Sample records for aspherical compound lens

  1. Scanning fiber-optic nonlinear endomicroscopy with miniature aspherical compound lens and multimode fiber collector

    Wu, Yicong; Xi, Jiefeng; Cobb, Michael J.; Li, Xingde


    A flexible scanning fiber-optic endomicroscope using a miniature compound lens and a multimode-fiber (MMF) collector was developed for two-photon fluorescence (TPF) and second-harmonic generation (SHG) imaging. The compound lens consisted of a pair of aspherical lenses and exhibited reduced chromatic aberration compared with gradient-index lenses, thus increasing the TPF/SHG collection efficiency. The introduction of a short MMF collector at the distal end of the double-clad fiber of the endo...

  2. Shape measurement of aspheric plastic lens with large angle

    Dagang Huang; Heng Zhang; Shah-Rong Lee; Baoguang Wang


    @@ In this paper, according to the features of easy distortion and scratch for aspheric plastic lens, a noncontact measuring method is raised to test error in shape of the lens. Namely, the distance between a template and its image reflected with tested lens can be measured in nearly the vertical direction of the lens axis when the two-dimensional (2D) template is put near the measured surface. Then, the outline of the central cross-section could be obtained by calculating and curve fitting. Furthermore, three-dimensional (3D) surface can be imitated through rotating the component. A new fitting method of drift measurement is presented to prevent reducing precision when the lens and the template are fixed. The template is adjusted according to the position of the lens. The measurement precision is in the order of magnitued of sub-microns. Rotationally symmetric convex aspheric surface with any angle can be measured by this method.

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

    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)

  4. The Simulation and Optimization of Aspheric Plastic Lens Injection Molding

    WEN Jialing; WEN Pengfei


    For the purpose of reducing the volumetric shrinkage and volumetric shrinkage variation, the process in injection molding of aspheric plastic lens was simulated, and several process parameters which include holding pressure, melt temperature, mold temperature, fill time, holding pressure time and cooling time were optimized by using an orthogonal experimental design method. Finally, the optimum process parameters and the influence degree of process parameters on the average volumetric shrinkage and the volumetric shrinkage variation are obtained.

  5. Residue stress analysis of molding aspherical plastic lens

    Hsu, Ming-Ying; Cheng, Yuan-Chieh; Chang, Shenq-Tsong; Huang, Ting-Ming


    The aspherical plastic lens is widely used in commercial optical products. Warpage and residue stress are two important factors that influence wavefront error. Several investigators have discussed warpage. We propose a methodology to study the effect of residue stress on wavefront error. Mold flow software was adopted to calculate the residue stress in injection processes. Optical software was used to find optical ray paths through the lens. Corresponding Optical Path Different (OPD) in each ray path was simulated by self-developed software. A 50-mm diameter plastic lens was used in this study. The mild- and high-frequency wavefront errors and the stress OPD effect at the injection area were found to be a result of the molding process. The proposed methodology was found to be very suitable for finding the effect of residue stress on wavefront error in plastic lenses.

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

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


    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.

  7. Research on the polishing technology of high-precision aspherical cylindrical lens

    Fu, Xiu-hua; Wang, Zhe; Jia, Zong-he; Dong, Huan; Liu, Dan; Zhang, Chuan-xin


    Aspherical cylindrical lens compared with the cylindrical lens, they improved image quality and optical properties, simplified the system architecture. They applied in many fields, such as high power laser system, fax machines and typographical scan imaging system, as well as bar code scanning, lighting and other aspects of holography. Aspherical cylindrical lens are centrosymmetric. It is difficult to process. Parallel with the side line and bus bar line is difficult to ensure. Machining accuracy is low. It is usually about 15 μm, that not sufficient to meet the needs of modern highprecision laser systems. These have become a major problem restricting its development. Combining traditional and modern polishing techniques, a new technique for polishing aspherical cylindrical lens is proposed-- longitudinal feedback compensation technology. With dimensions of 15 × 5 × 5 mm quartz aspherical cylindrical lens as an example, the surface profilometer results of detection of the workpiece usually, modify the shape of the polishing surface of the mold, to control the size of the area of the polishing, the surface of the workpiece to achieve the effect of the type of compensation. After repeated testing and feedback compensation, gradually improve the accuracy of the workpiece surface type. The results show that this technique can effectively improve the precision aspherical cylindrical lens. After detection the workpiece surface accuracy is 0.8μm, the surface finish is Class II. It has the actual production of a certain application value.

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

    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

  9. Problems in the application of a null lens for precise measurements of aspheric mirrors.

    Chkhalo, N I; Malyshev, I V; Pestov, A E; Polkovnikov, V N; Salashchenko, N N; Toropov, M N; Soloviev, A A


    Problems in the application of a null lens for surface shape measurements of aspherical mirrors are discussed using the example of manufacturing an aspherical concave mirror for the beyond extreme ultraviolet nanolithographer. A method for allowing measurement of the surface shape of a sample under study and the aberration of a null lens simultaneously, and for evaluating measurement accuracy, is described. Using this method, we made a mirror with an aspheric surface of the 6th order (i.e., the maximum deviation from the best-fit sphere is 6.6 μm) with the parameters of the deviations from the designed surface PV=5.3  nm and RMS=0.8  nm. An approximation of the surface shape was carried out using Zernike polynomials {Z(n)(m)(r,φ),m+n≤36}. The physical limitations of this technique are analyzed. It is shown that for aspheric measurements to an Angstrom accuracy, one needs to have a null lens with errors of less than 1 nm. For accurate measurements, it is necessary to establish compliance with the coordinates on the sample and on the interferogram. PMID:26835938

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

    Rodrigo França de Espíndola


    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.

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

    Yamanashi, Takanori


    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.

  12. Bionic optical imaging system with aspheric solid-liquid mixed variable-focus lens

    Du, Jia-Wei; Wang, Xuan-Yin; Liang, Dan


    A bionic optical imaging system with an aspheric solid-liquid mixed variable-focus lens was designed and fabricated. The entire system mainly consisted of a doublet lens, a solid-liquid mixed variable-focus lens, a connecting part, and a CCD imaging device. To mimic the structure of the crystalline lens, the solid-liquid mixed variable-focus lens consisted of a polydimethylsiloxane (PDMS) lens, a polymethyl methacrylate lens, and the liquid of ethyl silicone oil. By pumping liquid in or out of the cavity using a microinjector, the curvatures of the front and rear surfaces of the PDMS lens were varied, resulting in a change of focal length. The overall structure of the system was presented, as well as a detailed description of the solid-liquid mixed variable-focus lens, material, and fabrication process. Under different injection volumes, the deformation of the PDMS lens was measured and simulated, pictures were captured, and the optical performance was analyzed in simulations and experiments. The focal length of the system ranged from 25.05 to 14.61 mm, and the variation of the diopter was 28.5D, which was larger than that of the human eye.

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

    Jun-Hua Li


    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

  14. Optimum electrostatic force control for fabricating a hybrid UV-curable aspheric lens

    The purpose of this paper is to use a hybrid structure and the electrostatic force to fabricate aspheric lenses with high optical transmittance (95% at 405 nm). The hybrid structure is composed of Norland Optical Adhesive 63 (NOA63) (refractive index: 1.5802 at 405 nm) and BK-7 glass (refractive index: 1.5302). OSLO (Optics Software for Layout and Optimization) and CFD (Computational Fluid Dynamics) software packages were used to simulate the electric field gradient between the top and bottom electrodes and to produce the optimum bottom electrode design. Different electrode designs were also tested in order to optimize the morphology of the lens profile. The resulting lens profiles have clear apertures of approximately 0.92 mm with maximum shape errors of less than 0.18% and the spot size of the fabricated aspheric lenses can be controlled to approximately 0.504 µm. This technology can be used as a generic approach to fabricate lenses for applications in various micro-optical systems.

  15. Clinical performance of a new aspheric dual-optic accommodating intraocular lens

    Marques EF


    Full Text Available Eduardo F Marques,1 António Castanheira-Dinis2 1Department of Ophthalmology, Hospital da Cruz Vermelha, Lisboa, Portugal; 2Visual Sciences Research Centre, Universidade de Lisboa, Portugal Purpose: To describe the clinical performance of a new dual-optic intraocular lens (IOL with an enhanced optic profile designed to mimic natural accommodation.Patients and methods: Prospective multicenter clinical study with the new dual-optic aspheric accommodating IOL (Synchrony Vu in 74 patients (148 eyes undergoing cataract surgery. Refractive target was emmetropia. Examinations at 1 month and 6 months included subjective refractions; visual acuities at near, intermediate, and far; mesopic contrast sensitivity with and without glare; safety data; and subjective survey on dysphotopsia (halos and glare.Results: Clinical data at 6 months showed 89% of the eyes within ±1.0 D spherical equivalent refraction. Mean binocular uncorrected and distance-corrected visual acuity was 20/20 at far (0.00±0.11 logMAR and -0.06±0.08 logMAR, respectively, 20/20 at intermediate (0.01±0.13 logMAR and -0.01±0.10 logMAR, respectively, and 20/25 at near (0.10±0.14 logMAR and 0.14±0.15 logMAR, respectively. Mesopic contrast sensitivity was within normal limits. Seventy-eight percent of the patients had no spectacles and 70% had no dysphotopsia. One eye had IOL repositioning within 1 month of surgery.Conclusion: The new aspheric Synchrony Vu accommodating IOL provided good visual performance at a range of distances without affecting quality of vision and with minimal safety considerations. Keywords: accommodating IOL, cataract surgery, intraocular lens, presbyopia

  16. Theoretical and experimental research on error analysis and optimization of tool path in fabricating aspheric compound eyes by precision micro milling

    Chen, Mingjun; Xiao, Yong; Tian, Wenlan; Wu, Chunya; Chu, Xin


    Structure design and fabricating methods of three-dimensional (3D) artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes (ACEs) are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye (ACE) with surface roughness ( R a) below 0.12 μm is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.

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

    Francesco Semeraro


    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.

  18. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric,aberration correcting monofocal intraocular lens

    Florian; T; A; Kretz; Tamer; Tandogan; Ramin; Khoramnia; Gerd; U; Auffarth


    ·AIM: To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting,monofocal intraocular lens(IOL).·METHODS: Twenty-one patients(34 eyes) aged 50 to83 y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL(Tecnis ZCB00,Abbott Medical Optics). Three months after surgery they were examined for uncorrected(UDVA) and corrected distance visual acuity(CDVA), contrast sensitivity(CS)under photopic and mesopic conditions with and without glare source, ocular high order aberrations(HOA, Zywave II) and retinal straylight(C-Quant).· RESULTS: Postoperatively, patients achieved a postoperative CDVA of 0.0 log MAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27(primary coma components) and-0.04 ±0.16(spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed(P ≥0.28).· CONCLUSION: The implantation of an aspherical aberration correcting monofocal IOL after cataractsurgery resulted in very low residual higher order aberration(HOA) and normal straylight.

  19. Research on axisymmetric aspheric surface numerical design and manufacturing technology

    Wang, Zhen-zhong; Guo, Yin-biao; Lin, Zheng


    The key technology for aspheric machining offers exact machining path and machining aspheric lens with high accuracy and efficiency, in spite of the development of traditional manual manufacturing into nowadays numerical control (NC) machining. This paper presents a mathematical model between virtual cone and aspheric surface equations, and discusses the technology of uniform wear of grinding wheel and error compensation in aspheric machining. Finally, a software system for high precision aspheric surface manufacturing is designed and realized, based on the mentioned above. This software system can work out grinding wheel path according to input parameters and generate machining NC programs of aspheric surfaces.

  20. High brightness three-dimensional light field display based on the aspheric substrate Fresnel-lens-array with eccentric pupils

    Gao, Xin; Sang, Xinzhu; Yu, Xunbo; Cao, Xuemei; Chen, Zhidong; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan


    The brightness and viewing field of the reproductive three-dimensional (3D) image are crucial factors to realize a comfortable 3D perception for the light field display based on the liquid crystal device (LCD). To improve the illuminance of 3D image with sub-image-units with small aperture angles and enlarge the viewing field, the illuminance of the Fresnel-lens combining with the sub-images on LCD is analyzed and designed. Theoretical and experimental results show that the Fresnel-lens-array with eccentric pupil(FAEP) can address above problems. A 3D light field display based on LCD with FAEP and directional diffuser screen are used to reconstruct the target 3D field. 25 parallax sub-images are projected to the directional diffuser screen to verify the improvement of illuminance and viewing field. To reduce eccentric aberration introduced by eccentric pupil, a novel structure of Fresnel-lens-array is presented to reduce the aberration. The illuminance and viewing field are well promoted at the same time. 3D image with the high quality can be achieved.

  1. 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

    Rodrigo França de Espíndola


    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

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

    Leonardo Akaishi


    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

  3. Aspherical supernovae

    Kasen, Daniel Nathan


    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

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

    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


    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. PMID:25393218

  5. Design of Novel Compound Fresnel Lens for High-Performance Photovoltaic Concentrator

    Lei Jing; Hua Liu; Huifu Zhao; Zhenwu Lu; Hongsheng Wu; He Wang; Jialin Xu


    We present a new design of compound Fresnel-R concentrator which is composed of two lenses: a primary lens (Fresnel lens) that works by total internal reflection at outer sawteeth but refraction at inner sawteeth, and a ringed secondary lens that works by refraction. In contrast to previous Fresnel lens concentrators, this design increases the acceptance angle, improves the irradiance uniformity on the solar cell, and reduces the aspect ratio significantly. Meanwhile several sawteeth of the p...

  6. Design of Hartmann type null screens for testing a plano-convex aspheric lens with a CCD sensor inside the caustic.

    Castillo-Santiago, Gabriel; Castán-Ricaño, Diana; Avendaño-Alejo, Maximino; Castañeda, Luis; Díaz-Uribe, Rufino


    A new method to design Hartmann type null screens to test either qualitatively or quantitatively fast plano-convex aspherical lenses is presented. We design both radial and square null screens that produce arrays of circular spots uniformly distributed at predefined planes, considering that the CCD sensor is solely placed inside the caustic region. The designs of these null screens are based on knowledge of the caustic by refraction and on exact ray tracing. The null screens also serve to improve the alignment in optical systems. PMID:27557218

  7. The role of compound lens in optimizing the irradiation uniformity in longitudinal pumping laser

    Li Han-Ming; Li Ying-Jun; Zhang Jie


    In order to optimize the axial irradiation uniformity of a laser in plasma, this paper investigates the role played by the compound lens using a ray-tracing method. Obtained results show that the adoption of the compound lens is capable of increasing the axial line-focus length. Meanwhile, after the energy attenuation in the plasma has been considered,moderating the optical parameter of the compound lens to obtain the corresponding energy output to compensate for the attenuation optimizes the irradiation uniformity along the focal line.

  8. High transmission Ni compound refractive lens for high energy X-rays

    Brancewicz, M.; Itou, M.; Sakurai, Y.; Andrejczuk, A.; Chiba, S.; Kayahara, Y.; Inoue, T.; Nagamine, M.


    We present a new planar Ni compound refractive lens for high energy X-rays (116 keV). The lens is composed of identical plano-concave elements with longitudinal parabolic grooves manufactured by a punch technique. In order to increase the lens transmission, the thickness of the single lens at the parabolic groove vertex was reduced to less than 5 μm and the radius of curvature was reduced to about 20 μm. The small radius of curvature allowed us to reduce the number of single elements needed to get the focal length of 3 m to 54 single lenses. The gain parameter has been significantly improved compared to the previous lenses due to higher transmission, but the focused beam size and its gain are not as good as expected, mostly due to the aberrations caused by the lens shape imperfections.

  9. Possible application of compound Fresnel lens for neutron beam focusing

    We have developed a Fresnel-type focusing device for cold neutrons fabricated using single crystals of magnesium fluoride. This stacked-lens device using 50 elements (with 50 beam-bending interfaces) demonstrated a focal length of 5 m with a good transmission of 0.829 for 1.14 nm neutrons. The focused beam was 5 times more intense than a beam of the same spot size with the same final flight path length produced with the traditional pinhole collimation. The background-scattering noise from lens was an order of magnitude larger than that of the traditional pinhole collimation in the momentum range of 0.01-0.05 nm-1, almost 10-3 of focused direct beam at the lowest momentum transfers measurable. This device produced an intensity gain in measured SANS data of more than 10 times when compared with the conventional pinhole geometry with the same minimum momentum transfer

  10. Comparison of retinal image quality with spherical and customized aspheric intraocular lenses

    Guo, Huanqing; Goncharov, Alexander V.; Dainty, Chris


    We hypothesize that an intraocular lens (IOL) with higher-order aspheric surfaces customized for an individual eye provides improved retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis, ray-tracing eye models were used to investigate 10 designs of mono-focal single lens IOLs with rotationally symmetric spherical, aspheric, and customized surfaces. Retinal image quality of pseudo-phakic eyes using these IOLs together with individual variati...

  11. Projection-type X-ray microscope based on a spherical compound refractive X-ray lens

    Dudchik, Yu. I.; Gary, C. K.; Park, H; Pantell, R H; Piestrup, M. A.


    New projection- type X-ray microscope with a compound refractive lens as the optical element is presented. The microscope consists of an X-ray source that is 1-2 mm in diameter, compound X-ray lens and X-ray camera that are placed in-line to satisfy the lens formula. The lens forms an image of the X-ray source at camera sensitive plate. An object is placed between the X-ray source and the lens as close as possible to the source, and the camera shows a shadow image of the object. Spatial resol...

  12. Hard X-ray imaging by a spherical compound refractive lens

    Hard X-ray imaging by a spherical compound refractive lens is presented. The lens is composed of 123 biconcave microlenses with a size of 200 μm in diameter. Each microlens was formed by the epoxy between two bubbles, which were injected into an epoxy-filled glass capillary. The focal length of the lens is 114 mm at 8.05 keV. The light source was obtained by using a copper anode X-ray tube without a filter. The lens can be achieved a spatial resolution of 5 μm with field of view of about 700 μm, and 1-3 μm resolution may be obtainable by using monochromator and diaphragm.

  13. The generation of high precision aspherical surfaces in glass by CNC machining

    The design and production of an f/l aspheric focusing lens for a high-power laser system operating at 1054 nm is described. The relevant lens design parameters and the degree of flexibility in their choice are described and these, when carefully chosen, result in an extremely versatile lens with a large wavelength cover. The manufacture of the lens is also simplified. A comparison is made between the production of an aspheric surface by high quality conventional optical manufacturing processes and one generated and polished by a computer numerically controlled (CNC) jig grinding machine. (author)

  14. Focusing high-energy x-rays by a PMMA compound x-ray lens on Beijing synchrotron radiation facility

    Le Zi-Chun; Liang Jing-Qiu; Dong Wen; Zhu Pei-Ping; Peng Liang-Qiang; Wang Wei-Biao; Huang Wan-Xia; Yuan Qing-Xi; Wang Jun-Yue


    The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors' recent research on a polymethyl methacrylate (PMMA) compound x-ray lens. Firstly the designing and LIGA fabrication process for the PMMA compound x-ray lens are briefly described. Then, a method for theoretical analysis, as well as the experimental system for measurement is also introduced. Finally, the focusing spots for 8keV monochromatic x-rays by the PMMA compound x-ray lens are measured and analysed. According to the experimental results, it is concluded that the PMMA compound x-ray lens promises a good focusing performance under the high-energy x-rays.


    Yu. V. Dudchik


    Full Text Available Compound refractive lens was used for measuring size of 2-3 beamline Standford synchrotron radiation source and a size of microfocus X-ray tube. X-ray beam from the source was focused by the lens and parameters of the beam at image plane were measured. Scanning diaphragm and X-ray CCD-camera were used for measuring X-ray beam. It was found that the vertical size of synchrotron source is equal to 0,6 mm and the size of the X-ray tube focal spot is equal to 60 micrometers. 

  16. Microscope using an x-ray tube and a bubble compound refractive lens

    We present x-ray images of grid meshes and biological material obtained using an unfiltered x-ray tube and a compound refractive lens composed of microbubbles embedded in epoxy inside a glass capillary. Images obtained using this apparatus are compared with those using a synchrotron source and the same lens. We find that the field of view is larger than that obtained using the synchrotron source, whereas the contrast and resolution are reduced. Geometrical distortion around the edges of the field of view is also reduced. The experiments demonstrate the usefulness of the apparatus in a modest laboratory setting

  17. X-ray imaging of laser produced plasmas by a compound 3D x-ray lens

    Pilot scheme for the study of plasma under extreme condition is implemented using a compound 3D X-ray lens. Hard X-ray image of laser plasma produced by irradiating of copper foil by intense laser pulse was recorded using this lens

  18. Topological in-plane polarized piezo actuation for compact adaptive lenses with aspherical correction

    Lemke, Florian; Wallrabe, Ulrike; Wapler, Matthias C


    In this contribution, we investigate the effects of using in-plane polarized piezo actuators with topological buckling displacement to drive glass-piezo composite membranes for adaptive lenses with aspherical control. We find that the effects on the focal power and aspherical tuning range are relatively small, whereas the tuning speed is improved significantly with a first resonance of 1 kHz for a 13 mm aperture lens.

  19. Design of artificial spherical superposition compound eye

    Cao, Zhaolou; Zhai, Chunjie; Wang, Keyi


    In this research, design of artificial spherical superposition compound eye is presented. The imaging system consists of three layers of lens arrays. In each channel, two lenses are designed to control the angular magnification and a field lens is added to improve the image quality and extend the field of view. Aspherical surfaces are introduced to improve the image quality. Ray tracing results demonstrate that the light from the same object point is focused at the same imaging point through different channels. Therefore the system has much higher energy efficiency than conventional spherical apposition compound eye.

  20. The use of low departure aspheric surfaces in high quality wide angle lenses

    Dalzell, Kristen E.; Jonas, Reginald P.; Wallace, Brian P.


    Modern lens designs for digital sensors, such as those required in medium volumes for cinematography, often require the use of one or two high departure aspheric surfaces. With departures from best fit sphere of up to a few millimeters, the use of such surfaces are accompanied by a number of consequences: high cost metrology, very tight opto-mechanical tolerances and image artifacts due to the sub-aperture grinding and polishing process. Previously we examined the use of multiple aspheric surfaces with very low departures from best fit sphere (BFS) and concluded that advantages may be gained in standard and telephoto lenses, but not in wide angle lens designs1. In this work we consider the potential benefits of low departure aspheric surfaces, as applied to wide angle lenses in particular. We review the number, placement, and nature of aspheric surfaces in some wide angle lens design examples, and look at the potential to redesign with an increased number of low departure aspheric surfaces that have the potential to be manufactured without the need for computer generated holograms (CGH's). The use and limitations of modern interferometers capable of measuring aspheric surfaces without the use of CGH's will be considered. In one example we examine the performance, manufacturing, and cost perspective, paying particular attention to testing and mechanical alignment tolerances.

  1. A compound refractive lens for focusing high-energy X-rays

    The development of techniques for focusing X-rays has occupied physicists for more than a century. Refractive lenses, which are used extensively in visible-light optics, are generally considered inappropriate for focusing X-rays, because refraction effects are extremely small and absorption is strong. This has led to the development of alternative approaches based on bent crystals and X-ray mirrors, Fresnel and Bragg-Fresnel zone plates, and capillary optics (Kumakhov lenses). Here we describe a simple procedure for fabricating refractive lenses that are effective for focusing of X-rays in the energy range 5-40 keV. The problems associated with absorption are minimized by fabricating the lenses from low-atomic-weight materials. Refraction of X-rays by one such lens is still extremely small, but a compound lens (consisting of tens or hundreds of individual lenses arranged in a linear array) can readily focus X-rays in one or two dimensions. We have fabricated a compound lens by drilling 30 closely spaced holes (each having a radius of 0.3 mm) in an aluminium block, and we demonstrate its effectiveness by focusing a 14-keV X-ray beam to a spot size of 8 μm. (author)

  2. Pink-beam focusing with a one-dimensional compound refractive lens.

    Dufresne, Eric M; Dunford, Robert W; Kanter, Elliot P; Gao, Yuan; Moon, Seoksu; Walko, Donald A; Zhang, Xusheng


    The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments. Focusing the fundamental harmonics of an insertion device white beam increases the APS power density; here, a power density as high as 500 W mm(-2) was calculated. A CRL is chromatic so it does not efficiently focus X-rays whose energies are above the fundamental. Only the fundamental of the undulator focuses at the experiment. A two-chopper system reduces the power density on the imaging system and lens by four orders of magnitude, enabling imaging of the focal plane without any X-ray filter. A method to measure such high power density as well as the performance of the lens in focusing the pink beam is reported. PMID:27577759

  3. Thermal lens and all optical switching of new organometallic compound doped polyacrylamide gel

    Badran, Hussain Ali

    In this work thermal lens spectrometry (TLS) is applied to investigate the thermo-optical properties of new organometallic compound containing azomethine group, Dichloro bis [2-(2-hydroxybenzylideneamino)-5-methylphenyl] telluride platinum(II), doped polyacrylamide gel using transistor-transistor logic (TTL) modulated cw 532 nm laser beam as an excitation beam modulated at 10 Hz frequency and probe beam wavelength 635 nm at 14 mW. The technique is applied to determine the thermal diffusivities, ds/dT and the linear thermal expansion coefficient of the sample. All-optical switching effects with low background and high stability are demonstrated.

  4. Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

    Ladan Espandar


    Full Text Available Ladan Espandar1, Shameema Sikder2, Majid Moshirfar31Department of Ophthalmology, Tulane University, New Orleans, LA, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA; 3John A Moran Eye Center, University of Utah, Salt Lake City, UT, USAAbstract: Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL. The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.Keywords: hydrophilic acrylic intraocular lens, Softec HD intraocular lens, aspheric intraocular lens, IOL

  5. The fabrication of out of plane aspherical microlens arrays

    Zhang, Yong; Wang, Wanjun


    MOEMS (Micro-Opto-Elecro-Mechanical Systems) has brought new inspirations to the traditional optics design and manufacturing, due to their advantages such as micro sizes, low cost, good performance, easy to integrate, and mass production. From the microfabrication technology perspective, microlens is among the most difficult components to make, and it is also the most important component of all free space micro-optic components. In recent years, the aspherical lens with controllable curvature has become one of the most popular research subjects since it is helpful in eliminating aberration. In this paper, we report a new method of fabricating and replicating aspherical microlens array with primary optic axis in parallel with the substrate surface. The technology was based on ultra-violet (UV) lithography of SU-8 thick resist. A novel water bath oblique lithography technique was adopted. Diameter of the prototype microlenses fabricated is about 200 μm. By changing the pattern of mask and other process parameters, aspherical microlenses with different sizes and surface curvatures can be obtained. The microlens made using this technique has its main optical axis in parallel with the substrate, this makes it much easier to be integrated with other components into on-chip optical platforms such as optical switch and the imaging systems. This kind of micro-lens arrays will also be incorporated to microfluidic systems such as micro flow cytometry for fluorescence detections.

  6. Aspheric surface parameters measurement by Fizeau interferometer

    In this paper, a method for measurement the aspheric parameter by a Fizeau interferometer is presented. The aspheric surface can be a parabola, hyperbola or an ellipsoid. The main radiuse of curvature and eccentricity are the main parameters. The fringe patterns are analysed by phase shift method and the aspheric parameters are determined by fitting the aspheric function to the data. The experimental setup and measurement result will be presented.

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

    Kuo-Yung Hung


    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.

  8. Thermal lens and all optical switching of new organometallic compound doped polyacrylamide gel

    Hussain Ali Badran


    Full Text Available In this work thermal lens spectrometry (TLS is applied to investigate the thermo-optical properties of new organometallic compound containing azomethine group, Dichloro bis [2-(2-hydroxybenzylideneamino-5-methylphenyl] telluride platinum(II, doped polyacrylamide gel using transistor-transistor logic (TTL modulated cw 532 nm laser beam as an excitation beam modulated at 10 Hz frequency and probe beam wavelength 635 nm at 14 mW. The technique is applied to determine the thermal diffusivities, ds/dT and the linear thermal expansion coefficient of the sample. All-optical switching effects with low background and high stability are demonstrated.

  9. Development of a low cost high precision fabrication process for glass hybrid aspherical diffractive lenses

    The hybrid aspherical diffractive singlet achromat design can be used to reduce chromatic aberration in compact optical systems. In this paper, the development of a compression molded, low cost and high precision hybrid diffractive glass lens is described. Specifically, an aspherical diffractive lens designed to compensate for chromatic aberration was fabricated by precision glass molding. The diffractive features are integrated on the aspherical surface to avoid mold alignment during fabrication. As part of the effort to lower manufacturing cost, the diffractive profiles were directly fabricated by single-point diamond turning without polishing. A thin layer of platinum–iridium coating was applied to the mold surfaces to protect the mold inserts from degradation during the molding process. In order to reduce thermal shrinkage error, the hybrid lens was fabricated using a two-step precision molding process on a commercial glass molding machine. The geometry of the molded hybrid aspherical diffractive lens was measured using an optical profilometer and the results demonstrated a match to the design mold profile with a replication error of 0.16% in the radial direction and 6.3% in the axial direction. In addition, an optical metrology system to evaluate the diffraction efficiency and chromatic focal shift was constructed and the measured results showed that the hybrid lenses indeed function as designed

  10. 非球面晶状体与传统球面晶状体植入术后对比敏感度的研究%Contrast sensitivity of aspheric and standard spherical intraocular lens after phacoemulsification

    徐仁凤; 王理理; 黄振平; 吴勇


    目的:比较白内障术后早期非球面晶状体与传统球面晶状体植入术后功能视力.方法:白内障患者共50例,随机分成两组,一组患者植入以Acrysof IQ(Alcon)为代表的非球面晶状体,共23例 23眼;一组植入以AR40e(AMO)为代表的传统球面晶状体,共27例27眼.于术后1mo用CSV-1000E对比敏感度测试仪(由VECTOR VISION 公司提供)进行对比敏感度测定.结果:以Acrysof IQ (Alcon)为代表的非球面晶状体在6.12.18cpd时较以AR40e(AMO)为代表的传统球面晶状体能显著的提高患者对比敏感度.结论:以Acrysof IQ(Alcon)为代表的非球面晶状体可提高患者的功能视力%AIM:To compare the contrast sensitivity obtained through anterior surface modified prolate intraocular lens with the contrast sensitivity obtained through standard spherical intraocular Iens.METHODS:Patients presenting for cataract surgery in one eye were randomized to receive either the Acrysef IQ intraocular lens(AIcon)or the AR40e intraocular lens(AMO).50 eyes after phacoemulsification with IOL implantation were included,23 eyes received Acrysof IQ,and 27 eyes received AP40e intraocular lens (AMO).Contrast sensitivity testing under photopic conditions (85cd/m2)served as the prindpal outcome measure.The contrast sensitivity function was measured with CSV-1000E Vision Testing Instrument(provided by VECTOR ⅥSION COMPANY) at 30 days after surgery.RESULTS:The Acrysof IQ intraocular lens provided statistically significantly better contrast sensitivity at 6,12 and 18 cydes per degree under photopic conditions.CONCLUSION:The use of anterior surface modified prolate intraocular lens for cataract surgery has the potential to improve functional vision.

  11. Fast calculation of bokeh image structure in camera lenses with multiple aspheric surfaces

    Sivokon, V. P.; Thorpe, M. D.


    Three different approaches to calculation of internal structure of bokeh image in camera lenses with two aspheric surfaces are analyzed and compared - the transfer function approach, the beam propagation approach and direct raytracing in an optical design software. The transfer function approach is the fastest and provides accurate results when peak-to-valley of mid-spatial frequency phase modulation induced at the lens exit pupil is below λ/10. Aspheric surfaces are shown to contribute to the bokeh structure differently increasing the complexity of bokeh image especially for offaxis bokeh.

  12. ELID Grinding of Large Aspheric Optics Project

    National Aeronautics and Space Administration — Large aperture aspheric optics are among the most susceptible optical surfaces to the accumulation of periodic surface artifacts during fabrication. Periodic...

  13. Development of a compound focusing lens: improvement of signal-noise ratio

    We proposed a method to improve signal-noise ratio of the Fresnel-type neutron lens. The Gd mask of concentric circle thin layer reduced 80% noise, at the best, due to the Fresnel-type lens shape. As the transmission for 1.1 nm neutrons decreased from 0.83 to 0.79 by using the Gd mask, the loss was 0.04

  14. Extended formalism for simulating compound refractive lens-based x-ray microscopes

    Simons, Hugh; Poulsen, Henning Friis; Detlefs, Carsten


    We present a comprehensive formalism for the simulation and optimisation of CRLs in both condensing and full-field imaging configurations. The approach extends ray transfer matrix analysis to account for x-ray attenuation by the lens material. Closed analytical expressions for critical imaging parameters such as numerical aperture, vignetting, chromatic aberration and focal length are provided for both thin- and thick-lens imaging geometries.

  15. Comparison of contrast sensitivity and wavefront analysis 8fter implantation of AcrySof IQ aspherical intraocular lens%AcrySof IQ非球面人工晶状体植入后视觉质量观察

    罗敏; 计菁; 赵莼; 范先群; 潘燚蕾; 陆剑锋


    Objective To determine vision quality when testing two acrylic intraocular lenses,AcrySof IQ and AcrySof Natural,after routine cataract extraction and IOL implantation.Method Prospective,randomized,double-masked study that 260 eyes of 260 patients who underwent cataract extraction and IOL implantation was performed.Patients were randomly divided into 2 groups:AcrySof IQ or AcrySof Natural.One week,one and three month postoperative evaluations included contrast sensitivity and wavefront analysis.The independent-samples T test was used.P<0.05 was considered statistically significant.Result The AcrySof IQ group has significantly hisher and middle spatial frequency of contrast sensitivity.The difference in low spatial frequency was getting significant along with time.Patients with AcrySof IQ had a reduction in total high-order aberrations and spherical aberration.There were no difference in coma between two groups.Conclusion The use of aspheric acrylic AcrySof IQ IOL may improve the quality of vision as a result of the reduction of contrast sensitivity and spherical aberration.(Chin J Ophthalmol,2009,45:239-242)%目的 对比研究AcrySof IQ非球面人工晶状体和AcrySof Natural人工晶状体在年龄相关性白内障患者手术后的视觉质量.方法 前瞻性随机对照研究.选取年龄相关性白内障患者,按照双肓原则分为两组:IQ组和Natural组,分别植入AcrySof IQ和AcrySof Natural人工晶状体,其中IQ组:124只眼;Natural组:136只眼.术后观察两组患者的最佳矫正远视力、对比敏感度(CS)值、波阵面像差.采用统计软件SPSS 11.0进行数据分析,两组间术后视力采用重复测量方差分析,CS、波阵面像差采用具有一个重复测量两因素设计定量资料方差分析.结果术后1周、1个月、3个月采用CGT-1000 CS眩光测试仪检查发现两组间的CS值在中、高空间频率段均有差异(F值范围5.05~26.47,P<0.05),低频空间两组间差异随时间推移逐渐明显.

  16. A method to design aspheric spectacles for correction of high-order aberrations of human eye

    LI Rui; WANG ZhaoQi; LIU YongJi; MU GuoGuang


    Aiming at the correction of high-order aberrations of human eye with spectacles,a design method of aspheric spectacles is proposed based on the eye's wavefront aberrations data.Regarding the eyeball and the spectacles as a whole system-the lens-eye system-the surface profiles of the spectacles are achieved by optimization procedure of lens design.Different from the conventional optometry,in which the refraction prescription is acquired with a visual chart,the design takes into account the two aspects of actual human viewing,eyeball rolling and certain distinct viewing field.The rotation angle of eyeball is set to be ±20° as wearing spectacles,and the field of view is set to be ∧7° which is especially important as watching screen display.The individual eye model is constructed as the main part of the lens-eye system.The Liou eye model is modified by sticking a thin meniscus lens to the crystalline lens.Then the defocus of the individual eye is transferred to the front surface of the meniscus lens,and the astigmatism and high-order aberrations are transferred to the front surface of the cornea.50 eyes are involved in this research,among which 36 eyes have good enough visual performance already after sphero-cylindrical correction.10 eyes have distinct improvement in vision and 4 eyes have no visual improvement by further aspheric correction.6 typical subject eyes are selected for the aberrations analysis and the spectacles design in this paper.It is shown that the validity of visual correction of aspheric lens depends on the characteristics of the eye's wavefront aberrations,and it is effective for the eye with larger astigmatism or spherical aberration.Compared with sphero-cylindrical correction only,the superiority taken by the aspheric correction is mainly on the improvement of MTF at a larger field of view.For the best aspheric correction,the MTF values increase by 18.87%,38.34%,44.36%,51.29% and 57.32% at the spatial frequencies of 40

  17. Design and realization of an aspherical doublet

    Melich, Radek; Matela, M.; Procháska, František; Psota, Pavel; Matoušek, Ondřej; Tomka, David

    Vol. 9442. Bellingham : SPIE-INT SOC OPTICAL ENGINEERING , 2015 - (Kovačičinová, J.; Vít, T.), 94420U-94420U ISBN 978-1-62841-557-5. ISSN 0277-786X. - (SPIE). [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA TA ČR(CZ) TA03010843 Institutional support: RVO:61389021 Keywords : aspherical surface * asphere measurements * optical design * ZEMAX * aspherical optical production Subject RIV: JP - Industrial Processing

  18. 非球面多焦点人工晶状体植入术后视觉质量的临床研究%Visual quality after aspherical multifocal intraocular lens implantation

    李莉; 刘晶


    目的 比较2种多焦点人工晶状体IQ ReSTOR+3 D和IQ ReSTOR +4 D的临床效果.方法 选择年龄相关性白内障患者32例(41眼)行白内障超声乳化吸除联合人工晶状体植入术,其中IQ ReSTOR+3 D组15例(20眼),IQ ReSTOR +4 D组17例(21眼),比较术后3个月2组患者的远距离、中距离和近距离视力、对比敏感度、视野、离焦曲线和生活问卷调查结果.结果 术后3个月,IQ ReSTOR+3 D组裸眼中距离视力为1.38±0.06,优于IQ ReSTOR +4 D组(1.07±0.09),差异有统计学意义(P<0.05).2组间近距离和远距离视力差异均无统计学意义(均为P>0.05).离焦曲线IQ ReSTOR+3 D组在-1.5 D、-2.0 D、-2.5D的视力均优于IQ ReSTOR +4 D组,差异均有统计学意义(均为P<0.05).结论 IQ ReSTOR+3 D较IQ ReSTOR+4 D能够提供更好的中距离视力和一定距离范围的近视力.%Objective To compare the clinical effects after implantation of multi-focal lens (MIOL) between IQ ReSTOR + 3 D and IQ ReSTOR + 4 D. Methods Random clinical study of 32 patients (41 eyes) age-related cataract patients underwent phacoemulsification and IOL implantation, 15 patients (20 eyes) in IQ ReSTOR + 3 D group and 17 patients (21 eyes) in IQ ReSTOR +4 D. At 3 months after cataract surgery, the distant,intermediate and near visual acuities,contrast sensitivity,visual fields,defocus testing and questionnaires in two groups were observed. Results At postoperative 3 months, the uncorrected intermediate visual acuity of IQ ReSTOR + 3 D group was 1.38 ±0.06,which was much better than that of IQ ReSTOR+4 D group 1.07 ±0.09, there was statistical difference (P 0.05). The defocus testing showed the visual acuity at -1.5 D, -2. 0 D, -2. 5 D in IQ ReSTOR +3 D group were better than that of IQ ReSTOR + 4 D group, there were statistical differences (all P < 0.05). Conclusion The diffractive multifocal IOL with a + 3 D add power provides significantly better intermediate visual acuity and a plateau of optimum near

  19. Fabrication of compound refractive lens using soft and deep X-ray lithography beamline on Indus-2

    X-ray compound refractive lenses (CRL) have been fabricated using Soft and Deep X-ray lithography (SDXRL) beamline on Indus-2. Upto 50 parabolic lenses are fabricated in PMMA using 1X X-ray mask. The mask contains of 20 micron thick gold absorbing pattern on polyimide membrane. The lens fabrication is done by exposing 500 μm thick PMMA sheets to 5-12keV X-rays from Indus-2. The fabricated CRL will be suitable for generating focused X-ray beam of Indus-2 bending magnet source.

  20. Measuring aspheres with a chromatic Fizeau interferometer

    Seifert, L.; Pruss, C.; Dörband, B.; Osten, W.


    The established method to measure aspherical surfaces is interferometric testing with null optics, but due to economical reasons the applications are limited. A special null optic has to be calculated, fabricated and qualified for each individual type of asphere. This time- and money consuming method is only cost-efficient for large quantities or when tests require high accuracy. We propose a new and flexible technique for measuring an ensemble of different aspheres with only one measurement setup. The main idea is to use the wavelength as a tunable parameter. Because it is possible to change the wavelength without introducing new errors by mechanical movements, the wavelength variation results in a higher measurement flexibility without reducing the measurement accuracy. We present the chromatic Fizeau Interferometer with a diffractive element as null-optic for the measurement of a set of four aspheres. We will show the influence of unwanted diffraction orders and the expected measurement accuracy. As in the monochromatic setup, especially the area around the optical axis is problematic and can not be measured with the desired accuracy. The use of a small aperture stop on the optical axis is recommended because errors in other radial domains are filtered as well. The results show, that the chromatic Fizeau interferometer makes the established monochromatic method far more flexible and that different aspheres can be measured in the same setup.

  1. Effect of germination time on proximate analysis, bioactive compounds and antioxidant activity of lentil (Lens culinaris Medik. sprouts

    A. Ahmed Fouad


    Full Text Available Background. The lentil plant, Lens culinaris L., is a member of the Leguminoceae family and constitutes one of the most important traditional dietary components. The purpose of the current study was to investigate the effects of sprouting for 3, 4, 5 and 6 days on proximate, bioactive compounds and antioxidative characteristics of lentil (Lens culinaris sprouts. Material and methods. Lentil seeds were soaked in distilled water (1:10, w/v for 12 h at room temperature (~25°C, then kept between thick layers of cotton cloth and allowed to germinate in the dark for 3, 4, 5 and 6 days. The nutritional composition, protein solubility, free amino acids, antinutritional factors, bioactive compounds and antioxidant activity of raw and germinated samples were determined using standard official procedures. Results. Sprouting process caused significant (P ≤ 0.05 increases in moisture, protein, ash, crude fiber, protein solubility, free amino acids, total, reducing and nonreducing sugars. However, oil content, antinutritional factors (tannins and phytic acid significantly (P ≤ 0.05 decreased. Results indicated that total essential amino acids of lentil seeds protein formed 38.10% of the total amino acid content. Sulfur-containing amino acids were the first limiting amino acid, while threonine was the second limiting amino acid in raw and germinated lentil seeds. Sprouting process has a positive effect on the essential amino acid contents and protein efficiency ratio (PER of lentil sprouts. Phenolics content increased from 1341.13 mg/100 g DW in raw lentil seeds to 1411.50, 1463.00, 1630.20 and 1510.10 in those samples germinated for 3, 4, 5 and 6 days, respectively. Sprouted seeds had higher DPPH radical scavenging and reducing power activities. Conclusions. Based on these results, sprouting process is recommended to increase nutritive value, and antioxidant activity of lentil seeds.

  2. Patient acceptability of the Tecnis® multifocal intraocular lens

    Sood, Priyanka; Woodward, Maria A.


    Cataract surgery has evolved. The goal of the surgeon includes both restoration of vision and refinement of vision. Patients’ desire for spectacle independence has driven the market for presbyopia-correcting cataract surgery and development of novel intraocular lens (IOL) designs. The Tecnis® Multifocal Intraocular Lens incorporates an aspheric, modified anterior prolate IOL with a diffractive multifocal lens design. The design aims to minimize spherical aberration and improve range of focus....

  3. Aspherical bubble dynamics and oscillation times

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


    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.

  4. Deterministic finishing of aspheric optical components

    Lambropoulos, Teddy; Fess, Ed; DeFisher, Scott


    Manufacturing aspheric optics can present challenges depending on the complexity of their shape. This is especially true during the finishing stage. To tackle this challenge, OptiPro Systems has developed two technologies for deterministic optical polishing: UltraForm Finishing (UFF) and UltraSmooth Finishing (USF). UFF is a deterministic sub aperture polishing process that polishes spherical, aspheric, and free form surface geometries. In contrast, the USF process is a deterministic mid to large size aperture polishing process that works with a conforming lap. These two technologies have the ability to tackle a wide range of optical shapes by removing sub-surface damage, removing various mid-spatial frequency artifacts that might be left from a grinding process, and correct the optic's figure error in a controlled fashion. This presentation will describe these technologies, present performance information as to their capabilities, and show how OptiPro is developing these technologies to push the state of the art in manufacturing.

  5. Precision grinding of micro-aspherical surface

    Suzuki, Hirofumi; Shibutani, Hideo; Higuchi, Toshiro; Horiuchi, Osamu


    Recently, micro aspherical glass lenses are required for electric devices, optical devices and advanced optical fiber transmission equipments. The glass lenses are manufactured with glass molding method by using ceramics dies such as tungsten carbide and therefore molding dies are most important. The ceramics molding dies must be ground ultra-precisely with micro diamond wheel. In this report, our developed micro grinding methods/systems are discussed according to a variety of the workpiece shapes.

  6. Ductile grinding of ultraprecise aspherical optical lenses

    Koenig, Wilfried; Sinhoff, Volker


    The manufacturing of glass lenses has always set exacting requirements on the finishing technique. If, in addition, the design deviates from the conventional geometry of plane and sphere, the standard manufacturing process of rough grinding with cup-wheels and subsequent precision grinding and polishing with reproductive techniques fails. In order to achieve highest form accuracies and surface qualities combined with a flexible surface shape, ductile single- point-grinding meets the requirements for the production of rotationally symmetric aspheres.

  7. A theoretical design of gradient index multifocal contact lens for correcting presbyopia and an attempt to elicit its performance using ray tracing

    Bakaraju, Ravi C.; Ehrmann, Klaus; Papas, Eric B.; Ho, Arthur


    We propose a novel theoretical design of gradient index (GRIN) multifocal contact lens (MFCL) to compensate presbyopia and make predictions regarding its performance on a schematic model eye and to compare its performance with conventional aspheric progressive MFCL.


    Petrov, P. V.; Kolchevsky, N.N.


    Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.

  9. Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

    Ladan Espandar; Shameema Sikder; Majid Moshirfar


    Ladan Espandar1, Shameema Sikder2, Majid Moshirfar31Department of Ophthalmology, Tulane University, New Orleans, LA, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA; 3John A Moran Eye Center, University of Utah, Salt Lake City, UT, USAAbstract: Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD™ lens is an aspheric, hydrophilic acrylic intraocular le...

  10. Patient acceptability of the Tecnis® multifocal intraocular lens

    Woodward, Maria


    Priyanka Sood1, Maria A Woodward21Emory Eye Center, Atlanta, GA, USA; 2Kellogg Eye Center, Ann Arbor, MI, USAAbstract: Cataract surgery has evolved. The goal of the surgeon includes both restoration of vision and refinement of vision. Patients' desire for spectacle independence has driven the market for presbyopia-correcting cataract surgery and development of novel intraocular lens (IOL) designs. The Tecnis® Multifocal Intraocular Lens incorporates an aspheric, modified anter...

  11. Thermal lens diagnostics and mitigation in diode end pumped lasers

    Stučinskas, Darius


    In this thesis, analysis of thermal effects and various approaches for their mitigation in diode end pumped ultrafast lasers is presented. Experimental investigations were performed by employing Shack-Hartmann wavefront sensor which was adapted for measurements of thermal lens in diode end pumped lasers. During research, operation of high average power, diode-pumped, Nd:YVO4 laser with aspheric aberration corrector was investigated. Actual thermal lens measurements were conducted in order to ...

  12. Sub-nanometer interferometry for aspheric mirror fabrication

    Aspheric mirrors for extreme ultraviolet lithography (EUVL) at a wavelength of 13nm require surface figure accuracy approaching 0.10 nm rms. A new type of interferometry, based on the fundamental process of diffraction, is described that has the intrinsically ability to achieve this accuracy on aspherical surfaces. However, care must be taken in the design and implementation of the optical system that images the aspheric mirror onto the CCD camera. Non-common paths of the measurement and reference wavefronts within the optical system, as well as distortion of the image of aspheric mirror on the CCD, must be addressed in order to realize sub-nanometer accuracy. The phase shifting diffraction interferometer and the mitigation of potential imaging errors are described for measuring the surface figure on aspheric mirrors

  13. Novel automated process for aspheric surfaces

    Bingham, Richard G.; Walker, David D.; Kim, Do-Hyung; Brooks, David; Freeman, Richard; Riley, Darren


    We report on the development of a novel industrial process, embodied in a new robotic polishing machine, for automatically grinding an polishing aspheric optics. The machine is targeted at meeting the growing demand for inexpensive axially symmetric but aspherical lenses and mirrors for industry and science, non-axisymmetric and conformal optics of many kinds, the planarization of silicon wafers and associated devices, and for controlling form and texture in other artifacts including prosthetic joints. We describe both the physics and the implementation of the process. It is based on an innovative pressurized tool of variable effective size, spun to give high removal rate. The tool traverse and orientation are orchestrated in a unique (and patented) way to avoid completely the characteristic fast peripheral-velocity and center-zero left by conventional spinning tools. The pressurized tooling supports loose abrasive grinding and polishing, plus a new bound-abrasive grinding process, providing for a wide range of work from coarse profiling to fine polishing and figuring. Finally we discuss the critical control, data handling and software challenges in the implementation of the process, contrast the approach with alternative technologies, and present preliminary results of polishing trials.

  14. The design and fabrication of common optical components lithography lens

    Huang, Jiun-Woei


    The design and fabrication of common optical components lithography Lens has been carried out for a 1 to 1 stepper. The specification of lens is fulfilled the 3-D lithography system as 2 micron in resolution for 1 inch x 2.8 inches system. The lens has been sophistically designed by dual path in a triplet to reduce the number of components. A single aspherical surface has been applied to reduce the aberration to diffraction limit in lens. The well-made shapes of lens have been suggested. Then, the fabrication of lens has been in the process. Finally, the optical axis of tolerance optical mechanical mountings for lens system in assembly has been analyzed, and valuable for assembly and fabrication.

  15. Additive manufacturing of a trifocal diffractive-refractive lens

    Hinze, Ulf; El-Tamer, Ayman; Doskolovich, Leonid L.; Bezus, Evgeni A.; Reiß, Stefan; Stolz, Heinrich; Guthoff, Rudolf F.; Stachs, Oliver; Chichkov, Boris


    The application of two-photon polymerization and molding for the fabrication of a multifocal diffractive-refractive lens operating in water is studied. The fabricated lens is of aspheric shape and combines diffractive and refractive parts in a single element to generate three foci. The lens performance is characterized by visualization of the beam propagation in a transparent basin filled with water containing fluorescein. The experimental measurements are in good agreement with the theoretical description. The obtained results are promising for the realization of trifocal intraocular lenses with predetermined light intensity distribution between the foci.

  16. An Instrument for Inspecting Aspheric Optical Surfaces and Components Project

    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...

  17. An Instrument for Inspecting Aspheric Optical Surfaces and Components Project

    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...

  18. Mechanically tunable aspheric lenses via additive manufacture of hanging elastomeric droplets for microscopic applications

    Fuh, Yiin-Kuen; Chen, Pin-Wen; Lai, Zheng-Hong


    Mechanically deformable lenses with dynamically tunable focal lengths have been developed in this work. The fabricated five types of aspheric polydimethylsiloxane (PDMS) lenses presented here have an initial focal length of 7.0, 7.8, 9.0, 10.0 and 10.2 mm. Incorporating two modes of operation in biconvex and concave-convex configurations, the focal lengths can be tuned dynamically as 5.2-10.2, 5.5-9.9, 6.6-11.9, 6.1-13.5 and 6.6-13.5 mm respectively. Additive manufacturing was utilized to fabricate these five types of aspheric lenses (APLs) via sequential layering of PDMS materials. Complex structures with three-dimensional features and shorter focal lengths can be successfully produced by repeatedly depositing, inverting and curing controlled PDMS volume onto previously cured PDMS droplets. From our experiments, we empirically found a direct dependence of the focal length of the lenses with the amount (volume) of deposited PDMS droplets. This new mouldless, low-cost, and flexible lens fabrication method is able to transform an ordinary commercial smartphone camera into a low-cost portable microscope. A few microscopic features can be readily visualized, such as wrinkles of ladybird pupa and printed circuit board. The fabrication technique by successively applying hanging droplet and facile mechanical focal-length-tuning set-up can be easily adopted in the development of high-performance optical lenses.

  19. Refractive lens for hard x-rays

    The refractive lens for hard X-rays on the base of glass capillary is presented. The fabrication techniques for lens production are described. The model of refractive lens for hard X-ray is proposed. The model assume that the compound lens work similar one thin lens the complex refraction index of which is following: n=1-δ N + i β N. On the base of this model the parameters of focussed beam are calculated and the images of object are constructed

  20. Optimal strategy for fabrication of large aperture aspheric surfaces.

    Feng, Yunpeng; Cheng, Haobo; Wang, Tan; Dong, Zhichao; Tam, Hon-Yuen


    Aspheric surfaces are widely used because of their desirable characteristics. Such a surface can obtain nearly perfect imaging quality with fewer optical elements and reduce the size and mass of optical systems. Various machine systems have been developed based on modern deterministic polishing technologies for large aperture aspheric surfaces. Several factors affect the final precision of large aperture aspheric surfaces, such as the velocity limit of the machine and the path design. Excess velocity, which will be truncated automatically by the computer numerical control system, may cause the dwell time to deviate from the desired time. When a path designed on a two-dimensional surface map with equidistant pitch is projected onto an aspheric surface, the pitch changes as a result of the varied curvature of the aspheric surface. This may affect the removal map and cause some ripple errors. A multiregion distribution strategy, which includes velocity checking, is proposed in this study to avoid exceeding the velocity limits. The strategy can be used to modify local errors and edge effects. A three-dimensional spiral path generation method is also presented using an iterative method to ensure uniformity in the space length of the adjacent circle of the spiral path. This process can reduce the ripple error caused by the overlapping of tool paths. A polishing experiment was conducted, and the results proved the validity of the proposed strategies. PMID:24514001

  1. Patient acceptability of the Tecnis® multifocal intraocular lens

    Sood P


    Full Text Available Priyanka Sood1, Maria A Woodward21Emory Eye Center, Atlanta, GA, USA; 2Kellogg Eye Center, Ann Arbor, MI, USAAbstract: Cataract surgery has evolved. The goal of the surgeon includes both restoration of vision and refinement of vision. Patients' desire for spectacle independence has driven the market for presbyopia-correcting cataract surgery and development of novel intraocular lens (IOL designs. The Tecnis® Multifocal Intraocular Lens incorporates an aspheric, modified anterior prolate IOL with a diffractive multifocal lens design. The design aims to minimize spherical aberration and improve range of focus. The purpose of this review is to assess patient acceptability of the Tecnis® multifocal intraocular lens.Keywords: Tecnis®, intraocular lens, multifocal, presbyopia 

  2. Agronomic Management under Organic Farming May Affect the Bioactive Compounds of Lentil (Lens culinaris L. and Grass Pea (Lathyrus communis L.?

    Valeria Menga


    Full Text Available A two year field experiment was carried out to evaluate the effects of three row and eight row seeding on the total phenolic compound (TPC, total flavonoid content (TFC, hydrolyzed (HTC and condensed tannin (CTC, antioxidant activity (ABTS assay, protein content and soluble dietary fiber (SDF and insoluble dietary fiber (IDF in the extracts of lentil (Lens culinaris L. and grass pea (Lathyrus communis L. cultivated under organic farming. The aim of this study was to determine whether row spacing used for seeding in organic farming systems for lentil and grass pea is a suitable method to increase the accumulation of antioxidant compounds in these crops. Grass pea showed the highest mean SDF and protein while lentil varieties showed the greatest and significant content of all of the antioxidant compounds. In lentil, there were increases in TPC (52%, HTC (73%, TFC (85% and CTC (41%, passing from three rows to eight rows, while in grass pea, the increases were lower, and only significant for TFC and CTC (37%, 13% respectively. In both lentils and grass pea, the highest correlation coefficient was between TPC and HTC, which indicates that the HTC includes the predominant phenolic compounds in lentil as well as in grass pea (r = 0.98, 0.71 p < 0.001, respectively. Regardless of legume species, TPC, HTC, TFC and CTC showed significant (p < 0.001 and linear correlations with the ABTS assay. These data confirm the key role of row spacing for the improvement of the antioxidant properties of lentil in organic farming; moreover, they hint at the major responsiveness and adaptation of lentil to environmental stimulus with respect to grass pea.

  3. Polishing of S-FPL-53 Aspherical Lenses

    Poláková, Ivana; Procháska, František; Klepetková, Eva

    Vol. 9442. Bellingham : SPIE-INT SOC OPTICAL ENGINEERING , 2015 - (Kovačičinová, J.; Vít, T.), s. 944213-944213 ISBN 978-1-62841-557-5. ISSN 0277-786X. - (SPIE). [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : polishing * asphere * S-FPL-53 * aspherical surface Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  4. Metrology for the production process of aspheric lenses

    Beutler, Andreas


    Metrology revealing the form deviation of an aspheric surface is a fundamental part of all different production processes of aspheric lenses. Different processing steps have different requirements for the production. A selection of measuring instruments commonly applied in these processes is presented. This contains tactile and optical pointwise measuring instruments and laser interferometer systems. The principle functionality and the properties are presented. An overview of the application of these systems in different production processes is given. In order to show comparability, measuring results of the different types of systems are presented.

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

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


    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

  6. A New Locus Shaping Method of Quadric Aspheric Parts

    WANG Yuan-sheng; WANG He-yan; LU Gui-ying; CAI Li; PIAO Cheng-gao


    The original idea and shaping principle of locus shaping method for processing the aspheric optical parts are introduced, and the partial structure of the machine tool designed is described. The method has the advantage of high efficiency and low cost compared to the numerical control method. And it is proven that the method is feasible.

  7. Preparation of Core-Shell Hybrid Compounds by Atomic Transfer Radical Polymerization and Its Application to Plastic Lens of Headlamp.

    Noh, Seung-Man; Ahn, Jae-Beum; Choi, Ki-Hyun; Park, Seung-Kyu


    Nano silica ball (NSB) core polymethylmethacrylate (PMMA) shell hybrid nanocomposites were synthesized by atomic transfer radical polymerization (ATRP) method for the application to the clearcoat to enhance scratch resistance. The characteristics of the synthesized inorganic/organic hybrid material were examined by scanning electron microscope (SEM), particle size analysis, Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis-differential scanning calorimetry (TGA-DSC). The scratch resistance and light transmittance of the clearcoat were measured by a nano-scratch tester and UV-visible spectroscopy, respectively. The average particle size of the NSB-PMMA hybrid compounds was 30 nm with narrow size distribution. Even 0.1 wt% loading of NSB-PMMA in the clearcoat dramatically enhanced the scratch resistance, about 40% increase in the force of the first fracture, while slightly reduced the light transmittance, about 5% only. PMID:26716303

  8. Enhanced optical power of GaN-based light-emitting diode with compound photonic crystals by multiple-exposure nanosphere-lens lithography

    Zhang, Yonghui; Wei, Tongbo, E-mail:; Xiong, Zhuo; Shang, Liang; Tian, Yingdong; Zhao, Yun; Zhou, Pengyu; Wang, Junxi; Li, Jinmin [Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)


    The light-emitting diodes (LEDs) with single, twin, triple, and quadruple photonic crystals (PCs) on p-GaN are fabricated by multiple-exposure nanosphere-lens lithography (MENLL) process utilizing the focusing behavior of polystyrene spheres. Such a technique is easy and economical for use in fabricating compound nano-patterns. The optimized tilted angle is decided to be 26.6° through mathematic calculation to try to avoid the overlay of patterns. The results of scanning electron microscopy and simulations reveal that the pattern produced by MENLL is a combination of multiple ovals. Compared to planar-LED, the light output power of LEDs with single, twin, triple, and quadruple PCs is increased by 14.78%, 36.03%, 53.68%, and 44.85% under a drive current 350 mA, respectively. Furthermore, all PC-structures result in no degradation of the electrical properties. The stimulated results indicate that the highest light extraction efficiency of LED with the clover-shape triple PC is due to the largest scattering effect on propagation of light from GaN into air.

  9. Fresnel Lens

    Watson, Michael D.; Scott, Steve; Lamb, David; Zimmerman, Joe E. (Technical Monitor)


    Fresnel lenses span the full range of sizes from lens a few micrometers in diameter to lens several meters in diameter. These lenses are utilized in various fields including optical communication, theatrical lighting, office equipment, video entertainment systems, solar concentrators, and scientific research instruments. These lenses function either as diffractive or refractive optical elements depending on the geometrical feature size of the lens. The basic functions of these lenses is described followed by an overview of fabrication methods. A summary of applications is then provided illustrating the rich variety of applications for which fresnel lenses may be designed to fulfill.

  10. Use of very low departure aspheric surfaces in high quality camera lenses

    Dalzell, Kristen E.; Jonas, Reginald P.; Thorpe, Michael D.


    High performance, compact cinematography lenses working over a large sensor area are demanding designs which are achieved using one or two high departure aspheric elements. With sag departures from best fit sphere of up to a few millimeters, the use of such aspheres is accompanied by a number of consequences. These include high cost metrology, very tight opto-mechanical tolerances and the potential for image artifacts produced during the sub-aperture grinding and polishing process. A modified asphere manufacturing process was utilized to reduce artifacts by eliminating the subaperture grinding and pre-polishing. This method is limited to aspheric surfaces which can be directly polished from a spherical base surface with aspheric departures of <15μm. These very low departure aspheres have the benefit of inexpensive metrology and tolerance relaxation compared with high departure aspheres. Interferograms, slope maps, and out-of-focus images demonstrate the feasibility and advantages of direct asphere generation from a polished sphere. A series of large format lenses covering focal lengths from telephoto to wide angle, were redesigned to determine the feasibility of the use of very low departure aspheres. Increasing the number of aspheric surfaces but reducing the aspheric departure to less than 15μm was demonstrated. We conclude that 3-5 very low departure aspheres are sufficient to provide similar performance to the high departure asphere designs for most focal lengths. One limitation encountered was in the wide angle lenses. The exception was the wide angle lenses where it is difficult to reduce departures below 30μm while maintaining the same optical performance.

  11. Outdoor overall performance of a novel air-gap-lens-walled compound parabolic concentrator (ALCPC) incorporated with photovoltaic/thermal system

    Highlights: • A prototype of an ALCPC-PV/T system was designed and set up. • Good optical agreements were observed between simulation and experiment. • The effects of the temperature on the electrical characteristics were discussed. • The thermal performance for circulating cooling was analyzed. • The system efficiency was calculated to present the overall performance. - Abstract: A novel air-gap-lens-walled compound parabolic concentrator incorporated with photovoltaic/thermal system (ALCPC-PV/T) was proposed. The optical, electrical and thermal performances of the ALCPC-PV/T under the outdoor condition were analyzed for building integrated concentrating photovoltaic/thermal application. The simulation and experiment were carried out to reveal the optical characteristics of ALCPC-PV/T on two typical days. The experiment results verified the optical simulation results that the ALCPC-PV/T system had a half acceptance angle of 35° and an average optical efficiency of 83.0% within the half acceptance angle for direct incidence. Furthermore, the average optical efficiencies on the two typical days were all above 60% under the actual outdoor condition considering direct and diffuse solar radiation. Details of electrical characteristics affected by the temperature of circulating cooling water were also displayed. The electrical and thermal efficiencies of the ALCPC-PV/T system during the test were 6.0% and 35.0% respectively with the final water temperature of 70 °C. In addition, the fitted results indicated that under the zero reduced temperature condition, the thermal efficiency of the ALCPC PV/T system was 52.0%, and the corresponding electrical efficiency was 6.6%

  12. Lens customization method to minimize aberration in integral imaging

    Miranda, Matheus; Kim, Jonghyun; Hong, Keehoon; Lee, Byoungho


    Conventionally the elemental lenses of the lens-array used in integral imaging have spherical surface profiles, thus they suffer from intrinsic lens aberrations such as spherical aberration and astigmatism. Aberrations affect the ability of the lens to focus light in a single point, or to collimate light from a point source. In integral imaging, this results in a loss of image quality of the reconstructed image due to distortions. The viewing characteristics of the integral imaging system, such as viewing angle and image resolution, are also affected by aberrations. We propose the use of a custom made aspherical lens-array which was specifically designed to minimize distortions due to aberrations and hence improve the reconstructed image quality. Ray optics calculations are used in order to analyze the aberrations and find the initial lens surface profile. Lens optimization is performed with the aid of numerical simulation software. The designed lens-array is compared to a conventional spherical lens-array of same properties. The design, optimization, and fabrication processes are described and the experiments are presented and compared with the computer simulations.

  13. Manufacturing of high-precision aspherical and freeform optics

    Hoogstrate, André M.; van Drunen, Casper; van Venrooy, Bart; Henselmans, Rens


    Aspherical and freeform optical elements have a large potential in reducing optical aberrations and to reduce the number of elements in complex high performance optical systems. However, manufacturing a single piece or a small series of aspherical and freeform optics has for long been limited by the lack of flexible metrology tools. With the cooperative development of the NANOMEFOS metrology tool by TNO, TU/e and VSL, we are able to measure the form of aspheres and freeforms up to 500 mm in diameter with an accuracy better than 10 nm rms. This development opened the possibility to exploit a number of iterative, corrective manufacturing chains in which manufacturing technologies such as Single Point Diamond Turning, freeform grinding, deterministic polishing and classical polishing are combined in an iterative loop with metrology tools to measure form deviation (like CMM, LVDT contact measurement, interferometry and NANOMEFOS). This paper discusses the potentials, limitations and differences of iterative manufacturing chains used by TNO in the manufacturing of high performance optics for astronomical purposes such as the anufacturing of the L2 of the Optical Tube Assembly of the four laser-guide star facility of the ESO VLT, Manufacturing of Aluminium freeforms mirrors for the SCUBA-2 instrument. Based on these results we will give an outlook into the new challenges and solutions in manufacturing high-precision optics.

  14. Measurement of large aspheric surfaces by annular subaperture stitching interferometry

    Xiaokun Wang; Lihui Wang; Longhai Yin; Binzhi Zhang; Di Fan; Xuejun Zhang


    A new method for testing aspheric surfaces by annular subaperture stitching interferometry is introduced.It can test large-aperture and large-relative-aperture aspheric surfaces at high resolution, low cost, and high efficiency without auxiliary null optics. The basic principle of the method is described, the synthetical optimization stitching model and effective algorithm are established based on simultaneous least-square fitting. A hyperboloid with an aperture of 350 mm is tested by this method. The obtained peak-to-valley (PV) and root-mean-square (RMS) values of the surface error after stitching are 0.433λ and 0.052λ (λis 632.8 nm), respectively. The reconstructed surface map is coincide with the entire surface map from null test, and the difference of PV and RMS errors between them are 0.031λ and 0.005λ, respectively.This stitching model provides another quantitive method for testing large aspheric surfaces besides null compensation.

  15. Simulation analysis of grinding wheel motion trajectory on SiC ceramics aspheric surface grinding

    Zhang, Feihu; Liu, Lifei; Li, Chunhui


    In grinding process of SiC ceramics aspheric surface, the motion trajectory of grinding wheel has great influence on the surface forming. The paper provides mathematical models of grinding wheel movements; analytical simulation was done to describe the trajectories of the grinding wheel in manufacturing an aspherical workpiece. The effect of grinding parameters (including the rotation speed of the workpiece, the feed rate of grinding wheel etc.) on the aspheric surface coverage rate was conducted and discussed in detail. An experimental study was done according to the simulation results and an aspheric surface with form error less than 10μm was gained.

  16. Lens Model

    Nash, Ulrik William


    Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of probabil......Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of...... probabilistic functionalism, and concerns the environment and the mind, and adaptation by the latter to the former. This entry is about the lens model, and probabilistic functionalism more broadly. Focus will mostly be on firms and their employees, but, to fully appreciate the scope, we have to keep in mind the...

  17. Finite Element Analysis of the LOLA Receiver Telescope Lens

    Matzinger, Elizabeth


    This paper presents the finite element stress and distortion analysis completed on the Receiver Telescope lens of the Lunar Orbiter Laser Altimeter (LOLA). LOLA is one of six instruments on the Lunar Reconnaissance Orbiter (LRO), scheduled to launch in 2008. LOLA's main objective is to produce a high-resolution global lunar topographic model to aid in safe landings and enhance surface mobility in future exploration missions. The Receiver Telescope captures the laser pulses transmitted through a diffractive optical element (DOE) and reflected off the lunar surface. The largest lens of the Receiver Telescope, Lens 1, is a 150 mm diameter aspheric lens originally designed to be made of BK7 glass. The finite element model of the Receiver Telescope Lens 1 is comprised of solid elements and constrained in a manner consistent with the behavior of the mounting configuration of the Receiver Telescope tube. Twenty-one temperature load cases were mapped to the nodes based on thermal analysis completed by LOLA's lead thermal analyst, and loads were applied to simulate the preload applied from the ring flexure. The thermal environment of the baseline design (uncoated BK7 lens with no baffle) produces large radial and axial gradients in the lens. These large gradients create internal stresses that may lead to part failure, as well as significant bending that degrades optical performance. The high stresses and large distortions shown in the analysis precipitated a design change from BK7 glass to sapphire.

  18. Asphericity of the human cornea for different corneal diameters

    González-Méijome, José Manuel; Villa-Collar, César; Montés-Micó, Robert; Gomes, Antonio


    PURPOSE: To measure the anterior corneal asphericity (Q) with different corneal diameters. SETTING: Department of Physics (Optometry), University of Minho, Braga, Portugal. METHODS: Thirty-six eyes of 36 patients were evaluated using a videokeratoscope, and the Q-values were recorded. Topographic data were also analyzed using Vol-CT 6.89 software (Sarver & Associates, Inc) to obtain the Q-values with different corneal diameters (3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, and 7.0 mm). Variable Q models o...

  19. Research on process technology of off-axis ellipsoid aspheric mirror

    Liu, Dongmei; Ma, Ke; Jia, Zonghe


    In recent years, the off-axis aspheric surface is widely used in wide coverage and high-resolution space optical systems. In this paper, research on processing technology of high precision and high efficiency off-axis ellipsoid aspheric mirror was studied deeply. With the help of CNC milling and polishing machine, off-axis ellipsoid aspheric mirror with diameter of 58mm was developed, by optimizing the concentration of polish liquid, grinding size, machining direction and other process parameters, based on the disadvantage of traditional processing that off-axis aspheric is easy to generate edge splitting and secondary surface damage, a new processing method "vertical off-axis ellipsoid aspheric surface processing method" was put forward. This method not only ensures the accuracy of work piece of optical axis, surface accuracy and accuracy of the edge, but also reduces secondary surface damage, improves processing efficiency and achieves high precision and high efficiency processing of off-axis ellipsoid aspheric surface, which is conducive to mass production. Through the detection of off-axis ellipsoid aspheric mirror by Taylor Profiler , surface accuracy (PV value) is 0.1981μm, the aspheric surface finish is level II and the optical axis accuracy is 0.01mm that it meets the requirements.

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

    Meyer B; Sluyterman van Langeweyde G; Wottke M


    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: Retrospect...

  1. High numerical aperture silicon collimating lens for mid-infrared quantum cascade lasers manufactured using wafer-level techniques

    Logean, Eric; Hvozdara, Lubos; Di Francesco, Joab; Herzig, Hans Peter; Voelkel, Reinhard; Eisner, Martin; Baroni, Pierre-Yves; Rochat, Michel; Müller, Antoine


    We present an aspheric collimating lens for mid-infrared (4-14 µ) quantum cascade lasers. The lenses were etched into silicon by an inductively coupled plasma reactive ion etching system on wafer level. The high refractive index of silicon reduces the height of the lens prole resulting in a simple element working at high numerical aperture (up to 0.82). Wafer level processes enable the fabrication of about 5000 lenses in parallel. Such cost-eective collimating lens is a step towards the adopt...

  2. High precision metrology of domes and aspheric optics

    Murphy, Paul E.; Fleig, Jon; Forbes, Greg; Tricard, Marc


    Many defense systems have a critical need for high-precision, complex optics. However, fabrication of high quality, advanced optics is often seriously hampered by the lack of accurate and affordable metrology. QED's Subaperture Stitching Interferometer (SSI®) provides a breakthrough technology, enabling the automatic capture of precise metrology data for large and/or strongly curved (concave and convex) parts. QED"s SSI complements next-generation finishing technologies, such as Magnetorheological Finishing (MRF®), by extending the effective aperture, accuracy and dynamic range of a phase-shifting interferometer. This workstation performs automated sub-aperture stitching measurements of spheres, flats, and mild aspheres. It combines a six-axis precision stage system, a commercial Fizeau interferometer, and specially developed software that automates measurement design, data acquisition, and the reconstruction of the full-aperture figure error map. Aside from the correction of sub-aperture placement errors (such as tilts, optical power, and registration effects), our software also accounts for reference-wave error, distortion and other aberrations in the interferometer"s imaging optics. The SSI can automatically measure the full aperture of high numerical aperture surfaces (such as domes) to interferometric accuracy. The SSI extends the usability of a phase measuring interferometer and allows users with minimal training to produce full-aperture measurements of otherwise untestable parts. Work continues to extend this technology to measure aspheric shapes without the use of dedicated null optics. This SSI technology will be described, sample measurement results shown, and various manufacturing applications discussed.

  3. Systematic uncertainties from halo asphericity in dark matter searches

    Although commonly assumed to be spherical, dark matter halos are predicted to be non-spherical by N-body simulations and their asphericity has a potential impact on the systematic uncertainties in dark matter searches. The evaluation of these uncertainties is the main aim of this work, where we study the impact of aspherical dark matter density distributions in Milky-Way-like halos on direct and indirect searches. Using data from the large N-body cosmological simulation Bolshoi, we perform a statistical analysis and quantify the systematic uncertainties on the determination of local dark matter density and the so-called J factors for dark matter annihilations and decays from the galactic center. We find that, due to our ignorance about the extent of the non-sphericity of the Milky Way dark matter halo, systematic uncertainties can be as large as 35%, within the 95% most probable region, for a spherically averaged value for the local density of 0.3-0.4 GeV/cm 3. Similarly, systematic uncertainties on the J factors evaluated around the galactic center can be as large as 10% and 15%, within the 95% most probable region, for dark matter annihilations and decays, respectively

  4. Decentration of a spectacle lens

    Bartkowska, Janina


    The correct placing of the lenses plays an important role in the ophthalmological practice. Centering errors cause disadvantageous prismatic effects and worsen image quality. The optical axes of the spectacles should pass by rotation centers of the eyes. An often met error consists in a faulty center distance, in a wrong positioning of the lenses axis or their placing too high, too low, or in the inclining without lowering. The errors reach some millimeters and some degrees of arc. In technical optics acceptable errors are fractions or hundredths of millimeters and minutes or seconds of arc. Therefore only first powers of decentration are taken into account. In the spectacle optics one cannot omit the second powers of decentration vector. An astigmatism proportional to the square of decentration arises in the center of the field. The off axis aberrations are a quadratic function of the decentration with linear term. The aberrations are calculated by admitting a virtual diaphragm in the point of intersection of the lens axis with the eye's view axis. This method can be applied also to the lenses with aspheric surface and to astigmatic lenses, if the decentration vector lies in one of the principal sections of toroidal surface.

  5. Optical design of an aspherical cylinder-type reflecting solar concentrator

    In this paper a highly efficient solar concentrating mirror is presented. A part of the aspherical cylinder's inner wall defined by a set of specific coefficients a2, a4, a6, a8, a10, a12, a14, a16 and C is used as reflective surfaces of concentrating mirror. Based on the particular aspherical equation and the optical law of reflection, the relationship between the direction vectors of the sunlight beams reflected from the cylindrical inner wall and the coefficients of an aspherical equation, a2, a4, a6, a8, a10, a12, a14, a16 and C has been derived. By optimizing these coefficients, the Sunbeams incident on the aspherical cylinder's inner wall can be focused on a very narrow line segment parallel to the cylindrical busbar and form a linear focus (focal line). The particular set of coefficients associated with the particular aspherical equation is obtained by using particle swarm optimization algorithm. The focusing effect of the solar concentrating mirror with respect to the particular set of coefficients is demonstrated by using computer simulations and the experiment. The theoretical results show that this solar concentrating mirror has a light compression ratio of about 285 to 1. The linear spot can be used as a strong light source or a high temperature heat source. - Highlights: • A part of the aspherical cylinder's inner wall is used as a concentrating mirror. • The relationship between direction vectors of reflected Sunbeams and aspheric coefficients. • The particular set of aspheric coefficients obtained with particle swarm optimization algorithm. • The Sunbeams can be focused on a very narrow line segment parallel to the cylindrical busbar. • The aspheric cylindrical concentrating mirror has a light compression ratio of 285 to 1

  6. Chromatic aberration elimination for digital rear projection television L-type lens by genetic algorithms

    Fang, Yi-Chin; Liu, Tung-Kuan; Wu, Bo-Wen; Chou, Jyh-Horng; MacDonald, John


    Following the development of a digitalized image optics system, chromatic aberration has become increasingly important especially in lateral color aberration. For rear projection television L-type lens, chromatic aberration plays the significant role because it is easily seen when facing bright screen. Basically, the elimination of axial chromatic and lateral color aberration for an optical lens depends on the choice of optical glass. DLS (damped least squares), a Ray-tracing-based method, is limited, owing to its inability to identify an enhanced optical system configuration. Genetic algorithms were applied to so-called global optimization but unfortunately so far the results show little success. Additionally, L-type optics with aspherical surface might complicate optimization due to being nonlinear response during optimization. As an alternative, this research proposes a new feasible chromatic aberration optimization process by using algorithms involving theories of geometric optics in a lens, real encoding, multiple dynamic crossover and random gene mutation techniques. In this research, rear projection television lens with aspherical surface and L-type lens are mainly discussed. Results and conclusions show that attempts to eliminate difficult axial and lateral color aberration are successful.

  7. Milking the spherical cow: on aspherical dynamics in spherical coordinates

    Pontzen, Andrew; Teyssier, Romain; Governato, Fabio; Gualandris, Alessia; Roth, Nina; Devriendt, Julien


    Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analysis of observational data. The assumption leads to an exact conservation of angular momentum for every particle, making the dynamics unrealistic. But how much does that inaccuracy matter in practice for analyses of stellar distribution functions, collisionless relaxation, or dark matter core-creation? We provide a general answer to this question for a wide class of aspherical systems; specifically, we consider distribution functions that are "maximally stable", i.e. that do not evolve at first order when external potentials (which arise from baryons, large scale tidal fields or infalling substructure) are applied. We show that a spherically-symmetric analysis of such systems gives rise to the false conclusion that the density of particles in phase space is ergodic (a function of energy alone). Using this idea we are able to demonstra...

  8. Critical phenomena in the aspherical gravitational collapse of radiation fluids

    Baumgarte, Thomas W


    We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical solution in spherically symmetric collapse, find evidence for its universality, and study the approach to this critical solution in the absence of spherical symmetry. For the cases that we consider, aspherical deviations from the spherically symmetric critical solution decay in damped oscillations in a manner that is consistent with the behavior found by Mart\\'in-Garc\\'ia and Gundlach in perturbative calculations. Our simulations are performed with an unconstrained evolution code, implemented in spherical polar coordinates, and adopting "moving-puncture" coordinates.

  9. Very large computer generated holograms for precision metrology of aspheric optical surfaces Project

    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...

  10. The Effect of the Asphericity of Myopic Laser Ablation Profiles on the Induction of Wavefront Aberrations

    Bühren, Jens; Nagy, Lana; Yoon, Geunyoung; MacRae, Scott; Kohnen, Thomas; Huxlin, Krystel R.


    A PMMA model study showed that spherical aberration induction in laser refractive surgery is due to loss of ablation efficiency in the corneal periphery. Aspheric ablation induced less spherical aberration and provided better theoretical image quality.

  11. Integration of Full-Spectrum Metrology and Polishing for Rapid Production of Large Aspheres Project

    National Aeronautics and Space Administration — We propose to design, build, and test a major new instrument capable of both measuring and polishing the surface of aspheric mirrors up to 1.2 meters in diameter,...

  12. Research on geometric model of grinding large and medium scales optical aspheric surfaces

    Kang, Nianhui; Li, Shengyi; Zheng, Ziwen


    Aspheric optics have been used in optical systems widely because of their excellent optical properties. At present, the manufacture of small scale aspheric surfaces has been industrialized. However the manufacture of large and medium aspheric surfaces still follows the procedure of grinding, lapping and polishing. Generally speaking, increasing the working efficiency is the key of machining large and medium scale aspheric surfaces. As we know, lapping and polishing have relatively low efficiencies. Therefore prior to lapping and polishing, NC grinding is often used to shape large and medium scale optical aspheric surfaces, so as to reduce the subsequent process time. Current approaches to grinding aspheric surfaces differ from each other because the wheels and methods used are different, which is inconvenient for programming. To facilitate programming, a unified mathematical formulation is proposed for calculation of the wheel center trajectory when grinding axisymmetric aspheric surfaces based on the principle of shaping aspheric surfaces. Certain geometric models are derived from the unified formulation for the cases of parallel grinding wheel, spherical grinding wheel and cup grinding wheel, according to their features of process. The condition of avoiding overcutting is also derived. The step length of cutting is adaptively selected with accuracy control so as to reduce the program codes. After analyze all the factors affecting the shape accuracy of the curved surface, the major factors are found to be the tool setting error and the radius error of the grinding wheel, then the corresponding influence coefficients of the errors are calculated and the simulation results are given. Finally an example is shown in order to prove the analysis.

  13. Contact lens in keratoconus

    Varsha M Rathi


    Full Text Available Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP lenses, soft and soft toric lenses, piggy back contact lenses (PBCL, hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

  14. Research on precision grinding processing and compensation finishing experiment for mid-large- aperture square aspheric optical element

    Nie, Fengming; Li, Zhanguo; Wang, Dasen; Zhang, Guangping; Guo, Chengjun; Pei, Ning; Li, Yupeng


    This paper analyzes dot-line envelope grinding principle, which is applicable to mid-large- aperture square aspheric optical element, determines the mathematical process control model based on X/Y/C three-axis aspheric grinding machine, We develop the appropriate high-precision aspheric grinding manufacturing and measurement systems software, using the plane grinding wheel to do the grinding experiments and the repeated compensation processing experiment. The experiments show that: high-precision aspheric grinding manufacturing and measurement systems software can be realized axisymmetric aspheric high-precision machining control and measurement; using compensation processing of the X/Y/C three-axis aspheric grinding machine which can effectively improve the precision PV value, surface error from the initial processing of the PV value :12 μm to the compensation processing of the PV value :3 μm .

  15. Accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline GRIN lens.

    Sheil, Conor J; Goncharov, Alexander V


    The purpose of this manuscript is to introduce a new age-dependent model of the human lens with two GRIN power distributions (axial and radial) that allow decoupling of its refractive power and axial optical path length. The aspect ratio of the lens core can be held constant under accommodation, as well as the lens volume by varying the asphericity of the lens external surfaces. The spherical aberration calculated by exact raytracing is shown to be in line with experimental data. The proposed model is compared to previous GRIN models from the literature, and it is concluded that the features of the new model will be useful for GRIN reconstruction in future experimental studies; in particular, studies of the accommodation-dependent properties of the ageing human eye. A proposed logarithmic model of the lens core enables decoupling of three fundamental optical characteristics of the lens, namely axial optical path length, optical power and third-order spherical aberration, without changing the external shape of the lens. Conversely, the near-surface GRIN structure conforms to the external shape of the lens, which is necessary for accommodation modelling. PMID:27231637

  16. Asphericity and clumpiness in the winds of Luminous Blue Variables

    Davies, B; Vink, J S; Davies, Ben; Oudmaijer, Rene D.; Vink, Jorick S.


    We present the first systematic spectropolarimetric study of Luminous Blue Variables (LBVs) in the Galaxy and the Magellanic Clouds, in order to investigate the geometries of their winds. We find that at least half of our sample show changes in polarization across the strong H$\\alpha$ emission line, indicating that the light from the stars is intrinsically polarized and therefore that asphericity already exists at the base of the wind. Multi-epoch spectropolarimetry on four targets reveals variability in their intrinsic polarization. Three of these, AG Car, HR Car and P Cyg, show a position angle (PA) of polarization which appears random with time. Such behaviour can be explained by the presence of strong wind-inhomogeneities, or `clumps' within the wind. Only one star, R 127, shows variability at a constant PA, and hence evidence for axi-symmetry as well as clumpiness. However, if viewed at low inclination, and at limited temporal sampling, such a wind would produce a seemingly random polarization of the typ...

  17. Grinding aspheric and freeform micro-optical molds

    Tohme, Yazid E.


    Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

  18. Use of a NOM profilometer to measure large aspheric surfaces

    Pearson, John L.; Roberts, Gareth W.; Rees, Paul C. T.; Thompson, Samantha J.


    The use of autocollimator-based profilometers of the Nanometer Optical measuring Machine (NOM) design has been reported for the evaluation of X-ray optics for some time. We report a related development in the use of a non-contact NOM profilometer for the in situ measurement of base radius of curvature and conic constant for E-ELT primary mirror segments during fabrication. The instrument is unusual in NOM design in that it is deployable onto a CNC polishing machine in an industrial fabrication environment. Whilst the measurement of radius of curvature of spherical surfaces over a single scan has been reported previously, here we report on the use of this instrument to measure optical surfaces with an aspheric departure of 180 micrometers using a grid of multiple scans and bespoke surface fitting software. The repeatability of the measurement has been found to be approximately 1 mm in a measured radius of curvature of approximately 90 m. The absolute accuracy is limited by the accuracy of the calibration of the autocollimator and the in situ calibration of the instrument during operation.

  19. Comparison of contact and non-contact asphere surface metrology devices

    DeFisher, Scott; Fess, Edward M.


    Metrology of asphere surfaces is critical in the precision optics industry. Surface metrology serves as feedback into deterministic grinding and polishing platforms. Many different techniques and devices are used to qualify an asphere surface during fabrication. A contact profilometer is one of the most common measurement technologies used in asphere manufacturing. A profilometer uses a fine stylus to drag a diamond or ruby tip over the surface, resulting in a high resolution curved profile. Coordinate measuring machines (CMM) apply a similar concept by touching the optic with a ruby or silicon carbine sphere. A CMM is able to move in three dimensions while collecting data points along the asphere surface. Optical interferometers use a helium-neon laser with transmission spheres to compare a reflected wavefront from an asphere surface to a reference spherical wavefront. Large departure aspheres can be measured when a computer generated hologram (CGH) is introduced between the interferometer and the optic. OptiPro Systems has developed a non-contact CMM called UltraSurf. It utilizes a single point non-contact sensor, and high accuracy air bearings. Several different commercial non-contact sensors have been integrated, allowing for the flexibility to measure a variety of surfaces and materials. Metrology of a sphere and an asphere using a profilometer, CMM, Interferometer with a CGH, and the UltraSurf will be presented. Cross-correlation of the measured surface error magnitude and shape will be demonstrated. Comparisons between the techniques and devices will be also presented with attention to accuracy, repeatability, and overall measurement time.

  20. Non-contact optical measurement of lens capsule thickness during simulated accommodation

    Ziebarth, Noel; Manns, Fabrice; Acosta, Ana-Carolina; Parel, Jean-Marie


    Purpose: To non-invasively measure the thickness of the anterior and posterior lens capsule, and to determine if it significantly changes during accommodation. Methods: Anterior and posterior capsule thickness was measured on post-mortem lenses using a non-contact optical system using a focus-detection technique. The optical system uses a 670nm laser beam delivered to a single-mode fiber coupler. The output of the fiber coupler is focused on the tissue surface using an aspheric lens (NA=0.68) mounted on a translation stage with a motorized actuator. Light reflected from the sample surface is collected by the fiber coupler and sent to a photoreceiver connected to a computer-controlled data acquisition system. Optical intensity peaks are detected when the aspheric lens is focused on the capsule boundaries. The capsule thickness is equal to the distance traveled between two peaks multiplied by the capsule refractive index. Anterior and posterior lens capsule thickness measurements were performed on 18 cynomolgus (age average: 6+/-1 years, range: 4-7 years) eyes, 1 rhesus (age: 2 years) eye, and 12 human (age average: 65+/-16, range: 47-92) eyes during simulated accommodation. The mounted sample was placed under the focusing objective of the optical system so that the light was incident on the center pole. Measurements were taken of the anterior lens capsule in the unstretched and the stretched 5mm states. The lens was flipped, and the same procedure was performed for the posterior lens capsule. Results: The precision of the optical system was determined to be +/-0.5um. The resolution is 4um and the sensitivity is 52dB. The human anterior lens capsule thickness was 6.0+/-1.2um unstretched and 4.9+/-0.9um stretched (p=0.008). The human posterior lens capsule was 5.7+/-1.2um unstretched and 5.7+/-1.4um stretched (p=0.974). The monkey anterior lens capsule thickness was 5.9+/-1.9um unstretched and 4.8+/-1.0um stretched (p=0.002). The monkey posterior lens capsule was 5

  1. Contact Lens Solution Toxicity

    ... rash and rashes clinical tools newsletter | contact Share | Contact Lens Solution Toxicity Information for adults A A A This image shows a reaction to contact lens solution. The prominent blood vessels and redness ...

  2. Research on complex grinding and lapping of micro-aspheric surface

    Guo, Yinbiao; Lin, Feilong


    Aiming at several problems existing in micro-aspheric component manufacture field in china recently, this paper brings forward a new complex grinding and lapping method that is used in producing micro-aspheric optical workpiece. This method adopts a complex wheel which integrates micro-grinding and MRF technique. The structure and parameters of the new pattern-grinding wheel are analyzed. The course of processing is summarized and every steps of controlling system are introduced. Methods about solving technical difficulties of process are put forward. The new complex processing method can increase flexility, processing efficiency and precision of the manufacture system, and provide a feasible way to resolve shortages of the micro-aspheric component manufacture domain.

  3. Ultraprecision finishing of micro-aspherical surface by ultrasonic assisted polishing; Technical Digest

    Suzuki, Hirofumi; Kawamori, Ryota; Yamamoto, Yuji; Miyabara, Mitsuru; Okino, Tadashi; Hijikata, Yoshio; Moriwaki, Toshimichi


    Micro aspherical glass lenses are required for electronic devices, optical devices and advanced optical fiber transmission equipments. The glass lenses are manufactured by glass molding method by using micro ceramics dies such as tungsten carbide or silicon carbide (1). Therefore molding dies are most important and they were ground by ultra-precision grinding method with diamond wheel. Recently, the wavelength of used laser is becoming shorter and then the accuracies of the micro molding die are required to be much more precise (2). In this paper, ultrasonic assisted polishing methods/systems were developed in order to finish micro aspherical dies that were ground with micro diamond wheel. In the polishing experiments, the molding die of tungsten carbide was polished with diamond abrasives to test the basic polishing characteristics and the aspheric die was polished with proposed ultrasonic assisted polishing method.

  4. Design of aspherical surfaces for panoramic imagers using multi-populations genetic algorithm

    Wang, Li-Ping; Liang, Zhong-zhu; Jin, Chun-Shui


    A design method of aspherical surface for panoramic imaging system with two mirrors using multi-populations genetic algorithms is proposed. Astigmatism induced by mirrors may significantly compromise image resolution. To solve this problem, we induced algebraic expression of astigmatism in panoramic imager based on generalized Coddington equation and theory of geometric optics. Then, we propose an optimization process for mirror profile design to eliminate astigmatism and provide purposely-designed projection formula with aid of MPGA. A series of polynomial expressions of aspherical surfaces are obtained and procedures of the design are presented. In order to facilitate ray tracing and aberration calculation, even asphere surface model is obtained by using of hybrid schemes combining MPGA and damped least squares. Finally, a prototype of the catadioptric panoramic imager has been developed and panoramic ring image is obtained.

  5. Scanning pupil approach to aspheric surface slope error tolerancing in head-up display optics

    Sivokon, V. P.


    We present a novel approach to tolerancing slope errors of aspheric surfaces in relay optics of typical avionics head-up displays (HUD). In these systems, a beamlet entering the pilot eye occupies only a tiny fraction of HUD entrance pupil/eyebox with a typical diameter of 125mm. Consequently the beam footprint on any HUD optical surface is a small fraction of its clear aperture. This presents challenges to HUD tolerancing which is typically based on parallax (angular difference in line of sight between left and right eyes) analysis. Aspheric surfaces manufactured by sub-aperture grinding/polishing techniques add another source of error - surface slope error. This type of error not only degrades image quality of observed HUD symbology but also leads to its "waviness" and "floating" especially noticeable when a pilot moves his head within the HUD eyebox. The suggested approach allows aspheric surface slope error tolerancing that ensures an acceptable level of symbology "waviness". A narrow beamlet is traced from a pilot eye position backwards through the HUD optics until it hits the light source. Due to the small beamlet size, slope error of the aspheric surface acts primarily as an overall tilt/wedge that deviates the beam and causes it to shift. The slope error is acceptable when this shift is not resolved by a pilot eye. The beamlet is scanned over entire eyebox and field of view and the slope error tolerance is established for several zones in the aspheric surface clear aperture. The procedure is then repeated for each aspheric surface.

  6. LensClean revisited

    Wucknitz, O


    We discuss the LensClean algorithm which for a given gravitational lens model fits a source brightness distribution to interferometric radio data in a similar way as standard Clean does in the unlensed case. The lens model parameters can then be varied in order to minimize the residuals and determine the best model for the lens mass distribution. Our variant of this method is improved in order to be useful and stable even for high dynamic range systems with nearly degenerated lens model parameters. Our test case B0218+357 is dominated by two bright images but the information needed to constrain the unknown parameters is provided only by the relatively smooth and weak Einstein ring. The new variant of LensClean is able to fit lens models even in this difficult case. In order to allow the use of general mass models with LensClean, we develop the new method LenTil which inverts the lens equation much more reliably than any other method. This high reliability is essential for the use as part of LensClean. Finally...

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

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


    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. Comparison of Optical Performance in Eyes Implanted With Aspheric Foldable, Spherical Foldable, and Rigid PMMA IOLs

    van Gaalen, Kim W.; Jansonius, Nomdo M.; Koopmans, Steven A.; Kooijman, Aart C.


    PURPOSE: To compare the optical performance of rigid spherical polymethylmethacrylate (PMMA), foldable spherical, and foldable aspheric intraocular lenses (IOLs). METHODS: Measurements were obtained monocularly from pseudophakic patients with a PMMA IOL (Ophtec PC265y or Rayner 105U), spherical Acry

  9. Problems on design of computer-generated holograms for testing aspheric surfaces: principle and calculation

    Zhishan Gao; Meimei Kong; Rihong Zhu; Lei Chen


    Interferometric optical testing using computer-generated hologram (CGH) has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at center, for the sake of insuring lowisk of substrate figure error and feasibility of fabrication. On the basis of classic optics, a set of equations for calculating the phase function of CGH are obtained. These equations lead us to find the dependence of the aperture and spatial frequency on the axial diszance from the tested aspheric surface for the CGH. We also simulatethe ptical path difference error of the CGH relative to the accuracy of controlling laser spot during fabrication. Meanwhile, we discuss the constraints used to avoid zero slope of phase except at center and give a design result of the CGH for the tested aspheric surface. The results ensure the feasibility of designing a useful CGH to test aspheric urface fundamentally.

  10. Lens designs by ray tracing analyses for high-performance reflection optical modules

    Three kinds of novel optical modules are designed for high-efficiency light concentration. Each optical module consists of three components, namely a reflector, a second optical element (SOE) with a different parabolic profile and a concentrating lens. A concentrating lens with various profile designs is installed at the open end of the reflector to improve the uniformity of ray irradiances collected at the solar cell chip. An effective process for finding the optimum design for the geometries of these optical modules is presented to obtain good uniformity in ray irradiance distribution and high optical performance. The results of ray tracing simulations indicate that the optimum design is achieved based on the principle or the compromise of having the lowest value of the highest peak of ray irradiances and the highest optical performance. The optical module designed without a concentrating lens has a relatively high peak at the center of the circular irradiance distribution. The use of a Fresnel lens can impede the high peak effectively and achieve very good optical performance. Modules with spherical and aspherical concentrating lenses have irradiance peaks that are much higher than that of the Fresnel lens although their performance is negligibly higher than that of the Fresnel lens

  11. Hyper-hemispheric lens distortion model for 3D-imaging SPAD-array-based applications

    Pernechele, Claudio; Villa, Federica A.


    Panoramic omnidirectional lenses have the typical draw-back effect to obscure the frontal view, producing the classic "donut-shape" image in the focal plane. We realized a panoramic lens in which the frontal field is make available to be imaged in the focal plane together with the panoramic field, producing a FoV of 360° in azimuth and 270° in elevation; it have then the capabilities of a fish eye plus those of a panoramic lens: we call it hyper-hemispheric lens. We built and test an all-spherical hyper-hemispheric lens. The all-spherical configuration suffer for the typical issues of all ultra wide angle lenses: there is a large distortion at high view angles. The fundamental origin of the optical problems resides on the fact that chief rays angles on the object side are not preserved passing through the optics preceding the aperture stop (fore-optics). This effect produce an image distortion on the focal plane, with the focal length changing along the elevation angles. Moreover, the entrance pupil is shifting at large angle, where the paraxial approximation is not more valid, and tracing the rays appropriately require some effort to the optical designer. It has to be noted here as the distortion is not a source-point-aberrations: it is present also in well corrected optical lenses. Image distortion may be partially corrected using aspheric surface. We describe here how we correct it for our original hyper-hemispheric lens by designing an aspheric surface within the optical train and optimized for a Single Photon Avalanche Diode (SPAD) array-based imaging applications.

  12. Profile measurement of aspheric surfaces using scanning deflectometry and rotating autocollimator with wide measuring range

    High-accuracy aspherical mirrors and lenses with large dimensions are widely used in large telescopes and other industry fields. However, the measurement methods for large aspherical optical surfaces are not well established. Scanning deflectometry is used for measuring optical signals near flat surfaces with uncertainties on subnanometer scales. A critical issue regarding scanning deflectometry is that high-accuracy autocollimators (AC) have narrow angular measuring ranges and are not suitable for measuring surfaces with large slopes and angular changes. The goal of our study is to measure the profile of large aspherical optical surfaces with an accuracy of approximately 10 nm. We have proposed a new method to measure optical surfaces with large aspherical dimensions and large angular changes by using a scanning deflectometry method. A rotating AC was used to increase the allowable measuring range. Error analysis showed that the rotating AC reduces the accuracy of the measurements. In this study, we developed a new AC with complementary metal-oxide semiconductor (CMOS) as a light-receiving element (CMOS-type AC). The CMOS-type AC can measure wider ranges of angular changes, with a maximum range of 21 500 µrad (4500 arcsec) and a stability (standard deviation) of 0.1 µrad (0.02 arcsec). We conducted an experiment to verify the effectivity of the wide measuring range AC by the measurement of a spherical mirror with a curvature radius of 500 mm. Furthermore, we conducted an experiment to measure an aspherical optical surface (an off-axis parabolic mirror) and found an angular change of 0.07 rad (4 arcdegrees). The repeatability (average standard deviation) for ten measurements of the off-axis parabolic mirror was less than 4 nm. (paper)

  13. Len Yi Part 2

    Bsod nams rgyal mtshan


    INTRODUCTION: Sonan Jetsun (Bsod nams rgyal mtshan) filmed this material 12-22 January 2008 in Len yi (Lianyi) Village, Sgong po (Gongbo) Township, Sde rong (Derong) County, Dkar mdzes (Ganzi) Tibetan Autonomous Prefecture, Si khron (Sichuan) Province, PR China. The film features the Tibetan New Year, Bkra shis Temple, and ordinary people's lives in Len yi Village. Sonan Jetsun also edited the material and plans to give it to Len yi villagers on DVD/ VCD. LOCATION: Lianyi Village is 200 k...

  14. Flattop mode shaping of a vertical cavity surface emitting laser using an external-cavity aspheric mirror.

    Yang, Zhaohui; Leger, James


    Both square-shaped and circular-shaped flattop modes were experimentally demonstrated in extended-cavity broad-area VCSELs using aspheric feedback mirrors. These refractive aspheric mirrors were fabricated by electron-beam lithography on curved substrates. Excellent single-mode operation and improved power extraction efficiency were observed. The three-mirror structure of the VCSEL and the state-of-the-art fabrication of the aspheric mirror contribute to the superior VCSEL performance. The modal loss analysis using a rigid three-mirror-cavity simulation method is discussed. PMID:19484117

  15. Lens auto-centering

    Lamontagne, Frédéric; Desnoyers, Nichola; Doucet, Michel; Côté, Patrice; Gauvin, Jonny; Anctil, Geneviève; Tremblay, Mathieu


    In a typical optical system, optical elements usually need to be precisely positioned and aligned to perform the correct optical function. This positioning and alignment involves securing the optical element in a holder or mount. Proper centering of an optical element with respect to the holder is a delicate operation that generally requires tight manufacturing tolerances or active alignment, resulting in costly optical assemblies. To optimize optical performance and minimize manufacturing cost, there is a need for a lens mounting method that could relax manufacturing tolerance, reduce assembly time and provide high centering accuracy. This paper presents a patent pending lens mounting method developed at INO that can be compared to the drop-in technique for its simplicity while providing the level of accuracy close to that achievable with techniques using a centering machine (usually innovative auto-centering method is based on the use of geometrical relationship between the lens diameter, the lens radius of curvature and the thread angle of the retaining ring. The autocentering principle and centering test results performed on real optical assemblies are presented. In addition to the low assembly time, high centering accuracy, and environmental robustness, the INO auto-centering method has the advantage of relaxing lens and barrel bore diameter tolerances as well as lens wedge tolerances. The use of this novel lens mounting method significantly reduces manufacturing and assembly costs for high performance optical systems. Large volume productions would especially benefit from this advancement in precision lens mounting, potentially providing a drastic cost reduction.

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

    Meyer B


    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

  17. Blu-ray disk lens as the objective of a miniaturized two-photon fluorescence microscope.

    Chung, Hsiang-Yu; Kuo, Wei-Cheng; Cheng, Yu-Hsiang; Yu, Che-Hang; Chia, Shih-Hsuan; Lin, Cheng-Yung; Chen, Jie-Shin; Tsai, Huai-Jen; Fedotov, Andrey B; Ivanov, Anatoly A; Zheltikov, Aleksei M; Sun, Chi-Kuang


    In this paper, we examine the performance of a Blu-ray disk (BD) aspheric lens as the objective of a miniaturized scanning nonlinear optical microscope. By combining a single 2D micro-electro mechanical system (MEMS) mirror as the scanner and with different tube lens pairs, the field of view (FOV) of the studied microscope varies from 59 μm × 93 μm up to 178 μm × 280 μm, while the corresponding lateral resolution varies from 0.6 μm to 2 μm for two-photon fluorescence (2PF) signals. With a 34/s video frame rate, in vivo dynamic observation of zebrafish heartbeat through 2PF of the excited green fluorescence protein (GFP) is demonstrated. PMID:24514733

  18. Non-isothermal molding technology research of ultra-precision glass lens

    Zang, Hongbin; Yu, Jiaxin; Zhou, Yingyue; Tao, Bo


    This paper aims to research a unique non-isothermal molding technology (NGMP) which is an attractive and creative manufacturing method of fabricating ultra-precision and high-quality glass components. It has numerous advantages such as high efficiency, low cost and being mass production of glass lenses in industry. This technology is an ultra precision manufacturing process and suitable for multi-scale precision glass lens, lens array and glass micro-structure. This technology overcomes the disadvantages of traditional grinding and polishing technology such as long time production cycle, profligacy of raw materials, single-piece production and difficulty to produce an aspherical lens or arrays. The characteristics of NGMP are studied by comparing with the traditional IGMP. Residual stresses inside the glass lenses are also studied by numerical simulation. Based on the experiments and simulations results, a new compression molding process is proposed. Once the glass lens is fabricated by compression molding, an annealing process can be used to reduce the residual stresses in the glass lens.

  19. Use of the Humphrey Lens Analyzer for off-axis measurements of spectacle lenses.

    Atchison, D A; Kris, M; Sheedy, J E; Bailey, I L


    Automated focimeters can be used to make quick, precise measurements of off-axis power and prismatic effects corresponding to an eye rotating behind a spectacle lens. An automated focimeter, the Humphrey Lens Analyzer, was assessed in this regard. The Humphrey Lens Analyzer can be used to give a valid measure of off-axis power of lenses with low power, but not of lenses with moderate to higher power (greater than 3 D). For 3 D spherical lenses discrepancies of the order of 0.1 D occur at 30 degrees rotation, and 6 D spheres give discrepancies of 0.5 D at the same rotation. Small discrepancies were found for measurements of prism. The Humphrey Lens Analyzer was also used in a mode where the lens being tested is rotated about the center of curvature of its back surface. This is the mode often used to assess aberrations and prism of progressive-addition lenses. In this mode, the instrument provides reasonable accuracy in estimating off-axis power corresponding to eye rotation for lenses with low power, but not for lenses with moderate to higher power (greater than 3 D). However, it provides accurate values of the variation in off-axis surface power for low powered lenses with aspheric front surfaces. There were considerable systematic errors associated with the measurement of prism. A simple raytracing method was developed to predict the results of measurements with the Humphrey Lens Analyzer. Predictions of off-axis power were good when lenses were rotated about a position corresponding to the center-of-rotation of an eye, but were poorer when lenses were rotated about the center of curvature of their back surfaces. Predictions of primatic efforts were good in both situations. A method by which the Humphrey Lens Analyzer should provide an accurate measurement of off-axis powers corresponding to eye rotation behind a spectacle lens is described, but has not been tested. PMID:2052286

  20. Non-Radial Instabilities and Progenitor Asphericities in Core-Collapse Supernovae

    Mueller, B


    Since core-collapse supernova simulations still struggle to produce robust neutrino-driven explosions in 3D, it has been proposed that asphericities caused by convection in the progenitor might facilitate shock revival by boosting the activity of non-radial hydrodynamic instabilities in the post-shock region. We investigate this scenario in depth using 42 relativistic 2D simulations with multi-group neutrino transport to examine the effects of velocity and density perturbations in the progenitor for different perturbation geometries that obey fundamental physical constraints (like the anelastic condition). As a framework for analysing our results, we introduce semi-empirical scaling laws relating neutrino heating, average turbulent velocities in the gain region, and the shock deformation in the saturation limit of non-radial instabilities. The squared turbulent Mach number, , reflects the violence of aspherical motions in the gain layer, and explosive runaway occurs for ~0.3, corresponding to a reduction of t...

  1. Generation of Aspherical Optical Lenses via Arrested Spreading and Pinching of a Cross-Linkable Liquid.

    Roy, Abhijit Chandra; Yadav, Mridul; Arul, Edward Peter; Khanna, Anubhav; Ghatak, Animangsu


    Aspherical optical lenses with spatially varying curvature are desired for capturing high quality, aberration free images in numerous optical applications. Conventionally such lenses are prepared by multistep top-down processes which are expensive, time-consuming, and prone to high failure rate. In this context, an alternate method is presented here based on arrested spreading of a sessile drop of a transparent, cross-linkable polymeric liquid on a solid substrate heated to an elevated temperature. Whereas surface tension driven flow tends to render it spherical, rapid cross-linking arrests such flow so that nonequilibrium aspherical shapes are attained. It is possible to tune also the initial state of the drop via delayed pinching of a liquid cylinder which precedes its release on the substrate. This method has led to the generation of a wide variety of optical lenses, ranging from spherical plano convex to superspherical solid immersion to exotic lenses not achieved via conventional methods. PMID:27200461

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

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


    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. PMID:26368782

  3. Use of Virtual Medium in Designing of the CGH Wave Front Generator for Aspheric Testing

    KANG Guo-guo; XIE Jing-hui; LIU Yi


    Design method and procedures of computer-generated hologram (CGH) used for aspheric test are introduced in detail.For CGH phase calculation,virtual medium which has zero refractive index at given wavelength is used to model ideal aspheric wavefront.Reflective Fresnel zones located in a ring area concentric to the CGH structure is designed to reduce or eliminate alignment errors.Substrate figure error,pattern distortion,etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained to guide the tolerance distribution during CGH fabricating.A design example is given and the uncertainty of measurement achieves λ/20.


    GUO Yinbiao; WEI Lizhen


    In order to improve machining accuracy and efficiency, a software-controlled system of ultra-precision machining for axisymmetric aspheric mirror, using techniques of error compensation,remote transmission and modularization, is designed based on industrial PC, Windows 2000 work platform and Visual Basic 6.0. By experiments, this system realizes functions of ultra-precision machining, machining error compensation, remote data transmission and automatic data transformation among first machining, compensation machining and accuracy measurement. The actual application shows that error compensation improves machining accuracy, remote transmission improves machining efficiency while modularization avoids repeated work and improves design efficiency. Therefore, the system has met ultra-precision machining need for aspheric mirror.

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

    José Américo Bonatti


    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

  6. Comparisons of amplitude of pseudoaccommodation with aspheric yellow, spheric yellow, and spheric clear monofocal intraocular lenses

    Nishi T.; Taketani F; Ueda T; Ogata N.


    Tomo Nishi, Futoshi Taketani, Tetsuo Ueda, Nahoko Ogata Department of Ophthalmology, Nara Medical University, Kashihara City, Nara, Japan Purpose: To determine the amplitude of pseudoaccommodation and higher-order aberrations with three types of implanted monofocal intraocular lenses (IOLs): aspheric yellow (IQ); spheric yellow (NT); and spheric clear (AT). Setting: Department of Ophthalmology, Nara Medical University, Nara, Japan. Methods: We studied 60 patients who underwent small incision...

  7. Sensitivity of off-axis performance of aspheric spectacle lenses to tilt and decentration.

    Atchison, D A; Tame, S A


    Apparatus was modified to measure, and theoretical raytracing was used to predict, off-axis powers of spectacle lenses in the presence of tilt or decentration. In response to poor fitting in the form of tilt or decentration, lenses with aspheric front surfaces were found to have greater off-axis power errors than best-form lenses with spherical surfaces. This is attributable to the aspheric lenses having flatter surfaces than the spherical lenses. The errors are up to twice those occurring for the spherical lenses, and can be quite high, e.g. 0.9 D astigmatism for +6D power with 10 degrees tilt in 20 degrees upgaze. Negative lenses are more sensitive to poor fitting than are positive lenses of the same power. The errors for straight ahead vision associated with tilt are approximately proportional to the square of the angle of tilt, and the errors for straight ahead vision associated with decentration are approximately proportional to the square of decentration. It is most important that aspheric lenses be correctly fitted, which means that each 2 degrees of pantascopic tilt should be accompanied by approximately 1 mm decentration. PMID:8278198

  8. Reflections From a Fresnel Lens

    Keeports, David


    Reflection of light by a convex Fresnel lens gives rise to two distinct images. A highly convex inverted real reflective image forms on the object side of the lens, while an upright virtual reflective image forms on the opposite side of the lens. I describe here a set of laser experiments performed upon a Fresnel lens. These experiments provide…

  9. Internet based post-graduate course in spectacle lens design

    Jalie, Mo


    The complexity of spectacle lenses has increased enormously over the last three decades. The advent of aspheric lenses for the normal power range and the, now commonplace, progressive lenses for the correction of presbyopia, are just two examples of 21st Century technology. Freeform surfaces are now employed to personalize lenses to wearer's needs and these may be both progressive and atoroidal in nature. At the same time, optometry has taken a sideways step from optics and physics into a more general primary health care profession with an ever-increasing amount of biological and medical content added to an already brimming curriculum, hence the need for persons without optometry training to undertake the study of spectacle lenses. Some years ago a post-graduate course was designed for opticians who had a good grasp of mathematics and the ability to pay close attention to detail in the lengthy trigonometric ray-tracing techniques employed in lens design calculations. The year-long course, is undertaken by distance learning, and has been undertaken via the internet by students from many countries around the world. Final assessment is by means of examination held by the Association of British Dispensing Opticians and takes the form of two three-hour papers, Paper One consisting of the determination of the aberrations of a spectacle lens by accurate trigonometric ray tracing and the second, a general paper on the optics of ophthalmic lenses. It leads to the professional qualification, ABDO (Hons) SLD.

  10. Contact Lens Risks

    ... Health and Consumer Devices Consumer Products Contact Lenses Contact Lens Risks Share Tweet Linkedin Pin it More ... redness blurred vision swelling pain Serious Hazards of Contact Lenses Symptoms of eye irritation can indicate a ...

  11. Colored Contact Lens Dangers

    Full Text Available ... Sep 10, 2015 Contact Lens Horror Stories: Poor Care Can Lead to Blindness Sep 09, 2015 How to Correct High Myopia Feb 27, 2015 More Eye Health News Pet Fish Fitted with Fake Eye in ...

  12. Colored Contact Lens Dangers

    Full Text Available ... be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. ...

  13. Colored Contact Lens Dangers

    Full Text Available ... lens because they can be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, ... placed on the eye can lower internal eye pressure by about 20 percent for half a year. ...

  14. Colored Contact Lens Dangers

    Full Text Available ... had not been properly fitted by an eye care professional, the lenses stuck to my eye like ... lenses do not require the same level of care or consideration as a standard contact lens because ...

  15. Colored Contact Lens Dangers

    Full Text Available ... same level of care or consideration as a standard contact lens because they can be purchased over- ... lifestyle choices can directly affect your eyes. The best way to take care of your eyes during ...

  16. Colored Contact Lens Dangers

    Full Text Available ... lenses do not require the same level of care or consideration as a standard contact lens because they can be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ...

  17. Terahertz Artificial Dielectric Lens

    Mendis, Rajind; Nagai, Masaya; Wang, Yiqiu; Karl, Nicholas; Mittleman, Daniel M.


    We have designed, fabricated, and experimentally characterized a lens for the THz regime based on artificial dielectrics. These are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. For example, the well-known dielectric property, the refractive index, which usually has a value greater than unity, can have a value less than unity in an artificial dielectric. For our lens, the artificial-dielectric medium is made up of a parallel stack of 100 μm thick metal plates that form an array of parallel-plate waveguides. The convergent lens has a plano-concave geometry, in contrast to conventional dielectric lenses. Our results demonstrate that this lens is capable of focusing a 2 cm diameter beam to a spot size of 4 mm, at the design frequency of 0.17 THz. The results further demonstrate that the overall power transmission of the lens can be better than certain conventional dielectric lenses commonly used in the THz regime. Intriguingly, we also observe that under certain conditions, the lens boundary demarcated by the discontinuous plate edges actually resembles a smooth continuous surface. These results highlight the importance of this artificial-dielectric technology for the development of future THz-wave devices.

  18. Minimum lens complexity design approach for a free-space macro-optical multichip global interconnection module

    Milojkovic, Predrag; Christensen, Marc P.; Haney, Michael W.


    The FAST-Net (Free-space Accelerator for Switching Terabit Networks) concept uses an array of wide field-of-view imaging lenses to realize a high-density shuffle interconnect across an array of smart-pixel integrated circuits. This paper presents a design approach for these lenses that achieves the minimum complexity required to meet the demands of the FAST-Net concept's off-axis multi-chip environment. Generalized eikonals for arbitrary surfaces were examined to determine the performance bounds for the FAST-Net optical system. Then an analysis provided an estimate of 6 for the number of spherical surfaces needed to achieve good optical resolution and distortion performance across an array of 10-micron diameter VCSEL sources that are imaged onto a array of 50-micron wide detectors. A ray trace simulation confirmed this number. Subsequent analysis evaluated the achievable efficient of replacing spherical surfaces with aspherical ones. By exploiting the mismatch between the low numerical aperture VCSELs and relatively higher numerical aperture interconnection optics, it was found that 3 aspherical surfaces could replace 6 spherical surfaces in the FAST-Net system for the specified performance criteria. A lens design that utilizes 3 aspherical surfaces and achieves necessary registration and resolution of the FAST-Net system was determined. The results provide a general framework for the design of wide field-of-view free space interconnection systems that incorporate high-density VCSEL arrays.

  19. Multi-aspheric description of the myopic cornea after different refractive treatments and its correlation with corneal higher order aberrations

    Queirós, António; Villa-Collar, César; Jorge, Jorge; Gutiérrez, Ángel Ramón; González-Méijome, José Manuel


    Background To analyse the asphericity of the anterior corneal surface (ACS) for different diameters, and correlate those values with corneal higher order aberrations (cHOA) before and after myopic treatments with corneal refractive therapy (CRT) for orthokeratology and customized (CL) and standard laser (SL) assisted in situ keratomileusis (LASIK). Setting Clínica Oftalmológica NovoVisión, Madrid, Spain. Methods The right eyes of 81 patients (27 in each treatment group), with a mean age of 29.94 ± 7.5 years, were analysed. Corneal videokeratographic data were used to obtain corneal asphericity (Q) for different corneal diameters from 3 to 8 mm and cHOA root mean square (RMS) obtained from Zernike polynomials for a pupil diameter of 6 mm. Results There were statistically significant differences in asphericity values calculated at different corneal diameters for different refractive treatments and their changes. The difference between asphericity at 3 and 8 mm reference diameters showed statistically significant correlations with spherical-like cHOA that was also significantly increased after all procedures. Conclusions The shift in corneal asphericity and the differences among different treatment techniques are more evident for the smaller reference diameters. These differences can be much reduced or even masked for a peripheral reference point at 4 mm from centre, which is used by some corneal topographers.

  20. Challenges in holographic measurement of aspheric and freeform optical components shape

    Lédl, Vít; Psota, Pavel; Vojtíšek, Petr; Doleček, Roman; Mokrý, Pavel; Dlask, Martin

    Vol. 9508. Bellingham: SPIE-INT SOC OPTICAL ENGINEERING, 2015 - (Hrabovsky, M.; Sheridan, J.; Fimia, A.), 95080M-95080M. (SPIE). ISBN 978-1-62841-629-9. ISSN 0277-786X. [Conference on Holography - Advances and Modern Trends IV. Prague (CZ), 15.04.2015-16.04.2015] R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Holographic contouring * Multidirection illumination * Dualwavelength * Aspheric * Freeform * Polished Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  1. Super-polishing of Zerodur aspheres by means of conventional polishing technology

    Polák, Jaroslav; Klepetková, Eva; Pošmourný, Josef; Šulc, Miroslav; Procháska, František; Tomka, David; Matoušek, Ondřej; Poláková, Ivana; Šubert, Eduard

    Vol. 9442. Bellingham : SPIE-INT SOC OPTICAL ENGINEERING, 2015 - (Kovačičinová, J.; Vít, T.), s. 944212-944212 ISBN 978-1-62841-557-5. ISSN 0277-786X. - (SPIE). [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : super-polishing * smoothing * roughness reduction * bowl-feed polishing * aspheric polishing Subject RIV: JP - Industrial Processing

  2. 高次非球面的工艺技术研究%Manufacturing technology for high order aspheric surface

    袁吕军; 陈韬


    Since high order aspheric surface finds significant applications in optical system, a rapid and effective manufacturing technology is required to meet the demand. Software was developed with VC6. 0 for aspheric calculation to help fabrication, and a new compensation test was proposed for high order aspheric surface. Taking a high order aspheric collector with the diameter of 244mm as example, a manufacturing technology was developed and related investigations were conducted. Based on milling process and aspheric surface characteristics, several new grinding methods were proposed and related mathematical models were built. In order to process high order aspheric surface efficiently, computerized numerical control (CNC) milling direct shaping method was tested to reduce the complexity of subsequent processes, and numerical controlled small tool was combined with full aperture craft in polishing process to make aspheric surface smoother. Experimental results demonstrate the high order aspheric manufacturing technology is efficient, low cost and precise.%高次非球面在光学系统应用中意义重大,但是一直以来缺乏一套快速、有效的工艺方法.利用VC6.0编制了一款面型计算软件以辅助加工,并提出了一种新的高次非球面补偿检验方法.针对一块巡天光谱仪中口径φ244 mm的一面平面另一面为高次非球面的改正镜开展工艺方法的设计与研究,从铣磨成形开始,根据高次非球面的特点提出了几种新型磨削工艺,建立相应的数学模型.由于高次非球面的特殊性,试验了数控铣磨直接成型法,很大程度上降低后继工艺难度,在细磨和抛光阶段采用数控小工具和整工具研磨相结合,能够很好地克服面型不平滑等技术难题.总结出了一套高效率、低成本、高精度的高次非球面工艺方法.

  3. Luneburg lens in silicon photonics

    Di Falco, Andrea; Kehr, Susanne C; Leonhardt, Ulf


    The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms. (C) 2011 Optical Society of America

  4. Frequency selective lens antenna

    Thornton, J.; Haines, P.


    A variant of the hemispherical microwave lens antenna is reported where the ground plane region is modified through use of a frequency selective surface. This allows discrimination of frequencies by two closely spaced primary feeds. A scale model is reported operating at 12 and 30 GHz.

  5. Design of Ultra-Precision CNC Grinding Machine and Its Application in Machining Large Aspheric Mirrors

    Bin Li; Huiying Zhao; Jianpu Xi; Dongxu Ren


    Large aspheric mirrors are needed for the remote sensing and ground based telescope optical systems, these mirrors are made of hard and brittle materials which require ultra⁃precision grinding process to guarantee the high profile accuracy and machining efficiency. The ultra⁃precision aspheric CNC grinding machine (UAG900) is presented by this paper, as well as its grinding capability. The hydrostatic bearings of high accuracy and stiffness are adopted by the linear and rotary motions to guarantee the mirror accuracy, material removal rate and subsurface damage. Disk type grinding wheel with arc edge is used. The material removal rate can be up to 360 mm3/min to guarantee the machining efficiency during rough grinding using D180 diamond grinding wheel while the fine grinding is performed using D15 grinding wheel. It indicates that the grinding wheel radius measuring error is proportional to the profile error induced by the grinding path. The grinding step size is better to be 0�01 mm for the reduction of the grinding movement accelerations and program length. The grinding path is planned and expressed based on the grinding mode according to the mirror shape. One 540 mm×450 mm×100 mm zerodur mirror is ground and re⁃ground using the measuring data acquired by the Leitz CMM. The final surface accuracy of P⁃V value is less than 5 μm after compensation grinding.

  6. Human lens colouration, age and cataract

    Full text: The human lens biosynthesises UV filter compounds which effectively remove light in the 300-400nm band. These chemicals are present either as an aid to visual acuity, or to filter out damaging UV radiation. The primate UV filters are 3-hydroxykynurenine analogues derived from the metabolism of tryptophan. We have recently demonstrated that these endogenous UV filters are not innocuous, but are in fact capable of binding to proteins, including the crystalline proteins which make up the bulk of the lens. Thus, over time, the levels of protein - bound UV filters increase and this results in the human lens becoming progressively more yellow as we age. This colouration affects our colour vision and it may also be responsible for the brown colour of lenses which is the hallmark of age-related nuclear cataract. An understanding of the intrinsic instability of the endogenous UV filters, combined with changes in the internal transport of these and other small molecular weight compounds including antioxidants, such as glutathione, is allowing us to gain an insight into the processes responsible for the development of age-related cataract: the major cause of world blindness

  7. 30-Lens interferometer for high-energy X-rays.

    Lyubomirskiy, Mikhail; Snigireva, Irina; Kohn, Victor; Kuznetsov, Sergey; Yunkin, Vyacheslav; Vaughan, Gavin; Snigirev, Anatoly


    A novel high-energy multi-lens interferometer consisting of 30 arrays of planar compound refractive lenses is reported. Under coherent illumination each lens array creates a diffraction-limited secondary source. Overlapping such coherent beams produces an interference pattern demonstrating strong longitudinal functional dependence. The proposed multi-lens interferometer was tested experimentally at the 100 m-long ID11 ESRF beamline in the X-ray energy range from 30 to 65 keV. The interference pattern generated by the interferometer was recorded at fundamental and fractional Talbot distances. An effective source size (FWHM) of the order of 15 µm was determined from the first Talbot image, proving the concept that the multi-lens interferometer can be used as a high-resolution tool for beam diagnostics. PMID:27577763

  8. Error compensation in computer generated hologram-based form testing of aspheres.

    Stuerwald, Stephan


    Computer-generated holograms (CGHs) are used relatively often to test aspheric surfaces in the case of medium and high lot sizes. Until now differently modified measurement setups for optical form testing interferometry have been presented, like subaperture stitching interferometry and scanning interferometry. In contrast, for testing low to medium lot sizes in research and development, a variety of other tactile and nontactile measurement methods have been developed. In the case of CGH-based interferometric form testing, measurement deviations in the region of several tens of nanometers typically occur. Deviations arise especially due to a nonperfect alignment of the asphere relative to the testing wavefront. Therefore, the null test is user- and adjustment-dependent, which results in insufficient repeatability and reproducibility of the form errors. When adjusting a CGH, an operator usually performs a minimization of the spatial frequency of the fringe pattern. An adjustment to the ideal position, however, often cannot be performed with sufficient precision by the operator as the position of minimum spatial fringe density is often not unique, which also depends on the asphere. Thus, the scientific and technical objectives of this paper comprise the development of a simulation-based approach to explain and quantify typical experimental errors due to misalignment of the specimen toward a CGH in an optical form testing measurement system. A further step is the programming of an iterative method to realize a virtual optimized realignment of the system on the basis of Zernike polynomial decomposition, which should allow for the calculation of the measured form for an ideal alignment and thus a careful subtraction of a typical alignment-based form error. To validate the simulation-based findings, a series of systematic experiments is performed with a recently developed hexapod positioning system in order to allow an exact and reproducible positioning of the optical CGH

  9. Functional modular contact lens

    Shum, Angela J.; Cowan, Melissa; Lähdesmäki, Ilkka; Lingley, Andrew; Otis, Brian; Parviz, Babak A.


    Tear fluid offers a potential route for non-invasive sensing of physiological parameters. Utilization of this potential depends on the ability to manufacture sensors that can be placed on the surface of the eye. A contact lens makes a natural platform for such sensors, but contact lens polymers present a challenge for sensor fabrication. This paper describes a microfabrication process for constructing sensors that can be integrated into the structure of a functional contact lens in the future. To demonstrate the capabilities of the process, an amperometric glucose sensor was fabricated on a polymer substrate. The sensor consists of platinum working and counter electrodes, as well as a region of indium-tin oxide (ITO) for glucose oxidase immobilization. An external silver-silver chloride electrode was used as the reference electrode during the characterization experiments. Sensor operation was validated by hydrogen peroxide measurements in the 10- 20 μM range and glucose measurements in the 0.125-20 mM range.

  10. Silicone oil-intraocular lens interaction: which lens to use?

    McLoone, E; Mahon, G; Archer, D.; Best, R


    AIM—To determine a suitable intraocular lens for implantation in patients at high risk of lens exposure to silicone oil in their lifetime.
METHODS—PMMA, AcrySof, AR40, AQUA-Sense, and Raysoft lenses were examined. Each lens was immersed for 5 minute intervals in balanced salt solution (BSS), in stained silicone oil, and again in BSS before being photographed in air and in BSS. Percentage silicone oil coverage of the lens optic was determined.
RESULTS—The mean percentage coating (MPC) for the ...

  11. Design, fabrication, and testing of micro-optical sensors containing multiple aspheres

    Rajic, S.; Egert, C.M.; Evans, B.M. III; Cunningham, J.P.; Marlar, T.A.


    The micro-sensor field is presently proliferating with designs and approaches. The authors have developed a micro-spectrometer for sensing application containing five precision surfaces, including two off-axis aspheres. The entire monolith is less than six cubic centimeters in volume. This particular design contains a bandwidth of about 1 micrometer which is centered at 980 nm. Once an appropriate starting substrate was produced, the entire system was diamond turned to maintain the required surface figure, inter-surface spacing, and surface tilts. Only three diamond turned fixtures were needed to produce the monolith. The results proved to be more than adequate for many sensing applications. Slightly altered designs could easily be produced containing different bandwidths and resolutions as needed by the customer. Due to the spectrum of interest and the fabrication method, PMMA was the material chosen for this sensor. Other designs configurations incorporating BK7 and sapphire are presently being studied.

  12. Aspherical nucleosynthesis in a core-collapse supernova with 25 M ☉ standard progenitor

    The problem of nucleosynthesis was studied within an aspherical supernova model. The explosive burning was computed in a star of 25 M ☉ 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.

  13. Crowded, cell-like environment induces shape changes in aspherical protein

    Cheung, Margaret


    How the crowded environment inside cells affects the structures of proteins with aspherical shapes is a vital question because many proteins and protein--protein complexes in vivo adopt anisotropic shapes. Here we address this question by combining computational and experimental studies of a football-shaped protein (i.e. Borrelia burgdorferi VlsE) under crowded, cell-like conditions. The results show that macromolecular crowding affects protein-folding dynamics as well as overall protein shape. In crowded milieus, distinct conformational changes in VlsE are accompanied by secondary structure alterations that lead to exposure of a hidden antigenic region. Our work demonstrates the malleability of ``native'' proteins and implies that crowding-induced shape changes may be important for protein function and malfunction in vivo.

  14. Aspherical surface profile fitting based on the relationship between polynomial and inner products

    Cheng, Xuemin; Yang, Yikang; Hao, Qun


    High-precision aspherical polynomial fitting is essential to image quality evaluation in optical design and optimization. However, conventional fitting methods cannot reach optimal fitting precision and may somehow induce numerical ill-conditioning, such as excessively high coefficients. For this reason, a projection from polynomial equations to vector space was here proposed such that polynomial solutions could be obtained based on matrix and vector operation, so avoiding the problem of excessive coefficients. The Newton-Raphson iteration method was used to search for optimal fitting of the spherical surface. The profile fitting test showed that the proposed approach was able to obtain results with high precision and small value, which solved the numerical ill-conditioning phenomenon effectively.

  15. Stray, swing and scatter: angular momentum evolution of orbits and streams in aspherical potentials

    Erkal, Denis; Belokurov, Vasily


    In aspherical potentials orbital planes continuously evolve. The gravitational torques impel the angular momentum vector to precess, that is to slowly stray around the symmetry axis, and nutate, i.e. swing up and down periodically in the perpendicular direction. This familiar orbital pole motion - if detected and measured - can reveal the shape of the underlying gravitational potential, the quantity only crudely gauged in the Galaxy so far. Here we demonstrate that the debris poles of stellar tidal streams show a very similar straying and swinging behavior, and give analytic expressions to link the amplitude and the frequency of the pole evolution to the flattening of the dark matter distribution. Most importantly, we explain how the differential orbital plane precession leads to the broadening of the stream and show that streams on polar orbits ought to scatter faster. We provide expressions for the stream width evolution as a function of the axisymmetric potential flattening and the angle from the symmetry ...

  16. The Optimal Gravitational Lens Telescope

    Surdej, J; Coleman, P; Dominik, M; Habraken, S; Hanot, C; Coroller, H Le; Mawet, D; Quintana, H; Sadibekova, T; Sluse, D; 10.1088/0004-6256/139/5/1935


    Given an observed gravitational lens mirage produced by a foreground deflector (cf. galaxy, quasar, cluster,...), it is possible via numerical lens inversion to retrieve the real source image, taking full advantage of the magnifying power of the cosmic lens. This has been achieved in the past for several remarkable gravitational lens systems. Instead, we propose here to invert an observed multiply imaged source directly at the telescope using an ad-hoc optical instrument which is described in the present paper. Compared to the previous method, this should allow one to detect fainter source features as well as to use such an optimal gravitational lens telescope to explore even fainter objects located behind and near the lens. Laboratory and numerical experiments illustrate this new approach.

  17. Advances in lens implant technology

    Kook, Daniel; Kampik, Anselm; Dexl, Alois K.; Zimmermann, Nicole; Glasser, Adrian; Baumeister, Martin; Kohnen, Thomas


    Cataract surgery is one of the oldest and the most frequent outpatient clinic operations in medicine performed worldwide. The clouded human crystalline lens is replaced by an artificial intraocular lens implanted into the capsular bag. During the last six decades, cataract surgery has undergone rapid development from a traumatic, manual surgical procedure with implantation of a simple lens to a minimally invasive intervention increasingly assisted by high technology and a broad variety of imp...

  18. Connexin hemichannels in the lens



    The normal function and survival of cells in the avascular lens is facilitated by intercellular communication through an extensive network of gap junctions formed predominantly by three connexins (Cx43, Cx46, and Cx50). In expression systems, these connexins can all induce hemi-channel currents, but other lens proteins (e.g., pannexin1) can also induce similar currents. Hemichannel currents have been detected in isolated lens fiber cells. These hemichannels may make significant contributio...

  19. Connexin hemichannels in the lens

    Beyer, Eric C.; Berthoud, Viviana M.


    The normal function and survival of cells in the avascular lens is facilitated by intercellular communication through an extensive network of gap junctions formed predominantly by three connexins (Cx43, Cx46, and Cx50). In expression systems, these connexins can all induce hemichannel currents, but other lens proteins (e.g., pannexin1) can also induce similar currents. Hemichannel currents have been detected in isolated lens fiber cells. These hemichannels may make significant contributions t...

  20. Dispersion-compensated fresnel lens

    Johnson, Kenneth C.


    A transmission grating is used to reduce chromatic aberration in a Fresnel lens, wherein the lens chromatic dispersion is offset and substantially canceled by the grating's diffraction-induced dispersion. The grating comprises a Fresnel-type pattern of microscopic facets molded directly into the lens surface. The facets would typically have a profile height of around 4.multidot.10.sup.-5 inch and a profile width of at least 10.sup.-3 inch. In its primary intended application, the invention would function to improve the optical performance of a Fresnel lens used to concentrate direct sunlight.

  1. Automated synthesis of both the topology and numerical parameters for seven patented optical lens systems using genetic programming

    Jones, Lee W.; Al-Sakran, Sameer H.; Koza, John R.


    This paper describes how genetic programming was used as an automated invention machine to synthesize both the topology and numerical parameters for seven previously patented optical lens systems, including one aspherical system and one issued in the 21st-century. Two of the evolved optical lens systems infringe the claims of the patents and the others are novel solutions that satisfy the design goals stated in the patent. The automatic synthesis was done "from scratch"--that is, without starting from a pre-existing good design and without pre-specifying the number of lenses, the topological layout of the lenses, or the numerical parameters of the lenses. Genetic programming is a form of evolutionary computation used to automatically solve problems. It starts from a high-level statement of what needs to be done and progressively breeds a population of candidate individuals over many generations using the principle of Darwinian natural selection and genetic recombination. The paper describes how genetic programming created eyepieces that duplicated the functionality of seven previously patented lens systems. The seven designs were created in a substantially similar and routine way, suggesting that the use of genetic programming in the automated design of both the topology and numerical parameters for optical lens systems may have widespread utility.

  2. Development of lens sutures.

    Kuszak, Jer R; Zoltoski, Rebecca K; Tiedemann, Clifford E


    Cylindrical map projections (CMPs) have been used for centuries as an effective means of plotting the features of a 3D spheroidal surfaces (e.g. the earth) on a 2D rectangular map. We have used CMPs to plot primate fiber cell organization from selected growth shells as a function of growth, development and aging. Lens structural parameters and features were derived from slit-lamp, light and transmission and scanning electron micrographs. This information was then used to create CMPs of lenses that were then correlated with azimuthal map projections (AMPs; projections that are radially symmetric around a central point [the poles]) to reveal different suture patterns during distinct time periods. In this manner, both lens fiber and suture branch locations are defined by degrees of longitude and latitude. CMPs and AMPs confirm that throughout defined periods of development, growth and ageing, increasingly complex suture patterns are formed by the precise ordering of straight and opposite end curvature fibers. However, the manner in which additional suture branches are formed anteriorly and posteriorly is not identical. Anteriorly, new branches are added between extant branches. Posteriorly, pairs of new branches are formed that progressively overlay extant branches. The advantage of using CMPs is that the shape and organization of every fiber in a growth shell can be observed in a single image. Thus, the use of CMPs to plot primate fiber cell organization has revealed more complex aspects of fiber formation that may explain, at least in part, changes in lens optical quality as a function of age and pathology. In addition, more accurate measurements of fiber length will be possible by incorporating the latitudinal and longitudinal locations of fibers. PMID:15558480

  3. Lens of Eye Dosimetry

    Mallett, Michael Wesley [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    An analysis of LANL occupational dose measurements was made with respect to lens of eye dose (LOE), in particular, for plutonium workers. Table 1 shows the reported LOE as a ratio of the “deep” (photon only) and “deep+neutron” dose for routine monitored workers at LANL for the past ten years. The data compares the mean and range of these values for plutonium workers* and non-routine plutonium workers. All doses were reported based on measurements with the LANL Model 8823 TLD.

  4. Diffractive Alvarez lens

    A diffractive Alvarez lens is demonstrated that consists of two separate phase plates, each having complementary 16-level surface-relief profiles that contain cubic phase delays. Translation of these two components in the plane of the phase plates is shown to produce a variable astigmatic focus. Both spherical and cylindrical phase profiles are demonstrated with good accuracy, and the discrete surface-relief features are shown to cause less than λ/10 wave-front aberration in the transmitted wave front over a 40 mmx80 mm region. (c) 2000 Optical Society of America

  5. Vitamin C–mediated Maillard Reaction in the Lens Probed in a Transgenic-mouse Model

    Fan, Xingjun; Monnier, Vincent M.


    Aging human lens crystallins are progressively modified by yellow glycation, oxidation, and cross-linked carbonyl compounds that have deleterious properties on protein structure and stability. In order to test the hypothesis that some of these compounds originate from oxidized vitamin C, we have overexpressed the human vitamin C transporter 2 (hSCVT2) in the mouse lens. We find that levels of ascorbic and dehydroascorbic acid are highly elevated compared to the wild type and that the lenses h...

  6. Two-photon excited fluorescence of the lens for the diagnosis of presbyopia

    Steiner, R.; Kessler, M.; Fugger, O.; Dolp, F.; Russ, D.


    Presbyopia is a wide spread phenomenon in elder people and is caused by the hardening of the lens in human eyes. Research is performed to make such lenses again more flexible by application of geometrically optimised cuts through the lens with a femtosecond-laser. Different protein agglomerations are responsible for the flexibility reduction of the lens. Two-photon excited fluorescence of the lens can be used as a diagnostic tool to localise such protein accumulations. In in-vitro experiments with human cataract lenses and also lenses of the Philly-mouse it could be demonstrated that with age the fluorescence increases as presbyopia proceeds. The distribution of the fluorescing compounds are not homogeneous but rather cloudy. Discrimination of the compounds by fluorescence lifetime measurements in relation of the depth in the lens is possible.

  7. The ultrahigh precision form measurement of small, steep-sided aspheric moulds, incorporating novel hardware and software developments; Technical Digest

    Mills, M. W.; Hutchinson, Matthew J.


    A variety of consumer applications, eg cellphone camera lenses, optical storage devices, digital cameras, etc, are driving the demand for small, high aspheric departure rotationally-symmetric moulded optics, manufactured both in polymer and glass materials. The mould tools for such components are manufactured by ultra-high precision techniques such as single point diamond turning and ultra-precision grinding, and must be accurate to mould.

  8. Shack-Fizeau interferometer and some methods to process their aspheric wavefront interferograms using a CCD detector

    Rivera, Mariano; Garcia, J.; Malacara, D.; Marroquin, Jose L.


    A Fizeau interferometer has been built to test aspherical and concave telescope mirrors. Results of one method used to evaluate the maximum number of fringes when the interferogram image is projected on a CCD device are mentioned. Some complementary techniques have been utilized to analyze interferograms using this kind of interferometer. A deterministic approach to the regularization term added by Marroquin and Rivera (1995) to the least-squares unwrapping technique is shown.

  9. Excimer laser micromachining of aspheric microlens arrays based on optimal contour mask design and laser dragging method.

    Chiu, Chi-Cheng; Lee, Yung-Chun


    This paper presents an improved excimer laser micromachining method for fabricating arrayed microstructures with a predesigned surface profile. The proposed method is developed from a conventional biaxial laser dragging method, but numerical analysis and optimal pattern design on the contour mask are introduced so that the machined surface profiles can be well controlled and matched to the designed profiles. To demonstrate the capability of this new approach, an array of aspheric microlenses that have analog surfaces for minimizing the focal spot sizes of the lenses is designed and fabricated. An array of 10×10 microlenses with an aperture size of 100 μm and a designed aspheric profile are obtained experimentally. The machined surface profiles are closely matched to their designed ones, with a profile deviation of less than 1 μm. Furthermore, the machined surfaces are smooth, with an average surface roughness of around 2 nm. Optical measurements on these machined aspheric microlenses show minimized focal spot sizes approaching their optical diffraction limits. PMID:22418468

  10. The Deep Lens Survey

    Wittman, D; Dell'Antonio, I P; Becker, A C; Margoniner, V E; Cohen, J; Norman, D; Loomba, D; Squires, G; Wilson, G; Stubbs, C; Hennawi, J F; Spergel, D N; Boeshaar, P C; Clocchiatti, A; Hamuy, M; Bernstein, G; González, A; Guhathakurta, R; Hu, W; Seljak, U; Zaritsky, D


    The Deep Lens Survey (DLS) is a deep BVRz' imaging survey of seven 2x2 degree fields, with all data to be made public. The primary scientific driver is weak gravitational lensing, but the survey is also designed to enable a wide array of other astrophysical investigations. A unique feature of this survey is the search for transient phenomena. We subtract multiple exposures of a field, detect differences, classify, and release transients on the Web within about an hour of observation. Here we summarize the scientific goals of the DLS, field and filter selection, observing techniques and current status, data reduction, data products and release, and transient detections. Finally, we discuss some lessons which might apply to future large surveys such as LSST.

  11. Investigation into photostability of soybean oils by thermal lens spectroscopy

    Savi, E. L.; Malacarne, L. C.; Baesso, M. L.; Pintro, P. T. M.; Croge, C.; Shen, J.; Astrath, N. G. C.


    Assessment of photochemical stability is essential for evaluating quality and the shelf life of vegetable oils, which are very important aspects of marketing and human health. Most of conventional methods used to investigate oxidative stability requires long time experimental procedures with high consumption of chemical inputs for the preparation or extraction of sample compounds. In this work we propose a time-resolved thermal lens method to analyze photostability of edible oils by quantitative measurement of photoreaction cross-section. An all-numerical routine is employed to solve a complex theoretical problem involving photochemical reaction, thermal lens effect, and mass diffusion during local laser excitation. The photostability of pure oil and oils with natural and synthetic antioxidants is investigated. The thermal lens results are compared with those obtained by conventional methods, and a complete set of physical properties of the samples is presented.

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

    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)


    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.

  13. A modified stitching algorithm for testing rotationally symmetric aspherical surfaces with annular sub-apertures

    Hou, Xi; Wu, Fan; Yang, Li; Wu, Shi-bin; Chen, Qiang


    Annular sub-aperture stitching technique has been developed for low cost and flexible testing rotationally symmetric aspherical surfaces, of which combining accurately the sub-aperture measurement data corrupted by misalignments into a complete surface figure is the key problem. An existed stitching algorithm of annular sub-apertures can convert sub-aperture Zernike coefficients into full-aperture Zernike coefficients, in which use of Zernike circle polynomials represents sub-aperture data over both circle and annular domain. Since Zernike circle polynomials are not orthogonal over annular dominion, the fitting results may give wrong results. In this paper, the Zernike polynomials and existed stitching algorithm have been reviewed, and a modified stitching algorithm with Zernike annular polynomials is provided. The performances of a modified algorithm on the reconstruction precision are studied by comparing with the algorithm existed. The results of computer simulation show that the sub-aperture data reduction with the modified algorithm is more accurate than that obtained with the existed algorithm based on Zernike circle polynomials, and the undergoing matrix manipulation is simpler.

  14. Stray, swing and scatter: angular momentum evolution of orbits and streams in aspherical potentials

    Erkal, Denis; Sanders, Jason L.; Belokurov, Vasily


    In aspherical potentials orbital planes continuously evolve. The gravitational torques impel the angular momentum vector to precess, that is to slowly stray around the symmetry axis, and nutate, i.e. swing up and down periodically in the perpendicular direction. This familiar orbital pole motion - if detected and measured - can reveal the shape of the underlying gravitational potential, the quantity only crudely gauged in the Galaxy so far. Here we demonstrate that the debris poles of stellar tidal streams show a very similar straying and swinging behaviour, and give analytic expressions to link the amplitude and the frequency of the pole evolution to the flattening of the dark matter distribution. While these results are derived for near-circular orbits, we show they are also valid for eccentric orbits. Most importantly, we explain how the differential orbital plane precession leads to the broadening of the stream and show that streams on polar orbits ought to scatter faster. We provide expressions for the stream width evolution as a function of the axisymmetric potential flattening and the angle from the symmetry plane and prove that our models are in good agreement with streams produced in N-body simulations. Interestingly, the same intuition applies to streams whose progenitors are on short- or long-axis loops in a triaxial potential. Finally, we present a compilation of the Galactic cold stream data, and discuss how the simple picture developed here, along with stream modelling, can be used to constrain the symmetry axes and flattening of the Milky Way.

  15. Error Correction of a Phase-Only Computer-Generated Hologram for an Aspheric Surface

    Zhang, H.; Yan, Y.; Zhou, H.; Qiao, Y. J.; Si, J.; Wang, D.


    When applying phase-only computer-generated hologram (CGH) as a standard model of optical measurement in computer-generated holography for aspheric surface testing, it has the advantage of simplifying optical path configuration and improving the diffraction efficiency of the incoming light. However, errors always exists during the encoding process of fabricating multiphase level CGHs and this kind of errors will be amplified level by level in the measurement. According to the analysis of the encoding error, the error of CGH increases linearly when its quantified period increases. For example, if the quantified period is 32, the maximum of encoding error is 16.46 which can lead wave-front aberration 0.085λ of a secondary parabolic surface with 512 x 512 sampling pixels. In this article, an optimization method based on deviation of minimum boundary value has been used to eliminate the encoding error of CGH. In the experiment, we use a liquid crystal spatial light modulator to generate CGHs and measure residuals of reconstructed wave-front of a secondary parabolic surface. The measurement results show that average decrease of the RMS values of the residuals is 0.07λ when their periods range from 3 to 6, which indicates the optimization method is effective.

  16. Improving the quantitative testing of fast aspherics surfaces with null screen using Dijkstra algorithm

    Moreno Oliva, Víctor Iván; Castañeda Mendoza, Álvaro; Campos García, Manuel; Díaz Uribe, Rufino


    The null screen is a geometric method that allows the testing of fast aspherical surfaces, this method measured the local slope at the surface and by numerical integration the shape of the surface is measured. The usual technique for the numerical evaluation of the surface is the trapezoidal rule, is well-known fact that the truncation error increases with the second power of the spacing between spots of the integration path. Those paths are constructed following spots reflected on the surface and starting in an initial select spot. To reduce the numerical errors in this work we propose the use of the Dijkstra algorithm.1 This algorithm can find the shortest path from one spot (or vertex) to another spot in a weighted connex graph. Using a modification of the algorithm it is possible to find the minimal path from one select spot to all others ones. This automates and simplifies the integration process in the test with null screens. In this work is shown the efficient proposed evaluating a previously surface with a traditional process.

  17. Photothermal Lens Aberration Effects in Two Laser Thermal Lens Spectrometry

    Bialkowski, Stephen E.


    A comparison of theories describing two laser photothermal lens signals is given. The aberrant nature of this lens is accounted for in a theory which treats the propagation of a monitor laser in terms of a phase shift in this laser beam wave front. The difference between theories are discussed in terms of the predicted signal strengths and temporal behavior. The aberrant theory results in smaller theoretical signal strengths and different functional relationships between signal and analyte le...

  18. Lens design based on lens form parameters using Gaussian brackets

    Yuan, Xiangyu; Cheng, Xuemin


    The optical power distribution and the symmetry of the lens components are two important attributes that decide the ultimate lens performance and characteristics. Lens form parameters W and S are the key criteria describing the two attributes mentioned above. Lens components with smaller W and S will have a good nature of aberration balance and perform well in providing good image quality. Applying the Gaussian brackets, the two lens form parameters and the Seidel Aberration Coefficients are reconstructed. An initial lens structure can be analytically described by simultaneous equations of Seidel Aberration Coefficients and third-order aberration theory. Adding the constraints of parameters W and S in the solving process, a solution with a proper image quality and aberration distribution is achieved. The optical properties and image quality of the system based on the parameters W and S are also analyzed in this article. In the method, the aberration distribution can be controlled to some extent in the beginning of design, so that we can reduce some workload of optimization later.

  19. 影响激光驱动器注入镜组特性的误差因素分析%AnaIysis of Error Factor Impacting on the Performance of Laser-driver Injection Compound Lens

    柏占伟; 谢志江; 袁晓东


    研究了惯性约束大功率激光聚变驱动器注入镜组特性影响因素,分析表明透镜的几何尺寸公差、透镜装配公差和镜组在线安装公差等因素对镜组焦距公差、焦斑分布、波像差方面的特性影响较大。针对影响镜组特性的主要因素,建立了镜组特性影响分析的相关数学模型,并基于MatIab和Zemax软件平台对模型进行模拟计算,结果表明数学模型可以保证镜组特性需要的制造、安装公差。%During the study Of aII kinds Of tOIerance infIuencing factOrs On the perfOrmance Of injectiOn cOmpOund Iens made Of high pOwer Iaser inertiaI cOnfinement fusiOn drive,anaIysis shOws that geOmetry dimensiOn tOIerance Of the Iens,Iens assembIy tOIerance and cOmpOund Iens have a significant effect On the perfOmance Of cOmpOund Iens fOcaI Iength tOIerance, fOcaI spOt pOsitiOn and wave aberratiOn. AccOrding tO the main infIuencing factOrs,reIated perfOrmance mathematicaI mOdeIs are set up. The mOdeIs are simuIated and the resuIts Of simuIatiOn are anaIyzed based On the sOftware pIatfOrm Of MatIab and Zemax. The manufacturing and instaIIatiOn tOIerance ensuring the perfOrmance are aIsO determined based On the simuIatiOn resuIts and tOIerance Of cOmpOund Iens.

  20. Adjustable hybrid diffractive/refractive achromatic lens

    Valley, Pouria; Savidis, Nickolaos; Schwiegerling, Jim; Dodge, Mohammad Reza; Peyman, Gholam; N. Peyghambarian


    We demonstrate a variable focal length achromatic lens that consists of a flat liquid crystal diffractive lens and a pressure-controlled fluidic refractive lens. The diffractive lens is composed of a flat binary Fresnel zone structure and a thin liquid crystal layer, producing high efficiency and millisecond switching times while applying a low ac voltage input. The focusing power of the diffractive lens is adjusted by electrically modifying the sub-zones and re-establishing phase wrapping po...

  1. Contact Lens Related Corneal Ulcer

    Loh, KY; P Agarwal


    A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. Th...

  2. Inverse Design of Electron Lens


    The inverae design of electron lens is reelized by two different methods in this paper. One isdamped leastsquare method and the other is the artificial neural network method. Their merits and defects are discussed accordingto our calculation results in the psper. In the condition of selecting the learning samples properly, the artificial neuralnetwork has obvious advantages in the inverse design of electron lens. It is an effective method to solve the inversedesign problem in the electron optic system.

  3. Trade-offs between lens complexity and real estate utilization in a free-space multichip global interconnection module

    Milojkovic, Predrag; Christensen, Marc P.; Haney, Michael W.


    The FAST-Net (Free-space Accelerator for Switching Terabit Networks) concept uses an array of wide-field-of-view imaging lenses to realize a high-density shuffle interconnect pattern across an array of smart-pixel integrated circuits. To simplify the optics we evaluated the efficiency gained in replacing spherical surfaces with aspherical surfaces by exploiting the large disparity between narrow vertical cavity surface emitting laser (VCSEL) beams and the wide field of view of the imaging optics. We then analyzed trade-offs between lens complexity and chip real estate utilization and determined that there exists an optimal numerical aperture for VCSELs that maximizes their area density. The results provide a general framework for the design of wide-field-of-view free-space interconnection systems that incorporate high-density VCSEL arrays.

  4. A course in lens design

    Velzel, Chris


    A Course in Lens Design is an instruction in the design of image-forming optical systems. It teaches how a satisfactory design can be obtained in a straightforward way. Theory is limited to a minimum, and used to support the practical design work. The book introduces geometrical optics, optical instruments and aberrations. It gives a description of the process of lens design and of the strategies used in this process. Half of its content is devoted to the design of sixteen types of lenses, described in detail from beginning to end. This book is different from most other books on lens design because it stresses the importance of the initial phases of the design process: (paraxial) lay-out and (thin-lens) pre-design. The argument for this change of accent is that in these phases much information can be obtained about the properties of the lens to be designed. This information can be used in later phases of the design. This makes A Course in Lens Design a useful self-study book, and a suitable basis for an intro...

  5. Gabor lens theory

    The principle of using the space charge of an electron cloud to focus ion beams was first proposed by Gabor. Electrons are to be confined radially by means of an axial magnetic field B/sub z/ and axially by means of externally applied electric fields E/sub z/. An ion beam of charge density n/sub i/ much less than n/sub e/, the electron charge density can then be focused by the radial electric field set up by the electron cloud. The case considered here is that of a hollow cylindrical conductor charged to a potential +V with grounded rings on either side to set up the axial E/sub z/ field. A solenoid wound around the central conductor supplies the B/sub z/ field. Theoretical calculations are carried out for n/sub e/ maximum as a function of B/sub z/ due to radial confinement and V due to axial confinement and the focal length of the Gabor Lens is calculated

  6. Model-based calibration of an interferometric setup with a diffractive zoom-lens

    Bielke, Alexander; Baer, Goran; Pruss, Christof; Osten, Wolfgang


    The fabrication of aspheres and freeform surfaces requires a high-precision shape measurement of these elements. In terms of accuracy, interferometric systems provide the best performance for specular surfaces. To test aspherical lenses, it is necessary to adapt or partially adapt the test wavefront to the surface under test. Recently, we have proposed an interferometric setup with a diffractive zoom-lens that includes two computer generated holograms for this purpose.1 Their surface phases are a combination of a cubic function for the adaption of aberrations and correction terms necessary to compensate substrate-induced errors. With this system based on Alvarez design a variable defocus and astigmatism controlled by a lateral shift of the second element is achieved. One of the main challenges is the calibration of the system. We use a black-box model2 recently introduced for a non-null test interferometer, the so called tilted wave interferometer3 (TWI). With it, the calibration data are calculated by solving an inverse problem. The system is divided in the two parts of illumination and imaging optics. By the solution of an inverse problem, we get a set of data, which describes separately the wavefronts of the illumination and imaging optics. The main difference to the TWI is the flexible diffractive element, which can be used in continuous positions. To combine the calibration data of a couple of positions with the exact placement, we designed alignment structures on the hologram. We will show the general functionality of this calibration and first simulation results.

  7. Investigation of error compensation in CGH-based form testing of aspheres

    Stuerwald, S.; Brill, N.; Schmitt, R.


    Interferometric form testing using computer generated holograms is one of the main full-field measurement techniques. Till now, various modified measurement setups for optical form testing interferometry have been presented. Currently, typical form deviations in the region of several tens of nanometers occur in case of the widely used computer generated hologram (CGH) based interferometric form testing. Deviations occur due to a non-perfect alignment of the computer generated hologram (CGH) relative to the transmission sphere (Fizeau objective) and also of the asphere relative to the testing wavefront. Thus, measurement results are user and setup dependent which results in an unsatisfactory reproducibility of the form errors. In case of aligning a CGH, this usually requires a minimization of the spatial frequency of the fringe pattern by an operator. Finding the ideal position however often cannot be performed with sufficient accuracy by the operator as the position of minimum spatial fringe density is usually not unique. Therefore, the scientific and technical objectives of this paper comprise the development of a simulation based approach to explain and quantify the experimental errors due to misalignment of the specimen towards a computer generated hologram in an optical form testing measurement system. A further step is the programming of an iterative method to realize a virtual optimised realignment of the system on the basis of Zernike polynomial decomposition which should allow the calculation of the measured form for an ideal alignment and thus the subtraction of the alignment based form error. Different analysis approaches are investigated with regard to the final accuracy and reproducibility. To validate the theoretical models a series of systematic experiments is performed with hexapod-positioning systems in order to allow an exact and reproducible positioning of the optical CGH-based setup.

  8. Manufacture of aspherical molding dies for x-ray telescopes after ASTRO-H

    Namba, Yoshiharu; Beaucamp, Anthony; Matsumoto, Hironori; Tamura, Keisuke; Tawara, Yuzuru; Kunieda, Hideyo; Takahashi, Tadayuki


    Producing X-ray imaging space telescopes is a very expensive endeavor, due in great part to the difficulty of fabricating thin mirrors for Wolter type-I optical assemblies. To meet this challenge, replication from optical molding dies (also called mandrels) has become the preferred method, as it is reliable and economical. Several replication methods exist: in the case of the ASTRO-H mission, DC magnetron sputtering was used to deposit Pt/C multilayer coating on glass molding dies. The multilayer coating was then bonded with epoxy to aluminum shells and then separated from the die. Another mirror replication method consists of slumping thin glass sheets over a full (or a section of) revolution molding die under high temperature. This method was demonstrated in the case of the NuSTAR mission. But the challenge of fabricating truly aspheric Wolter type molding dies, which are capable of highly accurate angular resolution (below 5 arcs), remains very expensive and time consuming. In this paper, three methods for producing X-ray optic molding dies are presented. Each method uses a different substrate material and process chain, as follows: electroless nickel plated aluminum (first diamond turned then correctively polished), fused silica (first precision ground then correctively polished), and CVD silicon carbide (which can be finished entirely with a newly developed Shape Adaptive Grinding process). The process chains employed for each method are explained in details, and their relative merits discussed. A way forward for the next generation of X-ray telescopes after ASTRO-H is then drawn out.

  9. Development of a Fresnel lens for cold neutrons based on neutron refractive optics

    We have developed compound refractive lenses (CRLs) for cold neutrons, which are made of vitreous silica and have an effective potential of (90.1-2.7x10-4i) neV. In the case of compound refractive optics, neutron absorption by the material deteriorates lens performance. Thus, to prevent an increase in neutron absorption with increasing beam size, we have developed Fresnel lenses using the electrolytic in-process dressing grinding technique. The lens characteristics were carefully investigated with experimental and numerical simulation studies. The lenses functioned as a neutron focusing lens, and the focal length of 14 m was obtained with a 44-element series of the Fresnel lenses for 10 A neutrons. Moreover, good neutron transmission of 0.65 for 15 A neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possible to realize a CRL for practical use by choosing a suitable lens shape and material

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

    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

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

    Harris, Michael D., E-mail: [Department of Orthopaedics, Department of Bioengineering, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Kapron, Ashley L., E-mail: [Department of Orthopaedics, Department of Bioengineering, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Peters, Christopher L., E-mail: [Department of Orthopaedics, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Anderson, Andrew E., E-mail: [Department of Orthopaedics, Department of Bioengineering, Department of Physical Therapy, Scientific Computing and Imaging Institute, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States)


    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.

  12. Glass capillary X-ray lens: fabrication technique and ray tracing calculations

    A new method for producing a compound refractive X-ray lens is described. The lens is designed as glass capillary filled by a set of concave individual lenses. The method is appropriate for the preparation of 10-1000 spherical lenses in a glass capillary with a diameter of 0.1-1 mm. Lens aberrations are considered and simple formulas for spot size are derived. Ray-tracing simulations on the focusing experiments using 18 keV X-rays are reported

  13. Electrowetting liquid lens array on curved substrates for wide field of view image sensor

    Bang, Yousung; Lee, Muyoung; Won, Yong Hyub


    In this research, electrowetting liquid lens array on curved substrates is developed for wide field of view image sensor. In the conventional image sensing system, this lens array is usually in the form of solid state. However, in this state, the lens array which is similar to insect-like compound eyes in nature has several limitations such as degradation of image quality and narrow field of view because it cannot adjust focal length of lens. For implementation of the more enhanced system, the curved array of lenses based on electrowetting effect is developed in this paper, which can adjust focal length of lens. The fabrication of curved lens array is conducted upon the several steps, including chamber fabrication, electrode & dielectric layer deposition, liquid injection, and encapsulation. As constituent materials, IZO coated convex glass, UV epoxy (NOA 68), DI water, and dodecane are used. The number of lenses on the fabricated panel is 23 by 23 and each lens has 1mm aperture with 1.6mm pitch between adjacent lenses. When the voltage is applied on the device, it is observed that each lens is changed from concave state to convex state. From the unique optical characteristics of curved array of liquid lenses such as controllable focal length and wide field of view, we can expect that it has potential applications in various fields such as medical diagnostics, surveillance systems, and light field photography.

  14. Fabrication of polycrystalline diamond refractive X-ray lens by femtosecond laser processing

    X-ray planar compound refractive lenses were fabricated from a polycrystalline diamond plate grown by chemical vapor deposition, by precise through cutting with femtosecond laser pulses. The lens geometry and the surface morphology were investigated with optical and scanning electron microscopy, while the material structure modification was analyzed by Raman spectroscopy. The results of the preliminary lens test at 9.25-keV X-rays are presented. (orig.)

  15. Fabrication of polycrystalline diamond refractive X-ray lens by femtosecond laser processing

    Kononenko, T.V.; Ralchenko, V.G.; Ashkinazi, E.E.; Konov, V.I. [General Physics Institute of Russian Academy of Sciences, Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' , Moscow (Russian Federation); Polikarpov, M.; Ershov, P. [Immanuel Kant Baltic Federal University, Functional Nanomaterials, Kaliningrad (Russian Federation); Kuznetsov, S.; Yunkin, V. [Institute of Microelectronics Technology RAS, Chernogolovka, Moscow region (Russian Federation); Snigireva, I. [European Synchrotron Radiation Facility, Grenoble (France)


    X-ray planar compound refractive lenses were fabricated from a polycrystalline diamond plate grown by chemical vapor deposition, by precise through cutting with femtosecond laser pulses. The lens geometry and the surface morphology were investigated with optical and scanning electron microscopy, while the material structure modification was analyzed by Raman spectroscopy. The results of the preliminary lens test at 9.25-keV X-rays are presented. (orig.)

  16. Fabrication of polycrystalline diamond refractive X-ray lens by femtosecond laser processing

    Kononenko, T. V.; Ralchenko, V. G.; Ashkinazi, E. E.; Polikarpov, M.; Ershov, P.; Kuznetsov, S.; Yunkin, V.; Snigireva, I.; Konov, V. I.


    X-ray planar compound refractive lenses were fabricated from a polycrystalline diamond plate grown by chemical vapor deposition, by precise through cutting with femtosecond laser pulses. The lens geometry and the surface morphology were investigated with optical and scanning electron microscopy, while the material structure modification was analyzed by Raman spectroscopy. The results of the preliminary lens test at 9.25-keV X-rays are presented.

  17. Influence of the circumferential speed of a resin bond grinding wheel on the properties of a ground aspheric surface

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

    Vol. 9442. Bellingham: SPIE-INT SOC OPTICAL ENGINEERING, 2015 - (Kovačičinová, J.; Vít, T.), 94420T-94420T. (SPIE). ISBN 978-1-62841-557-5. ISSN 0277-786X. [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Aspheric grinding * resin bond * tool circumferential speed optimization Subject RIV: JP - Industrial Processing


    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:, E-mail: [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)


    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.

  19. Planar immersion lens with metasurfaces

    Ho, John S; Tanabe, Yuji; Yeh, Alexander J; Fan, Shanhui; Poon, Ada S Y


    The solid immersion lens is a powerful optical tool that allows light entering material from air or vacuum to focus to a spot much smaller than the free-space wavelength. Conventionally, however, they rely on semispherical topographies and are non-planar and bulky, which limits their integration in many applications. Recently, there has been considerable interest in using planar structures, referred to as metasurfaces, to construct flat optical components for manipulating light in unusual ways. Here, we propose and demonstrate the concept of a planar immersion lens based on metasurfaces. The resulting planar device, when placed near an interface between air and dielectric material, can focus electromagnetic radiation incident from air to a spot in material smaller than the free-space wavelength. As an experimental demonstration, we fabricate an ultrathin and flexible microwave lens and further show that it achieves wireless energy transfer in material mimicking biological tissue.

  20. Lens system for SIMS analysis

    A powerful version of the charge-density method is applied to the study of a combined objective and emission lens, suitable for highly localized analysis of a flat sample surface. This lens can extract secondary ions of equal or opposite polarity to that of the primary particles. A computer simulation of the ion trajectories for both modes is made. The behaviour for different values of the geometric parameters and polarizations is analyzed and useful data for design such as primary beam demagnification and secondary image position are given. (author) 4 refs

  1. Broken intraocular lens during cataract surgery.

    Kirkpatrick, J N; Cook, S D


    A case of planned routine extracapsular cataract extraction is described where surgery was complicated peroperatively by fracture of the posterior chamber lens implant. The technique of lens implantation is discussed.

  2. Transferable aspherical atom model refinement of protein and DNA structures against ultrahigh-resolution X-ray data.

    Malinska, Maura; Dauter, Zbigniew


    In contrast to the independent-atom model (IAM), in which all atoms are assumed to be spherical and neutral, the transferable aspherical atom model (TAAM) takes into account the deformed valence charge density resulting from chemical bond formation and the presence of lone electron pairs. Both models can be used to refine small and large molecules, e.g. proteins and nucleic acids, against ultrahigh-resolution X-ray diffraction data. The University at Buffalo theoretical databank of aspherical pseudo-atoms has been used in the refinement of an oligopeptide, of Z-DNA hexamer and dodecamer duplexes, and of bovine trypsin. The application of the TAAM to these data improves the quality of the electron-density maps and the visibility of H atoms. It also lowers the conventional R factors and improves the atomic displacement parameters and the results of the Hirshfeld rigid-bond test. An additional advantage is that the transferred charge density allows the estimation of Coulombic interaction energy and electrostatic potential. PMID:27303797

  3. The Influence of the Aspheric Profiles for Transition Zone on Optical Performance of Human Eye After Conventional Ablation

    Fang, L.


    The analysis in the impact of transition zone on the optical performance of human eye after laser refractive surgery is important for improving visual correction technology. By designing the ablation profiles of aspheric transition zone and creating the ablation profile for conventional refractive surgery in optical zone, the influence of aspheric transition zone on residual aberrations was studied. The results indicated that the ablation profiles of transition zone had a significant influence on the residual wavefront aberrations. For a hyperopia correction, the profile #9 shows a larger induced coma and spherical aberration when the translation of the centre of pupil remains constant. However, for a myopia astigmatism correction, the induced coma and spherical aberration in profile #1 shows relatively larger RMS values than those in other profiles. Therefore, the residual higher order aberrations may be decreased by optimizing ablation profiles of transition zone, but they cannot be eliminated. In order to achieve the best visual performance, the design of ablation pattern of transition zone played a crucial role.

  4. A broadband transformation-optics metasurface lens

    Wan, Xiang; Xiang Jiang, Wei; Feng Ma, Hui; Jun Cui, Tie, E-mail: [State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096 (China)


    We present a transformational metasurface Luneburg lens based on the quasi-conformal mapping method, which has weakly anisotropic constitutive parameters. We design the metasurface lens using inhomogeneous artificial structures to realize the required surface refractive indexes. The transformational metasurface Luneburg lens is fabricated and the measurement results demonstrate very good performance in controlling the radiated surface waves.

  5. 21 CFR 886.3600 - Intraocular lens.


    ... the natural lens of an eye. (b) Classification. Class III. (c) Date PMA or notice of completion of a... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intraocular lens. 886.3600 Section 886.3600 Food... DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3600 Intraocular lens. (a) Identification....

  6. 21 CFR 886.1400 - Maddox lens.


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Maddox lens. 886.1400 Section 886.1400 Food and... OPHTHALMIC DEVICES Diagnostic Devices § 886.1400 Maddox lens. (a) Identification. A Maddox lens is a device... intended to be handheld or placed in a trial frame to evaluate eye muscle dysfunction. (b)...

  7. Diabetes and contact lens wear.

    O'Donnell, Clare; Efron, Nathan


    The literature suggests that diabetic patients may have altered tear chemistry and tear secretion as well as structural and functional changes to the corneal epithelium, endothelium and nerves. These factors, together with a reported increased incidence of corneal infection, suggest that diabetic patients may be particularly susceptible to developing ocular complications during contact lens wear. Reports of contact lens-induced complications in diabetic patients do exist, although a number of these reports concern patients with advanced diabetic eye disease using lenses on an extended wear basis. Over the past decade or so, there have been published studies documenting the response of the diabetic eye to more modern contact lens modalities. The results of these studies suggest that contact lenses can be a viable mode of refractive correction for diabetic patients. Furthermore, new research suggests that the measurement of tear glucose concentration could, in future, be used to monitor metabolic control non-invasively in diabetic patients. This could be carried out using contact lenses manufactured from hydrogel polymers embedded with glucose-sensing agents or nanoscale digital electronic technology. The purpose of this paper is to review the literature on the anterior ocular manifestations of diabetes, particularly that pertaining to contact lens wear. PMID:22537249

  8. Radiation damage of the lens

    Explained is the cataract as the lens is one of the most sensitive tissues to radiation, for considering the possible ophthalmological radiation disorder by the Fukushima Nuclear Power Plant Accident (2011). Radiation cataract is observed at 1-2 years after acute high dose exposure, but at low dose, it appears as the late effect. In fact, the disease related to exposure is found in as many as 25% of Chernobyl workers at >10 years post its Accident. Pathologic feature of radiation cataract has been thought to be the posterior subcapsular type. However, the cortical type is shown to be also noted by recent findings in the Chernobyl Accident, in the lens 30-45 years after radiotherapy of infants for dermovascular angioma, in astronaut, and in Hiroshima A-bomb survivors. Acute exposure to 0.5-1.5 Gy results in lens opacity and at >5 Gy, cataract with visual dysfunction. Higher cataract prevalence is recently reported seen in the therapeutic cardiac fluoroscopy where the medians of accumulated doses are 6.0 Sv in doctors and 1.5 Sv in nurses and radiologists. Astronauts exposed at >8 mSv have higher prevalence. Animal experiments have shown that the lens sensitivity to radiation depends on the age. Clinical experience of radiotherapy of the angioma above has suggested the higher sensitivity in young generation, which is supported by the fact that, among 114 inhabitants of 60Co-contaminated building, the dose effect is observable in 61 inhabitants of the age <20 y alone. linear threshold theory (LNT) hypothesis cannot be excluded by above evidences and there is conceivably no (or extremely low) threshold for cataract. The younger the age of exposure, the higher the risk of cataract, and thereby the lens in young generation should be carefully followed-up in Fukushima. (T.T.)

  9. Modern lens antennas for communications engineering

    Thornton, John


    The aim of this book is to present the modern design principles and analysis of lens antennas. It gives graduates and RF/Microwave professionals the design insights in order to make full use of lens antennas.  Why do we want to write a book in lens antennas? Because this topic has not been thoroughly publicized, its importance is underestimated. As antennas play a key role in communication systems, recent development in wireless communications would indeed benefit from the characteristics of lens antennas: low profile, and low cost etc.  The major advantages of lens antennas are na

  10. Micro-optic lens for data storage

    Milster, T. D.; Trusty, R. M.; Wang, M. S.; Froehlich, F. F.; Erwin, J. Kevin


    A new type of microlens for data storage applications that has improved off-axis performance is described. The lens consists of a micro Fresnel pattern on a curved substrate. The radius of the substrate is equal to the focal length of the lens. If the pattern and substrate are thin, the combination satisfies the Abbe sine condition. Therefore, the lens is free of coma. We analyze a 0.5 numerical aperture, 0.50 mm focal length lens in detail. A 0.16 numerical aperture lens was fabricated holographically, and results are presented.

  11. Lactate Dehydrogenase Isoenzyme of Lens in Fetus

    Kexi Ding; Yasong Zhang


    Purpose: The LDH isoenzyme patterns were evaluated in lens of fetus to study the metabolism in human lenses.Methods: LDH isoenzyme electrophoresis was performed in 15 lenses of human fetus aged from 4~6 months.Results: There are 5 bands of LDH in fetus lens. LDH4 lever is the highest, and LDH1 is the lowest, especially in the cortex of lens. LDH1 is higher in lens of 4 months of age than in that of 5 and 6 months of age.Conclusions: LDH isoenzyme in lens of fetus shows mainly anaerobic metabolism in development, but there is also aerobic metabolism, especially in younger fetus.

  12. Conjunctival impression cytology in contact lens wearers.

    Simon Priya


    Full Text Available PURPOSE: To evaluate the cytological changes in conjunctiva following regular contact lens wear and to determine the correlation, if any, between severity of cytological alteration and symptoms related to contact lens wear. METHODS: One hundred eyes (50 normal asymptomatic subjects who served as a control group were studied by conjunctival impression cytology (CIC. These subjects were fitted with rigid gas permeable (RGP or soft contact lenses and were followed up at the end of 3 and 6 months. At each follow-up visit the CIC was repeated. A filter paper with the impression specimen was stained with periodic acid schiff (PAS and haematoxylin stain to study goblet cell loss. Papanicolaou stain was done to study squamous metaplasia. The cytological changes were graded using the system described by Natadisastra et al. RESULTS: Severity of cytological changes increased with the duration of contact lens wear (P = 0.00001. At the end of 6 months, 60% of symptomatic eyes wearing soft contact lens and RGP lens showed abnormal CIC changes. None of the asymptomatic RGP contact lens wearing eyes showed abnormal CIC changes whereas 33.4% of the asymptomatic soft contact lens wearing eyes showed abnormal CIC changes (P = 0.033. Epithelial changes occurred within 3-6 months of contact lens fitting. CONCLUSION: Severity of cytological changes increased with duration of lens wear (P = 0.00001. Prevalence and severity of cytological alteration is more in symptomatic contact lens wearers. Soft contact lens wearers although asymptomatic showed severe CIC changes.

  13. Contact lens surface by electron beam

    Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility

  14. Contact lens surface by electron beam

    Shin, Jung Hyuck [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Suk Ju; Hwang, Kwang Ha; Jeon Jin [Dongshin Univ., Naju (Korea, Republic of)


    Contact lens materials needs good biocompatibility, high refractive index, high optical transparency, high water content etc. Surface treat method by using plasma and radiation can modify the physical and/or chemical properties of the contact lens surface. Radiation technology such as electron beam irradiation can apply to polymerization reaction and enhance the functionality of the polymer.The purpose of this study is to modify of contact lens surface by using Eb irradiation technology. Electron beam was irradiated to the contact lens surface which was synthesized thermal polymerization method and commercial contact lens to modify physical and chemical properties. Ft-IR, XP, UV-vis spectrophotometer, water content, oxygen trans-metastability were used to characterize the surface state, physicochemical, and optical property of the contact lens treated with Eb. The water content and oxygen transmissibility of the contact lens treated with Eb were increased due to increase in the hydrophilic group such as O-C=O and OH group on the contact lens surface which could be produced by possible reaction between carbon and oxygen during the Eb irradiation. All of the lenses showed the high optical transmittance above 90%. In this case of B/Es, TES, Ti contact lens, the optical transmittance decreased about 5% with increasing Eb dose in the wavelength of UV-B region. The contact lens modified by Eb irradiation could improve the physical properties of the contact lens such as water content and oxygen transmissibility.

  15. Biomimetic accommodating lens with implementation in MEMS

    Hogan, Alexander L.; Baker, Brian; Fisher, Charles; Naylor, Stephen; Fettig, Doug; Harvey, Ian R.


    We describe an accommodating lens patterned after the crystalline lens of the eye. Our biomimetic MEMS design calls to mind the zonules of zinn which pull radially to stretch the crystalline lens of the eye to modify the optical path. We present initial characterization of the prototype macro-scale device constructed through traditional machining techniques and using a PDMS polymer lens. Testing of the macro-scale lens indicated a 22% change in focal length through the range of radial stretching, with degradation of the spherical lens shape but no hysteresis after low-cycle testing. We also demonstrate a MEMS implementation of the lens actuator constructed using the Sandia SUMMiT-V ™ surface micromachining process. The optical path of this system is approximately 300 microns in diameter, providing a platform to potential applications improving mobile camera optics and medical imaging.


    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: [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan)


    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. Charting paths through gravity's lens

    Features of gravitational lenses are described, together with several examples of seemingly identical celestial objects which were later proved to be the same object. The first evidence was concerned with the object 0957+561, which featured two quasars 6 arcsec apart that displayed equal redshifts, magnitudes, and recession velocities, while the northern component exhibited 30 percent weaker emission and absorption. It was suggested that a galaxy interposed between the earth and a quasar was deflecting its emissions and causing it to be viewed as two distinct objects, i.e., a gravitational lens existed. Later evidence for the intervening galaxy was found, and also permitted attributing the anomalous redshift observed to a contribution from the galaxy. The light bending effect is predicted by the General Theory of Relativity, and is illustated in terms of a point mass, convex lens, and a galaxy

  18. Lens transglutaminase and cataract formation.

    Lorand, L.; Hsu, L K; Siefring, G E; Rafferty, N S


    A protein polymer characteristically present in human cataract was shown to contain significant amounts of gamma-glutamyl-epsilon-lysine isopeptides. It is proposed that these crosslinks are produced by the action of transglutaminase (R-glutaminyl-peptide:amine-gamma-glutamyl-yltransferase, EC, which is all the more plausible because lens contains the enzyme and endogenous protein substrates for it. The enzyme is similar to that obtained from liver and is Ca2+ dependent. Highest app...

  19. Lens Coupled Quantum Cascade Laser

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)


    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  20. Fresnel Lens with Embedded Vortices

    Sunil Vyas; Rakesh Kumar Singh; Devinder Pal Ghai; Senthilkumaran, P.


    Vortices of different charges are embedded in a wavefront that has quadratic phase variation, and the intensity distribution near the focal plane is studied. This method may be useful in realizing complicated beam profiles. We have experimentally demonstrated the generation of vortex arrays having integer as well as fractional topological charges that produce different intensity profiles at the focal plane. The phase variation realized on a spatial light modulator (SLM) acts as a Fresnel lens...

  1. Glycation precedes lens crystallin aggregation

    Non-enzymatic glycosylation (glycation) seems to have the potential to alter the structure of crystallins and make them susceptible to thiol oxidation leading to disulfide-linked high molecular weight (HMW) aggregate formation. They used streptozotocin diabetic rats during precataract and cataract stages and long-term cell-free glycation of bovine lens crystallins to study the relationship between glycation and lens crystallin aggregation. HMW aggregates and other protein components of the water-soluble (WS) and urea-soluble (US) fractions were separated by molecular sieve high performance liquid chromatography. Glycation was estimated by both [3H]NaBH4 reduction and phenylboronate agarose affinity chromatography. Levels of total glycated protein (GP) in the US fractions were about 2-fold higher than in the WS fractions and there was a linear increase in GP in both WS and US fractions. This increase was parallelled by a corresponding increase in HMW aggregates. Total GP extracted by the affinity method from the US fraction showed a predominance of HMW aggregates and vice versa. Cell-free glycation studies with bovine crystallins confirmed the results of the animals studies. Increasing glycation caused a corresponding increase in protein insolubilization and the insoluble fraction thus formed also contained more glycated protein. It appears that lens protein glycation, HMW aggregate formation, and protein insolubilization are interrelated

  2. Aging Changes of Lens Physical Properties

    Kudryavtseva Y.V.


    Full Text Available The aim of the work is to assess aging changes of lens physical properties. Materials and Methods. There have been examined the patients aged 57—90 years. 73 lens nuclei with cataract of different maturity degree taken by means of extracapsular cataract extraction have been studied. Before the operation there has been determined relative echodensity of lens according to an original technique and assessed the lens colour and nuclear mass. Results. Brown colour of the lens nucleus is slightly increasing with years (r=0.4; р<0.05. Mean value of relative lens echodensity is 0.59±0.01. An average mass of lens nucleus is 98.3±1.0 mg, and its average density is 1312.0±12.0 mg/m2. Mature cataract is revealed to be not always hard (r=0.4; р<0.05, i.e. in this case the relation is inverse. When lens density increases, mechanical hardness of its nucleus grows up (r=0.4, р<0.05. At the same time mechanical density of lens nucleus increases with the increase of years (r=0.74, р<0.05. Age is stated not to be a controlling factor in cataract occurring and progressing. Conclusion. Lens mechanical characteristics depend on its chemical composition, and in aging brown colour of the lens increases, mechanical density of lens nucleus grows up, and vision can change slightly. Cataract maturation and the increase of lens density are chemically different processes and independent of each other.

  3. Adaptive liquid lens driven by elastomer actuator

    Jin, Boya; Lee, Ji-Hyeon; Zhou, Zuowei; Zhang, Guoqing; Lee, Gi-Bbeum; Ren, Hongwen; Nah, Changwoon


    When a liquid droplet is filled in the hole of a dielectric elastomer (DE) film, a liquid lens is prepared. By applying a DC voltage to the DE film, the liquid lens can be actuated. As a comparison, two liquid lenses, one in a millimeter scale and the other in a submillimeter scale, are demonstrated. In a relaxed state, the focal length of each liquid lens is the longest. In an actuated state, the diameter of each lens is reduced. As a result, their focal length is tuned. Here, the DE film functions as an actuator. Due to the biconvex shape and smooth liquid surface, each liquid lens can provide good optical performance. They also possess the merits of simple fabrication, compact structure, and easy operation. In contrast to the bigger liquid lens, the smaller one can present a better mechanical stability without the concern of the gravitational effect.

  4. Laser differential confocal lens thickness measurement

    Based on the property that the absolute zero of an axial intensity curve exactly corresponds to the focus of the objective in a differential confocal system (DCS), a new laser differential confocal lens thickness measurement is proposed to achieve the high-precision non-contact measurement of lens thickness. The proposed approach uses the absolute zero of DCS axial response curve to precisely identify the vertexes of the test lens, obtains the central optical thickness of the test lens, and then uses the radius of curvature and refractive index of the test lens and the ray tracing facet iterative calculation to obtain the central geometrical thickness of the test lens. The theoretical analyses and preliminary experiments indicate that the measurement accuracy is better than 0.03%. (paper)

  5. Eye model with controllable lens scattering

    Paeglis, R; Ozolinsh, M; Cikmacs, P; Andersson-Engels, Stefan


    A model of human eye for experiments in vision research has been developed using PLZT ceramics. This ``artificial eye{''} allows to simulate light scattering caused by cataract in the eye lens. Light scattering of a composite eye lens of the model depends on the electric field applied to a transparent electrooptic PLZT ceramics plate that is attached directly to the lens. The image degradation in such a model eye at various degrees of scattering is studied observing and recording the ...

  6. The lens and source of the optical Einstein ring gravitational lens ER 0047-2808

    Wayth, Randall B.; Warren, Stephen J.; Lewis, Geraint F.; Hewett, Paul C.


    (Abridged) We perform a detailed analysis of the optical gravitational lens ER 0047-2808 imaged with WFPC2 on the Hubble Space Telescope. Using software specifically designed for the analysis of resolved gravitational lens systems, we focus on how the image alone can constrain the mass distribution in the lens galaxy. We find the data are of sufficient quality to strongly constrain the lens model with no a priori assumptions about the source. Using a variety of mass models, we find statistica...

  7. Role of Aquaporin 0 in lens biomechanics

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5−/−), AQP0 KO (heterozygous KO: AQP0+/−; homozygous KO: AQP0−/−; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0+/− lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  8. Double-mirror peripheral vitrectomy lens.

    Ohji, M; Tano, Y


    Many surgeons use prism lenses to see the periphery of the fundus during vitrectomy; however, chromatic aberrations in higher-power prismatic lenses cause blurring of the peripheral image. For better visualization of the periphery of the fundus, we developed a new contact lens, the double-mirror peripheral vitrectomy lens. The new lens is a quartz cylinder with two mirrors, and it provides a crisp, clear, upright image of much more of the peripheral fundus than is visible through conventional prism lenses. The new lens also provides a wider area of view than conventional prism lenses. PMID:7487611

  9. Stretchable Binary Fresnel Lens for Focus Tuning.

    Li, Xueming; Wei, Lei; Poelma, René H; Vollebregt, Sten; Wei, Jia; Urbach, Hendrik Paul; Sarro, Pasqualina M; Zhang, Guo Qi


    This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material combines the excellent optical absorption properties of the CNT with the transparency and stretchability of the PDMS. By stretching the elastomeric composite in radial direction, the lens focal length is tuned. Good focusing response is demonstrated and a large focus change (≥24%) was achieved by stretching lenses up to 11.4%. PMID:27139747

  10. A Magnification Lens for Interactive Volume Visualization

    LaMar, E; Hamann, B; Joy, K I


    Volume visualization of large data sets suffers from the same problem that many other visualization modalities suffer from: either one can visualize the entire data set and lose small details or visualize a small region and lose the context. In this paper, they present a magnification lens technique for volume visualization. While the notion of a magnification-lens is not new, and other techniques attempt to simulate the physical properties of a magnifying lens, their contribution is in developing a magnification lens that is fast, can be implemented using a fairly small software overhead, and has a natural, intuitive appearance. The issue with magnification lens is the border, or transition, region. The lens center and exterior have a constant zoom factor, and are simple to render. It is the border region that blends between the external and interior magnification, and has a non-constant magnification. They use the perspective-correct textures capability, available in most current graphics systems, to produce a lens with a tessellated border region that approximates linear compression with respect to the radius of the magnification lens. They discuss how a cubic border can mitigate the discontinuities resulting from the use of a linear function, without significant performance loss. They discuss various issues concerning development of a three-dimensional magnification lens.