces. All of the designed diffractive optical elements possess the parameters within the fabrication limits.

  2. Spontaneous and artificial direct nanostructuring of solid surface by extreme ultraviolet laser with nanosecond pulses

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Štraus, Jaroslav; Frolov, Oleksandr; Prukner, Václav; Melich, Radek; Psota, Pavel

    2016-01-01

    Roč. 34, č. 1 (2016), s. 11-22 ISSN 0263-0346 Institutional support: RVO:61389021 Keywords : Extreme ultraviolet (XUV) interferometer * Aspheric interferometer mirrors * Multilayer reflection coating for 46.9 nm * Ar8+ laser application * XUV direct nanostructuring Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.420, year: 2016 http://dx.doi.org/10.1017/S0263034615000786

  3. Full 3-D OCT-based pseudophakic custom computer eye model

    Science.gov (United States)

    Sun, M.; Pérez-Merino, P.; Martinez-Enriquez, E.; Velasco-Ocana, M.; Marcos, S.

    2016-01-01

    We compared measured wave aberrations in pseudophakic eyes implanted with aspheric intraocular lenses (IOLs) with simulated aberrations from numerical ray tracing on customized computer eye models, built using quantitative 3-D OCT-based patient-specific ocular geometry. Experimental and simulated aberrations show high correlation (R = 0.93; poptical geometrical and surgically-related factors to image quality, and are an excellent tool for characterizing and improving cataract surgery. PMID:27231608

  4. Qualification of a Null Lens Using Image-Based Phase Retrieval

    Science.gov (United States)

    Bolcar, Matthew R.; Aronstein, David L.; Hill, Peter C.; Smith, J. Scott; Zielinski, Thomas P.

    2012-01-01

    In measuring the figure error of an aspheric optic using a null lens, the wavefront contribution from the null lens must be independently and accurately characterized in order to isolate the optical performance of the aspheric optic alone. Various techniques can be used to characterize such a null lens, including interferometry, profilometry and image-based methods. Only image-based methods, such as phase retrieval, can measure the null-lens wavefront in situ - in single-pass, and at the same conjugates and in the same alignment state in which the null lens will ultimately be used - with no additional optical components. Due to the intended purpose of a Dull lens (e.g., to null a large aspheric wavefront with a near-equal-but-opposite spherical wavefront), characterizing a null-lens wavefront presents several challenges to image-based phase retrieval: Large wavefront slopes and high-dynamic-range data decrease the capture range of phase-retrieval algorithms, increase the requirements on the fidelity of the forward model of the optical system, and make it difficult to extract diagnostic information (e.g., the system F/#) from the image data. In this paper, we present a study of these effects on phase-retrieval algorithms in the context of a null lens used in component development for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Approaches for mitigation are also discussed.

  5. Advanced surface ablation for presbyopia using the Nidek EC-5000 laser.

    Science.gov (United States)

    Cantú, Roberto; Rosales, Marco A; Tepichín, Eduardo; Curioca, Andrée; Montes, Victor; Bonilla, Julio

    2004-01-01

    To present 1 to 6-month follow-up results of laser in situ keratomileusis (LASIK) using multizone presbyopic advanced surface ablation (PASA) with a peripheral near zone. LASIK was performed on 28 eyes of 17 patients (10 men and 7 women; mean age 49.8 years with a range of 37 to 62 years). Eyes had primary or enhancement treatments with the Nidek EC-5000 excimer laser. Three techniques were used: 1) total transepithelial ablation, 2) surface ablation for far vision ametropia correction, and 3) concentric peripheral near zone presbyopia correction (technique developed by Dr. A. Telandro with a modified nomogram by Dr. R. Cantú for surface ablation). One surgeon (RC) performed all surgery. We present the preoperative and postoperative measurements for far and near uncorrected visual acuity, total high order aberrations, spherical aberration (Z-12), asphericity Q index, eccentricity corneal shape factor, and total coma and trefoil aberrations. Increases occurred in negative spherical aberration, negative asphericity index, and positive eccentricity corneal shape factor. Advanced surface ablation for presbyopia with a concentric peripheral near zone is a promising approach for surgical correction of presbyopia and potentially could be used with any advanced surface ablation procedure. Increases in negative spherical aberration and asphericity/ eccentricity indices seemed to increase the depth of focus of the eye, improving the near vision.

  6. Acylinder and freeform optical manufacturing

    Science.gov (United States)

    Fess, Edward; Wolfs, Frank; DeFisher, Scott; Ross, James

    2015-10-01

    Aspheric cylinders have the ability to improve optical performance over standard cylindrical surfaces. Over the last several years there has also been development into the application and functionality of utilizing freeform surfaces to improve optical performance. Freeforms have the ability to not only improve image quality over a greater field of view, but can open up the design space of an optical system making it more compact. Freeform geometries, much like aspheric cylinders, may not have an axis of rotation to spin the optic about during manufacturing. This leads to costly fabrication processes and custom metrology set ups, which may inhibit their use. Over the last several years, OptiPro Systems has developed and optimized our eSX grinding, UFF and USF polishing, UltraSurf metrology, and ProSurf software programming technologies to make the processing of these complex geometries much easier and deterministic. In this paper we will discuss the challenges associated with manufacturing complex shapes like aspheric cylinders as well as freeform geometries, and how several technologies working together can overcome them. The technologies focus on metrology feedback to a grinding and polishing machine that is controlled through an iterative computer aided manufacturing software system. We will also present examples of these hard to manufacture shapes with results.

  7. Athermal design and analysis of glass-plastic hybrid lens

    Science.gov (United States)

    Yang, Jian; Cen, Zhaofeng; Li, Xiaotong

    2018-01-01

    With the rapid development of security market, the glass-plastic hybrid lens has gradually become a choice for the special requirements like high imaging quality in a wide temperature range and low cost. The reduction of spherical aberration is achieved by using aspherical surface instead of increasing the number of lenses. Obviously, plastic aspherical lens plays a great role in the cost reduction. However, the hybrid lens has a priority issue, which is the large thermal coefficient of expansion of plastic, causing focus shift and seriously affecting the imaging quality, so the hybrid lens is highly sensitive to the change of temperature. To ensure the system operates normally in a wide temperature range, it is necessary to eliminate the influence of temperature on the hybrid lens system. A practical design method named the Athermal Material Map is summarized and verified by an athermal design example according to the design index. It includes the distribution of optical power and selection of glass or plastic. The design result shows that the optical system has excellent imaging quality at a wide temperature range from -20 ° to 70 °. The method of athermal design in this paper has generality which could apply to optical system with plastic aspherical surface.

  8. The study of optimization on process parameters of high-accuracy computerized numerical control polishing

    Science.gov (United States)

    Huang, Wei-Ren; Huang, Shih-Pu; Tsai, Tsung-Yueh; Lin, Yi-Jyun; Yu, Zong-Ru; Kuo, Ching-Hsiang; Hsu, Wei-Yao; Young, Hong-Tsu

    2017-09-01

    Spherical lenses lead to forming spherical aberration and reduced optical performance. Consequently, in practice optical system shall apply a combination of spherical lenses for aberration correction. Thus, the volume of the optical system increased. In modern optical systems, aspherical lenses have been widely used because of their high optical performance with less optical components. However, aspherical surfaces cannot be fabricated by traditional full aperture polishing process due to their varying curvature. Sub-aperture computer numerical control (CNC) polishing is adopted for aspherical surface fabrication in recent years. By using CNC polishing process, mid-spatial frequency (MSF) error is normally accompanied during this process. And the MSF surface texture of optics decreases the optical performance for high precision optical system, especially for short-wavelength applications. Based on a bonnet polishing CNC machine, this study focuses on the relationship between MSF surface texture and CNC polishing parameters, which include feed rate, head speed, track spacing and path direction. The power spectral density (PSD) analysis is used to judge the MSF level caused by those polishing parameters. The test results show that controlling the removal depth of single polishing path, through the feed rate, and without same direction polishing path for higher total removal depth can efficiently reduce the MSF error. To verify the optical polishing parameters, we divided a correction polishing process to several polishing runs with different direction polishing paths. Compare to one shot polishing run, multi-direction path polishing plan could produce better surface quality on the optics.

  9. Optical Analysis of an Ultra-High resolution Two-Mirror Soft X-Ray Microscope

    Science.gov (United States)

    Shealy, David L.; Wang, Cheng; Hoover, Richard B.

    1994-01-01

    This work has summarized for a Schwarzschild microscope some relationships between numerical aperture (NA), magnification, diameter of the primary mirror, radius of curvature of the secondary mirror, and the total length of the microscope. To achieve resolutions better than a spherical Schwarzschild microscope of 3.3 Lambda for a perfectly aligned and fabricated system. it is necessary to use aspherical surfaces to control higher-order aberrations. For an NA of 0.35, the aspherical Head microscope provides diffraction limited resolution of 1.4 Lambda where the aspherical surfaces differ from the best fit spherical surface by approximately 1 micrometer. However, the angle of incidence varies significantly over the primary and the secondary mirrors, which will require graded multilayer coatings to operate near peak reflectivities. For higher numerical apertures, the variation of the angle of incidence over the secondary mirror surface becomes a serious problem which must be solved before multilayer coatings can be used for this application. Tolerance analysis of the spherical Schwarzschild microscope has shown that water window operations will require 2-3 times tighter tolerances to achieve a similar performance for operations with 130 A radiation. Surface contour errors have been shown to have a significant impact on the MTF and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror.

  10. Visual and Refractive Outcomes after Cataract Surgery with Implantation of a New Toric Intraocular Lens

    Directory of Open Access Journals (Sweden)

    Cinzia Mazzini

    2013-06-01

    Full Text Available Purpose: The aim of this study was to evaluate and report the visual, refractive and aberrometric outcomes of cataract surgery with implantation of the new aspheric Tecnis ZCT toric intraocular lens (IOL in eyes with low to moderate corneal astigmatism. Methods: We conducted a prospective study of 19 consecutive eyes of 17 patients (mean age: 78 years with a visually significant cataract and moderate corneal astigmatism [higher than 1 diopter (D] undergoing cataract surgery with implantation of the aspheric Tecnis ZCT toric IOL (Abbott Medical Optics. Visual, refractive and aberrometric changes were evaluated during a 6-month follow-up. Ocular aberrations as well as IOL rotation were evaluated by means of the OPD-Station II (Nidek. Results: The six-month postoperative spherical equivalent and power vector components of the refractive cylinder were within ±0.50 D in all eyes (100%. Postoperative logMAR uncorrected and corrected distance visual acuities (UDVA/CDVA were 0.1 (about 20/25 or better in almost all eyes (94.74%. The mean logMAR CDVA improved significantly from 0.41 ± 0.23 to 0.02 ± 0.05 (p Conclusion: Cataract surgery with implantation of the aspheric Tecnis ZCT IOL is a predictable and effective procedure for visual rehabilitation in eyes with cataract and low to moderate corneal astigmatism, providing an excellent postoperative ocular optical quality.

  11. Effect of static deformation and external forces on the oscillations of levitated droplets

    Science.gov (United States)

    Suryanarayana, P. V. R.; Bayazitoglu, Y.

    1991-01-01

    The oscillations of an aspherical droplet subjected to different external forces are considered. For an arbitrary shape deformation, it is shown that the frequency spectrum splits into (2l - 1) peaks for a mode l oscillation, and the splitting of the frequency spectrum is calculated for mode 2, 3, and 4 oscillations. The deformation is then treated as a consequence of a general external force, and the frequency split is obtained in terms of the external force parameters. Droplets levitated by acoustic, electromagnetic, and combined acoustic-electromagnetic forces are considered in particular, and it is shown that the effects of asphericity adequately explain the splitting of the frequency spectrum observed commonly in experiments. The interpretation of spectra with regard to accurate surface tension measurement using the oscillations of levitated droplets is discussed, and the results applied to some previous experimental results. It is shown that the accuracy of surface tension measurements can improve if the asphericity caused by the levitating force, and the resulting frequency split, are taken into account.

  12. Comparison of Anti-Reflective Coated and Uncoated Surfaces Figured by Pitch-Polishing and Magneto-Rheological Processes

    International Nuclear Information System (INIS)

    Chow, R.; Thomas, M.D.; Bickel, R.; Taylor, J.R.

    2002-01-01

    When completed, the National Ignition Facility (NIF) will provide laser energies in the Mega-joule range. Successful pulse amplification to these extremely high levels requires that all small optics, found earlier in the beamline, have stringent surface and laser fluence requirements. In addition, they must operate reliably for 30 years constituting hundreds of thousands of shots. As part of the first four beamlines, spherical and aspherical lenses were required for the beam relaying telescopes. The magneto-rheological technique allows for faster and more accurate finishing of aspheres. The spherical and aspherical lenses were final figured using both conventional-pitch polishing processes for high quality laser optics and the magneto-rheological finishing process. The purpose of this paper is to compare the surface properties between these two finishing processes. Some lenses were set aside from production for evaluation. The surface roughness in the mid-frequency range was measured and the scatter was studied. Laser damage testing at 1064 nm (3-ns pulse width) was performed on surfaces in both the uncoated and coated condition.

  13. Avaliação da sensibilidade ao contraste e da estereopsia em pacientes com lente intra-ocular multifocal Contrast sensitivity and stereopsis in pseudophakic patients with multifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Filipe de Oliveira

    2005-08-01

    Full Text Available OBJETIVO: Avaliar a sensibilidade ao contraste e a acuidade estereoscópica em pacientes pseudofácicos, que receberam implante bilateral de lente intra-ocular multifocal. MÉTODOS: Prospectivamente foram realizados testes de sensibilidade ao contraste com o uso da tabela Pelli-Robson e teste de acuidade estereoscópica com emprego do Titmus Stereo Test, em 20 pacientes com implante bilateral de lente intra-ocular multifocal Acrysof Restor®, no pós-operatório de 1 a 2 meses e sem uso de qualquer correção óptica. RESULTADOS:O teste de sensibilidade ao contraste binocular demonstrou que 6 pacientes (30% apresentaram 1,80 unid. log, 13 (65% 1,65 e 1 (5% 1,50. No teste monocular, ocorreram as seguintes respostas: 17 pacientes (85% 1,65 unid. log e 3 (15% 1,50 para o teste do olho direito. O teste do olho esquerdo mostrou que 16 pacientes (80% apresentaram 1,65 unid. log e 4 (20% 1,50. A média e o desvio-padrão da sensibilidade ao contraste testada binocularmente foi 1,69 (±0,08, ao passo que monocularmente foi 1,63 (±0,05 para OD e 1,62 (±0,06 para OE. O teste de acuidade estereoscópica revelou que 12 pacientes (60% obtiveram 40", 6 (30% 50" e 2 (10% 60", com média de 45" e desvio-padrão de ±6,88". CONCLUSÃO: A lente intra-ocular empregada no estudo, proporcionou resultados de sensibilidade ao contraste e acuidade estereoscópica compatíveis e de acordo com critérios de normalidade estabelecidos anteriormente por outros estudos em grupos de pacientes fácicos e pseudofácicos, e portanto, impacto positivo na funcionalidade visual.PURPOSE: To evaluate the contrast sensitivity and stereopsis tests in patients who underwent bilateral implantation of multifocal intraocular lens. METHODS: Tests of contrast sensitivity using the Pelli-Robson chart and stereopsis evaluation with the Titmus Stereo Test were performed in 20 patients 30-60 days after the bilateral implantation of Acrysof Restor® multifocal intraocular lens. RESULTS: The

  14. Influence of blue light spectrum filter on short-wavelength and standard automated perimetries Influência de filtro para o espectro azul da luz na perimetria computadorizada branco-branco e azul-amarelo

    Directory of Open Access Journals (Sweden)

    Leonardo Cunha Castro

    2006-10-01

    Full Text Available PURPOSE: To evaluate the influence of a blue light spectrum filter (BLSF, similar in light spectrum transmittance to the intraocular lens Acrysof NaturalTM, on standard automated perimetry (SAP and short-wavelength automated perimetry (SWAP. METHODS: Twenty young individuals (OBJETIVO: Avaliar a influência de um filtro para o espectro azul da luz, semelhante à lente intra-ocular Acrysof Natural®, nos exames de perimetria automatizada padrão (branco-no-branco e de comprimento de onda curto (azul-no-amarelo. MÉTODOS: Vinte pacientes jovens sem alterações oculares (20 olhos realizaram seqüência de 4 exames de campo visual: perimetria automatizada padrão e azul-no-amarelo com e sem o filtro para o espectro azul da luz. Os índices de limiar foveal (FT, desvio médio (MD e desvio-padrão (PSD obtidos em todos os exames e a diferença causada pela excentricidade nos exames de perimetria automatizada azul-no-amarelo foram analisados. Variabilidade interindivíduos (desvio-padrão dos pontos testados foi calculada. RESULTADOS: Observou-se redução estatisticamente significante no desvio médio (p<0.001 e no limiar foveal (p<0.001 medidos pela perimetria automatizada azul-no-amarelo com o uso do filtro para o espectro azul da luz comparado quando realizado sem o filtro. Nenhum outro índice avaliado apresentou diferença estatisticamente significante nos exames de perimetria automatizada padrão ou azul-no-amarelo. Foi notado aumento da variabilidade interindivíduos com a excentricidade nos exames de perimetria automatizada azul-no-amarelo com e sem o uso do filtro para o espectro azul da luz, assim como a diferença de sensibilidade entre os hemisférios inferior e superior (hemisfério inferior menos superior, mas não houve diferença estatisticamente significante quando comparados os exames com e sem o uso do filtro. Quando foram comparados os 4 pontos mais inferiores e os 4 pontos mais superiores, a diferença inferior-superior aumentou

  15. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract

    Directory of Open Access Journals (Sweden)

    Asim Kumar Kandar

    2014-01-01

    Full Text Available We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9 after fixation of lens capsule with Cionni′s capsular tension ring (CTR for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK. He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°. At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni′s ring with toric IOL could be a good option to manage such complex cases.

  16. Modelling lifetime cost consequences of toric compared with standard IOLs in cataract surgery of astigmatic patients in four European countries.

    Science.gov (United States)

    Laurendeau, C; Lafuma, A; Berdeaux, G

    2009-09-01

    To compare the lifetime costs of freeing astigmatic patients from spectacles after bilateral cataract surgery implanting toric intraocular lenses (IOLs: i.e., Acrysof Toric) versus monofocal IOLs, in France, Italy, Germany and Spain. A Markov model followed patient cohorts from cataract surgery until death. Prevalence rates of patients not needing spectacles and the types of spectacles prescribed for those requiring them were obtained from clinical trials and national surveys. The economic perspective was societal. Mortality rates were incorporated into the model. Discount rates were applied. A sensitivity analysis was performed on non-discounted costs. Fewer patients with toric IOLs needed spectacles for distance vision than patients with monofocal IOLs. With monofocal IOLs more than 66% of patients needed complex spectacles compared to less than 25% implanted with toric IOLs. In France and Italy, toric IOLs reduced overall costs relative to otherwise high spectacle costs after cataract surgery. Savings were 897.0 euros (France), 822.5 euros (Germany), 895.8 euros (Italy) and 391.6 euros (Spain), without discounting. On applying a 3% discount rate the costs became 691.7 euros, 646.4 euros, 693.9 euros and 308.2 euros, respectively. Bilateral toric IOL implants in astigmatic patients decreased spectacle dependence for distance vision and the need for complex spectacles. The economic consequences for patients depended on the national spectacle costs usually incurred after cataract surgery.

  17. Alpins and thibos vectorial astigmatism analyses: proposal of a linear regression model between methods

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2013-10-01

    Full Text Available PURPOSE: To determine linear regression models between Alpins descriptive indices and Thibos astigmatic power vectors (APV, assessing the validity and strength of such correlations. METHODS: This case series prospectively assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted among two phacoemulsification groups: one assigned to receive AcrySof®Toric intraocular lens (IOL in both eyes and another assigned to have AcrySof Natural IOL associated with limbal relaxing incisions, also in both eyes. All patients were reevaluated postoperatively at 6 months, when refractive astigmatism analysis was performed using both Alpins and Thibos methods. The ratio between Thibos postoperative APV and preoperative APV (APVratio and its linear regression to Alpins percentage of success of astigmatic surgery, percentage of astigmatism corrected and percentage of astigmatism reduction at the intended axis were assessed. RESULTS: Significant negative correlation between the ratio of post- and preoperative Thibos APVratio and Alpins percentage of success (%Success was found (Spearman's ρ=-0.93; linear regression is given by the following equation: %Success = (-APVratio + 1.00x100. CONCLUSION: The linear regression we found between APVratio and %Success permits a validated mathematical inference concerning the overall success of astigmatic surgery.

  18. Comparison between OPD-Scan results and visual outcomes of monofocal and multifocal intraocular lenses Comparação dos resultados do OPD-Scan e performance visual das lentes intraoculares monofocal e multifocal

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2009-08-01

    Full Text Available PURPOSE: To compare the visual outcome, contrast sensitivity and wavefront analysis of patients that underwent cataract surgery and implantation of AcrySof SN60D3 multifocal intraocular lens with those who received the AcrySof SN60AT monofocal IOL. METHODS: This was a prospective clinical trial of forty eyes that received the multifocal IOL and thirty-two eyes that received the monofocal IOL after phacoemulsification. RESULTS: Values for total and spherical aberrations in the multifocal group were statistically lower than in the monofocal group. In the monofocal group, 75% achieved uncorrected intermediate visual acuities between Jaeger 1 and 6. In the multifocal group, 75% of the eyes achieved more than Jaeger 6. At least 87.5% of the multifocal group and 6.3% of the monofocal group achieved monocular uncorrected near acuity of 20/30 (J2, N5 or better. And 90.0% of the eyes in the multifocal group and 37.5% in the monofocal group achieved an uncorrected near acuity of 20/40 (J3, N6 or better. The mean spherical error was 0.11 D in the multifocal group and -0.18 D in the monofocal group (p=0.0379. The SN60D3 group compared to SN60AT group had low contrast sensitivity (log units with statistically significant differences in 6.0 cpd in photopic conditions (p=0.014 and the SN60D3 group compared to SN60AT group had higher contrast sensitivity (log units under mesopic conditions (p=0.044. CONCLUSION: The multifocal IOLs induced less spherical aberration than monofocal IOLs and predictably good uncorrected distance and uncorrected near acuities. However, contrast sensitivity was lower in the multifocal group.OBJETIVO: Comparar a performance visual, sensibilidade ao contraste e de wavefront com OPD-Scan em pacientes submetidos a cirurgia de facoemulsificação com implante de lente intraocular AcrySof SN60D3 multifocal e AcrySof SA60AT monofocal. MÉTODOS: Quarenta olhos com a lente intraocular multifocal e trinta e dois olhos com a lente intraocular

  19. Delayed diagnosis of homocystinuria presenting as bilateral congenital lens subluxation

    Directory of Open Access Journals (Sweden)

    Jelić-Vuković Marija

    2017-01-01

    Full Text Available Introduction. Homocystinuria is an autosomal recessively inherited defect leading to hyperhomocysteinemia and associated with ocular manifestations, mainly myopia and ectopia lentis. Case outline. A 26-year-old male with secondary glaucoma due to bilateral lens subluxation was admitted to the Department of vitreoretinal surgery. Horizontal nystagmus, bilateral lens subluxation, and bilateral amblyopia were first discovered at the age of three years. Preoperative laboratory workup revealed elevated levels of homocysteine. Bilateral pars plana lensectomy and vitrectomy followed by a sulcus fixation of the intraocular lens (ALCON MA60 Acrysof IOL were performed. The patient was prescribed folic acid, methionine, and pyridoxine, and was urged to maintain a methionine-low diet. After a bilateral lensectomy and sulcus fixation of the intraocular lens and a methionine restriction therapy combined with vitamin B6, B9, and B12 supplementation, his condition improved greatly. Conclusion. In this report of a rare case we emphasize the importance of examining differential diagnoses of lens subluxation, since early intervention can prevent serious complications.

  20. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract.

    Science.gov (United States)

    Kandar, Asim Kumar

    2014-07-01

    We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9) after fixation of lens capsule with Cionni's capsular tension ring (CTR) for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK). He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°). At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni's ring with toric IOL could be a good option to manage such complex cases.

  1. Inverse optical design and its applications

    Science.gov (United States)

    Sakamoto, Julia Angela

    We present a new method for determining the complete set of patient-specific ocular parameters, including surface curvatures, asphericities, refractive indices, tilts, decentrations, thicknesses, and index gradients. The data consist of the raw detector outputs of one or more Shack-Hartmann wavefront sensors (WFSs); unlike conventional wavefront sensing, we do not perform centroid estimation, wavefront reconstruction, or wavefront correction. Parameters in the eye model are estimated by maximizing the likelihood. Since a purely Gaussian noise model is used to emulate electronic noise, maximum-likelihood (ML) estimation reduces to nonlinear least-squares fitting between the data and the output of our optical design program. Bounds on the estimate variances are computed with the Fisher information matrix (FIM) for different configurations of the data-acquisition system, thus enabling system optimization. A global search algorithm called simulated annealing (SA) is used for the estimation step, due to multiple local extrema in the likelihood surface. The ML approach to parameter estimation is very time-consuming, so rapid processing techniques are implemented with the graphics processing unit (GPU). We are leveraging our general method of reverse-engineering optical systems in optical shop testing for various applications. For surface profilometry of aspheres, which involves the estimation of high-order aspheric coefficients, we generated a rapid raytracing algorithm that is well-suited to the GPU architecture. Additionally, reconstruction of the index distribution of GRIN lenses is performed using analytic solutions to the eikonal equation. Another application is parameterized wavefront estimation, in which the pupil phase distribution of an optical system is estimated from multiple irradiance patterns near focus. The speed and accuracy of the forward computations are emphasized, and our approach has been refined to handle large wavefront aberrations and nuisance

  2. Four corneal presbyopia corrections: simulations of optical consequences on retinal image quality.

    Science.gov (United States)

    Koller, Tobias; Seiler, Theo

    2006-12-01

    To investigate the possibility of multifocal or aspherical treatment of the cornea with optical ray tracing. Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland. The optical consequences of 4 corneal shapes-global optimum (GO) for curvature and asphericity, central steep island (CSI), decentered steep island (DSI), and centered steep annulus (CSA)-for presbyopia correction were analyzed using a modified Liou-Brennan eye model and ray tracing with a commercial optic design software (Zemax, Zemax Development Corp.). The ocular optical configuration for far vision was a point light source at a distance of 5 m, 1 degree up, and a pupil diameter of 5.0 mm and for near vision, 0.4 m distance, 1 degree up, and a pupil diameter of 2.5 mm. The curvature radius (R) of the cornea and its asphericity (Q) were used as operands to optimize (simultaneously for near and far vision) the quality of the retinal image described by means of the minimum spot diameter or the root-mean-square (RMS) wavefront error. Starting from an emmetropic eye optimized for R and Q, the RMS wavefront error in the retina was 0.07 microm (far) and 1.42 microm (near). The GO resulted in a wavefront error of 1.42 microm (far) and 0.52 microm (near); improvement of near vision using reading glasses is possible. The CSI yielded 0.91 microm (far) and 0.13 microm (near); spectacles did not improve far or near vision. The DSI and CSA had significantly worse results for near and far vision. Of the options studied, GO and CSI seemed the most promising alternatives for corneal presbyopia correction. Although reading glasses can improve near vision in GO, reading glasses did not improve near vision in CSI-treated eyes. The CSI treatment is critically dependent on centration and a reverse treatment is difficult to achieve.

  3. Electronic, magnetic, and magnetocrystalline anisotropy properties of light lanthanides

    Science.gov (United States)

    Hackett, Timothy A.; Baldwin, D. J.; Paudyal, D.

    2017-11-01

    Theoretical understanding of interactions between localized and mobile electrons and the crystal environment in light lanthanides is important because of their key role in much needed magnetic anisotropy in permanent magnet materials that have a great impact in automobile and wind turbine applications. We report electronic, magnetic, and magnetocrystalline properties of these basic light lanthanide elements studied from advanced density functional theory (DFT) calculations. We find that the inclusion of onsite 4f electron correlation and spin orbit coupling within the full-potential band structure is needed to understand the unique magnetocrystalline properties of these light lanthanides. The onsite electron correlation, spin orbit coupling, and full potential for the asphericity of charge densities must be taken into account for the proper treatment of 4f states. We find the variation of total energy as a function of lattice constants that indicate multiple structural phases in Ce contrasting to a single stable structure obtained in other light lanthanides. The 4f orbital magnetic moments are partially quenched as a result of crystalline electric field splitting that leads to magnetocrystalline anisotropy. The charge density plots have similar asphericity and environment in Pr and Nd indicating similar magnetic anisotropy. However, Ce and Sm show completely different asphericity and environment as both orbital moments are significantly quenched. In addition, the Fermi surface structures exemplified in Nd indicate structural stability and unravel a cause of anisotropy. The calculated magnetocrystalline anisotropy energy (MAE) reveals competing c-axis and in-plane anisotropies, and also predicts possibilities of unusual structural deformations in light lanthanides. The uniaxial magnetic anisotropy is obtained in the double hexagonal closed pack structures of the most of the light lanthanides, however, the anisotropy is reduced or turned to planar in the low symmetry

  4. Effect of Coating Parameters of the Buffer Layer on the Shape Ratio of TRISO-Coated Particles

    International Nuclear Information System (INIS)

    KIm, Weon Ju; Park, Jong Hoon; Park, Ji Yeon; Lee, Young Woo; Chang, Jong Hwa

    2005-01-01

    Fuel for high temperature gas-cooled reactors (HTGR's) consists of TRISO-coated particles. Fluidized bed chemical vapor deposition (FBCVD) has been applied to fabricate the TRISO-coated fuel particles. The TRISO particles consist of UO 2 microspheres coated with layers of porous pyrolytic carbon (PyC), inner dense PyC (IPyC), SiC, and outer dense PyC (OPyC). The porous PyC coating layer, called the buffer layer, attenuates fission recoils and provides void volume for gaseous fission products and carbon monoxide. The buffer layer, which has the highest coating rate among the coating layers, shows the largest variation of the coating thickness within a particle and a batch. This could be the most plausible source of an asphericity in the TRISO particles. The aspherical particles are expected to have an inferior fuel performance. Miller et al. have predicted that a larger stress is developed within the coating layers and thus the failure probability increases in the particles with high aspect ratios. Therefore, the shape of the TRISO-coated particles should be controlled properly and has been one of the important inspection items for the quality control of the fabrication process. In this paper, we investigated the effect of coating parameters of the buffer layer on the shape of the TRISO particles. The flow rate of coating gas and the coating temperature were varied to control the buffer layer. The asphericity of the TRISO-coated particles was evaluated for the various coating conditions of the buffer layer, but at constant coating parameters for the IPyC/SiC/OPyC layers

  5. Image Science Research for Speckle-based LADAR (Speckle Research for 3D Imaging LADAR)

    Science.gov (United States)

    2008-04-03

    INVARIANT + FERGUS, TORRALBA, AND FREEMAN. MIT-CSAIL-TR-2006-058 MAP DETECTOR PATTERN FOR EACH POINT IN OBJECT SPACE DEBLURRING PROBLEM IMPULSE RESPONSE...GENERALIZED THEORY FOR THE LOGARITHMIC ASPHERE ( )( ) it e φ ρρ −= IMPULSE RESPONSE (PSF) 2 2 2 2 0 0 22 2( ) 2 2 0 2 2 2 2 2 2 0 0 2 ( ; ) 2 ( ) i s i i t R...ascent; γ=1, Burch, Skilling, Gull; Loops needed Noise deviation Area of PSF New parameter L σ A γ COMPARISON OF MAXIMUM ENTROPY METHODS † † W. CHI

  6. Phase measuring deflectometry. An improved setup for measuring CTA mirror facets

    Energy Technology Data Exchange (ETDEWEB)

    Specovius, Andreas; Eldik, Christopher van; Woernlein, Andre; Ziegler, Alexander [Erlangen Centre for Astroparticle Physics (ECAP) (Germany)

    2016-07-01

    The future Cherenkov Telescope Array (CTA) will consist of up to 100 single telescopes with a total reflecting surface of ∝10.000 m{sup 2} made of numerous mirror facets. Characterizing the surface properties of these facets is quite challenging concerning time and logistics. An efficient way to reliably reconstruct the surface of specular free-forms is Phase Measuring Deflectometry (PMD). PMD is routinely used to characterize the focal distance and point spread function of spherical CTA prototype mirrors. To address the possibility to measure the surface properties of aspherical mirrors, a new PMD setup has recently been built. First experience with this setup is reported.

  7. Note: optical optimization for ultrasensitive photon mapping with submolecular resolution by scanning tunneling microscope induced luminescence.

    Science.gov (United States)

    Chen, L G; Zhang, C; Zhang, R; Zhang, X L; Dong, Z C

    2013-06-01

    We report the development of a custom scanning tunneling microscope equipped with photon collection and detection systems. The optical optimization includes the comprehensive design of aspherical lens for light collimation and condensing, the sophisticated piezo stages for in situ lens adjustment inside ultrahigh vacuum, and the fiber-free coupling of collected photons directly onto the ultrasensitive single-photon detectors. We also demonstrate submolecular photon mapping for the molecular islands of porphyrin on Ag(111) under small tunneling currents down to 10 pA and short exposure time down to 1.2 ms/pixel. A high quantum efficiency up to 10(-2) was also observed.

  8. Method for selecting hollow microspheres for use in laser fusion targets

    Science.gov (United States)

    Farnum, Eugene H.; Fries, R. Jay; Havenhill, Jerry W.; Smith, Maurice Lee; Stoltz, Daniel L.

    1976-01-01

    Hollow microspheres having thin and very uniform wall thickness are useful as containers for the deuterium and tritium gas mixture used as a fuel in laser fusion targets. Hollow microspheres are commercially available; however, in commercial lots only a very small number meet the rigid requirements for use in laser fusion targets. Those meeting these requirements may be separated from the unsuitable ones by subjecting the commercial lot to size and density separations and then by subjecting those hollow microspheres thus separated to an external pressurization at which those which are aspherical or which have nonuniform walls are broken and separating the sound hollow microspheres from the broken ones.

  9. Exact optics - III. Schwarzschild's spectrograph camera revised

    Science.gov (United States)

    Willstrop, R. V.

    2004-03-01

    Karl Schwarzschild identified a system of two mirrors, each defined by conic sections, free of third-order spherical aberration, coma and astigmatism, and with a flat focal surface. He considered it impractical, because the field was too restricted. This system was rediscovered as a quadratic approximation to one of Lynden-Bell's `exact optics' designs which have wider fields. Thus the `exact optics' version has a moderate but useful field, with excellent definition, suitable for a spectrograph camera. The mirrors are strongly aspheric in both the Schwarzschild design and the exact optics version.

  10. High-precision photometry by telescope defocusing - VII. The ultrashort period planet WASP-103

    DEFF Research Database (Denmark)

    Southworth, John; Mancini, L.; Ciceri, S.

    2015-01-01

    for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP......-103. Our data were obtained in the Bessell $RI$ and the SDSS $griz$ passbands and yield a larger planet radius at bluer optical wavelengths, to a confidence level of 7.3 sigma. Interpreting this as an effect of Rayleigh scattering in the planetary atmosphere leads to a measurement of the planetary...

  11. Horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications.

    Science.gov (United States)

    Ma, Hongcai; Wu, Lin

    2015-07-10

    We present the design of a horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications. This solar concentrator consists of an array of telecentric primary concentrators, a horizontally staggered lightguide layer, and a vertically tapered lightguide layer. The primary concentrator is realized by two plano-aspheric lenses with lateral movement and maintains a high F-number over an angle range of ±23.5°. The results of the simulations show that the solar concentrator achieves a high concentration ratio of 500× with ±0.5° of acceptance angle by a single-axis tracker and dual lateral translation stages.

  12. Reflective and refractive optical materials for earth and space applications; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1991

    Science.gov (United States)

    Riedl, Max J.; Hale, Robert R.; Parsonage, Thomas B.

    The present conference discusses beryllium mirror design and fabrication, production of aspheric beryllium optical surfaces by HIP consolidation, the control of thermally induced porosity for the fabrication of beryllium optics, fine-grained beryllium optical coatings, light-absorbing beryllium baffle materials, and advanced broadband baffle materials. Also discussed are radiation-resistant optical glasses, a catalog of IR and cryooptical properties of selected materials, durable metal-dielectric mirror coatings, the optical stability of diffuse reflectance materials, and optical filters for space applications.

  13. Enhanced resolution and accuracy of freeform metrology through Subaperture Stitching Interferometry

    Science.gov (United States)

    Supranowitz, Chris; Maloney, Chris; Murphy, Paul; Dumas, Paul

    2017-10-01

    Recent advances in polishing and metrology have addressed many of the challenges in the fabrication and metrology of freeform surfaces, and the manufacture of these surfaces is possible today. However, achieving the form and mid-spatial frequency (MSF) specifications that are typical of visible imaging systems remains a challenge. Interferometric metrology for freeform surfaces is thus highly desirable for such applications, but the capability is currently quite limited for freeforms. In this paper, we provide preliminary results that demonstrate accurate, high-resolution measurements of freeform surfaces using prototype software on QED's ASI™ (Aspheric Stitching Interferometer).

  14. Endothelial cell loss and refractive predictability in femtosecond laser-assisted cataract surgery compared with conventional cataract surgery

    DEFF Research Database (Denmark)

    Krarup, Therese; Holm, Lars Morten; la Cour, Morten

    2014-01-01

    and the contralateral eye operated by CPS (stop and chop technique). Both eyes had intraocular aspheric lenses implanted. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), central corneal endothelial cell count and hexagonality with a non-contact specular microscope were assessed......PURPOSE: To investigate the amount of endothelial cell loss (ECL) and refractive predictability by femtosecond laser-assisted cataract surgery (FLACS) compared to conventional phacoemulsification cataract surgery (CPS). METHODS: Forty-seven patients had one eye operated by FLACS...

  15. A UV prime focus spectrograph for the CFHT

    International Nuclear Information System (INIS)

    Boulade, O.; Vigroux, L.

    1986-03-01

    The UV prime spectrograph at the Canada-France-Hawaii Telescope is the first instrument to be designed with an aspherized diffraction grating. This technique leads to all reflective Schmidt designs with a very small amount of optical surface on fast aperture ratio. A thin backside illuminated RCA CCD is now used as the detector. Since the detector is at the focus of an f/1 mounting, within the optical path, a minicryostat (5 cm x 5 cm x 3 cm) was designed to minimize the central obscuration. This paper describes this new instrument and its performances

  16. Frontal view reconstruction for iris recognition

    Science.gov (United States)

    Santos-Villalobos, Hector J; Bolme, David S; Boehnen, Chris Bensing

    2015-02-17

    Iris recognition can be accomplished for a wide variety of eye images by correcting input images with an off-angle gaze. A variety of techniques, from limbus modeling, corneal refraction modeling, optical flows, and genetic algorithms can be used. A variety of techniques, including aspherical eye modeling, corneal refraction modeling, ray tracing, and the like can be employed. Precomputed transforms can enhance performance for use in commercial applications. With application of the technologies, images with significantly unfavorable gaze angles can be successfully recognized.

  17. simEye: computer-based simulation of visual perception under various eye defects using Zernike polynomials

    OpenAIRE

    Fink, Wolfgang; Micol, Daniel

    2006-01-01

    We describe a computer eye model that allows for aspheric surfaces and a three-dimensional computer-based ray-tracing technique to simulate optical properties of the human eye and visual perception under various eye defects. Eye surfaces, such as the cornea, eye lens, and retina, are modeled or approximated by a set of Zernike polynomials that are fitted to input data for the respective surfaces. A ray-tracing procedure propagates light rays using Snell’s law of refraction from an input objec...

  18. Magnetic and magnetoelastic properties of the random anisotropy amorphous magnets Tb2(FexNi1-x)

    International Nuclear Information System (INIS)

    De la Fuente, C.; Arnaudas, J.I.; Del Moral, A.; Ciria, M.

    1996-01-01

    Amorphous Tb 2 (Fe x Ni 1-x ) compounds show the strongest random anisotropy known: D/J≅5.2, between crystal field and exchange strengths, separately obtained. The magnetic phase diagram shows two speri-magnetic phases. The effective magnetic moment is reduced, μ eff. (5 K, 12 T)≅7.2 μ B /Tb 3+ . Magnetostriction is very large and constant, λ t (5 K, 12 T)≅4.1.10 -3 . The local distribution of Tb 3+ ions is aspherical. (orig.)

  19. Topology of high-dimensional manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, F T [State University of New York, Binghamton (United States); Goettshe, L [Abdus Salam ICTP, Trieste (Italy); Lueck, W [Westfaelische Wilhelms-Universitaet Muenster, Muenster (Germany)

    2002-08-15

    The School on High-Dimensional Manifold Topology took place at the Abdus Salam ICTP, Trieste from 21 May 2001 to 8 June 2001. The focus of the school was on the classification of manifolds and related aspects of K-theory, geometry, and operator theory. The topics covered included: surgery theory, algebraic K- and L-theory, controlled topology, homology manifolds, exotic aspherical manifolds, homeomorphism and diffeomorphism groups, and scalar curvature. The school consisted of 2 weeks of lecture courses and one week of conference. Thwo-part lecture notes volume contains the notes of most of the lecture courses.

  20. Flat dielectric metasurface lens array for three dimensional integral imaging

    Science.gov (United States)

    Zhang, Jianlei; Wang, Xiaorui; Yang, Yi; Yuan, Ying; Wu, Xiongxiong

    2018-05-01

    In conventional integral imaging, the singlet refractive lens array limits the imaging performance due to its prominent aberrations. Different from the refractive lens array relying on phase modulation via phase change accumulated along the optical paths, metasurfaces composed of nano-scatters can produce phase abrupt over the scale of wavelength. In this letter, we propose a novel lens array consisting of two neighboring flat dielectric metasurfaces for integral imaging system. The aspherical phase profiles of the metasurfaces are optimized to improve imaging performance. The simulation results show that our designed 5 × 5 metasurface-based lens array exhibits high image quality at designed wavelength 865 nm.

  1. Strong coupling between a single nitrogen-vacancy spin and the rotational mode of diamonds levitating in an ion trap

    Science.gov (United States)

    Delord, T.; Nicolas, L.; Chassagneux, Y.; Hétet, G.

    2017-12-01

    A scheme for strong coupling between a single atomic spin and the rotational mode of levitating nanoparticles is proposed. The idea is based on spin readout of nitrogen-vacancy centers embedded in aspherical nanodiamonds levitating in an ion trap. We show that the asymmetry of the diamond induces a rotational confinement in the ion trap. Using a weak homogeneous magnetic field and a strong microwave driving we then demonstrate that the spin of the nitrogen-vacancy center can be strongly coupled to the rotational mode of the diamond.

  2. Customized computer models of eyes with intraocular lenses.

    Science.gov (United States)

    Rosales, P; Marcos, S

    2007-03-05

    We compared experimental wave aberrations in pseudophakic eyes with aspheric intraocular lenses (IOLs) to simulate aberrations from numerical ray tracing on customized computer eye models using corneal topography, angle lambda, ocular biometry, IOL geometry, and IOL tilt and decentration measured on the same eyes. We found high correlations between real and simulated aberrations even for the eye with only the cornea, and these increased on average when the IOL geometry and position were included. Relevant individual aberrations were well predicted by the complete eye model. Corneal spherical aberration and horizontal coma were compensated by the IOL, and in 58.3% of the cases IOL tilt and decentration contributed to compensation of horizontal coma. We conclude that customized computer eye models are a good representation of real eyes with IOLs and allow understanding of the relative contribution of optical, geometrical and surgically-related factors to image quality. Corneal spherical aberration is reduced by aspheric IOLs, although other corneal high order aberrations are still a major contributor to total aberrations in pseudophakic eyes. Tilt and decentration of the IOLs represent a relatively minor contribution of the overall optical quality of the eye.

  3. Optical cylinder designs to increase the field of vision in the osteo-odonto-keratoprosthesis.

    Science.gov (United States)

    Hull, C C; Liu, C S; Sciscio, A; Eleftheriadis, H; Herold, J

    2000-12-01

    The single optical cylinders used in the osteo-odonto-keratoprosthesis (OOKP) are known to produce very small visual fields. Values of 40 degrees are typically quoted. The purpose of this paper is to present designs for new optical cylinders that significantly increase the field of view and therefore improve the visual rehabilitation of patients having an OOKP. Computer ray-tracing techniques were used to design and analyse improved one- and two-piece optical cylinders made from polymethyl methacrylate. All designs were required to have a potential visual acuity of 6/6 before consideration was given to the visual field and optimising off-axis image quality. Aspheric surfaces were used where this significantly improved off-axis image quality. Single optical cylinders, with increased posterior cylinder (intraocular) diameters, gave an increase in the theoretical visual field of 18% (from 76 degrees to 90 degrees) over current designs. Two-piece designs based on an inverted telephoto principle gave theoretical field angles over 120 degrees. Aspheric surfaces were shown to improve the off-axis image quality while maintaining a potential visual acuity of at least 6/6. This may well increase the measured visual field by improving the retinal illuminance off-axis. Results demonstrate that it is possible to significantly increase the theoretical maximum visual field through OOKP optical cylinders. Such designs will improve the visual rehabilitation of patients undergoing this procedure.

  4. Computer Generated Hologram System for Wavefront Measurement System Calibration

    Science.gov (United States)

    Olczak, Gene

    2011-01-01

    Computer Generated Holograms (CGHs) have been used for some time to calibrate interferometers that require nulling optics. A typical scenario is the testing of aspheric surfaces with an interferometer placed near the paraxial center of curvature. Existing CGH technology suffers from a reduced capacity to calibrate middle and high spatial frequencies. The root cause of this shortcoming is as follows: the CGH is not placed at an image conjugate of the asphere due to limitations imposed by the geometry of the test and the allowable size of the CGH. This innovation provides a calibration system where the imaging properties in calibration can be made comparable to the test configuration. Thus, if the test is designed to have good imaging properties, then middle and high spatial frequency errors in the test system can be well calibrated. The improved imaging properties are provided by a rudimentary auxiliary optic as part of the calibration system. The auxiliary optic is simple to characterize and align to the CGH. Use of the auxiliary optic also reduces the size of the CGH required for calibration and the density of the lines required for the CGH. The resulting CGH is less expensive than the existing technology and has reduced write error and alignment error sensitivities. This CGH system is suitable for any kind of calibration using an interferometer when high spatial resolution is required. It is especially well suited for tests that include segmented optical components or large apertures.

  5. Preliminary observation of refractive cataract surgery assisted by femtosecond laser

    Directory of Open Access Journals (Sweden)

    Xiao-Li Wang

    2015-12-01

    Full Text Available AIM:To compare the differences of visual acuity and corneal astigmatism postoperatively between conventional refractive cataract surgery and that assisted by femtosecond laser.METHODS:Sixty patients(60 eyeswith age-related cataract and cornea astigmatism were divided into femtosecond group and conventional group randomly or voluntarily. The flat shaft, steep shaft and diopter of corneal astigmatism in patients in femtosecond group were inputted into the online vector calculators to get the location and width of the incision. Then femtosecond laser was used to make corneal releasing incision, the main and auxiliary incision. Phacoemulsification and aspheric multifocal intraocular lens implantation were undergone. Patients in conventional group received full-thickness relaxing incision by cornea paracentesis knife at the steepest meridian axis during phacoemulsification. Then aspheric multifocal intraocular lenses were implanted. Uncorrected distance visual acuity(UCDVA, uncorrected near visual acuity(UCNVAand cornea astigmatism were observed at 1d,1wk and 1mo postoperative. RESULTS:UCVA of patients in both groups was improved after the surgeries. UCDVA and UCNVA of femtosecond group were higher than those of conventional group, while the cornea astigmatism of femtosecond group was lower than that of conventional group.CONCLUSION:Refractile cataract surgery assisted by femtosecond laser canoffer better visual quality than conventional refractive cataract surgery because of lower cornea astigmatism and better visual acuity.

  6. Assembly and alignment method for optimized spatial resolution of off-axis three-mirror fore optics of hyperspectral imager.

    Science.gov (United States)

    Kim, Youngsoo; Hong, Jinsuk; Choi, Byungin; Lee, Jong-Ung; Kim, Yeonsoo; Kim, Hyunsook

    2017-08-21

    A fore optics for the hyperspectral spectrometer is designed, manufactured, assembled, and aligned. The optics has a telecentric off-axis three-mirror configuration with a field of view wider than 14 degrees and an f-number as small as 2.3. The primary mirror (M1) and the secondary mirror (M2) are axially symmetric aspheric surfaces to minimize the sensitivity. The tertiary mirror (M3) is a decentered aspheric surface to minimize the coma and astigmatism aberration. The M2 also has a hole for the slit to maintain the optical performance while maximizing the telecentricity. To ensure the spatial resolution performance of the optical system, an alignment procedure is established to assemble and align the entrance slit of the spectrometer to the rear end of the fore optics. It has a great advantage to confirm and maintain the alignment integrity of the fore optics module throughout the alignment procedure. To perform the alignment procedure successfully, the precision movement control requirements are calculated and applied. As a result, the alignment goal of the RMS wave front error (WFE) to be smaller than 90 nm at all fields is achieved.

  7. Chromatic confocal microscopy for multi-depth imaging of epithelial tissue

    Science.gov (United States)

    Olsovsky, Cory; Shelton, Ryan; Carrasco-Zevallos, Oscar; Applegate, Brian E.; Maitland, Kristen C.

    2013-01-01

    We present a novel chromatic confocal microscope capable of volumetric reflectance imaging of microstructure in non-transparent tissue. Our design takes advantage of the chromatic aberration of aspheric lenses that are otherwise well corrected. Strong chromatic aberration, generated by multiple aspheres, longitudinally disperses supercontinuum light onto the sample. The backscattered light detected with a spectrometer is therefore wavelength encoded and each spectrum corresponds to a line image. This approach obviates the need for traditional axial mechanical scanning techniques that are difficult to implement for endoscopy and susceptible to motion artifact. A wavelength range of 590-775 nm yielded a >150 µm imaging depth with ~3 µm axial resolution. The system was further demonstrated by capturing volumetric images of buccal mucosa. We believe these represent the first microstructural images in non-transparent biological tissue using chromatic confocal microscopy that exhibit long imaging depth while maintaining acceptable resolution for resolving cell morphology. Miniaturization of this optical system could bring enhanced speed and accuracy to endomicroscopic in vivo volumetric imaging of epithelial tissue. PMID:23667789

  8. New high-precision deep concave optical surface manufacturing capability

    Science.gov (United States)

    Piché, François; Maloney, Chris; VanKerkhove, Steve; Supranowicz, Chris; Dumas, Paul; Donohue, Keith

    2017-10-01

    This paper describes the manufacturing steps necessary to manufacture hemispherical concave aspheric mirrors for high- NA systems. The process chain is considered from generation to final figuring and includes metrology testing during the various manufacturing steps. Corning Incorporated has developed this process by taking advantage of recent advances in commercially available Satisloh and QED Technologies equipment. Results are presented on a 100 mm concave radius nearly hemispherical (NA = 0.94) fused silica sphere with a better than 5 nm RMS figure. Part interferometric metrology was obtained on a QED stitching interferometer. Final figure was made possible by the implementation of a high-NA rotational MRF mode recently developed by QED Technologies which is used at Corning Incorporated for production. We also present results from a 75 mm concave radius (NA = 0.88) Corning ULE sphere that was produced using sub-aperture tools from generation to final figuring. This part demonstrates the production chain from blank to finished optics for high-NA concave asphere.

  9. Multiconjugate adaptive optics applied to an anatomically accurate human eye model.

    Science.gov (United States)

    Bedggood, P A; Ashman, R; Smith, G; Metha, A B

    2006-09-04

    Aberrations of both astronomical telescopes and the human eye can be successfully corrected with conventional adaptive optics. This produces diffraction-limited imagery over a limited field of view called the isoplanatic patch. A new technique, known as multiconjugate adaptive optics, has been developed recently in astronomy to increase the size of this patch. The key is to model atmospheric turbulence as several flat, discrete layers. A human eye, however, has several curved, aspheric surfaces and a gradient index lens, complicating the task of correcting aberrations over a wide field of view. Here we utilize a computer model to determine the degree to which this technology may be applied to generate high resolution, wide-field retinal images, and discuss the considerations necessary for optimal use with the eye. The Liou and Brennan schematic eye simulates the aspheric surfaces and gradient index lens of real human eyes. We show that the size of the isoplanatic patch of the human eye is significantly increased through multiconjugate adaptive optics.

  10. A study on ultra-precision machining technique for Al6061-T6 to fabricate space infrared optics

    Science.gov (United States)

    Ryu, Geun-man; Lee, Gil-jae; Hyun, Sang-won; Sung, Ha-yeong; Chung, Euisik; Kim, Geon-hee

    2014-08-01

    In this paper, analysis of variance on designed experiments with full factorial design was applied to determine the optimized machining parameters for ultra-precision fabrication of the secondary aspheric mirror, which is one of the key elements of the space cryogenic infrared optics. A single point diamond turning machine (SPDTM, Nanotech 4μpL Moore) was adopted to fabricate the material, AL6061-T6, and the three machining parameters of cutting speed, feed rate and depth of cut were selected. With several randomly assigned experimental conditions, surface roughness of each condition was measured by a non-contact optical profiler (NT2000; Vecco). As a result of analysis using Minitab, the optimum cutting condition was determined as following; cutting speed: 122 m/min, feed rate: 3 mm/min and depth of cut: 1 μm. Finally, a 120 mm diameter aspheric secondary mirror was attached to a particularly designed jig by using mixture of paraffin and wax and successfully fabricated under the optimum machining parameters. The profile of machined surface was measured by a high-accuracy 3-D profilometer(UA3P; Panasonic) and we obtained the geometrical errors of 30.6 nm(RMS) and 262.4 nm(PV), which satisfy the requirements of the space cryogenic infrared optics.

  11. Hydrogen-Poor Core-Collapse Supernovae

    Science.gov (United States)

    Pian, Elena; Mazzali, Paolo A.

    Hydrogen-poor core-collapse supernovae (SNe) signal the explosive death of stars more massive than the progenitors of hydrogen-rich core-collapse supernovae, i.e., approximately in the range 15-50 M⊙ in main sequence. Since hydrogen-poor core-collapse supernovae include those that accompany gamma-ray bursts (GRBs), which were all rigorously identified with type Ic supernovae, their explosion energies cover almost two decades. The light curves and spectra are consequently very heterogeneous and often bear the signature of an asymmetric, i.e., aspherical, explosion. Asphericity is best traced by early-time (within days of the explosion) optical spectropolarimetry and by late-epoch (more than ˜ 100 days after explosion) low-resolution spectroscopy. While the relationship between hydrogen-poor core-collapse supernovae to hydrogen-poor super-luminous supernovae is not understood, a known case of association between an ultra-long gamma-ray burst and a very luminous hydrogen-poor supernova may help unraveling the connection. This is tantalizingly pointing to a magnetar powering source for both phenomena, although this scenario is still highly speculative. Host galaxies of hydrogen-poor supernovae are always star forming; in those of completely stripped supernovae and gamma-ray burst supernovae, the spatial distribution of the explosions follows the blue/ultraviolet light, with a correlation that is more than linear.

  12. Wavefront measurement of plastic lenses for mobile-phone applications

    Science.gov (United States)

    Huang, Li-Ting; Cheng, Yuan-Chieh; Wang, Chung-Yen; Wang, Pei-Jen

    2016-08-01

    In camera lenses for mobile-phone applications, all lens elements have been designed with aspheric surfaces because of the requirements in minimal total track length of the lenses. Due to the diffraction-limited optics design with precision assembly procedures, element inspection and lens performance measurement have become cumbersome in the production of mobile-phone cameras. Recently, wavefront measurements based on Shack-Hartmann sensors have been successfully implemented on injection-molded plastic lens with aspheric surfaces. However, the applications of wavefront measurement on small-sized plastic lenses have yet to be studied both theoretically and experimentally. In this paper, both an in-house-built and a commercial wavefront measurement system configured on two optics structures have been investigated with measurement of wavefront aberrations on two lens elements from a mobile-phone camera. First, the wet-cell method has been employed for verifications of aberrations due to residual birefringence in an injection-molded lens. Then, two lens elements of a mobile-phone camera with large positive and negative power have been measured with aberrations expressed in Zernike polynomial to illustrate the effectiveness in wavefront measurement for troubleshooting defects in optical performance.

  13. Multiconjugate adaptive optics applied to an anatomically accurate human eye model

    Science.gov (United States)

    Bedggood, P. A.; Ashman, R.; Smith, G.; Metha, A. B.

    2006-09-01

    Aberrations of both astronomical telescopes and the human eye can be successfully corrected with conventional adaptive optics. This produces diffraction-limited imagery over a limited field of view called the isoplanatic patch. A new technique, known as multiconjugate adaptive optics, has been developed recently in astronomy to increase the size of this patch. The key is to model atmospheric turbulence as several flat, discrete layers. A human eye, however, has several curved, aspheric surfaces and a gradient index lens, complicating the task of correcting aberrations over a wide field of view. Here we utilize a computer model to determine the degree to which this technology may be applied to generate high resolution, wide-field retinal images, and discuss the considerations necessary for optimal use with the eye. The Liou and Brennan schematic eye simulates the aspheric surfaces and gradient index lens of real human eyes. We show that the size of the isoplanatic patch of the human eye is significantly increased through multiconjugate adaptive optics.

  14. Mirrors design, analysis and manufacturing of the 550mm Korsch telescope experimental model

    Science.gov (United States)

    Huang, Po-Hsuan; Huang, Yi-Kai; Ling, Jer

    2017-08-01

    In 2015, NSPO (National Space Organization) began to develop the sub-meter resolution optical remote sensing instrument of the next generation optical remote sensing satellite which follow-on to FORMOSAT-5. Upgraded from the Ritchey-Chrétien Cassegrain telescope optical system of FORMOSAT-5, the experimental optical system of the advanced optical remote sensing instrument was enhanced to an off-axis Korsch telescope optical system which consists of five mirrors. It contains: (1) M1: 550mm diameter aperture primary mirror, (2) M2: secondary mirror, (3) M3: off-axis tertiary mirror, (4) FM1 and FM2: two folding flat mirrors, for purpose of limiting the overall volume, reducing the mass, and providing a long focal length and excellent optical performance. By the end of 2015, we implemented several important techniques including optical system design, opto-mechanical design, FEM and multi-physics analysis and optimization system in order to do a preliminary study and begin to develop and design these large-size lightweight aspheric mirrors and flat mirrors. The lightweight mirror design and opto-mechanical interface design were completed in August 2016. We then manufactured and polished these experimental model mirrors in Taiwan; all five mirrors ware completed as spherical surfaces by the end of 2016. Aspheric figuring, assembling tests and optical alignment verification of these mirrors will be done with a Korsch telescope experimental structure model in 2018.

  15. Hydrogen ADPs with Cu Kα data? Invariom and Hirshfeld atom modelling of fluconazole.

    Science.gov (United States)

    Orben, Claudia M; Dittrich, Birger

    2014-06-01

    For the structure of fluconazole [systematic name: 2-(2,4-difluorophenyl)-1,3-bis(1H-1,2,4-triazol-1-yl)propan-2-ol] monohydrate, C13H12F2N6O·H2O, a case study on different model refinements is reported, based on single-crystal X-ray diffraction data measured at 100 K with Cu Kα radiation to a resolution of sin θ/λ of 0.6 Å(-1). The structure, anisotropic displacement parameters (ADPs) and figures of merit from the independent atom model are compared to `invariom' and `Hirshfeld atom' refinements. Changing from a spherical to an aspherical atom model lowers the figures of merit and improves both the accuracy and the precision of the geometrical parameters. Differences between results from the two aspherical-atom refinements are small. However, a refinement of ADPs for H atoms is only possible with the Hirshfeld atom density model. It gives meaningful results even at a resolution of 0.6 Å(-1), but requires good low-order data.

  16. Research and development project in fiscal 1990 for large industrial technologies. Achievement report on research and development of ultra-advanced processing systems (Development of high-level processing devices for electric power generation facility members); 1990 nendo chosentan kako system no kenkyu kaihatsu seika hokokusho. Hatsuden shisetsuyo buzai kodo kako sochi kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-03-01

    Research and development has been performed with an objective to establish the processing technology using excitation beam required for the advanced technology industries, and the ultra-precision machining technology to realize the nano-technology. This paper summarizes the achievements in fiscal 1990. In the research on the large output and long life technology for excimer laser, an average output of 500 W or more was demonstrated achieving the intermediate target by developing and improving the technologies for low electric power gas circulation, high efficiency discharge and excitation, and large output oscillation control. In the research on intensity resistant optical element technology, a prototype device was fabricated to create and process axially symmetrical aspherical shapes, whereas SiC aspherical shape creation and processing were demonstrated at the shape accuracy of three microns or better, and surface roughness of 20 nanometers or less, having achieved the intermediate target. Regarding the large current ion beam, a demonstration device was completed based on improvements and test results on the sheet plasma generator. In the research and development of the high-level processing technology, low-temperature forming technology was developed for oxide ceramic thin films by using the excimer laser abrasion method. (NEDO)

  17. Normalization and Implementation of Three Gravitational Acceleration Models

    Science.gov (United States)

    Eckman, Randy A.; Brown, Aaron J.; Adamo, Daniel R.; Gottlieb, Robert G.

    2016-01-01

    Unlike the uniform density spherical shell approximations of Newton, the consequence of spaceflight in the real universe is that gravitational fields are sensitive to the asphericity of their generating central bodies. The gravitational potential of an aspherical central body is typically resolved using spherical harmonic approximations. However, attempting to directly calculate the spherical harmonic approximations results in at least two singularities that must be removed to generalize the method and solve for any possible orbit, including polar orbits. Samuel Pines, Bill Lear, and Robert Gottlieb developed three unique algorithms to eliminate these singularities. This paper documents the methodical normalization of two of the three known formulations for singularity-free gravitational acceleration (namely, the Lear and Gottlieb algorithms) and formulates a general method for defining normalization parameters used to generate normalized Legendre polynomials and Associated Legendre Functions (ALFs) for any algorithm. A treatment of the conventional formulation of the gravitational potential and acceleration is also provided, in addition to a brief overview of the philosophical differences between the three known singularity-free algorithms.

  18. Correction of low corneal astigmatism in cataract surgery.

    Science.gov (United States)

    Leon, Pia; Pastore, Marco Rocco; Zanei, Andrea; Umari, Ingrid; Messai, Meriem; Negro, Corrado; Tognetto, Daniele

    2015-01-01

    To evaluate and compare aspheric toric intraocular lens (IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions (LRI) to manage low corneal astigmatism (1.0-2.0 D) in cataract surgery. A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes (102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were: visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III (Nidek Co, Japan). Follow-up lasted 6mo. The mean uncorrected distance visual acuity (UCVA) and the best corrected visual acuity (BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group (P<0.01). No difference was observed in the postoperative endothelial cell count between the two groups. The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

  19. Experimental verification of the minimum number of diffractive zones for effective chromatic correction in the LWIR

    Science.gov (United States)

    Ramsey, J. L.; Walsh, K. F.; Smith, M.; Deegan, J.

    2016-05-01

    With the move to smaller pixel sizes in the longwave IR region there has been a push for shorter focal length lenses that are smaller, cheaper and lighter and that resolve lower spatial frequencies. As a result lenses must have better correction for both chromatic and monochromatic aberrations. This leads to the increased use of aspheres and diffractive optical elements (kinoforms). With recent developments in the molding of chalcogenide materials these aspheres and kinoforms are more cost effective to manufacture. Without kinoforms the axial color can be on the order of 15 μm which degrades the performance of the lens at the Nyquist frequency. The kinoforms are now on smaller elements and are correcting chromatic aberration which is on the order of the design wavelength. This leads to kinoform structures that do not require large phase changes and therefore have 1.5 to just over 2 zones. The question becomes how many zones are required to correct small amounts of chromatic aberration in the system and are they functioning as predicted by the lens design software? We investigate both the design performance and the as-built performance of two designs that incorporate kinoforms for the correction of axial chromatic aberration.

  20. An analytical method for predicting the geometrical and optical properties of the human lens under accommodation.

    Science.gov (United States)

    Sheil, Conor J; Bahrami, Mehdi; Goncharov, Alexander V

    2014-05-01

    We present an analytical method to describe the accommodative changes in the human crystalline lens. The method is based on the geometry-invariant lens model, in which the gradient-index (GRIN) iso-indicial contours are coupled to the external shape. This feature ensures that any given number of iso-indicial contours does not change with accommodation, which preserves the optical integrity of the GRIN structure. The coupling also enables us to define the GRIN structure if the radii and asphericities of the external lens surfaces are known. As an example, the accommodative changes in lenticular radii and central thickness were taken from the literature, while the asphericities of the external surfaces were derived analytically by adhering to the basic physical conditions of constant lens volume and its axial position. The resulting changes in lens geometry are consistent with experimental data, and the optical properties are in line with expected values for optical power and spherical aberration. The aim of the paper is to provide an anatomically and optically accurate lens model that is valid for 3 mm pupils and can be used as a new tool for better understanding of accommodation.

  1. On the temperature dependence of H-U{sub iso} in the riding hydrogen model

    Energy Technology Data Exchange (ETDEWEB)

    Lübben, Jens; Volkmann, Christian [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Grabowsky, Simon [School of Chemistry and Biochemistry, Stirling Highway 35, WA-6009 Crawley (Australia); Edwards, Alison [Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Morgenroth, Wolfgang [Institut für Geowissenschaften, Abteilung Kristallographie, Goethe-Universität, Altenhöferallee 1, 60438 Frankfurt am Main (Germany); Fabbiani, Francesca P. A. [GZG, Abteilung Kristallographie, Georg-August Universität, Goldschmidtstrasse 1, 37077 Göttingen (Germany); Sheldrick, George M. [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Dittrich, Birger, E-mail: birger.dittrich@chemie.uni-hamburg.de [Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany)

    2014-07-01

    The temperature dependence of hydrogen U{sub iso} and parent U{sub eq} in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U{sub iso} in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U{sub iso} below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found.

  2. On the temperature dependence of H-Uiso in the riding hydrogen model

    International Nuclear Information System (INIS)

    Lübben, Jens; Volkmann, Christian; Grabowsky, Simon; Edwards, Alison; Morgenroth, Wolfgang; Fabbiani, Francesca P. A.; Sheldrick, George M.; Dittrich, Birger

    2014-01-01

    The temperature dependence of hydrogen U iso and parent U eq in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U iso in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U iso below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found

  3. Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

    Science.gov (United States)

    Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

    2013-12-01

    We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

  4. Design of an omnidirectional single-point photodetector for large-scale spatial coordinate measurement

    Science.gov (United States)

    Xie, Hongbo; Mao, Chensheng; Ren, Yongjie; Zhu, Jigui; Wang, Chao; Yang, Lei

    2017-10-01

    In high precision and large-scale coordinate measurement, one commonly used approach to determine the coordinate of a target point is utilizing the spatial trigonometric relationships between multiple laser transmitter stations and the target point. A light receiving device at the target point is the key element in large-scale coordinate measurement systems. To ensure high-resolution and highly sensitive spatial coordinate measurement, a high-performance and miniaturized omnidirectional single-point photodetector (OSPD) is greatly desired. We report one design of OSPD using an aspheric lens, which achieves an enhanced reception angle of -5 deg to 45 deg in vertical and 360 deg in horizontal. As the heart of our OSPD, the aspheric lens is designed in a geometric model and optimized by LightTools Software, which enables the reflection of a wide-angle incident light beam into the single-point photodiode. The performance of home-made OSPD is characterized with working distances from 1 to 13 m and further analyzed utilizing developed a geometric model. The experimental and analytic results verify that our device is highly suitable for large-scale coordinate metrology. The developed device also holds great potential in various applications such as omnidirectional vision sensor, indoor global positioning system, and optical wireless communication systems.

  5. Effect of cataract surgery on retinal nerve fiber layer thickness parameters using scanning laser polarimetry (GDxVCC).

    Science.gov (United States)

    Dada, Tanuj; Behera, Geeta; Agarwal, Anand; Kumar, Sanjeev; Sihota, Ramanjit; Panda, Anita

    2010-01-01

    To study the effect of cataract extraction on the retinal nerve fiber layer (RNFL) thickness, and assessment by scanning laser polarimetry (SLP), with variable corneal compensation (GDx VCC), at the glaucoma service of a tertiary care center in North India. Thirty-two eyes of 32 subjects were enrolled in the study. The subjects underwent RNFL analysis by SLP (GDx VCC) before undergoing phacoemulsification cataract extraction with intraocular lens (IOL) implantation (Acrysof SA 60 AT) four weeks following cataract surgery. The RNFL thickness parameters evaluated both before and after surgery included temporal, superior, nasal, inferior, temporal (TSNIT) average, superior average, inferior average, and nerve fiber index (NFI). The mean age of subjects was 57.6 +/- 11.7 years (18 males, 14 females). Mean TSNIT average thickness (microm) pre- and post-cataract surgery was 49.2 +/- 14.1 and 56.5 +/- 7.6 ( P = 0.001). There was a statistically significant increase in RNFL thickness parameters (TSNIT average, superior average, and inferior average) and decrease in NFI post-cataract surgery as compared to the baseline values. Mean NFI pre- and post-cataract surgery was 41.3 +/- 15.3 and 21.6 +/- 11.8 ( P = 0.001). Measurement of RNFL thickness parameters by scanning laser polarimetry is significantly altered following cataract surgery. Post the cataract surgery, a new baseline needs to be established for assessing the longitudinal follow-up of a glaucoma patient. The presence of cataract may lead to an underestimation of the RNFL thickness, and this should be taken into account when analyzing progression in a glaucoma patient.

  6. Correlating optical bench performance with clinical defocus curves in varifocal and trifocal intraocular lenses.

    Science.gov (United States)

    Plaza-Puche, Ana B; Alió, Jorge L; MacRae, Scott; Zheleznyak, Len; Sala, Esperanza; Yoon, Geunyoung

    2015-05-01

    To investigate the correlations existing between a trifocal intraocular lens (IOL) and a varifocal IOL using the "ex vivo" optical bench through-focus image quality analysis and the clinical visual performance in real patients by study of the defocus curves. This prospective, consecutive, nonrandomized, comparative study included a total of 64 eyes of 42 patients. Three groups of eyes were differentiated according to the IOL implanted: 22 eyes implanted with the varifocal Lentis Mplus LS-313 IOL (Oculentis GmbH, Berlin, Germany); 22 eyes implanted with the trifocal FineVision IOL (Physiol, Liege, Belgium), and 20 eyes implanted with the monofocal Acrysof SA60AT IOL (Alcon Laboratories, Inc., Fort Worth, TX). Visual outcomes and defocus curve were evaluated postoperatively. Optical bench through-focus performance was quantified by computing an image quality metric and the cross-correlation coefficient between an unaberrated reference image and captured retinal images from a model eye with a 3.0-mm artificial pupil. Statistically significant differences among defocus curves of different IOLs were detected for the levels of defocus from -4.00 to -1.00 diopters (D) (P < .01). Significant correlations were found between the optical bench image quality metric results and logMAR visual acuity scale in all groups (Lentis Mplus group: r = -0.97, P < .01; FineVision group: r = -0.82, P < .01; Acrys of group: r = -0.99, P < .01). Linear predicting models were obtained. Significant correlations were found between logMAR visual acuity and image quality metric for the multifocal and monofocal IOLs analyzed. This finding enables surgeons to predict visual outcomes from the optical bench analysis. Copyright 2015, SLACK Incorporated.

  7. Torsional ultrasound mode versus combined torsional and conventional ultrasound mode phacoemulsification for eyes with hard cataract.

    Science.gov (United States)

    Fakhry, Mohamed A; El Shazly, Malak I

    2011-01-01

    To compare torsional versus combined torsional and conventional ultrasound modes in hard cataract surgery regarding ultrasound energy and time and effect on corneal endothelium. Kasr El Aini hospital, Cairo University, and International Eye Hospital, Cairo, Egypt. Ninety-eight eyes of 63 patients were enrolled in this prospective comparative randomized masked clinical study. All eyes had nuclear cataracts of grades III and IV using the Lens Opacities Classification System III (LOCS III). Two groups were included, each having an equal number of eyes (49). The treatment for group A was combined torsional and conventional US mode phacoemulsification, and for group B torsional US mode phacoemulsification only. Pre- and post-operative assessments included best corrected visual acuity (BCVA), intraocular pressure (IOP), slit-lamp evaluation, and fundoscopic evaluation. Endothelial cell density (ECD) and central corneal thickness (CCT) were measured preoperatively, 1 day, 7 days, and 1 month postoperatively. All eyes were operated on using the Alcon Infiniti System (Alcon, Fort Worth, TX) with the quick chop technique. All eyes were implanted with AcrySof SA60AT (Alcon) intraocular lens (IOL). The main phaco outcome parameters included the mean ultrasound time (UST), the mean cumulative dissipated energy (CDE), and the percent of average torsional amplitude in position 3 (%TUSiP3). Improvement in BCVA was statistically significant in both groups (P < 0.001). Comparing UST and CDE for both groups revealed results favoring the pure torsional group (P = 0.002 and P < 0.001 for UST; P = 0.058 and P = 0.009 for CDE). As for %TUSiP3, readings were higher for the pure torsional group (P = 0.03 and P = 0.01). All changes of CCT, and ECD over time were found statistically significant using one-way ANOVA testing (P < 0.001). Both modes are safe in hard cataract surgery, however the pure torsional mode showed less US energy used.

  8. Toric Intraocular Lens Outcomes in Patients With Glaucoma.

    Science.gov (United States)

    Brown, Reay H; Zhong, Le; Bozeman, Caroline W; Lynch, Mary G

    2015-06-01

    To report the outcomes of toric intraocular lens implantation in patients with glaucoma and corneal astigmatism. One hundred twenty-six eyes of 87 patients with glaucoma and corneal astigmatism that underwent cataract surgery with an AcrySof toric intraocular lens (Alcon Laboratories, Inc., Fort Worth, TX) implant were selected for this single-center, retrospective case series. Corrected distance visual acuity, intraocular pressure, and refractive astigmatism were measured in each eye preoperatively and postoperatively. Uncorrected distance visual acuity and toric alignment were measured postoperatively. The uncorrected distance visual acuity was 0.04 ± 0.08 logMAR (20/22 Snellen) for all eyes. Ninety-eight percent of all eyes achieved an uncorrected distance visual acuity of 20/40 or better, with 76% achieving 20/25 or better and 47% achieving 20/20. The corrected distance visual acuity for all eyes was 0.01 ± 0.03 logMAR (20/20.5 Snellen) postoperatively. The refractive cylinder improved from 1.47 ± 1.10 diopters preoperatively to 0.31 ± 0.37 diopters postoperatively. The residual refractive cylinder was 1.00 diopter or less in 97% of eyes, 0.75 diopters or less in 90% of eyes, and 0.50 diopters or less in 83% of eyes. Mean misalignment was 4.4° ± 5.1°. Intraocular pressure decreased by a mean of 2.3 ± 3.3 mm Hg following the surgery. Toric intraocular lenses can reliably reduce astigmatism and improve uncorrected vision in eyes with cataract and glaucoma. Copyright 2015, SLACK Incorporated.

  9. Image-guided system versus manual marking for toric intraocular lens alignment in cataract surgery.

    Science.gov (United States)

    Webers, Valentijn S C; Bauer, Noel J C; Visser, Nienke; Berendschot, Tos T J M; van den Biggelaar, Frank J H M; Nuijts, Rudy M M A

    2017-06-01

    To compare the accuracy of toric intraocular lens (IOL) alignment using the Verion Image-Guided System versus a conventional manual ink-marking procedure. University Eye Clinic Maastricht, Maastricht, the Netherlands. Prospective randomized clinical trial. Eyes with regular corneal astigmatism of at least 1.25 diopters (D) that required cataract surgery and toric IOL implantation (Acrysof SN6AT3-T9) were randomly assigned to the image-guided group or the manual-marking group. The primary outcome was the alignment of the toric IOL based on preoperative images and images taken immediately after surgery. Secondary outcome measures were residual astigmatism, uncorrected distance visual acuity (UDVA), and complications. The study enrolled 36 eyes (24 patients). The mean toric IOL misalignment was significantly less in the image-guided group than in the manual group 1 hour (1.3 degrees ± 1.6 [SD] versus 2.8 ± 1.8 degrees; P = .02) and 3 months (1.7 ± 1.5 degrees versus 3.1 ± 2.1 degrees; P image-guided group and manual group, respectively (P > .05). The mean UDVA was 0.03 ± 0.10 logarithm of minimum angle of resolution (logMAR) and 0.04 ± 0.09 logMAR, respectively (both P > .05). No intraoperative complications occurred during any surgery. The IOL misalignment was significantly less with digital marking than with manual marking; this did not result in a better UDVA or lower residual refractive astigmatism. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  10. Diagnóstico e tratamento do lenticone anterior

    Directory of Open Access Journals (Sweden)

    Ana Luiza Biancardi

    2011-08-01

    Full Text Available Relato de caso de um paciente de 18 anos com sindrome de Alport apresentando perda visual progressiva. A biomicroscopia revelou lenticone anterior bilateral. O paciente realizou tomografia de córnea e segmento anterior com o sistema Scheimpflug (Pentacam e aberrometria e topografia corneana (i-Trace. O paciente foi submetido à facoemulsificação com implante de lente intraocular peça única hidrofóbica (Acrysof® SN60AT. As imagens de Scheimpflug documentaram o lenticone anterior. A aberrometria total mostrou acentuado astigmatismo miópico com acentuada aberração esférica negativa, havendo grande impacto das aberrações de alta ordem (HOA na conversão da letra E de Snellen. O mapa de integração da aberrometria do olho todo com a topografia corneana mostrou maior semelhança das aberrrações totais com as aberrações intraoculares do que com as aberrações da superfície anterior da córnea. Após a cirurgia, o paciente apresentou acuidade visual corrigida igual a 20/20 em ambos os olhos, as imagens de Scheimpflug revelaram lentes intraoculares tópicas e os mapas diferenciais revelaram resolução da miopia e redução das aberrações da alta ordem (total e interna. Os exames de imagem foram úteis para demonstrar o impacto do lenticone anterior na qualidade visual e a resolução das aberrações ópticas após a cirurgia.

  11. Cionni ring and in-the-bag intraocular lens implantation for subluxated lenses: a prospective case series.

    Science.gov (United States)

    Vasavada, Abhay R; Praveen, Mamidipudi R; Vasavada, Viraj A; Yeh, Ru-Yin; Srivastava, Samaresh; Koul, Archana; Trivedi, Rupal H

    2012-06-01

    To report the intraoperative performance and postoperative outcomes of the Cionni-modified capsule tension ring (CTR) implantation in eyes with subluxated lenses. Prospective, observational case series. This study was carried out at Iladevi Cataract & IOL Research Centre, Ahmedabad, India. The study population comprised 41 eyes with subluxated lenses that underwent lens extraction, capsular bag fixation with modified CTR, and in-the-bag single-piece AcrySof intraocular lens (IOL) implantation. Main outcome measures were intraoperative performance and postoperative best-corrected visual acuity (BCVA), IOL centration, and complications. The mean age was 29.46 ± 16.16 years (3-68 years). Mean extent of subluxation was 6.1 ± 1.0 clock hours. Preoperatively, vitreous was detected in the anterior chambers of 5 eyes (12.2%). Two-port anterior chamber vitrectomy was performed in 2 eyes. Mean follow-up was 45.8 ± 2.9 months. Mean preoperative BCVA was 0.66 ± 0.22 logMAR (35 eyes). Mean postoperative BCVA at final follow-up was 0.33 ± 0.21 logMAR (41 eyes) (P IOL decentration was noted and repositioning was required in 2 eyes. Posterior capsule opacification developed in 14 eyes (34.2%); 12 eyes (29.3%) required Nd:YAG capsulotomy. Other complications included cystoid macular edema in 1 eye (2.4%), posterior synechiae in 1 eye (2.4%), and retinal detachment in 1 eye (2.4%). In-the-bag implantation of a Cionni-modified CTR with IOL appears to be a safe option in eyes with subluxated cataract, ensuring a stable IOL with few complications. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Outcomes of iris-claw anterior chamber versus iris-fixated foldable intraocular lens in subluxated lens secondary to Marfan syndrome.

    Science.gov (United States)

    Hirashima, Denise E; Soriano, Eduardo S; Meirelles, Rodrigo L; Alberti, Gustave N; Nosé, Walton

    2010-08-01

    To compare the outcome of phacoemulsification using 2 different iris-fixation techniques for intraocular lens (IOL) replacement, a foldable posterior chamber IOL (PCIOL; AcrySof MA60AC, Alcon Laboratories Inc, Fort Worth, TX) and an iris-claw anterior chamber IOL (ACIOL; Artisan, Ophtec BV), for treatment of subluxated lenses in patients with Marfan syndrome (MFS). Randomized, controlled trial. A total of 31 eyes of 16 patients with subluxated lenses associated with MFS and a preoperative corrected visual acuity (CVA) IOL type. Preoperative and postoperative ophthalmologic examination, optical coherence tomography, and endothelial cell counts were performed. We recorded CVA results at 3, 6, and 12 months, complications, endothelial cell loss, and central retinal thickness. In the iris-fixated PCIOL group, CVA was significantly improved at 3 (P = 0.011; n = 16), 6 (P = 0.006; n = 16), and 12 months (P = 0.002; n = 16). In the iris-claw ACIOL group, CVA was significantly improved at 3 (P = 0.001; n=15), 6 (P = 0.001; n = 15), and 12 months (P = 0.009; n = 12). The CVA results did not differ significantly between groups. Dislocation of the IOL occurred in 3 of 16 (18.75%) eyes in the PCIOL group. Retinal detachment occurred in 3 eyes (2 in the PCIOL group and 1 in the ACIOL group) and was successfully repaired. Postoperative foveal tomograms in both groups revealed a decrease in the mean foveal thickness (MFT; IOL dislocation tended to occur more frequently in the iris-fixated PCIOL group, the difference was not significant. At 6 months postoperatively, all study patients tended to have a thinner MFT. None of the patients in either group developed cystoid macular edema. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  13. [Iris hooks and modified capsular tension ring for subluxation lens in patients with Marfan's syndrome].

    Science.gov (United States)

    Wu, Wen-Jie; Zheng, Dan-ying; Zheng, Ying-feng; Cai, Xiao-yu

    2007-02-01

    To evaluate clinical efficiency and safety of the iris hooks and modified capsular tension ring (MCTR) for the treatment of subluxation lens in patients with Marfan's syndrome. This study comprised 5 patients (7 eyes) with Marfan's syndrome and subluxation lens. After 3.2 mm clear cornea incision and continuous curvilinear capsulorhexis (CCC), 2 - 4 disposable nylon iris hooks were inserted through the stab incisions and placed in the capsulorhexis to support the capsule and enlarged the CCC. Following irrigation/aspiration, a MCTR with suture in its eyelet was placed in the capsule bag. After tightening and tying the suture of MCTR, the capsular bag was centered and fixed. A foldable AcrySof one-piece intraocular lens (IOL) was then placed in the capsule bag. Twelve months after the operation, the best corrected visual acuity was >/= 0.8 in six eyes and 0.7 in one eye. The scheimpflug images obtained from the Pentacam demonstrated that the IOL were well centered. UBM showed that all the MCTR and the haptics of the IOL were in the capsule bag, the eyelet of the MCTR was rested stably between the capsulorhexis margin and the iris. The retroillumination photograph indicated that only one eye had obvious posterior capsular opacification. No intraoperative and postoperative complications such as prolapse of vitreous and retina detachment was occurred. The iris hooks can provide excellent intraoperative capsule-lens stability and facilitate the manipulation during operation. MCTR allows additional suture fixation to the eye wall without damaging the capsular bag and maintains the long-term stability of the intraocular lens. Furthermore, MCTR is helpful for avoiding dislocation of the IOL due to progressive weakening of the zonular fibers in some patients and provides long-term safety.

  14. Phakic Intraocular Lens Implantation: Refractive Outcome and Safety in Patients with Anterior Chamber Depth between 2.8 and 3.0 versus ≥3.0 mm.

    Science.gov (United States)

    Guerra, Marta G; Silva, Andreia M M; Marques, Sara H M; Melo, Sofia H; Póvoa, João A; Lobo, Conceição; Murta, Joaquim Neto

    2017-01-01

    To compare endothelial cell (EC) variation after anterior chamber phakic intraocular lens (AC-pIOL) implantation in highly myopic patients with a preoperative anterior chamber depth (ACD) between 2.8 and 3.0 versus ≥3.0 mm. A total of 280 eyes submitted to primary AC-pIOL implantation were analyzed. Pre- and postoperative values for uncorrected distance visual acuity, corrected distance visual acuity, spherical equivalent, ACD (endothelial surface), and EC count were collected. The eyes were divided into 2 groups: group A - ACD between 2.8 and 3.0 mm; group B - ACD ≥3.0 mm. Mean global EC loss (ECL) and loss for each ACD group, according to pIOL type, were analyzed. Significant improvement of the spherical equivalent (-11.38 ± 4.57 vs. -0.49 ± 0.79; p = 0.000) and a significant decrease in EC density (2,810.95 ± 343.88 vs. 2,584.09 ± 374.88 cells/mm2; p = 0.000) were noted. The mean annual ECL was -2.19 ± 3.97%. Regarding group A (n = 80), a mean annual ECL of -2.06 ± 3.88% was registered, higher for the Acrysof Cachet® subtype, while group B (n = 200) showed -2.25 ± 4.01% ECL, higher for the Verisyse® subtype. There was no significant difference between the groups (p = 0.96). AC-pIOL implantation significantly improves the spherical equivalent in myopic patients. The mean annual ECL after pIOL implantation was higher in the larger ACD group, but this value was not statistically significant. A 2.8-mm ACD value seems to be a safe cutoff for AC-pIOL implantation. © 2017 S. Karger AG, Basel.

  15. Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus

    Directory of Open Access Journals (Sweden)

    Mofty H

    2017-11-01

    Full Text Available Hanan Mofty,1,2 Khaled Alzahrani,2 Fiona Carley,3 Sophie Harper,3 Arun Brahma,3 Leon Au,3 Debbie Morley,3 M Chantal Hillarby2 1Optometry Department, College of Applied Medical Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3Manchester Royal Eye Hospital, Manchester, UK Purpose: The purpose of this study was to assess UV corneal crosslinking (CXL treatment outcomes for keratoconus by evaluating the corneal regularity in patients through follow-up using the Oculus Pentacam.Patients and methods: A total of 18 eyes from CXL patients with keratoconus were studied before and after CXL treatment, and six eyes from six patients who were not treated with CXL served as controls. Treated patients had Pentacam images taken before CXL treatment and regularly 3 months post treatment up to the 12th month. Controls were imaged during their first appointment and after 12 months. Symmetry and asphericity were evaluated and correlated with both best-corrected visual acuity (BCVA and maximum K-readings.Results: In the CXL-treated group, there was a significant improvement in the index of symmetrical variation (ISV and keratoconus index (KI at 3 months and in the index of height asymmetry (IHA and minimum radius of curvature (Rmin at 9 months post treatment. On the contrary, the untreated group’s indices showed some significant worsening in ISV, KI, central keratoconus index (CKI, and Rmin. A novel finding in our study was a slight positive shift of anterior asphericity in the 6 mm, 7 mm, and 8 mm 3 months after treatment, which had a correlation with BCVA (R2=0.390, p=0.053 and a strong correlation with maximum K-reading (R2=0.690, p=0.005. However, the untreated group had no significant changes after 1 year.Conclusion: The corneal asymmetrical shape is associated with the spherical aberration alteration

  16. Evaluation of corneal changes after myopic LASIK using the Pentacam®

    Directory of Open Access Journals (Sweden)

    Khairat YM

    2013-09-01

    Full Text Available Yehia M Khairat, Yasser H Mohamed, Ismail ANO Moftah, Narden N Fouad Department of Ophthalmology, Faculty of Medicine, El-Minya University, Egypt Background: In this study, we used a Pentacam® device to evaluate the corneal changes that occur after laser-assisted in situ keratomileusis (LASIK. Methods: Our study included 60 eyes of 32 patients. All patients were treated for myopia and myopic astigmatism using LASIK. The eyes were examined preoperatively and 3 months postoperatively using a Pentacam to assess corneal changes with regard to curvature, elevation, and asphericity of the cornea. Results: A statistically significant decrease in mean keratometric power of the anterior corneal surface (P = 0.001 compared with its pre-LASIK value was detected after 3 months, but there was no significant change in keratometric power of the posterior surface (P = 0.836. Asphericity (Q-value of the anterior and posterior surfaces increased significantly after LASIK (P = 0.001. A significant forward bulge of the anterior corneal surface 4 mm and 7 mm from the central zone was detected 3 months post-LASIK (P = 0.001 for both, but there was no significant increase in posterior elevation at 4 mm and 7 mm from the center (P = 0.637 and P = 0.26, respectively. No cases of post-LASIK ectasia were detected. Correlation between different parameters of the corneal surface revealed an indirect relation between changes in pachymetry and anterior corneal elevation at 4 mm and 7 mm from the central zone (r = −0.27, P = 0.13, and r = −0.37, P = 0.04, respectively, and a direct proportion between changes in pachymetry and mean keratometric power of the anterior and posterior corneal surfaces (r = 0.7, P = 0.001 and r = 0.4, P = 0.028, respectively. Conclusion: LASIK causes significant changes at the anterior corneal surface but the effect is subtle and insignificant at the posterior surface. Keywords: LASIK, laser-assisted in situ keratomileusis, Pentacam®, corneal

  17. Precision alignment and calibration of optical systems using computer generated holograms

    Science.gov (United States)

    Coyle, Laura Elizabeth

    As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the

  18. The Imaging X-Ray Polarimetry Explorer (IXPE)

    Science.gov (United States)

    Weisskopf, Martin C.; Ramsey, Brian; O’Dell, Stephen; Tennant, Allyn; Elsner, Ronald; Soffita, Paolo; Bellazzini, Ronaldo; Costa, Enrico; Kolodziejczak, Jeffery; Kaspi, Victoria; hide

    2016-01-01

    The Imaging X-ray Polarimetry Explorer (IXPE) is an exciting international collaboration for a scientific mission that dramatically brings together the unique talents of the partners to expand observation space by simultaneously adding polarization measurements to the array of source properties currently measured (energy, time, and location). IXPE uniquely brings to the table polarimetric imaging. IXPE will thus open new dimensions for understanding how X-ray emission is produced in astrophysical objects, especially systems under extreme physical conditions-such as neutron stars and black holes. Polarization singularly probes physical anisotropies-ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin-that are not otherwise measurable. Hence, IXPE complements all other investigations in high-energy astrophysics by adding important and relatively unexplored information to the parameter space for studying cosmic X-ray sources and processes, as well as for using extreme astrophysical environments as laboratories for fundamental physics.

  19. Ta2O5/ Al2O3/ SiO2 - antireflective coating for non-planar optical surfaces by atomic layer deposition

    Science.gov (United States)

    Pfeiffer, K.; Schulz, U.; Tünnermann, A.; Szeghalmi, A.

    2017-02-01

    Antireflective coatings are essential to improve transmittance of optical elements. Most research and development of AR coatings has been reported on a wide variety of plane optical surfaces; however, antireflection is also necessary on nonplanar optical surfaces. Physical vapor deposition (PVD), a common method for optical coatings, often results in thickness gradients on strongly curved surfaces, leading to a failure of the desired optical function. In this work, optical thin films of tantalum pentoxide, aluminum oxide and silicon dioxide were prepared by atomic layer deposition (ALD), which is based on self-limiting surface reactions. The results demonstrate that ALD optical layers can be deposited on both vertical and horizontal substrate surfaces with uniform thicknesses and the same optical properties. A Ta2O5/Al2O3/ SiO2 multilayer AR coating (400-700 nm) was successfully applied to a curved aspheric glass lens with a diameter of 50 mm and a center thickness of 25 mm.

  20. Scanning laser microscope for imaging nanostructured superconductors

    International Nuclear Information System (INIS)

    Ishida, Takekazu; Arai, Kohei; Akita, Yukio; Miyanari, Mitsunori; Minami, Yusuke; Yotsuya, Tsutomu; Kato, Masaru; Satoh, Kazuo; Uno, Mayumi; Shimakage, Hisashi; Miki, Shigehito; Wang, Zhen

    2010-01-01

    The nanofabrication of superconductors yields various interesting features in superconducting properties. A variety of different imaging techniques have been developed for probing the local superconducting profiles. A scanning pulsed laser microscope has been developed by the combination of the XYZ piezo-driven stages and an optical fiber with an aspheric focusing lens. The scanning laser microscope is used to understand the position-dependent properties of a superconducting MgB 2 stripline of length 100 μm and width of 3 μm under constant bias current. Our results show that the superconducting stripline can clearly be seen in the contour image of the scanning laser microscope on the signal voltage. It is suggested from the observed image that the inhomogeneity is relevant in specifying the operating conditions such as detection efficiency of the sensor.

  1. Gamma-ray burst progenitors and the population of rotating Wolf-Rayet stars.

    Science.gov (United States)

    Vink, Jorick S

    2013-06-13

    In our quest for gamma-ray burst (GRB) progenitors, it is relevant to consider the progenitor evolution of normal supernovae (SNe). This is largely dominated by mass loss. We discuss the mass-loss rate for very massive stars up to 300M⊙. These objects are in close proximity to the Eddington Γ limit. We describe the new concept of the transitional mass-loss rate, enabling us to calibrate wind mass loss. This allows us to consider the occurrence of pair-instability SNe in the local Universe. We also discuss luminous blue variables and their link to luminous SNe. Finally, we address the polarization properties of Wolf-Rayet (WR) stars, measuring their wind asphericities. We argue to have found a group of rotating WR stars that fulfil the required criteria to make long-duration GRBs.

  2. Method of improving the performance of lenses for use in thermal infrared

    Science.gov (United States)

    McDowell, M. W.; Klee, H. W.

    1980-10-01

    A method is described whereby the field performance of an all-germanium triplet, as used for imaging radiation in the 8 to 13 micron waveband, can be improved. The principle of the method, which could also be used to improve the performance of achromatic triplets or aspherized doublets, involves the use of a field flattener lens which replaces the germanium window of the detector. The curvature of this lens can be optimized to minimize field curvature, which together with chromatic aberration is one of the most serious residuals of thermal imaging systems with relative apertures of around f/0.7. It is also shown that for such relative apertures, and for typical fields of less than 15 degrees, at 100 mm focal length, the location of the aperture stop is not a significant design parameter. This arises as a result of the intrinsic optical properties of germanium.

  3. Trends in contemporary mathematics

    CERN Document Server

    Strickland, Elisabetta

    2014-01-01

    This book covers a wide spectrum of hot topics and current trends in mathematics, including noncommutative algebra via deformation theory,  optimal transportation, nonlinear potential theory, kinetic theory and gas dynamics, geometric numerical integration, finite simple groups of small essential dimension, optimal control problems, extended Dynkin diagrams, spin glasses, aspherical closed manifolds, Boltzmann systems, birational geometry of projective varieties and directed graphs, nonlinear diffusion, geometric constructions of extremal metrics on complex manifolds, and Pell’s equation in polynomials. The book comprises a selection of contributions by leading international mathematicians who were speakers at the "INdAM Day", an initiative dating back to 2004 at which the most recent developments in contemporary mathematics are presented.

  4. Mass Transfer in Mira-Type Binaries

    Directory of Open Access Journals (Sweden)

    Mohamed S.

    2012-06-01

    Full Text Available Detached, symbiotic binaries are generally assumed to interact via Bondi-Hoyle-Littleton (BHL wind accretion. However, the accretion rates and outflow geometries that result from this mass-transfer mechanism cannot adequately explain the observations of the nearest and best studied symbiotic binary, Mira, or the formation of some post-AGB binaries, e.g. barium stars. We propose a new mass-transfer mode for Mira-type binaries, which we call ‘wind Roche-lobe overflow’ (WRLOF, and which we demonstrate with 3D hydrodynamic simulations. Importantly, we show that the circumstellar outflows which result from WRLOF tend to be highly aspherical and strongly focused towards the binary orbital plane. Furthermore, the subsequent mass-transfer rates are at least an order of magnitude greater than the analogous BHL values. We discuss the implications of these results for the shaping of bipolar (proto-planetary nebulae and other related systems.

  5. Solar-Pumped TEM₀₀ Mode Nd:YAG laser.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2013-10-21

    Here we show a significant advance in solar-pumped laser beam brightness by utilizing a 1.0 m diameter Fresnel lens and a 3 mm diameter Nd:YAG single-crystal rod. The incoming solar radiation is firstly focused by the Fresnel lens on a solar tracker. A large aspheric lens and a 2D-CPC concentrator are then combined to further compress the concentrated solar radiation along the thin laser rod within a V-shaped pumping cavity. 2.3 W cw TEM₀₀ (M² ≤ 1.1) solar laser power is finally produced, attaining 1.9 W laser beam brightness figure of merit, which is 6.6 times higher than the previous record. For multimode operation, 8.1 W cw laser power is produced, corresponding to 143% enhancement in collection efficiency.

  6. 25  W/m2 collection efficiency solar-pumped Nd:YAG laser by a heliostat-parabolic mirror system.

    Science.gov (United States)

    Liang, D; Almeida, J; Vistas, C R

    2016-09-20

    A large aspheric fused silica lens was used to couple efficiently the concentrated solar radiation from the focal zone of a 1.5-m-diameter primary concentrator into a 4-mm-diameter, 35-mm-long Nd:YAG single-crystal rod within a conical pump cavity. Continuous-wave laser power of 29.3 W was measured, attaining 25.0  W/m2 solar laser collection efficiency, corresponding to a 19% increase over the previous record. Its laser beam figure of merit-the ratio between laser power and the product of Mx2, My2 beam quality factors-of 0.01 W is 1.6 times higher than that of a direct tracking solar laser with 30  W/m2 collection efficiency. A strong dependency of solar laser power on laser resonator cavity length was found.

  7. Optics of the human cornea influence the accuracy of stereo eye-tracking methods: a simulation study.

    Science.gov (United States)

    Barsingerhorn, A D; Boonstra, F N; Goossens, H H L M

    2017-02-01

    Current stereo eye-tracking methods model the cornea as a sphere with one refractive surface. However, the human cornea is slightly aspheric and has two refractive surfaces. Here we used ray-tracing and the Navarro eye-model to study how these optical properties affect the accuracy of different stereo eye-tracking methods. We found that pupil size, gaze direction and head position all influence the reconstruction of gaze. Resulting errors range between ± 1.0 degrees at best. This shows that stereo eye-tracking may be an option if reliable calibration is not possible, but the applied eye-model should account for the actual optics of the cornea.

  8. Termoterapia transpupilar como opção terapêutica para hemangioma circunscrito de coróide: relato de caso

    Directory of Open Access Journals (Sweden)

    Roizenblatt Jaime

    2002-01-01

    Full Text Available Os autores descrevem um caso de hemangioma circunscrito de coróide, com descolamento de retina associado, tratado por meio de termoterapia transpupilar com laser de diodo. Os parâmetros utilizados foram: 900 mW, mira de 4,2 mm, tempo de 3 minutos, lente QuadrAspheric (Volkâ com fator de magnificação de 1,97. Um mês após o tratamento ocorreu redução significativa do hemangioma, com recuperação integral da visão deste olho. São feitas considerações a respeito do método, o qual mostra-se promissor no tratamento destes tumores vasculares.

  9. Characterisation of surface roughness for ultra-precision freeform surfaces

    International Nuclear Information System (INIS)

    Li Huifen; Cheung, C F; Lee, W B; To, S; Jiang, X Q

    2005-01-01

    Ultra-precision freeform surfaces are widely used in many advanced optics applications which demand for having surface roughness down to nanometer range. Although a lot of research work has been reported on the study of surface generation, reconstruction and surface characterization such as MOTIF and fractal analysis, most of them are focused on axial symmetric surfaces such as aspheric surfaces. Relative little research work has been found in the characterization of surface roughness in ultra-precision freeform surfaces. In this paper, a novel Robust Gaussian Filtering (RGF) method is proposed for the characterisation of surface roughness for ultra-precision freeform surfaces with known mathematic model or a cloud of discrete points. A series of computer simulation and measurement experiments were conducted to verify the capability of the proposed method. The experimental results were found to agree well with the theoretical results

  10. On groups of pl-homeomorphisms of the real line

    CERN Document Server

    Bieri, Robert

    2016-01-01

    Richard Thompson's famous group F has the striking property that it can be realized as a dense subgroup of the group of all orientation-preserving homeomorphisms of the unit interval, but it can also be given by a simple 2-generator-2-relator presentation, in fact as the fundamental group of an aspherical complex with only two cells in each dimension. This monograph studies a natural generalization of F that also includes Melanie Stein's generalized F-groups. The main aims of this monograph are the determination of isomorphisms among the generalized F-groups and the study of their automorphism groups. This book is aimed at graduate students (or teachers of graduate students) interested in a class of examples of torsion-free infinite groups with elements and composition that are easy to describe and work with, but have unusual properties and surprisingly small presentations in terms of generators and defining relations.

  11. Optical design methods, applications, and large optics; Proceedings of the Meeting, Hamburg, Federal Republic of Germany, Sept. 19-21, 1988

    Science.gov (United States)

    Masson, Andre; Schulte In den Baeumen, J.; Zuegge, Hannfried

    1989-04-01

    Recent advances in the design of large optical components are discussed in reviews and reports. Sections are devoted to calculation and optimization methods, optical-design software, IR optics, diagnosis and tolerancing, image formation, lens design, and large optics. Particular attention is given to the use of the pseudoeikonal in optimization, design with nonsequential ray tracing, aspherics and color-correcting elements in the thermal IR, on-line interferometric mirror-deforming measurement with an Ar-ion laser, and the effect of ametropia on laser-interferometric visual acuity. Also discussed are a holographic head-up display for air and ground applications, high-performance objectives for a digital CCD telecine, the optics of the ESO Very Large Telescope, static wavefront correction by Linnik interferometry, and memory-saving techniques in damped least-squares optimization of complex systems.

  12. Transport tensors in perfectly aligned low-density fluids: Self-diffusion and thermal conductivity

    International Nuclear Information System (INIS)

    Singh, G. S.; Kumar, B.

    2001-01-01

    The modified Taxman equation for the kinetic theory of low-density fluids composed of rigid aspherical molecules possessing internal degrees of freedom is generalized to obtain the transport tensors in a fluid of aligned molecules. The theory takes care of the shape of the particles exactly but the solution has been obtained only for the case of perfectly aligned hard spheroids within the framework of the first Sonine polynomial approximation. The expressions for the thermal-conductivity components have been obtained for the first time whereas the self-diffusion components obtained here turn out to be exactly the same as those derived by Kumar and Masters [Mol. Phys. >81, 491 (1994)] through the solution of the Lorentz-Boltzmann equation. All our expressions yield correct results in the hard-sphere limit

  13. Topography-guided custom ablation treatment for treatment of keratoconus

    Directory of Open Access Journals (Sweden)

    Rohit Shetty

    2013-01-01

    Full Text Available Keratoconus is a progressive ectatic disorder of the cornea which often presents with fluctuating refraction and high irregular astigmatism. Correcting the vision of these patients is often a challenge because glasses are unable to correct the irregular astigmatism and regular contact lenses may not fit them very well. Topography-guided custom ablation treatment (T-CAT is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and possibly contact lens fit. The aim of the procedure is not to give a complete refractive correction. It has been tried with a lot of success by various groups of refractive surgeons around the world but a meticulous and methodical planning of the procedure is essential to ensure optimum results. In this paper, we attempt to elucidate the planning for a T-CAT procedure for various types of cones and asphericities.

  14. Scanning laser microscope for imaging nanostructured superconductors

    Science.gov (United States)

    Ishida, Takekazu; Arai, Kohei; Akita, Yukio; Miyanari, Mitsunori; Minami, Yusuke; Yotsuya, Tsutomu; Kato, Masaru; Satoh, Kazuo; Uno, Mayumi; Shimakage, Hisashi; Miki, Shigehito; Wang, Zhen

    2010-10-01

    The nanofabrication of superconductors yields various interesting features in superconducting properties. A variety of different imaging techniques have been developed for probing the local superconducting profiles. A scanning pulsed laser microscope has been developed by the combination of the XYZ piezo-driven stages and an optical fiber with an aspheric focusing lens. The scanning laser microscope is used to understand the position-dependent properties of a superconducting MgB 2 stripline of length 100 μm and width of 3 μm under constant bias current. Our results show that the superconducting stripline can clearly be seen in the contour image of the scanning laser microscope on the signal voltage. It is suggested from the observed image that the inhomogeneity is relevant in specifying the operating conditions such as detection efficiency of the sensor.

  15. Uniform LED illuminator for miniature displays

    Science.gov (United States)

    Medvedev, Vladimir; Pelka, David G.; Parkyn, William A.

    1998-10-01

    The Total Internally Reflecting (TIR) lens is a faceted structure composed of prismatic elements that collect a source's light over a much larger angular range than a conventional Fresnel lens. It has been successfully applied to the efficient collimation of light from incandescent and fluorescent lamps, and from light-emitting diodes (LEDs). A novel LED-powered collimating backlight is presented here, for uniformly illuminating 0.25'-diagonal miniature liquid- crystal displays, which are a burgeoning market for pagers, cellular phones, digital cameras, camcorders, and virtual- reality displays. The backlight lens consists of a central dual-asphere refracting section and an outer TIR section, properly curved with a curved exit face.

  16. New method of design of nonimaging concentrators.

    Science.gov (United States)

    Miñano, J C; González, J C

    1992-06-01

    A new method of designing nonimaging concentrators is presented and two new types of concentrators are developed. The first is an aspheric lens, and the second is a lens-mirror combination. A ray tracing of three-dimensional concentrators (with rotational symmetry) is also done, showing that the lens-mirror combination has a total transmission as high as that of the full compound parabolic concentrators, while their depth is much smaller than the classical parabolic mirror-nonimaging concentrator combinations. Another important feature of this concentrator is that the optically active surfaces are not in contact with the receiver, as occurs in other nonimaging concentrators in which the rim of the mirror coincides with the rim of the receiver.

  17. X-ray digital wavefront sensor development

    International Nuclear Information System (INIS)

    Idir, Mourad; Fricker, Sebastien; Modi, Mohammed H.; Potier, Jonathan

    2010-01-01

    Phase contrast imaging (PCI) is a wavefront sensing method that uses a series of intensity images to reconstruct the wavefront. The lateral resolution of PCI is limited mainly by the resolution of the intensity images. PCI provides a simple and efficient technique for characterizing X-ray mirrors. A simulation experiment was conducted to demonstrate the performances of PCI. The results of these experiments have shown the feasibility and potential performances of this method. The use of phase retrieval presents opportunities for greatly simplifying the techniques and apparatus used for characterizing optical surfaces and systems, particularly aspherical surfaces. This paper addresses the design, implementation and performances of an integrated at wavelength digital wavefront sensor.

  18. Optical design of soft multifocal contact lens with uniform optical power in center-distance zone with optimized NURBS.

    Science.gov (United States)

    Vu, Lien T; Chen, Chao-Chang A; Yu, Chia-Wei

    2018-02-05

    This study aims to develop a new optical design method of soft multifocal contact lens (CLs) to obtain uniform optical power in large center-distance zone with optimized Non-Uniform Rational B-spline (NURBS). For the anterior surface profiles of CLs, the NURBS design curves are optimized to match given optical power distributions. Then, the NURBS in the center-distance zones are fitted in the corresponding spherical/aspheric curves for both data points and their centers of curvature to achieve the uniform power. Four cases of soft CLs have been manufactured by casting in shell molds by injection molding and then measured to verify the design specifications. Results of power profiles of these CLs are concord with the given clinical requirements of uniform powers in larger center-distance zone. The developed optical design method has been verified for multifocal CLs design and can be further applied for production of soft multifocal CLs.

  19. Design of 20 W fiber-coupled green laser diode by Zemax

    Science.gov (United States)

    Qi, Yunfei; Zhao, Pengfei; Wu, Yulong; Chen, Yongqi; Zou, Yonggang

    2017-09-01

    We represent a design of a 20 W, fiber-coupled diode laser module based on 26 single emitters at 520 nm. The module can produce more than 20 W output power from a standard fiber with core diameter of 400 μm and numerical aperture (NA) of 0.22. To achieve a 20 W laser beam, the spatial beam combination and polarization beam combination by polarization beam splitter are used to combine output of 26 single emitters into a single beam, and then an aspheric lens is used to couple the combined beam into an optical fiber. The simulation shows that the total coupling efficiency is more than 95%. Project supported by the National Key R& D Program of China (No. 2016YFB0402105), the Key Deployment Program of the Chinese Academy of Sciences (No. KGZD-SW-T01-2), and the National Natural Science Foundation of China (No. 61404135).

  20. Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

    Science.gov (United States)

    Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cédric P.; Ozcan, Aydogan

    2013-03-01

    The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

  1. Astronomical optics and elasticity theory

    CERN Document Server

    Lemaitre, Gerard Rene

    2008-01-01

    Astronomical Optics and Elasticity Theory provides a very thorough and comprehensive account of what is known in this field. After an extensive introduction to optics and elasticity, the book discusses variable curvature and multimode deformable mirrors, as well as, in depth, active optics, its theory and applications. Further, optical design utilizing the Schmidt concept and various types of Schmidt correctors, as well as the elasticity theory of thin plates and shells are elaborated upon. Several active optics methods are developed for obtaining aberration corrected diffraction gratings. Further, a weakly conical shell theory of elasticity is elaborated for the aspherization of grazing incidence telescope mirrors. The very didactic and fairly easy-to-read presentation of the topic will enable PhD students and young researchers to actively participate in challenging astronomical optics and instrumentation projects.

  2. Correction method for the error of diamond tool's radius in ultra-precision cutting

    Science.gov (United States)

    Wang, Yi; Yu, Jing-chi

    2010-10-01

    The compensation method for the error of diamond tool's cutting edge is a bottle-neck technology to hinder the high accuracy aspheric surface's directly formation after single diamond turning. Traditional compensation was done according to the measurement result from profile meter, which took long measurement time and caused low processing efficiency. A new compensation method was firstly put forward in the article, in which the correction of the error of diamond tool's cutting edge was done according to measurement result from digital interferometer. First, detailed theoretical calculation related with compensation method was deduced. Then, the effect after compensation was simulated by computer. Finally, φ50 mm work piece finished its diamond turning and new correction turning under Nanotech 250. Testing surface achieved high shape accuracy pv 0.137λ and rms=0.011λ, which approved the new compensation method agreed with predictive analysis, high accuracy and fast speed of error convergence.

  3. Mechanism of cavitation damage and structure of a cavitating eddy

    International Nuclear Information System (INIS)

    Efimov, A.V.; Vorob'ev, G.A.; Filenko, Yu.I.; Petrov, K.N.

    1976-01-01

    As a result of experimental studies of the structure of a cavitating eddy and the action of single cavitation bubbles on a solid surface the assumption of double nature of cavitation damage forces depending on its regimes was made. The first type of the damage forces is shock waves, appearing around collapsing spherical bubble, the second type is hydraulic impacts of microjets making a hole in a collapsing aspherical bubble. The outward appearance of single microdents differs from each other. The damage of the first type is accompanied by corrosion. The cavitation erosion intensity of the damage of the first type exceeds that of the damage of the second type by one order of magnitude. The values of the porosity of a cavitation eddy, the bubble concentration and the distance between them, the bubble distribution according to the size and the form for the initial cavitation stage are given from holographic investigations

  4. Study of the density of electrons in momentum space in the Al-Li-Cu icosahedral phase by means of positron annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Yoshikazu; Nanao, Susumu [Institute of Industrial Science, The University of Tokyo, Roppongi, Minato, Tokyo 106 (Japan); Tanigawa, Shoichiro [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305 (Japan)

    1997-12-15

    The three-dimensional momentum density of annihilating electron - positron pairs has been studied for a single Al-Li-Cu icosahedral quasicrystal. A direct Fourier transform method is employed to reconstruct the three-dimensional momentum density from measurements of the two-dimensional angular correlation of positron annihilation radiation (2 D-ACAR). The crystallographic anisotropy in the momentum density is observed to be very small. The asphericity of the Fermi surface is not found explicitly within the experimental resolution in the momentum space. The features of the three-dimensional electron - positron momentum density agree with those obtained by means of Compton profile measurement. It is suggested that a strong lattice - electron interaction at the Fermi level occurs in this icosahedral phase. (author)

  5. Anatomically accurate, finite model eye for optical modeling.

    Science.gov (United States)

    Liou, H L; Brennan, N A

    1997-08-01

    There is a need for a schematic eye that models vision accurately under various conditions such as refractive surgical procedures, contact lens and spectacle wear, and near vision. Here we propose a new model eye close to anatomical, biometric, and optical realities. This is a finite model with four aspheric refracting surfaces and a gradient-index lens. It has an equivalent power of 60.35 D and an axial length of 23.95 mm. The new model eye provides spherical aberration values within the limits of empirical results and predicts chromatic aberration for wavelengths between 380 and 750 nm. It provides a model for calculating optical transfer functions and predicting optical performance of the eye.

  6. Optical telescopes for COMPASS RICH1 up-grade

    CERN Document Server

    Sulc, M; Alekseev, M; Angerer, H; Appolonio, M; Birsa, R; Bordalo, P; Bradamante, F; Bressan, A; Busso, L; Chiosso, V M; Ciliberti, P; Colantoni, M L; Costa, S; Dibiase, N; Dafni, T; Dalla Torre, S; Diaz, V; Duic, V; Delagnes, E; Deschamps, H; Eyrich, W; Faso, D; Ferrero, A; Finger, M; Finger, M Jr; Fischer, H; Gerassimov, S; Giorgi, M; Gobbo, B; Hagemann, R; von Harrach, D; Heinsius, F H; Joosten, R; Ketzer, B; Königsmann, K; Kolosov, V N; Konorov, I; Kramer, D; Kunne, F; Levorato, S; Maggiora, A; Magnon, A; Mann, A; Martin, A; Menon, G; Mutter, A; Nähle, O; Neyret, D; Nerling, F; Pagano, P; Paul, S; Panebianco, S; Panzieri, D; Pesaro, G; Pizzolotto, C; Polak, J; Rebourgeard, P; Rocco, E; Robinet, F; Schiavon, P; Schill, C; Schoenmeier, P; Silva, L; Slunecka, M; Steiger, L; Sozzi, F; Svec, M; Tessarotto, F; Teufel, A; Wollny, H

    2006-01-01

    The central photon detection area of the Ring Imaging Cherenkov detector at COMPASS, a particle physics experiment at CERN SPS dedicated to hadron physics, has been upgraded from the previous system formed by wire chambers with CsI layers to a very fast UV extended multi anode photo multiplier tube array (MAPMT), including 576 tubes. The active area covered by the MAPMTs is 7.3 times smaller than the one previously equipped with CsI photocathodes, so 576 optical concentrators transforming the image from the old system focal plane to the new photocathode plane were needed. The telescope system formed by two fused silica lenses was designed, produced and assembled. The first prismatic plano-convex field lens is placed in the focal plane of the RICH mirrors. The second condenser lens is off centered and tilted and has one aspherical surface. All lenses have antireflection coating.

  7. Edges in CNC polishing: from mirror-segments towards semiconductors, paper 1: edges on processing the global surface.

    Science.gov (United States)

    Walker, David; Yu, Guoyu; Li, Hongyu; Messelink, Wilhelmus; Evans, Rob; Beaucamp, Anthony

    2012-08-27

    Segment-edges for extremely large telescopes are critical for observations requiring high contrast and SNR, e.g. detecting exo-planets. In parallel, industrial requirements for edge-control are emerging in several applications. This paper reports on a new approach, where edges are controlled throughout polishing of the entire surface of a part, which has been pre-machined to its final external dimensions. The method deploys compliant bonnets delivering influence functions of variable diameter, complemented by small pitch tools sized to accommodate aspheric mis-fit. We describe results on witness hexagons in preparation for full size prototype segments for the European Extremely Large Telescope, and comment on wider applications of the technology.

  8. Limitations in accurate electron density studies

    International Nuclear Information System (INIS)

    Wal, R. van der.

    1982-01-01

    Most of X-ray diffraction studies are devoted to the determination of three-dimensional crystal structures from the electron density distributions. In these cases the density distributions are described by the independent atom model (IAM model), which consists of a superposition of spherically averaged free atom densities, which are smeared by thermal vibrations. During the last few decades studies have been made into the deviations of the density distribution from the IAM model, which enables a study of the chemical binding between atoms. The total density can be described using pseudo-atom multipole models as a superposition of aspherical pseudo-atom densities. A fundamental problem is that the separation of this density into an IAM and a deformation part is not unique. This thesis considers the problem and besides deformation densities from X-ray diffraction also considers the corresponding deformation electric field and deformation potential. (C.F.)

  9. The great wall in the CfA survey: Its origin and imprint on the microwave background radiation

    International Nuclear Information System (INIS)

    Atrio-Barandela, F.; Kashlinsky, A.

    1990-01-01

    The Great Wall (GW) found in the latest CfA survey has clearly started out as an aspherical overdense region. We model its evolution after recombination and the imprint its time-dependent gravitational potential leaves on the microwave background radiation (MBR). We approximate GW as an oblate ellipsoid and show that it started at recombination with an almost spherical shape, but with an initial density contrast, δ i , much smaller than it had to be in the spherical model in order to reach the observed GW density contrast of q∝5. The resultant δ i is compatible with the r.m.s. value of δρ/ρ on the GW scale at recombination for models with the n -6 -5 depending on Ω and q. Therefore, MBR observations in that direction can further constrain Ω and the bias factor of the light distribution. (orig.)

  10. Optical system design, analysis, and production; Proceedings of the Meeting, Geneva, Switzerland, April 19-22, 1983

    Science.gov (United States)

    Rogers, P. J.; Fischer, R. E.

    1983-01-01

    Topics considered include: optical system requirements, analysis, and system engineering; optical system design using microcomputers and minicomputers; optical design theory and computer programs; optical design methods and computer programs; optical design methods and philosophy; unconventional optical design; diffractive and gradient index optical system design; optical production and system integration; and optical systems engineering. Particular attention is given to: stray light control as an integral part of optical design; current and future directions of lens design software; thin-film technology in the design and production of optical systems; aspherical lenses in optical scanning systems; the application of volume phase holograms to avionic displays; the effect of lens defects on thermal imager performance; and a wide angle zoom for the Space Shuttle.

  11. Figure and finish characterization of high performance metal mirrors

    International Nuclear Information System (INIS)

    Takacs, P.Z.; Church, E.L.

    1991-10-01

    Most metal mirrors currently used in synchrotron radiation (SR) beam lines to reflect soft x-rays are made of electroless nickel plate on an aluminum substrate. This material combination has allowed optical designers to incorporate exotic cylindrical aspheres into grazing incidence x-ray beam-handling systems by taking advantage of single-point diamond machining techniques. But the promise of high-quality electroless nickel surfaces has generally exceeded the performance. We will examine the evolution of electroless nickel surfaces through a study of the quality of mirrors delivered for use at the National Synchrotron Light Source over the past seven years. We have developed techniques to assess surface quality based on the measurement of surface roughness and figure errors with optical profiling instruments. It is instructive to see how the quality of the surface is related to the complexity of the machine operations required to produce it

  12. Optical Design of the far Ultraviolet Imaging Spectrograph

    Directory of Open Access Journals (Sweden)

    K. S. Ryu

    1998-12-01

    Full Text Available We present the design specifications and the performance estimation of the FUVS (Far Ultraviolet Spectrograph proposed for the observations of aurora, day/night airglow and astronomical objects on small satelltes in the spectral range of . The design of FUVS is carried out with the full consideration of optical characteristics of the grating and the aspheric substrate. Two independent methods, ray-tracing and the wave front aberration theory, are employed to estimate the performance of the optical design and it is verified that both procedures yield the resolution of in the entire spectral range. MDF (Minimum Detectable Flux is also estimated using the known characteristics of the reflecting material and MCP, to study the feasibility of detection for faint emission lines from the hot interstellar plasmas. The results give that the observations from 1 day to 1 week, depending on the line intensity, can detect such faint emission lines from diffuse interstellar plasmas.

  13. High-throughput optical system for HDES hyperspectral imager

    Science.gov (United States)

    Václavík, Jan; Melich, Radek; Pintr, Pavel; Pleštil, Jan

    2015-01-01

    Affordable, long-wave infrared hyperspectral imaging calls for use of an uncooled FPA with high-throughput optics. This paper describes the design of the optical part of a stationary hyperspectral imager in a spectral range of 7-14 um with a field of view of 20°×10°. The imager employs a push-broom method made by a scanning mirror. High throughput and a demand for simplicity and rigidity led to a fully refractive design with highly aspheric surfaces and off-axis positioning of the detector array. The design was optimized to exploit the machinability of infrared materials by the SPDT method and a simple assemblage.

  14. An advanced KB mirror pair for microfocusing

    CERN Document Server

    Ferme, J J

    2001-01-01

    A new range of micro-focusing mirrors based on KB pairs has been developed by SESO for Beamline Nanospectroscopy at the Elettra Storage Ring in Trieste, Italy. Both the focusing and the aspheric shape are adjustable with stepper motors. The goal of the beamline is to have a high photon density spot with a variable size in the experimental chamber over the whole soft X-ray range. The estimated dimension of the final spot should be smaller than 4 mu m sup 2 FWHM, with a photon density of the order of 10 sup 1 sup 3 photons/s mu m sup 2; this may be achieved only by accepting an angular divergence on these mirrors of between 5 and 10 mrad. This condition can be fulfilled only with elliptical (or plane elliptical) mirrors with very limited residual slope errors (below 1 mu rad RMS) that are able to correct even small focal distance errors.

  15. Hough transform used on the spot-centroiding algorithm for the Shack-Hartmann wavefront sensor

    Science.gov (United States)

    Chia, Chou-Min; Huang, Kuang-Yuh; Chang, Elmer

    2016-01-01

    An approach to the spot-centroiding algorithm for the Shack-Hartmann wavefront sensor (SHWS) is presented. The SHWS has a common problem, in that while measuring high-order wavefront distortion, the spots may exceed each of the subapertures, which are used to restrict the displacement of spots. This artificial restriction may limit the dynamic range of the SHWS. When using the SHWS to measure adaptive optics or aspheric lenses, the accuracy of the traditional spot-centroiding algorithm may be uncertain because the spots leave or cross the confined area of the subapertures. The proposed algorithm combines the Hough transform with an artificial neural network, which requires no confined subapertures, to increase the dynamic range of the SHWS. This algorithm is then explored in comprehensive simulations and the results are compared with those of the existing algorithm.

  16. Evolved Stars, Masers And Polarization Submm/mm/cm QUESO Workshop 2017 (QUESO2017), Centimetre-Sub-Millimetre Q&U (and V) European Southern Observatory Workshop, held 25-27 October, 2017 at ESO, Garching bei München, Germany. Online at https://www.eso.org/sci/meetings/2017/QUESO2017.html, id.35

    Science.gov (United States)

    Humphreys, Elizabeth

    2017-11-01

    Cool evolved stars on the Asymptotic Giant Branch (AGB) and Red Supergiants (RSG) often host strong masers, for example from SiO, water and OH. The maser emission can display high degrees of circular and linear polarization, potentially revealing information on magnetic field strength and morphology at different radii in the circumstellar envelopes. In this review, I will describe maser polarization theory and discuss was has been learnt so far from maser observations. I will also discuss dust polarization at (sub)mm wavelengths and the role that full polarization observations using ALMA is going to play in better characterizing evolved stars. Finally, I will talk about the potential impact of magnetic fields in the evolution of the stars, for example the shaping of AGB stars to often highly axisymmetric/aspherical Planetary Nebulae.queso2017queso2017

  17. The application of diffraction grating in the design of virtual reality (VR) system

    Science.gov (United States)

    Chen, Jiekang; Huang, Qitai; Guan, Min

    2017-10-01

    Virtual Reality (VR) products serve for human eyes ultimately, and the optical properties of VR optical systems must be consistent with the characteristic of human eyes. The monocular coaxial VR optical system is simulated in ZEMAX. A diffraction grating is added to the optical surface next to the eye, and the lights emitted from the diffraction grating are deflected, which can forming an asymmetrical field of view(FOV). Then the lateral chromatic aberration caused by the diffraction grating was corrected by the chromatic dispersion of the prism. Finally, the aspheric surface was added to further optimum design. During the optical design of the system, how to balance the dispersion of the diffraction grating and the prism is the main problem. The balance was achieved by adjusting the parameters of the grating and the prism constantly, and then using aspheric surfaces finally. In order to make the asymmetric FOV of the system consistent with the angle of the visual axis, and to ensure the stereo vision area clear, the smaller half FOV of monocular system is required to reach 30°. Eventually, a system with asymmetrical FOV of 30°+40° was designed. In addition, the aberration curve of the system was analyzed by ZEMAX, and the binocular FOV was calculated according to the principle of binocular overlap. The results show that the asymmetry of FOV of VR monocular optical system can fit to human eyes and the imaging quality match for the human visual characteristics. At the same time, the diffraction grating increases binocular FOV, which decreases the requirement for the design FOV of monocular system.

  18. SU-8 Lenses: Simple Methods of Fabrication and Application in Optical Interconnection Between Fiber/LED and Microstructures

    Science.gov (United States)

    Nguyen, Minh-Hang; Nguyen, Hai-Binh; Nguyen, Tuan-Hung; Vu, Xuan-Manh; Lai, Jain-Ren; Tseng, Fan-Gang; Chen, Te-Chang; Lee, Ming-Chang

    2016-05-01

    This paper presents two facile methods to fabricate off-plane lenses made of SU-8, an epoxy-based negative photoresist from MicroChem, on glass for optical interconnection. The methods allow the fabrication of lenses with flexible spot size and focal length depending on SU-8 well size and SU-8 drop volume and viscosity. In the first method, SU-8 drops were applied directly into patterned SU-8 wells with Teflon-coated micropipettes, and were baked to become (a)-spherical lenses. The lens shape and size were mainly determined by SU-8 viscosity, ratio of drop volume to well volume, and baking temperature and time. In the second method, a glass substrate with SU-8 patterned wells was emerged in diluted SU-8, then drawn up and baked to form lenses. The lens shapes and sizes were mainly determined by SU-8 viscosity and well volume. By the two methods, SU-8 lenses were successfully fabricated with spot sizes varying in range from micrometers to hundred micrometers, and focal lengths varying in range of several millimeters, depending on the lens rim diameters and aspheric sag height. Besides, on-plane SU-8 lenses were fabricated by photolithography to work in conjunction with the off-plane SU-8 lenses. The cascaded lenses produced light spots reduced to several micrometers, and they can be applied as a coupler for light coupling from fiber/Light-emitting diode (LED) to microstructures and nanostructures. The results open up the path for fabricating novel optical microsystems for optical communication and optical sensing applications.

  19. Role of short-wavelength filtering lenses in delaying myopia progression and amelioration of asthenopia in juveniles

    Directory of Open Access Journals (Sweden)

    Hai-Lan Zhao

    2017-08-01

    Full Text Available AIM: To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS: Sixty ametropia juveniles (aged range, 11-15y were randomized into two groups: the test group (30 children, 60 eyes, wearing blue-violet light filtering lenses; and the control group (30 children, 60 eyes, wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity (glare and non-glare under bright and dark conditions, accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment. RESULTS: After 1y of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups (P>0.05. Under bright conditions, the contrast sensitivities at low and medium-frequency grating (vision angles of 6.3°, 4.0°, and 2.5° with glare in the test group were significantly higher than in the control group (P0.05. In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated (P0.05, and the asthenopia grating was not significantly decreased (P>0.05. In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group (P0.05. CONCLUSION: A 1-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses (blue/violet-light filters increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared

  20. Stability of therapeutic retreatment of corneal wavefront customized ablation with the SCHWIND CAM: 4-year data.

    Science.gov (United States)

    Aslanides, Ioannis M; Kolli, Sai; Padroni, Sara; Padron, Sara; Arba Mosquera, Samuel

    2012-05-01

    To evaluate the long-term outcomes of aspheric corneal wavefront ablation profiles for excimer laser retreatment. Eighteen eyes that had previously undergone LASIK or photorefractive keratectomy (PRK) were retreated with LASIK using the corneal wavefront ablation profile. Custom Ablation Manager (SCHWIND eye-tech-solutions, Kleinostheim, Germany) software and the ESIRIS flying spot excimer laser system (SCHWIND) were used to perform the ablations. Refractive outcomes and wavefront data are reported up to 4 years after retreatment. Pre- and postoperative data were compared with Student t tests and (multivariate) correlation tests. P<.05 was considered statistically significant. A bilinear correlation of various postoperative wavefront aberrations versus planned correction and preoperative aberration was performed. Mean manifest refraction spherical equivalent (MRSE) before retreatment was -0.38±1.85 diopters (D) and -0.09±0.22 D at 6 months and -0.10±0.38 D at 4 years postoperatively. The reduction in MRSE was statistically significant at both postoperative time points (P<.005). Postoperative aberrations were statistically lower (spherical aberration P<.05; coma P<.005; root-mean-square higher order aberration P<.0001) at 4 years postoperatively. Distribution of the postoperative uncorrected distance visual acuity (P<.0001) and corrected distance visual acuity (P<.01) were statistically better than preoperative values. Aspheric corneal wavefront customization with the ESIRIS yields visual, optical, and refractive results comparable to those of other wavefront-guided customized techniques for the correction of myopia and myopic astigmatism. The corneal wavefront customized approach shows its strength in cases where abnormal optical systems are expected. Systematic wavefront customized corneal ablation appears safe and efficacious for retreatment cases. Copyright 2012, SLACK Incorporated.

  1. The effect of static cyclotorsion compensation on refractive and visual outcomes using the Schwind Amaris laser platform for the correction of high astigmatism.

    Science.gov (United States)

    Aslanides, Ioannis M; Toliou, Georgia; Padroni, Sara; Arba Mosquera, Samuel; Kolli, Sai

    2011-06-01

    To compare the refractive and visual outcomes using the Schwind Amaris excimer laser in patients with high astigmatism (>1D) with and without the static cyclotorsion compensation (SCC) algorithm available with this new laser platform. 70 consecutive eyes with ≥1D astigmatism were randomized to treatment with compensation of static cyclotorsion (SCC group- 35 eyes) or not (control group- 35 eyes). A previously validated optimized aspheric ablation algorithm profile was used in every case. All patients underwent LASIK with a microkeratome cut flap. The SCC and control group did not differ preoperatively, in terms of refractive error, magnitude of astigmatism or in terms of cardinal or oblique astigmatism. Following treatment, average deviation from target was SEq +0.16D, SD±0.52 D, range -0.98 D to +1.71 D in the SCC group compared to +0.46 D, SD±0.61 D, range -0.25 D to +2.35 D in the control group, which was statistically significant (p<0.05). Following treatment, average astigmatism was 0.24 D (SD±0.28 D, range -1.01 D to 0.00 D) in the SCC group compared to 0.46 D (SD±0.42 D, range -1.80 D to 0.00 D) in the control group, which was highly statistically significant (p<0.005). There was no statistical difference in the postoperative uncorrected vision when the aspheric algorithm was used although there was a trend to increased number of lines gained in the SCC group. This study shows that static cyclotorsion is accurately compensated for by the Schwind Amaris laser platform. The compensation of static cyclotorsion in patients with moderate astigmatism produces a significant improvement in refractive and astigmatic outcomes than when not compensated. Copyright © 2011 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  2. Effect of the internal optics on the outcome of custom-LASIK in an eye model

    Science.gov (United States)

    Manns, Fabrice; Ho, Arthur; Parel, Jean-Marie

    2004-07-01

    Purpose. The purpose of this study was to evaluate if changes in the aberration-contribution of the internal optics of the eye have a significant effect on the outcome of wavefront-guided corneal reshaping. Methods. The Navarro-Escudero eye model was simulated using optical analysis software. The eye was rendered myopic by shifting the plane of the retina. Custom-LASIK was simulated by changing the radius of curvature and asphericity of the anterior corneal surface of the eye model. The radius of curvature was adjusted to provide a retinal conjugate at infinity. Three approaches were used to determine the postoperative corneal asphericity: minimizing third-order spherical aberration, minimizing third-order coma, and maximizing the Strehl ratio. The aberration contribution of the anterior corneal surface and internal optics was calculated before and after each simulated customized correction. Results. For a 5.2mm diameter pupil, the contribution of the anterior corneal surface to third-order spherical aberration and coma (in micrometers) was 2.22 and 2.49 preop, -0.36 and 2.83 postop when spherical aberration is minimized, 5.88 and 1.10 postop when coma is minimized, and -0.63 and 2.91 postop when Strehl ratio is maximized. The contribution of the internal optics of the eye to spherical aberration and coma for the same four conditions was: 0.43 and -1.13, 0.37 and -1.10, 0.37 and -1.10 and 0.37 and -1.10, respectively. Conclusion. In the model eye, the contribution of the internal optics of the eye to the change in the ocular aberration state is negligible.

  3. 3–10 keV Xe+ ion beam machining of ultra low thermal expansion glasses for EUVL projection optics: Evaluation of surface roughness

    International Nuclear Information System (INIS)

    Morikawa, K.; Kamijo, K.; Morijiri, K.; Pahlovy, S.A.; Aikawa, N.; Miyamoto, I.

    2012-01-01

    In order to obtain surface figure error of 0.15 nm rms and surface roughness (R rms ) of 0.12 nm rms for aspherical substrates in EUVL tools, ion beam figuring may be adopted to final surface figure error correction of aspherical substrates. During figure error correction, machined surface of the substrate becomes rougher than the pre-finished one. Therefore, we investigated the machined depth and ion energy dependences of R rms (measured by an AFM) of substrates machined by 3–10 keV Xe + ion beam, and compared them with the results obtained for Ar + ion beam. Result shows that the R rms s of CLEARCERAM®-Z, Zerodur® and ULE® substrates machined to the depth of 50 nm by 3–10 keV Xe + ion beam at the normal ion incidence angle become approximately 0.25, 0.28 and 0.15 nm rms, respectively. Those values are larger than the pre-finished substrates (0.07–0.09 nm rms), but smaller than that (0.60 nm rms for CLEARCERAM®-Z, 0.61 nm rms for Zerodur® and 0.18 nm rms for ULE®) of the substrates machined by Ar + ion beam. Moreover, the R rms s merely increase with increasing ion energy. The R rms s of the ULE® substrate machined by 3–10 keV Xe + ion beam rapidly increase with increasing machined depth, then saturate at machined depth of 10–50 nm. The saturated values of the R rms s are 0.12 and 0.15 nm rms for 3 and 10 keV Xe + ion beam respectively. We suggest that the 3 keV Xe + ion beam machining can be applicable for final shape correction of ULE® substrates for EUVL projection optics in association with considering further ultra smoothing process such as Si deposition or low energy ion beam smoothing.

  4. Identification of a jet-driven supernova remnant in the Small Magellanic Cloud: Possible evidence for the enhancement of bipolar explosions at low metallicity

    International Nuclear Information System (INIS)

    Lopez, Laura A.; Castro, Daniel; Slane, Patrick O.; Ramirez-Ruiz, Enrico; Badenes, Carles

    2014-01-01

    Recent evidence has suggested that the supernova remnant (SNR) 0104–72.3 in the Small Magellanic Cloud (SMC) may be the result of a 'prompt' Type Ia SN on the basis of enhanced iron abundances and its association with a star-forming region. In this paper, we present evidence that SNR 0104–72.3 arose from a jet-driven bipolar core-collapse (CC) SN. Specifically, we use serendipitous Chandra data of SNR 0104–72.3 taken because of its proximity to the calibration source SNR E0102–72.3. We analyze 56 Advanced CCD Imaging Spectrometer (ACIS) observations of SNR 0104–72.3 to produce imaging and spectra with an effective exposure of 528.6 ks. We demonstrate that SNR 0104–72.3 is highly elliptical relative to other nearby young SNRs, suggesting a CC SN origin. Furthermore, we compare ejecta abundances derived from spectral fits to nucleosynthetic yields of Type Ia and CC SNe, and we find that the iron, neon, and silicon abundances are consistent with either a spherical CC SN of a 18-20 M ☉ progenitor or an aspherical CC SN of a 25 M ☉ progenitor. We show that the star formation history at the site of SNR 0104–72.3 is also consistent with a CC origin. Given the bipolar morphology of the SNR, we favor the aspherical CC SN scenario. This result may suggest jet-driven SNe occur frequently in the low-metallicity environment of the SMC, consistent with the observational and theoretical work on broad-line Type Ic SNe and long-duration gamma-ray bursts.

  5. LDR segmented mirror technology assessment study

    Science.gov (United States)

    Krim, M.; Russo, J.

    1983-01-01

    In the mid-1990s, NASA plans to orbit a giant telescope, whose aperture may be as great as 30 meters, for infrared and sub-millimeter astronomy. Its primary mirror will be deployed or assembled in orbit from a mosaic of possibly hundreds of mirror segments. Each segment must be shaped to precise curvature tolerances so that diffraction-limited performance will be achieved at 30 micron (nominal operating wavelength). All panels must lie within 1 micron on a theoretical surface described by the optical precipitation of the telescope's primary mirror. To attain diffraction-limited performance, the issues of alignment and/or position sensing, position control of micron tolerances, and structural, thermal, and mechanical considerations for stowing, deploying, and erecting the reflector must be resolved. Radius of curvature precision influences panel size, shape, material, and type of construction. Two superior material choices emerged: fused quartz (sufficiently homogeneous with respect to thermal expansivity to permit a thin shell substrate to be drape molded between graphite dies to a precise enough off-axis asphere for optical finishing on the as-received a segment) and a Pyrex or Duran (less expensive than quartz and formable at lower temperatures). The optimal reflector panel size is between 1-1/2 and 2 meters. Making one, two-meter mirror every two weeks requires new approaches to manufacturing off-axis parabolic or aspheric segments (drape molding on precision dies and subsequent finishing on a nonrotationally symmetric dependent machine). Proof-of-concept developmental programs were identified to prove the feasibility of the materials and manufacturing ideas.

  6. Hirshfeld atom refinement for modelling strong hydrogen bonds.

    Science.gov (United States)

    Woińska, Magdalena; Jayatilaka, Dylan; Spackman, Mark A; Edwards, Alison J; Dominiak, Paulina M; Woźniak, Krzysztof; Nishibori, Eiji; Sugimoto, Kunihisa; Grabowsky, Simon

    2014-09-01

    High-resolution low-temperature synchrotron X-ray diffraction data of the salt L-phenylalaninium hydrogen maleate are used to test the new automated iterative Hirshfeld atom refinement (HAR) procedure for the modelling of strong hydrogen bonds. The HAR models used present the first examples of Z' > 1 treatments in the framework of wavefunction-based refinement methods. L-Phenylalaninium hydrogen maleate exhibits several hydrogen bonds in its crystal structure, of which the shortest and the most challenging to model is the O-H...O intramolecular hydrogen bond present in the hydrogen maleate anion (O...O distance is about 2.41 Å). In particular, the reconstruction of the electron density in the hydrogen maleate moiety and the determination of hydrogen-atom properties [positions, bond distances and anisotropic displacement parameters (ADPs)] are the focus of the study. For comparison to the HAR results, different spherical (independent atom model, IAM) and aspherical (free multipole model, MM; transferable aspherical atom model, TAAM) X-ray refinement techniques as well as results from a low-temperature neutron-diffraction experiment are employed. Hydrogen-atom ADPs are furthermore compared to those derived from a TLS/rigid-body (SHADE) treatment of the X-ray structures. The reference neutron-diffraction experiment reveals a truly symmetric hydrogen bond in the hydrogen maleate anion. Only with HAR is it possible to freely refine hydrogen-atom positions and ADPs from the X-ray data, which leads to the best electron-density model and the closest agreement with the structural parameters derived from the neutron-diffraction experiment, e.g. the symmetric hydrogen position can be reproduced. The multipole-based refinement techniques (MM and TAAM) yield slightly asymmetric positions, whereas the IAM yields a significantly asymmetric position.

  7. Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches.

    Science.gov (United States)

    Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose-Manuel

    2015-01-01

    To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens' back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p<0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p<0.05). Significant reduction was found over time in CCA (p=0.001) and anterior corneal asphericity in both groups (p<0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p<0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p<0.05). Short-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apical-touch was associated with greater corneal flattening in comparison to three-point-touch lens wear. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  8. Visual performance in cataract patients with low levels of postoperative astigmatism: full correction versus spherical equivalent correction

    Directory of Open Access Journals (Sweden)

    Lehmann RP

    2012-03-01

    Full Text Available Robert P Lehmann1, Diane M Houtman21Lehmann Eye Center, Nacogdoches, TX, 2Alcon Research Ltd, Fort Worth, TX, USAPurpose: To evaluate whether visual performance could be improved in pseudophakic subjects by correcting low levels of postoperative astigmatism.Methods: An exploratory, noninterventional study was conducted using subjects who had been implanted with an aspheric intraocular lens and had 0.5–0.75 diopter postoperative astigmatism. Monocular visual performance using full correction was compared with visual performance using spherical equivalent correction. Testing consisted of high- and low-contrast visual acuity, contrast sensitivity, and reading acuity and speed using the Radner Reading Charts.Results: Thirty-eight of 40 subjects completed testing. Visual acuities at three contrast levels (100%, 25%, and 9% were significantly better using full correction than when using spherical equivalent correction (all P < 0.001. For contrast sensitivity testing under photopic, mesopic, and mesopic with glare conditions, only one out of twelve outcomes demonstrated a significant improvement with full correction compared with spherical equivalent correction (at six cycles per degree under mesopic without glare conditions, P = 0.046. Mean reading speed was numerically faster with full correction across all print sizes, reaching statistical significance at logarithm of the reading acuity determination (logRAD 0.2, 0.7, and 1.1 (P , 0.05. Statistically significant differences also favored full correction in logRAD score (P = 0.0376, corrected maximum reading speed (P < 0.001, and logarithm of the minimum angle of resolution/logRAD ratio (P < 0.001.Conclusions: In this study of pseudophakic subjects with low levels of postoperative astigmatism, full correction yielded significantly better reading performance and high- and low-contrast visual acuity than spherical equivalent correction, suggesting that cataractous patients may benefit from surgical

  9. Correction of low corneal astigmatism in cataract surgery

    Directory of Open Access Journals (Sweden)

    Pia Leon

    2015-08-01

    Full Text Available AIM: To evaluate and compare aspheric toric intraocular lens (IOL implantation and aspheric monofocal IOL implantation with limbal relaxing incisions (LRI to manage low corneal astigmatism (1.0-2.0 D in cataract surgery.METHODS:A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes (102 patients with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were:visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III (Nidek Co, Japan. Follow-up lasted 6mo.RESULTS: The mean uncorrected distance visual acuity (UCVA and the best corrected visual acuity (BCVA demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group (P<0.01. No difference was observed in the postoperative endothelial cell count between the two groups.CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

  10. Wavefront-Guided and Wavefront-Optimised Laser Treatments

    Directory of Open Access Journals (Sweden)

    Canan Aslı Utine

    2012-12-01

    Full Text Available Optical aberrations of the eye are the errors of the optical system that limit the resolution, contrast and amount of detail in the image formed on the retina. Wavefront technology allows us to measure these optical aberrations, calculate mathematically, and transfer this information into excimer laser system to perform customized treatment on the cornea. Two treatment algorithms developed to create low aberration-corneal profile are wavefront-optimised (WF-O and wavefront-guided (WF-G treatments. WF-O treatment, aims not to increase the existing spherical aberration while treatment is based on manifest refractive error as in conventional laser treatments. By increasing the number of laser spots applied peripherally in order to optimize the corneal asphericity, the preoperative central:peripheral keratometry ratio is preserved and optic zone shrinkage is prevented. On the other hand, WF-G treatment is based on aberrometry measurements and aims to correct the existing high-order aberrations in the eye. Thus, retinal image with high spatial details can be achieved. However, presence of postoperative defocus can abolish the successful results obtained with WF-G treatment. Clinical randomized controlled trials showed that in patients with preoperative RMS value of <0.3 μm, higher order aberration outcomes are similar after WF-G and WF-O treatments, but WF-G treatment yields better results when it is ≥0.4 μm. In normal eyes, very limited visual advantage can be achieved with WF-G treatment and preservation of asphericity value with WF-O treatment carries greater importance. On the other hand, in case of high astigmatism or higher order aberrations other than spherical aberration, decreasing aberrations with WF-G treatment becomes more important. In this study, we aimed to make a comparative analysis of characteristics and outcomes of the two treatment algorithms. (Turk J Ophthalmol 2012; 42: 474-8

  11. Torsional ultrasound mode versus combined torsional and conventional ultrasound mode phacoemulsification for eyes with hard cataract

    Directory of Open Access Journals (Sweden)

    Fakhry MA

    2011-07-01

    Full Text Available Mohamed A Fakhry1,2, Malak I El Shazly11Department of Ophthalmology, Kasr El Aini Hospital, Cairo University, Cairo, Egypt; 2Cataract and Refractive Consultant, International Eye Hospital, Cairo, EgyptPurpose: To compare torsional versus combined torsional and conventional ultrasound modes in hard cataract surgery regarding ultrasound energy and time and effect on corneal endothelium.Settings: Kasr El Aini hospital, Cairo University, and International Eye Hospital, Cairo, Egypt.Methodology: Ninety-eight eyes of 63 patients were enrolled in this prospective comparative randomized masked clinical study. All eyes had nuclear cataracts of grades III and IV using the Lens Opacities Classification System III (LOCS III. Two groups were included, each having an equal number of eyes (49. The treatment for group A was combined torsional and conventional US mode phacoemulsification, and for group B torsional US mode phacoemulsification only. Pre- and post-operative assessments included best corrected visual acuity (BCVA, intraocular pressure (IOP, slit-lamp evaluation, and fundoscopic evaluation. Endothelial cell density (ECD and central corneal thickness (CCT were measured preoperatively, 1 day, 7 days, and 1 month postoperatively. All eyes were operated on using the Alcon Infiniti System (Alcon, Fort Worth, TX with the quick chop technique. All eyes were implanted with AcrySof SA60AT (Alcon intraocular lens (IOL. The main phaco outcome parameters included the mean ultrasound time (UST, the mean cumulative dissipated energy (CDE, and the percent of average torsional amplitude in position 3 (%TUSiP3.Results: Improvement in BCVA was statistically significant in both groups (P < 0.001. Comparing UST and CDE for both groups revealed results favoring the pure torsional group (P = 0.002 and P < 0.001 for UST; P = 0.058 and P = 0.009 for CDE. As for %TUSiP3, readings were higher for the pure torsional group (P = 0.03 and P = 0.01. All changes of CCT, and ECD

  12. Intraoperative performance and postoperative outcomes of microcoaxial phacoemulsification. Observational study.

    Science.gov (United States)

    Vasavada, Viraj; Vasavada, Vaishali; Raj, Shetal M; Vasavada, Abhay R

    2007-06-01

    To evaluate the intraoperative performance and postoperative outcomes after microcoaxial phacoemulsification. Iladevi Cataract & IOL Research Centre, Ahmedabad, India. A prospective observational case series comprised 84 eyes with age-related uncomplicated cataract having microcoaxial phacoemulsification through a 2.2 mm clear corneal incision by a standard surgical technique. Phacoemulsification parameters (Infiniti Vision System, Alcon) were microburst width, 30 ms; preset power, 50%; vacuum, 650 mm Hg; aspiration flow rate, 25 cc/minute. A single-piece Alcon AcrySof intraocular lens was implanted with the C cartridge (Alcon) cartridge. The incision was measured at the end of surgery. Observations included surgical time (from commencement of sculpting to end of epinucleus removal), cumulative dissipated energy (CDE), wound burns, intraoperative complications, postoperative increase in mean central corneal thickness (CCT) at 1 day and 1 month, mean % decrease in endothelial cell density (ECD), absolute mean change in coefficient of variation (cv) 3 months, and uncorrected visual acuity (UCVA) at 1 day. Data were analyzed using a 1-sample t test with 95% confidence intervals (CIs). The mean follow up was 3 months +/- 0.3 (SD). The mean incision size at the end of surgery was 2.3 +/- .09 mm; mean surgical time, 4.5 +/- 1.5 minutes; and mean CDE, 2.3 +/- 2.2 seconds. No wound burns or other intraoperative complications occurred. The postoperative CCT increased by a mean of 16 microm at 1 day (95% CI, 8-25; P = .66;) and by a mean of 3.14 microm at 1 month (95% CI, 2.26-4.05; P = .92). The ECD decreased by a mean of 5.8% (95% CI, 6.8-3.5; P = .82) and the mean coefficient of variation, by 3.3 (95% CI, 4.5-2.0; P = .65). At 1 day, the UCVA was 20/20 in 29% of cases, 20/20 to 20/40 in 58%, and 20/40 to 20/50 in 12%. Microcoaxial phacoemulsification was safely and effectively performed, achieving consistent and satisfactory postoperative outcomes.

  13. Comparison of two optical biometers in intraocular lens power calculation

    Directory of Open Access Journals (Sweden)

    Sheng Hui

    2014-01-01

    Full Text Available Aims: To compare the consistency and accuracy in ocular biometric measurements and intraocular lens (IOL power calculations using the new optical low-coherence reflectometry and partial coherence interferometry. Subjects and Methods: The clinical data of 122 eyes of 72 cataract patients were analyzed retrospectively. All patients were measured with a new optical low-coherence reflectometry system, using the LENSTAR LS 900 (Haag Streit AG/ALLEGRO BioGraph biometer (Wavelight., AG, and partial coherence interferometry (IOLMaster V.5.4 [Carl Zeiss., Meditec, AG] before phacoemulsification and IOL implantation. Repeated measurements, as recommended by the manufacturers, were performed by the same examiner with both devices. Using the parameters of axial length (AL, corneal refractive power (K1 and K2, and anterior chamber depth (ACD, power calculations for AcrySof SA60AT IOL were compared between the two devices using five formulas. The target was emmetropia. Statistical analysis was performed using Statistical Package for the Social Sciences software (SPSS 13.0 with t-test as well as linear regression. A P value < 0.05 was considered to be statistically significant. Results: The mean age of 72 cataract patients was 64.6 years ± 13.4 [standard deviation]. Of the biometry parameters, K1, K2 and [K1 + K2]/2 values were significantly different between the two devices (mean difference, K1: −0.05 ± 0.21 D; K2: −0.12 ± 0.20 D; [K1 + K2]/2: −0.08 ± 0.14 D. P <0.05. There was no statistically significant difference in AL and ACD between the two devices. The correlations of AL, K1, K2, and ACD between the two devices were high. The mean differences in IOL power calculations using the five formulas were not statistically significant between the two devices. Conclusions: New optical low-coherence reflectometry provides measurements that correlate well to those of partial coherence interferometry, thus it is a precise device that can be used for the

  14. Visual Performance of a Quadrifocal (Trifocal) Intraocular Lens Following Removal of the Crystalline Lens.

    Science.gov (United States)

    Kohnen, Thomas; Herzog, Michael; Hemkeppler, Eva; Schönbrunn, Sabrina; De Lorenzo, Nina; Petermann, Kerstin; Böhm, Myriam

    2017-12-01

    To evaluate visual performance after implantation of a quadrifocal intraocular lens (IOL). Setting: Department of Ophthalmology, Goethe University, Frankfurt, Germany. Twenty-seven patients (54 eyes) received bilateral implantation of the PanOptix IOL (AcrySof IQ PanOptixTM; Alcon Research, Fort Worth, Texas, USA) pre-enrollment. Exclusion criteria were previous ocular surgeries, corneal astigmatism of >1.5 diopter (D), ocular pathologies, or corneal abnormalities. Intervention or Observational Procedure(s): Postoperative examination at 3 months including manifest refraction; uncorrected visual acuity (UCVA) and distance-corrected visual acuity (DCVA) in 4 m, 80 cm, 60 cm, and 40 cm slit-lamp examination; defocus testing; contrast sensitivity (CS) under photopic and mesopic conditions; and a questionnaire on subjective quality of vision, optical phenomena, and spectacle independence was performed. At 3 months postoperatively, UCVA and DCVA in 4 m, 80 cm, 60 cm, and 40 cm (logMAR), defocus curves, CS, and quality-of-vision questionnaire results. Mean spherical equivalent was -0.04 ± 0.321 D 3 months postoperatively. Binocular UCVA at distance, intermediate (80 cm, 60 cm), and near was 0.00 ± 0.094 logMAR, 0.09 ± 0.107 logMAR, 0.00 ± 0.111 logMAR, and 0.01 ± 0.087 logMAR, respectively. Binocular defocus curve showed peaks with best visual acuity (VA) at 0.00 D (-0.07 logMAR) and -2.00 D (-0.02 logMAR). Visual performance of the PanOptix IOL showed good VA at all distances; particularly good intermediate VA (logMAR > 0.1), with best VA at 60 cm; and high patient satisfaction and spectacle independence 3 months postoperatively. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Corneal Endothelial Safety of Intracameral Preservative-free 1% Xylocaine

    Directory of Open Access Journals (Sweden)

    Shah Alpesh

    2004-01-01

    Full Text Available Purpose : To evaluate the effect of intracameral preservative-free 1% xylocaine on the corneal endothelium as an adjuvant to topical anaesthesia during phacoemulsification and Acrysof foldable IOL implantation. Material & Methods: This is a prospective, controlled, randomised, double-masked study. 106 patients with soft to moderately dense (Grade 1-3 senile cataract and corneal endothelial cell density of >1500/mm2 were randomised to the xylocaine group (n=53 and control group(n=53. Central endothelial specular microscopy and ultrasound corneal pachymetry were performed preoperatively. On the first postoperative day the eyes were evaluated for corneal oedema and Descemet′s folds. Ultrasound corneal pachymetry was performed at 1, 3 and 12 months. Specular microscopy was performed at 3 and 12 months. Cell loss was expressed as a percentage of preoperative cell density. Six patients could not complete one year follow-up. Chi-square and paired t test (2 tail statistical tests were applied for analysis. Results: Four (7.54% patients in the xylocaine group and 5 (9.43% in the control group had a few Descemet′s folds associated with mild central stromal oedema. Corneal thickness increased from 549.3µ ± 37.2µ to 555.5µ ± 36.5µ in the xylocaine group and from 553.1µ ± 36.2µ to 559.3µ ± 40.5µ in the control group at the one-month postoperative visit. Thickness returned to the preoperative level in xylocaine group 549.6µ ± 34.5µ and control group 554.7µ ± 41.1µ at three months. (P=0.484 The percentage of cell loss was 4.47 ± 2.53% in the xylocaine group and 4.49 ± 3.09 % in the control group at one year. (P=0.97 Conclusion: Intracameral preservative-free 1% xylocaine does not appear to affect corneal endothelium adversely during phacoemulsification.

  16. An angle-supported foldable phakic intraocular lens for correction of myopia: A five-year follow-up.

    Science.gov (United States)

    Alió, J L; Plaza-Puche, A B; Cavas, F; Yébana Rubio, P; Sala, E

    2017-01-01

    To evaluate the efficacy and safety of an angle-supported foldable phakic intraocular lens (pIOL) for the correction of moderate to high myopia after 5 years follow-up. Prospective and retrospective, observational, longitudinal, non-randomised consecutive series of cases conducted on a total of 100 eyes of 67 patients with moderate to high myopia implanted with an Acrysof Cachet pIOL (Alcon Laboratories Inc.) with the aim of minimising the refractive error. The ages ranged between 18 to 60years. Uncorrected distance visual acuity (UDVA), manifest refraction, corrected distance visual acuity (CDVA), endothelial cells density, pIOL position, intraocular pressure, and complications were recorded preoperatively and during the 5 year follow-up. Five years after implantation, the mean manifest spherical equivalent refraction reduced significantly from -11.62±3.35 dioptres (D) to -0.33±0.85D. UDVA was 20/20 or better in 5 of 25 cases (20%), and 20/40 or better in 22 cases (88%). CDVA was 20/20 or better in 17 cases (68%), and 20/32 or better in 23 cases (92%) of eyes. The residual refractive error was within ±0.50D of emmetropia in 12 cases (48%), and within ±1.00D in 19 cases (76%). Mean endothelial cell loss at 5 years was 11.8% central, and 13.7% peripheral. Mean endothelium-pIOL distance was 2.11±0.18mm, and mean pIOL-crystalline distance was 0.88±0.20mm. This angle supported pIOL provided a favourable refractive correction and predictability, as well as acceptable safety in patients with moderate to high myopia. Although endothelial cell density decreased over 5years, the results are within the range reported in previous studies with other pIOLs. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Phacoemulsification in subluxated cataract.

    Directory of Open Access Journals (Sweden)

    Praveen M

    2003-01-01

    Full Text Available Purpose: To evaluate the outcome of phacoemulsification in eyes with subluxated cataract. Materials and Methods: This retrospective study comprised 22 eyes of 20 consecutive patients with subluxated cataracts of varying aetiology operated between March 1998 and March 2001. Detailed preoperative assessment included visual acuity (VA, slitlamp examination, presence of vitreous in anterior chamber, extent of subluxation, intraocular pressure (IOP and detailed fundus examination. Phacoemulsification was done to retain the natural bag support and all patients had acrylic foldable Acrysof IOL implantation either in-the-bag or by scleral fixation. Postoperative observations included best-corrected visual acuity (BCVA, IOP, pupillary reaction and the IOL position. Results: The aetiology of the subluxation was traumatic in 11 patients and non-traumatic in 9 patients. Fifteen were males and 5 were females. Mean follow-up was 11.7 ± 9.71 months (range 4-39. The average age was 39.15 ± 16.33 (range 5 - 74. A 2-port anterior chamber vitrectomy was performed in 6 eyes (27.2%. Capsule tension ring (CTR was implanted in 15 eyes (68.18%. Twelve eyes (54.5% had in-the-bag implants, while 5 (22.72% had scleral fixation. The remaining 5 eyes (22.72% had one haptic in-the-bag and another sutured to sclera. No major intraoperative complications were noted. Twelve eyes (54.5% had clinically and geometrically well centered IOLs while 9 eyes (40.9% had geometrically decentered IOLs. One patient was lost to follow-up. Fifteen eyes (55.55% had postoperative BCVA of 6/12 - 6/6 while 2 eyes (7.40% had BCVA of 6/18. The remaining 4 eyes (14.81% had less than 6/24 BCVA due to pre-existing posterior segment pathology. Postoperative complications included rise in IOP in 1 eye (4.54%, pupillary capture of the IOL optic in 2 eyes (9.09%; the same 2 eyes (9.09% required redialing of IOL. One eye (4.54% had to undergo refixation (one haptic was fixed to sclera year after cataract

  18. Probing the accuracy and precision of Hirshfeld atom refinement with HARt interfaced with Olex2

    Directory of Open Access Journals (Sweden)

    Malte Fugel

    2018-01-01

    Full Text Available Hirshfeld atom refinement (HAR is a novel X-ray structure refinement technique that employs aspherical atomic scattering factors obtained from stockholder partitioning of a theoretically determined tailor-made static electron density. HAR overcomes many of the known limitations of independent atom modelling (IAM, such as too short element–hydrogen distances, r(X—H, or too large atomic displacement parameters (ADPs. This study probes the accuracy and precision of anisotropic hydrogen and non-hydrogen ADPs and of r(X—H values obtained from HAR. These quantities are compared and found to agree with those obtained from (i accurate neutron diffraction data measured at the same temperatures as the X-ray data and (ii multipole modelling (MM, an established alternative method for interpreting X-ray diffraction data with the help of aspherical atomic scattering factors. Results are presented for three chemically different systems: the aromatic hydrocarbon rubrene (orthorhombic 5,6,11,12-tetraphenyltetracene, a co-crystal of zwitterionic betaine, imidazolium cations and picrate anions (BIPa, and the salt potassium hydrogen oxalate (KHOx. The non-hydrogen HAR-ADPs are as accurate and precise as the MM-ADPs. Both show excellent agreement with the neutron-based values and are superior to IAM-ADPs. The anisotropic hydrogen HAR-ADPs show a somewhat larger deviation from neutron-based values than the hydrogen SHADE-ADPs used in MM. Element–hydrogen bond lengths from HAR are in excellent agreement with those obtained from neutron diffraction experiments, although they are somewhat less precise. The residual density contour maps after HAR show fewer features than those after MM. Calculating the static electron density with the def2-TZVP basis set instead of the simpler def2-SVP one does not improve the refinement results significantly. All HARs were performed within the recently introduced HARt option implemented in the Olex2 program. They are easily

  19. Aplanatic telescopes based on Schwarzschild optical configuration: from grazing incidence Wolter-like x-ray optics to Cherenkov two-mirror normal incidence telescopes

    Science.gov (United States)

    Sironi, Giorgia

    2017-09-01

    At the beginning of XX century Karl Schwarzschild defined a method to design large-field aplanatic telescopes based on the use of two aspheric mirrors. The approach was then refined by Couder (1926) who, in order to correct for the astigmatic aberration, introduced a curvature of the focal plane. By the way, the realization of normal-incidence telescopes implementing the Schwarzschild aplanatic configuration has been historically limited by the lack of technological solutions to manufacture and test aspheric mirrors. On the other hand, the Schwarzschild solution was recovered for the realization of coma-free X-ray grazing incidence optics. Wolter-like grazing incidence systems are indeed free of spherical aberration, but still suffer from coma and higher order aberrations degrading the imaging capability for off-axis sources. The application of the Schwarzschild's solution to X-ray optics allowed Wolter to define an optical system that exactly obeys the Abbe sine condition, eliminating coma completely. Therefore these systems are named Wolter-Schwarzschild telescopes and have been used to implement wide-field X-ray telescopes like the ROSAT WFC and the SOHO X-ray telescope. Starting from this approach, a new class of X-ray optical system was proposed by Burrows, Burg and Giacconi assuming polynomials numerically optimized to get a flat field of view response and applied by Conconi to the wide field x-ray telescope (WFXT) design. The Schwarzschild-Couder solution has been recently re-discovered for the application to normal-incidence Cherenkov telescopes, thanks to the suggestion by Vassiliev and collaborators. The Italian Institute for Astrophysics (INAF) realized the first Cherenkov telescope based on the polynomial variation of the Schwarzschild configuration (the so-called ASTRI telescope). Its optical qualification was successfully completed in 2016, demonstrating the suitability of the Schwarzschild-like configuration for the Cherenkov astronomy requirements

  20. Lidar measurements of boundary layer depolarization and CCSEM-EDX compositional analysis of airborne particles on collocated passive samplers throughout the forest canopy during the 2016 airborne pollen season at UMBS, Pellston, MI

    Science.gov (United States)

    Wozniak, M. C.; Steiner, A.; Ault, A. P.; Kort, E. A.; Lersch, T.; Casuccio, G.

    2017-12-01

    Observations of airborne pollen are typically made with volumetric samplers that obtain a time-averaged pollen concentration at a single point. While spatial variations in surface pollen concentrations may be known with these samplers given multiple sampling sites, real-time boundary layer transport of pollen grains cannot be determined except by particle dispersion or tracer transport models. Recently, light detection and ranging (lidar) techniques, such as depolarization, have been used to measure pollen transport and optical properties throughout the boundary layer over time. Here, we use a ground-based micro-pulse lidar (MPL) to observe boundary layer vertical profiles before, during and after the peak anemophilous (wind-driven) pollen season. The lidar depolarization ratio is measured in tandem with the normalized R-squared backscatter (NRB) intensity to determine the contribution of aspherical particles to the scatterers present throughout the boundary layer. Measurements are taken from April 15 - July 12, 2016 at the University of Michigan Biological Station (UMBS) PROPHET outdoor research lab and tower within a largely forested region. UMBS is dominated by Acer rubrum, Betula papyrifera, Pinus resinosa, Quercus rubra and Pinus strobus, all of which began flowering on 4/19, 5/3, 5/25, 5/25 and 6/14, respectively. Temperature, relative humidity and wind speed measured on site determine daytime conditions conducive to pollen dispersion from flowers. Lidar depolarization ratios between 0.08-0.14 and higher are observed in the daytime boundary layer on days shortly after the flowering dates of the aforementioned species, elevated above the background level of 0.06 or less. Lidar observations are supplemented with aerosol compositional analysis determined by computer-controlled scanning electron microscopy and energy-dispersive X-ray spectroscopy (CCSEM-EDX) on passive sampler data from below, within and above the forest canopy at PROPHET tower. Particles are

  1. Every photon counts: improving low, mid, and high-spatial frequency errors on astronomical optics and materials with MRF

    Science.gov (United States)

    Maloney, Chris; Lormeau, Jean Pierre; Dumas, Paul

    2016-07-01

    Many astronomical sensing applications operate in low-light conditions; for these applications every photon counts. Controlling mid-spatial frequencies and surface roughness on astronomical optics are critical for mitigating scattering effects such as flare and energy loss. By improving these two frequency regimes higher contrast images can be collected with improved efficiency. Classically, Magnetorheological Finishing (MRF) has offered an optical fabrication technique to correct low order errors as well has quilting/print-through errors left over in light-weighted optics from conventional polishing techniques. MRF is a deterministic, sub-aperture polishing process that has been used to improve figure on an ever expanding assortment of optical geometries, such as planos, spheres, on and off axis aspheres, primary mirrors and freeform optics. Precision optics are routinely manufactured by this technology with sizes ranging from 5-2,000mm in diameter. MRF can be used for form corrections; turning a sphere into an asphere or free form, but more commonly for figure corrections achieving figure errors as low as 1nm RMS while using careful metrology setups. Recent advancements in MRF technology have improved the polishing performance expected for astronomical optics in low, mid and high spatial frequency regimes. Deterministic figure correction with MRF is compatible with most materials, including some recent examples on Silicon Carbide and RSA905 Aluminum. MRF also has the ability to produce `perfectly-bad' compensating surfaces, which may be used to compensate for measured or modeled optical deformation from sources such as gravity or mounting. In addition, recent advances in MRF technology allow for corrections of mid-spatial wavelengths as small as 1mm simultaneously with form error correction. Efficient midspatial frequency corrections make use of optimized process conditions including raster polishing in combination with a small tool size. Furthermore, a novel MRF

  2. Probing the accuracy and precision of Hirshfeld atom refinement with HARt interfaced with Olex2.

    Science.gov (United States)

    Fugel, Malte; Jayatilaka, Dylan; Hupf, Emanuel; Overgaard, Jacob; Hathwar, Venkatesha R; Macchi, Piero; Turner, Michael J; Howard, Judith A K; Dolomanov, Oleg V; Puschmann, Horst; Iversen, Bo B; Bürgi, Hans-Beat; Grabowsky, Simon

    2018-01-01

    Hirshfeld atom refinement (HAR) is a novel X-ray structure refinement technique that employs aspherical atomic scattering factors obtained from stockholder partitioning of a theoretically determined tailor-made static electron density. HAR overcomes many of the known limitations of independent atom modelling (IAM), such as too short element-hydrogen distances, r ( X -H), or too large atomic displacement parameters (ADPs). This study probes the accuracy and precision of anisotropic hydrogen and non-hydrogen ADPs and of r ( X -H) values obtained from HAR. These quantities are compared and found to agree with those obtained from (i) accurate neutron diffraction data measured at the same temperatures as the X-ray data and (ii) multipole modelling (MM), an established alternative method for interpreting X-ray diffraction data with the help of aspherical atomic scattering factors. Results are presented for three chemically different systems: the aromatic hydro-carbon rubrene (orthorhombic 5,6,11,12-tetra-phenyl-tetracene), a co-crystal of zwitterionic betaine, imidazolium cations and picrate anions (BIPa), and the salt potassium hydrogen oxalate (KHOx). The non-hydrogen HAR-ADPs are as accurate and precise as the MM-ADPs. Both show excellent agreement with the neutron-based values and are superior to IAM-ADPs. The anisotropic hydrogen HAR-ADPs show a somewhat larger deviation from neutron-based values than the hydrogen SHADE-ADPs used in MM. Element-hydrogen bond lengths from HAR are in excellent agreement with those obtained from neutron diffraction experiments, although they are somewhat less precise. The residual density contour maps after HAR show fewer features than those after MM. Calculating the static electron density with the def2-TZVP basis set instead of the simpler def2-SVP one does not improve the refinement results significantly. All HARs were performed within the recently introduced HARt option implemented in the Olex2 program. They are easily launched

  3. [Halos and multifocal intraocular lenses: origin and interpretation].

    Science.gov (United States)

    Alba-Bueno, F; Vega, F; Millán, M S

    2014-10-01

    To present the theoretical and experimental characterization of the halo in multifocal intraocular lenses (MIOL). The origin of the halo in a MIOL is the overlaying of 2 or more images. Using geometrical optics, it can be demonstrated that the diameter of each halo depends on the addition of the lens (ΔP), the base power (P(d)), and the diameter of the IOL that contributes to the «non-focused» focus. In the image plane that corresponds to the distance focus, the halo diameter (δH(d)) is given by: δH(d)=d(pn) ΔP/P(d), where d(pn) is the diameter of the IOL that contributes to the near focus. Analogously, in the near image plane the halo diameter (δH(n)) is: δH(n)=d(pd) ΔP/P(d), where d(pd) is the diameter of the IOL that contributes to the distance focus. Patients perceive halos when they see bright objects over a relatively dark background. In vitro, the halo can be characterized by analyzing the intensity profile of the image of a pinhole that is focused by each of the foci of a MIOL. A comparison has been made between the halos induced by different MIOL of the same base power (20D) in an optical bench. As predicted by theory, the larger the addition of the MIOL, the larger the halo diameter. For large pupils and with MIOL with similar aspheric designs and addition (SN6AD3 vs ZMA00), the apodized MIOL has a smaller halo diameter than a non-apodized one in distance vision, while in near vision the size is very similar, but the relative intensity is higher in the apodized MIOL. When comparing lenses with the same diffractive design, but with different spherical-aspheric base design (SN60D3 vs SN6AD3), the halo in distance vision of the spherical MIOL is larger, while in near vision the spherical IOL induces a smaller halo, but with higher intensity due to the spherical aberration of the distance focus in the near image. In the case of a trifocal-diffractive IOL (AT LISA 839MP) the most noticeable characteristic is the double-halo formation due to the 2 non

  4. Classification of Arctic, Mid-Latitude and Tropical Clouds in the Mixed-Phase Temperature Regime

    Science.gov (United States)

    Costa, Anja; Afchine, Armin; Luebke, Anna; Meyer, Jessica; Dorsey, James R.; Gallagher, Martin W.; Ehrlich, André; Wendisch, Manfred; Krämer, Martina

    2016-04-01

    The degree of glaciation and the sizes and habits of ice particles formed in mixed-phase clouds remain not fully understood. However, these properties define the mixed clouds' radiative impact on the Earth's climate and thus a correct representation of this cloud type in global climate models is of importance for an improved certainty of climate predictions. This study focuses on the occurrence and characteristics of two types of clouds in the mixed-phase temperature regime (238-275K): coexistence clouds (Coex), in which both liquid drops and ice crystals exist, and fully glaciated clouds that develop in the Wegener-Bergeron-Findeisen regime (WBF clouds). We present an extensive dataset obtained by the Cloud and Aerosol Particle Spectrometer NIXE-CAPS, covering Arctic, mid-latitude and tropical regions. In total, we spent 45.2 hours within clouds in the mixed-phase temperature regime during five field campaigns (Arctic: VERDI, 2012 and RACEPAC, 2014 - Northern Canada; mid-latitude: COALESC, 2011 - UK and ML-Cirrus, 2014 - central Europe; tropics: ACRIDICON, 2014 - Brazil). We show that WBF and Coex clouds can be identified via cloud particle size distributions. The classified datasets are used to analyse temperature dependences of both cloud types as well as range and frequencies of cloud particle concentrations and sizes. One result is that Coex clouds containing supercooled liquid drops are found down to temperatures of -40 deg C only in tropical mixed clouds, while in the Arctic and mid-latitudes no liquid drops are observed below about -20 deg C. In addition, we show that the cloud particles' aspherical fractions - derived from polarization signatures of particles with diameters between 20 and 50 micrometers - differ significantly between WBF and Coex clouds. In Coex clouds, the aspherical fraction of cloud particles is generally very low, but increases with decreasing temperature. In WBF clouds, where all cloud particles are ice, about 20-40% of the cloud

  5. Imaging X-Ray Polarimetry Explorer Mission Attitude Determination and Control Concept

    Science.gov (United States)

    Bladt, Jeff; Deininger, William D.; Kalinowski, William C.; Boysen, Mary; Bygott, Kyle; Guy, Larry; Pentz, Christina; Seckar, Chris; Valdez, John; Wedmore, Jeffrey; hide

    2018-01-01

    The goal of the Imaging X-Ray Polarimetry Explorer (IXPE) Mission is to expand understanding of high-energy astrophysical processes and sources, in support of NASA's first science objective in Astrophysics: "Discover how the universe works." X-ray polarimetry is the focus of the IXPE science mission. Polarimetry uniquely probes physical anisotropies-ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin-that are not otherwise measurable. The IXPE Observatory consists of Spacecraft and Payload modules. The Payload includes three polarization sensitive, X-ray detector units (DU), each paired with its corresponding grazing incidence mirror module assemblies (MMA). A deployable boom provides the correct separation (focal length) between the DUs and MMAs. These Payload elements are supported by the IXPE Spacecraft. A star tracker is mounted directly with the deployed Payload to minimize alignment errors between the star tracker line of sight (LoS) and Payload LoS. Stringent pointing requirements coupled with a flexible structure and a non-collocated attitude sensor-actuator configuration requires a thorough analysis of control-structure interactions. A non-minimum phase notch filter supports robust control loop stability margins. This paper summarizes the IXPE mission science objectives and Observatory concepts, and then it describes IXPE attitude determination and control implementation. IXPE LoS pointing accuracy, control loop stability, and angular momentum management are discussed.

  6. The spatial distribution of C2, C3, and NH in comet 2P/Encke

    International Nuclear Information System (INIS)

    Dorman, Garrett; Pierce, Donna M.; Cochran, Anita L.

    2013-01-01

    We examine the spatial distribution of C 2 , C 3 , and NH radicals in the coma of comet Encke in order to understand their abundances and distributions in the coma. The observations were obtained from 2003 October 22-24, using the 2.7 m telescope at McDonald Observatory. Building on our original study of CN and OH, we have used our modified version of the vectorial model, which treats the coma as one large cone, in order to reproduce Encke's highly aspherical and asymmetric coma. Our results suggest that NH can be explained by the photodissociation of NH 2 , assuming that NH 2 is produced rapidly from NH 3 in the innermost coma. Our modeling of C 2 and C 3 suggests a multi-generational photodissociation process may be required for their production. Using the results of our previous study, we also obtain abundance ratios with respect to OH and CN. Overall, we find that Encke exhibits typical carbon-chain abundances, and the results are consistent with other studies of comet Encke.

  7. Jamming of soft particles: geometry, mechanics, scaling and isostaticity

    International Nuclear Information System (INIS)

    Van Hecke, M

    2010-01-01

    Amorphous materials as diverse as foams, emulsions, colloidal suspensions and granular media can jam into a rigid, disordered state where they withstand finite shear stresses before yielding. Here we review the current understanding of the transition to jamming and the nature of the jammed state for disordered packings of particles that act through repulsive contact interactions and are at zero temperature and zero shear stress. We first discuss the breakdown of affine assumptions that underlies the rich mechanics near jamming. We then extensively discuss jamming of frictionless soft spheres. At the jamming point, these systems are marginally stable (isostatic) in the sense of constraint counting, and many geometric and mechanical properties scale with distance to this jamming point. Finally, we discuss current explorations of jamming of frictional and non-spherical (ellipsoidal) particles. Both friction and asphericity tune the contact number at jamming away from the isostatic limit, but in opposite directions. This allows one to disentangle the distance to jamming and the distance to isostaticity. The picture that emerges is that most quantities are governed by the contact number and scale with the distance to isostaticity, while the contact number itself scales with the distance to jamming. (topical review)

  8. Some answers to new challenges in optical metrology

    Science.gov (United States)

    Osten, W.

    2008-09-01

    The visible trend in the implementation of new technologies and creation of new products is the continuous reduction of feature sizes. However, in the same way as the feature sizes are decreasing, the theoretical and practical constraints of making them and ensuring their quality are increasing. Consequently, modern production and inspection technologies are confronted with a bundle of challenges. An important barrier for optical imaging and sensing is the diffraction limited lateral resolution. The observation of this physical limitation is of increasing importance, not only for microscopic techniques but also for the application of 3D-measurement techniques on wafer scale level. A further challenge is the reliable detection of imperfections and material faults within the production chain. This means in-line metrology/defectoscopy is a must for future production systems. Only the real-time feedback of the inspection results into the production process can contribute to a consistent quality assurance in processes with high cost risk. Moreover the reliable measurement of free form surfaces, both technical and optical, the assurance of the traceability and the certified assessment of the uncertainty of the measurement results are ongoing challenges. The challenges and the physical limitations are addressed here by new approaches for testing semiconductor structures with enhanced resolution, the measurement of aspheric lenses with increased flexibility and the inspection of micro components with improved traceability.

  9. The new null testing method for the special optical window

    Science.gov (United States)

    Huang, Changchun

    2009-07-01

    The high speed, high precision and wide range specifications are requirement for the modern aircraft, which the traditional hemispherical dome can't achieve now, and the novel conformal window instead can enhance the aerodynamic performance of the aircraft obviously. To reduce the aerodynamic drag and radar cross-section, the window geometry is generally aspheric in shape. As a result, the involved fabrication and testing processes are much more challenging than that of conventional optics and must be mastered before these windows and systems can be implemented at an acceptable cost and risk. Metrology is one of the critical areas required to advance the conformal window technology. But as the surface of these conformal windows is not the traditional sphere lens, the measurement method for it is infeasible with the conventional optics measurement processes. This paper we express the development of testing technology for the special conformal windows in brief, and emphatically introduces one available novel testing method- a new null testing, and here based on the theory of compensation methods, The principle of Offner's refractive null lens has been extended to test the transmission wavefront through conformal window optics and provide feedback during surface fabrication. a compensator system for the was designed for the conformal window is given which parameters are 100mm for its aperture and two parabolic surface as conformal window, the final residual wavefront error(RMS) of which is less than 1/20λ(λ=632.8nm).

  10. Advanced laser-backlit grazing-incidence x-ray imaging systems for inertial confinement fusion research. II. Tolerance analysis

    International Nuclear Information System (INIS)

    Bennett, Guy R.; Folta, James A.

    2001-01-01

    Two example ultrahigh-spatial resolution laser-backlit grazing-incidence x-ray microscope designs for inertial confinement fusion (ICF) research have been described [Appl. Opt. 40, 4570 (2001)]. Here details of fabrication, assembly, and optical surface errors that are characteristic of present state-of-the-art superpolished multilayer-coated spherical mirrors are given. They indicate that good image qualities can be expected; in particular, <0.5-μm spatial resolution at very high x-ray energies (up to 25 keV) appears to be feasible. Existing ICF imaging diagnostics approach ∼2 μm spatial at low (<2 keV) energy. The improvement in resolution compared with that of other grazing-incidence devices is attributed to a fortuitous residual on-axis aberration dependence on short wavelengths; recent advances in mirror fabrication, including a new thin-film deposition technique to correct figure errors precisely in one dimension; and novel design. For even higher resolution, a means of creating precise aspherical mirrors of spheric-quality microroughness may be possible by use of the same deposition technique

  11. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function.

    Science.gov (United States)

    Servin, Manuel; Padilla, Moises; Garnica, Guillermo

    2016-05-02

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength (DW) PSA is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesis herein presented may be used for interferometric contouring of discontinuous industrial objects. Also DW-PSA may be useful for DW shop-testing of deep free-form aspheres. As shown here, using the FTF-based synthesis one may easily find explicit DW-PSA formulae optimized for high signal-to-noise and high detuning robustness. To this date, no general synthesis and analysis for temporal DW-PSAs has been given; only ad hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae for their spectra, their signal-to-noise, their detuning and harmonic robustness has been given. Here for the first time a fully general procedure for designing DW-PSAs (or triple-wavelengths PSAs) with desire spectrum, signal-to-noise ratio and detuning robustness is given. We finally generalize DW-PSA to higher number of wavelength temporal PSAs.

  12. Four-manifolds, geometries and knots

    CERN Document Server

    Hillman, Jonathan A

    2007-01-01

    The goal of this book is to characterize algebraically the closed 4-manifolds that fibre nontrivially or admit geometries in the sense of Thurston, or which are obtained by surgery on 2-knots, and to provide a reference for the topology of such manifolds and knots. The first chapter is purely algebraic. The rest of the book may be divided into three parts: general results on homotopy and surgery (Chapters 2-6), geometries and geometric decompositions (Chapters 7-13), and 2-knots (Chapters 14-18). In many cases the Euler characteristic, fundamental group and Stiefel-Whitney classes together form a complete system of invariants for the homotopy type of such manifolds, and the possible values of the invariants can be described explicitly. The strongest results are characterizations of manifolds which fibre homotopically over S^1 or an aspherical surface (up to homotopy equivalence) and infrasolvmanifolds (up to homeomorphism). As a consequence 2-knots whose groups are poly-Z are determined up to Gluck reconstruc...

  13. Mobile Laser Indirect Ophthalmoscope: For the Induction of Choroidal Neovascularization in a Mouse Model.

    Science.gov (United States)

    Weinberger, Dov; Bor-Shavit, Elite; Barliya, Tilda; Dahbash, Mor; Kinrot, Opher; Gaton, Dan D; Nisgav, Yael; Livnat, Tami

    2017-11-01

    This study aims to evaluate and standardize the reliability of a mobile laser indirect ophthalmoscope in the induction of choroidal neovascularization (CNV) in a mouse model. A diode laser indirect ophthalmoscope was used to induce CNV in pigmented male C57BL/6J mice. Standardization of spot size and laser intensity was determined using different aspheric lenses with increasing laser intensities applied around the optic disc. Development of CNV was evaluated 1, 5, and 14 days post laser application using fluorescein angiography (FA), histology, and choroidal flat mounts stained for the endothelial marker CD31 and FITC-dextran. Correlation between the number of laser hits to the number and size of developed CNV lesions was determined using flat mount choroid staining. The ability of intravitreally injected anti-human and anti-mouse VEGF antibodies to inhibit CNV induced by the mobile laser was evaluated. Laser parameters were standardized on 350 mW for 100 msec, using the 90 diopter lens to accomplish the highest incidence of Bruch's membrane rupture. CNV lesions' formation was validated on days 5 and 14 post laser injury, though FA showed leakage on as early as day 1. The number of laser hits was significantly correlated with the CNV area. CNV growth was successfully inhibited by both anti-human and mouse VEGF antibodies. The mobile laser indirect ophthalmoscope can serve as a feasible and a reliable alternative method for the CNV induction in a mouse model.

  14. Robotic Automation in Computer Controlled Polishing

    Science.gov (United States)

    Walker, D. D.; Yu, G.; Bibby, M.; Dunn, C.; Li, H.; Wu, Y.; Zheng, X.; Zhang, P.

    2016-02-01

    We first present a Case Study - the manufacture of 1.4 m prototype mirror-segments for the European Extremely Large Telescope, undertaken by the National Facility for Ultra Precision Surfaces, at the OpTIC facility operated by Glyndwr University. Scale-up to serial-manufacture demands delivery of a 1.4 m off-axis aspheric hexagonal segment with surface precision robots and computer numerically controlled ('CNC') polishing machines for optical fabrication. The objective was not to assess which is superior. Rather, it was to understand for the first time their complementary properties, leading us to operate them together as a unit, integrated in hardware and software. Three key areas are reported. First is the novel use of robots to automate currently-manual operations on CNC polishing machines, to improve work-throughput, mitigate risk of damage to parts, and reduce dependence on highly-skilled staff. Second is the use of robots to pre-process surfaces prior to CNC polishing, to reduce total process time. The third draws the threads together, describing our vision of the automated manufacturing cell, where the operator interacts at cell rather than machine level. This promises to deliver a step-change in end-to-end manufacturing times and costs, compared with either platform used on its own or, indeed, the state-of-the-art used elsewhere.

  15. Noctilucent clouds in the polar sumer mesopause: Investigations using the ALOMAR Rayleigh/Mie/Raman Lidar; Leuchtende Nachtwolken an der polaren Sommermesopause: Untersuchungen mit dem ALOMAR Rayleigh/Mie/Raman Lidar

    Energy Technology Data Exchange (ETDEWEB)

    Baumgarten, G.

    2001-09-01

    Noctilucent clouds (NLC) are rare, tenuous clouds in the terrestrial atmosphere that occur at polar latitudes in summer near 83 km altitude. These clouds where studied using the ALOMAR Rayleigh/Mie/Raman lidar located at 69 N, 16 E. The depolarization of light, which was backscattered on NLC particles was measured for the first time by the ALOMAR RMR-Lidar. Considering the small ratio of particle size over wavelength an unexpectedly large depolarization of 1.7% was observed. Comparing this result to T-matrix calculations for scattering on randomly oriented aspherical particles implies that the shape of the NLC particles is needle like. The ALOMAR RMR-Lidar is a twin-lidar equipped with two steerable telescopes which were used to observe a single NLC layer in two separate measurement volumes about 50 km apart at NLC altitudes. Cross correlation technique reveal the layer to be tilted with imbedded periodic horizontal structures showing wavelengths of about 30 to 50 km. These structures drift horizontally through the measurement volumes rather than being microphysically formed during the observation period. (orig.)

  16. SPECTROPOLARIMETRY OF SUPERLUMINOUS SUPERNOVAE: INSIGHT INTO THEIR GEOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Inserra, C.; Bulla, M.; Sim, S. A.; Smartt, S. J., E-mail: c.inserra@qub.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom)

    2016-11-01

    We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova (SLSN) at z = 0.1136, namely SN 2015bn. The transient shows significant polarization at both of the observed epochs: one 24 days before maximum light in the rest-frame, and the other at 27 days after peak luminosity. Analysis of the Q – U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoch. We use a Monte Carlo code to demonstrate that these properties are consistent with a simple toy model that adopts an axisymmetric ellipsoidal configuration for the ejecta. We find that the wavelength dependence of the polarization is possibly due to a strong wavelength dependence in the line opacity, while the higher level of polarization at the second epoch is a consequence of the increase in the asphericity of the inner layers of the ejecta or the fact that the photosphere recedes into less spherical layers. The geometry of the SLSN is similar to that of stripped-envelope core-collapse SNe connected to GRB, while the overall evolution of the ejecta shape could be consistent with a central engine.

  17. Blended learning is an effective strategy for acquiring competence in public health biostatistics.

    Science.gov (United States)

    Milic, Natasa; Masic, Srdjan; Bjegovic-Mikanovic, Vesna; Trajkovic, Goran; Marinkovic, Jelena; Milin-Lazovic, Jelena; Bukumiric, Zoran; Savic, Marko; Cirkovic, Andja; Gajic, Milan; Stanisavljevic, Dejana

    2018-04-01

    We sought to determine whether blended learning is an effective strategy for acquiring competence in public health biostatistics. The trial was conducted with 69 Masters' students of public health attending the School of Public Health at University of Belgrade. Students were exposed to the traditional and blended learning styles. Blended learning included a combination of face-to-face and distance learning methodologies integrated into a single course. Curriculum development was guided by competencies as suggested by the Association of Schools of Public Health in the European Region (ASPHER). Teaching methods were compared according to the final competence score. Forty-four students were enrolled in the traditional method of education delivery, and 25 to the blended learning format. Mean exam scores for the blended learning group were higher than for the on-site group for both the final statistics score (89.65 ± 6.93 vs. 78.21 ± 13.26; p  0.8). A blended learning approach is an attractive and effective way of acquiring biostatistics competence for Masters of Public Health (MPH) graduate students.

  18. Improving solar-pumped laser efficiency by a ring-array concentrator

    Science.gov (United States)

    Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.

    2018-01-01

    We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.

  19. Formation and internal structure of superdense dark matter clumps and ultracompact minihaloes

    Energy Technology Data Exchange (ETDEWEB)

    Berezinsky, V.S. [INFN, Laboratori Nazionali del Gran Sasso, Center for Astroparticle Physics at LNGS (CFA), I-67010 Assergi (AQ) (Italy); Dokuchaev, V.I.; Eroshenko, Yu.N., E-mail: berezinsky@lngs.infn.it, E-mail: dokuchaev@lngs.infn.it, E-mail: eroshenko@inr.ac.ru [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect 7a, 117312 Moscow (Russian Federation)

    2013-11-01

    We discuss the formation mechanisms and structure of the superdense dark matter clumps (SDMC) and ultracompact minihaloes (UCMH), outlining the differences between these types of DM objects. We define as SDMC the gravitationally bounded DM objects which have come into virial equilibrium at the radiation-dominated (RD) stage of the universe evolution. Such objects can be formed from the isocurvature (entropy) density perturbations or from the peaks in the spectrum of curvature (adiabatic) perturbation. The axion miniclusters (Kolb and Tkachev 1994) are the example of the former model. The system of central compact mass (e.g. in the form of SDMC or primordial black hole (PBH)) with the outer DM envelope formed in the process of secondary accretion we refer to as UCMH. Therefore, the SDMC can serve as the seed for the UCMH in some scenarios. Recently, the SDMC and UCMH were considered in the many works, and we try to systematize them here. We consider also the effect of asphericity of the initial density perturbation in the gravitational evolution, which decreases the SDMC amount and, as the result, suppresses the gamma-ray signal from DM annihilation.

  20. What to expect from dynamical modelling of galactic haloes - II. The spherical Jeans equation

    Science.gov (United States)

    Wang, Wenting; Han, Jiaxin; Cole, Shaun; More, Surhud; Frenk, Carlos; Schaller, Matthieu

    2018-06-01

    The spherical Jeans equation (SJE) is widely used in dynamical modelling of the Milky Way (MW) halo potential. We use haloes and galaxies from the cosmological Millennium-II simulation and hydrodynamical APOSTLE (A Project of Simulations of The Local Environment) simulations to investigate the performance of the SJE in recovering the underlying mass profiles of MW mass haloes. The best-fitting halo mass and concentration parameters scatter by 25 per cent and 40 per cent around their input values, respectively, when dark matter particles are used as tracers. This scatter becomes as large as a factor of 3 when using star particles instead. This is significantly larger than the estimated statistical uncertainty associated with the use of the SJE. The existence of correlated phase-space structures that violate the steady-state assumption of the SJE as well as non-spherical geometries is the principal source of the scatter. Binary haloes show larger scatter because they are more aspherical in shape and have a more perturbed dynamical state. Our results confirm that the number of independent phase-space structures sets an intrinsic limiting precision on dynamical inferences based on the steady-state assumption. Modelling with a radius-independent velocity anisotropy, or using tracers within a limited outer radius, result in significantly larger scatter, but the ensemble-averaged measurement over the whole halo sample is approximately unbiased.

  1. Could there be a hole in type Ia supernovae?

    International Nuclear Information System (INIS)

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-01-01

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity

  2. Design of pre-optics for laser guide star wavefront sensor for the ELT

    Science.gov (United States)

    Muslimov, Eduard; Dohlen, Kjetil; Neichel, Benoit; Hugot, Emmanuel

    2017-12-01

    In the present paper, we consider the optical design of a zoom system for the active refocusing in laser guide star wavefront sensors. The system is designed according to the specifications coming from the Extremely Large Telescope (ELT)-HARMONI instrument, the first-light, integral field spectrograph for the European (E)-ELT. The system must provide a refocusing of the laser guide as a function of telescope pointing and large decentring of the incoming beam. The system considers four moving lens groups, each of them being a doublet with one aspherical surface. The advantages and shortcomings of such a solution in terms of the component displacements and complexity of the surfaces are described in detail. It is shown that the system can provide the median value of the residual wavefront error of 13.8-94.3 nm and the maximum value <206 nm, while the exit pupil distortion is 0.26-0.36% for each of the telescope pointing directions.

  3. Optical design of the PEPSI high-resolution spectrograph at LBT

    Science.gov (United States)

    Andersen, Michael I.; Spano, Paolo; Woche, Manfred; Strassmeier, Klaus G.; Beckert, Erik

    2004-09-01

    PEPSI is a high-resolution, fiber fed echelle spectrograph with polarimetric capabilities for the LBT. In order to reach a maximum resolution R=120.000 in polarimetric mode and 300.000 in integral light mode with high efficiency in the spectral range 390-1050~nm, we designed a white-pupil configuration with Maksutov collimators. Light is dispersed by an R4 31.6 lines/mm monolithic echelle grating mosaic and split into two arms through dichroics. The two arms, optimized for the spectral range 390-550~nm and 550-1050~nm, respectively, consist of Maksutov transfer collimators, VPH-grism cross dispersers, optimized dioptric cameras and 7.5K x 7.5K 8~μ CCDs. Fibers of different core sizes coupled to different image-slicers allow a high throughput, comparable to that of direct feed instruments. The optical configuration with only spherical and cylindrical surfaces, except for one aspherical surface in each camera, reduces costs and guarantees high optical quality. PEPSI is under construction at AIP with first light expected in 2006.

  4. Time-resolved Polarimetry of the Superluminous SN 2015bn with the Nordic Optical Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Leloudas, Giorgos; Gal-Yam, Avishay [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Maund, Justyn R. [The Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Pursimo, Tapio [Nordic Optical Telescope, Apartado 474, E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife (Spain); Hsiao, Eric [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Malesani, Daniele; De Ugarte Postigo, Antonio [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-2100 Copenhagen (Denmark); Patat, Ferdinando [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Sollerman, Jesper [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Stritzinger, Maximilian D. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Wheeler, J. Craig [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)

    2017-03-01

    We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between −20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs of spectropolarimetry are also available. Based on field stars, we determine the interstellar polarization in the Galaxy to be negligible. The polarization of SN 2015bn shows a statistically significant increase during the last epochs, confirming previous findings. Our well-sampled imaging polarimetry series allows us to determine that this increase (from ∼0.54% to ≳1.10%) coincides in time with rapid changes that took place in the optical spectrum. We conclude that the supernova underwent a “phase transition” at around +20 days, when the photospheric emission shifted from an outer layer, dominated by natal C and O, to a more aspherical inner core, dominated by freshly nucleosynthesized material. This two-layered model might account for the characteristic appearance and properties of Type I superluminous supernovae.

  5. GALEX: a UV telescope to map the star formation history of the universe

    Science.gov (United States)

    Milliard, Bruno; Grange, Robert; Martin, Christopher; Schiminovich, David

    2017-11-01

    The NASA Small Mission EXplorer GALEX (PI: C.Martin, Caltech) is under development at JPL for launch late 2001. It has been designed to map the history of star formation in the Universe over the redshift range 0-2, a major era where galaxies and gas content evolved dramatically. The expected depth and imaging quality matches the Palomar Observatory Surveys, allowing GALEX to provide the astronomical community with a database of FUV photometric and spectroscopic observations of several million galaxies in the nearby and distant Universe. The 1.24 degree FOV, 50 cm aperture compact Ritchey-Chrétien telescope is equipped with two 65 mm photon-counting detectors. It will perform several surveys of different coverage and depths, that will take advantage of a high throughput UV-transmissive Grism newly developed in France to easily switch between imagery and field spectroscopy modes. A thin aspherized fused silica dichroic component provides simultaneous observations in two UV bands (135-185 nm and 185-300 nm) as well as correction for field aberrations. We shall briefly present the mission science goals, and will describe the optical concept, along with the guidelines and compromises used for its optimization in the context of the "Faster, Better, Cheaper" NASA philosophy, and give a brief development status report.

  6. The optical design of ultra-short throw system for panel emitted theater video system

    Science.gov (United States)

    Huang, Jiun-Woei

    2015-07-01

    In the past decade, the display format from (HD High Definition) through Full HD(1920X1080) to UHD(4kX2k), mainly guides display industry to two directions: one is liquid crystal display(LCD) from 10 inch to 100 inch and more, and the other is projector. Although LCD has been popularly used in market; however, the investment for production such kind displays cost more money expenditure, and less consideration of environmental pollution and protection[1]. The Projection system may be considered, due to more viewing access, flexible in location, energy saving and environmental protection issues. The topic is to design and fabricate a short throw factor liquid crystal on silicon (LCoS) projection system for cinema. It provides a projection lens system, including a tele-centric lens fitted for emitted LCoS to collimate light to enlarge the field angle. Then, the optical path is guided by a symmetric lens. Light of LCoS may pass through the lens, hit on and reflect through an aspherical mirror, to form a less distortion image on blank wall or screen for home cinema. The throw ratio is less than 0.33.

  7. Laser Beam delivering and shaping device for transfer of organic film

    International Nuclear Information System (INIS)

    Lee, Kangin; Kwon, Jin Hyuk; Yi, Jonghoon

    2008-01-01

    The laser based organic material transfer methods are developed by several groups for OLED (organic light emitting diode)fabrication. Well developed laser based methods are LITI (Laser Induced Thermal Imaging)and LIPS (Laser Induced Pattern wise Sublimation). These methods are proved to be suitable for large OLED panel fabrication. At an early stage of development, TEM"00"mode Nd:YAG laser was used for pattering organic material. The focused focused Nd:YAG laser beam generated heat in the film and the heat caused expansion of organic material coated layer. The organic film on the layer is transferred to the display panel due to pressure exerted on the display panel by the layer. Recently developed system prefers to employ a diode laser with wavelength of 800nm. Diode laser is cheaper and smaller photon source compared with the Nd:YAG laser. In this work, we use Nd doped fiber laser (wavelength=1070nm, power=10W)because the laser has stable output and well defined Gaussian beam profile compared with diode laser. We also employed fiber coupled diode laser (808nm)because it also has well defined beam distribution. In laser methods, spatially shaped beam is required for clean and sharp transfer. There are several methods for the beam shaping such as aspheric lens, diffractive optical elements, and micro lens array etc. We found that Gaussian beam can be shaped to a square hat like beam just by using simple commercial spherical lens set

  8. Nucleus-size pinning for determination of nucleation free-energy barriers and nucleus geometry

    Science.gov (United States)

    Sharma, Abhishek K.; Escobedo, Fernando A.

    2018-05-01

    Classical Nucleation Theory (CNT) has recently been used in conjunction with a seeding approach to simulate nucleation phenomena at small-to-moderate supersaturation conditions when large free-energy barriers ensue. In this study, the conventional seeding approach [J. R. Espinosa et al., J. Chem. Phys. 144, 034501 (2016)] is improved by a novel, more robust method to estimate nucleation barriers. Inspired by the interfacial pinning approach [U. R. Pedersen, J. Chem. Phys. 139, 104102 (2013)] used before to determine conditions where two phases coexist, the seed of the incipient phase is pinned to a preselected size to iteratively drive the system toward the conditions where the seed becomes a critical nucleus. The proposed technique is first validated by estimating the critical nucleation conditions for the disorder-to-order transition in hard spheres and then applied to simulate and characterize the highly non-trivial (prolate) morphology of the critical crystal nucleus in hard gyrobifastigia. A generalization of CNT is used to account for nucleus asphericity and predict nucleation free-energy barriers for gyrobifastigia. These predictions of nuclei shape and barriers are validated by independent umbrella sampling calculations.

  9. Wide-field schematic eye models with gradient-index lens.

    Science.gov (United States)

    Goncharov, Alexander V; Dainty, Chris

    2007-08-01

    We propose a wide-field schematic eye model, which provides a more realistic description of the optical system of the eye in relation to its anatomical structure. The wide-field model incorporates a gradient-index (GRIN) lens, which enables it to fulfill properties of two well-known schematic eye models, namely, Navarro's model for off-axis aberrations and Thibos's chromatic on-axis model (the Indiana eye). These two models are based on extensive experimental data, which makes the derived wide-field eye model also consistent with that data. A mathematical method to construct a GRIN lens with its iso-indicial contours following the optical surfaces of given asphericity is presented. The efficiency of the method is demonstrated with three variants related to different age groups. The role of the GRIN structure in relation to the lens paradox is analyzed. The wide-field model with a GRIN lens can be used as a starting design for the eye inverse problem, i.e., reconstructing the optical structure of the eye from off-axis wavefront measurements. Anatomically more accurate age-dependent optical models of the eye could ultimately help an optical designer to improve wide-field retinal imaging.

  10. Accuracy of Topcon CM-1000 videokeratoscope on spherical test surfaces.

    Science.gov (United States)

    Pérez-Yern, E; Fimia-Gil, A; Mateos, F; Carretero, L

    1997-01-01

    Many videokeratoscopes use mathematical formulas to calculate corneal radii; calculations depend on slope, curvature, coordinate position, or focal properties of the surface. Accuracy of each type of videokeratoscope must be evaluated. A controversy exists about whether axial or tangential methods best provide a precise description of corneal shape; therefore results with the Topcon CM-1000 using both methods were evaluated. Measurements were done on black polymethylmethacrylate (PMMA) spherical calibrated surfaces. Lenses were first aligned and measured and then misaligned in different directions and measured. Results for each position were compared with the zero or alignment position. Accuracy of the CM-1000 was high even under extreme misalignment conditions. Tolerance to misalignment was high (about 300 mm). Misalignment-induced variations in the output results were small (usually less than 0.05 mm). However, important variations (more than 1.00 diopter [D]) were found for the lowest measured radius (6 mm). In some cases, small differences between axial and tangential radii for the same point could be found. With the exception of extremely low radii of curvature, the CM-1000 was accurate for measuring spherical surfaces. Further investigation remains to be done on aspheric surfaces and in clinical practice.

  11. Interferometry with flexible point source array for measuring complex freeform surface and its design algorithm

    Science.gov (United States)

    Li, Jia; Shen, Hua; Zhu, Rihong; Gao, Jinming; Sun, Yue; Wang, Jinsong; Li, Bo

    2018-06-01

    The precision of the measurements of aspheric and freeform surfaces remains the primary factor restrict their manufacture and application. One effective means of measuring such surfaces involves using reference or probe beams with angle modulation, such as tilted-wave-interferometer (TWI). It is necessary to improve the measurement efficiency by obtaining the optimum point source array for different pieces before TWI measurements. For purpose of forming a point source array based on the gradients of different surfaces under test, we established a mathematical model describing the relationship between the point source array and the test surface. However, the optimal point sources are irregularly distributed. In order to achieve a flexible point source array according to the gradient of test surface, a novel interference setup using fiber array is proposed in which every point source can be independently controlled on and off. Simulations and the actual measurement examples of two different surfaces are given in this paper to verify the mathematical model. Finally, we performed an experiment of testing an off-axis ellipsoidal surface that proved the validity of the proposed interference system.

  12. Varied line-space gratings: past, present and future

    International Nuclear Information System (INIS)

    Hettrick, M.C.

    1985-08-01

    A classically ruled diffraction grating consists of grooves which are equidistant, straight and parallel. Conversely, the so-called ''holographic'' grating (formed by the interfering waves of coherent visible light), although severely constrained by the recording wavelength and recording geometry, has grooves which are typically neither equidistant, straight nor parallel. In contrast, a varied line-space (VLS) grating, in common nomenclature, is a design in which the groove positions are relatively unconstrained yet possess sufficient symmetry to permit mechanical ruling. Such seemingly exotic gratings are no longer only a theoretical curiosity, but have been ruled and used in a wide variety of applications. These include: (1) aberration-corrected normal incidence concave gratings for Seya-Namioka monochromators and optical de-multiplexers, (2) flat-field grazing incidence concave gratings for plasma diagnostics, (3) aberration-corrected grazing incidence plane gratings for space-borne spectrometers, (4) focusing grazing incidence plane grating for synchrotron radiation monochromators, and (5) wavefront generators for visible interferometry of optical surfaces (particularly aspheres). Future prospects of VLS gratings as dispersing elements, wavefront correctors and beamsplitters appear promising. The author discusses the history of VLS gratings, their present applications, and their potential in the future. 61 refs., 24 figs

  13. Optical design of an athermalised dual field of view step zoom optical system in MWIR

    Science.gov (United States)

    Kucukcelebi, Doruk

    2017-08-01

    In this paper, the optical design of an athermalised dual field of view step zoom optical system in MWIR (3.7μm - 4.8μm) is described. The dual field of view infrared optical system is designed based on the principle of passive athermalization method not only to achieve athermal optical system but also to keep the high image quality within the working temperature between -40°C and +60°C. The infrared optical system used in this study had a 320 pixel x 256 pixel resolution, 20μm pixel pitch size cooled MWIR focal plane array detector. In this study, the step zoom mechanism, which has the axial motion due to consisting of a lens group, is considered to simplify mechanical structure. The optical design was based on moving a single lens along the optical axis for changing the optical system's field of view not only to reduce the number of moving parts but also to athermalize for the optical system. The optical design began with an optimization process using paraxial optics when first-order optics parameters are determined. During the optimization process, in order to reduce aberrations, such as coma, astigmatism, spherical and chromatic aberrations, aspherical surfaces were used. As a result, athermalised dual field of view step zoom optical design is proposed and the performance of the design using proposed method was verified by providing the focus shifts, spot diagrams and MTF analyzes' plots.

  14. NANOMETER PRECISION IN LARGE SURFACE PROFILOMETRY

    International Nuclear Information System (INIS)

    TAKACS, P.Z.

    1999-01-01

    The Long Trace Profiler (LTP) is in use at many synchrotron radiation (SR) laboratories throughout the world and by a number of manufacturers who specialize in fabricating grazing incidence mirrors for SR and x-ray telescope applications. Recent improvements in the design and operation of the LTP system have reduced the statistical error in slope profile measurement to the 1 standard deviation level of 0.3 microradian for 0.5 meter long mirrors. This corresponds to a height error on the order of 10-20 nanometers. This level of performance allows one to measure with confidence the absolute shape of large cylindrical aspheres and spheres that have kilometer radii of curvature in the axial direction. The LTP is versatile enough to make measurements of a mirror in the face up, sideways, and face down configurations. We will illustrate the versatility of the current version of the instrument, the LTP II, and present results from two new versions of the instrument: the in situ LTP (ISLTP) and the Vertical Scan LTP (VSLTP). Both of them are based on the penta prism LTP (ppLTP) principle that utilizes a stationary optical head and moving penta prism. The ISLTP is designed to measure the distortion of high heat load mirrors during actual operation in SR beam lines. The VSLTP is designed to measure the complete 3-dimensional shape of x-ray telescope cylinder mirrors and mandrels in a vertical configuration. Scans are done both in the axial direction and in the azimuthal direction

  15. LASIK for myopia and astigmatism using the SCHWIND AMARIS excimer laser: an international multicenter trial.

    Science.gov (United States)

    Arbelaez, Maria Clara; Aslanides, Ioannis M; Barraquer, Carmen; Carones, Francesco; Feuermannova, Alena; Neuhann, Tobias; Rozsival, Pavel

    2010-02-01

    To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate myopia with astigmatism using the SCHWIND AMARIS excimer laser. Six international study sites enrolled 358 eyes with a manifest refraction spherical equivalent (MRSE) from -0.50 to -7.38 diopters (D) (mean sphere: -3.13+/-1.58 D) with up to -5.00 D of astigmatism (mean: -0.69+/-0.67 D). All eyes underwent treatment with the nonwavefront-guided aspheric algorithm of the SCHWIND AMARIS excimer laser. All eyes were targeted for emmetropia. Refractive outcomes and corneal higher order aberrations were analyzed pre- and postoperatively. Visual quality was assessed using photopic and mesopic contrast sensitivity. Six-month postoperative outcomes are reported. At 6 months postoperative, the MRSE for all eyes was -0.21+/-0.20 D, and 96% (343/358) of eyes had MRSE within +/-0.50 D. Uncorrected visual acuity was 20/20 or better in 98% (351/358) of eyes, and no eyes lost 2 or more lines of best spectacle-corrected visual acuity. The total corneal higher order aberrations root-mean-square increased by 0.09 microm, spherical aberration increased by 0.08 microm, and coma increased by 0.04 microm postoperatively. Photopic and mesopic contrast sensitivity did not change 6 months postoperatively. Treatment of myopia with astigmatism using the SCHWIND AMARIS excimer laser is safe, efficacious, predictable, and maintains visual quality.

  16. Late Disciform Endotheliitis after LASIK

    Directory of Open Access Journals (Sweden)

    Faik Oruçoğlu

    2013-08-01

    Full Text Available Clinical and imaging features of the patient with late herpetic keratouveitis after LASIK were investigated. A 25-year-old male patient applied with a chief complaint of blurred vision and photophobia in the left eye. He had a history of herpetic keratitits and elsewhere underwent LASIK procedure in 2005. Oral and topical acyclovir treatments were started a week ago when his complaints started. His corrected distance visual acuity was 0.2 and intraocular pressure was 14 mmHg on the left eye. Slit-lamp revealed deep central disciform edema, keratic precipitates, and 2 positive cells in the anterior chamber. Although the patient had myopic LASIK ablation, the central corneal thickness was 652 microns. Scheimpflug imaging was drawing attention to the thickening of the posterior cornea and the keratic precipitates. Sagital and anterior elevation maps were not affected, however, posterior elevation map showed marked central flattening. Asphericity value Q was within normal limits anteriorly (Q=-0.14 and it was in oblate appearance posteriorly (Q=+5.24. In addition to the antiviral medications, a topical dexamethasone treatment was started. The vision improved to 0.6, and the edema was markedly reduced after 4 days of treatment. Scheimpflug imaging parameters were significantly improved. (Turk J Ophthalmol 2013; 43: 282-5

  17. Quantifying the abnormal hemodynamics of sickle cell anemia

    Science.gov (United States)

    Lei, Huan; Karniadakis, George

    2012-02-01

    Sickle red blood cells (SS-RBC) exhibit heterogeneous morphologies and abnormal hemodynamics in deoxygenated states. A multi-scale model for SS-RBC is developed based on the Dissipative Particle Dynamics (DPD) method. Different cell morphologies (sickle, granular, elongated shapes) typically observed in deoxygenated states are constructed and quantified by the Asphericity and Elliptical shape factors. The hemodynamics of SS-RBC suspensions is studied in both shear and pipe flow systems. The flow resistance obtained from both systems exhibits a larger value than the healthy blood flow due to the abnormal cell properties. Moreover, SS-RBCs exhibit abnormal adhesive interactions with both the vessel endothelium cells and the leukocytes. The effect of the abnormal adhesive interactions on the hemodynamics of sickle blood is investigated using the current model. It is found that both the SS-RBC - endothelium and the SS-RBC - leukocytes interactions, can potentially trigger the vicious ``sickling and entrapment'' cycles, resulting in vaso-occlusion phenomena widely observed in micro-circulation experiments.

  18. Corneal topographer based on the Hartmann test.

    Science.gov (United States)

    Mejía, Yobani; Galeano, Janneth C

    2009-04-01

    The purpose of this article is to show the performance of a topographer based on the Hartmann test for convex surfaces of F/# approximately 1. This topographer, called "Hartmann Test topographer (HT topographer)," is a prototype developed in the Physics Department of the Universidad Nacional de Colombia. From the Hartmann pattern generated by the surface under test, and by the Fourier analysis and the optical aberration theory we obtain the sagitta (elevation map) of the surface. Then, taking the first and the second derivatives of the sagitta in the radial direction we obtain the meridional curvature map. The method is illustrated with an example. To check the performance of the HT topographer a toric surface, a revolution aspherical surface, and two human corneas were measured. Our results are compared with those obtained with a Placido ring topographer (Tomey TMS-4 videokeratoscope), and we show that our curvature maps are similar to those obtained with the Placido ring topographer. The HT topographer is able to reconstruct the corneal topography potentially eradicating the skew ray problem, therefore, corneal defects can be visualized more. The results are presented by elevation and meridional curvature maps.

  19. THE SPATIAL DISTRIBUTION OF OH AND CN RADICALS IN THE COMA OF COMET ENCKE

    International Nuclear Information System (INIS)

    Ihalawela, Chandrasiri A.; Pierce, Donna M.; Dorman, Garrett R.; Cochran, Anita L.

    2011-01-01

    Multiple potential parent species have been proposed to explain CN abundances in comet comae, but the parent has not been definitively identified for all comets. This study examines the spatial distribution of CN radicals in the coma of comet Encke and determines the likelihood that CN is a photodissociative daughter of HCN in the coma. Comet Encke is the shortest orbital period (3.3 years) comet known and also has a low dust-to-gas ratio based on optical observations. Observations of CN were obtained from 2003 October 22 to 24, using the 2.7 m telescope at McDonald Observatory. To determine the parent of CN, the classical vectorial model was modified by using a cone shape in order to reproduce Encke's highly aspherical and asymmetric coma. To test the robustness of the modified model, the spatial distribution of OH was also modeled. This also allowed us to obtain CN/OH ratios in the coma. Overall, we find the CN/OH ratio to be 0.009 ± 0.004. The results are consistent with HCN being the photodissociative parent of CN, but we cannot completely rule out other possible parents such as CH 3 CN and HC 3 N. We also found that the fan-like feature spans ∼90°, consistent with the results of Woodney et al..

  20. Refractive results of cataract surgery using optical biometry and Haigis formula in eyes with refractive keratotomy

    Directory of Open Access Journals (Sweden)

    Juan Carlos Sánchez Caballero

    2013-04-01

    Full Text Available OBJECTIVE: To analyze refractive results in postoperative cataract surgery in eyes previously submitted to keratotomy using Haigis formula and data provided by IOL Master®optical biometer. METHODS: The measurements for IOL calculation were obtained through optical biometry by partial coherence interferometry (IOL Master®- Zeiss, 5.4 and 5.5 version that provides us with the axial length, the central keratometry of 2.5mm, white-to-white diameter and anterior chamber anatomical depth. The formula chosen was Haigis. The surgical technique applied was with the scleral incision at 1.5 mm from the limbus, with scleral-corneal tunnel of 2.2 mm wide, phacoemulsification using INFINITI Ozil®- Alcon and implantation of hydrophobic acrylic aspheric intraocular lens - SN60WF®- Alcon. RESULTS: We studied 20 eyes submitted to keratotomy in the past and currently with cataract with indication for cataract surgerywith intraocular lens implantation using phacoemulsification. Postoperative spherical equivalent was plano in 40% of the eyes and lower than -1.00 in 85% of the eyes. CONCLUSION: The optical biometry by partial coherence interferometry associated with Haigis formula is a valid alternative in IOL calculation for eyes submitted to keratotomy. The refractive results are highly predictable and reproducible.

  1. Smaller incision size leads to higher predictability in microcoaxial cataract surgery.

    Science.gov (United States)

    Klamann, Matthias K J; Gonnermann, Johannes; Maier, Anna-Karina B; Torun, Necip; Bertelmann, Eckart

    2013-01-01

    The aim of the study was to compare the clinical outcomes of a 1.8 mm, 2.2 mm, and 2.75 mm microcoaxial cataract surgery system. METHODS. In this retrospective study, 129 eyes of 129 patients were included. Patients underwent phacoemulsification using a Stellaris system or an Infiniti system. The incision size was 1.8 mm, 2.2 mm, or 2.75 mm, respectively. Subjects were examined before surgery and 4 weeks after. The surgically induced astigmatism (SIA) was examined. The SIA in the 1.8 mm group was statistically lower compared to the 2.2 mm group (p=0.046) and the 2.75 mm group (p=0.017). There was no significant difference between the 2.2 mm group and the 2.75 mm group. With the use of appropriate support systems, 1.8 mm incisions appear to result in less SIA than 2.2 mm and 2.75 mm incisions. Advantages may arise from this, especially in the implantation of aspheric, toric, or multifocal lenses.

  2. Luminescence from cavitation bubbles deformed in uniform pressure gradients

    Science.gov (United States)

    Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Farhat, Mohamed

    2017-09-01

    Presented here are observations that demonstrate how the deformation of millimetric cavitation bubbles by a uniform pressure gradient quenches single-collapse luminescence. Our innovative measurement system captures a broad luminescence spectrum (wavelength range, 300-900 nm) from the individual collapses of laser-induced bubbles in water. By varying the bubble size, driving pressure, and perceived gravity level aboard parabolic flights, we probed the limit from aspherical to highly spherical bubble collapses. Luminescence was detected for bubbles of maximum radii within the previously uncovered range, R0=1.5 -6 mm, for laser-induced bubbles. The relative luminescence energy was found to rapidly decrease as a function of the bubble asymmetry quantified by the anisotropy parameter ζ , which is the dimensionless equivalent of the Kelvin impulse. As established previously, ζ also dictates the characteristic parameters of bubble-driven microjets. The threshold of ζ beyond which no luminescence is observed in our experiment closely coincides with the threshold where the microjets visibly pierce the bubble and drive a vapor jet during the rebound. The individual fitted blackbody temperatures range between Tlum=7000 and Tlum=11 500 K but do not show any clear trend as a function of ζ . Time-resolved measurements using a high-speed photodetector disclose multiple luminescence events at each bubble collapse. The averaged full width at half-maximum of the pulse is found to scale with R0 and to range between 10 and 20 ns.

  3. A new code for the design and analysis of the heliostat field layout for power tower system

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiudong; Lu, Zhenwu; Yu, Weixing [Changchun Institute of Optics, Fine Mechanics and Physics of Chinese Academy of Sciences, Changchun 130033 (China); Wang, Zhifeng [The Key Laboratory of Solar Thermal Energy and Photovoltaic system, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-04-15

    A new code for the design and analysis of the heliostat field layout for power tower system is developed. In the new code, a new method for the heliostat field layout is proposed based on the edge ray principle of nonimaging optics. The heliostat field boundary is constrained by the tower height, the receiver tilt angle and size and the heliostat efficiency factor which is the product of the annual cosine efficiency and the annual atmospheric transmission efficiency. With the new method, the heliostat can be placed with a higher efficiency and a faster response speed of the design and optimization can be obtained. A new module for the analysis of the aspherical heliostat is created in the new code. A new toroidal heliostat field is designed and analyzed by using the new code. Compared with the spherical heliostat, the solar image radius of the field is reduced by about 30% by using the toroidal heliostat if the mirror shape and the tracking are ideal. In addition, to maximize the utilization of land, suitable crops can be considered to be planted under heliostats. To evaluate the feasibility of the crop growth, a method for calculating the annual distribution of sunshine duration on the land surface is developed as well. (author)

  4. K2 photometry and HERMES spectroscopy of the blue supergiant ρ Leo: rotational wind modulation and low-frequency waves

    Science.gov (United States)

    Aerts, C.; Bowman, D. M.; Símon-Díaz, S.; Buysschaert, B.; Johnston, C.; Moravveji, E.; Beck, P. G.; De Cat, P.; Triana, S.; Aigrain, S.; Castro, N.; Huber, D.; White, T.

    2018-05-01

    We present an 80-d long uninterrupted high-cadence K2 light curve of the B1Iab supergiant ρ Leo (HD 91316), deduced with the method of halo photometry. This light curve reveals a dominant frequency of frot = 0.0373 d-1 and its harmonics. This dominant frequency corresponds with a rotation period of 26.8 d and is subject to amplitude and phase modulation. The K2 photometry additionally reveals multiperiodic low-frequency variability (<1.5 d-1) and is in full agreement with low-cadence high-resolution spectroscopy assembled during 1800 d. The spectroscopy reveals rotational modulation by a dynamic aspherical wind with an amplitude of about 20 km s-1 in the H α line, as well as photospheric velocity variations of a few km s-1 at frequencies in the range 0.2-0.6 d-1 in the Si III 4567 Å line. Given the large macroturbulence needed to explain the spectral line broadening of the star, we interpret the detected photospheric velocity as due to travelling superinertial low-degree large-scale gravity waves with dominant tangential amplitudes and discuss why ρ Leo is an excellent target to study how the observed photospheric variability propagates into the wind.

  5. News from EUPHA

    Directory of Open Access Journals (Sweden)

    EUPHA 17th European Conference on Public Health

    2009-06-01

    Full Text Available It is very good news for Italian participation at this year’s EUPHA meeting, which will be held in Lodz (Poland. From 25 to 28 November the joint annual conference EUPHA-ASPHER will see a peaceful “invasion” from Italy. Out of the 63 Italian abstracts submitted to the conference organisers, only 5 (7.9% were rejected. Overall, 11.6% of all of the accepted abstracts are Italian, 9.8% of the oral presentations and 13% of the poster presentations. These results pay testimony to the high quality of European public health research and practice reached in several fields and settings (academic, public health regional agencies, and local health units. Highlights from Italy include the ongoing work in the field of infectious disease control, Stefania Bruno (Catholic University will present the Roman experience of Tubercolosis surveillance in the homeless. Maria De Giusti (Sapienza University presents “Knowledge, attitudes and behaviour towards Methicillin-resistant Staphylococcus aureus skin infections and S. aureus nasal colonisation”; while Chiara de Waure (Catholic University will present “Rapid screening tests for MRSA carriage at hospital admission: a systematic review”.

  6. Medium-sized aperture camera for Earth observation

    Science.gov (United States)

    Kim, Eugene D.; Choi, Young-Wan; Kang, Myung-Seok; Kim, Ee-Eul; Yang, Ho-Soon; Rasheed, Ad. Aziz Ad.; Arshad, Ahmad Sabirin

    2017-11-01

    Satrec Initiative and ATSB have been developing a medium-sized aperture camera (MAC) for an earth observation payload on a small satellite. Developed as a push-broom type high-resolution camera, the camera has one panchromatic and four multispectral channels. The panchromatic channel has 2.5m, and multispectral channels have 5m of ground sampling distances at a nominal altitude of 685km. The 300mm-aperture Cassegrain telescope contains two aspheric mirrors and two spherical correction lenses. With a philosophy of building a simple and cost-effective camera, the mirrors incorporate no light-weighting, and the linear CCDs are mounted on a single PCB with no beam splitters. MAC is the main payload of RazakSAT to be launched in 2005. RazakSAT is a 180kg satellite including MAC, designed to provide high-resolution imagery of 20km swath width on a near equatorial orbit (NEqO). The mission objective is to demonstrate the capability of a high-resolution remote sensing satellite system on a near equatorial orbit. This paper describes the overview of the MAC and RarakSAT programmes, and presents the current development status of MAC focusing on key optical aspects of Qualification Model.

  7. Omega-X micromachining system

    International Nuclear Information System (INIS)

    Miller, D.M.

    1978-01-01

    A micromachining tool system with X- and omega-axes is used to machine spherical, aspherical, and irregular surfaces with a maximum contour error of 100 nonometers (nm) and surface waviness of no more than 0.8 nm RMS. The omega axis, named for the angular measurement of the rotation of an eccentric mechanism supporting one end of a tool bar, enables the pulse increments of the tool toward the workpiece to be as little as 0 to 4.4 nm. A dedicated computer coordinates motion in the two axes to produce the workpiece contour. Inertia is reduced by reducing the mass pulsed toward the workpiece to about one-fifth of its former value. The tool system includes calibration instruments to calibrate the micromachining tool system. Backlash is reduced and flexing decreased by using a rotary table and servomotor to pulse the tool in the omega-axis instead of a ball screw mechanism. A thermally-stabilized spindle roates the workpiece and is driven by a motor not mounted on the micromachining tool base through a torque-smoothing pulley and vibrationless rotary coupling. Abbe offset errors are almost eliminated by tool setting and calibration at spindle center height. Tool contour and workpiece contour are gaged on the machine; this enables the source of machining errors to be determined more readily, because the workpiece is gaged before its shape can be changed by removal from the machine

  8. Brightness checkerboard lattice method for the calibration of the coaxial reverse Hartmann test

    Science.gov (United States)

    Li, Xinji; Hui, Mei; Li, Ning; Hu, Shinan; Liu, Ming; Kong, Lingqin; Dong, Liquan; Zhao, Yuejin

    2018-01-01

    The coaxial reverse Hartmann test (RHT) is widely used in the measurement of large aspheric surfaces as an auxiliary method for interference measurement, because of its large dynamic range, highly flexible test with low frequency of surface errors, and low cost. And the accuracy of the coaxial RHT depends on the calibration. However, the calibration process remains inefficient, and the signal-to-noise ratio limits the accuracy of the calibration. In this paper, brightness checkerboard lattices were used to replace the traditional dot matrix. The brightness checkerboard method can reduce the number of dot matrix projections in the calibration process, thus improving efficiency. An LCD screen displayed a brightness checkerboard lattice, in which the brighter checkerboard and the darker checkerboard alternately arranged. Based on the image on the detector, the relationship between the rays at certain angles and the photosensitive positions of the detector coordinates can be obtained. And a differential de-noising method can effectively reduce the impact of noise on the measurement results. Simulation and experimentation proved the feasibility of the method. Theoretical analysis and experimental results show that the efficiency of the brightness checkerboard lattices is about four times that of the traditional dot matrix, and the signal-to-noise ratio of the calibration is significantly improved.

  9. Conjugacy in relatively extra-large Artin groups

    Directory of Open Access Journals (Sweden)

    Arye Juhasz

    2015-09-01

    Full Text Available Let A be an Artin group with standard generators X={x 1 ,…,x n } , n≥1 and defining graph Γ A . A \\emph{standard parabolic subgroup} of A is a subgroup generated by a subset of X . For elements u and v of A we say (as usual that u is conjugate to v by an element h of A if h −1 uh=v holds in A . Similarly, if K and L are subsets of A then K is conjugate to L by an element h of A if h −1 Kh=L . In this work we consider the conjugacy of elements and standard parabolic subgroups of a certain type of Artin groups. Results in this direction occur in occur in papers by Duncan, Kazachkov, Remeslennikov, Fenn, Dale, Jun, Godelle, Gonzalez-Meneses, Wiest, Paris, Rolfsen, for example. Of particular interest are centralisers of elements, and of standard parabolic subgroups, normalisers of standard parabolic subgroups and commensurators of parabolic subgroups. In this work we consider similar problems in a new class of Artin groups, introduced in the paper "On relatively extralarge Artin groups and their relative asphericity", by Juhasz, where the word problem is solved, among other things. Also, intersections of parabolic subgroups and their conjugates are considered.

  10. Silicon carbide optics for space and ground based astronomical telescopes

    Science.gov (United States)

    Robichaud, Joseph; Sampath, Deepak; Wainer, Chris; Schwartz, Jay; Peton, Craig; Mix, Steve; Heller, Court

    2012-09-01

    Silicon Carbide (SiC) optical materials are being applied widely for both space based and ground based optical telescopes. The material provides a superior weight to stiffness ratio, which is an important metric for the design and fabrication of lightweight space telescopes. The material also has superior thermal properties with a low coefficient of thermal expansion, and a high thermal conductivity. The thermal properties advantages are important for both space based and ground based systems, which typically need to operate under stressing thermal conditions. The paper will review L-3 Integrated Optical Systems - SSG’s (L-3 SSG) work in developing SiC optics and SiC optical systems for astronomical observing systems. L-3 SSG has been fielding SiC optical components and systems for over 25 years. Space systems described will emphasize the recently launched Long Range Reconnaissance Imager (LORRI) developed for JHU-APL and NASA-GSFC. Review of ground based applications of SiC will include supporting L-3 IOS-Brashear’s current contract to provide the 0.65 meter diameter, aspheric SiC secondary mirror for the Advanced Technology Solar Telescope (ATST).

  11. Synchrotron Radiation Lithography for Manufacturing Integrated Circuits Beyond 100 nm.

    Science.gov (United States)

    Kinoshita, H; Watanabe, T; Niibe, M

    1998-05-01

    Extreme ultraviolet lithography is a powerful tool for printing features of 0.1 micro m and below; in Japan and the USA there is a growing tendency to view it as the wave of the future. With Schwarzschild optics, replication of a 0.05 micro m pattern has been demonstrated in a 25 micro m square area. With a two-aspherical-mirror system, a 0.15 micro m pattern has been replicated in a ring slit area of 20 mm x 0.4 mm; a combination of this system with illumination optics and synchronized mask and wafer stages has enabled the replication of a 0.15 micro m pattern in an area of 10 mm x 12.5 mm. Furthermore, in the USA, the Sandia National Laboratory has succeeded in fabricating a fully operational NMOS transistor with a gate length of 0.1 micro m. The most challenging problem is the fabrication of mirrors with the required figure error of 0.28 nm. However, owing to advances in measurement technology, mirrors can now be made to a precision that almost satisfies this requirement. Therefore, it is time to move into a rapid development phase in order to obtain a system ready for practical use by the year 2004. In this paper the status of individual technologies is discussed in light of this situation, and future requirements for developing a practical system are considered.

  12. Metrology of reflection optics for synchrotron radiation

    International Nuclear Information System (INIS)

    Takacs, P.Z.

    1985-09-01

    Recent years have seen an almost explosive growth in the number of beam lines on new and existing synchrotron radiation facilities throughout the world. The need for optical components to utilize the unique characteristics of synchrotron radiation has increased accordingly. Unfortunately, the technology to manufacture and measure the large, smooth, exotic optical surfaces required to focus and steer the synchrotron radiation beam has not progressed as rapidly as the operational demands on these components. Most companies do not wish to become involved with a project that requires producing a single, very expensive, aspheric optic with surface roughness and figure tolerances that are beyond their capabilities to measure. This paper will review some of the experiences of the National Synchrotron Light Source in procuring grazing incidence optical components over the past several years. We will review the specification process - how it is related to the function of the optic, and how it relates to the metrology available during the manufacturing process and after delivery to the user's laboratory. We will also discuss practical aspects of our experience with new technologies, such as single point diamond turning of metal mirrors and the use of SiC as a mirror material. Recent advances in metrology instrumentation have the potential to move the measurement of surface figure and finish from the research laboratory into the optical shop, which should stimulate growth and interest in the manufacturing of optics to meet the needs of the synchrotron radiation user community

  13. THEORETICAL CLUES TO THE ULTRAVIOLET DIVERSITY OF TYPE Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Peter J.; Wang, Lifan [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Baron, E. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019-2061 (United States); Milne, Peter [Steward Observatory, University of Arizona, Tucson, AZ 85719 (United States); Roming, Peter W. A., E-mail: pbrown@physics.tamu.edu [Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 (United States)

    2015-08-10

    The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, {sup 56}Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects.

  14. Theoretical Clues to the Ultraviolet Diversity of Type Ia Supernovae

    Science.gov (United States)

    Brown, Peter J.; Baron, E.; Milne, Peter; Roming, Peter W. A.; Wang, Lifan

    2015-08-01

    The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, 56Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects.

  15. THEORETICAL CLUES TO THE ULTRAVIOLET DIVERSITY OF TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Brown, Peter J.; Wang, Lifan; Baron, E.; Milne, Peter; Roming, Peter W. A.

    2015-01-01

    The effect of metallicity on the observed light of Type Ia supernovae (SNe Ia) could lead to systematic errors as the absolute magnitudes of local and distant SNe Ia are compared to measure luminosity distances and determine cosmological parameters. The UV light may be especially sensitive to metallicity, though different modeling methods disagree as to the magnitude, wavelength dependence, and even the sign of the effect. The outer density structure, 56 Ni, and to a lesser degree asphericity, also impact the UV. We compute synthetic photometry of various metallicity-dependent models and compare to UV/optical photometry from the Swift Ultra-Violet/Optical Telescope. We find that the scatter in the mid-UV to near-UV colors is larger than predicted by changes in metallicity alone and is not consistent with reddening. We demonstrate that a recently employed method to determine relative abundances using UV spectra can be done using UVOT photometry, but we warn that accurate results require an accurate model of the cause of the variations. The abundance of UV photometry now available should provide constraints on models that typically rely on UV spectroscopy for constraining metallicity, density, and other parameters. Nevertheless, UV spectroscopy for a variety of supernova explosions is still needed to guide the creation of accurate models. A better understanding of the influences affecting the UV is important for using SNe Ia as cosmological probes, as the UV light may test whether SNe Ia are significantly affected by evolutionary effects

  16. The TMS-1 corneal topography measurement applied to calibrated ellipsoidal convex surfaces.

    Science.gov (United States)

    Douthwaite, W A; Matilla, M T

    1996-03-01

    The purpose of this report is to assess the accuracy of the TMS-1 videokeratoscope (Computed Anatomy Inc.) by using convex ellipsoidal surfaces. The ellipsoids were calibrated using Form Talysurf analysis, which allowed for subsequent calculation of the vertex radius and p value. The videokeratoscope was used to examine the same ellipsoids. The data provided by the instrument software were used to plot a graph of r2 verses y2, where r is the measured radius at y, the distance from the corneal point being measured to the optical axis of the instrument. The intercept on the ordinate of this graph gives the vertex radius, and the slope give the p value. The results arising from the Talysurf and the TMS-1 techniques were compared. The TMS-1 videokeratoscope gave readings for the vertex radius that were generally higher than those of the Talysurf analysis. The vertex radius was up to 0.09 mm greater. The p value results were similar by the two methods for p values of approximately 0.8; however, the TMS-1 results were higher, and the discrepancy increased as the p value approached that of a paraboloid. Although the videokeratoscope may be useful in comparative studies of the cornea, there must be some doubt about the absolute values displayed as the surface becomes increasingly aspheric.

  17. Acoustic lenses

    International Nuclear Information System (INIS)

    Kittmer, C.A.

    1983-03-01

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  18. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice

    Directory of Open Access Journals (Sweden)

    Guangxin Wang

    2016-01-01

    Full Text Available The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B0 inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained.

  19. Absolute surface reconstruction by slope metrology and photogrammetry

    Science.gov (United States)

    Dong, Yue

    Developing the manufacture of aspheric and freeform optical elements requires an advanced metrology method which is capable of inspecting these elements with arbitrary freeform surfaces. In this dissertation, a new surface measurement scheme is investigated for such a purpose, which is to measure the absolute surface shape of an object under test through its surface slope information obtained by photogrammetric measurement. A laser beam propagating toward the object reflects on its surface while the vectors of the incident and reflected beams are evaluated from the four spots they leave on the two parallel transparent windows in front of the object. The spots' spatial coordinates are determined by photogrammetry. With the knowledge of the incident and reflected beam vectors, the local slope information of the object surface is obtained through vector calculus and finally yields the absolute object surface profile by a reconstruction algorithm. An experimental setup is designed and the proposed measuring principle is experimentally demonstrated by measuring the absolute surface shape of a spherical mirror. The measurement uncertainty is analyzed, and efforts for improvement are made accordingly. In particular, structured windows are designed and fabricated to generate uniform scattering spots left by the transmitted laser beams. Calibration of the fringe reflection instrument, another typical surface slope measurement method, is also reported in the dissertation. Finally, a method for uncertainty analysis of a photogrammetry measurement system by optical simulation is investigated.

  20. Roger Hayward and the Invention of the Two-Mirror Schmidt

    Science.gov (United States)

    Bell, T. E.

    2005-12-01

    Roger Hayward (1899-1979), now virtually unknown, was a multitalented architect, scientific illustrator, and optical inventor. Remembered primarily for illustrating Scientific American magazine's Amateur Scientist column between 1949 and 1974, he also illustrated more than a dozen textbooks in optics, physics, geology, oceanography, and chemistry, several of which became classics in their fields. He designed façades with astronomical themes for major buildings in Los Angeles, California, and sculpted mammoth, realistic models of the moon for Griffith Observatory, Adler Planetarium, and Disneyland. Throughout his life, he recreationally painted watercolors and oils that at least one critic likened to the work of John Singer Sargent. Hayward is least known as an optical designer, yet he made significant contributions to the DU spectrophotometer that established the multimillion-dollar company Beckman Instruments. During the pre-radar days of World War II at Mount Wilson Observatory, Hayward invented a classified Cassegrain version of the Schmidt telescope especially adapted for nighttime infrared aerial photography, plus extraordinarily simple machines that allowed inexperienced soldiers to grind, polish, and test accurate aspheric Schmidt correcting plates at speeds compatible with mass production - and later received U.S. patents for them all. This paper, drawn in part from unpublished letters between Hayward and Albert G. Ingalls, will feature little-known images of Hayward's work.

  1. Equations of state of nonspherical fluids by spherical intermolecular potentials

    International Nuclear Information System (INIS)

    Bastea, S; Ree, F H

    1999-01-01

    The equilibrium properties of anisotropic molecular fluids can be in principle calculated in a statistical mechanics framework, but the theory is generally too cumbersome for many practical applications. Fortunately, at high densities and temperatures the anisotropy can be averaged-out by means of a density and temperature independent potential (the median) that produces reliable thermodynamics[1,2]. The proposal of Shaw and Johnson[1], which turns out to be the so-called median potential[2], is very successful in predicting the thermodynamics of simple fluids such as N(sub 2) and CO(sub 2) at reasonable high pressures and temperatures[3]. Lebowitz and Percus[2] pointed out some time ago that the success of this approximation could perhaps be understood in terms of a simple theory that treats the asphericity as a perturbation. The median appears to be the best choice for hard nonspherical potential[4], which may explain its success for fluids at high densities, where the hard core contribution is known to be dominant

  2. Dynamics of Small Inertia-Free Spheroidal Particles in a Turbulent Channel Flow

    Science.gov (United States)

    Challabotla, Niranjan Reddy; Zhao, Lihao; Andersson, Helge I.; Department of Energy; Process Engineering Team

    2015-11-01

    The study of small non-spherical particles suspended in turbulent fluid flows is of interest in view of the potential applications in industry and the environment. In the present work, we investigated the dynamics of inertia-free spheroidal particles suspended in fully-developed turbulent channel flow at Re τ = 180 by using the direct numerical simulations (DNS) for the Eulerian fluid phase coupled with the Lagrangian point-particle tracking. We considered inertia-free spheroidal particles with a wide range of aspect ratios from 0.01 to 50, i.e. from flat disks to long rods. Although the spheroids passively translate along with the fluid, the particle orientation and rotation strongly depend on the particle shape. The flattest disks were preferentially aligned with their symmetry axis normal to the wall, whereas the longest rods aligned parallel to the wall. Strong mean rotational spin was observed for spherical particles and this has been damped with increasing asphericity both for rod-like and disk-like spheroids. The anisotropic mean and fluctuating fluid vorticity resulted in particle spin anisotropies which exhibited a complex dependence on the particle asphericty. The Research Council of Norway, Notur and COST Action FP1005 are gratefully acknowledged.

  3. Poly(amidoamine) dendrimers on lipid bilayers II: Effects of bilayer phase and dendrimer termination.

    Science.gov (United States)

    Kelly, Christopher V; Leroueil, Pascale R; Orr, Bradford G; Banaszak Holl, Mark M; Andricioaei, Ioan

    2008-08-07

    The molecular structures and enthalpy release of poly(amidoamine) (PAMAM) dendrimers binding to 1,2-dimyristoyl- sn-glycero-3-phosphocholine (DMPC) bilayers were explored through atomistic molecular dynamics. Three PAMAM dendrimer terminations were examined: protonated primary amine, neutral acetamide, and deprotonated carboxylic acid. Fluid and gel lipid phases were examined to extract the effects of lipid tail mobility on the binding of generation-3 dendrimers, which are directly relevant to the nanoparticle interactions involving lipid rafts, endocytosis, lipid removal, and/or membrane pores. Upon binding to gel phase lipids, dendrimers remained spherical, had a constant radius of gyration, and approximately one-quarter of the terminal groups were in close proximity to the lipids. In contrast, upon binding to fluid phase bilayers, dendrimers flattened out with a large increase in their asphericity and radii of gyration. Although over twice as many dendrimer-lipid contacts were formed on fluid versus gel phase lipids, the dendrimer-lipid interaction energy was only 20% stronger. The greatest enthalpy release upon binding was between the charged dendrimers and the lipid bilayer. However, the stronger binding to fluid versus gel phase lipids was driven by the hydrophobic interactions between the inner dendrimer and lipid tails.

  4. The FIREBall-2 UV sample grating efficiency at 200-208nm

    Science.gov (United States)

    Quiret, S.; Milliard, B.; Grange, R.; Lemaitre, G. R.; Caillat, A.; Belhadi, M.; Cotel, A.

    2014-07-01

    The FIREBall-2 (Faint Intergalactic Redshifted Emission Balloon-2) is a balloon-borne ultraviolet spectro-imaging mission optimized for the study of faint diffuse emission around galaxies. A key optical component of the new spectrograph design is the high throughput cost-effective holographic 2400 ℓ =mm, 110x130mm aspherized reflective grating used in the range 200 - 208nm, near 28°deviation angle. In order to anticipate the efficiency in flight conditions, we have developed a PCGrate model for the FIREBall grating calibrated on linearly polarized measurements at 12° deviation angle in the range 240-350nm of a 50x50mm replica of the same master selected for the flight grating. This model predicts an efficiency within [64:7; 64:9]+/-0:7% (S polarization) and [38:3; 45]+/-2:2% (P-polarization) for the baseline aluminum coated grating with an Al2O3 natural oxidation layer and within [63:5; 65] +/-1% (S-polarization) and [51:3; 54:8] +/-2:8% (P-polarization) for an aluminum plus a 70nm MgF2 coating, in the range 200 - 208nm and for a 28°deviation angle. The model also shows there is room for significant improvements at shorter wavelengths, of interest for future deep UV spectroscopic missions.

  5. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Wei Kang; Denton, Alan R., E-mail: alan.denton@ndsu.edu [Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 (United States)

    2014-09-21

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments.

  6. The Phase-Induced Amplitude Apodization Coronagraph (PIAAC): Performance for Imaging of Earth-like Exoplanets.

    Science.gov (United States)

    Martinache, F.; Guyon, O.; Pluzhnik, E.; Ridgway, S.; Galicher, R.

    2004-12-01

    PIAA is one of the powerful applications of pupil remapping. A set of two aspheric mirrors changes the distribution of light and provides an apodized pupil, suitable for coronagraphy, without light loss on an absorbing mask. Deployed on to a space telescope with coronagraphic quality optics, it may allow planet detection from a 1.2 λ /d inner working distance and a full working field. We describe the performance of a PIAA version of NASA's Terrestrial Planet Finder (TPF) in terms of Signal to Noise Ratio and compare it to Classical Pupil Apodization (CPA) performance. We also discuss the necessity of using different occulting masks and give an estimate of the total exposure time for the planet detection phase of the TPF mission. This study is based on realistic Monte Carlo simulations of terrestrial planets orbiting around F, G, K stars within 30 pc around the solar system and includes planet phase and angular separation probabilities. This work was carried out under JPL contract numbers 1254445 and 1257767 for Development of Technologies for the Terrestrial Planet Finder Mission, with the support and hospitality of the National Astronomical Observatory of Japan.

  7. The Phase-Induced Amplitude Apodization Coronagraph (PIAAC): A High Performance Coronagraph for Exoplanet Imaging

    Science.gov (United States)

    Guyon, O.; Pluzhnik, E.; Martinache, F.; Ridgway, S.; Galicher, R.

    2004-12-01

    Using 2 aspheric mirrors, it is possible to achromatically apodize a telescope beam without losing light (Phase-Induced Amplitude Apodization, PIAA). We propose a coronagraph concept using this technique: the telescope pupil is first apodized to yield a high contrast focal plane image, on which an occulting mask is placed. The exit pupil is then de-apodized to regain a large field of view. We show that the PIAAC combines all the qualities needed for efficient exoplanet imaging: full throughput, small inner working angle (1.2 l/d), high angular resolution (l/d), low sensitivity to tip-tilt, and large field of view (more than 200 l/d in diameter). We conclude that PIAAC is well adapted for exoplanet imaging with a 4m to 6m space telescope (TPF mission). This work was carried out under JPL contract numbers 1254445 and 1257767 for Development of Technologies for the Terrestrial Planet Finder Mission, with the support and hospitality of the National Astronomical Observatory of Japan.

  8. The space instrument SOVAP of the PICARD mission

    Science.gov (United States)

    Conscience, C.; Meftah, M.; Chevalier, A.; Dewitte, S.; Crommelynck, D.,

    2011-09-01

    PICARD is a Satellite dedicated to the simultaneous measurement of the absolute total and spectral solar irradiance, the diameter and solar shape and the Sun's interior probed by helioseismology method. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. PICARD was launched on June 15, 2010. The Satellite was placed into the heliosynchronous orbit of 735 km with inclination of 98.28 degrees. The payload consists in two absolute radiometers measuring the TSI (Total Solar Irradiance) and an imaging telescope to determine the solar diameter, the limb shape and asphericity. SOVAP (SOlar VAriability Picard) is an experiment developed by the Belgian STCE (Solar Terrestrial Center of Excellence) with a contribution of the CNRS (Centre National de la Recherche Scientifique) composed of an absolute radiometer provided by the RMIB (Royal Meteorological Institute of Belgium) to measure the TSI and a bolometer provided by the ROB (Royal Observatory of Belgium). The continuous observation of the solar irradiance at the highest possible precision and accuracy is an important objective of the Earth climate change. This requires: high quality metrology in the space environment. In this article, we describe the SOVAP instrument, its performances and uncertainties on the measurements of the TSI.

  9. Development of micro-mirror slicer integral field unit for space-borne solar spectrographs

    Science.gov (United States)

    Suematsu, Yoshinori; Saito, Kosuke; Koyama, Masatsugu; Enokida, Yukiya; Okura, Yukinobu; Nakayasu, Tomoyasu; Sukegawa, Takashi

    2017-12-01

    We present an innovative optical design for image slicer integral field unit (IFU) and a manufacturing method that overcomes optical limitations of metallic mirrors. Our IFU consists of a micro-mirror slicer of 45 arrayed, highly narrow, flat metallic mirrors and a pseudo-pupil-mirror array of off-axis conic aspheres forming three pseudo slits of re-arranged slicer images. A prototype IFU demonstrates that the final optical quality is sufficiently high for a visible light spectrograph. Each slicer micro-mirror is 1.58 mm long and 30 μm wide with surface roughness ≤1 nm rms, and edge sharpness ≤ 0.1 μm, etc. This IFU is small size and can be implemented in a multi-slit spectrograph without any moving mechanism and fore optics, in which one slit is real and the others are pseudo slits from the IFU. The IFU mirrors were deposited by a space-qualified, protected silver coating for high reflectivity in visible and near IR wavelength regions. These properties are well suitable for space-borne spectrograph such as the future Japanese solar space mission SOLAR-C. We present the optical design, performance of prototype IFU, and space qualification tests of the silver coating.

  10. The Spatial Distribution of C2, C3, and NH in Comet 2P/Encke

    Science.gov (United States)

    Dorman, Garrett; Pierce, Donna M.; Cochran, Anita L.

    2013-12-01

    We examine the spatial distribution of C2, C3, and NH radicals in the coma of comet Encke in order to understand their abundances and distributions in the coma. The observations were obtained from 2003 October 22-24, using the 2.7 m telescope at McDonald Observatory. Building on our original study of CN and OH, we have used our modified version of the vectorial model, which treats the coma as one large cone, in order to reproduce Encke's highly aspherical and asymmetric coma. Our results suggest that NH can be explained by the photodissociation of NH2, assuming that NH2 is produced rapidly from NH3 in the innermost coma. Our modeling of C2 and C3 suggests a multi-generational photodissociation process may be required for their production. Using the results of our previous study, we also obtain abundance ratios with respect to OH and CN. Overall, we find that Encke exhibits typical carbon-chain abundances, and the results are consistent with other studies of comet Encke.

  11. Towards Forming a Primordial Protostar in a Cosmological AMR Simulation

    Science.gov (United States)

    Turk, Matthew J.; Abel, Tom; O'Shea, Brian W.

    2008-03-01

    Modeling the formation of the first stars in the universe is a well-posed problem and ideally suited for computational investigation.We have conducted high-resolution numerical studies of the formation of primordial stars. Beginning with primordial initial conditions appropriate for a ΛCDM model, we used the Eulerian adaptive mesh refinement code (Enzo) to achieve unprecedented numerical resolution, resolving cosmological scales as well as sub-stellar scales simultaneously. Building on the work of Abel, Bryan and Norman (2002), we followed the evolution of the first collapsing cloud until molecular hydrogen is optically thick to cooling radiation. In addition, the calculations account for the process of collision-induced emission (CIE) and add approximations to the optical depth in both molecular hydrogen roto-vibrational cooling and CIE. Also considered are the effects of chemical heating/cooling from the formation/destruction of molecular hydrogen. We present the results of these simulations, showing the formation of a 10 Jupiter-mass protostellar core bounded by a strongly aspherical accretion shock. Accretion rates are found to be as high as one solar mass per year.

  12. Highly accurate surface maps from profilometer measurements

    Science.gov (United States)

    Medicus, Kate M.; Nelson, Jessica D.; Mandina, Mike P.

    2013-04-01

    Many aspheres and free-form optical surfaces are measured using a single line trace profilometer which is limiting because accurate 3D corrections are not possible with the single trace. We show a method to produce an accurate fully 2.5D surface height map when measuring a surface with a profilometer using only 6 traces and without expensive hardware. The 6 traces are taken at varying angular positions of the lens, rotating the part between each trace. The output height map contains low form error only, the first 36 Zernikes. The accuracy of the height map is ±10% of the actual Zernike values and within ±3% of the actual peak to valley number. The calculated Zernike values are affected by errors in the angular positioning, by the centering of the lens, and to a small effect, choices made in the processing algorithm. We have found that the angular positioning of the part should be better than 1?, which is achievable with typical hardware. The centering of the lens is essential to achieving accurate measurements. The part must be centered to within 0.5% of the diameter to achieve accurate results. This value is achievable with care, with an indicator, but the part must be edged to a clean diameter.

  13. Development and Testing of an Air Fluorescence Imaging System for the Detection of Radiological Contamination

    International Nuclear Information System (INIS)

    Inrig, Elizabeth; Koslowsky, Vern; Andrews, Bob; Dick, Michael; Forget, Patrick; Ing, Harry; Hugron, Roger; Wong, Larry

    2011-01-01

    Detection of radionuclides emitting short-range radiation, such as α and low-energy β particles, has always presented a challenge, particularly when such radionuclides are dispersed over a wide area. In this situation, conventional detection methods require the area of interest to be surveyed using a fragile probe at very close range--a slow, error-prone, and potentially dangerous process that may take many hours for a single room. The instrument under development uses a novel approach by imaging radiation-induced fluorescence in the air surrounding a contaminated area, rather than detecting the radiation directly. A robust and portable system has been designed and built that will allow contaminated areas to be rapidly detected and delineated. The detector incorporates position-sensitive photo-multiplier tubes, UV filters, a fast electronic shutter and an aspherical phase mask that significantly increases the depth-of-field. Preliminary tests have been conducted using sealed 241 Am sources of varying activities and surface areas. The details of the instrument design will be described and the results of recent testing will be presented.

  14. Surgical correction of postoperative astigmatism

    Directory of Open Access Journals (Sweden)

    Lindstrom Richard

    1990-01-01

    Full Text Available The photokeratoscope has increased the understanding of the aspheric nature of the cornea as well as a better understanding of normal corneal topography. This has significantly affected the development of newer and more predictable models of surgical astigmatic correction. Relaxing incisions effectively flatten the steeper meridian an equivalent amount as they steepen the flatter meridian. The net change in spherical equivalent is, therefore, negligible. Poor predictability is the major limitation of relaxing incisions. Wedge resection can correct large degrees of postkeratoplasty astigmatism, Resection of 0.10 mm of tissue results in approximately 2 diopters of astigmatic correction. Prolonged postoperative rehabilitation and induced irregular astigmatism are limitations of the procedure. Transverse incisions flatten the steeper meridian an equivalent amount as they steepen the flatter meridian. Semiradial incisions result in two times the amount of flattening in the meridian of the incision compared to the meridian 90 degrees away. Combination of transverse incisions with semiradial incisions describes the trapezoidal astigmatic keratotomy. This procedure may correct from 5.5 to 11.0 diopters dependent upon the age of the patient. The use of the surgical keratometer is helpful in assessing a proper endpoint during surgical correction of astigmatism.

  15. Effect of pupil size on visual acuity in a laboratory model of pseudophakic monovision.

    Science.gov (United States)

    Kawamorita, Takushi; Uozato, Hiroshi; Handa, Tomoya; Ito, Misae; Shimizu, Kimiya

    2010-05-01

    To investigate the effect of pupil size on visual acuity in pseudophakic monovision. For the simulation, a modified Liou-Brennan model eye was used. The model eye was designed to include a centered optical system, corneal asphericity, an iris pupil, a Stiles-Crawford effect, an intraocular lens, and chromatic aberration. Calculation of the modulation transfer function (MTF) was performed with ZEMAX software. Visual acuity was estimated from the MTF and the retinal threshold curve. The sizes of the entrance pupil were 2.0, 2.5, 3.0, and 4.0 mm. Decreasing pupil diameter and increasing myopia progressively improved near visual acuity. For an entrance pupil size of 2.5 mm and a refractive error of -1.50 diopters, the logMAR value (Snellen; metric) in the non-dominant eye at 40 cm was 0.06 (20/23; 6/6.9). Knowledge of the patient's pupil diameter at near fixation can assist surgeons in determining the optimum degree of myopia for successful monovision.

  16. A portable non-contact displacement sensor and its application of lens centration error measurement

    Science.gov (United States)

    Yu, Zong-Ru; Peng, Wei-Jei; Wang, Jung-Hsing; Chen, Po-Jui; Chen, Hua-Lin; Lin, Yi-Hao; Chen, Chun-Cheng; Hsu, Wei-Yao; Chen, Fong-Zhi

    2018-02-01

    We present a portable non-contact displacement sensor (NCDS) based on astigmatic method for micron displacement measurement. The NCDS are composed of a collimated laser, a polarized beam splitter, a 1/4 wave plate, an aspheric objective lens, an astigmatic lens and a four-quadrant photodiode. A visible laser source is adopted for easier alignment and usage. The dimension of the sensor is limited to 115 mm x 36 mm x 56 mm, and a control box is used for dealing with signal and power control between the sensor and computer. The NCDS performs micron-accuracy with +/-30 μm working range and the working distance is constrained in few millimeters. We also demonstrate the application of the NCDS for lens centration error measurement, which is similar to the total indicator runout (TIR) or edge thickness difference (ETD) of a lens measurement using contact dial indicator. This application has advantage for measuring lens made in soft materials that would be starched by using contact dial indicator.

  17. Evolution of planetary nebulae. III. Position-velocity images of butterfly-type nebulae

    International Nuclear Information System (INIS)

    Icke, V.; Preston, H.L.; Balick, B.

    1989-01-01

    Observations of the motions of the shells of the planetary nebulae NGC 2346, NGC 2371-2, NGC 2440, NGC 6058, NGC 6210, IC 1747, IC 5217, J-320, and M2-9 are presented. These are all 'butterfly' type PNs, and show evidence for bipolar shocks. The observations are interpreted in terms of a fast spherical wind, driven by the central star into a quasi-toroidal envelope deposited earlier by the star, during its slow-wind phase on the asymptotic giant branch. It is shown that this model, which is a straightforward extension of a mechanism previously invoked to account for elliptical PNs, reproduces the essential kinematic features of butterfly PNs. It is inferred that the envelopes of butterflies must have a considerable equator-to-pole density gradient, and it is suggested that the origin of this asphericity must be sought in an as yet unknown mechanism during the AGB, Mira, or OH/IR phases of late stellar evolution. 28 references

  18. Spherical aberrations of human astigmatic corneas.

    Science.gov (United States)

    Zhao, Huawei; Dai, Guang-Ming; Chen, Li; Weeber, Henk A; Piers, Patricia A

    2011-11-01

    To evaluate whether the average spherical aberration of human astigmatic corneas is statistically equivalent to human nonastigmatic corneas. Spherical aberrations of 445 astigmatic corneas prior to laser vision correction were retrospectively investigated to determine Zernike coefficients for central corneal areas 6 mm in diameter using CTView (Sarver and Associates). Data were divided into groups according to cylinder power (0.01 to 0.25 diopters [D], 0.26 to 0.75 D, 0.76 to 1.06 D, 1.07 to 1.53 D, 1.54 to 2.00 D, and >2.00 D) and according to age by decade. Spherical aberrations were correlated with age and astigmatic power among groups and the entire population. Statistical analyses were conducted, and P.05 for all tested groups). Mean spherical aberration of astigmatic corneas was not correlated significantly with cylinder power or age (P>.05). Spherical aberrations are similar to those of nonastigmatic corneas, permitting the use of these additional data in the design of aspheric toric intra-ocular lenses. Copyright 2011, SLACK Incorporated.

  19. Desempenho visual de lentes de contato gelatinosas de diferentes tipos baseado na análise de frentes de onda Optical performance of different soft contact lenses based on wavefront analysis

    Directory of Open Access Journals (Sweden)

    Roberta Fagnani Gatti

    2008-12-01

    Full Text Available OBJETIVOS: Avaliar e comparar o desempenho visual, por meio da análise de frentes de onda, de seis diferentes tipos de lentes de contato gelatinosas [Cooperflex® (Coopervision, Frequency® 55 Aspheric (Coopervision, World Vision FW® (World Vision, Pure Vision® (Bausch & Lomb, Focus® Monthly (Ciba Vision, Focus® Choice AB (Ciba Vision]. MÉTODOS: Realizou-se estudo prospectivo em amostra constituída por 130 olhos de 71 indivíduos portadores de miopia ou hipermetropia até 6,00D e astigmatismo até 1,50D, com acuidade visual corrigida com óculos igual ou superior a 20/20. Os sujeitos foram inicialmente submetidos ao exame clínico oftalmológico e posteriormente, ao exame de análise de frentes de onda com o aberrômetro LADARWave® (Alcon, em duas condições: sem correção óptica e em uso de um dos tipos de lente de contato incluídos no estudo, com grau correspondente ao equivalente esférico do paciente e corrigido pela distância vértice. Para análise de resultados os indivíduos foram divididos em seis grupos similares, sendo testado em cada grupo um dos tipos de lente incluídos no estudo. RESULTADOS: Mudanças nos valores das aberrações de alta ordem foram verificadas durante uso das lentes de contato. De 130 olhos estudados, 78 apresentaram aumento no valor de RMS total durante o uso da lente. Os seis tipos de lente estudados demonstraram tendência ao aumento no valor médio de RMS total durante seu uso, sem diferença estatisticamente significante entre as mesmas. O estudo demonstrou tendência ao aumento no valor médio das aberrações tipo "coma" durante o uso das lentes. As lentes Frequency® Aspheric e Cooperflex® apresentaram melhor desempenho visual em relação ao "coma". O estudo demonstrou tendência à diminuição no valor médio das aberrações esféricas durante o uso das lentes, sendo esta tendência maior nos pacientes míopes em relação aos hipermétropes. Foi demonstrado tendência ao aumento no

  20. Development of the measurement system with interferometers for ultraprecise X-ray mirror

    CERN Document Server

    Yamauchi, K; Mimura, H

    2003-01-01

    A figure measurement system with a stitching method has been developed for evaluation and fabrication of the ultraprecise hard X-ray mirror optics. This system was constructed by two interferometers. One is the Michelson-type microscopic interferometer which is improved to keep the focus distance within 0.1 mu m. Another is the Fizeau's interferometer employed to compensate stitching error in the long spatial wavelength range. To estimate the absolute accuracy in this figure measurement system, the reflection X-ray intensity distributions of flat and aspherical mirrors, which are fabricated by us, were predicted by wave-optical simulation based on measured profile an compared with actually observed distributions. As the result, they are in good agreements. These agreements prove that the developed system has sub-nanometer absolute accuracy in all the spatial wavelength range longer than 0.5mm, because sub-nanometer figure error in those spatial wavelength ranges are known to affect reflection X-ray intensity ...

  1. Jamming of soft particles: geometry, mechanics, scaling and isostaticity

    Energy Technology Data Exchange (ETDEWEB)

    Van Hecke, M, E-mail: mvhecke@physics.leidenuniv.n [Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden (Netherlands)

    2010-01-27

    Amorphous materials as diverse as foams, emulsions, colloidal suspensions and granular media can jam into a rigid, disordered state where they withstand finite shear stresses before yielding. Here we review the current understanding of the transition to jamming and the nature of the jammed state for disordered packings of particles that act through repulsive contact interactions and are at zero temperature and zero shear stress. We first discuss the breakdown of affine assumptions that underlies the rich mechanics near jamming. We then extensively discuss jamming of frictionless soft spheres. At the jamming point, these systems are marginally stable (isostatic) in the sense of constraint counting, and many geometric and mechanical properties scale with distance to this jamming point. Finally, we discuss current explorations of jamming of frictional and non-spherical (ellipsoidal) particles. Both friction and asphericity tune the contact number at jamming away from the isostatic limit, but in opposite directions. This allows one to disentangle the distance to jamming and the distance to isostaticity. The picture that emerges is that most quantities are governed by the contact number and scale with the distance to isostaticity, while the contact number itself scales with the distance to jamming. (topical review)

  2. Polymer Crowding in Confined Polymer-Nanoparticle Mixtures

    Science.gov (United States)

    Davis, Wyatt J.; Denton, Alan R.

    Crowding can influence the conformations and thus functionality of macromolecules in quasi-two-dimensional environments, such as DNA or proteins confined to a cell membrane. We explore such crowding within a model of polymers as penetrable ellipses, whose shapes are governed by the statistics of a 2D random walk. The principal radii of the polymers fluctuate according to probability distributions of the eigenvalues of the gyration tensor. Within this coarse-grained model, we perform Monte Carlo simulations of mixtures of polymers and hard nanodisks, including trial changes in polymer conformation (shape and orientation). Penetration of polymers by nanodisks is incorporated with a free energy cost predicted by polymer field theory. Over ranges of size ratio and nanodisk density, we analyze the influence of crowding on polymer shape by computing eigenvalue distributions, mean radius of gyration, and mean asphericity of the polymer. We compare results with predictions of free-volume theory and with corresponding results in three dimensions. Our approach may help to interpret recent (and motivate future) experimental studies of biopolymers interacting with cell membranes, with relevance for drug delivery and gene therapy. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

  3. Post-seismic relaxation theory on laterally heterogeneous viscoelastic model

    Science.gov (United States)

    Pollitz, F.F.

    2003-01-01

    Investigation was carried out into the problem of relaxation of a laterally heterogeneous viscoelastic Earth following an impulsive moment release event. The formal solution utilizes a semi-analytic solution for post-seismic deformation on a laterally homogeneous Earth constructed from viscoelastic normal modes, followed by application of mode coupling theory to derive the response on the aspherical Earth. The solution is constructed in the Laplace transform domain using the correspondence principle and is valid for any linear constitutive relationship between stress and strain. The specific implementation described in this paper is a semi-analytic discretization method which assumes isotropic elastic structure and a Maxwell constitutive relation. It accounts for viscoelastic-gravitational coupling under lateral variations in elastic parameters and viscosity. For a given viscoelastic structure and minimum wavelength scale, the computational effort involved with the numerical algorithm is proportional to the volume of the laterally heterogeneous region. Examples are presented of the calculation of post-seismic relaxation with a shallow, laterally heterogeneous volume following synthetic impulsive seismic events, and they illustrate the potentially large effect of regional 3-D heterogeneities on regional deformation patterns.

  4. Polymer crowding and shape distributions in polymer-nanoparticle mixtures

    International Nuclear Information System (INIS)

    Lim, Wei Kang; Denton, Alan R.

    2014-01-01

    Macromolecular crowding can influence polymer shapes, which is important for understanding the thermodynamic stability of polymer solutions and the structure and function of biopolymers (proteins, RNA, DNA) under confinement. We explore the influence of nanoparticle crowding on polymer shapes via Monte Carlo simulations and free-volume theory of a coarse-grained model of polymer-nanoparticle mixtures. Exploiting the geometry of random walks, we model polymer coils as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor. Accounting for the entropic cost of a nanoparticle penetrating a larger polymer coil, we compute the crowding-induced shift in the shape distributions, radius of gyration, and asphericity of ideal polymers in a theta solvent. With increased nanoparticle crowding, we find that polymers become more compact (smaller, more spherical), in agreement with predictions of free-volume theory. Our approach can be easily extended to nonideal polymers in good solvents and used to model conformations of biopolymers in crowded environments

  5. Optical concentrators for Čerenkov light detector

    CERN Document Server

    Kramer, Daniel

    2005-01-01

    RICH1 (Ring Imaging Cherenkov) detector is an important part of COMPASS particle physics experiment in CERN. Its central area photon detection part is being upgraded from wire chambers with CsI layers to very fast UV extended Hamamatsu MAPMTs (Multi Anode Photo Multiplier Tubes) array. MAPMTs have approx. 3 times smaller active area than the covered region, thus optical concentrators transforming image from old system focal plane to the new photocathode were needed. System was expected to be efficient from 200 to 600nm with best performance at 300nm and with angular acceptance including all interesting physics processes. Several design types (including i.e. a hollow waveguide) were investigated and the “telescopic” two lens aspherical design concept was selected for its proven functionality in HERA-B experiment. Chosen material was UV grade fused silica. System consists of a field lens placed in the focal plane of the RICH mirrors and a condenser lens downstream. Designing procedure started with a high op...

  6. Optical design of ultrashort throw liquid crystal on silicon projection system

    Science.gov (United States)

    Huang, Jiun-Woei

    2017-05-01

    An ultrashort throw liquid crystal on silicon (LCoS) projector for home cinema, virtual reality, and automobile heads-up display has been designed and fabricated. To achieve the best performance and highest-quality image, this study aimed to design wide-angle projection optics and optimize the illumination for LCoS. Based on the telecentric lens projection system and optimized Koehler illumination, the optical parameters were calculated. The projector's optical system consisted of a conic aspheric mirror and image optics using either symmetric double Gauss or a large-angle eyepiece to achieve a full projection angle larger than 155 deg. By applying Koehler illumination, image resolution was enhanced and the modulation transfer function of the image in high spatial frequency was increased to form a high-quality illuminated image. The partial coherence analysis verified that the design was capable of 2.5 lps/mm within a 2 m×1.5 m projected image. The throw ratio was less than 0.25 in HD format.

  7. Transethosomal gels as carriers for the transdermal delivery of colchicine: statistical optimization, characterization, and ex vivo evaluation.

    Science.gov (United States)

    Abdulbaqi, Ibrahim M; Darwis, Yusrida; Assi, Reem Abou; Khan, Nurzalina Abdul Karim

    2018-01-01

    Colchicine is used for the treatment of gout, pseudo-gout, familial Mediterranean fever, and many other illnesses. Its oral administration is associated with poor bioavailability and severe gastrointestinal side effects. The drug is also known to have a low therapeutic index. Thus to overcome these drawbacks, the transdermal delivery of colchicine was investigated using transethosomal gels as potential carriers. Colchicine-loaded transethosomes (TEs) were prepared by the cold method and statistically optimized using three sets of 24 factorial design experiments. The optimized formulations were incorporated into Carbopol 940 ® gel base. The prepared colchicine-loaded transethosomal gels were further characterized for vesicular size, dispersity, zeta potential, drug content, pH, viscosity, yield, rheological behavior, and ex vivo skin permeation through Sprague Dawley rats' back skin. The results showed that the colchicine-loaded TEs had aspherical irregular shape, nanometric size range, and high entrapment efficiency. All the formulated gels exhibited non-Newtonian plastic flow without thixotropy. Colchicine-loaded transethosomal gels were able to significantly enhance the skin permeation parameters of the drug in comparison to the non-ethosomal gel. These findings suggested that the transethosomal gels are promising carriers for the transdermal delivery of colchicine, providing an alternative route for drug administration.

  8. Scientific Performance Analysis of the SYZ Telescope Design versus the RC Telescope Design

    Science.gov (United States)

    Ma, Donglin; Cai, Zheng

    2018-02-01

    Recently, Su et al. propose an innovative design, referred as the “SYZ” design, for China’s new project of a 12 m optical-infrared telescope. The SYZ telescope design consists of three aspheric mirrors with non-zero power, including a relay mirror below the primary mirror. SYZ design yields a good imaging quality and has a relatively flat field curvature at Nasmyth focus. To evaluate the science-compatibility of this three-mirror telescope, in this paper, we thoroughly compare the performance of SYZ design with that of Ritchey–Chrétien (RC) design, a conventional two-mirror telescope design. Further, we propose the Observing Information Throughput (OIT) as a metric for quantitatively evaluating the telescopes’ science performance. We find that although a SYZ telescope yields a superb imaging quality over a large field of view, a two-mirror (RC) telescope design holds a higher overall throughput, a better diffraction-limited imaging quality in the central field of view (FOV < 5‧) which is better for the performance of extreme Adaptive Optics (AO), and a generally better scientific performance with a higher OIT value. D. Ma & Z. Cai contributed equally to this paper.

  9. Contributions of charge-density research to medicinal chemistry

    Directory of Open Access Journals (Sweden)

    Birger Dittrich

    2014-11-01

    Full Text Available This article reviews efforts in accurate experimental charge-density studies with relevance to medicinal chemistry. Initially, classical charge-density studies that measure electron density distribution via least-squares refinement of aspherical-atom population parameters are summarized. Next, interaction density is discussed as an idealized situation resembling drug–receptor interactions. Scattering-factor databases play an increasing role in charge-density research, and they can be applied both to small-molecule and macromolecular structures in refinement and analysis; software development facilitates their use. Therefore combining both of these complementary branches of X-ray crystallography is recommended, and examples are given where such a combination already proved useful. On the side of the experiment, new pixel detectors are allowing rapid measurements, thereby enabling both high-throughput small-molecule studies and macromolecular structure determination to higher resolutions. Currently, the most ambitious studies compute intermolecular interaction energies of drug–receptor complexes, and it is recommended that future studies benefit from recent method developments. Selected new developments in theoretical charge-density studies are discussed with emphasis on its symbiotic relation to crystallography.

  10. Subjective evaluation of uncorrected vision in patients undergoing cataract surgery with (diffractive multifocal lenses and monovision

    Directory of Open Access Journals (Sweden)

    Stock RA

    2017-07-01

    Full Text Available Ricardo Alexandre Stock, Thaís Thumé, Luan Gabriel Paese, Elcio Luiz Bonamigo Universidade do Oeste de Santa Catarina, Rua Getúlio Vargas, Joaçaba, Santa Catarina, Brazil Purpose: To analyze patient satisfaction and difficulties with bilateral multifocal intraocular lenses (IOLs implantation and aspheric monofocal IOLs implantation using monovision, after cataract surgery.Materials and methods: A total of 61 participants were included in the study, 29 with monovision and 32 with multifocal lenses. The inclusion criteria were patients undergoing phacoemulsification for bilateral visual impairment due to cataracts and presenting with postoperative visual acuity of 20/30 or better for distance and line J3 or better for near vision.Results: The 2 groups had similar results regarding difficulties with daily activities such as distance vision, near vision, watching television, reading, cooking, using a computer or cellphone, shaving/putting on makeup and shopping. There were differences in responses between the groups regarding difficulty with night vision (P=0.0565 and night driving (P=0.0291. Degree of satisfaction in terms of distance vision without glasses was statistically significantly better in monovision group (P=0.0332, but not for near (P=0.9101.Conclusion: Both techniques yielded satisfactory results regarding visual acuity for different activities without the need to use glasses. Multifocal lenses are a good option for patients with the exception of night driving, and who desire independence from glasses. Keywords: cataract extraction, aphakia, postcataract, patient satisfaction, night vision

  11. Conversion of radius of curvature to power (and vice versa)

    Science.gov (United States)

    Wickenhagen, Sven; Endo, Kazumasa; Fuchs, Ulrike; Youngworth, Richard N.; Kiontke, Sven R.

    2015-09-01

    Manufacturing optical components relies on good measurements and specifications. One of the most precise measurements routinely required is the form accuracy. In practice, form deviation from the ideal surface is effectively low frequency errors, where the form error most often accounts for no more than a few undulations across a surface. These types of errors are measured in a variety of ways including interferometry and tactile methods like profilometry, with the latter often being employed for aspheres and general surface shapes such as freeforms. This paper provides a basis for a correct description of power and radius of curvature tolerances, including best practices and calculating the power value with respect to the radius deviation (and vice versa) of the surface form. A consistent definition of the sagitta is presented, along with different cases in manufacturing that are of interest to fabricators and designers. The results make clear how the definitions and results should be documented, for all measurement setups. Relationships between power and radius of curvature are shown that allow specifying the preferred metric based on final accuracy and measurement method. Results shown include all necessary equations for conversion to give optical designers and manufacturers a consistent and robust basis for decision-making. The paper also gives guidance on preferred methods for different scenarios for surface types, accuracy required, and metrology methods employed.

  12. Transethosomal gels as carriers for the transdermal delivery of colchicine: statistical optimization, characterization, and ex vivo evaluation

    Directory of Open Access Journals (Sweden)

    Abdulbaqi IM

    2018-04-01

    Full Text Available Ibrahim M Abdulbaqi, Yusrida Darwis, Reem Abou Assi, Nurzalina Abdul Karim Khan School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia Introduction: Colchicine is used for the treatment of gout, pseudo-gout, familial Mediterranean fever, and many other illnesses. Its oral administration is associated with poor bioavailability and severe gastrointestinal side effects. The drug is also known to have a low therapeutic index. Thus to overcome these drawbacks, the transdermal delivery of colchicine was investigated using transethosomal gels as potential carriers.Methods: Colchicine-loaded transethosomes (TEs were prepared by the cold method and statistically optimized using three sets of 24 factorial design experiments. The optimized formulations were incorporated into Carbopol 940® gel base. The prepared colchicine-loaded transethosomal gels were further characterized for vesicular size, dispersity, zeta potential, drug content, pH, viscosity, yield, rheological behavior, and ex vivo skin permeation through Sprague Dawley rats’ back skin.Results: The results showed that the colchicine-loaded TEs had aspherical irregular shape, nanometric size range, and high entrapment efficiency. All the formulated gels exhibited non-Newtonian plastic flow without thixotropy. Colchicine-loaded transethosomal gels were able to significantly enhance the skin permeation parameters of the drug in comparison to the non-ethosomal gel.Conclusion: These findings suggested that the transethosomal gels are promising carriers for the transdermal delivery of colchicine, providing an alternative route for drug administration. Keywords: transethosomes, ethosomal nanocarriers, colchicine, factorial design, skin permeation, rheology

  13. Effect of process control agent on the structural and magnetic properties of nano/amorphous Fe0.7Nb0.1Zr0.1Ti0.1 powders prepared by high energy ball milling

    Science.gov (United States)

    Khazaei Feizabad, Mohammad Hossein; Sharafi, Shahriar; Khayati, Gholam Reza; Ranjbar, Mohammad

    2018-03-01

    In this study, amorphous Fe0.7Nb0.1Zr0.1Ti0.1 alloy without metalloids was produced by mechanical alloying of pure mixture elements. Miedema's semi-empirical model was employed to predict the possibility of amorphous phase formation in proposed alloying system. The effect of Hexane as process control agent (PCA) on the structural, magnetic, morphological and thermal properties of the products was investigated. The results showed that the presence of PCA was necessary for the formation of amorphous phase as well as improved its soft magnetic properties. The PCA addition causes an increase of the saturation magnetization (about 43%) and decrease of the coercivity (about 50%). Moreover, the sample milled without PCA, showed a wide particle size distribution as well as relatively spherical geometry. While, in the presence of PCA the powders were aspherical and Polygon. In addition, the crystallization and Curie temperatures were found to be around 800 °C and 650 °C, respectively which are relatively high values for these kinds of alloys.

  14. ON THE CLUSTER PHYSICS OF SUNYAEV-ZEL'DOVICH AND X-RAY SURVEYS. II. DECONSTRUCTING THE THERMAL SZ POWER SPECTRUM

    International Nuclear Information System (INIS)

    Battaglia, N.; Bond, J. R.; Pfrommer, C.; Sievers, J. L.

    2012-01-01

    Secondary anisotropies in the cosmic microwave background are a treasure-trove of cosmological information. Interpreting current experiments probing them are limited by theoretical uncertainties rather than by measurement errors. Here we focus on the secondary anisotropies resulting from the thermal Sunyaev-Zel'dovich (tSZ) effect; the amplitude of which depends critically on the average thermal pressure profile of galaxy groups and clusters. To this end, we use a suite of hydrodynamical TreePM-SPH simulations that include radiative cooling, star formation, supernova feedback, and energetic feedback from active galactic nuclei. We examine in detail how the pressure profile depends on cluster radius, mass, and redshift and provide an empirical fitting function. We employ three different approaches for calculating the tSZ power spectrum: an analytical approach that uses our pressure profile fit, a semianalytical method of pasting our pressure fit onto simulated clusters, and a direct numerical integration of our simulated volumes. We demonstrate that the detailed structure of the intracluster medium and cosmic web affect the tSZ power spectrum. In particular, the substructure and asphericity of clusters increase the tSZ power spectrum by 10%-20% at l ∼ 2000-8000, with most of the additional power being contributed by substructures. The contributions to the power spectrum from radii larger than R 500 is ∼20% at l = 3000, thus clusters interiors (r 500 ) dominate the power spectrum amplitude at these angular scales.

  15. ON THE CLUSTER PHYSICS OF SUNYAEV-ZEL'DOVICH AND X-RAY SURVEYS. II. DECONSTRUCTING THE THERMAL SZ POWER SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St George, Toronto, ON M5S 3H4 (Canada); Bond, J. R.; Pfrommer, C.; Sievers, J. L. [Canadian Institute for Theoretical Astrophysics, 60 St George, Toronto, ON M5S 3H8 (Canada)

    2012-10-20

    Secondary anisotropies in the cosmic microwave background are a treasure-trove of cosmological information. Interpreting current experiments probing them are limited by theoretical uncertainties rather than by measurement errors. Here we focus on the secondary anisotropies resulting from the thermal Sunyaev-Zel'dovich (tSZ) effect; the amplitude of which depends critically on the average thermal pressure profile of galaxy groups and clusters. To this end, we use a suite of hydrodynamical TreePM-SPH simulations that include radiative cooling, star formation, supernova feedback, and energetic feedback from active galactic nuclei. We examine in detail how the pressure profile depends on cluster radius, mass, and redshift and provide an empirical fitting function. We employ three different approaches for calculating the tSZ power spectrum: an analytical approach that uses our pressure profile fit, a semianalytical method of pasting our pressure fit onto simulated clusters, and a direct numerical integration of our simulated volumes. We demonstrate that the detailed structure of the intracluster medium and cosmic web affect the tSZ power spectrum. In particular, the substructure and asphericity of clusters increase the tSZ power spectrum by 10%-20% at l {approx} 2000-8000, with most of the additional power being contributed by substructures. The contributions to the power spectrum from radii larger than R {sub 500} is {approx}20% at l = 3000, thus clusters interiors (r < R {sub 500}) dominate the power spectrum amplitude at these angular scales.

  16. Complex structure of the lithospheric slab beneath the Banda arc, eastern Indonesia depicted by a seismic tomographic model

    Directory of Open Access Journals (Sweden)

    Sri Widiyantoro

    2011-10-01

    Full Text Available Seismic tomography with a non-linear approach has been successfully applied to image the P-wave velocity structure beneath the Banda arc in detail. Nearly one million compressional phases including the surfacereflected depth phases pP and pwP from events within the Indonesian region have been used. The depth phases have been incorporated in order to improve the sampling of the uppermantle structure, particularly below the Banda Sea in the back-arc regions. For the model parameterization, we have combined a highresolution regional inversion with a low-resolution global inversion to allow detailed images of slab structures within the study region and to minimize the mapping of distant aspherical mantle structure into the volume under study. In this paper, we focus our discussion on the upper mantle and transition zone structure beneath the curved Banda arc. The tomographic images confirm previous observations of the twisting of the slab in the upper mantle, forming a spoon-shaped structure beneath the Banda arc. A slab lying flat on the 660 km discontinuity beneath the Banda Sea is also well imaged. Further interpretations of the resulting tomograms and seismicity data support the scenario of the Banda arc subduction rollback.

  17. Development of the water window imaging x-ray microscope

    International Nuclear Information System (INIS)

    Hoover, R.B.; Shealy, D.L.; Baker, P.C.; Barbee, T.W. Jr.; Walker, A.B.C. Jr.

    1991-01-01

    This paper reports on the Water Window Imaging X-ray Microscopy which is currently being developed by a consortium from the Marshall Space Flight Center, the University of Alabama at Birmingham, Baker Consulting, the Lawrence Livermore National Laboratory, and Stanford University. The high quality solar images achieved during the Stanford/MSFC/LLNL Rocket X-ray Spectroheliograph flight conclusively established that excellent imaging could be obtained with doubly reflecting multilayer optical systems. Theoretical studies carried out as part of the MSFC X-ray Microscopy Program, demonstrated that high quality, high resolution multilayer x-ray imaging microscopes could be achieved with spherical optics in the Schwarzschild configuration and with Aspherical optical systems. Advanced Flow Polishing methods have been used to fabricate substrates for multilayer optics. On hemlite grade Sapphire, the authors have achieved microscopy mirror substrates on concave and convex spherical surfaces with 0.5 Angstrom rms surface smoothness, as measured by the Zygo profilometer. In this paper the authors report on the current status of fabrication and testing of the optical and mechanical subsystems for the Water Window Imaging X-ray Microscope

  18. Production of the 4.1-m Zerodur mirror blank for the VISTA Telescope

    Science.gov (United States)

    Doehring, Thorsten; Jedamzik, Ralf; Wittmer, Volker; Thomas, Armin

    2004-09-01

    VISTA (Visible and Infrared Survey Telescope for Astronomy) is designed to be the world's largest wide field telescope. After finishing of the construction the telescope will be part of ESO and located in Chile close to the VLT observatory at Cerro Paranal. In November 2001 SCHOTT was selected by the VISTA project office at the Royal Observatory of Edinburgh to deliver the 4.1 m diameter primary mirror blank. The manufacturing of the mirror blank made from the zero expansion material Zerodur was challenging especially due to the f/1 design. Several tons of the glass ceramic material were removed during the grinding operation. A meniscus blank with a diameter of 4100 mm and a thickness of 171.5 mm was generated, having a large central hole of 1200 mm and an aspherical shape of the concave surface. Also the handling and turning operations needed special effort and were performed by a skilled team. This paper presents details and pictures of the corresponding production and inspection sequence at SCHOTT. The geometrical parameters were measured during manufacturing by help of a laser tracker system and the achieved parameters were compared with the initial technical specification. The final quality inspection verified the excellent quality of the mirror blank. The close co-operation between the astronomers and industry resulted in a project management without problems. In April 2003 the VISTA blank was delivered successfully within a ceremony dedicated to the anniversary of "100 years of astronomical mirror blanks from SCHOTT."

  19. Diamond Turning Of Infra-Red Components

    Science.gov (United States)

    Hodgson, B.; Lettington, A. H.; Stillwell, P. F. T. C.

    1986-05-01

    Single point diamond machining of infra-red optical components such as aluminium mirrors, germanium lenses and zinc sulphide domes is potentially the most cost effective method for their manufacture since components may be machined from the blanks to a high surface finish, requiring no subsequent polishing, in a few minutes. Machines for the production of flat surfaces are well established. Diamond turning lathes for curved surfaces however require a high capital investment which can be justified only for research purposes or high volume production. The present paper describes the development of a low cost production machine based on a Bryant Symons diamond turning lathe which is able to machine spherical components to the required form and finish. It employs two horizontal spindles one for the workpiece the other for the tool. The machined radius of curvature is set by the alignment of the axes and the radius of the tool motion, as in conventional generation. The diamond tool is always normal to the workpiece and does not need to be accurately profiled. There are two variants of this basic machine. For machining hemispherical domes the axes are at right angles while for lenses with positive or negative curvature these axes are adjustable. An aspherical machine is under development, based on the all mechanical spherical machine, but in which a ± 2 mm aspherecity may be imposed on the best fit sphere by moving the work spindle under numerical control.

  20. Lens Dk/t influences the clinical response in overnight orthokeratology.

    Science.gov (United States)

    Lum, Edward; Swarbrick, Helen A

    2011-04-01

    To investigate the influence of lens oxygen transmissibility (Dk/t) on the clinical response to overnight (ON) orthokeratology (OK) lens wear over 2 weeks. Eleven subjects (age, 20 to 39 years) were fitted with OK lenses (BE; Capricornia Contact Lens) in both eyes. Lenses in matched design/fitting but different materials (Boston EO and XO; nominal Dk/t: 26 and 46 ISO Fatt, respectively) were worn ON only in the two eyes over a 2-week period. Changes in logarithm of the minimum angle of resolution visual acuity, subjective refraction (spherical equivalent), corneal apical radius ro and asphericity Q (Medmont E300), and central stromal thickness (Holden-Payor optical pachometer) were measured. There were statistically significant differences in outcomes between the two lens materials (analysis of variance, p 0.05). An increase in lens Dk/t appears to increase the clinical effects of ON reverse-geometry lens wear over the medium term. This adds further support to the recommendation that high Dk materials should be used for ON OK not only to provide physiological advantages but also to optimize clinical outcomes.

  1. New vistas in refractive laser beam shaping with an analytic design approach

    Science.gov (United States)

    Duerr, Fabian; Thienpont, Hugo

    2014-05-01

    Many commercial, medical and scientific applications of the laser have been developed since its invention. Some of these applications require a specific beam irradiance distribution to ensure optimal performance. Often, it is possible to apply geometrical methods to design laser beam shapers. This common design approach is based on the ray mapping between the input plane and the output beam. Geometric ray mapping designs with two plano-aspheric lenses have been thoroughly studied in the past. Even though analytic expressions for various ray mapping functions do exist, the surface profiles of the lenses are still calculated numerically. In this work, we present an alternative novel design approach that allows direct calculation of the rotational symmetric lens profiles described by analytic functions. Starting from the example of a basic beam expander, a set of functional differential equations is derived from Fermat's principle. This formalism allows calculating the exact lens profiles described by Taylor series coefficients up to very high orders. To demonstrate the versatility of this new approach, two further cases are solved: a Gaussian to at-top irradiance beam shaping system, and a beam shaping system that generates a more complex dark-hollow Gaussian (donut-like) irradiance profile with zero intensity in the on-axis region. The presented ray tracing results confirm the high accuracy of all calculated solutions and indicate the potential of this design approach for refractive beam shaping applications.

  2. Automatic centroid detection and surface measurement with a digital Shack–Hartmann wavefront sensor

    International Nuclear Information System (INIS)

    Yin, Xiaoming; Zhao, Liping; Li, Xiang; Fang, Zhongping

    2010-01-01

    With the breakthrough of manufacturing technologies, the measurement of surface profiles is becoming a big issue. A Shack–Hartmann wavefront sensor (SHWS) provides a promising technology for non-contact surface measurement with a number of advantages over interferometry. The SHWS splits the incident wavefront into many subsections and transfers the distorted wavefront detection into the centroid measurement. So the accuracy of the centroid measurement determines the accuracy of the SHWS. In this paper, we have presented a new centroid measurement algorithm based on an adaptive thresholding and dynamic windowing method by utilizing image-processing techniques. Based on this centroid detection method, we have developed a digital SHWS system which can automatically detect centroids of focal spots, reconstruct the wavefront and measure the 3D profile of the surface. The system has been tested with various simulated and real surfaces such as flat surfaces, spherical and aspherical surfaces as well as deformable surfaces. The experimental results demonstrate that the system has good accuracy, repeatability and immunity to optical misalignment. The system is also suitable for on-line applications of surface measurement

  3. Does the foveal shape influence the image formation in human eyes?

    Science.gov (United States)

    Frey, Katharina; Zimmerling, Beatrice; Scheibe, Patrick; Rauscher, Franziska G.; Reichenbach, Andreas; Francke, Mike; Brunner, Robert

    2017-10-01

    In human eyes, the maximum visual acuity correlates locally with the fovea, a shallow depression in the retina. Previous examinations have been reduced to simple geometrical fovea models derived from postmortem preparations and considering only a few superficial ray propagation aspects. In the current study, an extended and realistic analysis of ray-optical simulations for a comprehensive anatomical realistic eye model for the anterior part and realistic aspherical human foveal topographical profiles deduced from in vivo optical coherence tomography (OCT) are presented, and the refractive index step at the transition from vitreous to retinal tissue is taken into account. The optical effect of a commonly shaped (averaged) and an extraordinarily shaped foveal pit were both compared to the analysis of an assumed pure spherical boundary layer. The influence of the aperture size, wavelength, and incident angle on the spot size and shape, as well as the axial focal and lateral centroid position is investigated, and a lateral displacement of about 2 μm and an axial shift of the best focal position of less than 4 μm are found. These findings indicate only small optical effects that are laterally in the range of inter-receptor distances and axially less than the photoreceptor outer segment dimension.

  4. Towards gravitational-wave astronomy of core-collapse supernova explosion

    International Nuclear Information System (INIS)

    Kotake, Kei

    2010-01-01

    We study properties of gravitational waves based on the three-dimensional (3D) simulations, which demonstrate the neutrino-driven explosions aided by the standing accretion shock instability (SASI). Pushed by evidence supporting slow rotation prior to core-collapse, we focus on the asphericities in neutrino emissions and matter motions outside the protoneutron star. By performing a ray-tracing calculation in 3D, we estimate accurately the gravitational waveforms from anisotropic neutrino emissions. In contrast to the previous work assuming axisymmetry, we find that the gravitational waveforms vary much more stochastically because the explosion anisotropies depend sensitively on the growth of the SASI which develops chaotically in all directions. Our results show that the gravitational-wave spectrum has its peak near ∼ 100 Hz, reflecting the SASI-induced matter overturns of ∼ O(10) ms. We point out that the detection of such signals, possibly visible to the LIGO-class detectors for a Galactic supernova, could be an important probe into the long-veiled explosion mechanism.

  5. STOCHASTIC NATURE OF GRAVITATIONAL WAVES FROM SUPERNOVA EXPLOSIONS WITH STANDING ACCRETION SHOCK INSTABILITY

    International Nuclear Information System (INIS)

    Kotake, Kei; Iwakami, Wakana; Ohnishi, Naofumi; Yamada, Shoichi

    2009-01-01

    We study the properties of gravitational waves (GWs) based on three-dimensional (3D) simulations, which demonstrate neutrino-driven explosions aided by standing accretion shock instability (SASI). Pushed by evidence supporting slow rotation prior to core collapse, we focus on the asphericities in neutrino emissions and matter motions outside the protoneutron star. By performing a ray-tracing calculation in 3D, we estimate accurately the gravitational waveforms from anisotropic neutrino emissions. In contrast to the previous work assuming axisymmetry, we find that the gravitational waveforms vary much more stochastically because the explosion anisotropies depend sensitively on the growth of SASI which develops chaotically in all directions. Our results show that the GW spectrum has its peak near ∼100 Hz, reflecting SASI-induced matter overturns of ∼O(10) ms. We point out that the detection of such signals, possibly visible to the LIGO-class detectors for a Galactic supernova, could be an important probe into the long-veiled explosion mechanism.

  6. Explosive nucleosynthesis in a neutrino-driven core collapse supernova

    International Nuclear Information System (INIS)

    Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2010-01-01

    We investigate explosive nucleosynthesis in a delayed neutrino-driven, supernova explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of a 15 M · star. We take into accounts neutrino heating and cooling as well as change in electron fraction due to weak interactions appropriately, in the two-dimensional simulations. We assume the isotropic emission of neutrinos from the neutrino spheres with given luminosities. and the Fermi-Dirac distribution of given temperatures. We find that the stalled shock revives due to the neutrino heating aided by SASI for cases with L νe ≥3.9x10 52 ergss -1 and the as-pherical shock passes through the outer layers of the star (≥10,000 km), with the explosion energies of ∼10 51 ergs.Next we examine abundances and masses of the supernova ejecta. We find that masses of the ejecta and 56 Ni correlate with the neutrino luminosity, and 56 Ni mass is comparable to that observed in SN 1987A. We also find that abundance pattern of the supernova ejecta is similar to that of the solar system, for cases with high explosion energies of >10 51 ergs. We emphasize that 64 Zn, which is underproduced in the spherical case, is abundantly produced in slightly neutron-rich ejecta.

  7. Magnetohydrodynamic Convection in the Outer Core and its Geodynamic Consequences

    Science.gov (United States)

    Kuang, Weijia; Chao, Benjamin F.; Fang, Ming

    2004-01-01

    The Earth's fluid outer core is in vigorous convection through much of the Earth's history. In addition to generating and maintaining Earth s time-varying magnetic field (geodynamo), the core convection also generates mass redistribution in the core and a dynamical pressure field on the core-mantle boundary (CMB). All these shall result in various core-mantle interactions, and contribute to surface geodynamic observables. For example, electromagnetic core-mantle coupling arises from finite electrically conducting lower mantle; gravitational interaction occurs between the cores and the heterogeneous mantle; mechanical coupling may also occur when the CMB topography is aspherical. Besides changing the mantle rotation via the coupling torques, the mass-redistribution in the core shall produce a spatial-temporal gravity anomaly. Numerical modeling of the core dynamical processes contributes in several geophysical disciplines. It helps explain the physical causes of surface geodynamic observables via space geodetic techniques and other means, e.g. Earth's rotation variation on decadal time scales, and secular time-variable gravity. Conversely, identification of the sources of the observables can provide additional insights on the dynamics of the fluid core, leading to better constraints on the physics in the numerical modeling. In the past few years, our core dynamics modeling efforts, with respect to our MoSST model, have made significant progress in understanding individual geophysical consequences. However, integrated studies are desirable, not only because of more mature numerical core dynamics models, but also because of inter-correlation among the geophysical phenomena, e.g. mass redistribution in the outer core produces not only time-variable gravity, but also gravitational core-mantle coupling and thus the Earth's rotation variation. They are expected to further facilitate multidisciplinary studies of core dynamics and interactions of the core with other

  8. On the solution self-assembly of nanocolloidal brushes: insights from simulations

    International Nuclear Information System (INIS)

    Striolo, Alberto

    2008-01-01

    The synthesis of novel nanoparticles with exceptional properties continues to stimulate the search for advanced applications in fields as diverse as solar energy harvesting and polymer reinforcement. It is widely recognized that to practically exploit the promised benefits it is necessary to guide the assembly of the various nanoparticles into well-defined supra-molecular structures. Towards this goal, we report Monte Carlo simulation results for the self-assembly of spherical nanoparticles in implicit solvent. The nanoparticles interact solely via dispersive interactions, modeled as square-well potentials. To control the morphology of the self-assembled aggregates, side chains are grafted on specific locations on the nanoparticle surface (i.e., on the equator, on the tropics, on the entire tropical region, or uniformly on the nanoparticle surface). The results are discussed in terms of average cluster size, probability of observing aggregates of given size, and aggregate radius of gyration and asphericity as a function of the aggregate size. The parameters of interest are the solution conditions and the nanoparticle volume fraction (always in the dilute regime). As shown in previous reports (e.g., Striolo 2007 Small 3 628), the nanoparticles form insoluble agglomerates in the absence of the side chains. When the side chains are long and uniformly distributed on the nanoparticles, these remain individually dispersed in solution. More importantly, when the side chains are grafted on selected locations on the nanoparticles, these self-assemble, yielding structures composed of up to 7-10 nanoparticles. The number of grafted side chains is the parameter that predominantly determines the average aggregate size, while the aggregate morphology can be tuned by appropriately controlling the distribution and length of the grafted side chains.

  9. Coarse-graining to the meso and continuum scales with molecular-dynamics-like models

    Science.gov (United States)

    Plimpton, Steve

    Many engineering-scale problems that industry or the national labs try to address with particle-based simulations occur at length and time scales well beyond the most optimistic hopes of traditional coarse-graining methods for molecular dynamics (MD), which typically start at the atomic scale and build upward. However classical MD can be viewed as an engine for simulating particles at literally any length or time scale, depending on the models used for individual particles and their interactions. To illustrate I'll highlight several coarse-grained (CG) materials models, some of which are likely familiar to molecular-scale modelers, but others probably not. These include models for water droplet freezing on surfaces, dissipative particle dynamics (DPD) models of explosives where particles have internal state, CG models of nano or colloidal particles in solution, models for aspherical particles, Peridynamics models for fracture, and models of granular materials at the scale of industrial processing. All of these can be implemented as MD-style models for either soft or hard materials; in fact they are all part of our LAMMPS MD package, added either by our group or contributed by collaborators. Unlike most all-atom MD simulations, CG simulations at these scales often involve highly non-uniform particle densities. So I'll also discuss a load-balancing method we've implemented for these kinds of models, which can improve parallel efficiencies. From the physics point-of-view, these models may be viewed as non-traditional or ad hoc. But because they are MD-style simulations, there's an opportunity for physicists to add statistical mechanics rigor to individual models. Or, in keeping with a theme of this session, to devise methods that more accurately bridge models from one scale to the next.

  10. Cataract and progressing keratoconus — solution?

    Directory of Open Access Journals (Sweden)

    K. B. Pershin

    2015-01-01

    Full Text Available Purpose: To develop an uniform method of the treatment for patients with progressive keratoconus (stage 1‑2 and cataract. Patients and methods: 4 patients (5 eyes with cataract and progressive keratoconus stage 1‑2 were enrolled in the study. Mean age was 42 years. In all patients, standard ophthalmic examination as well corneal topography, anterior segment optical coherence tomography, biometry, and IOL power calculations using IOLMaster were performed. Mean uncorrected visual acuity (UCVA was 0.1 while mean best-corrected visual acuity (BCVA was 0.4. Surgical technique included two steps. The first step was the creation of corneal tunnels with femtosecond laser with subsequent phaco and monofocal aspheric IOL implantation. The second step (1‑2 weeks later was the implantation of intrastromal ring segments based on corneal topography and corneal crosslinking.Results: After the first step, all patients had myopic refraction (from –1.0 D to –2.5 D. Cylindrical component was almost unchanged. After the second step, the patients reported the vision improvement, mainly due to UCVA. Both spherical (myopic and cylindrical components decreased, mainly due to the steep meridian. After the treatment, optical power of the cornea decreased, mainly due to the steep meridian. UCVA was 0.6 or more in 60 % of cases, final BCVA was 0.8‑1.0 in 80 % of cases. Neither intraoperative nor postoperative (follow-up was 2 years complications were observed.Conclusions: Combined phaco and prior creation of corneal tunnels with subsequent intrastromal ring segment implantation and crosslinking in patients with cataract and progressive keratoconus stage 1‑2 is safe, provides good predictable outcome and significantly reduces rehabilitation period.

  11. Topographic characteristics of keratoconus among a sample of Jordanian patients

    Directory of Open Access Journals (Sweden)

    Mohammed Ali Abu Ameerh

    2014-08-01

    Full Text Available AIM:To identify topographic characteristics of keratoconus in a Jordanian sample.METHODS:This study characterized 210 corneas affected with keratoconus presenting to Jordan University Hospital. Patients were diagnosed based on clinical examinations and Pentacam imaging. Eyes of males (n=101 were of a similar proportion to females (n=109. All of the 111 patients were affected bilaterally. Ages ranged between 13 and 44y with a mean age of 25.2y.RESULTS:Results revealed significant differences between males and females at the level of the flat curvature power, basement membrane thickness and size of the anterior chamber. Eyes were arranged in three groups based on severity levels:mild, moderate and severe determined by the mean curvature power (Km. Results show that the flat (K1 and steep (K2 curvature powers, corneal asphericity coefficient (QV, thinnest point, pachy apex and basement membrane thickness are significantly different among the three groups, but not the corneal and anterior chamber volumes. Morphological analyses, based on sagittal maps, show no differences in keratometric values between eyes with different sagittal patterns except for the vertical location of the pachy apex relative to the pupil center and the thinnest point. Eyes with the island front elevation map are significantly more affected than eyes with the U shape and the ridge pattern.CONCLUSION:All keratometric values measured except for corneal and anterior chamber volumes vary significantly with disease severity. The vertical pachy apex location correlates well with severity levels while the horizontal location seems to have no effect. Our study also indicates that front elevation maps may be a better predictor of the severity of keratoconus than sagittal maps.

  12. Highlights from 4STAR Sky-Scanning Retrievals of Aerosol Intensive Optical Properties from Multiple Field Campaigns with Detailed Comparisons of SSA Reported During SEAC4RS

    Science.gov (United States)

    Dunagan, Stephen E.

    2016-01-01

    The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument combines airborne sun tracking capabilities of the Ames Airborne Tracking Sun Photometer (AATS-14) with AERONET (Aerosol Robotic Network)-like sky-scanning capability and adds state-of-the-art fiber-coupled grating spectrometry to yield hyperspectral measurements of direct solar irradiance and angularly resolved sky radiance. The combination of sun-tracking and sky-scanning capability enables retrievals of wavelength-dependent aerosol optical depth (AOD), mode-resolved aerosol size distribution (SD), asphericity, and complex refractive index, and thus also the scattering phase function, asymmetry parameter, single-scattering albedo (SSA), and absorption aerosol optical thickness (AAOT). From 2012 to 2014 4STAR participated in four major field campaigns: the U.S. Dept. of Energy's TCAP (Two-Column Aerosol Project) I & II campaigns, and NASA's SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) and ARISE (Arctic Radiation - IceBridge Sea & Ice Experiment) campaigns. Establishing a strong performance record, 4STAR operated successfully on all flights conducted during each of these campaigns. Sky radiance spectra from scans in either constant azimuth (principal plane) or constant zenith angle (almucantar) were interspersed with direct beam measurements during level legs. During SEAC4RS and ARISE, 4STAR airborne measurements were augmented with flight-level albedo from the collocated Shortwave Spectral Flux Radiometer (SSFR) providing improved specification of below-aircraft radiative conditions for the retrieval. Calibrated radiances and retrieved products will be presented with particular emphasis on detailed comparisons of ambient SSA retrievals and measurements during SEAC4RS from 4STAR, AERONET, HSRL2 (High Spectral Resolution Lidar), and from in situ measurements.

  13. 4STAR Sky-Scanning Retrievals of Aerosol Intensive Optical Properties from Multiple Field Campaigns with Detailed Comparisons of SSA Reported During SEAC4RS

    Science.gov (United States)

    Flynn, Connor; Dahlgren, R. P.; Dunagan, S.; Johnson, R.; Kacenelenbogen, M.; LeBlanc, S.; Livingston, J.; Redemann, J.; Schmid, B.; Segal Rozenhaimer, M.; hide

    2015-01-01

    The 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument combines airborne sun tracking capabilities of the Ames Airborne Tracking Sun Photometer (AATS-14) with AERONET-like sky-scanning capability and adds state-of-the-art fiber-coupled grating spectrometry to yield hyper spectral measurements of direct solar irradiance and angularly resolved sky radiance. The combination of sun-tracking and sky-scanning capability enables retrievals of wavelength-dependent aerosol optical depth (AOD), mode-resolved aerosol size distribution (SD), asphericity, and complex refractive index, and thus also the scattering phase function, asymmetry parameter, single-scattering albedo (SSA), and absorption aerosol optical thickness (AAOT).From 2012 to 2014 4STAR participated in four major field campaigns: the U.S. Dept. of Energy TCAP I II campaigns, and NASAs SEAC4RS and ARISE campaigns. Establishing a strong performance record, 4STAR operated successfully on all flights conducted during each of these campaigns. Sky radiance spectra from scans in either constant azimuth (principal plane) or constant zenith angle (almucantar) were interspersed with direct beam measurements during level legs. During SEAC4RS and ARISE, 4STAR airborne measurements were augmented with flight-level albedo from the collocated Shortwave Spectral Flux Radiometer (SSFR) providing improved specification of below-aircraft radiative conditions for the retrieval. Calibrated radiances and retrieved products will be presented with particular emphasis on detailed comparisons of ambient SSA retrievals and measurements during SEAC4RS from 4STAR, AERONET, HSRL2, and from in situ measurements.

  14. Student project of optical system analysis API-library development

    Science.gov (United States)

    Ivanova, Tatiana; Zhukova, Tatiana; Dantcaranov, Ruslan; Romanova, Maria; Zhadin, Alexander; Ivanov, Vyacheslav; Kalinkina, Olga

    2017-08-01

    In the paper API-library software developed by students of Applied and Computer Optics Department (ITMO University) for optical system design is presented. The library performs paraxial and real ray tracing, calculates 3d order (Seidel) aberration and real ray aberration of axis and non-axis beams (wave, lateral, longitudinal, coma, distortion etc.) and finally, approximate wave aberration by Zernike polynomials. Real aperture can be calculated by considering of real rays tracing failure on each surface. So far we assume optical system is centered, with spherical or 2d order aspherical surfaces. Optical glasses can be set directly by refraction index or by dispersion coefficients. The library can be used for education or research purposes in optical system design area. It provides ready to use software functions for optical system simulation and analysis that developer can simply plug into their software development for different purposes, for example for some specific synthesis tasks or investigation of new optimization modes. In the paper we present an example of using the library for development of cemented doublet synthesis software based on Slusarev's methodology. The library is used in optical system optimization recipes course for deep studying of optimization model and its application for optical system design. Development of such software is an excellent experience for students and help to understanding optical image modeling and quality analysis. This development is organized as student group joint project. We try to organize it as a group in real research and development project, so each student has his own role in the project and then use whole library functionality in his own master or bachelor thesis. Working in such group gives students useful experience and opportunity to work as research and development engineer of scientific software in the future.

  15. GRAVITATIONAL WAVE SIGNATURES OF HYPERACCRETING COLLAPSAR DISKS

    International Nuclear Information System (INIS)

    Kotake, Kei; Takiwaki, Tomoya; Harikae, Seiji

    2012-01-01

    By performing two-dimensional special relativistic (SR) magnetohydrodynamic simulations, we study possible signatures of gravitational waves (GWs) in the context of the collapsar model for long-duration gamma-ray bursts. In our SR simulations, the central black hole is treated as an absorbing boundary. By doing so, we focus on the GWs generated by asphericities in neutrino emission and matter motions in the vicinity of the hyperaccreting disks. We compute nine models by adding initial angular momenta and magnetic fields parametrically to a precollapse core of a 35 M ☉ progenitor star. As for the microphysics, a realistic equation of state is employed and the neutrino cooling is taken into account via a multi-flavor neutrino leakage scheme. To accurately estimate GWs produced by anisotropic neutrino emission, we perform a ray-tracing analysis in general relativity by a post-processing procedure. By employing a stress formula that includes contributions from both magnetic fields and SR corrections, we also study the effects of magnetic fields on the gravitational waveforms. We find that the GW amplitudes from anisotropic neutrino emission show a monotonic increase with time, whose amplitudes are much larger than those from matter motions of the accreting material. We show that the increasing trend of the neutrino GWs stems from the excess of neutrino emission in the direction near parallel to the spin axis illuminated from the hyperaccreting disks. We point out that a recently proposed future space-based interferometer like Fabry-Perot-type DECIGO would permit the detection of these GW signals within ≈100 Mpc.

  16. Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

    Science.gov (United States)

    Tomita, Minoru; Watabe, Miyuki; Yukawa, Satoshi; Nakamura, Nobuo; Nakamura, Tadayuki; Magnago, Thomas

    2014-02-01

    To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. Private LASIK center, Tokyo, Japan. Case series. Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (PLaser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. Optical observations of the type Ic supernova 2007gr in NGC 1058

    International Nuclear Information System (INIS)

    Chen, Juncheng; Wang, Xiaofeng; Li, Junzheng; Ganeshalingam, Mohan; Silverman, Jeffrey M.; Filippenko, Alexei V.; Li, Weidong; Chornock, Ryan; Steele, Thea

    2014-01-01

    We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t = –8 days) shows a possible signature of helium (He I λ5876 at a velocity of ∼19,000 km s –1 ). Moreover, the larger intensity ratio of the [O I] λ6300 and λ6364 lines inferred from the early nebular spectra implies a lower opacity of the ejecta shortly after the explosion. These results indicate that SN 2007gr perhaps underwent a less energetic explosion of a smaller-mass Wolf-Rayet star (∼8-9 M ☉ ) in a binary system, as favored by an analysis of the progenitor environment through pre-explosion and post-explosion Hubble Space Telescope images. In the nebular spectra, asymmetric double-peaked profiles can be seen in the [O I] λ6300 and Mg I] λ4571 lines. We suggest that the two peaks are contributed by the blueshifted and rest-frame components. The similarity in velocity structure and the different evolution of the strength of the two components favor an aspherical explosion with the ejecta distributed in a torus or disk-like geometry, but inside the ejecta the O and Mg have different distributions.

  18. SIMULATIONS OF RECOILING MASSIVE BLACK HOLES IN THE VIA LACTEA HALO

    International Nuclear Information System (INIS)

    Guedes, J.; Madau, P.; Diemand, J.; Kuhlen, M.; Zemp, M.

    2009-01-01

    The coalescence of a massive black hole (MBH) binary leads to the gravitational-wave recoil of the system and its ejection from the galaxy core. We have carried out N-body simulations of the motion of a M BH = 3.7 x 10 6 M sun MBH remnant in the 'Via Lactea I' simulation, a Milky Way-sized dark matter halo. The black hole receives a recoil velocity of V kick = 80, 120, 200, 300, and 400 km s -1 at redshift 1.5, and its orbit is followed for over 1 Gyr within a 'live' host halo, subject only to gravity and dynamical friction against the dark matter background. We show that, owing to asphericities in the dark matter potential, the orbit of the MBH is highly nonradial, resulting in a significantly increased decay timescale compared to a spherical halo. The simulations are used to construct a semi-analytic model of the motion of the MBH in a time-varying triaxial Navarro-Frenk-White dark matter halo plus a spherical stellar bulge, where the dynamical friction force is calculated directly from the velocity dispersion tensor. Such a model should offer a realistic picture of the dynamics of kicked MBHs in situations where gas drag, friction by disk stars, and the flattening of the central cusp by the returning black hole are all negligible effects. We find that MBHs ejected with initial recoil velocities V kick ∼> 500 km s -1 do not return to the host center within a Hubble time. In a Milky Way-sized galaxy, a recoiling hole carrying a gaseous disk of initial mass ∼M BH may shine as a quasar for a substantial fraction of its 'wandering' phase. The long decay timescales of kicked MBHs predicted by this study may thus be favorable to the detection of off-nuclear quasar activity.

  19. Intraocular lens alignment from purkinje and Scheimpflug imaging.

    Science.gov (United States)

    Rosales, Patricia; De Castro, Alberto; Jiménez-Alfaro, Ignacio; Marcos, Susana

    2010-11-01

    The improved designs of intraocular lenses (IOLs) implanted during cataract surgery demand understanding of the possible effects of lens misalignment on optical performance. In this review, we describe the implementation, set-up and validation of two methods to measure in vivo tilt and decentration of IOLs, one based on Purkinje imaging and the other on Scheimpflug imaging. The Purkinje system images the reflections of an oblique collimated light source on the anterior cornea and anterior and posterior IOL surfaces and relies on the well supported assumption of the linearity of the Purkinje images with respect to IOL tilt and decentration. Scheimpflug imaging requires geometrical distortion correction and image processing techniques to retrieve the pupillary axis, IOL axis and pupil centre from the three-dimensional anterior segment image of the eye. Validation of the techniques using a physical eye model indicates that IOL tilt is estimated within an accuracy of 0.261 degree and decentration within 0.161 mm. Measurements on patients implanted with aspheric IOLs indicate that IOL tilt and decentration tend to be mirror symmetric between left and right eyes. The average tilt was 1.54 degrees and the average decentration was 0.21 mm. Simulated aberration patterns using custom models of the patients eyes, built using anatomical data of the anterior cornea and foveal position, the IOL geometry and the measured IOL tilt and decentration predict the experimental wave aberrations measured using laser ray tracing aberrometry on the same eyes. This reveals a relatively minor contribution of IOL tilt and decentration on the higher-order aberrations of the normal pseudophakic eye.

  20. Influence on Visual Quality of Intraoperative Orientation of Asymmetric Intraocular Lenses.

    Science.gov (United States)

    Bonaque-González, Sergio; Ríos, Susana; Amigó, Alfredo; López-Gil, Norberto

    2015-10-01

    To evaluate visual quality when changing the intraocular orientation of the Lentis Mplus LS-312MF nonrotational symmetric +3.00 diopters aspheric multifocal intraocular lens ([IOL] Oculentis GmbH, Berlin, Germany) in normal eyes. An artificial eye was used to measure the in vitro wavefront of the IOL. The corneal topography of 20 healthy patients was obtained. For each eye, a computational analysis simulated the implantation of the IOL. The modulation transfer function (MTF) and an image quality parameter (visually modulated transfer function [VSMTF] metric) were calculated for a 5.0-mm pupil and for three conditions: distance, intermediate, and near vision. The procedure was repeated for each eye after a rotation of the IOL with respect to the cornea from 0° to 360° in 1° steps. Statistical analysis showed significant differences in mean VSMTF values between orientations for distance vision. Optimal orientation of the IOL (different for each eye) showed a mean improvement of 58% ± 19% (range: 20% to 121%) in VSMTF values with respect to the worst possible orientation. For these orientations, intermediate and near vision quality were statistically indistinguishable. The MTFs were different between orientations, showing a mean difference of approximately 5 cycles per degree in the maximum spatial frequencies that can be transferred between the best and the worst orientations for distance vision. The results suggest that implantation of this nonrotational symmetric IOL should improve visual outcomes if it is oriented to coincide with a customized meridian. A simple, practical method is proposed to find an approximation to the angle that an Mplus IOL should be inserted. Copyright 2015, SLACK Incorporated.

  1. Piggyback intraocular lens implantation to correct pseudophakic refractive error after segmental multifocal intraocular lens implantation.

    Science.gov (United States)

    Venter, Jan A; Oberholster, Andre; Schallhorn, Steven C; Pelouskova, Martina

    2014-04-01

    To evaluate refractive and visual outcomes of secondary piggyback intraocular lens implantation in patients diagnosed as having residual ametropia following segmental multifocal lens implantation. Data of 80 pseudophakic eyes with ametropia that underwent Sulcoflex aspheric 653L intraocular lens implantation (Rayner Intraocular Lenses Ltd., East Sussex, United Kingdom) to correct residual refractive error were analyzed. All eyes previously had in-the-bag zonal refractive multifocal intraocular lens implantation (Lentis Mplus MF30, models LS-312 and LS-313; Oculentis GmbH, Berlin, Germany) and required residual refractive error correction. Outcome measurements included uncorrected distance visual acuity, corrected distance visual acuity, uncorrected near visual acuity, distance-corrected near visual acuity, manifest refraction, and complications. One-year data are presented in this study. The mean spherical equivalent ranged from -1.75 to +3.25 diopters (D) preoperatively (mean: +0.58 ± 1.15 D) and reduced to -1.25 to +0.50 D (mean: -0.14 ± 0.28 D; P < .01). Postoperatively, 93.8% of eyes were within ±0.50 D and 98.8% were within ±1.00 D of emmetropia. The mean uncorrected distance visual acuity improved significantly from 0.28 ± 0.16 to 0.01 ± 0.10 logMAR and 78.8% of eyes achieved 6/6 (Snellen 20/20) or better postoperatively. The mean uncorrected near visual acuity changed from 0.43 ± 0.28 to 0.19 ± 0.15 logMAR. There was no significant change in corrected distance visual acuity or distance-corrected near visual acuity. No serious intraoperative or postoperative complications requiring secondary intraocular lens removal occurred. Sulcoflex lenses proved to be a predictable and safe option for correcting residual refractive error in patients diagnosed as having pseudophakia. Copyright 2014, SLACK Incorporated.

  2. A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

    International Nuclear Information System (INIS)

    Stockett, Mark H.; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen

    2016-01-01

    A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

  3. A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stockett, Mark H., E-mail: stockett@phys.au.dk; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark)

    2016-05-15

    A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

  4. Design of a portable optical emission tomography system for microwave induced compact plasma for visible to near-infrared emission lines

    Energy Technology Data Exchange (ETDEWEB)

    Rathore, Kavita, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in; Munshi, Prabhat, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in [Nuclear Engineering and Technology Programme, Indian Institute of Technology Kanpur, Kanpur (India); Bhattacharjee, Sudeep, E-mail: kavira@iitk.ac.in, E-mail: pmunshi@iitk.ac.in, E-mail: sudeepb@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2016-03-15

    A new non-invasive diagnostic system is developed for Microwave Induced Plasma (MIP) to reconstruct tomographic images of a 2D emission profile. A compact MIP system has wide application in industry as well as research application such as thrusters for space propulsion, high current ion beams, and creation of negative ions for heating of fusion plasma. Emission profile depends on two crucial parameters, namely, the electron temperature and density (over the entire spatial extent) of the plasma system. Emission tomography provides basic understanding of plasmas and it is very useful to monitor internal structure of plasma phenomena without disturbing its actual processes. This paper presents development of a compact, modular, and versatile Optical Emission Tomography (OET) tool for a cylindrical, magnetically confined MIP system. It has eight slit-hole cameras and each consisting of a complementary metal–oxide–semiconductor linear image sensor for light detection. The optical noise is reduced by using aspheric lens and interference band-pass filters in each camera. The entire cylindrical plasma can be scanned with automated sliding ring mechanism arranged in fan-beam data collection geometry. The design of the camera includes a unique possibility to incorporate different filters to get the particular wavelength light from the plasma. This OET system includes selected band-pass filters for particular argon emission 750 nm, 772 nm, and 811 nm lines and hydrogen emission H{sub α} (656 nm) and H{sub β} (486 nm) lines. Convolution back projection algorithm is used to obtain the tomographic images of plasma emission line. The paper mainly focuses on (a) design of OET system in detail and (b) study of emission profile for 750 nm argon emission lines to validate the system design.

  5. Clinical Outcomes after Uncomplicated Cataract Surgery with Implantation of the Tecnis Toric Intraocular Lens

    Directory of Open Access Journals (Sweden)

    Wojciech Lubiński

    2016-01-01

    Full Text Available Purpose. To evaluate the clinical outcomes after uncomplicated cataract surgery with implantation of an aspheric toric intraocular lens (IOL during a 6-month follow-up. Methods. Prospective study including 27 consecutive eyes of 18 patients (mean age: 66.1±11.4 years with a visually significant cataract and corneal astigmatism ≥ 0.75 D and undergoing uncomplicated cataract surgery with implantation of the Tecnis ZCT toric IOL (Abbott Medical Optics. Visual, refractive, and keratometric outcomes as well as IOL rotation were evaluated during a 6-month follow-up. At the end of the follow-up, patient satisfaction and perception of optical/visual disturbances were also evaluated using a subjective questionnaire. Results. At 6 months after surgery, mean LogMAR uncorrected (UDVA and corrected distance visual acuity (CDVA were 0.19±0.12 and 0.14±0.10, respectively. Postoperative UDVA of 20/40 or better was achieved in 92.6% of eyes. Mean refractive cylinder decreased significantly from −3.73±1.96 to −1.42±0.88 D (p<0.001, while keratometric cylinder did not change significantly (p=0.44. Mean absolute IOL rotation was 1.1±2.4°, with values of more than 5° in only 2 eyes (6.9%. Mean patient satisfaction score was 9.70±0.46, using a scale from 0 (not at all satisfied to 10 (very satisfied. No postoperative optical/visual disturbances were reported. Conclusion. Cataract surgery with implantation of the Tecnis toric IOL is an effective method of refractive correction in eyes with corneal astigmatism due to the good IOL positional stability, providing high levels of patient’s satisfaction.

  6. Letter to the Editor: A strange cloud in the Arctic summer stratosphere 1998 above Esrange (68°N, Sweden

    Directory of Open Access Journals (Sweden)

    J. Siebert

    2000-04-01

    Full Text Available When the University of Bonn lidar on the Esrange (68°N, 21°E, Sweden, was switched on in the evening of July 18, 1998, a geometrically and optically thin cloud layer was present near 14 km altitude or 400 K potential temperature, where it persisted for two hours. The tropopause altitude was 4 km below the cloud altitude. The cloud particles depolarized the lidar returns, thus must they have been aspherical and hence solid. Atmospheric temperatures near 230 K were approximately 40 K too high to support ice particles at stratospheric water vapour pressures of a few ppmv. The isentropic back trajectory on 400 K showed the air parcels to have stayed clear of active major rocket launch sites. The air parcels at 400 K had traveled from the Aleutians across Canada and the Atlantic Ocean arriving above central Europe and then turned northward to pass over above the lidar station. Parcels at levels at ±25 K from 400 K had come from the pole and joined the 400 K trajectory path above eastern Canada. Apparently the cloud existed in a filament of air with an origin different from those filaments both above and below. Possibly the 400 K level air parcels had carried soot particles from forest wild fires in northern Canada or volcanic ash from the eruption of the Korovin Volcano in the Aleutian Islands.Key words: Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions · Meteorology and atmospheric dynamics (middle atmospheric dynamics

  7. Letter to the Editor: A strange cloud in the Arctic summer stratosphere 1998 above Esrange (68°N, Sweden

    Directory of Open Access Journals (Sweden)

    K. H. Fricke

    Full Text Available When the University of Bonn lidar on the Esrange (68°N, 21°E, Sweden, was switched on in the evening of July 18, 1998, a geometrically and optically thin cloud layer was present near 14 km altitude or 400 K potential temperature, where it persisted for two hours. The tropopause altitude was 4 km below the cloud altitude. The cloud particles depolarized the lidar returns, thus must they have been aspherical and hence solid. Atmospheric temperatures near 230 K were approximately 40 K too high to support ice particles at stratospheric water vapour pressures of a few ppmv. The isentropic back trajectory on 400 K showed the air parcels to have stayed clear of active major rocket launch sites. The air parcels at 400 K had traveled from the Aleutians across Canada and the Atlantic Ocean arriving above central Europe and then turned northward to pass over above the lidar station. Parcels at levels at ±25 K from 400 K had come from the pole and joined the 400 K trajectory path above eastern Canada. Apparently the cloud existed in a filament of air with an origin different from those filaments both above and below. Possibly the 400 K level air parcels had carried soot particles from forest wild fires in northern Canada or volcanic ash from the eruption of the Korovin Volcano in the Aleutian Islands.Key words: Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions · Meteorology and atmospheric dynamics (middle atmospheric dynamics

  8. New trends in intraocular lens imaging

    Science.gov (United States)

    Millán, María S.; Alba-Bueno, Francisco; Vega, Fidel

    2011-08-01

    As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a customized procedure to compensate for important sources of image degradation in the visual system of a patient, such as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand, testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea. Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena, such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle, accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the

  9. Advanced integrated WDM system for POF communication

    Science.gov (United States)

    Haupt, M.; Fischer, U. H. P.

    2009-01-01

    Polymer Optical Fibres (POFs) show clear advantages compared to copper and glass fibres. In essence, POFs are inexpensive, space-saving and not susceptible to electromagnetic interference. Thus, the usage of POFs have become a reasonable alternative in short distance data communication. Today, POFs are applied in a wide number of applications due to these specific advantages. These applications include automotive communication systems and in-house-networks. State-of-the-art is to transmit data with only one channel over POF, this limits the bandwidth. To solve this problem, an integrated MUX/DEMUX-element for WDM over POF is designed and developed to use multiple channels. This integration leads to low costs, therefore this component is suitable for mass market applications. The fundamental idea is to separate the chromatic parts of the light in its monochromatic components by means of a grating based on an aspheric mirror. Due to the high NA of the POF the setup has to be designed in a 3D-approach. Therefore this setup cannot be compared with the planar solutions available on market, they would result high losses in the 3rd dimension. To achieve a fast and optimized design an optical simulation program is used. Particular attention has to be paid to the design of the POF as a light source in the simulation program and the optimisation of the grating. The following realization of the demultiplexer is planed to be done with injection molding. This technology offers easy and very economical processing. These advantages make this technology first choice for optical components in the low-cost array.

  10. Electron density distribution in ferromagnetic nickel: A γ -ray diffraction study

    Science.gov (United States)

    Jauch, W.; Reehuis, M.

    2008-12-01

    High-accuracy single-crystal structure factors, complete up to sinθ/λ=1.9Å-1 , have been measured from ferromagnetic nickel at 295 K using 316.5-keV gamma radiation. The experimental uncertainty of the structure factors is of the order of 10 millielectrons per atom for all data. A detailed description of the electron density distribution is presented in terms of a multipolar atomic deformation model. Achievement of a reliable Debye-Waller factor is of vital importance in this context. The charge asphericity is due to an excess eg orbital occupancy of 43.4(2)%. The 3d shell in the metal is contracted by 2.07(5)% relative to the free atom. The results are discussed and compared with earlier experimental and theoretical works. In contrast to bcc Cr and Fe, solid-state effects are less pronounced in fcc Ni. Clear disentanglement between the 3d and 4s valence electrons could be accomplished for the first time. The general expectation that the number of 3d electrons in the metal should be increased as compared to the atom was confirmed in the case of iron by combining spin and charge-density data. In the case of nickel, it is rejected as revealed by the γ -ray data alone. Only with the d8 configuration, consistency is achieved between observed and refined mosaic widths of the sample crystal. A 3d8 configuration implies that the majority-spin d band cannot be full. Strong support is lent to a localized atomic character of the valence electrons.

  11. THE LAST MINUTES OF OXYGEN SHELL BURNING IN A MASSIVE STAR

    Energy Technology Data Exchange (ETDEWEB)

    Müller, Bernhard [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom); Viallet, Maxime; Janka, Hans-Thomas [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Heger, Alexander, E-mail: b.mueller@qub.ac.uk [Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Victoria 3800 (Australia)

    2016-12-10

    We present the first  4 π– three-dimensional (3D) simulation of the last minutes of oxygen shell burning in an 18 M {sub ⊙} supernova progenitor up to the onset of core collapse. A moving inner boundary is used to accurately model the contraction of the silicon and iron core according to a one-dimensional stellar evolution model with a self-consistent treatment of core deleptonization and nuclear quasi-equilibrium. The simulation covers the full solid angle to allow the emergence of large-scale convective modes. Due to core contraction and the concomitant acceleration of nuclear burning, the convective Mach number increases to ∼0.1 at collapse, and an ℓ  = 2 mode emerges shortly before the end of the simulation. Aside from a growth of the oxygen shell from 0.51 M {sub ⊙} to 0.56 M {sub ⊙} due to entrainment from the carbon shell, the convective flow is reasonably well described by mixing-length theory, and the dominant scales are compatible with estimates from linear stability analysis. We deduce that artificial changes in the physics, such as accelerated core contraction, can have precarious consequences for the state of convection at collapse. We argue that scaling laws for the convective velocities and eddy sizes furnish good estimates for the state of shell convection at collapse and develop a simple analytic theory for the impact of convective seed perturbations on shock revival in the ensuing supernova. We predict a reduction of the critical luminosity for explosion by 12% – 24% due to seed asphericities for our 3D progenitor model relative to the case without large seed perturbations.

  12. Advances in the production of freeform optical surfaces

    Science.gov (United States)

    Tohme, Yazid E.; Luniya, Suneet S.

    2007-05-01

    Recent market demands for free-form optics have challenged the industry to find new methods and techniques to manufacture free-form optical surfaces with a high level of accuracy and reliability. Production techniques are becoming a mix of multi-axis single point diamond machining centers or deterministic ultra precision grinding centers coupled with capable measurement systems to accomplish the task. It has been determined that a complex software tool is required to seamlessly integrate all aspects of the manufacturing process chain. Advances in computational power and improved performance of computer controlled precision machinery have driven the use of such software programs to measure, visualize, analyze, produce and re-validate the 3D free-form design thus making the process of manufacturing such complex surfaces a viable task. Consolidation of the entire production cycle in a comprehensive software tool that can interact with all systems in design, production and measurement phase will enable manufacturers to solve these complex challenges providing improved product quality, simplified processes, and enhanced performance. The work being presented describes the latest advancements in developing such software package for the entire fabrication process chain for aspheric and free-form shapes. It applies a rational B-spline based kernel to transform an optical design in the form of parametrical definition (optical equation), standard CAD format, or a cloud of points to a central format that drives the simulation. This software tool creates a closed loop for the fabrication process chain. It integrates surface analysis and compensation, tool path generation, and measurement analysis in one package.

  13. Jeans that fit: weighing the mass of the Milky Way analogues in the ΛCDM universe

    Science.gov (United States)

    Kafle, Prajwal R.; Sharma, Sanjib; Robotham, Aaron S. G.; Elahi, Pascal J.; Driver, Simon P.

    2018-04-01

    The spherical Jeans equation is a widely used tool for dynamical study of gravitating systems in astronomy. Here, we test its efficacy in robustly weighing the mass of Milky Way analogues, given they need not be in equilibrium or even spherical. Utilizing Milky Way stellar haloes simulated in accordance with Λ cold dark matter (ΛCDM) cosmology by Bullock and Johnston and analysing them under the Jeans formalism, we recover the underlying mass distribution of the parent galaxy, within distance r/kpc ∈ [10, 100], with a bias of ˜ 12 per cent and a dispersion of ˜ 14 per cent. Additionally, the mass profiles of triaxial dark matter haloes taken from the SURFS simulation, within scaled radius 0.2 < r/rmax < 3, are measured with a bias of ˜ - 2.4 per cent and a dispersion of ˜ 10 per cent. The obtained dispersion is not because of Poisson noise due to small particle numbers as it is twice the later. We interpret the dispersion to be due to the inherent nature of the ΛCDM haloes, for example being aspherical and out-of-equilibrium. Hence, the dispersion obtained for stellar haloes sets a limit of about 12 per cent (after adjusting for random uncertainty) on the accuracy with which the mass profiles of the Milky Way-like galaxies can be reconstructed using the spherical Jeans equation. This limit is independent of the quantity and quality of the observational data. The reason for a non-zero bias is not clear, hence its interpretation is not obvious at this stage.

  14. Observation of meander pattern in signals from superconducting MgB{sub 2} detector by scanning pulsed laser imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Takekazu, E-mail: ishida@center.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yagi, Ikutaro; Yoshioka, Naohito; Huy, Ho Thanh [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yotsuya, Tsutomu [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, 2-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Shimakage, Hisashi [Department of Electrical and Electronic Engineering, College of Engineering, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Miki, Shigehito [Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan); Wang, Zhen [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan)

    2013-01-15

    Highlights: ► We fabricate a superconducting MgB{sub 2} meander detector as a solid-state neutron detector. ► MgB{sub 2} detector uses XYZ stage, optical fiber and focused lens to scan as a microscope. ► The 6 μm line-and-space in meandering pattern can be resolved in signals against pulsed laser. -- Abstract: Superconducting MgB{sub 2} meander detector has been imaged by scanning a spot of 1.5-μm focused pulsed laser. The superconducting detector using high-quality {sup 10}B-enriched MgB{sub 2} thin films at higher operating temperatures has been fabricated to utilize a resistance change induced by the nuclear energy of {sup 10}B and neutron. The MgB{sub 2} detector consists of a 200-nm-thick MgB{sub 2} thin-film meander line, a 300-nm-thick SiO protective layer, and 150-nm-thick Nb electrodes with 1-μm MgB{sub 2} wires. The devices were placed in a 4 K refrigerator to control at a certain temperature below T{sub c}. A scanning laser spot can be used by the combination of the XYZ piezo-drive stage and an optical fibre with an aspheric focused lens. The measurement system is fully controlled by LabVIEW based software. We succeeded in observing a line-and-space image of a meandering pattern by analysing response signals.

  15. MRI in late sequelae of Perthes' disease: imaging findings and symptomatology in ten hips

    International Nuclear Information System (INIS)

    Lahdes-Vasama, T.T.; Lamminen, A.E.; Marttinen, E.J.; Merikanto, J.E.O.

    1996-01-01

    Five painful (group A) and five symptomless (group B) hips in nine patients with late sequelae of Perthes' disease were studied with plain radiography and magnetic resonance imaging (MRI) in order to correlate MRI findings with symptomatology. The unaffected hips were also studied. In group A hips, poor congruence of the articular cartilage surfaces was present in three of five cases, whereas good congruence was found in all group B hips. In one spherical but painful hip (group A), MRI revealed a protuberance in the anterolateral cartilage of the femoral head. The joint cartilage in group A and B hips was, on average, 0.5 and 1.5 mm thicker, respectively, than the cartilage in the unaffected hips. The lateral joint capsule was, on average, 3.0 mm thicker in group A hips than in the unaffected hips (P < 0.05), which possibly reflects reactive changes due to chronic irritation in the painful hips. The mean joint capsule thickness differed by only 0.5 mm between the unaffected and group B hips. Mean anterior acetabular coverage by MRI was 97 % in group A and 98 % in group B, while in the unaffected hips mean anterior coverage was 102 %. In an aspherical painful hip, MRI revealed a juxta-articular cyst not visible by radiography. A symptomless intra-articular fragment, due to osteochondritis dissecans, was well visualized with MRI. MRI is recommended for evaluation of pain in hips with late sequelae of Perthes' disease. It may show abnormalities in bony structures, as well as in joint capsule and cartilage. (orig.). With 5 figs., 1 tab

  16. PARFUME Theory and Model basis Report

    Energy Technology Data Exchange (ETDEWEB)

    Darrell L. Knudson; Gregory K Miller; G.K. Miller; D.A. Petti; J.T. Maki; D.L. Knudson

    2009-09-01

    The success of gas reactors depends upon the safety and quality of the coated particle fuel. The fuel performance modeling code PARFUME simulates the mechanical, thermal and physico-chemical behavior of fuel particles during irradiation. This report documents the theory and material properties behind vari¬ous capabilities of the code, which include: 1) various options for calculating CO production and fission product gas release, 2) an analytical solution for stresses in the coating layers that accounts for irradiation-induced creep and swelling of the pyrocarbon layers, 3) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 4) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, and kernel migration (or amoeba effect), 5) two independent methods for determining particle failure probabilities, 6) a model for calculating release-to-birth (R/B) ratios of gaseous fission products that accounts for particle failures and uranium contamination in the fuel matrix, and 7) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. The accident condi¬tion entails diffusion of fission products through the particle coating layers and through the fuel matrix to the coolant boundary. This document represents the initial version of the PARFUME Theory and Model Basis Report. More detailed descriptions will be provided in future revisions.

  17. A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE OF CORE-COLLAPSE SUPERNOVAE. III. GRAVITATIONAL WAVE SIGNALS FROM SUPERNOVA EXPLOSION MODELS

    International Nuclear Information System (INIS)

    Müller, Bernhard; Janka, Hans-Thomas; Marek, Andreas

    2013-01-01

    We present a detailed theoretical analysis of the gravitational wave (GW) signal of the post-bounce evolution of core-collapse supernovae (SNe), employing for the first time relativistic, two-dimensional explosion models with multi-group, three-flavor neutrino transport based on the ray-by-ray-plus approximation. The waveforms reflect the accelerated mass motions associated with the characteristic evolutionary stages that were also identified in previous works: a quasi-periodic modulation by prompt post-shock convection is followed by a phase of relative quiescence before growing amplitudes signal violent hydrodynamical activity due to convection and the standing accretion shock instability during the accretion period of the stalled shock. Finally, a high-frequency, low-amplitude variation from proto-neutron star (PNS) convection below the neutrinosphere appears superimposed on the low-frequency trend associated with the aspherical expansion of the SN shock after the onset of the explosion. Relativistic effects in combination with detailed neutrino transport are shown to be essential for quantitative predictions of the GW frequency evolution and energy spectrum, because they determine the structure of the PNS surface layer and its characteristic g-mode frequency. Burst-like high-frequency activity phases, correlated with sudden luminosity increase and spectral hardening of electron (anti-)neutrino emission for some 10 ms, are discovered as new features after the onset of the explosion. They correspond to intermittent episodes of anisotropic accretion by the PNS in the case of fallback SNe. We find stronger signals for more massive progenitors with large accretion rates. The typical frequencies are higher for massive PNSs, though the time-integrated spectrum also strongly depends on the model dynamics.

  18. Application of 3-dimensional printing technology to construct an eye model for fundus viewing study.

    Directory of Open Access Journals (Sweden)

    Ping Xie

    Full Text Available To construct a life-sized eye model using the three-dimensional (3D printing technology for fundus viewing study of the viewing system.We devised our schematic model eye based on Navarro's eye and redesigned some parameters because of the change of the corneal material and the implantation of intraocular lenses (IOLs. Optical performance of our schematic model eye was compared with Navarro's schematic eye and other two reported physical model eyes using the ZEMAX optical design software. With computer aided design (CAD software, we designed the 3D digital model of the main structure of the physical model eye, which was used for three-dimensional (3D printing. Together with the main printed structure, polymethyl methacrylate(PMMA aspherical cornea, variable iris, and IOLs were assembled to a physical eye model. Angle scale bars were glued from posterior to periphery of the retina. Then we fabricated other three physical models with different states of ammetropia. Optical parameters of these physical eye models were measured to verify the 3D printing accuracy.In on-axis calculations, our schematic model eye possessed similar size of spot diagram compared with Navarro's and Bakaraju's model eye, much smaller than Arianpour's model eye. Moreover, the spherical aberration of our schematic eye was much less than other three model eyes. While in off- axis simulation, it possessed a bit higher coma and similar astigmatism, field curvature and distortion. The MTF curves showed that all the model eyes diminished in resolution with increasing field of view, and the diminished tendency of resolution of our physical eye model was similar to the Navarro's eye. The measured parameters of our eye models with different status of ametropia were in line with the theoretical value.The schematic eye model we designed can well simulate the optical performance of the human eye, and the fabricated physical one can be used as a tool in fundus range viewing research.

  19. Transepithelial photorefractive keratectomy with crosslinking for keratoconus.

    Science.gov (United States)

    Mukherjee, Achyut N; Selimis, Vasilis; Aslanides, Ioannis

    2013-01-01

    To analyse visual, refractive and topographic outcomes of combining transepithelial photorefractive keratectomy (tPRK) with simultan