WorldWideScience

Sample records for chromatic aberration correction

  1. Correcting the Chromatic Aberration in Barrel Distortion of Endoscopic Images

    Directory of Open Access Journals (Sweden)

    Y. M. Harry Ng

    2003-04-01

    Full Text Available Modern endoscopes offer physicians a wide-angle field of view (FOV for minimally invasive therapies. However, the high level of barrel distortion may prevent accurate perception of image. Fortunately, this kind of distortion may be corrected by digital image processing. In this paper we investigate the chromatic aberrations in the barrel distortion of endoscopic images. In the past, chromatic aberration in endoscopes is corrected by achromatic lenses or active lens control. In contrast, we take a computational approach by modifying the concept of image warping and the existing barrel distortion correction algorithm to tackle the chromatic aberration problem. In addition, an error function for the determination of the level of centroid coincidence is proposed. Simulation and experimental results confirm the effectiveness of our method.

  2. Adaptive dispersion formula for index interpolation and chromatic aberration correction.

    Science.gov (United States)

    Li, Chia-Ling; Sasián, José

    2014-01-13

    This paper defines and discusses a glass dispersion formula that is adaptive. The formula exhibits superior convergence with a minimum number of coefficients. Using this formula we rationalize the correction of chromatic aberration per spectrum order. We compare the formula with the Sellmeier and Buchdahl formulas for glasses in the Schott catalogue. The six coefficient adaptive formula is found to be the most accurate with an average maximum index of refraction error of 2.91 × 10(-6) within the visible band.

  3. The investigation of chromatic aberration correction for digital eye fundus images

    OpenAIRE

    Jakstys, V.; Marcinkevicius, V.; Treigys, P.

    2016-01-01

    This paper focuses on the lateral chromatic aberration correction in images captured with Optomed SmartScope M5 camera. This portable non-mydriatic eye fundus orbital camera does not have chromatic lenses. When photo camera system is designed without chromatic lenses, it is necessary to apply image processing algorithms for lateral chromatic aberration effect correction. These algorithms try to scale the fringed colour channels so that all channels spatially overlap each other ...

  4. A method of dynamic chromatic aberration correction in low-voltage scanning electron microscopes.

    Science.gov (United States)

    Khursheed, Anjam

    2005-07-01

    A time-of-flight concept that dynamically corrects for chromatic aberration effects in scanning electron microscopes (SEMs) is presented. The method is predicted to reduce the microscope's chromatic aberration by an order of magnitude. The scheme should significantly improve the spatial resolution of low-voltage scanning electron microscopes (LVSEMs). The dynamic means of correcting for chromatic aberration also allows for the possibility of obtaining high image resolution from electron guns that have relatively large energy spreads.

  5. Correction of chromatic aberrations at television registration of image through protective viewing systems

    Science.gov (United States)

    Kulyas, Oleg L.; Nikitin, Konstantin A.

    2016-03-01

    Ways of chromatic aberration in images are examined and analyzed which are generated at television supervision through protective glasses of a considerable thickness. The results of experimental check up of the given method of correction is introduced and described.

  6. Effect of chromatic aberration on atomic-resolved spherical aberration corrected STEM images.

    Science.gov (United States)

    Kuramochi, Koji; Yamazaki, Takashi; Kotaka, Yasutoshi; Ohtsuka, Masahiro; Hashimoto, Iwao; Watanabe, Kazuto

    2009-12-01

    The effect of the chromatic aberration (C(c)) coefficient in a spherical aberration (C(s))- corrected electromagnetic lens on high-resolution high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) images is explored in detail. A new method for precise determination of the C(c) coefficient is demonstrated, requiring measurement of an atomic-resolution one-frame through-focal HAADF STEM image. This method is robust with respect to instrumental drift, sample thickness, all lens parameters except C(c), and experimental noise. It is also demonstrated that semi-quantitative structural analysis on the nanometer scale can be achieved by comparing experimental C(s)- corrected HAADF STEM images with their corresponding simulated images when the effects of the C(c) coefficient and spatial incoherence are included.

  7. Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction.

    Science.gov (United States)

    Prasad, Dilip K; Brown, Michael S

    2014-01-01

    A macro-filter-lens design that can correct for chromatic and geometric aberrations simultaneously while providing for a long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected for by the lens element (plano-convex), which makes the output rays parallel to the optic axis. This macro-filter-lens design does not need additional macro lenses and it provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.

  8. Camera processing with chromatic aberration.

    Science.gov (United States)

    Korneliussen, Jan Tore; Hirakawa, Keigo

    2014-10-01

    Since the refractive index of materials commonly used for lens depends on the wavelengths of light, practical camera optics fail to converge light to a single point on an image plane. Known as chromatic aberration, this phenomenon distorts image details by introducing magnification error, defocus blur, and color fringes. Though achromatic and apochromatic lens designs reduce chromatic aberration to a degree, they are complex and expensive and they do not offer a perfect correction. In this paper, we propose a new postcapture processing scheme designed to overcome these problems computationally. Specifically, the proposed solution is comprised of chromatic aberration-tolerant demosaicking algorithm and post-demosaicking chromatic aberration correction. Experiments with simulated and real sensor data verify that the chromatic aberration is effectively corrected.

  9. Information transfer in a TEM corrected for spherical and chromatic aberration.

    Science.gov (United States)

    Haider, M; Hartel, P; Müller, H; Uhlemann, S; Zach, J

    2010-08-01

    For the transmission electron aberration-corrected microscope (TEAM) initiative of five U.S. Department of Energy laboratories in the United States, a correction system for the simultaneous compensation of the primary axial aberrations, the spherical aberration Cs, and the chromatic aberration Cc has been developed and successfully installed. The performance of the resulting Cc /Cs-corrected TEAM instrument has been investigated thoroughly. A significant improvement of the linear contrast transfer can be demonstrated. The information about the instrument one obtains using Young's fringe method is compared for uncorrected, Cs-corrected, and Cc /Cs-corrected instruments. The experimental results agree well with simulations. The conclusions might be useful to others in understanding the process of image formation in a Cc /Cs-corrected transmission electron microscope.

  10. Simultaneous and independent adaptive correction of spherical and chromatic aberration using an electron mirror and lens combination.

    Science.gov (United States)

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2012-04-01

    We present a theoretical analysis of an electrostatic triode mirror combined with an einzel lens for the correction of spherical and chromatic aberration. We show that this device adaptively corrects spherical and chromatic aberration simultaneously and independently. Chromatic aberration can be compensated over a relative range of -38% to +100%, and spherical aberration over ±100% range. We compare the analytic calculation with a numerical simulation and show that the two descriptions agree to within 5% in the relevant operating regime of the device.

  11. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV

    Science.gov (United States)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max.; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-01

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed Cc/Cs corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  12. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

    Science.gov (United States)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-12

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  13. Chromatic aberration correction of the human eye for retinal imaging in the near infrared.

    Science.gov (United States)

    Fernández, Enrique J; Unterhuber, Angelika; Povazay, Boris; Hermann, Boris; Artal, Pablo; Drexler, Woflgang

    2006-06-26

    An achromatizing lens has been designed for the human eye in the near infrared range, from 700 to 900 nm, for retinal imaging purposes. Analysis of the performance of the lens, including tolerance to misalignments, has been mathematically accomplished by using an existing eye model. The calculations have shown a virtually perfect correction of the ocular longitudinal chromatic aberration, while still keeping a high optical quality. Ocular aberrations in five subjects have been measured with and without the achromatizing lens by using a Hartmann-Shack wavefront sensor and a broad bandwidth femtosecond Ti:sapphire laser in the spectral range of interest with a set of interference filters, studying the benefits and limits in the use of the achromatizing lens. Ocular longitudinal chromatic aberration has been experimentally demonstrated to be fully corrected by the proposed lens, with no induction of any other parasitic aberration. The practical implementation of the achromatizing lens for Ophthalmoscopy, specifically for optical coherence tomography where the use of polychromatic light sources in the near infrared portion of the spectrum is mandatory, has been considered. The potential benefits of using this lens in combination with adaptive optics to achieve a full aberration correction of the human eye for retinal imaging have also been discussed.

  14. Low-Beta Insertions inducing Chromatic Aberrations in Storage Rings and their Local and Global Correction

    CERN Document Server

    Fartoukh, S

    2010-01-01

    The chromatic aberrations induced by low-β insertions can seriously limit the performance of circular colliders. The impact is twofold: (1) a substantial off-momentum beta-beating wave traveling around the ring and leading to a net reduction of the mechanical aperture of the low-beta quadrupoles but also impacting on the hierarchy of the collimator and protection devices of the machine, (2) a huge non-linear chromaticity which, when combined with the magnetic imperfections of the machine, could substantially reduce the momentum acceptance of the ring by pushing slightly off-momentum particles towards non-linear resonances. These effects will be analyzed and illustrated in the framework of the LHC insertions upgrade Phase I [1] and a strategy for correction will be developed, requiring a deep modification of the LHC overall optics.

  15. Low-Beta insertions inducing chromatic aberrations in storage rings and their local and global correction

    CERN Document Server

    Fartoukh, S

    2010-01-01

    The chromatic aberrations induced by low-β insertions can seriously limit the performance of circular colliders. The impact is twofold: (1) a substantial off-momentum beta-beating wave traveling around the ring and leading to a net reduction of the mechanical aperture of the lowbeta quadrupoles but also impacting on the hierarchy of the collimator and protection devices of the machine, (2) a huge non-linear chromaticity which, when combined with the magnetic imperfections of the machine, could substantially reduce the momentum acceptance of the ring by pushing slightly off-momentum particles towards non-linear resonances. These effects will be analyzed and illustrated in the framework of the LHC insertions upgrade Phase I [1] and a strategy for correction will be developed, requiring a deep modification of the LHC overall optics.

  16. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets.

    Science.gov (United States)

    Wüstner, Daniel; Faergeman, Nils J

    2008-08-01

    Intrinsically fluorescent sterols, like dehydroergosterol (DHE), mimic cholesterol closely and are therefore suitable to determine cholesterol transport by fluorescence microscopy. Disadvantages of DHE are its low quantum yield, rapid bleaching, and the fact that its excitation and emission is in the UV region of the spectrum. Thus, one has to deal with chromatic aberration and low signal-to-noise ratio. We developed a method to correct for chromatic aberration between the UV channel and the red/green channel in multicolor imaging of DHE compared with the lipid droplet marker Nile Red in living macrophage foam cells and in adipocytes. We used deconvolution microscopy and developed image segmentation techniques to assess the DHE content of lipid droplets in both cell types in an automated manner. Pulse-chase studies and colocalization analysis were performed to monitor the redistribution of DHE upon adipocyte differentiation. DHE is targeted to transferrin-positive recycling endosomes in preadipocytes but associates with droplets in mature adipocytes. Only in adipocytes but not in foam cells fluorescent sterol was confined to the droplet-limiting membrane. We developed an approach to visualize and quantify sterol content of lipid droplets in living cells with potential for automated high content screening of cellular sterol transport.

  17. Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction.

    Science.gov (United States)

    Zawadzki, Robert J; Cense, Barry; Zhang, Yan; Choi, Stacey S; Miller, Donald T; Werner, John S

    2008-05-26

    We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 x 3.5 x 3.5 microm(3). Critical to the instrument's resolution is a customized achromatizing lens that corrects for the eye's longitudinal chromatic aberration and an ultra broadband light source (Delta lambda=112 nm lambda(0)= approximately 836 nm). The eye's transverse chromatic aberrations is modeled and predicted to be sufficiently small for the imaging conditions considered. The achromatizing lens was strategically placed at the light input of the AO-OCT sample arm. This location simplifies use of the achromatizing lens and allows straightforward implementation into existing OCT systems. Lateral resolution was achieved with an AO system that cascades two wavefront correctors, a large stroke bimorph deformable mirror (DM) and a micro-electromechanical system (MEMS) DM with a high number of actuators. This combination yielded diffraction-limited imaging in the eyes examined. An added benefit of the broadband light source is the reduction of speckle size in the axial dimension. Additionally, speckle contrast was reduced by averaging multiple B-scans of the same proximal patch of retina. The combination of improved micron-scale 3D resolution, and reduced speckle size and contrast were found to significantly improve visibility of microscopic structures in the retina.

  18. Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing

    Science.gov (United States)

    Wang, Peng; Mohammad, Nabil; Menon, Rajesh

    2016-02-01

    We exploit the inherent dispersion in diffractive optics to demonstrate planar chromatic-aberration-corrected lenses. Specifically, we designed, fabricated and characterized cylindrical diffractive lenses that efficiently focus the entire visible band (450 nm to 700 nm) onto a single line. These devices are essentially pixelated, multi-level microstructures. Experiments confirm an average optical efficiency of 25% for a three-wavelength apochromatic lens whose chromatic focus shift is only 1.3 μm and 25 μm in the lateral and axial directions, respectively. Super-achromatic performance over the continuous visible band is also demonstrated with averaged lateral and axial focus shifts of only 1.65 μm and 73.6 μm, respectively. These lenses are easy to fabricate using single-step grayscale lithography and can be inexpensively replicated. Furthermore, these devices are thin (<3 μm), error tolerant, has low aspect ratio (<1:1) and offer polarization-insensitive focusing, all significant advantages compared to alternatives that rely on metasurfaces. Our design methodology offers high design flexibility in numerical aperture and focal length, and is readily extended to 2D.

  19. Quantitative Phase Microscopy of microstructures with extended measurement range and correction of chromatic aberrations by multiwavelength digital holography.

    Science.gov (United States)

    Ferraro, P; Miccio, L; Grilli, S; Paturzo, M; De Nicola, S; Finizio, A; Osellame, R; Laporta, P

    2007-10-29

    Quantitative Phase Microscopy (QPM) by interferometric techniques can require a multiwavelength configuration to remove 2pi ambiguity and improve accuracy. However, severe chromatic aberration can affect the resulting phase-contrast map. By means of classical interference microscope configuration it is quite unpractical to correct such aberration. We propose and demonstrate that by Digital Holography (DH) in a microscope configuration it is possible to clear out the QPM map from the chromatic aberration in a simpler and more effective way with respect to other approaches. The proposed method takes benefit of the unique feature of DH to record in a plane out-of-focus and subsequently reconstruct numerically at the right focal image plane. In fact, the main effect of the chromatic aberration is to shift differently the correct focal image plane at each wavelength and this can be readily compensated by adjusting the corresponding reconstruction distance for each wavelength. A procedure is described in order to determine easily the relative focal shift among different imaging wavelengths by performing a scanning of the numerical reconstruction along the optical axis, to find out the focus and to remove at the same time the chromatic aberration.

  20. Correction of axial and lateral chromatic aberration with false color filtering.

    Science.gov (United States)

    Chang, Joonyoung; Kang, Hee; Kang, Moon Gi

    2013-03-01

    In this paper, we propose a chromatic aberration (CA) correction algorithm based on a false color filtering technique. In general, CA produces color distortions called color fringes near the contrasting edges of captured images, and these distortions cause false color artifacts. In the proposed method, a false color filtering technique is used to filter out the false color components from the chroma-signals of the input image. The filtering process is performed with the adaptive weights obtained from both the gradient and color differences, and the weights are designed to reduce the various types of color fringes regardless of the colors of the artifacts. Moreover, as preprocessors of the filtering process, a transient improvement (TI) technique is applied to enhance the slow transitions of the red and blue channels that are blurred by the CA. The TI process improves the filtering performance by narrowing the false color regions before the filtering process when severe color fringes (typically purple fringes) occur widely. Last, the CA-corrected chroma-signal is combined with the TI chroma-signal to avoid incorrect color adjustment. The experimental results show that the proposed method substantially reduces the CA artifacts and provides natural-looking replacement colors, while it avoids incorrect color adjustment.

  1. Correcting lateral chromatic aberrations in non-monochromatic X-ray microscopy

    Science.gov (United States)

    Falch, Ken Vidar; Detlefs, Carsten; Di Michiel, Marco; Snigireva, Irina; Snigirev, Anatoly; Mathiesen, Ragnvald H.

    2016-08-01

    Lateral chromatic aberration in microscopy based on refractive optics may be reduced significantly by adjustments to the illumination scheme. By taking advantage of a broadened bandwidth illumination, the proposed scheme could open for x-ray microscopy with spatial resolution in the range 150-200 nm at millisecond frame rates. The scheme is readily implemented and is achievable using only standard refractive x-ray lenses, which has the advantage of high efficiency. It also maximizes the transmission and removes the spatial filtering effects associated with absorption in x-ray lenses.

  2. Chicago aberration correction work

    Energy Technology Data Exchange (ETDEWEB)

    Beck, V.D., E-mail: vnlbeck@earthlink.net [1 Hobby Drive, Ridgefield, CT 06877-01922 (United States)

    2012-12-15

    The author describes from his personal involvement the many improvements to electron microscopy Albert Crewe and his group brought by minimizing the effects of aberrations. The Butler gun was developed to minimize aperture aberrations in a field emission electron gun. In the 1960s, Crewe anticipated using a spherical aberration corrector based on Scherzer's design. Since the tolerances could not be met mechanically, a method of moving the center of the octopoles electrically was developed by adding lower order multipole fields. Because the corrector was located about 15 cm ahead of the objective lens, combination aberrations would arise with the objective lens. This fifth order aberration would then limit the aperture of the microscope. The transformation of the off axis aberration coefficients of a round lens was developed and a means to cancel anisotropic coma was developed. A new method of generating negative spherical aberration was invented using the combination aberrations of hexapoles. Extensions of this technique to higher order aberrations were developed. An electrostatic electron mirror was invented, which allows the cancellation of primary spherical aberration and first order chromatic aberration. A reduction of chromatic aberration by two orders of magnitude was demonstrated using such a system. -- Highlights: Black-Right-Pointing-Pointer Crewe and his group made significant advances in aberration correction and reduction. Black-Right-Pointing-Pointer A deeper understanding of the quadrupole octopole corrector was developed. Black-Right-Pointing-Pointer A scheme to correct spherical aberration using hexapoles was developed. Black-Right-Pointing-Pointer Chromatic aberration was corrected using a uniform field mirror.

  3. Chromatic aberration-corrected tilt series transmission electron microscopy of nanoparticles in a whole mount macrophage cell.

    Science.gov (United States)

    Baudoin, Jean-Pierre; Jinschek, Joerg R; Boothroyd, Chris B; Dunin-Borkowski, Rafal E; de Jonge, Niels

    2013-08-01

    Transmission electron microscopy (TEM) in combination with electron tomography is widely used to obtain nanometer scale three-dimensional (3D) structural information about biological samples. However, studies of whole eukaryotic cells are limited in resolution and/or contrast on account of the effect of chromatic aberration of the TEM objective lens on electrons that have been scattered inelastically in the specimen. As a result, 3D information is usually obtained from sections and not from whole cells. Here, we use chromatic aberration-corrected TEM to record bright-field TEM images of nanoparticles in a whole mount macrophage cell. Tilt series of images are used to generate electron tomograms, which are analyzed to assess the spatial resolution that can be achieved for different vertical positions in the specimen. The uptake of gold nanoparticles coated with low-density lipoprotein (LDL) is studied. The LDL is found to assemble in clusters. The clusters contain nanoparticles taken up on different days, which are joined without mixing their nanoparticle cargo.

  4. Deconvolution and chromatic aberration corrections in quantifying colocalization of a transcription factor in three-dimensional cellular space.

    Science.gov (United States)

    Abraham, Thomas; Allan, Sarah E; Levings, Megan K

    2010-08-01

    with DNA molecules. In conclusion, our studies clearly demonstrate the importance of PSF measurements, chromatic aberration corrections followed by deconvolution in the accurate determination of transcription factors in the 3D cellular space. The reported imaging and processing methods can be a practical guide for quantitative fluorescence imaging of similar cellular systems and can provide a basis for further development.

  5. Atomic resolution imaging of YAlO3: Ce in the chromatic and spherical aberration corrected PICO electron microscope.

    Science.gov (United States)

    Jin, Lei; Barthel, Juri; Jia, Chun-Lin; Urban, Knut W

    2017-01-31

    The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm. We demonstrate that such a resolution can be achieved in practice at 200kV. Diffractograms of images of gold nanoparticles on amorphous carbon demonstrate corresponding information transfer. The Y atom pairs in [010] oriented yttrium orthoaluminate are successfully imaged together with the Al and the O atoms. Although the 57 pm pair separation is well demonstrated separations between 55 pm and 80 pm are measured. This observation is tentatively attributed to structural relaxations and surface reconstruction in the very thin samples used. Quantification of the resolution limiting effective image spread is achieved based on an absolute match between experimental and simulated image intensity distributions.

  6. Letter: A method for the chromatic aberration correction of a laser time of-flight mass analyzer.

    Science.gov (United States)

    Sysoeva, Elizaveta A; Sysoev, Alexander A

    2016-01-01

    The new ion-optical system of the laser time-of-flight (TOF) mass spectrometer on the basis of two tandem wedge-shape reflectors has been offered and implemented. A new method of correcting chromatic aberration by the ion energy was proposed that used a wire electrode unit with adjustable potentials. This unit allows one to adjust the local TOF of the ions in a narrow energy range ± (1-2)% within the total ion packet with an energy spread of ± 20%. The method reduces the duration of the ion packets by up to 1.5ns, which enables us to obtain the restriction of resolution at a level not worse than R ~ 10500 for a TOF ~35 µs. The aim of the project is to increase the separation of isobaric ions to improve the limit of detection of the laser TOF-MS for the analysis of high-purity samples.

  7. Atom lens without chromatic aberrations

    CERN Document Server

    Efremov, Maxim A; Schleich, Wolfgang P

    2012-01-01

    We propose a lens for atoms with reduced chromatic aberrations and calculate its focal length and spot size. In our scheme a two-level atom interacts with a near-resonant standing light wave formed by two running waves of slightly different wave vectors, and a far-detuned running wave propagating perpendicular to the standing wave. We show that within the Raman-Nath approximation and for an adiabatically slow atom-light interaction, the phase acquired by the atom is independent of the incident atomic velocity.

  8. Wide-angle chromatic aberration corrector for the human eye.

    Science.gov (United States)

    Benny, Yael; Manzanera, Silvestre; Prieto, Pedro M; Ribak, Erez N; Artal, Pablo

    2007-06-01

    The human eye is affected by large chromatic aberration. This may limit vision and makes it difficult to see fine retinal details in ophthalmoscopy. We designed and built a two-triplet system for correcting the average longitudinal chromatic aberration of the eye while keeping a reasonably wide field of view. Measurements in real eyes were conducted to examine the level and optical quality of the correction. We also performed some tests to evaluate the effect of the corrector on visual performance.

  9. Chromatic aberration measurement for transmission interferometric testing.

    Science.gov (United States)

    Seong, Kibyung; Greivenkamp, John E

    2008-12-10

    A method of chromatic aberration measurement is described based on the transmitted wavefront of an optical element obtained from a Mach-Zehnder interferometer. The chromatic aberration is derived from transmitted wavefronts measured at five different wavelengths. Reverse ray tracing is used to remove induced aberrations associated with the interferometer from the measurement. In the interferometer, the wavefront transmitted through the sample is tested against a plano reference, allowing for the absolute determination of the wavefront radius of curvature. The chromatic aberrations of a singlet and a doublet have been measured.

  10. Aberration Correction in Electron Microscopy

    CERN Document Server

    Rose, Harald H

    2005-01-01

    The resolution of conventional electron microscopes is limited by spherical and chromatic aberrations. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer theorem). Multipole correctors and electron mirrros have been designed and built, which compensate for these aberrations. The principles of correction will be demonstrated for the tetrode mirror, the quadrupole-octopole corrector and the hexapole corrector. Electron mirrors require a magnetic beam separator free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the objective lens. The hexapole corrector has the most simple structure yet eliminates only the spherical aberration, whereas the mirror and the quadrupole-octopole corrector are able to correct for both aberrations. Chromatic correction is achieved in the latter corrector by cossed electric and magnetic quadrupoles acting as first-order Wien filters. Micrographs obtaine...

  11. Measuring chromatic aberrations in imaging systems using plasmonic nanoparticles

    Science.gov (United States)

    Gennaro, Sylvain D.; Roschuk, Tyler R.; Maier, Stefan A.; Oulton, Rupert F.

    2016-04-01

    Chromatic aberration in optical systems arises from the wavelength dependence of a glass's refractive index. Polychromatic rays incident upon an optical surface are refracted at slightly different angles and in traversing an optical system follow distinct paths creating images displaced according to color. Although arising from dispersion, it manifests as a spatial distortion correctable only with compound lenses with multiple glasses and accumulates in complicated imaging systems. While chromatic aberration is measured with interferometry, simple methods are attractive for their ease of use and low cost. In this letter we retrieve the longitudinal chromatic focal shift of high numerical aperture (NA) microscope objectives from the extinction spectra of metallic nanoparticles within the focal plane. The method is accurate for high NA objectives with apochromatic correction, and enables rapid assessment of the chromatic aberration of any complete microscopy systems, since it is straightforward to implement

  12. Chicago aberration correction work.

    Science.gov (United States)

    Beck, V D

    2012-12-01

    The author describes from his personal involvement the many improvements to electron microscopy Albert Crewe and his group brought by minimizing the effects of aberrations. The Butler gun was developed to minimize aperture aberrations in a field emission electron gun. In the 1960s, Crewe anticipated using a spherical aberration corrector based on Scherzer's design. Since the tolerances could not be met mechanically, a method of moving the center of the octopoles electrically was developed by adding lower order multipole fields. Because the corrector was located about 15 cm ahead of the objective lens, combination aberrations would arise with the objective lens. This fifth order aberration would then limit the aperture of the microscope. The transformation of the off axis aberration coefficients of a round lens was developed and a means to cancel anisotropic coma was developed. A new method of generating negative spherical aberration was invented using the combination aberrations of hexapoles. Extensions of this technique to higher order aberrations were developed. An electrostatic electron mirror was invented, which allows the cancellation of primary spherical aberration and first order chromatic aberration. A reduction of chromatic aberration by two orders of magnitude was demonstrated using such a system.

  13. Anti-forensics of chromatic aberration

    Science.gov (United States)

    Mayer, Owen; Stamm, Matthew C.

    2015-03-01

    Over the past decade, a number of information forensic techniques have been developed to identify digital image manipulation and falsification. Recent research has shown, however, that an intelligent forger can use anti-forensic countermeasures to disguise their forgeries. In this paper, an anti-forensic technique is proposed to falsify the lateral chromatic aberration present in a digital image. Lateral chromatic aberration corresponds to the relative contraction or expansion between an image's color channels that occurs due to a lens's inability to focus all wavelengths of light on the same point. Previous work has used localized inconsistencies in an image's chromatic aberration to expose cut-and-paste image forgeries. The anti-forensic technique presented in this paper operates by estimating the expected lateral chromatic aberration at an image location, then removing deviations from this estimate caused by tampering or falsification. Experimental results are presented that demonstrate that our anti-forensic technique can be used to effectively disguise evidence of an image forgery.

  14. Measurement of chromatic aberration in STEM and SCEM by coherent convergent beam electron diffraction.

    Science.gov (United States)

    Zheng, C L; Etheridge, J

    2013-02-01

    A simple method is described for the accurate and precise measurement of chromatic aberration under electron-optical conditions pertinent to scanning transmission electron microscopy (STEM) and scanning confocal electron microscopy (SCEM). The method requires only the measurement of distances in a coherent CBED pattern and knowledge of the electron wavelength and the lattice spacing of a calibration specimen. The chromatic aberration of a spherical-aberration corrected 300 kV thermal field emission TEM is measured in STEM and SCEM operating modes and under different condenser lens settings. The effect of the measured chromatic aberrations on the 3 dimensional intensity distribution of the electron probe is also considered.

  15. Calibration and removal of lateral chromatic aberration in images

    OpenAIRE

    Mallon, John; Whelan, Paul F.

    2007-01-01

    This paper addresses the problem of compensating for lateral chromatic aberration in digital images through colour plane realignment. Two main contributions are made: the derivation of a model for lateral chromatic aberration in images, and the subsequent calibration of this model from a single view of a chess pattern. These advances lead to a practical and accurate alternative for the compensation of lateral chromatic aberrations. Experimental results validate the proposed models and calibra...

  16. Filtering chromatic aberration for wide acceptance angle electrostatic lenses.

    Science.gov (United States)

    Fazekas, Ádám; Tóth, László

    2014-07-01

    Chromatic aberration is a major issue for imaging mainly with large acceptance angle electrostatic lenses. Its correction is necessary to take advantage of the outstanding spatial and angular resolution that these lenses provide. We propose a method to eliminate the effect of chromatic aberration on the measured images by determining the impact resulting from higher and lower kinetic energies. Based on a spectral image sequence and a matrix, which describes the transmission function of the lens, a system of linear equations is solved to approximate the 2D spectral intensity distribution of the sample surface. We present the description of our method and preliminary test results, which show significant contrast and image quality improvement. The presented algorithm can also be applied as a software-based energy analyzer.

  17. FCC-ee final focus with chromaticity correction

    CERN Document Server

    Garcia, H; Tomás, R

    2014-01-01

    A 100 km circular electron-positron collider is considered as one of the possible future high energy facilities. In order to achieve a high luminosity, strong beam focusing at the Interaction Point (IP) is used requiring the correction of the chromatic aberrations. In this paper we study preliminary designs of a Final Focus System (FFS) for the FCC-ee collider with chromatic correction. Beam orbit stability and dynamic aperture calculations are also presented.

  18. Aberration Corrected Emittance Exchange

    CERN Document Server

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  19. Removing lateral chromatic aberration in bright field optical microscopy.

    Science.gov (United States)

    Guzmán-Altamirano, Miguel; Gutiérrez-Medina, Braulio

    2015-06-01

    We present an efficient alternative to remove lateral chromatic aberration (LCA) in bright field light microscopy images. Our procedure is based on error calibration using time-sequential acquisition at different wavelengths, and error correction through digital image warping. Measurement of the displacements of fiducial marks in the red and green images relative to blue provide calibration factors that are subsequently used in test images to realign color channels digitally. We demonstrate quantitative improvement in the position and boundaries of objects in target slides and in the color content and morphology of specimens in stained biological samples. Our results show a reduction of LCA content below the 0.1% level.

  20. Measuring chromatic aberrations in imaging systems using plasmonic nano-particles

    CERN Document Server

    Gennaro, Sylvain D; Maier, Stefan A; Oulton, Rupert F

    2015-01-01

    Chromatic aberration in optical systems arises from the wavelength dependence of a glass's refractive index. Polychromatic rays incident upon an optical surface are refracted at slightly different angles and in traversing an optical system follow distinct paths creating images displaced according to color. Although arising from dispersion, it manifests as a spatial distortion correctable only with compound lenses with multiple glasses and accumulates in complicated imaging systems. While chromatic aberration is measured with interferometry, simple methods are attractive for their ease of use and low cost. In this letter we retrieve the longitudinal chromatic focal shift of high numerical aperture (NA) microscope objectives from the extinction spectra of metallic nanoparticles within the focal plane. The method is accurate for high NA objectives with apochromatic correction, and enables rapid assessment of the chromatic aberration of any complete microscopy systems, since it is straightforward to implement

  1. Catadioptric aberration correction in cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  2. Dynamic compensation of chromatic aberration in a programmable diffractive lens.

    Science.gov (United States)

    Millán, María S; Otón, Joaquín; Pérez-Cabré, Elisabet

    2006-10-02

    A proposal to dynamically compensate chromatic aberration of a programmable phase Fresnel lens displayed on a liquid crystal device and working under broadband illumination is presented. It is based on time multiplexing a set of lenses, designed with a common focal length for different wavelengths, and a tunable spectral filter that makes each sublens work almost monochromatically. Both the tunable filter and the sublens displayed by the spatial light modulator are synchronized. The whole set of sublenses are displayed within the integration time of the sensor. As a result the central order focalization has a unique location at the focal plane and it is common for all selected wavelengths. Transversal chromatic aberration of the polychromatic point spread function is reduced by properly adjusting the pupil size of each sublens. Longitudinal chromatic aberration is compensated by making depth of focus curves coincident for the selected wavelengths. Experimental results are in very good agreement with theory.

  3. Low chromatic aberration hexapole for molecular state selection

    Science.gov (United States)

    Ke, Yi; Deng, Xiao-Bing; Hu, Zhong-Kun

    2016-01-01

    In molecular beam state-selection experiments, the electrostatic hexapole acts as an optical lens, imaging molecules from the source to the focus. The molecular longitudinal velocity spread induces the phenomenon of chromatic aberration, which will reduce the state-selection purity. We propose a scheme which can effectively reduce the chromatic aberration by changing the hexapole voltage operating manner. The hexapole is already charged before molecules arrive at the entrance of the hexapole. When molecules are completely inside the hexapole, the voltage is switched off rapidly at an appropriate time. In this manner, faster molecules travel a longer hexapole focusing region than slower molecules. Therefore the focusing positions of molecules with different velocities become close. Numerical trajectory simulations of molecular state selection are carried out, and the results show that this low chromatic aberration hexapole can significantly improve the state purity from 46.2% to 87.0%.

  4. Theoretical estimates of spherical and chromatic aberration in photoemission electron microscopy.

    Science.gov (United States)

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2016-01-01

    We present theoretical estimates of the mean coefficients of spherical and chromatic aberration for low energy photoemission electron microscopy (PEEM). Using simple analytic models, we find that the aberration coefficients depend primarily on the difference between the photon energy and the photoemission threshold, as expected. However, the shape of the photoelectron spectral distribution impacts the coefficients by up to 30%. These estimates should allow more precise correction of aberration in PEEM in experimental situations where the aberration coefficients and precise electron energy distribution cannot be readily measured.

  5. Design of an aberration corrected low-voltage SEM

    NARCIS (Netherlands)

    Aken, R.H. van; Maas, D.J.; Hagen, C.W.; Barth, J.E.; Kruit, P.

    2010-01-01

    The low-voltage foil corrector is a novel type of foil aberration corrector that can correct for both the spherical and chromatic aberration simultaneously. In order to give a realistic example of the capabilities of this corrector, a design for a low-voltage scanning electron microscope with the lo

  6. Measurement of chromatic aberration in STEM and SCEM by coherent convergent beam electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, C.L. [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Etheridge, J., E-mail: joanne.etheridge@monash.edu [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

    2013-02-15

    A simple method is described for the accurate and precise measurement of chromatic aberration under electron-optical conditions pertinent to scanning transmission electron microscopy (STEM) and scanning confocal electron microscopy (SCEM). The method requires only the measurement of distances in a coherent CBED pattern and knowledge of the electron wavelength and the lattice spacing of a calibration specimen. The chromatic aberration of a spherical-aberration corrected 300 kV thermal field emission TEM is measured in STEM and SCEM operating modes and under different condenser lens settings. The effect of the measured chromatic aberrations on the 3 dimensional intensity distribution of the electron probe is also considered. - Highlights: ► A method is presented to measure chromatic aberration (C{sub c}) using coherent CBED. ► The C{sub c} of the probe and imaging lens systems in STEM and SCEM modes is measured in a C{sub 3}-corrected S/TEM. ► The effect of the measured C{sub c} on the depth resolution in STEM is simulated for different energy spreads.

  7. Adaptive aberration correction using a triode hyperbolic electron mirror.

    Science.gov (United States)

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2011-01-01

    A converging electron mirror can be used to compensate spherical and chromatic aberrations in an electron microscope. This paper presents an analytical solution to a novel triode (three electrode) hyperbolic mirror as an improvement to the well-known diode (two electrode) hyperbolic mirror for aberration correction. A weakness of the diode mirror is a lack of flexibility in changing the chromatic and spherical aberration coefficients independently without changes in the mirror geometry. In order to remove this limitation, a third electrode can be added. We calculate the optical properties of the resulting triode mirror analytically on the basis of a simple model field distribution. We present the optical properties-the object/image distance, z(0), and the coefficients of spherical and chromatic aberration, C(s) and C(c), of both mirror types from an analysis of electron trajectories in the mirror field. From this analysis, we demonstrate that while the properties of both designs are similar, the additional parameters in the triode mirror improve the range of aberration that can be corrected. The triode mirror is also able to provide a dynamic adjustment range of chromatic aberration for fixed spherical aberration and focal length, or any permutation of these three parameters. While the dynamic range depends on the values of aberration correction needed, a nominal 10% tuning range is possible for most configurations accompanied by less than 1% change in the other two properties.

  8. Refractive and diffractive neutron optics with reduced chromatic aberration

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Poulsen, Henning Friis; Bentley, P.M.

    2014-01-01

    by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness...

  9. Breaking the spherical and chromatic aberration barrier in transmission electron microscopy.

    Science.gov (United States)

    Freitag, B; Kujawa, S; Mul, P M; Ringnalda, J; Tiemeijer, P C

    2005-02-01

    Since the invention of transmission electron microscopy (TEM) in 1932 (Z. Physik 78 (1932) 318) engineering improvements have advanced system resolutions to levels that are now limited only by the two fundamental aberrations of electron lenses; spherical and chromatic aberration (Z. Phys. 101 (1936) 593). Since both aberrations scale with the dimensions of the lens, research resolution requirements are pushing the designs to lenses with only a few mm space in the pole-piece gap for the specimen. This is in conflict with the demand for more and more space at the specimen, necessary in order to enable novel techniques in TEM, such as He-cooled cryo electron microscopy, 3D-reconstruction through tomography (Science 302 (2003) 1396) TEM in gaseous environments, or in situ experiments (Nature 427 (2004) 426). All these techniques will only be able to achieve Angstrom resolution when the aberration barriers have been overcome. The spherical aberration barrier has recently been broken by introducing spherical aberration correctors (Nature 392 (1998) 392, 418 (2002) 617), but the correction of the remaining chromatic aberrations have proved to be too difficult for the present state of technology (Optik 57 (1980) 73). Here we present an alternative and successful method to eliminate the chromatic blur, which consists of monochromating the TEM beam (Inst. Phys. Conf. Ser. 161 (1999) 191). We show directly interpretable resolutions well below 1A for the first time, which is significantly better than any TEM operating at 200 KV has reached before.

  10. Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels

    Energy Technology Data Exchange (ETDEWEB)

    J.A. Maloney, B. Erdelyi, A. Afanaciev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov

    2011-03-01

    Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

  11. Chromatically Corrected Imaging Systems for Charged-Particle Radiography

    CERN Document Server

    Blind, Barbara

    2005-01-01

    In proton radiography, imaging with systems consisting of quadrupole magnets is an established technique for viewing the material distribution and composition of objects, either statically or during fast events such as explosions. With the most favorable magnet configuration, the -I lens, chromatic aberrations generally dominate the image blur. Image resolution can be improved, and largely decoupled from the input-beam parameters, by using a second-order achromatic bend with some additional higher-order aberration correction. The aberration-correction approach is discussed. For a given resolution, such a bend allows use of much lower-energy imaging particles than a -I lens. Each bend design represents a set of equivalent systems; an 800-MeV proton design and its equivalent 40-MeV electron system are presented. The electron system is useful for imaging small objects. Magnet errors in the achromatic bends must be tightly controlled to preserve image quality, but not beyond feasibility of present technology. Sys...

  12. Longitudinal chromatic aberration of the human infant eye.

    Science.gov (United States)

    Wang, Jingyun; Candy, T Rowan; Teel, Danielle F W; Jacobs, Robert J

    2008-09-01

    Although the longitudinal chromatic aberration (LCA) of the adult eye has been studied, there are no data collected from the human infant eye. A chromatic retinoscope was used to measure cyclopleged infant and adult refractions with four pseudomonochromatic sources (centered at 472, 538, 589, and 652 nm) and with polychromatic light. The LCA of the infant eyes between 472 and 652 nm was a factor of 1.7 greater than the LCA found in the adult group: infant mean=1.62 D, SD+/- 0.14 D; adult mean=0.96 D, SD+/- 0.17 D. The elevated level of LCA in infant eyes is consistent with the greater optical power of the immature eye and indicates similar chromatic dispersion in infant and adult eyes. The implications for visual performance, defocus detection, and measurement of refraction are discussed.

  13. Eliminating chromatic aberration in Gauss-type lens design using a novel genetic algorithm.

    Science.gov (United States)

    Fang, Yi-Chin; Tsai, Chen-Mu; Macdonald, John; Pai, Yang-Chieh

    2007-05-01

    Two different types of Gauss lens design, which effectively eliminate primary chromatic aberration, are presented using an efficient genetic algorithm (GA). The current GA has to deal with too many targets in optical global optimization so that the performance is not much improved. Generally speaking, achromatic aberrations have a great relationship with variable glass sets for all elements. For optics whose design is roughly convergent, glass sets for optics will play a significant role in axial and lateral color aberration. Therefore better results might be derived from the optimal process of eliminating achromatic aberration, which could be carried out by finding feasible glass sets in advance. As an alternative, we propose a new optimization process by using a GA and involving theories of geometrical optics in order to select the best optical glass combination. Two Gauss-type lens designs are employed in this research. First, a telephoto lens design is sensitive to axial aberration because of its long focal length, and second, a wide-angle Gauss design is complicated by lateral color aberration at the extreme corners because Gauss design is well known not to deal well with wide-angle problems. Without numbers of higher chief rays passing the element, it is difficult to correct lateral color aberration altogether for the Gauss design. The results and conclusions show that the attempts to eliminate primary chromatic aberrations were successful.

  14. Construction of special eye models for investigation of chromatic and higher-order aberrations of eyes.

    Science.gov (United States)

    Zhai, Yi; Wang, Yan; Wang, Zhaoqi; Liu, Yongji; Zhang, Lin; He, Yuanqing; Chang, Shengjiang

    2014-01-01

    An achromatic element eliminating only longitudinal chromatic aberration (LCA) while maintaining transverse chromatic aberration (TCA) is established for the eye model, which involves the angle formed by the visual and optical axis. To investigate the impacts of higher-order aberrations on vision, the actual data of higher-order aberrations of human eyes with three typical levels are introduced into the eye model along visual axis. Moreover, three kinds of individual eye models are established to investigate the impacts of higher-order aberrations, chromatic aberration (LCA+TCA), LCA and TCA on vision under the photopic condition, respectively. Results show that for most human eyes, the impact of chromatic aberration on vision is much stronger than that of higher-order aberrations, and the impact of LCA in chromatic aberration dominates. The impact of TCA is approximately equal to that of normal level higher-order aberrations and it can be ignored when LCA exists.

  15. Chromatic aberration control for tunable all-silicone membrane microlenses.

    Science.gov (United States)

    Waibel, Philipp; Mader, Daniel; Liebetraut, Peter; Zappe, Hans; Seifert, Andreas

    2011-09-12

    Tunable multi-chamber microfluidic membrane microlenses with achromaticity over a given focal length range are demonstrated. In analogy to a fixed-focus achromatic doublet lens, the multi-lens system is based on a stack of microfluidic cavities filled with optically optimized liquids with precisely defined refractive index and Abbe number, and these are independently pneumatically actuated. The membranes separating the cavities form the refractive optical surfaces, and the curvatures as a function of pressure are calculated using a mechanical model for deformation of flexible plates. The results are combined with optical ray tracing simulations of the multi-lens system to yield chromatic aberration behavior, which is verified experimentally. A focal length tuning range of 5-40 mm and reduction in chromatic aberration of over 30% is demonstrated, limited by the availability of optical fluids.

  16. Manipulation of spatiotemporal photon distribution via chromatic aberration.

    Science.gov (United States)

    Li, Yuelin; Chemerisov, Sergey

    2008-09-01

    We demonstrate a spatiotemporal laser-pulse-shaping scheme that exploits the chromatic aberration in a dispersive lens. This normally harmful effect transforms the phase modulation into a beam-size modulation at the focal plane. In combination with the intricate diffraction effect via beam apodization, this method provides a spatiotemporal control of photon distribution with an accuracy of diffraction limit on a time scale of femtoseconds.

  17. The correction of electron lens aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hawkes, P.W., E-mail: peter.hawkes@cemes.fr

    2015-09-15

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. - Highlights: • Geometrical aberration correction. • Chromatic aberration correction. • 50 pm resolution. • High-resolution electron energy-loss spectroscopy. • Extensive bibliographies.

  18. Chromatic variation of aberration: the role of induced aberrations and raytrace direction

    Science.gov (United States)

    Berner, A.; Nobis, T.; Shafer, D.; Gross, H.

    2015-09-01

    The design and optimization process of an optical system contains several first order steps. The definition of the appropriate lens type and the fixation of the raytrace direction are some of them. The latter can be understood as a hidden assumption rather than an aware design step. This is usually followed by the determination of the paraxial lens layout calculated for the primary wavelength. It is obvious, that for this primary wavelength the paraxial calculations are independent of raytrace direction. Today, most of the lens designs are specified not to work only for one wavelength, but in a certain wavelength range. Considering such rays of other wavelengths, one can observe that depending on the direction there will already occur differences in the first order chromatic aberrations and additionally in the chromatic variation of the third-order aberrations. The reason for this effect are induced aberrations emerging from one surface to the following surfaces by perturbed ray heights and ray angles. It can be shown, that the total amount of surface-resolved first order chromatic aberrations and the chromatic variation of the five primary aberrations can be split into an intrinsic part and an induced part. The intrinsic part is independent of the raytrace direction whereas the induced part is not.

  19. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  20. Miniaturized modules for light sheet microscopy with low chromatic aberration.

    Science.gov (United States)

    Bruns, T; Bauer, M; Bruns, S; Meyer, H; Kubin, D; Schneckenburger, H

    2016-12-01

    Two miniaturized fibre-coupled modules for light sheet-based microscopy are described and compared with respect to image quality, chromatic aberration and beam alignment. Whereas in one module the light sheet is created by an achromatic cylindrical lens, reflection by a spherical mirror and concomitant astigmatic distortion are used to create the light sheet in the second module. Test experiments with fluorescent dyes in solution and multicellular tumour spheroids are reported, and some details on construction are given for both systems. Both modules are optimized for imaging individual cell layers of 3D biological samples and can be adapted to fit commercial microscopes.

  1. Chromatic aberration and the roles of double-opponent and color-luminance neurons in color vision

    NARCIS (Netherlands)

    Vladusich, Tony

    2007-01-01

    How does the visual cortex encode color? I summarize a theory in which cortical double-opponent color neurons perform a role in color constancy and a complementary set of color-luminance neurons function to selectively correct for color fringes induced by chromatic aberration in the eye. The theory

  2. Double aberration correction in a low-energy electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Th., E-mail: schmidtt@fhi-berlin.mpg.de [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 6-8, D-14195 Berlin (Germany); Universitaet Wuerzburg, Experimentelle Physik II, Am Hubland, D-97074 Wuerzburg (Germany); Marchetto, H.; Levesque, P.L. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 6-8, D-14195 Berlin (Germany); Groh, U.; Maier, F. [Universitaet Wuerzburg, Experimentelle Physik II, Am Hubland, D-97074 Wuerzburg (Germany); Preikszas, D. [Technische Universitaet Darmstadt, Angewandte Physik, Hochschulstrasse 6, D-64289 Darmstadt (Germany); Carl Zeiss NTS GmbH, Carl-Zeiss-Strasse 56, D-73447 Oberkochen (Germany); Hartel, P.; Spehr, R. [Technische Universitaet Darmstadt, Angewandte Physik, Hochschulstrasse 6, D-64289 Darmstadt (Germany); Lilienkamp, G. [Technische Universitaet Clausthal, Physikalisches Institut, Leibnizstrasse 4, D-38678 (Germany); Engel, W. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 6-8, D-14195 Berlin (Germany); Fink, R. [Universitaet Erlangen-Nuernberg, Physikalische Chemie II, Egerlandstrasse 3, D-91058 Erlangen (Germany); Bauer, E. [Technische Universitaet Clausthal, Physikalisches Institut, Leibnizstrasse 4, D-38678 (Germany); Arizona State University, Department of Physics, Tempe, AZ 85287 (United States); Rose, H. [Technische Universitaet Darmstadt, Angewandte Physik, Hochschulstrasse 6, D-64289 Darmstadt (Germany); Umbach, E. [Universitaet Wuerzburg, Experimentelle Physik II, Am Hubland, D-97074 Wuerzburg (Germany); Freund, H.-J. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 6-8, D-14195 Berlin (Germany)

    2010-10-15

    The lateral resolution of a surface sensitive low-energy electron microscope (LEEM) has been improved below 4 nm for the first time. This breakthrough has only been possible by simultaneously correcting the unavoidable spherical and chromatic aberrations of the lens system. We present an experimental criterion to quantify the aberration correction and to optimize the electron optical system. The obtained lateral resolution of 2.6 nm in LEEM enables the first surface sensitive, electron microscopic observation of the herringbone reconstruction on the Au(1 1 1) surface.

  3. Differential algebraic method for arbitrary order curvilinear-axis combined geometric-chromatic aberration analysis

    CERN Document Server

    Cheng Min; Lu Yi Long; Yao Zhen Hua

    2003-01-01

    The principle of differential algebra is applied to analyse and calculate arbitrary order curvilinear-axis combined geometric-chromatic aberrations of electron optical systems. Expressions of differential algebraic form of high order combined aberrations are obtained and arbitrary order combined aberrations can be calculated numerically. As an example, a typical wide electron beam focusing system with curved optical axes named magnetic immersion lens has been studied. All the second-order and third-order combined geometric-chromatic aberrations of the lens have been calculated, and the patterns of the corresponding geometric aberrations and combined aberrations have been given as well.

  4. Eye-tracking technology for real-time monitoring of transverse chromatic aberration

    Science.gov (United States)

    Privitera, Claudio M.; Sabesan, Ramkumar; Winter, Simon; Tiruveedhula, Pavan; Roorda, Austin

    2017-01-01

    Objective measurements of transverse chromatic aberration (TCA) between two or more wavelengths with an adaptive optics scanning laser ophthalmoscope (AOSLO) are very accurate, but frequent measurements are impractical in many experimental settings. Here, we demonstrate a pupil-tracker that can accurately measure relative changes in TCA that are caused by small shifts in the pupil relative to the AOSLO imaging beam. Corrections for TCA caused by these shifts improve the measurement of TCA as a function of eccentricity, revealing a strong linear relationship. We propose that pupil tracking be integrated into AOSLO systems where robust and unobtrusive control of TCA is required. PMID:27082330

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

    Science.gov (United States)

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

    2016-05-01

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

  6. Photographic simulation of off-axis blurring due to chromatic aberration in spectacle lenses.

    Science.gov (United States)

    Doroslovački, Pavle; Guyton, David L

    2015-02-01

    Spectacle lens materials of high refractive index (nd) tend to have high chromatic dispersion (low Abbé number [V]), which may contribute to visual blurring with oblique viewing. A patient who noted off-axis blurring with new high-refractive-index spectacle lenses prompted us to do a photographic simulation of the off-axis aberrations in 3 readily available spectacle lens materials, CR-39 (nd = 1.50), polyurethane (nd = 1.60), and polycarbonate (nd = 1.59). Both chromatic and monochromatic aberrations were found to cause off-axis image degradation. Chromatic aberration was more prominent in the higher-index materials (especially polycarbonate), whereas the lower-index CR-39 had more astigmatism of oblique incidence. It is important to consider off-axis aberrations when a patient complains of otherwise unexplained blurred vision with a new pair of spectacle lenses, especially given the increasing promotion of high-refractive-index materials with high chromatic dispersion.

  7. Reverse chromatic aberration and its numerical optimization in a metamaterial lens.

    Science.gov (United States)

    Capecchi, William J; Behdad, Nader; Volpe, Francesco A

    2012-04-09

    In planar metamaterial lenses, the focal point moves with the frequency. Here it is shown numerically that this movement can be controlled by properly engineering the dimensions of the metamaterial-based phase shifters that constitute the lens. In particular, such lenses can be designed to exhibit unusual chromatic aberration with the focal length increasing, rather than decreasing, with the frequency. It is proposed that such an artificial "reverse" chromatic aberration may optimize the transverse resolution of millimeter wave diagnostics of plasmas and be useful in compensating for the natural "ordinary" chromatic aberration of other components in an optical system. More generally, optimized chromatic aberration will allow for simultaneous focusing of several objects located at different distances and emitting or reflecting at different frequencies.

  8. Reverse Chromatic Aberration and its Numerical Optimization in a Metamaterial Lens

    CERN Document Server

    Capecchi, W J; Volpe, F A; 10.1364/OE.20.008761

    2013-01-01

    In planar metamaterial lenses, the focal point moves with the frequency. Here it is shown numerically that this movement can be controlled by properly engineering the dimensions of the metamaterial-based phase shifters that constitute the lens. In particular, such lenses can be designed to exhibit unusual chromatic aberration with the focal length increasing, rather than decreasing, with the frequency. It is proposed that such an artificial "reverse" chromatic aberration may optimize the transverse resolution of millimeter wave diagnostics of plasmas and be useful in compensating for the natural "ordinary" chromatic aberration of other components in an optical system. More generally, optimized chromatic aberration will allow to simultaneously focus on several objects located at different distances and emitting or reflecting at different frequencies.

  9. Refractive and diffractive neutron optics with reduced chromatic aberration

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, S.O., E-mail: stefan.poulsen@northwestern.edu [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Poulsen, H.F. [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Bentley, P.M. [European Spallation Source ESS AB, Box 176, 221 00 Lund (Sweden)

    2014-12-11

    Thermal neutron beams are an indispensable tool in physics research. The spatial and the temporal resolution attainable in experiments are dependent on the flux and collimation of the neutron beam which remain relatively poor, even for modern neutron sources. These difficulties may be mitigated by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams.

  10. Perceived no reference image quality measurement for chromatic aberration

    Science.gov (United States)

    Lamb, Anupama B.; Khambete, Madhuri

    2016-03-01

    Today there is need for no reference (NR) objective perceived image quality measurement techniques as conducting subjective experiments and making reference image available is a very difficult task. Very few NR perceived image quality measurement algorithms are available for color distortions like chromatic aberration (CA), color quantization with dither, and color saturation. We proposed NR image quality assessment (NR-IQA) algorithms for images distorted with CA. CA is mostly observed in images taken with digital cameras, having higher sensor resolution with inexpensive lenses. We compared our metric performance with two state-of-the-art NR blur techniques, one full reference IQA technique and three general-purpose NR-IQA techniques, although they are not tailored for CA. We used a CA dataset in the TID-2013 color image database to evaluate performance. Proposed algorithms give comparable performance with state-of-the-art techniques in terms of performance parameters and outperform them in terms of monotonicity and computational complexity. We have also discovered that the proposed CA algorithm best predicts perceived image quality of images distorted with realistic CA.

  11. Reverse Chromatic Aberration and its Numerical Optimization in a Metamaterial Lens

    OpenAIRE

    Capecchi, W. J.; Behdad, N.; Volpe, F. A.

    2013-01-01

    In planar metamaterial lenses, the focal point moves with the frequency. Here it is shown numerically that this movement can be controlled by properly engineering the dimensions of the metamaterial-based phase shifters that constitute the lens. In particular, such lenses can be designed to exhibit unusual chromatic aberration with the focal length increasing, rather than decreasing, with the frequency. It is proposed that such an artificial "reverse" chromatic aberration may optimize the tran...

  12. Effects of various storage conditions and alterations of antioxidant contents on chromatic aberration of hydroquinone ointment.

    Science.gov (United States)

    Matsubayashi, Teruhisa; Sakaeda, Toshiyuki; Kita, Tomoko; Nakamura, Tsutomu; Kakumoto, Mikio; Funasaka, Yoko; Ichihashi, Masamitsu; Fujita, Takuya; Kamiyama, Fumio; Yamamoto, Akira; Nordlund, James J; Kaneko, Masafumi; Iida, Akira; Okumura, Katsuhiko

    2003-01-01

    Ointments of the skin depigmentation agent hydroquinone (HQ) have been prepared by extemporaneous nonsterile compounding in our hospital. The HQ ointments were highly effective in the treatment of various types of skin pigmentations; however, various problems have emerged including chromatic aberration of the ointments, a relatively large variability of efficacy, and mild side effects. Chromatic aberration is expected to induce non-compliance, and this may be the reason for the relatively large variability in efficacy. In this paper, the effects of various storage conditions on the chromatic aberration and HQ content of HQ ointments were evaluated, and it was suggested that the chromatic aberration was accelerated by exposure to high temperature, air and light, although these had no effect on the HQ content. In addition, various types of HQ ointments were prepared to find a formulation to minimize chromatic aberration, and it was found that the concentrations of antioxidants, Na(2)SO(3) and L(+)-ascorbic acid (AsA), seemed to be too high, and that the protective effect of AsA on chromatic aberration was mainly due to its acidifying effect.

  13. Effect of Lossy JPEG Compression of an Image with Chromatic Aberrations on Target Measurement Accuracy

    Science.gov (United States)

    Matsuoka, R.

    2014-05-01

    This paper reports an experiment conducted to investigate the effect of lossy JPEG compression of an image with chromatic aberrations on the measurement accuracy of target center by the intensity-weighted centroid method. I utilized six images shooting a white sheet with 30 by 20 black filled circles in the experiment. The images were acquired by a digital camera Canon EOS 20D. The image data were compressed by using two compression parameter sets of a downsampling ratio, a quantization table and a Huffman code table utilized in EOS 20D. The experiment results clearly indicate that lossy JPEG compression of an image with chromatic aberrations would produce a significant effect on measurement accuracy of target center by the intensity-weighted centroid method. The maximum displacements of red, green and blue components caused by lossy JPEG compression were 0.20, 0.09, and 0.20 pixels respectively. The results also suggest that the downsampling of the chrominance components Cb and Cr in lossy JPEG compression would produce displacements between uncompressed image data and compressed image data. In conclusion, since the author consider that it would be unable to correct displacements caused by lossy JPEG compression, the author would recommend that lossy JPEG compression before recording an image in a digital camera should not be executed in case of highly precise image measurement by using color images acquired by a non-metric digital camera.

  14. Chick eyes compensate for chromatic simulations of hyperopic and myopic defocus: Evidence that the eye uses longitudinal chromatic aberration to guide eye-growth

    OpenAIRE

    Rucker, Frances J.; Wallman, Josh

    2009-01-01

    Longitudinal chromatic aberration (LCA) causes short wavelengths to be focused in front of long wavelengths. This chromatic signal is evidently used to guide ocular accommodation. We asked whether chick eyes exposed to static gratings simulating the chromatic effects of myopic or hyperopic defocus would “compensate” for the simulated defocus.

  15. Chromatic aberration and the roles of double-opponent and color-luminance neurons in color vision.

    Science.gov (United States)

    Vladusich, Tony

    2007-03-01

    How does the visual cortex encode color? I summarize a theory in which cortical double-opponent color neurons perform a role in color constancy and a complementary set of color-luminance neurons function to selectively correct for color fringes induced by chromatic aberration in the eye. The theory may help to resolve an ongoing debate concerning the functional properties of cortical receptive fields involved in color coding.

  16. Influence of ocular chromatic aberration and pupil size on transverse resolution in ophthalmic adaptive optics optical coherence tomography.

    Science.gov (United States)

    Fernández, Enrique; Drexler, Wolfgang

    2005-10-03

    Optical coherence tomography (OCT) enables visualization of the living human retina with unprecedented high axial resolution. The transverse resolution of existing OCT approaches is relatively modest as compared to other retinal imaging techniques. In this context, the use of adaptive optics (AO) to correct for ocular aberrations in combination with OCT has recently been demonstrated to notably increase the transverse resolution of the retinal OCT tomograms. AO is required when imaging is performed through moderate and large pupil sizes. A fundamental difference of OCT as compared to other imaging techniques is the demand of polychromatic light to accomplish high axial resolution. In ophthalmic OCT applications, the performance is therefore also limited by ocular chromatic aberrations. In the current work, the effects of chromatic and monochromatic ocular aberrations on the quality of retinal OCT tomograms, especially concerning transverse resolution, sensitivity and contrast, are theoretically studied and characterized. The repercussion of the chosen spectral bandwidth and pupil size on the final transverse resolution of OCT tomograms is quantitatively examined. It is found that losses in the intensity of OCT images obtained with monochromatic aberration correction can be up to 80 %, using a pupil size of 8 mm diameter in combination with a spectral bandwidth of 120 nm full width at half maximum for AO ultrahigh resolution OCT. The limits to the performance of AO for correction of monochromatic aberrations in OCT are established. The reduction of the detected signal and the resulting transverse resolution caused by chromatic aberration of the human eye is found to be strongly dependent on the employed bandwidth and pupil size. Comparison of theoretical results with experimental findings obtained in living human eyes is also provided.

  17. Effects of ocular transverse chromatic aberration on peripheral word identification.

    Science.gov (United States)

    Yang, Shun-Nan; Tai, Yu-chi; Laukkanen, Hannu; Sheedy, James E

    2011-11-01

    Transverse chromatic aberration (TCA) smears the retinal image of peripheral stimuli. We previously found that TCA significantly reduces the ability to recognize letters presented in the near fovea by degrading image quality and exacerbating crowding effect from adjacent letters. The present study examined whether TCA has a significant effect on near foveal and peripheral word identification, and whether within-word orthographic facilitation interacts with TCA effect to affect word identification. Subjects were briefly presented a 6- to 7-letter word of high or low frequency in each trial. Target words were generated with weak or strong horizontal color fringe to attenuate the TCA in the right periphery and exacerbate it in the left. The center of the target word was 1°, 2°, 4°, and 6° to the left or right of a fixation point. Subject's eye position was monitored with an eye-tracker to ensure proper fixation before target presentation. They were required to report the identity of the target word as soon and accurately as possible. Results show significant effect of color fringe on the latency and accuracy of word recognition, indicating existing TCA effect. Observed TCA effect was more salient in the right periphery, and was affected by word frequency more there. Individuals' subjective preference of color-fringed text was correlated to the TCA effect in the near periphery. Our results suggest that TCA significantly affects peripheral word identification, especially when it is located in the right periphery. Contextual facilitation such as word frequency interacts with TCA to influence the accuracy and latency of word recognition.

  18. Combined influences of chromatic aberration and scattering in depth-resolved two-photon fluorescence endospectroscopy.

    Science.gov (United States)

    Wu, Yicong; Li, Xingde

    2010-10-27

    The influence of chromatic aberration of an objective lens in two-photon fluorescence (TPF) endospectroscopy of scattering media has been systematically investigated through both experiments and numerical simulations. Experiments were carried out on a uniform 3D scattering gelatin phantom embedded with TiO(2) granules (to mimic tissue scattering) and fluorescein-tagged polystyrene beads. It was found that fluorescence spectral intensity and lineshape varied as a function of depth when measured with a gradient-index (GRIN) lens which has severe chromatic aberration. The spectral distortion caused by the chromatic aberration became diminishing as the imaging depth increased. Ray tracing analysis and Monte Carlo simulations were carried out to study the interplay of chromatic aberration and scattering in the depth-resolved TPF spectra. The simulation results suggest that the collected fluorescence signals from deeper layers included more out-of-focus photons that experienced a few or multiple scatterings, which diminish the influence of chromatic aberration on the measured TPF spectra. The simulated collection efficiencies of TPF at different wavelengths and depths can be used to properly recover the true depth-resolved TPF spectra of a relatively uniform scattering medium.

  19. Sorting chromatic sextupoles for easily and effectively correcting second order chromaticity in the Relativistic Heavy Ion Collider

    Energy Technology Data Exchange (ETDEWEB)

    Luo,Y.; Tepikian, S.; Fischer, W.; Robert-Demolaize, G.; Trbojevic, D.

    2009-01-02

    Based on the contributions of the chromatic sextupole families to the half-integer resonance driving terms, we discuss how to sort the chromatic sextupoles in the arcs of the Relativistic Heavy Ion Collider (RHIC) to easily and effectively correct the second order chromaticities. We propose a method with 4 knobs corresponding to 4 pairs of chromatic sextupole families to online correct the second order chromaticities. Numerical simulation justifies this method, showing that this method reduces the unbalance in the correction strengths of sextupole families and avoids the reversal of sextupole polarities. Therefore, this method yields larger dynamic apertures for the proposed RHIC 2009 100GeV polarized proton run lattices.

  20. Numerical analysis of low chromatic aberration of a gradient refractive index rod lens.

    Science.gov (United States)

    Lv, Hao; Liu, Aimei; Yi, Xunong; Li, Qianguang

    2009-01-20

    The oxide compositions (OCs) model is established for discussing the chromatic aberrations of a gradient refractive index rod lens. The chromatic aberrations for Na(+)/Li(+), K(+)/Cs(+), and K(+)/Tl(+) ion exchanges are discussed based on the OC model and the Huggins-Sun-Davis (HSD) model. Theoretical results indicate that the function value mainly depends on base glass properties and the nature of exchanging ion pairs, and rarely depends on the quantity of ion exchange. Experimental results show that the chromatic aberrations using the OC model have smaller errors than with the HSD model. The estimating average errors between the OC model and the HSD model are -0.051, -0.0067, and 0.0047 for the K(+)/Tl(+), Li(+)/Na(+), and K(+)/Cs(+) ion exchanges, respectively.

  1. Chromatic aberration of light focusing in hyperbolic anisotropic metamaterial made of metallic slit array.

    Science.gov (United States)

    Guo, Kai; Liu, Jianlong; Zhang, Yan; Liu, Shutian

    2012-12-17

    The dispersion of a hyperbolic anisotropic metamaterial (HAM) and the chromatic aberration of light focusing in this kind of HAM are studied. The HAM is formed by alternately stacking metal and dielectric layers. The rules of materials and filling factors affecting the optical property of HAM are given. The chromatic aberration of light focusing is demonstrated both theoretically and numerically. By comparing the theory with the simulation results, the factors influencing the focal length, including the heat loss of material and low spatial frequency modes, are discussed. The investigation emphasizes the anomalous properties, such as chromatic aberration and low spatial frequency modes influencing focus position, of HAM compared with that in conventional lens. Based on the analysis, the possibility of using HAM to focus light with two different wavelengths at the same point is studied.

  2. Neural network correction of astrometric chromaticity

    CERN Document Server

    Gai, M

    2005-01-01

    In this paper we deal with the problem of chromaticity, i.e. apparent position variation of stellar images with their spectral distribution, using neural networks to analyse and process astronomical images. The goal is to remove this relevant source of systematic error in the data reduction of high precision astrometric experiments, like Gaia. This task can be accomplished thanks to the capability of neural networks to solve a nonlinear approximation problem, i.e. to construct an hypersurface that approximates a given set of scattered data couples. Images are encoded associating each of them with conveniently chosen moments, evaluated along the y axis. The technique proposed, in the current framework, reduces the initial chromaticity of few milliarcseconds to values of few microarcseconds.

  3. Study on chromatic aberration in a population of Chinese myopic eyes by means of optical design.

    Science.gov (United States)

    He, Yuanqing; Wang, Yan; Wang, Zhaoqi; Fang, Chao; Liu, Yongji; Zhang, Lin; Zheng, Shaolin; Wang, Lu; Chang, Shengjiang

    2013-05-01

    Two kinds of individual eye models, involving and without involving the angle between visual axis and optical axis, are established by means of optical design. We use them to study the properties of the transverse chromatic aberration (TCA) and longitudinal chromatic aberration (LCA) over the visible spectrum. Then the effects of the LCA and TCA on the visual quality of human eyes are evaluated. The statistical averages of TCA and LCA over the visible spectrum for Chinese myopic eyes are obtained. Results show that both TCA and LCA restrict the visual performance, and LCA is more detrimental than TCA.

  4. Modeling and design of a multichannel chromatic aberration compensated imaging system

    Science.gov (United States)

    Belay, Gebirie Y.; Ottevaere, Heidi; Vervaeke, Michael; Van Erps, Jürgen; Thienpont, Hugo

    2015-09-01

    Conventional multichannel imaging systems comprise of many optical channels having similar imaging properties, namely field-of-view (FOV) and angular resolution/magnification. We demonstrated that the different optical channels can be designed such that each optical channel captures a different FOV and angular resolution compared to its neighboring channels. We designed and experimentally demonstrated a three-channel multiresolution imaging system where the first optical channel has the narrowest FOV (7°) and highest angular resolution (0.0096°) and the third optical channel has the widest FOV (80°) and lowest angular resolution (0.078°)1. The second optical channel has intermediate properties. The performance of the demonstrated three-channel imaging system however was affected by chromatic aberrations as it was designed for a single wavelength of 587.6 nm. The first optical channel was largely influenced by longitudinal chromatic aberration while the third channel by lateral chromatic aberration. Therefore, we have replaced the aspherical refractive lenses by hybrid lenses, which contain diffractive structures on top of their refractive surfaces, in the three-channel multiresolution imaging system to reduce its chromatic aberrations. The performance of the three channels with hybrid lenses is compared with those of the corresponding channels without hybrid lenses. The longitudinal color aberration of the first optical channel has been reduced from 1.7 mm to 0.2 mm; whereas the lateral color aberration of the third optical channel has been reduced from 250 μm to 14 μm. In conclusion, the hybrid lenses have reduced the chromatic aberrations of the three channels and extended the operating spectral range of the imaging system in the visible wavelength range.

  5. Compensation for longitudinal chromatic aberration in the eye of the firefly squid, Watasenia scintillans.

    Science.gov (United States)

    Kröger, Ronald H H; Gislén, Anna

    2004-01-01

    The camera eyes of fishes and cephalopods have come forth by convergent evolution. In a variety of vertebrates capable of color vision, longitudinal chromatic aberration (LCA) of the optical system is corrected for by the exactly tuned longitudinal spherical aberration (LSA) of the crystalline lens. The LSA leads to multiple focal lengths, such that several wavelengths can be focused on the retina. We investigated whether that is also the case in the firefly squid (Watasenia scintillans), a cephalopod species that is likely to have color vision. It was found that the lens of W. scintillans is virtually free of LSA and uncorrected for LCA. However, the eye does not suffer from LCA because of a banked retina. Photoreceptors sensitive to short and long wavelengths are located at appropriate distances from the lens, such that they receive well-focused images. Such a design is an excellent solution for the firefly squid because a large area of the retina is monochromatically organized and it allows for double use of the surface area in the dichromatically organized part of the retina. However, it is not a universal solution since compensation for LCA by a banked retina requires that eye size and/or spectral separation between photopigments is small.

  6. Optical advantages of astigmatic aberration corrected heliostats

    Science.gov (United States)

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  7. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    Science.gov (United States)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  8. Spectral discrimination in color blind animals via chromatic aberration and pupil shape.

    Science.gov (United States)

    Stubbs, Alexander L; Stubbs, Christopher W

    2016-07-19

    We present a mechanism by which organisms with only a single photoreceptor, which have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide "color-blind" animals with a way to distinguish colors. As a specific example, we constructed a computer model of the visual system of cephalopods (octopus, squid, and cuttlefish) that have a single unfiltered photoreceptor type. We compute a quantitative image quality budget for this visual system and show how chromatic blurring dominates the visual acuity in these animals in shallow water. We quantitatively show, through numerical simulations, how chromatic aberration can be exploited to obtain spectral information, especially through nonaxial pupils that are characteristic of coleoid cephalopods. We have also assessed the inherent ambiguity between range and color that is a consequence of the chromatic variation of best focus with wavelength. This proposed mechanism is consistent with the extensive suite of visual/behavioral and physiological data that has been obtained from cephalopod studies and offers a possible solution to the apparent paradox of vivid chromatic behaviors in color blind animals. Moreover, this proposed mechanism has potential applicability in organisms with limited photoreceptor complements, such as spiders and dolphins.

  9. Spectral discrimination in color blind animals via chromatic aberration and pupil shape

    Science.gov (United States)

    Stubbs, Alexander L.; Stubbs, Christopher W.

    2016-01-01

    We present a mechanism by which organisms with only a single photoreceptor, which have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide “color-blind” animals with a way to distinguish colors. As a specific example, we constructed a computer model of the visual system of cephalopods (octopus, squid, and cuttlefish) that have a single unfiltered photoreceptor type. We compute a quantitative image quality budget for this visual system and show how chromatic blurring dominates the visual acuity in these animals in shallow water. We quantitatively show, through numerical simulations, how chromatic aberration can be exploited to obtain spectral information, especially through nonaxial pupils that are characteristic of coleoid cephalopods. We have also assessed the inherent ambiguity between range and color that is a consequence of the chromatic variation of best focus with wavelength. This proposed mechanism is consistent with the extensive suite of visual/behavioral and physiological data that has been obtained from cephalopod studies and offers a possible solution to the apparent paradox of vivid chromatic behaviors in color blind animals. Moreover, this proposed mechanism has potential applicability in organisms with limited photoreceptor complements, such as spiders and dolphins. PMID:27382180

  10. Correcting chromatic offset in multicolor super-resolution localization microscopy.

    Science.gov (United States)

    Erdelyi, Miklos; Rees, Eric; Metcalf, Daniel; Schierle, Gabriele S Kaminski; Dudas, Laszlo; Sinko, Jozsef; Knight, Alex E; Kaminski, Clemens F

    2013-05-06

    Localization based super-resolution microscopy techniques require precise drift correction methods because the achieved spatial resolution is close to both the mechanical and optical performance limits of modern light microscopes. Multi-color imaging methods require corrections in addition to those dealing with drift due to the static, but spatially-dependent, chromatic offset between images. We present computer simulations to quantify this effect, which is primarily caused by the high-NA objectives used in super-resolution microscopy. Although the chromatic offset in well corrected systems is only a fraction of an optical wavelength in magnitude (super-resolution methods is impossible without appropriate image correction. The simulated data are in excellent agreement with experiments using fluorescent beads excited and localized at multiple wavelengths. Finally we present a rigorous and practical calibration protocol to correct for chromatic optical offset, and demonstrate its efficacy for the imaging of transferrin receptor protein colocalization in HeLa cells using two-color direct stochastic optical reconstruction microscopy (dSTORM).

  11. Chromatic aberration short-wave infrared spectroscopy: nanoparticle spectra without a spectrometer.

    Science.gov (United States)

    Streit, Jason K; Bachilo, Sergei M; Weisman, R Bruce

    2013-02-05

    A new method is described for measuring the short-wave infrared (SWIR) emission wavelengths of numerous individual nanoparticles without using a dedicated spectrometer. Microscope objectives designed for use at visible wavelengths often show severe axial chromatic aberration in the SWIR. This makes coplanar objects emitting at different SWIR wavelengths appear to focus at different depths. After this aberration has been calibrated for a particular objective lens, the depth at which an emissive nanoparticle appears brightest and best focused can be used to deduce its peak emission wavelength. The method is demonstrated using a dilute, structurally polydisperse sample of single-walled carbon nanotubes deposited onto a microscope slide. Discrete emission centers in this sample have different peak wavelengths corresponding to specific nanotube structural species. A set of images was recorded at stepped focus settings and analyzed to find the sharpest focus depth of each nanotube. The chromatic aberration calibration curve converted these depths into peak emission wavelengths with a spectral resolution better than 3 nm, allowing identification of each nanotube's structure. Chromatic aberration spectroscopy is a practical tool for using existing microscopic equipment to extract significant spectral information on coplanar nanoparticle samples that emit or scatter light.

  12. Passive depth estimation using chromatic aberration and a depth from defocus approach.

    Science.gov (United States)

    Trouvé, Pauline; Champagnat, Frédéric; Le Besnerais, Guy; Sabater, Jacques; Avignon, Thierry; Idier, Jérôme

    2013-10-10

    In this paper, we propose a new method for passive depth estimation based on the combination of a camera with longitudinal chromatic aberration and an original depth from defocus (DFD) algorithm. Indeed a chromatic lens, combined with an RGB sensor, produces three images with spectrally variable in-focus planes, which eases the task of depth extraction with DFD. We first propose an original DFD algorithm dedicated to color images having spectrally varying defocus blurs. Then we describe the design of a prototype chromatic camera so as to evaluate experimentally the effectiveness of the proposed approach for depth estimation. We provide comparisons with results of an active ranging sensor and real indoor/outdoor scene reconstructions.

  13. Spectral switches of partially coherent light focused by a filter-lens system with chromatic aberration.

    Science.gov (United States)

    Pu, Jixiong; Cai, Chao; Nemoto, Shojiro

    2004-06-01

    It is shown that when partially coherent polychromatic light is focused by a filter-lens system with chromatic aberration, a spectral shift exists in the focused field, and a spectral switch that is defined as a sharp transition of the spectral shift also takes place at some positions of the focused field. The influence of the chromatic aberration of the lens, the coherence of the partially coherent light in the filter (a circular aperture), the radius of the aperture, and the spectral width of the partially coherent light in the aperture on the spectral shift and the spectral switch are investigated in detail. The numerical results show that these parameters affect the spectral shift and the spectral switch significantly. Potential applications of the spectral shift and the spectral switch of the partially coherent light are discussed.

  14. Errors in confocal fluorescence ratiometric imaging microscopy due to chromatic aberration.

    Science.gov (United States)

    Lin, Yuxiang; Gmitro, Arthur F

    2011-01-01

    Confocal fluorescence ratiometric imaging is an optical technique used to measure a variety of important biological parameters. A small amount of chromatic aberration in the microscope system can introduce a variation in the signal ratio dependent on the fluorophore concentration gradient along the optical axis and lead to bias in the measurement. We present a theoretical model of this effect. Experimental results and simulations clearly demonstrate that this error can be significant and should not be ignored.

  15. Depth position detection for fast moving objects in sealed microchannel utilizing chromatic aberration.

    Science.gov (United States)

    Lin, Che-Hsin; Su, Shin-Yu

    2016-01-01

    This research reports a novel method for depth position measurement of fast moving objects inside a microfluidic channel based on the chromatic aberration effect. Two band pass filters and two avalanche photodiodes (APD) are used for rapid detecting the scattered light from the passing objected. Chromatic aberration results in the lights of different wavelengths focus at different depth positions in a microchannel. The intensity ratio of two selected bands of 430 nm-470 nm (blue band) and 630 nm-670 nm (red band) scattered from the passing object becomes a significant index for the depth information of the passing object. Results show that microspheres with the size of 20 μm and 2 μm can be resolved while using PMMA (Abbe number, V = 52) and BK7 (V = 64) as the chromatic aberration lens, respectively. The throughput of the developed system is greatly enhanced by the high sensitive APDs as the optical detectors. Human erythrocytes are also successfully detected without fluorescence labeling at a high flow velocity of 2.8 mm/s. With this approach, quantitative measurement for the depth position of rapid moving objects inside a sealed microfluidic channel can be achieved in a simple and low cost way.

  16. Aberration-corrected STEM/TEM imaging at 15 kV

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Takeo, E-mail: tasasaki@jeol.co.jp [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sawada, Hidetaka; Hosokawa, Fumio [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sato, Yuta; Suenaga, Kazu [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)

    2014-10-15

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15 kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50 mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192 nm, and the power spectrum of the image showed spots corresponding to distances of 0.111 nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314 nm and 0.192 nm, respectively. At an accelerating voltage of 15 kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase. - Highlights: • Aberration-corrected STEM/TEM imaging at 15 kV demonstrated lattice fringes of Si[110] single crystal with a spacing of 0.192 nm. • To achieve this performance at a lower accelerating voltage, uniform phase area over 50 mrad is mandatory in Ronchigram and Diffractogram tableau. • This means a higher-order aberration of six-fold astigmatism should be compensated. • In addition, decreasing the effect of chromatic aberration plays an important role for improving the performance of linear scattering component at 15 kV TEM.

  17. Accommodation with and without short-wavelength-sensitive cones and chromatic aberration.

    Science.gov (United States)

    Kruger, Philip B; Rucker, Frances J; Hu, Caitlin; Rutman, Hadassa; Schmidt, Nathan W; Roditis, Vasilios

    2005-05-01

    Accommodation was monitored while observers (23) viewed a square-wave grating (2.2 cycles/deg; 0.53 contrast) in a Badal optometer. The grating moved sinusoidally (0.2 Hz) to provide a stimulus between -1.00 D and -3.00 D during trials lasting 40.96 s. There were three illumination conditions: 1. Monochromatic 550 nm light to stimulate long-wavelength-sensitive cones (L-cones) and medium-wavelength-sensitive cones (M-cones) without chromatic aberration; 2. Monochromatic 550 nm light+420 nm light to stimulate long-, medium- and short-wavelength-sensitive cones (S-cones) with longitudinal chromatic aberration (LCA); 3. Monochromatic 550 nm light+420 nm light to stimulate L-, M- and S-cones viewed through an achromatizing lens. In the presence of LCA mean dynamic gain decreased (p=0.0003; ANOVA) and mean accommodation level was reduced (p=0.001; ANOVA). The reduction in gain and increased lag of accommodation in the presence of LCA could result from a blue-yellow chromatic signal or from a larger depth-of-focus.

  18. Three dimensional analysis of chromatic aberration in diffractive elements with extended depth of focus.

    Science.gov (United States)

    Mas, D; Espinosa, J; Perez, J; Illueca, C

    2007-12-24

    The paper presents the polychromatic analysis of two diffractive optical elements with extended depth of focus: the linear axicon and the light sword optical element. Chromatic aberration produces axial displacement of the focal segment line. Thus, we explore the possibility of extending the focal depth of these elements to permit superposition of the chromatic foci. In the case of an axicon, we achieve an achromatic zone where focusing is produced. In the case of the light sword element, we show that the focusing segment is out of axis. Therefore a superposition of colors is produced, but not on axis overlapping. Instead, three colored and separated foci are simultaneously obtained in a single plane. Three dimensional structures of the propagated beams are analyzed in order to provide better understanding of the properties and applications of such elements.

  19. Possibility of decreasing the spherical and chromatic aberrations in plane combined axisymmetric magnetoelectrostatic lenses

    CERN Document Server

    Zhukov, V A; Nesterov, M M

    2001-01-01

    The possibility of decreasing by 6 times the coefficients of both spherical and chromatic aberrations in plane combined axisymmetric lenses in comparison with the purely magnetic lenses is demonstrated. This is provided for by a proper selection of the ratio of the geometric parameters of the electrodes dimensions and pole tags of the combined lens, the electric potentials on its electrodes and the ampere-turns in the excitation coil. Application of the combined lenses may prove to be perspective in the ion and electron projection and microprobe systems

  20. A new aberration-corrected, energy-filtered LEEM/PEEM instrument II. Operation and results

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Hannon, J.B. [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Wan, W. [Ernest Orlando Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mailstop 80R0114, Berkeley, CA 94720 (United States); Berghaus, A.; Schaff, O. [SPECS GmbH, Voltastrasse 5, D-13355 Berlin (Germany)

    2013-04-15

    In Part I we described a new design for an aberration-corrected Low Energy Electron Microscope (LEEM) and Photo Electron Emission Microscope (PEEM) equipped with an in-line electron energy filter. The chromatic and spherical aberrations of the objective lens are corrected with an electrostatic electron mirror that provides independent control of the chromatic and spherical aberration coefficients C{sub c} and C{sub 3}, as well as the mirror focal length. In this Part II we discuss details of microscope operation, how the microscope is set up in a systematic fashion, and we present typical results. - Highlights: ► The C{sub c} and C{sub 3} aberrations of a LEEM/PEEM instrument are corrected with an electrostatic electron mirror. ► The mirror provides independent control over C{sub c}, C{sub 3} and focal length in close agreement with theory. ► A detailed alignment procedure for the corrected microscope is given. ► Novel methods to measure C{sub c} and C{sub 3} of the objective lens and the mirror are presented. ► We demonstrate a record spatial resolution of 2 nm.

  1. Multifocus optical-resolution photoacoustic microscopy using stimulated Raman scattering and chromatic aberration.

    Science.gov (United States)

    Hajireza, Parsin; Forbrich, Alexander; Zemp, Roger J

    2013-08-01

    In this Letter, multifocus optical-resolution photoacoustic microscopy is demonstrated using wavelength tuning and chromatic aberration for depth scanning. Discrete focal zones at several depth locations were created by refocusing light from a polarization-maintaining single-mode fiber pumped by a nanosecond fiber laser. The fiber and laser parameters were chosen to take advantage of stimulated Raman scattering (SRS) in the fiber to create a multiwavelength output that could then be bandpass filtered. The collimator lens and objective lens are chosen to take advantage of chromatic aberration in which each generated SRS wavelength peak focuses at a slightly different depth. The maximum amplitude of photoacoustic signals is mapped to form C-scan images. Additionally, all wavelength peaks fired simultaneously offers improved depth-of-field structural imaging at the cost of slight degradation of mainlobe-to-sidelobe ratios. Wavelength-tuned depth scanning over more than 440 μm is demonstrated, significantly greater than the ~100 μm depth of field predicted from our focused Gaussian beams. The improved depth of focus could be valuable for structural imaging of microvascular morphology without the need for mechanical scanning in the depth direction.

  2. Estimating and controlling chromatic aberration losses for two-junction, two-terminal devices in refractive concentrator systems

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, S.R. [National Renewable Energy Lab., Golden, CO (United States); O`Neill, M.J. [ENTECH, Inc., Keller, TX (United States)

    1996-05-01

    Although previous studies have measured and calculated chromatic aberration losses and proposed methods for reducing these by modifying the optics, significant work remains to be done toward understanding how to quantity the losses and how various parameters affect this loss. This paper presents an analytical definition and calculation method for chromatic aberration losses. The effects of sheet resistance of the midlayers of the cell, total irradiance, incident spectrum, cell width, and diode quality factor are studied. A method for measuring the midlayer resistance in finished sells is described.

  3. Luminance mechanisms mediate the motion of red-green isoluminant gratings: the role of "temporal chromatic aberration".

    Science.gov (United States)

    Mullen, Kathy T; Yoshizawa, Tatsuya; Baker, Curtis L

    2003-05-01

    In this paper we use a dynamic noise-masking paradigm to explore the nature of the mechanisms mediating the motion perception of drifting isoluminant red-green gratings. We compare contrast thresholds for the detection and direction discrimination of drifting gratings (1.5 cpd), over a range of temporal frequencies (0.5-9 Hz) in the presence of variable luminance or chromatic noise. In the first experiment, we used dynamic luminance noise to show that direction thresholds for red-green grating motion are masked by luminance noise over the entire temporal range tested, whereas detection thresholds are unaffected. This result indicates that the motion of nominally isoluminant red-green gratings is mediated by luminance signals. We suggest that stimulus-based luminance artifacts are not responsible for this effect because there is no masking of the detection thresholds. Instead we propose that chromatic motion thresholds for red-green isoluminant gratings are mediated by dynamic luminance artifacts that have an internal, physiological origin. We have termed these "temporal chromatic aberration". In the second experiment, we used dynamic chromatic noise masking to test for a chromatic contribution to red-green grating motion. We were unable to find conclusive evidence for a contribution of chromatic mechanisms to the chromatic grating motion, although a contribution at very high chromatic contrasts cannot be ruled out. Our results add to a growing body of evidence indicating the presence of dynamic, internal luminance artifacts in the motion of chromatic stimuli and we show that these occur even at very low temporal rates. Our results are compatible with our previous work indicating the absence of a chromatic mechanism for first order (quasi-linear) apparent motion [Vision Res. 40 (2000) 1993]. We conclude that previous conclusions based on the motion of chromatic red-green gratings should be reassessed to determine the contribution of dynamic luminance artifacts.

  4. Aberration-corrected STEM/TEM imaging at 15kV.

    Science.gov (United States)

    Sasaki, Takeo; Sawada, Hidetaka; Hosokawa, Fumio; Sato, Yuta; Suenaga, Kazu

    2014-10-01

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192nm, and the power spectrum of the image showed spots corresponding to distances of 0.111nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314nm and 0.192nm, respectively. At an accelerating voltage of 15kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase.

  5. Supersonic Fe beam source for chromatic aberration-free laser focusing of atoms

    CERN Document Server

    Bosch, R C M; Van der Straten, P; Leeuwen, K A H

    2002-01-01

    A monochromatic Fe beam is generated by heated supersonic expansion of argon seeded with Fe vapor. At a nozzle temperature of 1930 K and 800 torr argon inlet pressure the Fe beam has an axial velocity spread of 8% and intensity of 3 x 10 sup 1 sup 5 s sup - sup 1 sr sup - sup 1 , corresponding to a deposition rate of 10 nm/h at 150 mm from the nozzle. The two-chamber alumina crucibles are chemically stable for liquid Fe. With 400 mm sup 3 Fe we have operated for more than 200 hours without reloading. The power consumption at 1930 K is 750 W. Temperature stability at constant power (without feedback) is better than 30 K. The source is intended for deposition of nano-structures by laser focusing of the Fe beam. The small axial velocity spread virtually eliminates the increase in focal spot size due to chromatic aberration. (authors)

  6. Analysis of transverse RMS emittance growth of a beam induced by spherical and chromatic aberration in a solenoidal field

    Energy Technology Data Exchange (ETDEWEB)

    Dash, Radhakanta, E-mail: radhakanta.physics@gmail.com [Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Nayak, Biswaranjan [Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Sharma, Archana; Mittal, Kailash C. [Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2016-01-21

    In a medium energy beam transport line transverse rms emittance growth associated with spherical aberration is analysed. An analytical expression is derived for beam optics in a solenoid field considering terms up to the third order in the radial displacement. Two important phenomena: effect of spherical aberrations in axial-symmetric focusing lens and influence of nonlinear space charge forces on beam emittance growth are discussed for different beam distributions. In the second part nonlinear effect associated with chromatic aberration that describes the growth of emittance and distortion of phase space area is discussed.

  7. Analysis of transverse RMS emittance growth of a beam induced by spherical and chromatic aberration in a solenoidal field

    Science.gov (United States)

    Dash, Radhakanta; Nayak, Biswaranjan; Sharma, Archana; Mittal, Kailash C.

    2016-01-01

    In a medium energy beam transport line transverse rms emittance growth associated with spherical aberration is analysed. An analytical expression is derived for beam optics in a solenoid field considering terms up to the third order in the radial displacement. Two important phenomena: effect of spherical aberrations in axial-symmetric focusing lens and influence of nonlinear space charge forces on beam emittance growth are discussed for different beam distributions. In the second part nonlinear effect associated with chromatic aberration that describes the growth of emittance and distortion of phase space area is discussed.

  8. Analytical calculation of geometric and chromatic aberrations in a bi-potential electrostatic and bell-shaped magnetic combined lens

    CERN Document Server

    Ximen Ji Ye

    2000-01-01

    In the present paper, Gaussian optical property in the bi-potential electrostatic and the bell-shaped magnetic combined lens - a new theoretical model first proposed in electron optics - has been thoroughly studied. Meanwhile, based on electron optical canonical aberration theory, analytical formulas of third-order geometrical and first-order chromatic aberration coefficients and their computational results have first been derived for this bi-potential electrostatic and bell-shaped magnetic combined lens. It is to emphasized that this theoretical study can be used to estimate third-order geometric and first-order chromatic aberrations and to provide a theoretical criterion for numerical computation in a rotationally symmetric electromagnetic lens.

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

    Science.gov (United States)

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

    2016-01-01

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

  10. A Genetic Algorithm for Chromaticity Correction in Diffraction Limited Storage Rings

    CERN Document Server

    Ehrlichman, Michael

    2016-01-01

    An multi-objective genetic algorithm is developed for optimizing nonlinearities in diffraction limited storage rings. This algorithm determines sextupole and octupole strengths for chromaticity correction that deliver optimized dynamic aperture and beam lifetime. The algorithm makes use of dominance constraints to breed desirable properties into the early generations. The momentum aperture is optimized indirectly by constraining the chromatic tune footprint and optimizing the off-energy dynamic aperture. The result is an effective and computationally efficient technique for correcting chromaticity in a storage ring while maintaining optimal dynamic aperture and beam lifetime. This framework was developed for the Swiss Light Source (SLS) upgrade project.

  11. Exploration of chromatic aberration for multiplanar imaging: proof of concept with implications for fast, efficient autofocus.

    Science.gov (United States)

    Weinigel, Martin; Kellner, Albert L; Price, Jeffrey H

    2009-12-01

    Image-based autofocus determines focus directly from the specimen (as opposed to reflective surface positioning with an offset), but sequential acquisition of a stack of images to measure resolution/sharpness and find best focus is slower than reflective positioning. Simultaneous imaging of multiple focal planes, which is also useful for 3D imaging of live cells, is faster but requires complicated optics. With color CCD cameras and white light sources commonly available, we asked if axial chromatic aberration can be utilized to acquire multiple focal planes simultaneously, and if it can be controlled through a range sufficient for practical use. For proof of concept, we theoretically and experimentally explored the focal differences between three narrow wavelength bands on a 3-chip color CCD camera with and without glass inserts of various thicknesses and dispersions. Ray tracing yielded changes in foci of 0.65-0.9 microm upon insertion of 12.5-mm thick glass samples for green (G, 522 nm) vs. blue (B, 462 nm) and green vs. red (G-R, 604 nm). On a microscope: (1) With no glass inserts, the differences in foci were 2.15 microm (G-B) and 0.43 microm (G-R); (2) With glass inserts, the maximum change in foci for G vs. B was 0.44 microm and for G vs. R was 0.26 microm; and (3) An 11.3 mm thick N-BK7 glass insert shifted the foci 0.9 microm (R), 0.6 microm (G), and 0.35 microm (B), such that the B and R foci were farther apart (2.1 microm vs. 1.7 microm) and the R and G foci were closer together (0.25 microm vs. 0.45 microm). The slopes of the differences in foci were dependent on thickness, index of refraction, and dispersion. The measured differences in foci are comparable to the axial steps of 0.1-0.24 microm commonly used for autofocus, and focal plane separation can be altered by inserting optical elements of various dispersions and thicknesses. By enabling acquisition of multiple, axially offset images simultaneously, chromatic aberration, normally an imaging pariah

  12. Analysis and Compensation for Lateral Chromatic Aberration in a Color Coding Structured Light 3D Measurement System.

    Science.gov (United States)

    Huang, Junhui; Xue, Qi; Wang, Zhao; Gao, Jianmin

    2016-09-03

    While color-coding methods have improved the measuring efficiency of a structured light three-dimensional (3D) measurement system, they decreased the measuring accuracy significantly due to lateral chromatic aberration (LCA). In this study, the LCA in a structured light measurement system is analyzed, and a method is proposed to compensate the error caused by the LCA. Firstly, based on the projective transformation, a 3D error map of LCA is constructed in the projector images by using a flat board and comparing the image coordinates of red, green and blue circles with the coordinates of white circles at preselected sample points within the measurement volume. The 3D map consists of the errors, which are the equivalent errors caused by LCA of the camera and projector. Then in measurements, error values of LCA are calculated and compensated to correct the projector image coordinates through the 3D error map and a tri-linear interpolation method. Eventually, 3D coordinates with higher accuracy are re-calculated according to the compensated image coordinates. The effectiveness of the proposed method is verified in the following experiments.

  13. Analysis and Compensation for Lateral Chromatic Aberration in a Color Coding Structured Light 3D Measurement System

    Directory of Open Access Journals (Sweden)

    Junhui Huang

    2016-09-01

    Full Text Available While color-coding methods have improved the measuring efficiency of a structured light three-dimensional (3D measurement system, they decreased the measuring accuracy significantly due to lateral chromatic aberration (LCA. In this study, the LCA in a structured light measurement system is analyzed, and a method is proposed to compensate the error caused by the LCA. Firstly, based on the projective transformation, a 3D error map of LCA is constructed in the projector images by using a flat board and comparing the image coordinates of red, green and blue circles with the coordinates of white circles at preselected sample points within the measurement volume. The 3D map consists of the errors, which are the equivalent errors caused by LCA of the camera and projector. Then in measurements, error values of LCA are calculated and compensated to correct the projector image coordinates through the 3D error map and a tri-linear interpolation method. Eventually, 3D coordinates with higher accuracy are re-calculated according to the compensated image coordinates. The effectiveness of the proposed method is verified in the following experiments.

  14. Numerical correction of aberrations via phase retrieval with speckle illumination

    DEFF Research Database (Denmark)

    Almoro, Percival; Gundu, Phanindra Narayan; Hanson, Steen Grüner

    2009-01-01

    What we believe to be a novel technique for wavefront aberration measurement using speckle patterns is presented. The aberration correction is done numerically. A tilted lens is illuminated with a partially developed speckle field, and the transmitted light intensity is sampled at axially displaced...

  15. TOPICAL REVIEW: Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials

    Directory of Open Access Journals (Sweden)

    Nobuo Tanaka

    2008-01-01

    Full Text Available The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.

  16. Automated spherical aberration correction in scanning confocal microscopy

    NARCIS (Netherlands)

    Yoo, H.W.; Royen, M.E.; van Cappellen, W.A.; Houtsmuller, A.B.; Verhaegen, M.H.G.; Schitter, G.

    2014-01-01

    Mismatch between the refractive indexes of immersion media and glass coverslips introduces spherical aberrations in microscopes especially for high numerical aperture objectives. This contribution demonstrates an automated adjustment of the coverslip correction collar in scanning confocal microscopy

  17. A Novel Mechanism for Color Vision: Pupil Shape and Chromatic Aberration Can Provide Spectral Discrimination for Color Blind Organisms.

    OpenAIRE

    Stubbs, Alexander L.; Stubbs, Christopher William

    2016-01-01

    We present a mechanism by which organisms with only a single photoreceptor, that have a monochromatic view of the world, can achieve color discrimination. The combination of an off axis pupil and the principle of chromatic aberration (where light of different colors focus at different distances behind a lens) can combine to provide color-blind animals with a way to distinguish colors. As a specific example we constructed a computer model of the visual system of cephalopods, (octopus, squid, a...

  18. Restoration of distorted colour microscopic images from transverse chromatic aberration of imperfect lenses.

    Science.gov (United States)

    Wu, H-S; Murray, J; Morgello, S; Fiel, M I; Schiano, T; Kalir, T; Deligdisch, L; Gil, J

    2011-02-01

    An algorithm is presented for restoration of colour microscopic images with distortions from imperfect microscope lenses having transverse chromatic aberrations, resulting in a magnification that slightly varies with wavelengths or colours. The differential of each colour component image is computed as the difference between the component image and its slightly magnified version. The absolute values in the differential component images are generally higher at the edges where greater discontinuities occur. The two cross-correlation functions of the absolute differentials between red and green colours and between red and blue colours are then computed. The maximum in the two cross-correlation functions were sought, respectively, and the cross-correlation delays were then calculated. The two cross-correlation delays were used to determine dispersions and to realign the three colour components. Results of real microscopic images are provided. The restored image and the original are compared both visually and quantitatively in terms of the estimated entropies measured for the degree of concentrations using vector distributions.

  19. Transverse chromatic aberration across the visual field of the human eye.

    Science.gov (United States)

    Winter, Simon; Sabesan, Ramkumar; Tiruveedhula, Pavan; Privitera, Claudio; Unsbo, Peter; Lundström, Linda; Roorda, Austin

    2016-11-01

    The purpose of this study was to measure the transverse chromatic aberration (TCA) across the visual field of the human eye objectively. TCA was measured at horizontal and vertical field angles out to ±15° from foveal fixation in the right eye of four subjects. Interleaved retinal images were taken at wavelengths 543 nm and 842 nm in an adaptive optics scanning laser ophthalmoscope (AOSLO). To obtain true measures of the human eye's TCA, the contributions of the AOSLO system's TCA were measured using an on-axis aligned model eye and subtracted from the ocular data. The increase in TCA was found to be linear with eccentricity, with an average slope of 0.21 arcmin/degree of visual field angle (corresponding to 0.41 arcmin/degree for 430 nm to 770 nm). The absolute magnitude of ocular TCA varied between subjects, but was similar to the resolution acuity at 10° in the nasal visual field, encompassing three to four cones. Therefore, TCA can be visually significant. Furthermore, for high-resolution imaging applications, whether visualizing or stimulating cellular features in the retina, it is important to consider the lateral displacements between wavelengths and the variation in blur over the visual field.

  20. Effects of ocular transverse chromatic aberration on near foveal letter recognition.

    Science.gov (United States)

    Yang, Shun-nan; Tai, Yu-chi; Laukkanen, Hannu; Sheedy, James

    2009-11-01

    Transverse chromatic aberration (TCA) smears retinal images of peripheral stimuli. In reading, text information is extracted from both foveal and near fovea, where TCA magnitude is relatively small and variable. The present study investigated whether TCA significantly affects near foveal letter identification. Subjects were briefly presented a string of five letters centered one degree of visual angle to the left or right of fixation. They indicated whether the middle letter was the same as a comparison letter subsequently presented. Letter strings were rendered with a reddish fringe on the left edge of each letter and a bluish fringe on the right edge, consistent with expected left periphery TCA, or with the opposite fringe consistent with expected right periphery TCA. Effect of the color fringing on letter recognition was measured by comparing the response accuracy for fringed and non-fringed stimuli. Effects of lateral interference were examined by manipulating inter-letter spacing and similarity of neighboring letters. Results demonstrated significantly improved response accuracy with the color fringe opposite to the expected TCA, but decreased accuracy when consistent with it. Narrower letter spacing exacerbated the effect of the color fringe, whereas letter similarity did not. Our results suggest that TCA significantly reduces the ability to recognize letters in the near fovea by impeding recognition of individual letters and by enhancing lateral interference between letters.

  1. Orbit, optics and chromaticity correction for PS2 negative momentum compaction lattices

    Energy Technology Data Exchange (ETDEWEB)

    Papaphilippou,Y.; Barranco, J.; Bartmann, W.; Benedikt, M.; Carli, C.; de Maria, R.; Peggs, S.; Trbojevic, D.

    2009-05-04

    The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattice of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the lattice is finally evaluated.

  2. Automated computational aberration correction method for broadband interferometric imaging techniques.

    Science.gov (United States)

    Pande, Paritosh; Liu, Yuan-Zhi; South, Fredrick A; Boppart, Stephen A

    2016-07-15

    Numerical correction of optical aberrations provides an inexpensive and simpler alternative to the traditionally used hardware-based adaptive optics techniques. In this Letter, we present an automated computational aberration correction method for broadband interferometric imaging techniques. In the proposed method, the process of aberration correction is modeled as a filtering operation on the aberrant image using a phase filter in the Fourier domain. The phase filter is expressed as a linear combination of Zernike polynomials with unknown coefficients, which are estimated through an iterative optimization scheme based on maximizing an image sharpness metric. The method is validated on both simulated data and experimental data obtained from a tissue phantom, an ex vivo tissue sample, and an in vivo photoreceptor layer of the human retina.

  3. Filtering Chromatic Aberration for Wide Acceptance Angle Electrostatic Lenses II--Experimental Evaluation and Software-Based Imaging Energy Analyzer.

    Science.gov (United States)

    Fazekas, Ádám; Daimon, Hiroshi; Matsuda, Hiroyuki; Tóth, László

    2016-03-01

    Here, the experimental results of the method of filtering the effect of chromatic aberration for wide acceptance angle electrostatic lens-based system are described. This method can eliminate the effect of chromatic aberration from the images of a measured spectral image sequence by determining and removing the effect of higher and lower kinetic energy electrons on each different energy image, which leads to significant improvement of image and spectral quality. The method is based on the numerical solution of a large system of linear equations and equivalent with a multivariate strongly nonlinear deconvolution method. A matrix whose elements describe the strongly nonlinear chromatic aberration-related transmission function of the lens system acts on the vector of the ordered pixels of the distortion free spectral image sequence, and produces the vector of the ordered pixels of the measured spectral image sequence. Since the method can be applied not only on 2D real- and $k$ -space diffraction images, but also along a third dimension of the image sequence that is along the optical or in the 3D parameter space, the energy axis, it functions as a software-based imaging energy analyzer (SBIEA). It can also be applied in cases of light or other type of optics for different optical aberrations and distortions. In case of electron optics, the SBIEA method makes possible the spectral imaging without the application of any other energy filter. It is notable that this method also eliminates the disturbing background significantly in the present investigated case of reflection electron energy loss spectra. It eliminates the instrumental effects and makes possible to measure the real physical processes better.

  4. Chick eyes compensate for chromatic simulations of hyperopic and myopic defocus: evidence that the eye uses longitudinal chromatic aberration to guide eye-growth.

    Science.gov (United States)

    Rucker, Frances J; Wallman, Josh

    2009-07-01

    Longitudinal chromatic aberration (LCA) causes short wavelengths to be focused in front of long wavelengths. This chromatic signal is evidently used to guide ocular accommodation. We asked whether chick eyes exposed to static gratings simulating the chromatic effects of myopic or hyperopic defocus would "compensate" for the simulated defocus. We alternately exposed one eye of each chick to a sine-wave grating (5 or 2 cycle/deg) simulating myopic defocus ("MY defocus": image focused in front of retina; hence, red contrast higher than blue) and the other eye to a grating of the same spatial frequency simulating hyperopic defocus ("HY defocus": blue contrast higher than red). The chicks were placed in a drum with one eye covered with one grating, and then switched to another drum with the other grating with the other eye covered. To minimize the effects of altered eye-growth on image contrast, we studied only the earliest responses: first, we measured changes in choroidal thickness 45 min to 1 h after one 15-min episode in the drum, then we measured glycosaminoglycans (GAG) synthesis in sclera and choroid (by the incorporation of labeled sulfate in tissue culture) after a day of four 30-min episodes in the drum. The eyes compensated in the appropriate directions: The choroids of the eyes exposed to the HY simulation showed significantly more thinning (less thickening) over the course of the experiment than the choroids of the eyes exposed to the MY simulation (all groups mean:-17 microm; 5 c/d groups: -24 microm; paired t-test (one-tailed): p=0.0006). The rate of scleral GAG synthesis in the eye exposed to the HY simulation was significantly greater than in the eye exposed to the MY simulation (HY/MY ratio=1.20; one sample t-test (one-tailed): p=0.015). There was no significant interaction between the sign of the simulated defocus and either the spatial frequency or the presence of a +3 D lens used to compensate for the 33 cm distance of the drum. Although previous

  5. Spectral sensitivity of the concave mirror eyes of scallops: potential influences of habitat, self-screening and longitudinal chromatic aberration.

    Science.gov (United States)

    Speiser, Daniel I; Loew, Ellis R; Johnsen, Sönke

    2011-02-01

    Scallop eyes contain two retinas, one proximal and one distal. Molecular evidence suggests that each retina expresses a different visual pigment. To test whether these retinas have different spectral sensitivities, we used microspectrophotometry to measure the absorption spectra of photoreceptors from the eyes of two different scallop species. Photoreceptors from the proximal and distal retinas of the sea scallop Placopecten magellanicus had absorption peak wavelengths (λ(max)) of 488 ± 1 nm (mean ± s.e.m.; N=20) and 513 ± 3 nm (N=26), respectively. Photoreceptors from the corresponding retinas of the bay scallop Argopecten irradians had λ(max) values of 506 ± 1 nm (N=21) and 535 ± 3 nm (N=14). Assuming that the proximal and distal receptors had equal absorption coefficients (k(D)=0.0067 microm(-1)), we found that self-screening within the scallop eye caused the proximal and distal receptors in P. magellanicus to have peak absorption at 490 and 520 nm, respectively, and the corresponding receptors in A. irradians to have peak absorption at 504 and 549 nm. We conclude that environment may influence the λ(max) of scallop visual pigments: P. magellanicus, generally found in blue oceanic water, has visual pigments that are maximally sensitive to shorter wavelengths than those found in A. irradians, which lives in greener inshore water. Scallop distal retinas may be sensitive to longer wavelengths of light than scallop proximal retinas to correct for either self-screening by the retinas or longitudinal chromatic aberration of the lens.

  6. SMART:. An Aberration-Corrected XPEEM/LEEM with Energy Filter

    Science.gov (United States)

    Wichtendahl, R.; Fink, R.; Kuhlenbeck, H.; Preikszas, D.; Rose, H.; Spehr, R.; Hartel, P.; Engel, W.; Schlögl, R.; Freund, H.-J.; Bradshaw, A. M.; Lilienkamp, G.; Schmidt, Th.; Bauer, E.; Benner, G.; Umbach, E.

    A new UHV spectroscopic X-ray photoelectron emission and low energy electron microscope is presently under construction for the installation at the PM-6 soft X-ray undulator beamline at BESSY II. Using a combination of a sophisticated magnetic beam splitter and an electrostatic tetrode mirror, the spherical and chromatic aberrations of the objective lens are corrected and thus the lateral resolution and sensitivity of the instrument improved. In addition a corrected imaging energy filter (a so-called omega filter) allows high spectral resolution (ΔE=0.1 eV) in the photoemission modes and back-ground suppression in LEEM and small-spot LEED modes. The theoretical prediction for the lateral resolution is 5 Å a realistic goal is about 2 nm. Thus, a variety of electron spectroscopies (XAS, XPS, UPS, XAES) and electron diffraction (LEED, LEEM) or reflection techniques (MEM) will be available with spatial resolution unreached so far.

  7. The role of short-wavelength sensitive cones and chromatic aberration in the response to stationary and step accommodation stimuli.

    Science.gov (United States)

    Rucker, Frances J; Kruger, Philip B

    2004-01-01

    The aim of the experiment was to test for a contribution from short-wavelength sensitive cones to the static and step accommodation response, to compare responses from short and long- plus middle-wavelength sensitive cone types, and to examine the contribution of a signal from longitudinal chromatic aberration to the accommodation response. Accommodation was monitored continuously (eight subjects) to a square-wave grating (2.2 c/d; 0.57 contrast) in a Badal optometer. The grating stepped (1.00 D) randomly towards or away from the eye from a starting position of 2.00 D. Five illumination conditions were used to isolate cone responses, and combine them with or without longitudinal chromatic aberration. Accuracy of the response before the step, step amplitude, latencies and time-constants, were compared between conditions using single factor ANOVA and t-test comparisons. Both S-cones and LM-cones mediated static and step accommodation responses. S-cone contrast drives "static" accommodation for near, but the S-cone response is too slow to influence step dynamics when LM-cones participate.

  8. The main injector chromaticity correction sextupole magnets: Measurements and operating schemes

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; Bogacz, A.; Brown, B.C.; Harding, D.J.; Fang, S.J.; Martin, P.S.; Glass, H.D.; Sim, J.

    1995-05-01

    The Fermilab Main Injector (FMI) is a high intensity proton synchrotron which will be used to accelerate protons and antiprotons from 8.9 GeV/c to 150 GeV/c. The natural chromaticities of the machine for the horizontal and the vertical Planes are {minus}33.6 and {minus}33.9 respectively. The {Delta}p/p of the beam at injection is about 0.002. The chromaticity requirements of the FMI, are primarily decided by the {Delta}p/p = 0.002 of the beam at injection. This limits the final chromaticity of the FMI to be {plus_minus}5 units. To correct the chromaticity in the FMI two families of sextupole magnets will be installed in the lattice, one for each plane. A sextupole magnet suitable for the FMI needs has been designed and a number of them are being built. New chromaticity compensation schemes have been worked out in the light of recently proposed faster acceleration ramps. On an R/D sextupole magnet the low current measurements have been carried out to determine the electrical properties. Also, using a Morgan coil, measurements have been performed to determine the higher ordered multipole components up to 18-poles. An overview of these result are presented here.

  9. Differential aberration correction (DAC) microscopy: a new molecular ruler.

    Science.gov (United States)

    Vallotton, P

    2008-11-01

    Considerable efforts have been deployed towards measuring molecular range distances in fluorescence microscopy. In the 1-10 nm range, Förster energy transfer microscopy is difficult to beat. Above 300 nm, conventional diffraction limited microscopy is suitable. We introduce a simple experimental technique that allows bridging the gap between those two resolution scales in both 2D and 3D with a resolution of about 20 nm. The method relies on a computational approach to accurately correct optical aberrations over the whole field of view. The method is differential because the probes of interest are affected in exactly the same manner by aberrations as are the reference probes used to construct the aberration deformation field. We expect that this technique will have significant implications for investigating structural and functional questions in bio-molecular sciences.

  10. Influence of ocular longitudinal chromatic aberration on the selection of aspheric intraocular lenses.

    Science.gov (United States)

    Hong, Xin; Choi, Myoung

    2010-12-06

    Polychromatic defocus could affect the optimal residual spherical aberration that could yield the best image quality for patients with intraocular lenses (IOLs). Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus. The maximum MTF volume occurred at + 0.05 μm of overall ocular spherical aberration. For 3 case studies, the optimal overall ocular spherical aberration was ~0.05 μm more positive with the contribution of polychromatic defocus than without it. Overall, the model indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.

  11. Aberration correction for time-domain ultrasound diffraction tomography.

    Science.gov (United States)

    Mast, T Douglas

    2002-07-01

    Extensions of a time-domain diffraction tomography method, which reconstructs spatially dependent sound speed variations from far-field time-domain acoustic scattering measurements, are presented and analyzed. The resulting reconstructions are quantitative images with applications including ultrasonic mammography, and can also be considered candidate solutions to the time-domain inverse scattering problem. Here, the linearized time-domain inverse scattering problem is shown to have no general solution for finite signal bandwidth. However, an approximate solution to the linearized problem is constructed using a simple delay-and-sum method analogous to "gold standard" ultrasonic beamforming. The form of this solution suggests that the full nonlinear inverse scattering problem can be approximated by applying appropriate angle- and space-dependent time shifts to the time-domain scattering data; this analogy leads to a general approach to aberration correction. Two related methods for aberration correction are presented: one in which delays are computed from estimates of the medium using an efficient straight-ray approximation, and one in which delays are applied directly to a time-dependent linearized reconstruction. Numerical results indicate that these correction methods achieve substantial quality improvements for imaging of large scatterers. The parametric range of applicability for the time-domain diffraction tomography method is increased by about a factor of 2 by aberration correction.

  12. Accounting for Chromatic Atmospheric Effects on Barycentric Corrections

    Science.gov (United States)

    Blackman, Ryan T.; Szymkowiak, Andrew E.; Fischer, Debra A.; Jurgenson, Colby A.

    2017-03-01

    Atmospheric effects on stellar radial velocity measurements for exoplanet discovery and characterization have not yet been fully investigated for extreme precision levels. We carry out calculations to determine the wavelength dependence of barycentric corrections across optical wavelengths, due to the ubiquitous variations in air mass during observations. We demonstrate that radial velocity errors of at least several cm s‑1 can be incurred if the wavelength dependence is not included in the photon-weighted barycentric corrections. A minimum of four wavelength channels across optical spectra (380–680 nm) are required to account for this effect at the 10 cm s‑1 level, with polynomial fits of the barycentric corrections applied to cover all wavelengths. Additional channels may be required in poor observing conditions or to avoid strong telluric absorption features. Furthermore, consistent flux sampling on the order of seconds throughout the observation is necessary to ensure that accurate photon weights are obtained. Finally, we describe how a multiple-channel exposure meter will be implemented in the EXtreme PREcision Spectrograph (EXPRES).

  13. Chromatic error correction of diffractive optical elements at minimum etch depths

    Science.gov (United States)

    Barth, Jochen; Gühne, Tobias

    2014-09-01

    The integration of diffractive optical elements (DOE) into an optical design opens up new possibilities for applications in sensing and illumination. If the resulting optics is used in a larger spectral range we must correct not only the chromatic error of the conventional, refractive, part of the design but also of the DOE. We present a simple but effective strategy to select substrates which allow the minimum etch depths for the DOEs. The selection depends on both the refractive index and the dispersion.

  14. Longitudinal chromatic aberration of the human eye in the visible and near infrared from wavefront sensing, double-pass and psychophysics.

    Science.gov (United States)

    Vinas, Maria; Dorronsoro, Carlos; Cortes, Daniel; Pascual, Daniel; Marcos, Susana

    2015-03-01

    Longitudinal Chromatic Aberration (LCA) influences the optical quality of the eye. However, the reported LCA varies across studies, likely associated to differences in the measurement techniques. We present LCA measured in subjects using wavefront sensing, double-pass retinal images, and psychophysical methods with a custom-developed polychromatic Adaptive Optics system in a wide spectral range (450-950 nm), with control of subjects' natural aberrations. LCA measured psychophysically was significantly higher than that from reflectometric techniques (1.51 D vs 1.00 D in the 488-700 nm range). Ours results indicate that the presence of natural aberrations is not the cause for the discrepancies across techniques.

  15. Analytical and numerical analysis of third-order geometric and first-order chromatic aberrations in a bi-potential electrostatic lens

    CERN Document Server

    Xi Men Jiye

    2000-01-01

    Glaser and Robl (Z. Angew. Math. Phys. 2 (1951) 444) first proposed a theoretical model for a bi-potential electrostatic lens, whose axial potential distribution satisfies the law of electrostatics and whose paraxial trajectory equation is soluble. In this paper, the Gaussian optical property in the bi-potential electrostatic lens has been thoroughly studied. Meanwhile, based on electron optical canonical aberration theory, analytical formulas of third-order geometrical and first-order chromatic aberration coefficients have first been derived and their computational results obtained for this bi-potential electrostatic lens. It is to be emphasized that this theoretical study can be used to estimate third-order geometric and first-order chromatic aberrations and to provide a theoretical criterion for numerical computation in a rotationally symmetric electrostatic immersion lens.

  16. Improvement of depth resolution of ADF-SCEM by deconvolution: effects of electron energy loss and chromatic aberration on depth resolution.

    Science.gov (United States)

    Zhang, Xiaobin; Takeguchi, Masaki; Hashimoto, Ayako; Mitsuishi, Kazutaka; Tezuka, Meguru; Shimojo, Masayuki

    2012-06-01

    Scanning confocal electron microscopy (SCEM) is a new imaging technique that is capable of depth sectioning with nanometer-scale depth resolution. However, the depth resolution in the optical axis direction (Z) is worse than might be expected on the basis of the vertical electron probe size calculated with the existence of spherical aberration. To investigate the origin of the degradation, the effects of electron energy loss and chromatic aberration on the depth resolution of annular dark-field SCEM were studied through both experiments and computational simulations. The simulation results obtained by taking these two factors into consideration coincided well with those obtained by experiments, which proved that electron energy loss and chromatic aberration cause blurs at the overfocus sides of the Z-direction intensity profiles rather than degrade the depth resolution much. In addition, a deconvolution method using a simulated point spread function, which combined two Gaussian functions, was adopted to process the XZ-slice images obtained both from experiments and simulations. As a result, the blurs induced by energy loss and chromatic aberration were successfully removed, and there was also about 30% improvement in the depth resolution in deconvoluting the experimental XZ-slice image.

  17. APPLICATION OF THE LONGITUDINAL CHROMATIC ABERRATION EFFECT FOR DISTANCES MEASUREMENT ON THE BASIS OF A SINGLE PHOTO

    Directory of Open Access Journals (Sweden)

    M. A. Volkova

    2016-03-01

    Full Text Available Subject of Research. We propose a method for measuring the distances to the surfaces of photographed objects based on the effect of longitudinal chromatic aberration. According to this effect, the focal length of lens depends on the wavelength of refracted light, thus the defocus of image formed by lens depends not only on the distance from image plane to lens, but also on the wavelength of light the picture was taken for (red, green or blue color ranges. Method. The proposed method of distance measurement is based on comparison of image defocus for different wavelengths (e.g., red and blue. The comparison is performed in the spatial frequency domain and is based on analysis of image complex spectrograms (the Fourier spectrum calculated locally within a window scanning the image.The distance to each point of photographed surface is calculated in closed form by the analysis of local spatial spectrum with the use of Gaussian model of point spread function. Main Results. The working capacity of distance measurement technique is partially verified on the basis of image defocus imitation by different displacement of objective lens with respect to sensor matrix of camera. The presented analysis of chromatic parameters of traditionally applied optical materials also proves the physical realizability of proposed technique. A technology is also proposed for distance measuring based on really differing image defocus in different color channels applying a special calibration of electro-optical system. Practical Relevance. The proposed distance measurement technique could be practically useful in the cases where any active illumination of objects being photographed is prohibited. It is also worth to be applied in the inexpensive low-sized optical measuring devices like Kinect for Xbox-360.

  18. The effects of longitudinal chromatic aberration and a shift in the peak of the middle-wavelength sensitive cone fundamental on cone contrast.

    Science.gov (United States)

    Rucker, F J; Osorio, D

    2008-09-01

    Longitudinal chromatic aberration is a well-known imperfection of visual optics, but the consequences in natural conditions, and for the evolution of receptor spectral sensitivities are less well understood. This paper examines how chromatic aberration affects image quality in the middle-wavelength sensitive (M-) cones, viewing broad-band spectra, over a range of spatial frequencies and focal planes. We also model the effects on M-cone contrast of moving the M-cone fundamental relative to the long- and middle-wavelength (L- and M-cone) fundamentals, while the eye is accommodated at different focal planes or at a focal plane that maximizes luminance contrast. When the focal plane shifts towards longer (650 nm) or shorter wavelengths (420 nm) the effects on M-cone contrast are large: longitudinal chromatic aberration causes total loss of M-cone contrast above 10-20 c/d. In comparison, the shift of the M-cone fundamental causes smaller effects on M-cone contrast. At 10 c/d a shift in the peak of the M-cone spectrum from 560 to 460 nm decreases M-cone contrast by 30%, while a 10 nm blue-shift causes only a minor loss of contrast. However, a noticeable loss of contrast may be seen if the eye is focused at focal planes other than that which maximizes luminance contrast. The presence of separate long- and middle-wavelength sensitive cones therefore has a small, but not insignificant cost to the retinal image via longitudinal chromatic aberration. This aberration may therefore be a factor limiting evolution of visual pigments and trichromatic color vision.

  19. Influence of Misalignment on High-Order Aberration Correction for Normal Human Eyes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hao-Xin; XU Bing; XUE Li-Xia; DAI Yun; LIU Qian; RAO Xue-Jun

    2008-01-01

    @@ Although a compensation device can correct aberrations of human eyes, the effect will be degraded by its misalignment, especially for high-order aberration correction. We caJculate the positioning tolerance of correction device for high-order aberrations, and within what degree the correcting effect is better than low-order aberration (defocus and astigmatism) correction. With fixed certain misalignment within the positioning tolerance, we calculate the residual wavefront rms aberration of the first-6 to first-35 terms along with the 3rd-5th terms of aberrations corrected, and the combined first-13 terms of aberrations are also studied under the same quantity of misalignment. However, the correction effect of high-order aberrations does not meliorate along with the increase of the high-order terms under some misalignment, moreover, some simple combined terms correction can achieve similar result as complex combinations. These results suggest that it is unnecessary to correct too much the terms of high-order aberrations which are diffcult to accomplish in practice, and gives confdence to correct high-order aberrations out of the laboratory.

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

    Institute of Scientific and Technical Information of China (English)

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

    2015-01-01

    ·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.

  1. Feed-Forward Corrections for Tune and Chromaticity Injection Decay During 2015 LHC Operation

    CERN Document Server

    Solfaroli Camillocci, Matteo; Lamont, Mike; Schaumann, Michaela; Todesco, Ezio; Wenninger, Jorg

    2016-01-01

    After two years of shutdown, the Large Hadron Collider (LHC) has been operated in 2015 at 6.5 TeV, close to its designed energy. When the current is stable at low field, the harmonic components of the main circuits are subject to a dynamic variation induced by current redistribution on the superconducting cables. The Field Description of the LHC (FiDel) foresaw an increase of the decay at injection of tune (quadrupolar components) and chromaticity (sextupolar components) of about 50% with respect to LHC Run1 due to the higher operational current. This paper discusses the beam-based measurements of the decay during the injection plateau and the implementation and accuracy of the feed-forward corrections as present in 2015. Moreover, the observed tune shift proportional to the circulating beam intensity and it's foreseen feed-forward correction are covered.

  2. Chromatic effects in beam wander correction for free-space quantum communications

    CERN Document Server

    Carrasco-Casado, Alberto; Fernandez, Veronica

    2016-01-01

    Beam wander caused by atmospheric turbulence can significantly degrade the performance of horizontal free-space quantum communication links. Classical beam wander correction techniques cannot be applied due to the stronger requirements of transmitting single photons. One strategy to overcome this limitation consists in using a separate wavelength from that of the quantum signal to analyze the beam wander and use this information for its correction. For this strategy to work adequately, both wavelengths should be affected equally by atmospheric turbulence, i.e. no chromatic effects should be originated from beam wander. In this letter, a series of experiments are performed to prove that this is the case for {\\lambda} ~ 850 nm as the quantum signal and {\\lambda} ~ 1550 nm as the tracking signal of a quantum communication system.

  3. Vision improvement by correcting higher-order aberrations with customized soft contact lenses in keratoconic eyes

    Science.gov (United States)

    Sabesan, Ramkumar; Jeong, Tae Moon; Carvalho, Luis; Cox, Ian G.; Williams, David R.; Yoon, Geunyoung

    2007-04-01

    Higher-order aberration correction in abnormal eyes can result in significant vision improvement, especially in eyes with abnormal corneas. Customized optics such as phase plates and customized contact lenses are one of the most practical, nonsurgical ways to correct these ocular higher-order aberrations. We demonstrate the feasibility of correcting higher-order aberrations and improving visual performance with customized soft contact lenses in keratoconic eyes while compensating for the static decentration and rotation of the lens. A reduction of higher-order aberrations by a factor of 3 on average was obtained in these eyes. The higher-order aberration correction resulted in an average improvement of 2.1 lines in visual acuity over the conventional correction of defocus and astigmatism alone.

  4. Aspherical surfaces design for extreme ultraviolet lithographic objective with correction of thermal aberration

    Science.gov (United States)

    Liu, Yan; Li, Yanqiu

    2016-09-01

    At present, few projection objectives for extreme ultraviolet (EUV) lithography pay attention to correct thermal aberration in optical design phase, which would lead to poor image quality in a practical working environment. We present an aspherical modification method for helping the EUV lithographic objective additionally correct the thermal aberration. Based on the thermal aberration and deformation predicted by integrated optomechanical analysis, the aspherical surfaces in an objective are modified by an iterative algorithm. The modified aspherical surfaces could correct the thermal aberration and maintain the initial high image quality in a practical working environment. A six-mirror EUV lithographic objective with 0.33-numerical aperture is taken as an example to illustrate the presented method. The results show that the thermal aberration can be corrected effectively, and the image quality of the thermally deformed system is improved to the initial design level, which proves the availability of the method.

  5. Brief history of the Cambridge STEM aberration correction project and its progeny

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L. Michael [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Batson, Philip E. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics, Rutgers University, Piscataway, NJ 08854 (United States); Department of Materials Science, Rutgers University, Piscataway, NJ 08854 (United States); Dellby, Niklas [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Krivanek, Ondrej L. [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2015-10-15

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope.

  6. Study on the modification of measured wavefront aberration data for customized visual correction

    Science.gov (United States)

    Liu, Ming; Zhang, Yong; Zhang, Zhidong; Quan, Wei; An, Li

    2008-12-01

    Wavefront aberration of human eye is an important foundation for customized vision correction. In most current aberrometers, near infrared light is used to measure ocular wavefront aberration, whereas for customized visual correction, wavefront aberration data in visible range are required. With the measured wavefront aberration, corneal topography and eye's axial lengths data, individual eye models for twenty normal human eyes are constructed with the optical design software ZEMAX. Changing the incidence light wavelength and the refractive indexes of eye models, the values of defocus, astigmatism, higher-order aberrations in the measuring wavelength (833nm) and at the most sensitive wavelength of human eye (555nm) are obtained. Average focus shift between 833nm and 555nm is found to be about 0.94D, and different slightly for different individuals; the differences of astigmatism and higher-order aberrations between 833nm and 555nm are quite slight. For customized visual correction, the measured defocus value should be modified, whereas the measured astigmatism and higher-order aberrations could be used directly for the current correction precision. Individual eye model is a useful tool for accurate transformation of the measured wavefront aberration data into the data for visible spectrum.

  7. Focus correction in an apodized system with spherical aberration.

    Science.gov (United States)

    Bernal-Molina, Paula; Castejón-Mochón, José Francisco; Bradley, Arthur; López-Gil, Norberto

    2015-08-01

    We performed a theoretical and computational analysis of the through-focus axial irradiance in a system with a Gaussian amplitude pupil function and fourth- and sixth-order spherical aberration (SA). Two cases are analyzed: low aberrated systems, and the human eye containing significant levels of SA and a natural apodization produced by the Stiles-Crawford effect. Results show that apodization only produces a refraction change of the plane that maximized the Strehl ratio for eyes containing significant levels of negative SA.

  8. Improvement of the beam quality by chromaticity correction for wavelength shortening in the NIJI-IV FEL

    CERN Document Server

    Sei, N; Ohgaki, H; Litvinenko, V N; Mikado, T; Yamazaki, T

    1999-01-01

    Electron-beam qualities improved by chromaticity correction in the storage ring NIJI-IV were investigated at the beam energy of 309 MeV. Sextupole-quadrupole-sextupole (SQS) magnets, which were installed in all of the short-straight sections in NIJI-IV, perfectly corrected a horizontal and a vertical chromaticity. This improvement suppressed a head-tail instability, so that higher beam current (approx 30 mA) and higher peak-electron density (approx 6x10 sup 1 sup 6 m sup - sup 3) were available for FEL experiments. The maximum FEL gain was estimated to be about 2.5% at a wavelength of 240 nm. The lasing of an FEL around 300 nm was achieved in March 1998, and the lasing of an FEL at around 240 nm was successfully observed in May 1998. The shortest wavelength of FELs with the NIJI-IV FEL system was 228 nm.

  9. Fringing field correction of the second-order angular aberration in sector field electron energy analyzers

    Energy Technology Data Exchange (ETDEWEB)

    Yavor, M.I. [Institute for Analytical Instrumentation RAS, 190103 St. Petersburg (Russian Federation)], E-mail: mikhail.yavor@gmail.com; Belov, V.D.; Pomozov, T.V. [Institute for Analytical Instrumentation RAS, 190103 St. Petersburg (Russian Federation)

    2008-12-15

    A new way of correcting the second-order angular aberration in sector field and polar-toroidal electron energy analyzers with object and image located outside the field is proposed. Correction is performed by biasing the optic axis electrostatic potential inside the analyzer with respect to the potential of surrounding field-free space. The strength of the correcting aberration concentrated in the fringing field regions of the analyzer is calculated with the aid of the fringing field integral method. The described correction allows achieving second-order focusing and thus increasing the energy resolving power in sector field analyzers, in particular used for angle resolved energy measurements.

  10. Correction of Optical Aberrations in Elliptic Neutron Guides

    CERN Document Server

    Bentley, Phillip M; Andersen, Ken H; Rodriguez, Damian Martin; Mildner, David F R

    2012-01-01

    Modern, nonlinear ballistic neutron guides are an attractive concept in neutron beam delivery and instrumentation, because they offer increased performance over straight or linearly tapered guides. However, like other ballistic geometries they have the potential to create significantly non-trivial instrumental resolution functions. We address the source of the most prominent optical aberration, namely coma, and we show that for extended sources the off-axis rays have a different focal length from on-axis rays, leading to multiple reflections in the guide system. We illustrate how the interplay between coma, sources of finite size, and mirrors with non-perfect reflectivity can therefore conspire to produce uneven distributions in the neutron beam divergence, the source of complicated resolution functions. To solve these problems, we propose a hybrid elliptic-parabolic guide geometry. Using this new kind of neutron guide shape, it is possible to condition the neutron beam and remove almost all of the aberration...

  11. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Faergeman, Nils J

    2008-01-01

    Intrinsically fluorescent sterols, like dehydroergosterol (DHE), mimic cholesterol closely and are therefore suitable to determine cholesterol transport by fluorescence microscopy. Disadvantages of DHE are its low quantum yield, rapid bleaching, and the fact that its excitation and emission...

  12. Improving the quality perception of digital images using modified method of the eye aberration correction

    Science.gov (United States)

    Kvyetnyy, Roman; Sofina, Olga; Orlyk, Pavel; Utreras, Andres J.; Smolarz, Andrzej; Wójcik, Waldemar; Orazalieva, Sandugash

    2016-09-01

    A new approach to solve the problem of image correction to improve the quality perception of graphic information by people with aberrations of the eye optical system is considered in given article. The model of higher order aberrations which may appear in the human eye optical system is described. The developed approach is based on the pre-processing of digital images and applying of the filtration methods to the adjusted images.

  13. Environmental Transmission Electron Microscopy in an Aberration-Corrected Environment

    DEFF Research Database (Denmark)

    Hansen, Thomas W.; Wagner, Jakob B.

    2012-01-01

    The increasing use of environmental transmission electron microscopy (ETEM) in materials science provides exciting new possibilities for investigating chemical reactions and understanding both the interaction of fast electrons with gas molecules and the effect of the presence of gas on high......-resolution imaging. A gaseous atmosphere in the pole-piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 100 nm), the gas in the environmental...... cell fills the entire gap between the pole pieces and is thus not spatially localized. By using an FEI Titan environmental transmission electron microscope equipped with a monochromator and an aberration corrector on the objective lens, we have investigated the effects on imaging and spectroscopy...

  14. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    Science.gov (United States)

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  15. Brief history of the Cambridge STEM aberration correction project and its progeny.

    Science.gov (United States)

    Brown, L Michael; Batson, Philip E; Dellby, Niklas; Krivanek, Ondrej L

    2015-10-01

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper "In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday", recently published in Ultramicroscopy.

  16. Conformal optical design with combination of static and dynamic aberration corrections

    Institute of Scientific and Technical Information of China (English)

    Li Yan; Li Lin; Huang Yi-Fan; Liu Jia-Guo

    2009-01-01

    Conformal domes that are shaped to meet aerodynamic requirements can increase range and speed for the host platform. Because these domes typically deviate greatly from spherical surface descriptions, a variety of aberrations are induced which vary with the field-of-regard (FOR) angle. A system for correcting optical aberrations created by a conformal dome has an outer surface and an inner surface. Optimizing the inner surface is regard as static aberration correction. A deformable mirror is placed at the position of the secondary mirror in the two-mirror all reflective imaging system, which is the dynamic aberration correction. An ellipsoidal MgF2 conformal dome with a fineness ratio of 1.0 is designed as an example. The FOR angle is 00°-30°, and the design wavelength is 4 μm. After the optimization at 7zoom positions by using the design tools Code V, the root-mean-square (RMS) spot size is reduced to approximately 0.99 to 1.48 times the diffraction limit. The design results show that the performances of the conformal optical systems can be greatly improved by the combination of the static correction and the dynamic correction.

  17. A Contrast Transfer Function approach for image calculations in standard and aberration-corrected LEEM and PEEM

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, S.M., E-mail: schramm@physics.leidenuniv.nl [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); Pang, A.B. [School of Physics and Electronic Information, Huaibei Normal University, Huaibei, Anhui 235000 (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Altman, M.S. [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Tromp, R.M. [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States)

    2012-04-15

    We introduce an extended Contrast Transfer Function (CTF) approach for the calculation of image formation in low energy electron microscopy (LEEM) and photo electron emission microscopy (PEEM). This approach considers aberrations up to fifth order, appropriate for image formation in state-of-the-art aberration-corrected LEEM and PEEM. We derive Scherzer defocus values for both weak and strong phase objects, as well as for pure amplitude objects, in non-aberration-corrected and aberration-corrected LEEM. Using the extended CTF formalism, we calculate contrast and resolution of one-dimensional and two-dimensional pure phase, pure amplitude, and mixed phase and amplitude objects. PEEM imaging is treated by adapting this approach to the case of incoherent imaging. Based on these calculations, we show that the ultimate resolution in aberration-corrected LEEM is about 0.5 nm, and in aberration-corrected PEEM about 3.5 nm. The aperture sizes required to achieve these ultimate resolutions are precisely determined with the CTF method. The formalism discussed here is also relevant to imaging with high resolution transmission electron microscopy. -- Highlights: Black-Right-Pointing-Pointer We introduce an extended Contrast Transfer Function (CTF) approach for the calculation of image formation in low energy electron microscopy (LEEM) and photo electron emission microscopy (PEEM). Black-Right-Pointing-Pointer We consider aberrations up to fifth order, appropriate for image formation in state-of-the-art aberration-corrected LEEM and PEEM. Black-Right-Pointing-Pointer We derive Scherzer defocus values for both weak and strong phase objects, as well as for pure amplitude objects, in non-aberration-corrected and aberration-corrected LEEM. Black-Right-Pointing-Pointer We show that the ultimate resolution in aberration-corrected LEEM is about 0.5 nm, and in aberration-corrected PEEM about 3.5 nm.

  18. Characterization of deformable mirrors for spherical aberration correction in optical sectioning microscopy.

    Science.gov (United States)

    Shaw, Michael; Hall, Simon; Knox, Steven; Stevens, Richard; Paterson, Carl

    2010-03-29

    In this paper we describe the wavefront aberrations that arise when imaging biological specimens using an optical sectioning microscope and generate simulated wavefronts for a planar refractive index mismatch. We then investigate the capability of two deformable mirrors for correcting spherical aberration at different focusing depths for three different microscope objective lenses. Along with measurement and analysis of the mirror influence functions we determine the optimum mirror pupil size and number of spatial modes included in the wavefront expansion and we present measurements of actuator linearity and hysteresis. We find that both mirrors are capable of correcting the wavefront aberration to improve imaging and greatly extend the depth at which diffraction limited imaging is possible.

  19. Exploring the depth range for three-dimensional laser machining with aberration correction.

    Science.gov (United States)

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  20. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2014-09-01

    The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.

  1. Aberration-corrected imaging of active sites on industrial catalyst nanoparticles

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Chang, L-Y; Hetherington, CJD;

    2007-01-01

    Picture perfect: Information about the local topologies of active sites on commercial nanoparticles can be gained with atomic resolution through spherical-aberration-corrected transmission electron microscopy (TEM). A powder of Pt nanoparticles on carbon black was examined with two advanced TEM t...

  2. Automatic low-order aberration correction based on geometry optics: simulations

    Science.gov (United States)

    Yu, Xin; Dong, Lizhi; Liu, Yong; Yang, Ping; Tang, Guomao; Xu, Bing

    2016-10-01

    The slab laser is a promising architecture to achieve high beam quality and high power. By propagating the laser beams in zigzag geometries, the temperature gradient in the gain medium can be well averaged, and the beam quality in this direction can be excellent. However, the temperature gradient in the non-zigzag direction is not compensated, resulting in aberrations in this direction which lead to poorer beam quality. Among the overall aberrations, the main contributors are two low-order aberrations: astigmatism and defocus. These aberrations will magnify beam divergence angle and degrade beam quality. If the beam divergence angles in both directions are almost zero, the astigmatism and defocus are well corrected. Besides, the output beams of slab lasers are generally in a rectangular aperture with high aspect ratio (normally 1:10), which need to be reshaped into square in many applications. In this paper, a new method is proposed to correct low-order aberrations and reshape the beams of slab lasers. Three lenses are adapted, one is a spherical lens and the others are cylindrical lenses. These lenses work as a beam shaping system, which converts the beam from rectangular into square and the low-order aberrations are compensated simultaneously. Two wavefront sensors are used to detect input and output beam parameters. The initial size of the beam is 4mm×20mm, and peak to valley (PV) value of the wavefront is several tens of microns. Simulation results show that after correction, the dimension becomes 40mm×40mm, and peak to valley (PV) value of the wavefront is less than 1microns.

  3. Examining the Effects of Chromatic Aberration, Object Distance, and Eye Shape on Image-Formation in the Mirror-Based Eyes of the Bay Scallop Argopecten irradians.

    Science.gov (United States)

    Speiser, Daniel I; Gagnon, Yakir Luc; Chhetri, Raghav K; Oldenburg, Amy L; Johnsen, Sönke

    2016-11-01

    The eyes of scallops form images using a concave spherical mirror and contain two separate retinas, one layered on top of the other. Behavioral and electrophysiological studies indicate that the images formed by these eyes have angular resolutions of about 2°. Based on previous ray-tracing models, it has been thought that the more distal of the two retinas lies near the focal point of the mirror and that the proximal retina, positioned closer to the mirror at the back of the eye, receives light that is out-of-focus. Here, we propose three mechanisms through which both retinas may receive focused light: (1) chromatic aberration produced by the lens may cause the focal points for longer and shorter wavelengths to fall near the distal and proximal retinas, respectively; (2) focused light from near and far objects may fall on the distal and proximal retinas, respectively; and (3) the eyes of scallops may be dynamic structures that change shape to determine which retina receives focused light. To test our hypotheses, we used optical coherence tomography (OCT), a method of near-infrared optical depth-ranging, to acquire virtual cross-sections of live, intact eyes from the bay scallop Argopecten irradians Next, we used a custom-built ray-tracing model to estimate the qualities of the images that fall on an eye's distal and proximal retinas as functions of the wavelengths of light entering the eye (400-700 nm), object distances (0.01-1 m), and the overall shape of the eye. When we assume 550 nm wavelength light and object distances greater than 0.01 m, our model predicts that the angular resolutions of the distal and proximal retinas are 2° and 7°, respectively. Our model also predicts that neither chromatic aberration nor differences in object distance lead to focused light falling on the distal and proximal retinas simultaneously. However, if scallops can manipulate the shapes of their eyes, perhaps through muscle contractions, we speculate that they may be able

  4. Chromosome aberrations, micronucleus and sperm head abnormalities in mice treated with natamycin, [corrected] a food preservative.

    Science.gov (United States)

    Rasgele, Pinar Goc; Kaymak, Fisun

    2010-03-01

    Natamycin [corrected] is used as preservative in foods. The genotoxic effects of the food preservative natamycin [corrected] were evaluated using chromosome aberrations and micronucleus test in bone marrow cells and sperm head abnormality assays in mice. Blood samples were taken from mice and levels of total testosterone in serum were also determined. Natamycin [corrected] was intraperitoneally (ip) injected at 200, 400 and 800 mg/kg. Natamycin [corrected] did not induce chromosome aberrations but significantly increased the number of micronucleated polychromatic erythrocytes in bone marrow and sperm head abnormalities at all concentrations and treatment periods. It also decreased MI at all concentrations for 6, 12 and 24h treatment periods. Natamycin [corrected] decreased PCE/NCE ratio at all concentrations for 48h in female mice, for 24 and 48h treatment periods in male mice. At the 800 mg/kg concentration, natamycin [corrected] decreased PCE/NCE ratio for 24 and 72h in female mice. A dose dependent increase was observed in the percentage of sperm head abnormalities. The levels of serum testosterone decreased dose-dependently. The obtained results indicate that natamycin [corrected] is not clastogenic, but it is aneugenic in mice bone marrow and it is a potential germ cell mutagen in sperm cells.

  5. Time-resolved magnetic imaging in an aberration-corrected, energy-filtered photoemission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, F., E-mail: fl.nickel@fz-juelich.de [Peter Grünberg Institut PGI-6 “Electronic Properties”, Research Center Jülich, 52425 Jülich (Germany); Gottlob, D.M. [Peter Grünberg Institut PGI-6 “Electronic Properties”, Research Center Jülich, 52425 Jülich (Germany); Fakultät für Physik und Center for Nanointegration Duisburg-Essen (CeNIDE), Universität Duisburg-Essen, 47048 Duisburg (Germany); Krug, I.P.; Doganay, H.; Cramm, S. [Peter Grünberg Institut PGI-6 “Electronic Properties”, Research Center Jülich, 52425 Jülich (Germany); Kaiser, A.M. [SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin (Germany); Lin, G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Strasse 70, 09107 Chemnitz (Germany); Makarov, D.; Schmidt, O.G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden (Germany); and others

    2013-07-15

    We report on the implementation and usage of a synchrotron-based time-resolving operation mode in an aberration-corrected, energy-filtered photoemission electron microscope. The setup consists of a new type of sample holder, which enables fast magnetization reversal of the sample by sub-ns pulses of up to 10 mT. Within the sample holder current pulses are generated by a fast avalanche photo diode and transformed into magnetic fields by means of a microstrip line. For more efficient use of the synchrotron time structure, we developed an electrostatic deflection gating mechanism capable of beam blanking within a few nanoseconds. This allows us to operate the setup in the hybrid bunch mode of the storage ring facility, selecting one or several bright singular light pulses which are temporally well-separated from the normal high-intensity multibunch pulse pattern. - Highlights: • A new time-resolving operation mode in photoemission electron microscopy is shown. • Our setup works within an energy-filtered, aberration-corrected PEEM. • A new gating system for bunch selection using synchrotron radiation is developed. • An alternative magnetic excitation system is developed. • First tr-imaging using an energy-filtered, aberration-corrected PEEM is shown.

  6. Aberration and boresight error correction for conformal windows using tilted and decentered fixed correctors

    Science.gov (United States)

    Zhao, Chunzhu; Mao, Shan

    2016-10-01

    A static solution to aberrations and boresight error for tilted conformal aircraft windows at different look angles is reported, which is the use of tilted and decentered fixed correctors. The principle of the static solution is discussed, and three tilted and decentered fixed correctors are designed to correct the aberrations and boresight error for a conformal window. The correctors are fixed in position between the conformal window and the gimbaled imaging system, thus requiring no moving parts. The design result shows that the predominant astigmatism introduced by the conformal window is corrected by the tilted and decentered fixed correctors at different look angles. Moreover, the boresight error for the conformal window, as a function of look angle, is also corrected by the correctors. The root mean square wavefront aberration for the final conformal window imaging system is less than 0.2 wave across the full field of regard on the visible spectrum, and the boresight error is less than 0.5' across the full field of regard.

  7. A proposal for the holographic correction of incoherent aberrations by tilted reference waves

    Energy Technology Data Exchange (ETDEWEB)

    Röder, Falk, E-mail: Falk.Roeder@Triebenberg.de; Lubk, Axel

    2015-05-15

    The recently derived general transfer theory for off-axis electron holography provides a new approach for reconstructing the electron wave beyond the conventional sideband information limit. Limited ensemble coherence of the electron beam between object and reference area leads to an attenuation of spatial frequencies of the object exit wave in the presence of aberrations of the objective lens. Concerted tilts of the reference wave under the condition of an invariant object exit wave are proposed to diminish the aberration impact on spatial frequencies even beyond the sideband information limit allowing its transfer with maximum possible contrast. In addition to the theoretical considerations outlined in detail, an experimental proof-of-principle is presented. A fully controlled tilt of the reference wave, however, remains as a promising task for the future. The use of a hologram series with varying reference wave tilt is considered for linearly synthesizing an effective aperture for the transfer into the sideband with broader bandwidth compared to conventional off-axis electron holography allowing us to correct the incoherent aberrations in transmission electron microscopy. Furthermore, tilting a reference wave with respect to a plane wave is expected to be an alternative way for measuring the coherent and incoherent aberrations of a transmission electron microscope. The capability of tilting the reference wave is expected to be beneficial for improving the signal-to-noise ratio in dark-field off-axis electron holography as well. - Highlights: • We examine the use of tilted reference waves in off-axis electron holography. • Generalized holographic transfer theory reveals a selective filtering effect. • We propose the correction of incoherent aberrations by series acquisitions. • For a proof-of-principle, we employ a crystal for tilting the reference wave.

  8. Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects

    Energy Technology Data Exchange (ETDEWEB)

    Lehtinen, Ossi, E-mail: ossi.lehtinen@gmail.com [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany); Geiger, Dorin; Lee, Zhongbo [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany); Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras [Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Kaiser, Ute [Central Facility for Electron Microscopy, Group of Electron Microscopy of Materials Science, University of Ulm, 89081 Ulm (Germany)

    2015-04-15

    Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method, and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe{sub 2} resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects.

  9. Derivative Form of Off-axis Aberration Correction Surface and Its Application in Solar Energy Concentration

    Institute of Scientific and Technical Information of China (English)

    LI Li; CHEN Ying-Tian; HU Sen

    2009-01-01

    By using the derivative method, we obtained the same result with that of the previous work of Chen et al.in 2006.Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al.in 2001.The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray.

  10. Wide aperture piezoceramic deformable mirrors for aberration correction in high-power lasers

    Institute of Scientific and Technical Information of China (English)

    Vadim Samarkin; Alexander Alexandrov; Gilles Borsoni; Takahisa Jitsuno; Pavel Romanov; Aleksei Rukosuev; Alexis Kudryashov

    2016-01-01

    The deformable mirror with the size of 410 mmstacks was developed. The results ×468 mm controlled by the bimorph piezoceramic plates and multilayer piezoceramic of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack–Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm(RMS). The possibility of correction of the aberrations in high-power lasers was numerically demonstrated.

  11. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics.

    Science.gov (United States)

    Dong, Bing; Li, Yan; Han, Xin-Li; Hu, Bin

    2016-09-02

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10(-5) in optimized correction and is 1.427 × 10(-5) in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method.

  12. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics

    Science.gov (United States)

    Dong, Bing; Li, Yan; Han, Xin-li; Hu, Bin

    2016-01-01

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10−5 in optimized correction and is 1.427 × 10−5 in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method. PMID:27598161

  13. Performance analysis of adaptive fiber laser array propagating in atmosphere with correction of high order aberrations in sub-aperture

    Science.gov (United States)

    Li, Feng; Geng, Chao; Li, Xinyang; Qiu, Qi

    2016-10-01

    Recently developed adaptive fiber laser array technique provides a promising way incorporating aberrations correction with laser beams transmission. Existing researches are focused on sub-aperture low order aberrations (pistons and tips/tilts) compensation and got excellent correction results for weak and moderate turbulence in short range. While such results are not adequate for future laser applications which face longer range and stronger turbulence. So sub-aperture high aberrations compensation is necessary. Relationship between corrigible orders of sub-aperture aberrations and far-field metrics as power-in-the-bucket (PIB) and Strehl ratio is investigated with numeric simulation in this paper. Numerical investigation results shows that increment in array number won't result in effective improvement of the far-field metric if sub-aperture size is fixed. Low order aberrations compensation in sub-apertures gets its best performances only when turbulence strength is weak. Pistons compensation becomes invalid and higher order aberrations compensation is necessary when turbulence gets strong enough. Cost functions of the adaptive fiber laser array with high order aberrations correction in sub-apertures are defined and the optimum corrigible orders are discussed. Results shows that high order (less than first ten Zernike orders) compensation is acceptable where balance between increment of the far-field metric and the cost and complexity of the system could be reached.

  14. Sensor-less aberration correction in optical imaging systems using blind optimization

    Science.gov (United States)

    Avanaki, Mohammad R. N.; Mazraeh Khoshki, R.; Hojjatoleslami, S. A.; Podoleanu, A. Gh.

    2012-02-01

    The imperfection of optical devices in an optical imaging system deteriorates wavefront which results in aberration. This reduces the optical signal to noise ratio of the imaging system and the quality of the produced images. Adaptive optics composed of wavefront sensor (WFS) and deformable mirror (DM) is a straightforward solution for this problem. The need for a WFS in an AO system, raises the cost of the overall system, and there are also instances when they cannot be used, such as in microscopy. Moreover stray reflections from lens surfaces affect the performance of the WFS. In this paper, we describe a blind optimization technique with an in-expensive electronics without using the WFS to correct the aberration in order to achieve better quality images. The correction system includes an electromagnetic DM from Imagine, Mirao52d, with 52 actuators which are controlled by particle swarm optimization (PSO) algorithm. The results of the application of simulated annealing (SA), and genetic algorithm (GA) techniques that we have implemented in the sensor-less AO are used for comparison.

  15. Phase aberration correction by multi-stencils fast marching method using sound speed image in ultrasound computed tomography

    Science.gov (United States)

    Qu, Xiaolei; Azuma, Takashi; Lin, Hongxiang; Imoto, Haruka; Tamano, Satoshi; Takagi, Shu; Umemura, Shin-Ichiro; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-04-01

    Reflection image from ultrasound computed tomography (USCT) system can be obtained by synthetic aperture technique, however its quality is decreased by phase aberration caused by inhomogeneous media. Therefore, phase aberration correction is important to improve image quality. In this study, multi-stencils fast marching method (MSFMM) is employed for phase correction. The MSFMM is an accurate and fast solution of Eikonal equation which considers the refraction. The proposed method includes two steps. First, the MSFMM is used to compute sound propagation time from each element to each image gird point using sound speed image of USCT. Second, synthetic aperture technique is employed to obtain reflection image using the computed propagation time. To evaluate the proposed method, both numerical simulation and phantom experiment were conducted. With regard to numerical simulation, both quantitative and qualitative comparisons between reflection images with and without phase aberration correction were given. In the quantitative comparison, the diameters of point spread function (PSF) in reflection images of a two layer structure were presented. In the qualitative comparison, reflection images of simple circle and complex breast modes with phase aberration correction show higher quality than that without the correction. In respect to phantom experiment, a piece of breast phantom with artificial glandular structure inside was scanned by a USCT prototype, and the artificial glandular structure is able to be visible more clearly in the reflection image with phase aberration correction than in that without the correction. In this study, a phase aberration correction method by the MSFMM are proposed for reflection image of the USCT.

  16. Optimum aberration coefficients for recording high-resolution off-axis holograms in a Cs-corrected TEM

    Energy Technology Data Exchange (ETDEWEB)

    Linck, Martin, E-mail: linck@ceos-gmbh.de [CEOS GmbH, Englerstr. 28, D-69126 Heidelberg (Germany)

    2013-01-15

    Amongst the impressive improvements in high-resolution electron microscopy, the Cs-corrector also has significantly enhanced the capabilities of off-axis electron holography. Recently, it has been shown that the signal above noise in the reconstructable phase can be significantly improved by combining holography and hardware aberration correction. Additionally, with a spherical aberration close to zero, the traditional optimum focus for recording high-resolution holograms ('Lichte's defocus') has become less stringent and both, defocus and spherical aberration, can be selected freely within a certain range. This new degree of freedom can be used to improve the signal resolution in the holographically reconstructed object wave locally, e.g. at the atomic positions. A brute force simulation study for an aberration corrected 200 kV TEM is performed to determine optimum values for defocus and spherical aberration for best possible signal to noise in the reconstructed atomic phase signals. Compared to the optimum aberrations for conventional phase contrast imaging (NCSI), which produce 'bright atoms' in the image intensity, the resulting optimum values of defocus and spherical aberration for off-axis holography enable 'black atom contrast' in the hologram. However, they can significantly enhance the local signal resolution at the atomic positions. At the same time, the benefits of hardware aberration correction for high-resolution off-axis holography are preserved. It turns out that the optimum is depending on the object and its thickness and therefore not universal. -- Highlights: Black-Right-Pointing-Pointer Optimized aberration parameters for high-resolution off-axis holography. Black-Right-Pointing-Pointer Simulation and analysis of noise in high-resolution off-axis holograms. Black-Right-Pointing-Pointer Improving signal resolution in the holographically reconstructed phase shift. Black-Right-Pointing-Pointer Comparison of &apos

  17. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Van Boxem, Ruben [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Mazilu, Michael [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS (United Kingdom); Verbeeck, Jo, E-mail: jo.verbeeck@uantwerpen.be [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2015-04-15

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods.

  18. Dark-field electron holography for the mapping of strain in nanostructures: correcting artefacts and aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hytch, M J; Houdellier, F; Snoeck, E; Huee, F, E-mail: hytch@cemes.f [CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France)

    2010-07-01

    We present details of the new electron holographic dark-field technique (HoloDark) for mapping strain in nanostructures. A diffracted beam emanating from an unstrained region of crystal is interfered (with the aid of an electrostatic biprism) with a diffracted beam from the strained region of interest. Geometric phase analysis (GPA) of the holographic fringes determines the relative deformation of the two crystalline lattices. Strain can be measured to high precision, with nanometre spatial resolution and for micron fields of view. Experiments are carried out on the SACTEM-Toulouse, a Tecnai F20 (FEI) equipped with imaging aberration corrector (CEOS), field-emission gun and rotatable biprism (FEI). We operate the microscope in free-lens control with the main objective lens switched off and using the corrector transfer lenses as a Lorentz lens. We will present measurements of strain in test nanostructures and show how artefacts from thickness variations can be removed. Finally, we show our first results using a recently developed aberration-corrected Lorentz mode (CEOS).

  19. Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope.

    Science.gov (United States)

    Wang, Peng; Behan, Gavin; Kirkland, Angus I; Nellist, Peter D; Cosgriff, Eireann C; D'Alfonso, Adrian J; Morgan, Andrew J; Allen, Leslie J; Hashimoto, Ayako; Takeguchi, Masaki; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2011-06-01

    Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored.

  20. A 45-element continuous facesheet surface micromachined deformable mirror for optical aberration correction

    Directory of Open Access Journals (Sweden)

    Weimin Wang

    2014-02-01

    Full Text Available A 45-element continuous facesheet surface micromachined deformable mirror (DM is presented and is fabricated using the PolyMUMPs multi-user micro-electro-mechanical system processes. The effects of the structural parameters on the characteristics of the DM, such as its stroke, frequency and actuator coupling, are analyzed. In addition, the DM design has also been verified through experimental testing. This DM prototype has a surface figure of 0.5 μm and a fill factor of 95%. The DM can provide a 0.6 μm stroke with 5.9% actuator coupling. A static aberration correction based on this DM is also demonstrated, which acts as a reference for the potential adaptive optics (AO applications of the device.

  1. Perfect X-ray focusing via fitting corrective glasses to aberrated optics.

    Science.gov (United States)

    Seiboth, Frank; Schropp, Andreas; Scholz, Maria; Wittwer, Felix; Rödel, Christian; Wünsche, Martin; Ullsperger, Tobias; Nolte, Stefan; Rahomäki, Jussi; Parfeniukas, Karolis; Giakoumidis, Stylianos; Vogt, Ulrich; Wagner, Ulrich; Rau, Christoph; Boesenberg, Ulrike; Garrevoet, Jan; Falkenberg, Gerald; Galtier, Eric C; Ja Lee, Hae; Nagler, Bob; Schroer, Christian G

    2017-03-01

    Due to their short wavelength, X-rays can in principle be focused down to a few nanometres and below. At the same time, it is this short wavelength that puts stringent requirements on X-ray optics and their metrology. Both are limited by today's technology. In this work, we present accurate at wavelength measurements of residual aberrations of a refractive X-ray lens using ptychography to manufacture a corrective phase plate. Together with the fitted phase plate the optics shows diffraction-limited performance, generating a nearly Gaussian beam profile with a Strehl ratio above 0.8. This scheme can be applied to any other focusing optics, thus solving the X-ray optical problem at synchrotron radiation sources and X-ray free-electron lasers.

  2. Influence of adaptive-optics ocular aberration correction on visual acuity at different luminances and contrast polarities.

    Science.gov (United States)

    Marcos, Susana; Sawides, Lucie; Gambra, Enrique; Dorronsoro, Carlos

    2008-10-06

    We evaluated the visual benefit of correcting astigmatism and high-order aberrations with adaptive optics (AO) on visual acuity (VA) measured at 7 different luminances (ranging from 0.8 to 50 cd/m(2)) and two contrast polarities (black letters on white background, BoW, and white letters on black background, WoB) on 7 subjects. For the BoW condition, VA increased with background luminance in both natural and AO-corrected conditions, and there was a benefit of AO correction at all luminances (by a factor of 1.29 on average across luminances). For WoB VA increased with foreground luminance but decreased for the highest luminances. In this reversed polarity condition AO correction increased VA by a factor of 1.13 on average and did not produce a visual benefit at high luminances. The improvement of VA (averaged across conditions) was significantly correlated (p = 0.04) with the amount of corrected aberrations (in terms of Strehl ratio). The improved performance with WoB targets with respect to BoW targets is decreased when correcting aberrations, suggesting a role of ocular aberrations in the differences in visual performance between contrast polarities.

  3. Nanostructural and Chemical Characterization of Supported Metal Oxide Catalysts by Aberration Corrected Analytical Electron Microscopy

    Science.gov (United States)

    Zhou, Wu

    In this thesis, aberration corrected STEM imaging and chemical analysis techniques have been extensively applied in the structural and chemical characterization of supported tungsten oxide catalysts in an attempt to reveal the structure-activity relationships at play in these catalyst systems. The supported WO3/ZrO2 solid acid catalyst system is a major focal point of this thesis, and detailed aberration-corrected STEM-HAADF imaging studies were performed on a systematic set of catalysts showing different level of catalytic performance. The nature of the catalytically most active WOx species was identified by correlating structural information, obtained from STEM-HAADF and in-situ optical spectroscopy studies, with catalytic testing results. Specifically, ˜1nm distorted Zr-WOx mixed oxide clusters were identified to be the most active species for both the methanol dehydration and n-pentane isomerization reactions in the WO3/ZrO2 catalyst system. The use of amorphous zirconia as a precursor support material makes it much easier to extract and incorporate Zr cations into the surface WOx clusters during calcination. The calcination temperature was also identified to also play an important role in the formation of these most active Zr-WOx clusters. When the calcination temperature is comparable to or higher than the 896K Huttig temperature of ZrO2 (at which surface ZrO x species have sufficient mobility to agglomerate and sinter), the chance for successful surface WOx and ZrOx intermixing is significantly increased. Based on this perceived structure-activity relationship, several new catalyst synthesis strategies were developed in an attempt to optimize the catalytic performance of WOx-based catalysts. We have demonstrated in Chapter 3 that co-impregnation of WOx and ZrOx precursors onto an inactive model WO3/ZrO2 catalyst, followed by a calcination treatment above the 896K Huttig temperature of ZrO 2, promotes the surface diffusion of ZrO2 and intermixing of Zr

  4. First experimental proof for aberration correction in XPEEM: Resolution, transmission enhancement, and limitation by space charge effects

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Th., E-mail: schmidtt@fhi-berlin.mpg.de [Fritz Haber Institute of the Max Planck Society, Department of Chemical Physics, Faradayweg 4-6, D-14195 Berlin (Germany); Sala, A.; Marchetto, H. [Fritz Haber Institute of the Max Planck Society, Department of Chemical Physics, Faradayweg 4-6, D-14195 Berlin (Germany); Umbach, E. [Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany); Freund, H.-J. [Fritz Haber Institute of the Max Planck Society, Department of Chemical Physics, Faradayweg 4-6, D-14195 Berlin (Germany)

    2013-03-15

    The positive effect of double aberration correction in x-ray induced Photoelectron Emission Microscopy (XPEEM) has been successfully demonstrated for both, the lateral resolution and the transmission, using the Au 4f XPS peak for element specific imaging at a kinetic energy of 113 eV. The lateral resolution is improved by a factor of four, compared to a non-corrected system, whereas the transmission is enhanced by a factor of 5 at a moderate resolution of 80 nm. With an optimized system setting, a lateral resolution of 18 nm could be achieved, which is up to now the best value reported for energy filtered XPEEM imaging. However, the absolute resolution does not yet reach the theoretical limit of 2 nm, which is due to space charge limitation. This occurs along the entire optical axis up to the contrast aperture. In XPEEM the pulsed time structure of the exciting soft x-ray light source causes a short and highly intense electron pulse, which results in an image blurring. In contrast, the imaging with elastically reflected electrons in the low energy electron microscopy (LEEM) mode yields a resolution clearly below 5 nm. Technical solutions to reduce the space charge effect in an aberration-corrected spectro-microscope are discussed. - Highlights: ► First successful double aberration correction in XPEEM. ► Improvement of resolution and transmission by aberration correction. ► Lateral resolution of 18 nm in energy filtered XPEEM is the best up to now reported value. ► First investigation of space charge effects in aberrations corrected PEEM.

  5. Model-based aberration correction in a closed-loop wavefront-sensor-less adaptive optics system

    NARCIS (Netherlands)

    Song, H.; Fraanje, R.; Schitter, G.; Kroese, H.; Vdovin, G.; Verhaegen, M.

    2010-01-01

    In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront

  6. Aberration-corrected electron microscopy of MnAs and As nanocrystals and voids in annealed (Ga,Mn)As

    DEFF Research Database (Denmark)

    Kovács, András; Kasama, Takeshi; Sadowski, J.;

    2011-01-01

    Aberration-corrected transmission electron microscopy is used to study voids and nano-crystalline MnAs and As phases formed during the annealing of Mn-doped GaAs. The effects of defocus and inner annular dark-field detector semi-angle on contrast of the nanocrystals are discussed....

  7. Optimizing Chromatic Coupling Measurement in the LHC

    CERN Document Server

    Persson, Tobias

    2016-01-01

    Optimizing chromatic coupling measurement in the LHC Chromatic coupling introduces a dependency of transverse coupling with energy. LHC is equipped with skew sextupoles to compensate the possible adverse effects of chromatic coupling. In 2012 a beam-based correction was calculated and applied successfully for the fist time. However, the method used to reconstruct the chromatic coupling was dependent on stable tunes and equal chromaticities between the horizontal and vertical planes. In this article an improved method to calculate the chromatic coupling without these constraints is presented.

  8. Practical spatial resolution of electron energy loss spectroscopy in aberration corrected scanning transmission electron microscopy.

    Science.gov (United States)

    Shah, A B; Ramasse, Q M; Wen, J G; Bhattacharya, A; Zuo, J M

    2011-08-01

    The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using chemically modulated 2×(LaMnO(3))/2×(SrTiO(3)) and 2×(SrVO(3))/2×(SrTiO(3)) superlattices by measuring the full width at half maxima (FWHM) of integrated Ti M(2,3), Ti L(2,3), V L(2,3), Mn L(2,3), La N(4,5), La N(2,3) La M(4,5) and Sr L(3) edges over the superlattices. The EELS signals recorded using large collection angles are peaked at atomic columns. The FWHM of the EELS profile, obtained by curve-fitting, reveals a systematic trend with the energy loss for the Ti, V, and Mn edges. However, the experimental FWHM of the Sr and La edges deviates significantly from the observed experimental tendency.

  9. Aberration Corrected Scanning Transmission Electron Microscopy of (Ca , Sr)Fe2O5 Brownmillerite superlattices

    Science.gov (United States)

    Mukherjee, Debangshu; Stone, Greg; Moon, Eun Ju; Young, Joshua; Gopalan, Venkatraman; Rondinelli, James; May, Steven; Alem, Nasim

    The brownmillerite phase A2B2O5 consists of ordered oxygen vacancies in alternate perovskite layers forming chiral tetrahedral chains. The handedness of these tetrahedral chains control the polarization of the structure. The current study focuses on 1-1 brownmillerite superlattices grown on a SrTiO3 substrates using molecular beam epitaxy. The B-site in this structure is iron throughout the superlattice film, while the A-site alternates between calcium and strontium in the superlattice layers. In this study, we use atomic resolution aberration corrected scanning transmission electron microscopy (STEM) to investigate the structure and chemistry of the film-substrate interface as well as the chemical structure of the superlattice. Atom positions are determined to measure displacement vectors of A-site cations in the superlattice structure. D.M., G.A.S., V.G. and N.A. were supported by the National Science Foundation under Grant No. DMR-1420620. E.J.M. and S.J.M. were supported by the National Science Foundation under Grant No. DMR-1151649.

  10. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K; Boyes, E D; Gai, P L [York JEOL Nanocentre (United Kingdom); Shiju, N R; Brown, D R, E-mail: pgb500@york.ac.u [Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield, HD1 3DH (United Kingdom)

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  11. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Science.gov (United States)

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  12. Molecular Docking and Aberration-Corrected STEM of Palladium Nanoparticles on Viral Templates

    Directory of Open Access Journals (Sweden)

    Liliana Carreño-Fuentes

    2016-08-01

    Full Text Available Viral templates are highly versatile biotemplates used for the synthesis of nanostructured materials. Rotavirus VP6 self-assembles into nanotubular hollow structures with well-defined diameters and variable lengths, serving as a nucleic acid-free biotemplate to synthesize metal nanoparticles of controlled size, shape, and orientation. Molecular docking simulations show that exposed residues (H173-S240-D242 and N200-N310 of VP6 have the ability to specifically bind Pd(II ions, which serve as nucleation sites for the growth and stabilization of palladium nanoclusters. Using VP6 nanotubes as biotemplates allows for obtaining small Pd particles of 1–5 nm in diameter. Advanced electron microscopy imaging and characterization through ultra-high-resolution field-emission scanning electron microscopy (UHR-FE-SEM and spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM at a low voltage dose (80 kV reveals, with high spatial resolution, the structure of Pd nanoparticles attached to the macromolecular biotemplates.

  13. Fabrication of polarization-independent waveguides deeply buried in lithium niobate crystal using aberration-corrected femtosecond laser direct writing

    Science.gov (United States)

    Wang, Peng; Qi, Jia; Liu, Zhengming; Liao, Yang; Chu, Wei; Cheng, Ya

    2017-01-01

    Writing optical waveguides with femtosecond laser pulses provides the capability of forming three-dimensional photonic circuits for manipulating light fields in both linear and nonlinear manners. To fully explore this potential, large depths of the buried waveguides in transparent substrates are often desirable to facilitate achieving vertical integration of waveguides in a multi-layer configuration, which, however, is hampered by rapidly degraded axial resolution caused by optical aberration. Here, we show that with the correction of the spherical aberration, polarization-independent waveguides can be inscribed in a nonlinear optical crystal lithium niobate (LN) at depths up to 1400 μm, which is more than one order of magnitude deeper than the waveguides written with aberration uncorrected femtosecond laser pulses. Our technique is beneficial for applications ranging from miniaturized nonlinear light sources to quantum information processing. PMID:28112246

  14. Chromosome therapy. Correction of large chromosomal aberrations by inducing ring chromosomes in induced pluripotent stem cells (iPSCs).

    Science.gov (United States)

    Kim, Taehyun; Bershteyn, Marina; Wynshaw-Boris, Anthony

    2014-01-01

    The fusion of the short (p) and long (q) arms of a chromosome is referred to as a "ring chromosome." Ring chromosome disorders occur in approximately 1 in 50,000-100,000 patients. Ring chromosomes can result in birth defects, mental disabilities, and growth retardation if additional genes are deleted during the formation of the ring. Due to the severity of these large-scale aberrations affecting multiple contiguous genes, no possible therapeutic strategies for ring chromosome disorders have so far been proposed. Our recent study (Bershteyn et al.) using patient-derived fibroblast lines containing ring chromosomes, found that cellular reprogramming of these fibroblasts into induced pluripotent stem cells (iPSCs) resulted in the cell-autonomous correction of the ring chromosomal aberration via compensatory uniparental disomy (UPD). These observations have important implications for studying the mechanism of chromosomal number control and may lead to the development of effective therapies for other, more common, chromosomal aberrations.

  15. Fabrication of polarization-independent waveguides deeply buried in crystal using aberration-corrected femtosecond laser direct writing

    CERN Document Server

    Wang, Peng; Liu, Zhengming; Liao, Yang; Chu, Wei; Cheng, Ya

    2016-01-01

    Writing optical waveguides with femtosecond laser pulses provides the capability of forming three-dimensional photonic circuits for manipulating light fields in both linear and nonlinear manners. To fully explore this potential, large depths of the buried waveguides in transparent substrates are often desirable to facilitate achieving vertical integration of waveguides in a multi-layer configuration, which, however, is hampered by rapidly degraded axial resolution caused by optical aberration. Here, we show that with the correction of the spherical aberration, polarization-independent waveguides can be inscribed in a nonlinear optical crystal lithium niobate (LN) at depths up to 1.4 mm, which is more than one order of magnitude deeper than the waveguides written with aberration uncorrected femtosecond laser pulses. Our technique is beneficial for applications ranging from miniaturized nonlinear light sources to quantum information processing.

  16. Optical study on the vision correction and supernormal vision based on the wave-front aberrations of human eye

    Institute of Scientific and Technical Information of China (English)

    MU GuoGuang; WANG ZhaoQi; LIU YongJi; QUAN Wei; WANG Yang; WANG Wei

    2007-01-01

    In this paper we present the recent research results in the field of vision correction and supernormal vision according to the actual measurements of the wave-front aberrations and the corneal surface topography, the clinical detection of the visual function and the laser corneal refractive surgery, and the optimization of the optical system. These include the features of the aberrations of human eye with different pupil sizes, different fields of view and temporal accommodation, the influence of the polychromatic illumination of the visible wavelength on the supernormal vision,and the effect of the existing laser corneal refractive surgery on the wave-front aberrations of the eye. It is shown that the wave-front aberration of human eye is of temporal variation and of synthesis with multi impact factors. To achieve supernormal vision, an optimum engineering data for the customized laser corneal surgery should be firstly acquired, which may involve the dynamic free-form optical surface. Although the myopia can be corrected by the laser in situ keratomileusis (LASlK) in a certain degree, it brings about negative effects under scotopic conditions.

  17. Optical study on the vision correction and supernormal vision based on the wave-front aberrations of human eye

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper we present the recent research results in the field of vision correction and supernormal vision according to the actual measurements of the wave-front aberrations and the corneal surface topography,the clinical detection of the visual function and the laser corneal refractive surgery,and the optimization of the optical system. These include the features of the aberrations of human eye with different pupil sizes,different fields of view and temporal accommodation,the influence of the polychromatic illumination of the visible wavelength on the supernormal vision,and the effect of the existing laser corneal refractive surgery on the wave-front ab-errations of the eye. It is shown that the wave-front aberration of human eye is of temporal variation and of synthesis with multi impact factors. To achieve super-normal vision,an optimum engineering data for the customized laser corneal sur-gery should be firstly acquired,which may involve the dynamic free-form optical surface. Although the myopia can be corrected by the laser in situ keratomileusis(LASIK) in a certain degree,it brings about negative effects under scotopic condi-tions.

  18. Aberration correction for transcranial photoacoustic tomography of primates employing adjunct image data

    Science.gov (United States)

    Huang, Chao; Nie, Liming; Schoonover, Robert W.; Guo, Zijian; Schirra, Carsten O.; Anastasio, Mark A.; Wang, Lihong V.

    2012-06-01

    A challenge in photoacoustic tomography (PAT) brain imaging is to compensate for aberrations in the measured photoacoustic data due to their propagation through the skull. By use of information regarding the skull morphology and composition obtained from adjunct x-ray computed tomography image data, we developed a subject-specific imaging model that accounts for such aberrations. A time-reversal-based reconstruction algorithm was employed with this model for image reconstruction. The image reconstruction methodology was evaluated in experimental studies involving phantoms and monkey heads. The results establish that our reconstruction methodology can effectively compensate for skull-induced acoustic aberrations and improve image fidelity in transcranial PAT.

  19. Correction of cell-induced optical aberrations in a fluorescence fluctuation microscope

    CERN Document Server

    Leroux, Charles-Edouard; Wang, Irène; Delon, Antoine

    2014-01-01

    We describe the effect of optical aberrations on fluorescence fluctuations microscopy (FFM), when focusing through a single living cell. FFM measurements are performed in an aqueous fluorescent solution and prove to be a highly sensitive tool to assess the optical aberrations introduced by the cell. We demonstrate an adaptive optics (AO) system to remove the aberration-related bias in the FFM measurements. Our data show that AO is not only useful when imaging deep in tissues but also when performing FFM measurements through a single cellular layer. This work paves the way for the application of FFM to complex three-dimensional multicellular samples.

  20. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    Energy Technology Data Exchange (ETDEWEB)

    Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki, E-mail: toshiaki.tanigaki.mv@hitachi.com; Shimakura, Tomokazu; Kawasaki, Takeshi; Furutsu, Tadao; Shinada, Hiroyuki; Osakabe, Nobuyuki [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); Müller, Heiko; Haider, Maximilian [Corrected Electron Optical Systems GmbH, Englerstr. 28, D-69126 Heidelberg (Germany); Tonomura, Akira [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-02-16

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

  1. Analysis of the Aberration in Directly-writing Atom Lithography

    Institute of Scientific and Technical Information of China (English)

    LI Chuanwen; CAI Weiquan; WANG Yuzhu

    2000-01-01

    After deriving the approximation solution which describes the motion of neutral atoms in an optical standing wave field with large detuning, the spherical aberration and the chromatic aberration are analyzed and possible methods to reduce these aberrations are discussed.

  2. Aberration corrected and monochromated environmental transmission electron microscopy: challenges and prospects for materials science

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.

    2010-01-01

    The latest generation of environmental transmission electron microscopes incorporates aberration correctors and monochromators, allowing studies of chemical reactions and growth processes with improved spatial resolution and spectral sensitivity. Here, we describe the performance of such an instr...

  3. Spherical Aberration Correction Using Refractive-Diffractive Lenses with an Analytic-Numerical Method

    Directory of Open Access Journals (Sweden)

    Sergio Vázquez-Montiel

    2010-01-01

    Full Text Available We propose an alternative method to design diffractive lenses free of spherical aberration for monochromatic light. Our method allows us to design diffractive lenses with the diffraction structure recorded on the last surface; this surface can be flat or curved with rotation symmetry. The equations that we propose calculate the diffraction profiles for any substratum, for any f-number, and for any position of the object. We use the lens phase coefficients to compensate the spherical aberration. To calculate these coefficients, we use an analytic-numerical method. The calculations are exact, and the optimization process is not required.

  4. Dynamic optical aberration correction with adaptive coded apertures techniques in conformal imaging

    Science.gov (United States)

    Li, Yan; Hu, Bin; Zhang, Pengbin; Zhang, Binglong

    2015-02-01

    Conformal imaging systems are confronted with dynamic aberration in optical design processing. In classical optical designs, for combination high requirements of field of view, optical speed, environmental adaption and imaging quality, further enhancements can be achieved only by the introduction of increased complexity of aberration corrector. In recent years of computational imaging, the adaptive coded apertures techniques which has several potential advantages over more traditional optical systems is particularly suitable for military infrared imaging systems. The merits of this new concept include low mass, volume and moments of inertia, potentially lower costs, graceful failure modes, steerable fields of regard with no macroscopic moving parts. Example application for conformal imaging system design where the elements of a set of binary coded aperture masks are applied are optimization designed is presented in this paper, simulation results show that the optical performance is closely related to the mask design and the reconstruction algorithm optimization. As a dynamic aberration corrector, a binary-amplitude mask located at the aperture stop is optimized to mitigate dynamic optical aberrations when the field of regard changes and allow sufficient information to be recorded by the detector for the recovery of a sharp image using digital image restoration in conformal optical system.

  5. Direct imaging of light elements by annular dark-field aberration-corrected scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318 Leipzig (Germany)

    2014-02-17

    In this report, we show that an annular dark-field detector in an aberration-corrected scanning transmission electron microscope allows the direct observation of light element columns in crystalline lattices. At specific imaging conditions, an enhancement of the intensities of light element columns in the presence of heavy element columns is observed. Experimental results are presented for imaging the nitrogen and carbon atomic columns at the GaN-SiC interface and within the GaN and SiC compounds. The crystal polarity of GaN at the interface is identified. The obtained findings are discussed and are well supported by image simulations.

  6. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    KAUST Repository

    Wang, Hongtao

    2012-01-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. © 2012 The Royal Society of Chemistry.

  7. Pupil-phase optimization for extended-focus, aberration-corrected imaging systems

    Science.gov (United States)

    Prasad, Sudhakar; Pauca, V. Paul; Plemmons, Robert J.; Torgersen, Todd C.; van der Gracht, Joseph

    2004-10-01

    The insertion of a suitably designed phase plate in the pupil of an imaging system makes it possible to encode the depth dimension of an extended three-dimensional scene by means of an approximately shift-invariant PSF. The so-encoded image can then be deblurred digitally by standard image recovery algorithms to recoup the depth dependent detail of the original scene. A similar strategy can be adopted to compensate for certain monochromatic aberrations of the system. Here we consider two approaches to optimizing the design of the phase plate that are somewhat complementary - one based on Fisher information that attempts to reduce the sensitivity of the phase encoded image to misfocus and the other based on a minimax formulation of the sum of singular values of the system blurring matrix that attempts to maximize the resolution in the final image. Comparisons of these two optimization approaches are discussed. Our preliminary demonstration of the use of such pupil-phase engineering to successfully control system aberrations, particularly spherical aberration, is also presented.

  8. Diffractive elements performance in chromatic confocal microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, J; Duque, D; Alean, A; Toledo, M [Grupo de Optica y EspectroscopIa, Centro de Ciencia Basica, Universidad Pontificia Bolivariana. Medellin (Colombia); Meneses, J [Laboratorio de Optica y Tratamiento de Senales, Instituto de Fisica, Universidad Industrial de Santander, Bucaramanga (Colombia); Gharbi, T, E-mail: jgarzonr10@une.net.co [Laboratoire d' Optique P. M. Duffieux, UMR-6603 CNR/Universite de Franche-Comte. 16 route de Gray, 25030 Besancon Cedex (France)

    2011-01-01

    The Confocal Laser Scanning Microscopy (CLSM) has been widely used in the semiconductor industry and biomedicine because of its depth discrimination capability. Subsequent to this technique has been developed in recent years Chromatic Confocal Microscopy. This method retains the same principle of confocal and offers the added advantage of removing the axial movement of the moving system. This advantage is usually accomplished with an optical element that generates a longitudinal chromatic aberration and a coding system that relates the axial position of each point of the sample with the wavelength that is focused on each. The present paper shows the performance of compact chromatic confocal microscope when some different diffractive elements are used for generation of longitudinal chromatic aberration. Diffractive elements, according to the process and manufacturing parameters, may have different diffraction efficiency and focus a specific wavelength in a specific focal position. The performance assessment is carried out with various light sources which exhibit an incoherent behaviour and a broad spectral width.

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

    Science.gov (United States)

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

    2013-05-01

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

  10. Bayesian-based aberration correction and numerical diffraction for improved lensfree on-chip microscopy of biological specimens

    CERN Document Server

    Wong, Alexander; Jin, Chao; Wang, Xiao Yu

    2015-01-01

    Lensfree on-chip microscopy is an emerging imaging technique that can be used to visualize and study biological specimens without the need for imaging lens systems. Important issues that can limit the performance of lensfree on-chip microscopy include interferometric aberrations, acquisition noise, and image reconstruction artifacts. In this study, we introduce a Bayesian-based method for performing aberration correction and numerical diffraction that accounts for all three of these issues to improve the effective numerical aperture (NA) and signal-to-noise ratio (SNR) of the reconstructed microscopic image. The proposed method was experimentally validated using the USAF resolution target as well as real waterborne Anabaena flos-aquae samples, demonstrating improvements in NA by ~25% over the standard method, and improvements in SNR of 2.3 dB and 3.8 dB in the reconstructed image when compared to the reconstructed images produced using the standard method and a maximum likelihood estimation method, respective...

  11. Characterization of surface metallic states in SrTiO{sub 3} by means of aberration corrected electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Santolino, G. [GFMC, Departamento. Física Aplicada III, Universidad Complutense de Madrid, 28040 Madrid (Spain); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6071 (United States); Tornos, J.; Bruno, F.Y.; Cuellar, F.A.; Leon, C.; Santamaría, J. [GFMC, Departamento. Física Aplicada III, Universidad Complutense de Madrid, 28040 Madrid (Spain); Pennycook, S.J [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6071 (United States); Varela, M., E-mail: mvarela@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6071 (United States); GFMC, Departamento. Física Aplicada III, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2013-04-15

    An unusual conducting surface state can be produced in SrTiO{sub 3} substrates by irradiation with Argon ions from a plasma source, at low energy and high doses. The effects of irradiation are analyzed here by atomic force microscopy (AFM) and aberration corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Depth sensitive studies demonstrate the existence of a heavily damaged surface layer and an oxygen vacancy rich layer immediately underneath, both induced during the irradiation process. We find a clear dependence of the Ti oxidation state with the depth, with a very intense Ti{sup 3+} component near the surface. Oxygen vacancies act as n-type doping by releasing electrons into the lattice and producing an insulator-to-metal transition, which explains the unusual metallic behavior of these samples.

  12. The Stanford Nanocharacterization Laboratory (SNL) and Recent Applications of an Aberration-Corrected Environmental Transmission Electron Microscope.

    Science.gov (United States)

    Sinclair, Robert; Kempen, Paul Joseph; Chin, Richard; Koh, Ai Leen

    2014-05-01

    This article describes the establishment, over a period of ten years or so, of a multi-user, institution-wide facility for the characterization of materials and devices at the nano-scale. Emphasis is placed on the type of equipment that we have found to be most useful for our users, and the business strategy that maintains its operations. A central component of our facility is an aberration-corrected environmental transmission electron microscope and its application is summarized in the studies of plasmon energies of silver nanoparticles, the band gap of PbS quantum dots, atomic site occupancy near grain boundaries in yttria stabilized zirconia, the lithiation of silicon nanoparticles, in situ observations on carbon nanotube oxidation and the electron tomography of varicella zoster virus nucleocapsids.

  13. The Stanford Nanocharacterization Laboratory (SNL) and Recent Applications of an Aberration-Corrected Environmental Transmission Electron Microscope**

    Science.gov (United States)

    Sinclair, Robert; Kempen, Paul Joseph; Chin, Richard; Koh, Ai Leen

    2014-01-01

    This article describes the establishment, over a period of ten years or so, of a multi-user, institution-wide facility for the characterization of materials and devices at the nano-scale. Emphasis is placed on the type of equipment that we have found to be most useful for our users, and the business strategy that maintains its operations. A central component of our facility is an aberration-corrected environmental transmission electron microscope and its application is summarized in the studies of plasmon energies of silver nanoparticles, the band gap of PbS quantum dots, atomic site occupancy near grain boundaries in yttria stabilized zirconia, the lithiation of silicon nanoparticles, in situ observations on carbon nanotube oxidation and the electron tomography of varicella zoster virus nucleocapsids. PMID:25364299

  14. In situ observation on hydrogenation of Mg-Ni films using environmental transmission electron microscope with aberration correction

    Science.gov (United States)

    Matsuda, Junko; Yoshida, Kenta; Sasaki, Yukichi; Uchiyama, Naoki; Akiba, Etsuo

    2014-08-01

    In situ transmission electron microscopy (TEM) was performed to observe the hydrogenation of Mg-Ni films in a hydrogen atmosphere of 80-100 Pa. An aberration-corrected environmental TEM with a differential pumping system allows us to reveal the Angstrom-scale structure of the films in the initial stage of hydrogenation: first, nucleation and growth of Mg2NiH4 crystals with a lattice spacing of 0.22 nm in an Mg-rich amorphous matrix of the film occurs within 20 s after the start of the high-resolution observation, then crystallization of MgH2 with a smaller spacing of 0.15 nm happens after approximately 1 min. Our in situ TEM method is also applicable to the analysis of other hydrogen-related materials.

  15. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    Science.gov (United States)

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  16. A speed of sound aberration correction algorithm for curvilinear ultrasound transducers in ultrasound-based image-guided radiotherapy

    Science.gov (United States)

    Fontanarosa, Davide; Pesente, Silvia; Pascoli, Francesco; Ermacora, Denis; Abu Rumeileh, Imad; Verhaegen, Frank

    2013-03-01

    Conventional ultrasound (US) devices use the time of flight (TOF) of reflected US pulses to calculate distances inside the scanned tissues and thus create images. The speed of sound (SOS) is assumed to be constant in all human soft tissues at a generally accepted average value of 1540 m s-1. This assumption is a source of systematic errors up to several millimeters and of image distortion in quantitative US imaging. In this work, an extension of a method recently published by Fontanarosa et al (2011 Med. Phys. 38 2665-73) is presented: the aim is to correct SOS aberrations in three-dimensional (3D) US images in those cases where a spatially co-registered computerized tomography (CT) scan is also available; the algorithm is then applicable to a more general case where the lines of view (LOV) of the US device are not necessarily parallel and coplanar, thus allowing correction also for US transducers other than linear. The algorithm was applied on a multi-modality pelvic US phantom, scanned through three different liquid layers on top of the phantom with different SOS values; the results show that the correction restores a better match between the CT and the US images, reducing the differences to sub-millimeter agreement. Fifteen clinical cases of prostate cancer patients were also investigated: the SOS corrections of prostate centroids were on average +3.1 mm (max + 4.9 mm-min + 1.3 mm). This is in excellent agreement with reports in the literature on differences between measured prostate positions by US and other techniques, where often the discrepancy was attributed to other causes.

  17. On chromatic and geometrical calibration

    DEFF Research Database (Denmark)

    Folm-Hansen, Jørgen

    1999-01-01

    of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... the DLT can be extended with non-linear models of the common lens aberrations/errors some of them caused by manufacturing defects like decentering and thin prism distortion. The relation between a warping and the non-linear defects are shown. The issue of making a good resampling of an image by using...

  18. Holographic Properties of BR-D96N Film and Its Application in Hologram Aberration Correction

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yuan(郑媛); YAO Bao-Li(姚保利); WANG Ying-Li(王英利); MENKE Neimule(门克内木乐); LEI Ming(雷铭); CHEN Guo-Fu(陈国夫); Norbert HAMPP

    2003-01-01

    A biophotochromic material, i.e., genetic mutant bacteriorhodopsin (BR-D96N), was experimentally studied on its holographic recording properties. The saturation absorption curve and the diffraction efficiency curve were measured respectively. As holographic storage application, reflection type polarization holograms were recorded on the BR-D96N film. The 173° configuration between the object and reference beams proves that the spatial resolution of the film is over 6000 lines/mm. By using phase conjugate wave of reference beam as reconstruction beam, the distorted object image introduced by the optical components and the defects in the recording medium can be well corrected.

  19. High-resolution TEM and the application of direct and indirect aberration correction

    DEFF Research Database (Denmark)

    Hetherington, Crispin J.D.; Chang, Lan-Yun Shery; Haigh, Sarah;

    2008-01-01

    or tilt series of images. These direct and indirect methods are complementary, and a combination of the two offers further advantages. Materials characterization has benefitted from the reduced delocalization and higher resolution in the corrected images. It is now possible, for example, to locate atomic...... columns at surfaces to higher accuracy and reliability. This article describes the JEM-2200FS in Oxford, which is equipped with correctors for both the image-forming and probe-forming lenses. Examples of the use of this instrument in the characterization of nanocrystalline catalysts are given together...

  20. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    Science.gov (United States)

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  1. Reply to L.M. Brown et al. "Brief history of the Cambridge STEM aberration correction project and its progeny" in Ultramicroscopy 157, 88 (2015).

    Science.gov (United States)

    Urban, K W; Rose, H

    2016-02-01

    We comment on a Short Communication recently published in Ultramicroscopy in which Brown et al. criticize our description of the time sequence of events in the development of aberration correction systems in electron optics during the 1990s put forward in the introduction to the Ultramicroscopy April 2015 Special Issue. We present an analysis of the published literature furnishing evidence that our description is correct.

  2. Canopy induced aberration correction in airborne electro-optical imaging systems

    Science.gov (United States)

    Harder, James A.; Sprague, Michaelene W.

    2011-11-01

    An increasing number of electro-optical systems are being used by pilots in tactical aircraft. This means that the afore mentioned systems must operate through the aircrafts canopy, unfortunately the canopy functions as a less than ideal lens element in the electro-optical sensor optical path. The canopy serves first and foremost as an aircraft structural component, considerations like minimizing the drag co-efficient and the ability to survive bird strikes take precedence over achieving optimal optical characteristics. This paper describes how the authors characterized the optical characteristics of an aircraft canopy. Families of modulation transfer functions were generated, for various viewing geometries through the canopy and for various electro-optical system entrance pupil diameters. These functions provided us with the means to significantly reduce the effect of the canopy "lens" on the performance of a representative electro-optical system, using an Astigmatic Corrector Lens. A comparison of the electro-optical system performance with and without correction is also presented.

  3. Correção das aberrações oculares nos retratamentos de LASIK personalizado e convencional Correction of ocular aberrations in custom and standard LASIK retreatments

    Directory of Open Access Journals (Sweden)

    Andréia Peltier Urbano

    2009-10-01

    Full Text Available OBJETIVO: Comparar a correção das aberrações oculares nos retratamentos de LASIK personalizado e convencional. MÉTODOS: Foi realizado um estudo prospectivo, randomizado, de 74 olhos de 37 pacientes submetidos ao retratamento de LASIK para correção de miopia e astigmatismo. Cada paciente foi submetido ao retratamento de LASIK personalizado Zyoptix (Bausch & Lomb em um olho e convencional Planoscan (Bausch & Lomb no olho contralateral. Foi comparada a correção das aberrações oculares nos retratamentos personalizado e convencional. RESULTADOS: No sexto mês pós-operatório, os olhos submetidos ao retratamento Zyoptix apresentaram diminuição estatisticamente significativa do defocus, astigmatismo, coma, aberração esférica, segunda ordem, terceira ordem, alta ordem e aberrações totais. Os olhos submetidos ao retratamento Planoscan apresentaram diminuição estatisticamente significativa do defocus, segunda ordem e aberrações totais. CONCLUSÕES: O retratamento personalizado foi superior ao retratamento convencional para a correção das aberrações oculares de baixa e alta ordens.PURPOSE: To compare the correction of ocular aberrations between custom and standard LASIK retreatment. METHODS: Prospective, randomized trial with paired eye control of 74 eyes from 37 patients who underwent LASIK retreatment. Each patient underwent retreatment using Zyoptix LASIK (Bausch & Lomb in 1 eye and Planoscan LASIK (Bausch & Lomb in the fellow eye. Correction of ocular aberrations was compared between custom and standard LASIK retreatments. RESULTS: At 6 months, there was a statistically significant reduction in defocus, astigmatism, coma, spherical aberration, second, third, higher-order and total aberration in Zyoptix eyes. There was a statistically significant reduction in defocus, second-order and total aberration in Planoscan eyes. CONCLUSIONS: Custom retreatment was statistically superior than standard retreatment for correction of lower

  4. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    Science.gov (United States)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  5. Modification of Deposited, Size-Selected MoS2 Nanoclusters by Sulphur Addition: An Aberration-Corrected STEM Study

    Directory of Open Access Journals (Sweden)

    Yubiao Niu

    2016-12-01

    Full Text Available Molybdenum disulphide (MoS2 is an earth-abundant material which has several industrial applications and is considered a candidate for platinum replacement in electrochemistry. Size-selected MoS2 nanoclusters were synthesised in the gas phase using a magnetron sputtering, gas condensation cluster beam source with a lateral time-of-flight mass selector. Most of the deposited MoS2 nanoclusters, analysed by an aberration-corrected scanning transmission electron microscope (STEM in high-angle annular dark field (HAADF mode, showed poorly ordered layer structures with an average diameter of 5.5 nm. By annealing and the addition of sulphur to the clusters (by sublimation in the cluster source, the clusters were transformed into larger, crystalline structures. Annealing alone did not lead to crystallization, only to a cluster size increase by decomposition and coalescence of the primary clusters. Sulphur addition alone led to a partially crystalline structure without a significant change in the size. Thus, both annealing and sulphur addition processes were needed to obtain highly crystalline MoS2 nanoclusters.

  6. Propagation of Aberrations through Phase Induced Amplitude Apodization coronagraph

    CERN Document Server

    Pueyo, Laurent; Shaklan, Stuart; 10.1364/JOSAA.28.000189

    2011-01-01

    The specification of polishing requirements for the optics in coronagraphs dedicated to exo-planet detection requires careful and accurate optical modelling. Numerical representations of the propagation of aberrations through the system as well as simulations of the broadband wavefront compensation system using multiple DMs are critical when one devises an error budget for such a class of instruments. In this communication we introduce an analytical tool that serves this purpose for Phase Induced Amplitude Apodisation (PIAA) coronagraphs. We first start by deriving the analytical form of the propagation of a harmonic ripple through a PIAA unit. Using this result we derive the chromaticity of the field at any plane in the optical train of a telescope equipped with such a coronagraph. Finally we study the chromatic response of a sequential DM wavefront actuator correcting such a corrugated field and thus quantify the requirements on the manufacturing of PIAA mirrors

  7. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  8. Effects of different contact lens correction on Zernike aberrations of human eye%不同角膜接触镜对人眼Zernike像差的影响

    Institute of Scientific and Technical Information of China (English)

    保金华; 贺极苍; 毛欣杰; 吕帆

    2013-01-01

    Background Even though the change in wavefront aberrations with correction modality is well documented in the literature,little is known about the underlying mechanism.Complete understanding of the causes responsible for the wavefront change in the combined lens-eye system is important since it provides basic knowledge for further improving the technique to correct refractive error by correcting lenses.Objective The aim of this study was to investigate the influence of refractive correction lens on optical property of the eye by analyzing Zernike aberrations in myopic eyes with contact lens correction.Methods This study was approved by the Ethic Committee of Wenzhou Medical College.Written informed consent was obtained from each subject before entering this study.Zernike aberrations of 52 myopic eyes of 26 subjects with the spherical equivalent-1.75 to-8.50 D were measured using a Hartmann-Shock wavefront sensor.The human eye aberrations were examined at the uncorrected condition,rigid-gas-permeable contact lens (RGP-CL) corrected condition and soft contact lens (Soft-CL) corrected condition.The differences of wavefront aberrations and Zernike coefficients were compared by repeated measurement of single factor variance analysis,and correlation of the aberration changes between uncorrected condition and RGP-CL corrected condition or Sofi-CL corrected condition,between the right eyes and left eyes in different conditions were analyzed by Pearson linear correlation.Results Mean total root-mean-square (tRMS) was (0.71 ± 0.30)μm,(0.54±0.19)μm and (0.74±0.32)μm in the uncorrected condition,RGP-CL corrected condition and Soft-CL corrected condition,with a significant difference (F =8.758,P<0.001),and tRMS was significant declined under the RGP-CL corrected condition compared with uncorrected condition (t =2.746,P =0.008),and tRMS in RGP-CL corrected condition was significantly lower than that in Soft-CL corrected condition (t =3.428,P =0.001).The high RMS (h

  9. Aberraciones cromáticas en aves de la colección ornitológica del Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” Chromatic aberrations in birds of the ornithological collection of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”

    Directory of Open Access Journals (Sweden)

    Matías Ricardo Urcola

    2011-12-01

    Full Text Available En el presente trabajo se determinan las aberraciones cromáticas que afectan el plumaje de las aves en la colección ornitológica del Museo Argentino de Ciencias Naturales de Buenos Aires. Estas alteraciones se deben a exceso o defecto en la producción y/o deposición del pigmento melanina, las familias afectadas pertenecen a Tinamidae, Spheniscidae, Ardeidae, Threskiornithidae, Anatidae, Falconidae, Rallidae, Charadriidae, Columbidae, Strigidae, Momotidae, Furnariidae, Mimidae, Motacillidae, Emberizidae e Icteridae. Dentro de las aberraciones propuestas el leucismo parcial (40,5 % es la más numerosa, seguida por la dilución pastel (23,8 %, albinismo (14,3 % y finalmente los plumajes brown, ino y eumelanismo parcial (7,1 % cada una.The paper makes out a strong case for determine chromatic aberrations that affect the coloring of the birds in the ornithological collection of the Museo Argentino de Ciencias Naturales de Buenos Aires. These alterations are due to excess or deficiency in the production and/or deposition of melanin pigment, the affect families belong to Tinamidae, Spheniscidae, Ardeidae, Threskiornithidae, Anatidae, Falconidae, Rallidae, Charadriidae, Columbidae, Strigidae, Momotidae, Furnariidae, Mimidae, Motacillidae, Emberizidae and Icteridae. Within the proposed changes, the partial leucism (40,5 % is the most numerous, followed by pastel dilution (23,8 %, albinism (14,3 % and finally brown aberrations, ino and partial eumelanism, each one of then had (7,1 %.

  10. 中国散裂中子源快循环同步加速器中色品校正及六极磁铁非线性效应%Chromatic correction for CSNS/RCS and nonlinear effects of chromaticity sextupoles

    Institute of Scientific and Technical Information of China (English)

    许守彦; 王生

    2013-01-01

    The rapid cycling synchrotron (RCS) of the China Spallation Neutron Source (CSNS) accumulates an 80 MeV injected beam,and accelerates 1.56 × 1013 particles to the design energy of 1.6 GeV,and extracts the high energy beam to the target.In order to keep low beam losses in the ring,it is necessary to control the chromaticity and to minimize the dependence of the optical properties on beam momentum spread.Three chromatic correction schemes are proposed and compared for CSNS/RCS in this paper.The combined effects of sextupole field and space charge are investigated by using the code SIMPSONS.The tune spread produced by chromaticity can be apparently reduced by using chromaticitysextupoles.However,the chromaticitysextupoles are non linear elements,and can introduce an amplitude dependent tuneshift.The combined effects ofsextupole field and space charge can induce some heam loss.%中国散裂中子源(CSNS)快循环同步加速器(RCS)把能量为80 MeV的束流储存并加速到1.6 GeV然后引出到靶站.为了减少RCS中的束流损失,有必要对RCS做色品校正,并减小动量偏移对束流光学的影响.尝试了多种色品校正方案并对不同色品校正方案做了比较.用三维跟踪程序SIMPSONS研究了色品校正六极铁与空间电荷效应对束流的影响.色品校正六极铁可以有效减小色品引起的频散,但是由于六极铁为非线性元件,导致不同振幅的粒子间有一定频散.模拟发现同时存在空间电荷效应和色品校正六极铁时,会有少量的束流损失.

  11. Correction of depth-induced spherical aberration for deep observation using two-photon excitation fluorescence microscopy with spatial light modulator.

    Science.gov (United States)

    Matsumoto, Naoya; Inoue, Takashi; Matsumoto, Akiyuki; Okazaki, Shigetoshi

    2015-07-01

    We demonstrate fluorescence imaging with high fluorescence intensity and depth resolution in which depth-induced spherical aberration (SA) caused by refractive-index mismatch between the medium and biological sample is corrected. To reduce the impact of SA, we incorporate a spatial light modulator into a two-photon excitation fluorescence microscope. Consequently, when fluorescent beads in epoxy resin were observed with this method of SA correction, the fluorescence signal of the observed images was ∼27 times higher and extension in the direction of the optical axes was ∼6.5 times shorter at a depth of ∼890 μm. Thus, the proposed method increases the depth observable at high resolution. Further, our results show that the method improved the fluorescence intensity of images of the fluorescent beads and the structure of a biological sample.

  12. Low chromate diet in dermatology

    Directory of Open Access Journals (Sweden)

    Sharma Ashimav

    2009-01-01

    Full Text Available Chromium is an essential trace element found in soil, water, air, and in the biosphere. It is the fourth most common element in the earth′s crust, mostly used to manufacture stainless steel and other alloys. Chromate allergy is not uncommon and its prevalence rate is reported to be 6%. Once developed, it tends to persist for a long time. Chromate is present in most of the dietary items. Chromate content in food often varies considerably from place to place. However, certain foods are routinely high in chromate content. Chromate in the diet of a chromate-sensitive person can provoke dermatitis. Careful selection of food with relatively low chromate concentration can bring a reduction in the total dietary intake of chromate per day. This can influence outcome of the disease, especially chronic vesicular hand eczema due to chromate sensitivity, and can benefit a chromate-sensitive patient.

  13. Aberration-corrected transmission electron microscopy analyses of GaAs/Si interfaces in wafer-bonded multi-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Häussler, Dietrich [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany); Houben, Lothar [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich GmbH, 52425 Juelich (Germany); Essig, Stephanie [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg (Germany); Kurttepeli, Mert [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany); Dimroth, Frank [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg (Germany); Dunin-Borkowski, Rafal E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich GmbH, 52425 Juelich (Germany); Jäger, Wolfgang, E-mail: wolfgang.jaeger@tf.uni-kiel.de [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany)

    2013-11-15

    Aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) investigations have been applied to investigate the structure and composition fluctuations near interfaces in wafer-bonded multi-junction solar cells. Multi-junction solar cells are of particular interest since efficiencies well above 40% have been obtained for concentrator solar cells which are based on III-V compound semiconductors. In this methodologically oriented investigation, we explore the potential of combining aberration-corrected high-angle annular dark-field STEM imaging (HAADF-STEM) with spectroscopic techniques, such as EELS and energy-dispersive X-ray spectroscopy (EDXS), and with high-resolution transmission electron microscopy (HR-TEM), in order to analyze the effects of fast atom beam (FAB) and ion beam bombardment (IB) activation treatments on the structure and composition of bonding interfaces of wafer-bonded solar cells on Si substrates. Investigations using STEM/EELS are able to measure quantitatively and with high precision the widths and the fluctuations in element distributions within amorphous interface layers of nanometer extensions, including those of light elements. Such measurements allow the control of the activation treatments and thus support assessing electrical conductivity phenomena connected with impurity and dopant distributions near interfaces for optimized performance of the solar cells. - Highlights: • Aberration-corrected TEM and EELS reveal structural and elemental profiles across GaAs/Si bond interfaces in wafer-bonded GaInP/GaAs/Si - multi-junction solar cells. • Fluctuations in elemental concentration in nanometer-thick amorphous interface layers, including the disrubutions of light elements, are measured using EELS. • The projected widths of the interface layers are determined on the atomic scale from STEM-HAADF measurements. • The effects of atom and ion beam activation treatment on the bonding

  14. Study on rubbing/chromatic-aberration test method in determining rub resistance in tipping paper’s printing layer%烟用接装纸印刷层耐摩擦性能的摩擦-色差测定法研究

    Institute of Scientific and Technical Information of China (English)

    沈世豪; 傅靖刚; 谢焰

    2014-01-01

    Cigarette paper may be polluted due to printing surface color separation of tipping paper resulting from poor rub resistance. Therefore, rub resistance of printing layer is seen as an important physical quality character of tipping paper. No special method had been used to test resistance performance until recently. Rubbing/chromatic-aberration test method was invented to test rub resistance for printing layer of tipping paper, which was discussed in such aspects as rub mechanism, qualitative analysis and quantitative analysis, and maneuverability. Rubbing/chromatic-aberration test method was found viable because of three advantages in above aspects:its rub mechanism was similar to that of real rub process in cigarette packing machine;both qualitative analysis and quantitative analysis were accurate and reliable;the experimental manipulation was convenient and timesaving. It was suitable for forming correlative standard to test and judge rub resistance in tipping paper's printing layer.%耐摩擦性是烟用接装纸印刷层的一项重要物理性能,接装纸外表面印刷层的耐摩擦性能差将导致印刷面的色层脱落引起卷烟拖色缺陷,并影响卷烟的外观质量,因而针对该项指标的检测成为国内外研究热点。本文对接装纸印刷层的耐摩性检测方法进行考察,研究开发了摩擦-色差测定法,并从方法的前处理、定性定量分析结果以及与机台实际运行过程的相似性三方面进行分析。研究显示:摩擦-色差测定法的摩擦机理与机台实际生产过程中的运行摩擦相似,其定性和定量分析结果准确可靠,前处理方法高效快捷,可作为系统的检测方法对接装纸印刷层的耐摩擦性能进行检测和判定。

  15. An aberration-corrected STEM study of structural defects in epitaxial GaN thin films grown by ion beam assisted MBE.

    Science.gov (United States)

    Poppitz, David; Lotnyk, Andriy; Gerlach, Jürgen W; Lenzner, Jörg; Grundmann, Marius; Rauschenbach, Bernd

    2015-06-01

    Ion-beam assisted molecular-beam epitaxy was used for direct growth of epitaxial GaN thin films on super-polished 6H-SiC(0001) substrates. The GaN films with different film thicknesses were studied using reflection high energy electron diffraction, X-ray diffraction, cathodoluminescence and primarily aberration-corrected scanning transmission electron microscopy techniques. Special attention was devoted to the microstructural characterization of GaN thin films and the GaN-SiC interface on the atomic scale. The results show a variety of defect types in the GaN thin films and at the GaN-SiC interface. A high crystalline quality of the produced hexagonal GaN thin films was demonstrated. The gained results are discussed.

  16. Local symmetry breaking of a thin crystal structure of β-Si3N4 as revealed by spherical aberration corrected high-resolution transmission electron microscopy images.

    Science.gov (United States)

    Kim, Hwang Su; Zhang, Zaoli; Kaiser, Ute

    2012-06-01

    This report is an extension of the study for structural imaging of 5-6 nm thick β-Si(3)N(4) [0001] crystal with a spherical aberration corrected transmission electron microscope by Zhang and Kaiser [2009. Structure imaging of β-Si(3)N(4) by spherical aberration-corrected high-resolution transmission electron microscopy. Ultramicroscopy 109, 1114-1120]. In this work, a local symmetry breaking with an uneven resolution of dumbbells in the six-membered rings revealed in the reported images in the study of Zhang and Kaiser has been analyzed in detail. It is found that this local asymmetry in the image basically is not relevant to a slight mistilt of the specimen and/or a beam tilt (coma). Rather the certain variation of the tetrahedral bond length of Si-N(4) in the crystal structure is found to be responsible for the uneven resolution with a local structural variation from region to region. This characteristic of the variation is also supposed to give a distorted lattice of apparently 2°-2.5° deviations from the perfect hexagonal unit cell as observed in the reported image in the work of Zhang and Kaiser. It is discussed that this variation may prevail only in a thin specimen with a thickness ranging ~≤ 5-6 nm. At the same time, it is noted that the average of the bond length variation is close to the fixed length known in a bulk crystal of β-Si(3)N(4).

  17. Variable aberration correction technology based on axially shifting cylinder-Zernike correcting element%基于轴向移动柱面-泽尼克校正元件的动态像差校正技术

    Institute of Scientific and Technical Information of China (English)

    曲贺盟; 张新; 王灵杰

    2012-01-01

    The most significant feature of elliptical window optical system is dynamic aberration change which is dependent on the scanning field. Thus, astigmatism and coma become the main factors which influence imaging quality of the optical system and the effect of astigmatism is most prominent. In this paper, a new method for dynamic aberration correction was presented in order to solve this problem. And this so-called cylinder-Zernike element correcting method combines the characteristics of cylindrical lens and Zernike plate. The outer surfaces of cylinder-Zernike correcting element were a pair of cylindrical surfaces whose generating lines were mutual perpendicular and the corresponding internal surfaces were Zernike fringe sag surfaces. This method could adjust the distance between the two cylinder-Zernike correcting elements in real time according to the change of scanning field to realize the correcting of dynamic aberration induced by elliptical window. It breaks through the bottleneck that the fixed correcting elements cannot achieve super wide scanning field. The imaging optical system in the giving example achieves ±55° scanning field. The Zernike aberration coefficients of astigmatism and coma in each scanning field are corrected into ±0.8 wavelength and the imaging quality of the elliptical window optical system is greatly improved.%椭球形窗口光学系统最显著的特点在于其依赖扫描视场的动态像差变化特性,像散和彗差成为影响光学系统成像质量的主要因素,其中像散的影响最为突出.为解决这一难题,结合柱面透镜和泽尼克位相板的特点,提出了一种新颖的动态像差校正方法,即柱面-泽尼克元件校正方法,此元件的外表面为一对母线互相垂直的圆柱面,对应的两个内表面为泽尼克边缘矢高表面.该方法随扫描视场的变化实时地调整一对柱面-泽尼克校正元件间距以实现椭球形窗口引入像差的动态校正.突破了固定校

  18. Chromatic functors of graphs

    OpenAIRE

    Yoshinaga, Masahiko

    2015-01-01

    Finite graphs that have a common chromatic polynomial have the same number of regular $n$-colorings. A natural question is whether there exists a natural bijection between regular $n$-colorings. We address this question using a functorial formulation. Let $G$ be a simple graph. Then for each set $X$ we can associate a set of $X$-colorings. This defines a functor, "chromatic functor" from the category of sets with injections to itself. The first main result verifies that two finite graphs dete...

  19. Cleaning of Chromate Manufacture Process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sodium chromate solubility is determined in the range of NaOH concentrations from 450 to 810 g/L and solution temperatures from 30 to 110 ℃. The optimized conditions to separate sodium chromate from NaOH in leached solution are resolved. It is first found the method to efficiently separate sodium chromate from NaOH and sodium aluminate in crude sodium chromate. Bench-scale studies on the separating are performed. Finally, good separation results are achieved.

  20. Chromatic polynomials for simplicial complexes

    DEFF Research Database (Denmark)

    Møller, Jesper Michael; Nord, Gesche

    2016-01-01

    In this note we consider s s -chromatic polynomials for finite simplicial complexes. When s=1 s=1 , the 1 1 -chromatic polynomial is just the usual graph chromatic polynomial of the 1 1 -skeleton. In general, the s s -chromatic polynomial depends on the s s -skeleton and its value at r r is the n...

  1. Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM.

    Science.gov (United States)

    Mahalingam, Krishnamurthy; Haugan, Heather J; Brown, Gail J; Eyink, Kurt G

    2013-04-01

    The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga-As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction.

  2. Investigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots emitting at 1.5μm using aberration-corrected scanning transmission electron microscopy

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Semenova, Elizaveta; Yvind, Kresten;

    2011-01-01

    The emission wavelength of InAs quantum dots grown on InP has been shown to shift to the technologically desirable 1.5μm with the deposition of 1–2 monolayers of GaAs on top of the quantum dots. Here, we use aberration-corrected scanning transmission electron microscopy to investigate morphologic...

  3. Correction

    DEFF Research Database (Denmark)

    Pinkevych, Mykola; Cromer, Deborah; Tolstrup, Martin

    2016-01-01

    [This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.].......[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.]....

  4. Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001 interface by aberration-corrected high-resolution transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    C. Wen

    2014-11-01

    Full Text Available The stacking faults (SFs in an AlSb/GaAs (001 interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM. The structure and strain distribution of the single and intersecting (V-shaped SFs associated with partial dislocations (PDs were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps εxx and εyy, a SF can be divided into several sections under different strain states (positive or negative strain values. Furthermore, the strain state for the same section of a SF is in contrast to each other in εxx and εyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed.

  5. On the benefit of aberration-corrected HAADF-STEM for strain determination and its application to tailoring ferroelectric domain patterns.

    Science.gov (United States)

    Tang, Y L; Zhu, Y L; Ma, X L

    2016-01-01

    Revealing strains on the unit-cell level is essential for understanding the particular performance of materials. Large-scale strain variations with a unit-cell resolution are important for studying ferroelectric materials since the spontaneous polarizations of such materials are strongly coupled with strains. Aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy (AC-HAADF-STEM) is not so sensitive to the sample thickness and therefore thickness gradients. Consequently it is extremely useful for large-scale strain determination, which can be readily extracted by geometrical phase analysis (GPA). Such a combination has various advantages: it is straightforward, accurate on the unit-cell scale, relatively insensitive to crystal orientation and therefore helpful for large-scale. We take a tetragonal ferroelectric PbTiO3 film as an example in which large-scale strains are determined. Furthermore, based on the specific relationship between lattice rotation and spontaneous polarization (Ps) at 180° domain-walls, the Ps directions are identified, which makes the investigation of ferroelectric domain structures accurate and straightforward. This method is proposed to be suitable for investigating strain-related phenomena in other ferroelectric materials.

  6. Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM

    Energy Technology Data Exchange (ETDEWEB)

    Mahalingam, Krishnamurthy, E-mail: Krishnamurthy.Mahalingam.ctr@wpafb.af.mil [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7707 (United States); Haugan, Heather J.; Brown, Gail J.; Eyink, Kurt G. [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7707 (United States)

    2013-04-15

    The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga–As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction. - Highlights: ►The strain distribution across interfaces in InAs–GaSb superlattices is examined. ► The GaSb-on-InAs interfaces are tensile, accounting for 27% of the overall strain. ► The InAs-on-GaSb interfaces are strain neutral. ► The GaSb layers are in compressive strain due to indium incorporation of about 4%. ► The strain in InAs layers is tensile, and is close to the bulk value of about 1%.

  7. Chromatic and Dispersive Effects in Nonlinear Integrable Optics

    CERN Document Server

    Webb, Stephen D; Valishev, Alexander; Nagaitsev, Sergei N; Danilov, Viatcheslav V

    2015-01-01

    Proton accumulator rings and other circular hadron accelerators are susceptible to intensity-driven parametric instabilities because the zero-current charged particle dynamics are characterized by a single tune. Landau damping can suppress these instabilities, which requires energy spread in the beam or introducing nonlinear magnets such as octupoles. However, this approach reduces dynamic aperture. Nonlinear integrable optics can suppress parametric instabilities independent of energy spread in the distribution, while preserving the dynamic aperture. This novel approach promises to reduce particle losses and enable order-of-magnitude increases in beam intensity. In this paper we present results, obtained using the Lie operator formalism, on how chromaticity and dispersion affect particle orbits in integrable optics. We conclude that chromaticity in general breaks the integrability, unless the vertical and horizontal chromaticities are equal. Because of this, the chromaticity correcting magnets can be weaker ...

  8. Holographically Correcting Synthetic Aperture Aberrations.

    Science.gov (United States)

    1987-12-01

    Malacara (20:105-148). The synthetic aperture was aligned in accordance with the synthetic-aperture alignment technique of Gill (8:61-64). The...1987. 20. Malacara , Daniel, ed. Optical Shop Testing. New York: John Wiley & Sons, 1978. 21. Marciniak, Capt Michael. Tutorial Presentation of mV

  9. Pupillary responses to chromatic stimulus

    Science.gov (United States)

    Suaste-Gomez, Ernesto; Rodriguez Guzman, M. C. Ma. Dolores A.; Druzgalski, Christopher

    2000-06-01

    Pupillary responses of the subjects under chromatic visual stimulation were filmed with video-oculography systems (VOG). Specifically, programmable chromatic visual stimuli were displayed on the monitor of a personal computer (PC) and responses tested in several normal subjects and those with ophthalmic pathologic conditions. Visual excitation utilized a reversal stimulus checkerboard pattern. Image processing techniques were applied in order to evaluate the pupil variations due to chromatic stimulation. In particular, the studies determined a relationship between pupillary response (PR) and steady-state retinal sensitivity (photopic vision). Finally, the retinal illuminance in trolands (td), as a product of the pupil area in mm2 and luminance in cd/m2 to full-field chromatic stimulation (FFCS) and checkerboard pattern reversal chromatic stimulation (CPRCS) was determined.

  10. 泽尼克多项式校正全息阵列光镊像差的实验研究%Aberrations in holographic array optical tweezers corrected with Zernike polynomials

    Institute of Scientific and Technical Information of China (English)

    刘伟伟; 任煜轩; 高红芳; 孙晴; 王自强; 李银妹

    2012-01-01

    像差会影响光镊对粒子的捕获效果.全息阵列光镊中,像差不仅来自光学元件,由特定算法设计的光阱相位片也会在光路中引入像差.本文通过液晶空间光调制器加载泽尼克多项式相位图,对全息阵列光镊中由光栅透镜组型算法引起的像差进行校正.结果显示:利用三阶泽尼克多项式可有效消除光路中由光栅透镜组型算法引起的慧差,使得捕获2“m聚苯乙烯小球的阵列光阱刚度提高了约40%;对比不同项的像差校正结果发现,全息阵列光镊中由算法引起的慧差与光学元件引起的像差一样,也会对阵列光阱的捕获效果产生较大影响;同时根据一阶像差校正结果可得光栅透镜组型算法对于一阶泽尼克像差具有鲁棒性.实验结果表明,对全息阵列光镊中由算法引起的像差进行校正,对于提高光阱的捕获效果和深化对算法特性的认识都具有重要意义.%Aberrations will degrade trapping performance of optical tweezers. In the holographic optical tweezers, aberrations originate not only from optical elements but also from holographic phase hologram of optical traps designed by a certain algorithna. We utilize a spatial light modulator to imprint Zernike polynomials phase hologram for correcting some certain aberrations in holographic array optical tweezers which are caused by grating and lens algorithm. The results show that thirdorder Zernike term can effectively correct coma due to the algorithm in the optical train, and the trap stiffness for 2 tm microns diameter polystyrene beads can reach 40%. Further comparison between different Zernike term aberration correction effects demonstrates that coma caused by grating and lens algorithm in the holographic array optical tweezer has the same serious influence on tweezer trapping performance as the aberrations originating from optical elements. Meanwhile, based on firstorder Zernike term

  11. Correction

    CERN Document Server

    2002-01-01

    Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.

  12. The influence of C{sub s}/C{sub c} correction in analytical imaging and spectroscopy in scanning and transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, Nestor J., E-mail: zaluzec@microscopy.com

    2015-04-15

    Aberration correction in scanning/transmission electron microscopy (S/TEM) owes much to the efforts of a small dedicated group of innovators. Leading that frontier has been Prof. Harald Rose. To date his leadership and dynamic personality has spearheaded our ability to leave behind many of the limitations imposed by spherical aberration (C{sub s}) in high resolution phase contrast imaging. Following shortly behind, has been the development of chromatic aberration correction (C{sub c}) which augments those accomplishments. In this paper we will review and summarize how the combination of C{sub s}/C{sub c} technology enhances our ability to conduct hyperspectral imaging and spectroscopy in today's and future computationally mediated experiments in both thin as well as realistic specimens in vacuo and during in-situ/environmental experiments.

  13. Optical Aberrations and Wavefront

    Directory of Open Access Journals (Sweden)

    Nihat Polat

    2014-08-01

    Full Text Available The deviation of light to create normal retinal image in the optical system is called aberration. Aberrations are divided two subgroup: low-order aberrations (defocus: spherical and cylindrical refractive errors and high-order aberrations (coma, spherical, trefoil, tetrafoil, quadrifoil, pentafoil, secondary astigmatism. Aberrations increase with aging. Spherical aberrations are compensated by positive corneal and negative lenticular spherical aberrations in youth. Total aberrations are elevated by positive corneal and positive lenticular spherical aberrations in elderly. In this study, we aimed to analyze the basic terms regarding optic aberrations which have gained significance recently. (Turk J Ophthalmol 2014; 44: 306-11

  14. Correction

    CERN Multimedia

    2002-01-01

    The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.   The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.

  15. Correction

    Directory of Open Access Journals (Sweden)

    2014-01-01

    Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].

  16. Correction.

    Science.gov (United States)

    2015-10-01

    In the article by Quintavalle et al (Quintavalle C, Anselmi CV, De Micco F, Roscigno G, Visconti G, Golia B, Focaccio A, Ricciardelli B, Perna E, Papa L, Donnarumma E, Condorelli G, Briguori C. Neutrophil gelatinase–associated lipocalin and contrast-induced acute kidney injury. Circ Cardiovasc Interv. 2015;8:e002673. DOI: 10.1161/CIRCINTERVENTIONS.115.002673.), which published online September 2, 2015, and appears in the September 2015 issue of the journal, a correction was needed. On page 1, the institutional affiliation for Elvira Donnarumma, PhD, “SDN Foundation,” has been changed to read, “IRCCS SDN, Naples, Italy.” The institutional affiliation for Laura Papa, PhD, “Institute for Endocrinology and Experimental Oncology, National Research Council, Naples, Italy,” has been changed to read, “Institute of Genetics and Biomedical Research, Milan Unit, Milan, Italy” and “Humanitas Research Hospital, Rozzano, Italy.” The authors regret this error.

  17. Commissioning of the nonlinear chromaticity at injection for LHC Run II

    CERN Document Server

    AUTHOR|(CDS)2080608; Tomas Garcia, Rogelio; Carlier, Felix Simon; Langner, Andy Sven; Malina, Lukas; Persson, Tobias Hakan Bjorn; Coello De Portugal - Martinez Vazquez, Jaime Maria; Skowronski, Piotr Krzysztof; Garcia-Tabares Valdivieso, Ana; CERN. Geneva. ATS Department

    2016-01-01

    For the first time, correction of nonlinear chromaticity and amplitude detuning was included in the LHC commissioning for Run II. The corrections found during the nonlinear optics commissioning have been deployed operationally at injection in the LHC. This note summarizes the relevant measurements and corrections performed during the first commissioning of the LHC in Run II

  18. Chromatic roots and hamiltonian paths

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2000-01-01

    We present a new connection between colorings and hamiltonian paths: If the chromatic polynomial of a graph has a noninteger root less than or equal to t(n) = 2/3 + 1/3 (3)root (26 + 6 root (33)) + 1/3 (3)root (26 - 6 root (33)) = 1.29559.... then the graph has no hamiltonian path. This result...

  19. First experimental test of a new monochromated and aberration-corrected 200 kV field-emission scanning transmission electron microscope.

    Science.gov (United States)

    Walther, T; Quandt, E; Stegmann, H; Thesen, A; Benner, G

    2006-01-01

    The first 200 kV scanning transmission electron microscope (STEM) with an imaging energy filter, a monochromator and a corrector for the spherical aberration (Cs-corrector) of the illumination system has been built and tested. The STEM/TEM concept with Koehler illumination allows to switch easily between STEM mode for analytical and TEM mode for high-resolution or in situ studies. The Cs-corrector allows the use of large illumination angles for retaining a sufficiently high beam current despite the intensity loss in the monochromator. With the monochromator on and a 3 microm slit in the dispersion plane that gives 0.26 eV full-width at half-maximum (FWHM) energy resolution we have obtained so far an electron beam smaller than 0.20 nm in diameter (FWHM as measured by scanning the spot quickly over the CCD) which contains 7 pA current and, according to simulations, should be around 0.12 nm in true size. A high-angle annular dark field (ADF) image with isotropic resolution better than 0.28 nm has been recorded with the monochromator in the above configuration and the Cs-corrector on. The beam current is still somewhat low for electron energy-loss spectroscopy (EELS) but is expected to increase substantially by optimising the condenser set-up and using a somewhat larger condenser aperture.

  20. First experimental test of a new monochromated and aberration-corrected 200 kV field-emission scanning transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Walther, T. [Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, D-53175 Bonn (Germany)]. E-mail: walther@caesar.de; Quandt, E. [Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, D-53175 Bonn (Germany); Stegmann, H. [Carl Zeiss Nano Technology Systems GmbH, Carl-Zeiss-Str. 56, D-73447 Oberkochen (Germany); Thesen, A. [Carl Zeiss Nano Technology Systems GmbH, Carl-Zeiss-Str. 56, D-73447 Oberkochen (Germany); Benner, G. [Carl Zeiss Nano Technology Systems GmbH, Carl-Zeiss-Str. 56, D-73447 Oberkochen (Germany)

    2006-10-15

    The first 200 kV scanning transmission electron microscope (STEM) with an imaging energy filter, a monochromator and a corrector for the spherical aberration (C {sub s}-corrector) of the illumination system has been built and tested. The STEM/TEM concept with Koehler illumination allows to switch easily between STEM mode for analytical and TEM mode for high-resolution or in situ studies. The C{sub s}-corrector allows the use of large illumination angles for retaining a sufficiently high beam current despite the intensity loss in the monochromator. With the monochromator on and a 3 {mu}m slit in the dispersion plane that gives 0.26 eV full-width at half-maximum (FWHM) energy resolution we have obtained so far an electron beam smaller than 0.20 nm in diameter (FWHM as measured by scanning the spot quickly over the CCD) which contains 7 pA current and, according to simulations, should be around 0.12 nm in true size. A high-angle annular dark field (ADF) image with isotropic resolution better than 0.28 nm has been recorded with the monochromator in the above configuration and the C {sub s}-corrector on. The beam current is still somewhat low for electron energy-loss spectroscopy (EELS) but is expected to increase substantially by optimising the condenser set-up and using a somewhat larger condenser aperture.

  1. Isochronicity Correction in the CR Storage Ring

    CERN Document Server

    Litvinov, S; Weick, H; Dolinskii, A

    2013-01-01

    A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR tuned in the isochronous ion-optical mode offers unique possibilities for measuring short-lived and very exotic nuclides. However, in a ring designed for maximal acceptance, many factors limit the resolution. One point is a limit in time resolution inversely proportional to the transverse emittance. But most of the time aberrations can be corrected and others become small for large number of turns. We show the relations of the time correction to the corresponding transverse focusing and that the main correction for large emittance corresponds directly to the chromaticity correction for transverse focusing of the beam. With the help of Monte-Carlo simulations for the full acceptance we demonstrate how to correct the revolution times so that in principle resolutions of dm/m=1E-6 ...

  2. Bacterial chromate reduction and product characterization

    Energy Technology Data Exchange (ETDEWEB)

    Mehlhorn, R.J. [Lawrence Berkeley Lab., CA (United States); Buchanan, B.B.; Leighton, T. [California Univ., Berkeley, CA (United States)

    1992-11-01

    Bacillus subtilis reduced hexavalent chromate to trivalent chromium under either aerobic or anaerobic conditions. Reduction of CR(VI) and appearance of extracellular Cr(III) were demonstrated by electron spin resonance and spectrophotometry. Chromate reduction was stimulated more than five-fold by freeze-thawing, indicating that intracellular reductases or chemical reductants reduce chromate more rapidly than do intact cells. Moderately concentrated cells (10% pellet volume after centrifugation) reduced approximately 40 {mu}M chromate/min (2 mg Cr/1-min) when exposed to 100 {mu}M chromate (5 mg Cr/1). Highly concentrated cells (70% pellet volume) reduced more than 99.8% of 2 mM chromate (100 mg Cr/1) within 15 min. This rate of chromate reduction was of the same order of magnitude as the rate of respiration in aerobic cells. A substantial fraction of the reduction product (ca. 75%) was extracellular Cr(M), which could readily be separated from the cells by centrifugation. At high chromate concentrations, some fraction of reduced CR(VI) appeared to be taken up by cells, consistent with a detection of intracellular paramagnetic products. At low chromate concentrations, undefined growth medium alone reduced Cr(VI), but at a slow rate, relative to cells. Under appropriate conditions, B. subtilis appears to be an organism of choice for detoxifying chromate-contaminated soil and water.

  3. Intraocular Lens Multifocality Combined with the Compensation for Corneal Spherical Aberration:A New Concept ofPresbyopia-CorrectingIntraocular Lens

    Directory of Open Access Journals (Sweden)

    Reiner Friedrich

    2012-10-01

    Full Text Available The outcomes of a prospective consecutive study aimed at evaluating the visual and refractive benefit after cataract surgery with the implantation of the aspheric diffractive multifocal intraocular lens (IOL Tecnis ZMB00 (Abbott Medical Optics are reported. A total of 31 eyes of 19 patients (age range, 40 to 81 years underwent phacoemulsification surgery with implantation of this aspheric multifocal IOL. At 6 months after surgery, postoperative spherical equivalent was within ±1.00 D in 96.8% of eyes, with 94.7% of patients presenting a postoperative binocular far LogMAR uncorrected visual acuity (UCVA of 0.1 or better. Far best-corrected distance VA improved significantly (p < 0.01, with postoperative values of 0.1 or better in 96.8% of eyes. Postoperative near UCVA was 0.10 (equivalent to J1 or better in 93.55% of eyes. Furthermore, the IOL power was found to be very poorly correlated with the postoperative far LogMAR (r = 0.13 and near UCVA (r = 0.13. In conclusion, the aspheric diffractive multifocal IOL Tecnis ZMB00 provides a restoration of the far and near visual function after phacoemulsification surgery for cataract removal or presbyopia correction, which is predictable and independent from the optical power of the implanted IOL.

  4. LHC IR upgrade dipole first with chromaticity and dynamic aperture issues

    CERN Document Server

    de Maria, R

    2007-01-01

    A dipole first layout for the LHC interaction region upgrade, while offering a potential reduction of the limitations due the long range beam-beam collisions, charged debris with respect to the quadrupole first layout, presents an enhancement of the chromatic and geometric aberration due large values in the triplet. These two effects are studied in the following for the dipole first option presented in [1].

  5. MEASURING CHROMATICITY ALONG THE RAMP USING THE PLL TUNE METER IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    TEPIKIAN,S.; AHRENS,L.; CAMERON,P.; SCHULTHEISS,C.

    2002-06-02

    Beam stability up the ramp requires the appropriate sign and magnitude of the chromaticity. We developed a way to measure the chromaticity using the PLL (Phase Locked Loop) tune-meter. Since, the accuracy of the PLL tune-meter with properly adjusted loop gain is better than {approx} 0.0001 in tune units, the radial loop needs only be changed by a small amount of 0.2mm at a 1Hz rate. Thus, we can achieve fast chromaticity measurements in 1 sec. Except during the very beginning of the ramp where there are snapback effects and the gamma changes very rapidly, we can have good chromaticcity measurements along the ramp. This leads to the possibility of correcting the chromaticity during the ramp using a feedback system.

  6. Changes of wavefront aberrations in keratoconus corrected with rigid gas permeable contact lens%圆锥角膜患者配戴硬性透氧性角膜接触镜后波前像差的改变

    Institute of Scientific and Technical Information of China (English)

    张立华; 王兵; 贾丁; 冯恬风; 董慧

    2012-01-01

    Objective To investigate the changes of wavefront aberrations in keratoconus corrected with rigid gas permeable contact lens (RGPCL).Methods It was a prospective case-control study.Twenty-five patients (43 eyes) confirmed by corneal topography as keratoconus were corrected with RGPCL.Their corrected visual acuity (VA) and wavefront aberrations were detected by iTrace dynamic laserefraction before and after wearing RGPCL for 2 weeks.Lower-order abberations LOAs,higher-order abberation HOAs,coma,spherical and trefoil were measured.The results measured were compared using paired samples t test.Results There were statistic differences in total ocular wavefront aberrations,LOAs,HOAs,coma and trefoil.Total ocular wavefront aberrations were reduced from 9.12±4.20 μm to 1.67±0.92 μm after wearing RGPCL (t=9.062,P<0.01); LOAs were reduced from 8.88-±3.90 μm to 1.37±0.75 μm after wearing RGPCL (t=9.507,P<0.01); HOAs were reduced from 1.90±0.14 μm to 0.79±0.21 μm after wearing RGPCL (t=2.473,P<0.05); coma were reduced from 0.99±0.15 μm to 0.30±0.18 μm after wearing RGPCL (t=2.364,P<0.05); trefoil were reduced from 0.92±0.19 μm to 0.22±0.14 μm after wearing RGPCL (t=2.757,P<0.05).There were no statistics differences in spherical abberation.Spherical abberation were reduced from 0.54±0.25 μm to 0.32±0.27 μm after wearing RGPCL (t=1.239,P>0.05).Conclusion Keratoconus patients with RGPCL can reach satisfying corrected visual acuity and visual quantity.Total ocular wavefront aberrations were significant reduced after wearing RGPCL.%目的 研究圆锥角膜患者配戴硬性透氧性角膜接触镜(RGPCL)后波前像差及视觉质量的改变.方法 前瞻性病例对照研究.收集在山西省眼科医院就诊的圆锥角膜患者25例(43眼),选配合适的RGPCL配戴2周后,分别于配戴前及配戴后测定其矫正视力,采用iTrace波前像差仪进行戴镜前后的全眼波前像差测量,并测量戴镜前后高阶、低阶像差

  7. Connections between the matching and chromatic polynomials

    Directory of Open Access Journals (Sweden)

    E. J. Farrell

    1992-01-01

    Full Text Available The main results established are (i a connection between the matching and chromatic polynomials and (ii a formula for the matching polynomial of a general complement of a subgraph of a graph. Some deductions on matching and chromatic equivalence and uniqueness are made.

  8. CIRCULAR CHROMATIC NUMBER AND MYCIELSKI GRAPHS

    Institute of Scientific and Technical Information of China (English)

    Liu Hongmei

    2006-01-01

    For a general graph G, M(G) denotes its Mycielski graph. This article gives a number of new sufficient conditions for G to have the circular chromatic number xc (M(G))equals to the chromatic number x(M(G)), which have improved some best sufficient conditions published up to date.

  9. Image-based EUVL aberration metrology

    Science.gov (United States)

    Fenger, Germain Louis

    A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberration. As resolution of nanolithography systems increases, effects of wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate in-situ aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials.

  10. Device with foil corrector for electron optical aberrations at low energy

    NARCIS (Netherlands)

    Kruit, P.; Van Aken, R.H.

    2004-01-01

    An electron optical device for, in use, creating negative spherical and chromatic aberration and reducing the energy spread in an electron beam travelling on an optical axis, including: at least one conducting plate substantially perpendicular to the optical axis with a first aperture having a first

  11. Impact of dimming white LEDs: chromaticity shifts due to different dimming methods

    Science.gov (United States)

    Dyble, Marc; Narendran, Nadarajah; Bierman, Andrew; Klein, Terence

    2005-09-01

    The goal of this study was to characterize the chromaticity shift that mixed-color and phosphor-converted white LED systems undergo when dimmed. As light-emitting diodes continue to rapidly evolve as a viable light source for lighting applications, their color shift while being dimmed should meet the current requirements of traditional lighting sources. Currently, LED system manufacturers commonly recommend pulse-width-modulation or PWM dimming schemes for operation of LED systems. PWM has the ability to achieve lower intensity levels and more linear control of light intensity compared to continuous current dimming methods. However, little data has been published on the effect dimming has on chromaticity shift of white LED lighting systems. The primary objective of this study was to quantify chromaticity shifts in mixed-color and phosphor-converted white LED systems due to continuous current dimming and pulse-width-modulation dimming schemes. In this study, the light output of the LED system was reduced from 100% to 3% by means of continuous current reduction or PWM methods using a PC white LED system and a mixed-color RGB LED system. Experimental results from this study showed that the PC white LED system exhibited very little chromaticity shift (less than a 4-step MacAdam ellipse) when the light level was changed from 100% to 3% using both dimming schemes. Compared to PC white LEDs, the mixed-color RGB LED system tested in this study showed very large chromaticity shifts in a similar dimming range using both dimming schemes. If a mixed-color RGB system is required, then some active feedback system control must be incorporated to obtain non-perceivable chromaticity shift. In this regard the chromaticity shift caused by the PWM method is easier to correct than the chromaticity shift caused by the continuous current dimming method.

  12. Tune and Chromaticity Control During Snapback and Ramp in 2015 LHC Operation

    CERN Document Server

    Schaumann, Michaela; Lamont, Mike; Solfaroli Camillocci, Matteo; Todesco, Ezio; Wenninger, Jorg

    2016-01-01

    Because of current redistribution on the superconducting cables, the harmonic components of the magnetic fields of the superconducting magnets in the Large Hadron Collider (LHC) show decay during the low field injection plateau. This results in tune and chromaticity variations for the beams. In the first few seconds of the ramp the original hysteresis state of the magnetic field is restored - the field snaps back. These fast dynamic field changes lead to strong tune and chromaticity excursions that, if not properly controlled, induce beam losses and potentially trigger a beam dump. A feed-forward system applies predicted corrections during the injection plateau and to the first part of the ramp to avoid violent changes of beam conditions. This paper discusses the snapback of tune and chromaticity as observed in 2015, as well as the control of beam parameters during the ramp. It also evaluates the quality of the applied feed-forward corrections and their reproducibility.

  13. Environmental TEM in an Aberration Corrected Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    ‐resolution imaging. A gaseous atmosphere in the pole‐piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 10‐20 nm), the gas in the environmental...... the microscope column. The effects of gas on the electron wave in the objective lens are not well understood and needs further attention. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast, provides a means for understanding...... results from imaging in various elemental as well as di‐molecular gases and their effect on imaging and spectroscopy in the environmental transmission electron microscope....

  14. Correcting Aberrated Wavefronts from Synthetic Apertures Holographically.

    Science.gov (United States)

    1986-12-01

    subject and reference legs was proven to be planar through both shear-plate interferometric analysis ( Malacara , pp 105-48) and by observing the...London: Cam- bridge University Press, 1969 Malacara . Daniel, ed. Optical Shop Testing. New York: John Wiley and Sons, 1978. Marathay, Arvind S

  15. Chromate conversion coatings and their current application

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-04-01

    Full Text Available This paper describes formation, composition and possible production technologies of application chromate coatings. Summation of common examples of applications of these coatings in corrosion protection of metals and alloys is provided. Individual chromate coatings are divided by their dominant anions either with CrVI or CrIII. Restrictions of chromate coatings with dominantly CrVI and related toxicity of hexavalent chromium is discussed in detail. In conclusion, examples of both chromium and other, alternative coatings are summed up. Application of these coatings as a protection for concrete hot-dip galvanized reinforcement is also reviewed.

  16. Aberration analysis based on pinhole-z-scan method near the focal point of refractive systems

    Science.gov (United States)

    Castro-Marín, Pablo; Garduño-Mejía, Jesús; Rosete-Aguilar, Martha; Bruce, Neil C.; Reid, Derryck T.; Farrell, C.; Sandoval-Romero, Gabriel E.

    2016-09-01

    In this work we present a method used to study the spherical and chromatic aberrations contribution near the focal point of a refractive optical system. The actual focal position is measured by scanning a pinhole attached on the front of a power detector, which are scanned along the optical axis using a motorized stage with 1 μm resolution. Spherical aberration contribution was analyzed by changing the pupil aperture, by modifying the size of the input iris diaphragm and for each case, measuring the actual laser power vs the detector position. Chromatic aberration was analyzed by performing the same procedure but in this case we used an ultra-broad-band femtosecond laser. The results between ML and CW operation were compare. Experimental results are presented.

  17. On topological relaxations of chromatic conjectures

    CERN Document Server

    Simonyi, Gábor

    2010-01-01

    There are several famous unsolved conjectures about the chromatic number that were relaxed and already proven to hold for the fractional chromatic number. We discuss similar relaxations for the topological lower bound(s) of the chromatic number. In particular, we prove that such a relaxed version is true for the Behzad-Vizing conjecture and also discuss the conjectures of Hedetniemi and of Hadwiger from this point of view. For the latter, a similar statement was already proven in an earlier paper of the first author with G. Tardos, our main concern here is that the so-called odd Hadwiger conjecture looks much more difficult in this respect. We prove that the statement of the odd Hadwiger conjecture holds for large enough Kneser graphs and Schrijver graphs of any fixed chromatic number.

  18. Chromatic effects in long periodic transport channels

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko V. N.; Hao, Y.; Jing, Y.

    2015-05-03

    Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels.

  19. Sensing Phase Aberrations behind Lyot Coronagraphs

    Science.gov (United States)

    Sivaramakrishnan, Anand; Soummer, Rémi; Pueyo, Laurent; Wallace, J. Kent; Shao, Michael

    2008-11-01

    Direct detection of young extrasolar planets orbiting nearby stars can be accomplished from the ground with extreme adaptive optics and coronagraphy in the near-infrared, as long as this combination can provide an image with a dynamic range of 107 after the data are processed. Slowly varying speckles due to residual phase aberrations that are not measured by the primary wave-front sensor are the primary obstacle to achieving such a dynamic range. In particular, non-common optical path aberrations occurring between the wave-front sensor and the coronagraphic occulting spot degrade performance the most. We analyze the passage of both low and high spatial frequency phase ripples, as well as low-order Zernike aberrations, through an apodized pupil Lyot coronagraph in order to demonstrate the way coronagraphic filtering affects various aberrations. We derive the coronagraphically induced cutoff frequency of the filtering and estimate coronagraphic contrast losses due to low-order Zernike aberrations: tilt, astigmatism, defocus, coma, and spherical aberration. Such slowly varying path errors can be measured behind a coronagraph and corrected by a slowly updated optical path delay precompensation or offset asserted on the wave front by the adaptive optics (AO) system. We suggest ways of measuring and correcting all but the lowest spatial frequency aberrations using Lyot plane wave-front data, in spite of the complex interaction between the coronagraph and those mid-spatial frequency aberrations that cause image plane speckles near the coronagraphic focal plane mask occulter's edge. This investigation provides guidance for next-generation coronagraphic instruments currently under construction.

  20. Reactivation of latently infected HIV-1 viral reservoirs and correction of aberrant alternative splicing in the LMNA gene via AMPK activation: Common mechanism of action linking HIV-1 latency and Hutchinson-Gilford progeria syndrome.

    Science.gov (United States)

    Finley, Jahahreeh

    2015-09-01

    AMPK, a master regulator of cellular metabolism which has been shown to activate PKC-theta (θ) and is essential for T cell activation, may modulate the splicing activities of SRp55 as well as enhance a p32-mediated inhibition of ASF/SF2-induced alternative splicing, potentially correcting aberrant alternative splicing in the LMNA gene and reactivating latent viral HIV-1 reservoirs. Moreover, similar epigenetic modifications and cell cycle regulators also characterize the analogous stages of premature senescence in progeroid cells and latency in HIV-1 infected T cells. AMPK-activating compounds including metformin and resveratrol may thus embody a novel treatment paradigm linking the pathophysiology of HGPS with that of HIV-1 latency.

  1. Toward a unified chromatic induction model.

    Science.gov (United States)

    Otazu, Xavier; Parraga, C Alejandro; Vanrell, Maria

    2010-10-01

    In a previous work (X. Otazu, M. Vanrell, & C. A. Párraga, 2008b), we showed how several brightness induction effects can be predicted using a simple multiresolution wavelet model (BIWaM). Here we present a new model for chromatic induction processes (termed Chromatic Induction Wavelet Model or CIWaM), which is also implemented on a multiresolution framework and based on similar assumptions related to the spatial frequency and the contrast surround energy of the stimulus. The CIWaM can be interpreted as a very simple extension of the BIWaM to the chromatic channels, which in our case are defined in the MacLeod-Boynton (lsY) color space. This new model allows us to unify both chromatic assimilation and chromatic contrast effects in a single mathematical formulation. The predictions of the CIWaM were tested by means of several color and brightness induction experiments, which showed an acceptable agreement between model predictions and psychophysical data.

  2. Simulação computacional de cirurgias foto-refrativas personalizadas e precisão relacionada à ordem das aberrações ópticas Computational simulation of customized photorefractive surgery and precision of correction related to different order aberrations

    Directory of Open Access Journals (Sweden)

    Luis Alberto Vieira de Carvalho

    2007-12-01

    Full Text Available O objetivo principal deste trabalho foi o desenvolvimento e a implementação de um algoritmo para simulação de cirurgias foto-refrativas. Sabe-se que os atuais " flying-spot" lasers para cirurgia refrativa disponíveis no mercado ainda contêm limitações na correção de algumas aberrações de ordem alta. No entanto, há muito pouca informação quantitativa sobre os erros envolvidos em função da complexidade das aberrações. Aplicando-se superfícies objetivo descritas por uma série de coeficientes de Zernike e o conceito matemático de convolução, várias ablações personalizadas foram simuladas para várias aberrações, desde baixa ordem (esfero-cilíndricas até aberrações de décima ordem (como coma, aberração esférica, entre outras. Os resultados mostram que o perfil de ablação de cada pulso do laser assim como seu diâmetro são fatores críticos quando o objetivo é corrigir aberrações de alta ordem. Além disso, outras conclusões foram possíveis, como por exemplo a de que nem todas as aberrações de alta ordem induzem aos mesmos erros na ablação. Também foi possível verificar que a correção de aberrações de alta ordem nos termos radiais (como aberração esférica é bem mais difícil do que naqueles termos contendo alta frequência angular (como trefoil.PURPOSE: To develop and implement an algorithm for simulation of photorefractive surgery. It is well known that many flying-spot lasers in the market have limitations in correcting higher order aberrations, but there is little quantitative information about errors related to aberration complexity. METHODS: By applying known surfaces described by Zernike polynomials of different orders it was possible to simulate several target surfaces that may well resemble in vivo cases of refractive surgery candidates. An algorithm that uses the mathematical concept of convolution was implemented and several simulated surfaces were tested, ranging from low order

  3. Alteration of introns in a hyaluronan synthase 1 (HAS1 minigene convert Pre-mRNA [corrected] splicing to the aberrant pattern in multiple myeloma (MM: MM patients harbor similar changes.

    Directory of Open Access Journals (Sweden)

    Jitra Kriangkum

    Full Text Available Aberrant pre-mRNA splice variants of hyaluronan synthase 1 (HAS1 have been identified in malignant cells from cancer patients. Bioinformatic analysis suggests that intronic sequence changes can underlie aberrant splicing. Deletions and mutations were introduced into HAS1 minigene constructs to identify regions that can influence aberrant intronic splicing, comparing the splicing pattern in transfectants with that in multiple myeloma (MM patients. Introduced genetic variations in introns 3 and 4 of HAS1 as shown here can promote aberrant splicing of the type detected in malignant cells from MM patients. HAS1Vd is a novel intronic splice variant first identified here. HAS1Vb, an intronic splice variant previously identified in patients, skips exon 4 and utilizes the same intron 4 alternative 3'splice site as HAS1Vd. For transfected constructs with unaltered introns 3 and 4, HAS1Vd transcripts are readily detectable, frequently to the exclusion of HAS1Vb. In contrast, in MM patients, HAS1Vb is more frequent than HAS1Vd. In the HAS1 minigene, combining deletion in intron 4 with mutations in intron 3 leads to a shift from HAS1Vd expression to HAS1Vb expression. The upregulation of aberrant splicing, exemplified here by the expression of HAS1Vb, is shown here to be influenced by multiple genetic changes in intronic sequences. For HAS1Vb, this includes enhanced exon 4 skipping and increased usage of alternative 3' splice sites. Thus, the combination of introduced mutations in HAS1 intron3 with introduced deletions in HAS1 intron 4 promoted a shift to an aberrant splicing pattern previously shown to be clinically significant. Most MM patients harbor genetic variations in intron 4, and as shown here, nearly half harbor recurrent mutations in HAS1 intron 3. Our work suggests that aberrant intronic HAS1 splicing in MM patients may rely on intronic HAS1 deletions and mutations that are frequent in MM patients but absent from healthy donors.

  4. Preliminary studies of a chromaticity tracker

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Cheng-Yang; /Fermilab

    2006-03-01

    A chromaticity tracker based on a method by D. McGinnis is proposed. This method starts with the slow modulation of the accelerating RF which causes the beam to respond to it. This beam modulation can be detected transversely with a Schottky pickup which after phase demodulation, the chromaticity can be calculated from it. However, to perform phase demodulation, the carrier frequency which is the betatron tune needs to be identified. The identification of the carrier frequency falls naturally onto the phase locked loop tune tracker which when locked to the betatron tune outputs this value in real time.

  5. Total dominator chromatic number of a graph

    Directory of Open Access Journals (Sweden)

    Adel P. Kazemi

    2015-06-01

    Full Text Available Given a graph $G$, the total dominator coloring problem seeks a proper coloring of $G$ with the additional property that every vertex in the graph is adjacent to all vertices of a color class. We seek to minimize the number of color classes. We initiate to study this problem on several classes of graphs, as well as finding general bounds and characterizations. We also compare the total dominator chromatic number of a graph with the chromatic number and the total domination number of it.

  6. A bivariate chromatic polynomial for signed graphs

    CERN Document Server

    Beck, Matthias

    2012-01-01

    We study Dohmen--P\\"onitz--Tittmann's bivariate chromatic polynomial $c_\\Gamma(k,l)$ which counts all $(k+l)$-colorings of a graph $\\Gamma$ such that adjacent vertices get different colors if they are $\\le k$. Our first contribution is an extension of $c_\\Gamma(k,l)$ to signed graphs, for which we obtain an inclusion--exclusion formula and several special evaluations giving rise, e.g., to polynomials that encode balanced subgraphs. Our second goal is to derive combinatorial reciprocity theorems for $c_\\Gamma(k,l)$ and its signed-graph analogues, reminiscent of Stanley's reciprocity theorem linking chromatic polynomials to acyclic orientations.

  7. Structure and Growth Mechanism of Lanthanum Chromate

    Institute of Scientific and Technical Information of China (English)

    Li Shengli; Liu Weiming; Ling Ziyu; Sun Liangcheng; Ao Qing; Fu Guifu

    2005-01-01

    The unit cell of lanthanum chromate was constructed by calculating equivalent points. By means of calculation of the hole octahedrally surrounded by O2- ions, it was considered that the sintered property of lanthanum chromate and the stability of Cr-O octahedron might be promoted by mixing a little Ca2+ ions. The growth mechanism was discussed in terms of structural ledge observed by SEM, the surfaces of the structural ledges parallel to (001), (010) and (110) planes, respectively. The misfit between (110) and (001) planes is only 0.0021 on common atomic plane, and the interconnection of the structured ledge may occur during crystal growth.

  8. The chromatic polynomial and list colorings

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2009-01-01

    We prove that, if a graph has a list of k available colors at every vertex, then the number of list-colorings is at least the chromatic polynomial evaluated at k when k is sufficiently large compared to the number of vertices of the graph.......We prove that, if a graph has a list of k available colors at every vertex, then the number of list-colorings is at least the chromatic polynomial evaluated at k when k is sufficiently large compared to the number of vertices of the graph....

  9. On the Star Chromatic Number of Graph Products

    Institute of Scientific and Technical Information of China (English)

    XU Chuan-liang; WANG Yi-ju

    2001-01-01

    The star chromatic number of a graph was introduced by A. Vince, which is a natural generalization of the chromatic number of a graph. In this paper, the star chromatic numbers of graph products G (×) H are discussed in some special cases.

  10. Chromatic Dispersion Estimation in Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Soriano, Ruben Andres; Hauske, Fabian N.; Guerrero Gonzalez, Neil;

    2011-01-01

    Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set the ac...

  11. Effects of aberrations in spatiotemporal focusing of ultrashort laser pulses.

    Science.gov (United States)

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2014-04-01

    Spatiotemporal focusing, or simultaneous spatial and temporal focusing (SSTF), has already been adopted for various applications in microscopy, photoactivation for biological studies, and laser fabrication. We investigate the effects of aberrations on focus formation in SSTF, in particular, the effects of phase aberrations related to low-order Zernike modes and a refractive index mismatch between the immersion medium and sample. By considering a line focus, we are able to draw direct comparison between the performance of SSTF and conventional spatial focusing (SF). Wide-field SSTF is also investigated and is found to be much more robust to aberrations than either line SSTF or SF. These results show the sensitivity of certain focusing methods to specific aberrations, and can inform on the necessity and benefit of aberration correction.

  12. The chromatic number of comparability 3-hypergraphs

    OpenAIRE

    2014-01-01

    Beginning with the concepts of orientation for a 3-hypergraph and transitivity for an oriented 3-hypergraph, it is natural to study the class of comparability 3-hypergraphs (those that can be transitively oriented). In this work we show three different behaviors in respect to the relationship between the chromatic number and the clique number of a comparability 3-hypergraph, this is in contrast with the fact that a comparability simple graph is a perfect graph.

  13. Schottky signal analysis: tune and chromaticity computation

    CERN Document Server

    Chanon, Ondine

    2016-01-01

    Schottky monitors are used to determine important beam parameters in a non-destructive way. The Schottky signal is due to the internal statistical fluctuations of the particles inside the beam. In this report, after explaining the different components of a Schottky signal, an algorithm to compute the betatron tune is presented, followed by some ideas to compute machine chromaticity. The tests have been performed with offline and/or online LHC data.

  14. Anisoplanatism in adaptive optics systems due to pupil aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B

    2005-08-01

    Adaptive optics systems typically include an optical relay that simultaneously images the science field to be corrected and also a set of pupil planes conjugate to the deformable mirror of the system. Often, in the optical spaces where DM's are placed, the pupils are aberrated, leading to a displacement and/or distortion of the pupil that varies according to field position--producing a type of anisoplanatism, i.e., a degradation of the AO correction with field angle. The pupil aberration phenomenon is described and expressed in terms of Seidel aberrations. An expression for anisoplanatism as a function of pupil distortion is derived, an example of an off-axis parabola is given, and a convenient method for controlling pupil-aberration-generated anisoplanatism is proposed.

  15. Multiplexed aberration measurement for deep tissue imaging in vivo

    OpenAIRE

    Wang, Chen; Liu, Rui; Milkie, Daniel E; Sun, Wenzhi; Tan, Zhongchao; Kerlin, Aaron; Chen, Tsai-Wen; Kim, Douglas S.; Ji, Na

    2014-01-01

    We describe a multiplexed aberration measurement method that modulates the intensity or phase of light rays at multiple pupil segments in parallel to determine their phase gradients. Applicable to fluorescent-protein-labeled structures of arbitrary complexity, it allows us to obtain diffraction-limited resolution in various samples in vivo. For the strongly scattering mouse brain, a single aberration correction improves structural and functional imaging of fine neuronal processes over a large...

  16. Multiplexed aberration measurement for deep tissue imaging in vivo

    Science.gov (United States)

    Wang, Chen; Liu, Rui; Milkie, Daniel E.; Sun, Wenzhi; Tan, Zhongchao; Kerlin, Aaron; Chen, Tsai-Wen; Kim, Douglas S.; Ji, Na

    2014-01-01

    We describe a multiplexed aberration measurement method that modulates the intensity or phase of light rays at multiple pupil segments in parallel to determine their phase gradients. Applicable to fluorescent-protein-labeled structures of arbitrary complexity, it allows us to obtain diffraction-limited resolution in various samples in vivo. For the strongly scattering mouse brain, a single aberration correction improves structural and functional imaging of fine neuronal processes over a large imaging volume. PMID:25128976

  17. Study of residual aberration for non-imaging focusing heliostat

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.T.; Chong, K.K.; Lim, B.H.; Lim, C.S. [Institute of Energy and Environment, Malaysia University of Science and Technology, No. 17, Jalan SS7/26, Kelana Jaya, 47301 Petaling Jaya, Selangor (Malaysia)

    2003-08-01

    Instead of using a specific focusing geometry, a non-imaging focusing heliostat has no fixed geometry but is composed of many small movable element mirrors that can be manoeuvred to eliminate the first-order aberration. Following our previous publication on the principle of non-imaging focusing heliostat, this paper further explores higher order residual aberration that limits the size of the focusing spot. The residual aberration can be partially corrected by offsetting the pivot point of mirrors and pre-setting the tilting angles of mirrors.

  18. Three-dimensional polarization aberration functions in optical system based on three-dimensional polarization ray-tracing calculus

    Science.gov (United States)

    He, Wenjun; Fu, Yuegang; Liu, Zhiying; Zhang, Lei; Wang, Jiake; Zheng, Yang; Li, Yahong

    2017-03-01

    The polarization aberrations of a complex optical system with multi-element lens have been investigated using a 3D polarization aberration function. The 3D polarization ray-tracing matrix has been combined with the optical path difference to obtain a 3D polarization aberration function, which avoids the need for a complicated phase unwrapping process. The polarization aberrations of a microscope objective have been analyzed to include, the distributions of 3D polarization aberration functions, diattenuation aberration, retardance aberration, and polarization-dependent intensity on the exit pupil. Further, the aberrations created by the field of view and the coating on the distribution rules of 3D polarization aberration functions are discussed in detail. Finally a novel appropriate field of view and wavelength correction is proposed for a polarization aberration function which optimizes the image quality of a multi-element optical system.

  19. Improved step-by-step chromaticity compensation method for chromatic sextupole optimization

    CERN Document Server

    Liu, Gang-Wen; Jia, Qi-Ka; Li, Wei-Min; Wang, Lin

    2015-01-01

    The step-by-step chromaticity compensation method for chromatic sextupole optimization and dynamic aperture increase was proposed by E. Levichev and P. Piminov (E. Levichev and P. Piminov, 2006 [1]). Although this method can be used to enlarge the dynamic aperture of storage ring, it has some drawbacks. In this paper, we combined this method with evolutionary computation algorithms, and proposed an improved version of this method. In the improved method, the drawbacks are avoided, and thus better optimization results can be obtained.

  20. Chromatic polynomials of graphs from Kac-Moody algebras

    OpenAIRE

    Venkatesh, R.; Viswanath, Sankaran

    2013-01-01

    We give a new interpretation of the chromatic polynomial of a simple graph G in terms of the Kac-Moody Lie algebra with Dynkin diagram G. We show that the chromatic polynomial is essentially the q-Kostant partition function of this Lie algebra evaluated on the sum of the simple roots. Applying the Peterson recurrence formula for root multiplicities, we obtain a new realization of the chromatic polynomial as a weighted sum of paths in the bond lattice of G.

  1. Photon Sieve Bandwidth Broadening by Reduction of Chromatic Aberration Effects Using Second-Stage Diffractive Optics

    Science.gov (United States)

    2015-03-26

    Large optical photon sieve,” Optics Letters , 30(22): 2976-2978 (November 2005). 2. Andersen, Geoff. Senior Researcher, Laser and Optics ...EFFECTS USING SECOND-STAGE DIFFRACTIVE OPTICS THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering...SECOND-STAGE DIFFRACTIVE OPTICS Christopher M. Tulip Major, USAF Committee Membership: Lt Col Anthony L. Franz, PhD Chair

  2. An Application of Chromatic Prototypes for a Universal Information System

    CERN Document Server

    McCool, Matthew

    2007-01-01

    This paper presents research on color prototypes, categories, and the neuropsychology of color. These data suggest that chromatic prototypes may be useful for thematically organizing information systems.

  3. Reexploring the upper bound for the chromatic number of graphs

    Institute of Scientific and Technical Information of China (English)

    LI Shuchao; MAO Jingzhong

    2004-01-01

    The upper bound of the chromatic number of simple graphs is explored. Its original idea comes from Coffman, Hakimi and Schmeichel, who recently studied the chromatic number of graphs with strong conditions. In this paper, corresponding conditions are weakened and the result proves that of Ershov and Kozhukhin's.

  4. On the chromatic number of general Kneser hypergraphs

    DEFF Research Database (Denmark)

    Alishahi, Meysam; Hajiabolhassan, Hossein

    2015-01-01

    In a break-through paper, Lovász [20] determined the chromatic number of Kneser graphs. This was improved by Schrijver [27], by introducing the Schrijver subgraphs of Kneser graphs and showing that their chromatic number is the same as that of Kneser graphs. Alon, Frankl, and Lovász [2] extended ...

  5. Linear and chromatic optics measurements at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Aiba, M.; Calaga, R.; Aiba, M.; Tomas, R.; Vanbavinkove, G.

    2010-05-23

    Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented. The primary goal of the RHIC experiments were execute an on-line measurement of the optics using the tools developed for the LHC. Turn-by-turn BPM trajectories (typically 1000 turns) acquired immediately after an external dipole kick are numerically analyzed to determine the optical parameters at the location of the beam position monitors (BPMs). For chromatic optics, a similar analysis, but on a beam with finite momentum offset(s). Each optical measurement typically is calculated from multiple data sets to capture statistical variations and ensure reproducibility. The procedure of measurement and analysis is detailed in ref [1, 2]. Two dedicated experiments were performed at RHIC with protons during Run 2009. The first at injection energy and optics and the other at 250 GeV and squeezed optics. The basic RHIC parameters relevant for the two experiments are listed in Table 1.

  6. On aberration in gravitational lensing

    CERN Document Server

    Sereno, M

    2008-01-01

    It is known that a relative translational motion between the deflector and the observer affects gravitational lensing. In this paper, a lens equation is obtained to describe such effects on actual lensing observables. Results can be easily interpreted in terms of aberration of light-rays. Both radial and transverse motions with relativistic velocities are considered. The lens equation is derived by first considering geodesic motion of photons in the rest-frame Schwarzschild spacetime of the lens, and, then, light-ray detection in the moving observer's frame. Due to the transverse motion images are displaced and distorted in the observer's celestial sphere, whereas the radial velocity along the line of sight causes an effective re-scaling of the lens mass. The Einstein ring is distorted to an ellipse whereas the caustics in the source plane are still point-like. Either for null transverse motion or up to linear order in velocities, the critical curve is still a circle with its radius corrected by a factor (1+z...

  7. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

    2000-06-01

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool.

  8. PMMA-based ophthalmic contact lens for vision correction of strabismus

    Science.gov (United States)

    Asgharzadeh Shishavan, Amir; Nordin, Leland; Tjossem, Paul; Abramoff, Michael D.; Toor, Fatima

    2016-09-01

    In this work we present the design of a novel ophthalmic prismatic contact lens to correct for strabismus. Strabismus, colloquially called "crossed-eyes" or "wall eyes," is a condition in which the eyes are not properly aligned with each other. To our knowledge there are no contact lenses that allow for strabismus correction. To address this, we have designed a poly methyl methacrylate (PMMA) based prismatic correction contact lens. Therefore, we modeled a Fresnel lens with the appropriate optical properties and a human eye in COMSOL Multiphysics Ray Optics module. Our first design was created by mapping Fresnel lenses onto the curved surface of the eye, the focus of light on retina was suboptimal. Next we determined two more potential solutions and improved the light focus on the retina but there were still some issues. A small fraction of light ( 5%) diverged and could not be focused. Due to dispersive characteristic of PMMA, chromatic aberration was present. We will use our ray optics solution and convert into a metasurface nanophotonic lens that has the identical behavior and mitigates the issues related with prismatic lens.

  9. Cosmological parameter estimation: impact of CMB aberration

    CERN Document Server

    Catena, Riccardo

    2012-01-01

    The peculiar motion of an observer with respect to the CMB rest frame induces an apparent deflection of the observed CMB photons, i.e. aberration, and a shift in their frequency, i.e. Doppler effect. Both effects distort the temperature multipoles a_lm's via a mixing matrix at any l. The common lore when performing a CMB based cosmological parameter estimation is to consider that Doppler affects only the l=1 multipole, and neglect any other corrections. In this paper we reconsider the validity of this assumption, showing that it is actually not robust when sky cuts are included to model CMB foreground contaminations. Assuming a simple fiducial cosmological model with five parameters, we simulated CMB temperature maps of the sky in a WMAP-like and in a Planck-like experiment and added aberration and Doppler effects to the maps. We then analyzed with a MCMC in a Bayesian framework the maps with and without aberration and Doppler effects in order to assess the ability of reconstructing the parameters of the fidu...

  10. Chromatic control in coextruded layered polymer microlenses

    CERN Document Server

    Crescimanno, Michael; Andrews, James H; Zhou, Chuanhong; Petrus, Joshua B; Merlo, Cory; Bagheri, Cameron; Hetzel, Connor; Tancabel, James; Singer, Kenneth D; Baer, Eric

    2015-01-01

    We describe the formation, characterization and theoretical understanding of microlenses comprised of alternating polystyrene and polymethylmethacrylate layers produced by multilayer coextrusion. These lenses are fabricated by photolithography, using a grayscale mask followed by plasma etching, so that the refractive index alternation of the bilayer stack appears across the radius of the microlens. The alternating quarter-wave thick layers form a one-dimensional photonic crystal whose dispersion augments the material dispersion, allowing one to sculpt the chromatic dispersion of the lens by adjusting the layered structure. Using Huygen's principle, we model our experimental measurements of the focal length of these lenses across the reflection band of the multilayer polymer film from which the microlens is fashioned. For a 56 micron diameter multilayered lens of focal length 300 microns, we measured a nearly 25 percent variation in the focal length across a shallow, 50 nm-wide reflection band.

  11. Molybdate based Alternatives to Chromating as a Passivation Treatment for Zinc

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Bech-Nielsen, G.; Møller, Per

    1994-01-01

    in chromating. The corrosion protection provided by the process on zinc-plated parts is comparable to chromates. Depending on test conditions, especially pH value, the molybdate/phosphate process was found to be better than chromate at low pH values, equal to chromates in outdoor exposure tests and prohesion...

  12. Using Aberrant Behaviors as Reinforcers for Autistic Children.

    Science.gov (United States)

    Charlop, Marjorie H.; And Others

    1990-01-01

    Three experiments assessed the efficacy of various reinforcers to increase correct task responding in a total of 10 autistic children, aged 6-9. Of the reinforcers used (stereotypy, delayed echolalia, perseverative behavior, and food), task performance was highest with opportunities to engage in aberrant behaviors, and lowest with edible…

  13. Chromatic Polynomials Of Some (m,l-Hyperwheels

    Directory of Open Access Journals (Sweden)

    Julian A. Allagan

    2014-03-01

    Full Text Available In this paper, using a standard method of computing the chromatic polynomial of hypergraphs, we introduce a new reduction theorem which allows us to find explicit formulae for the chromatic polynomials of some (complete non-uniform $(m,l-$hyperwheels and non-uniform $(m,l-$hyperfans. These hypergraphs, constructed through a ``join" graph operation, are some generalizations of the well-known wheel and fan graphs, respectively. Further, we revisit some results concerning these graphs and present their chromatic polynomials in a standard form that involves the Stirling numbers of the second kind.

  14. Abnormal pupillary light reflex with chromatic pupillometry in Gaucher disease

    Science.gov (United States)

    Narita, Aya; Shirai, Kentarou; Kubota, Norika; Takayama, Rumiko; Takahashi, Yukitoshi; Onuki, Takanori; Numakura, Chikahiko; Kato, Mitsuhiro; Hamada, Yusuke; Sakai, Norio; Ohno, Atsuko; Asami, Maya; Matsushita, Shoko; Hayashi, Anri; Kumada, Tomohiro; Fujii, Tatsuya; Horino, Asako; Inoue, Takeshi; Kuki, Ichiro; Asakawa, Ken; Ishikawa, Hitoshi; Ohno, Koyo; Nishimura, Yoko; Tamasaki, Akiko; Maegaki, Yoshihiro; Ohno, Kousaku

    2014-01-01

    The hallmark of neuronopathic Gaucher disease (GD) is oculomotor abnormalities, but ophthalmological assessment is difficult in uncooperative patients. Chromatic pupillometry is a quantitative method to assess the pupillary light reflex (PLR) with minimal patient cooperation. Thus, we investigated whether chromatic pupillometry could be useful for neurological evaluations in GD. In our neuronopathic GD patients, red light-induced PLR was markedly impaired, whereas blue light-induced PLR was relatively spared. In addition, patients with non-neuronopathic GD showed no abnormalities. These novel findings show that chromatic pupillometry is a convenient method to detect neurological signs and monitor the course of disease in neuronopathic GD. PMID:25356393

  15. CHROMATIC-AREA EFFECT ON HOMOGENEOUS COLOR OF A ROOM FLOOR IN NATURAL INDOOR ENVIRONMENT

    OpenAIRE

    2009-01-01

    Chromatic-area effect is a phenomenon by which color appearance of chromatic surface changes when a size (visual angle) of increases without any physical change of the surface. Lightness and saturation of a large chromatic area generally increase compared to a smaller chromatic area. We investigated this chromatic-area effect on homogeneous color of a room floor under light environment in the day (white daylight) and in the night (a fluorescent lamp). Observes performed color matching between...

  16. Spherical aberration from trajectories in real and hard-edge solenoid fields

    Indian Academy of Sciences (India)

    BISWAS B

    2016-06-01

    For analytical, real and hard-edge solenoidal axial magnetic fields, the low-energy electron trajectories are obtained using the third-order paraxial ray equation. Using the particle trajectories, it is shown that the spherical aberration in the hard-edge model is high and it increases monotonously with hard edginess, although the focal length converges, in agreement with a recentfield and spherical aberration model. The model paved the way for a hard-edge approximation that gives correct focal length and spherical aberration, which is verified here by the trajectory method. In essence, we show that exact hard-edge fields give infinite spherical aberrations.

  17. Chromatic Shadow Detection and Tracking for Moving Foreground Segmentation

    DEFF Research Database (Denmark)

    Huerta, Ivan; Holte, Michael Boelstoft; Moeslund, Thomas B.;

    2015-01-01

    chromatic moving cast shadow regions and those regions detected as moving objects. In essence, those regions corresponding to potential shadows are detected based on edge partitioning and colour statistics. Subsequently (i) temporal similarities between textures and (ii) spatial similarities between...

  18. Chromatic $k$-Mean Clustering in High Dimensional Space

    CERN Document Server

    Ding, Hu

    2012-01-01

    In this paper, we study a new type of clustering problem, called {\\em Chromatic Clustering}, in high dimensional space. Chromatic clustering seeks to partition a set of colored points into groups (or clusters) so that no group contains points with the same color and a certain objective function is optimized. In this paper, we focus on $k$-mean clustering, and investigate its hardness and approximation solutions. The additional coloring requirement destroys some key properties used in existing $k$-mean clustering techniques (for the ordinary clustering problem), and significantly complicates the problem. There is no FPTAS for the chromatic clustering problem, even if $k=2$. Based on several new geometric observations and an interesting sphere peeling approach, we show that a near linear time (on $n$ and $d$) $(1+\\epsilon)$-approximation is, however, still achievable for the chromatic clustering problem.

  19. Study of the wavefront aberrations in children with amblyopia

    Institute of Scientific and Technical Information of China (English)

    ZHAO Peng-fei; ZHOU Yue-hua; WANG Ning-li; ZHANG Jing

    2010-01-01

    Background Amblyopia is a common ophthalmological condition and the wavefront aberrometer is a relatively new diagnostic tool used globally to measure optical characteristics of human eyes as well as to study refractive errors in amblyopic eyes. We studied the wavefront aberration of the amblyopic children's eyes and analyzed the mechanism of the wavefront aberration in the formation of the amblyopia, try to investigate the new evidence of the treatment of the amblyopia, especially in the refractory amblyopia.Methods The WaveScan Wavefront System (VISX, USA) aberrometer was used to investigate four groups of children under dark accommodation and cilliary muscle paralysis. There were 45 cases in the metropic group, 87 in the amblyopic group, 92 in the corrected-amblyopic group and 38 in the refractory amblyopic group. One-way analysis of variance (ANOVA), t-test and multivariate linear regression were used to analyze all the data.Results Third order to 6th order aberrations showed a decreasing trend whereas in the higher order aberrations the main ones were 3rd order coma (Z3-1-Z31), trefoil (Z3-3-Z33) and 4th order aberration (Z40); and 3rd order coma represented the highest percentage of all three main aberrations. Within 3rd order coma, vertical coma (Z3-1) accounted for a greater percentage than horizontal coma (Z31). Significant differences of vertical coma were found among all clinical groups of children: vertical coma in the amblyopic group (0.17±0.15) was significantly higher than in the metropic group (0.11±0.13, P0.05).Conclusions Although lower order aberrations such as defocus (myopia and hyperopia) and astigmatism are major factors determining the quality of the retinal image, higher order aberrations also need to be considered in amblyopic eyes as their effects are significant.

  20. All-fiber interferometer for chromatic dispersion measurements

    OpenAIRE

    Thévenaz, Luc; Pellaux, J. P.; Von der Weid, J. P.

    1988-01-01

    An all-fiber interferometric method for chromatic dispersion measurements in meter-length single-mode fibers is presented. In a Michelson setup the physical length of a reference fiber was varied so as to obtain adjustable optical delay. Time resolution, ease of manipulation, and mechanical isolation are considerably improved with respect to conventional interferometers. Resolution of group delay measurement and chromatic dispersion over the full 1100-1700-nm spectral range are better than 5 ...

  1. Phase aberration effects in elastography.

    Science.gov (United States)

    Varghese, T; Bilgen, M; Ophir, J

    2001-06-01

    In sonography, phase aberration plays a role in the corruption of sonograms. Phase aberration does not have a significant impact on elastography, if statistically similar phase errors are present in both the pre- and postcompression signals. However, if the phase errors are present in only one of the pre- or postcompression signal pairs, the precision of the strain estimation process will be reduced. In some cases, increased phase errors may occur only in the postcompression signal due to changes in the tissue structure with the applied compression. Phase-aberration effects increase with applied strain and may be viewed as an image quality derating factor, much like frequency-dependent attenuation or undesired lateral tissue motion. In this paper, we present a theoretical and simulation study of the effects of phase aberration on the elastographic strain-estimation process, using the strain filter approach.

  2. Studies on biological reduction of chromate by Streptomyces griseus

    Energy Technology Data Exchange (ETDEWEB)

    Poopal, Ashwini C. [Division of Biochemical Sciences, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008 (India); Laxman, R. Seeta, E-mail: rseetalaxman@yahoo.co.in [Division of Biochemical Sciences, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008 (India)

    2009-09-30

    Chromium is a toxic heavy metal used in various industries and leads to environmental pollution due to improper handling. The most toxic form of chromium Cr(VI) can be converted to less toxic Cr(III) by reduction. Among the actinomycetes tested for chromate reduction, thirteen strains reduced Cr(VI) to Cr(III), of which one strain of Streptomyces griseus (NCIM 2020) was most efficient showing complete reduction within 24 h. The organism was able to use a number of carbon sources as electron donors. Sulphate, nitrate, chloride and carbonate had no effect on chromate reduction during growth while cations such as Cd, Ni, Co and Cu were inhibitory to varying degrees. Chromate reduction was associated with the bacterial cells and sonication was the best method of cell breakage to release the enzyme. The enzyme was constitutive and did not require presence of chromate during growth for expression of activity. Chromate reduction with cell free extract (CFE) was observed without added NADH. However, addition of NAD(P)H resulted in 2-3-fold increase in activity. Chromate reductase showed optimum activity at 28 deg. C and pH 7.

  3. DNA Repair Defects and Chromosomal Aberrations

    Science.gov (United States)

    Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

  4. Chromaticity decay due to superconducting dipoles on the injection plateau of the Large Hadron Collider

    CERN Document Server

    Aquilina, N; Sammut, N; Strzeclzyk, M; Todesco, E

    2012-01-01

    It is well known that in a superconducting accelerator a significant chromaticity drift can be induced by the decay of the sextupolar component of the main dipoles. In this paper we give a brief overview of what was expected for the Large Hadron Collider on the grounds of magnetic measurements of individual dipoles carried out during the production. According to this analysis, the decay time constants were of the order of 200 s: since the injection in the LHC starts at least 30 minutes after the magnets are at constant current, the dynamic correction of this effect was not considered to be necessary. The first beam measurements of chromaticity showed significant decay even after few hours. For this reason, a dynamic correction of decay on the injection plateau was implemented based on beam measurements. This means that during the injection plateau the sextupole correctors are powered with a varying current to cancel out the decay of the dipoles. This strategy has been implemented successfully. A similar pheno...

  5. High order aberrations calculation of a hexapole corrector using a differential algebra method

    Science.gov (United States)

    Kang, Yongfeng; Liu, Xing; Zhao, Jingyi; Tang, Tiantong

    2017-02-01

    A differential algebraic (DA) method is proved as an unusual and effective tool in numerical analysis. It implements conveniently differentiation up to arbitrary high order, based on the nonstandard analysis. In this paper, the differential algebra (DA) method has been employed to compute the high order aberrations up to the fifth order of a practical hexapole corrector including round lenses and hexapole lenses. The program has been developed and tested as well. The electro-magnetic fields of arbitrary point are obtained by local analytic expressions, then field potentials are transformed into new forms which can be operated in the DA calculation. In this paper, the geometric and chromatic aberrations up to fifth order of a practical hexapole corrector system are calculated by the developed program.

  6. Chromate Binding and Removal by the Molybdate-Binding Protein ModA.

    Science.gov (United States)

    Karpus, Jason; Bosscher, Michael; Ajiboye, Ifedayo; Zhang, Liang; He, Chuan

    2017-02-02

    Effective and cheap methods and techniques for the safe removal of hexavalent chromate from the environment are in increasingly high demand. High concentrations of hexavalent chromate have been shown to have numerous harmful effects on human biology. We show that the E. coli molybdate-binding protein ModA is a genetically encoded tool capable of removing chromate from aqueous solutions. Although previously reported to not bind chromate, we show that ModA binds chromate tightly and is capable of removing chromate to levels well below current US federal standards.

  7. Chromatically unique 6-bridge graph theta(a,a,a,b,b,c

    Directory of Open Access Journals (Sweden)

    N.S.A. Karim

    2016-04-01

    Full Text Available For a graph $G$, let $P(G,\\lambda$ denote the chromatic polynomial of $G$. Two graphs $G$ and $H$ are chromatically equivalent if they share the same chromatic polynomial. A graph $G$ is chromatically unique if for any graph chromatically equivalent to $G$ is isomorphic to $G$. In this paper, the chromatically unique of a new family of 6-bridge graph $\\theta(a,a,a,b,b,c$ where $2\\le a\\le b\\le c$ is investigated.

  8. Color constancy through inverse-intensity chromaticity space

    Science.gov (United States)

    Tan, Robby T.; Nishino, Ko; Ikeuchi, Katsushi

    2004-03-01

    Existing color constancy methods cannot handle both uniformly colored surfaces and highly textured surfaces in a single integrated framework. Statistics-based methods require many surface colors and become error prone when there are only a few surface colors. In contrast, dichromatic-based methods can successfully handle uniformly colored surfaces but cannot be applied to highly textured surfaces, since they require precise color segmentation. We present a single integrated method to estimate illumination chromaticity from single-colored and multicolored surfaces. Unlike existing dichromatic-based methods, the proposed method requires only rough highlight regions without segmenting the colors inside them. We show that, by analyzing highlights, a direct correlation between illumination chromaticity and image chromaticity can be obtained. This correlation is clearly described in ``inverse-intensity chromaticity space,'' a novel two-dimensional space that we introduce. In addition, when Hough transform and histogram analysis is utilized in this space, illumination chromaticity can be estimated robustly, even for a highly textured surface.

  9. Aberration corrected STEM to study an ancient hair dyeing formula

    Science.gov (United States)

    Patriarche, G.; Van Elslande, E.; Castaing, J.; Walter, P.

    2014-05-01

    Lead-based chemistry was initiated in ancient Egypt for cosmetic preparation more than 4000 years ago. Here, we study a hair-dyeing recipe using lead salts described in text since Greco-Roman times. We report direct evidence about the shape and distribution of PbS nanocrystals that form within the hair during blackening.

  10. Higher order aberration comparison between two aspherical intraocular lenses: MC6125AS and Akreos advanced optics

    Institute of Scientific and Technical Information of China (English)

    Mohammad; Taher; Rajabi; Sara; Korouji; Mahgol; Farjadnia; Mohammad; Naderan; Mohammad; Bagher; Rajabi; Bahram; Khosravi; Seyed; Mehdi; Tabatabaie

    2015-01-01

    AIM: To compare higher order aberrations in two aspherical intraocular lenses(IOLs): Akreos advanced optics(AO) and Dr. Schmidt Microcrystalline 6125 aspheric anterior surface(MC6125AS) with each other. METHODS: Forty eyes of 39 patients underwent phacoemulsification and Akreos AO and MC6125 AS were implanted in their eyes in a random manner. Three months post-operatively, higher order aberrations including spherical aberration, coma aberration, and total aberrations were measured and compared.RESULTS: The total aberration was 0.24±0.17 in eyes with Dr. Schmidt and 0.20 ±0.01 in eyes with Akreos AO(P =0.361). The mean of coma aberration was 0.17 ±0.21 and 0.09 ±0.86 in Dr. Schmidt and Akreos lenses,respectively(P =0.825). Total spherical aberration was almost the same in both groups(mean: 0.05, P =0.933).Best corrected visual acuity in Akreos AO(0.10±0.68) and Dr. Schmidt(0.09±0.67) did not differ significantly(P =0.700). CONCLUSION: There is no statistically significant difference in the higher order aberrations between these two aspherical lenses.

  11. Chromatic effects of the atmosphere on astronomical adaptive optics.

    Science.gov (United States)

    Devaney, Nicholas; Goncharov, Alexander V; Dainty, J Christopher

    2008-03-10

    The atmosphere introduces chromatic errors that may limit the performance of adaptive optics (AO) systems on large telescopes. Various aspects of this problem have been considered in the literature over the past two decades. It is necessary to revisit this problem in order to examine the effect on currently planned systems, including very high-order AO on current 8-10 m class telescopes and on future 30-42 m extremely large telescopes. We review the literature on chromatic effects and combine an analysis of all effects in one place. We examine implications for AO and point out some effects that should be taken into account in the design of future systems. In particular we show that attention should be paid to chromatic pupil shifts, which may arise in components such as atmospheric dispersion compensators.

  12. Fabrication of anodic aluminum oxide with incorporated chromate ions

    Science.gov (United States)

    Stępniowski, Wojciech J.; Norek, Małgorzata; Michalska-Domańska, Marta; Bombalska, Aneta; Nowak-Stępniowska, Agata; Kwaśny, Mirosław; Bojar, Zbigniew

    2012-10-01

    The anodization of aluminum in 0.3 M chromic acid is studied. The influence of operating conditions (like anodizing voltage and electrolyte's temperature) on the nanoporous anodic aluminum oxide geometry (including pore diameter, interpore distance, the oxide layer thickness and pores density) is thoroughly investigated. The results revealed typical correlations of the anodic alumina nanopore geometry with operating conditions, such as linear increase of pore diameter and interpore distance with anodizing voltage. The anodic aluminum oxide is characterized by a low pores arrangement, as determined by Fast Fourier transforms analyses of the FE-SEM images, which translates into a high concentration of oxygen vacancies. Moreover, an optimal experimental condition where chromate ions are being successfully incorporated into the anodic alumina walls, have been determined: the higher oxide growth rate the more chromate ions are being trapped. The trapped chromate ions and a high concentration of oxygen vacancies make the anodic aluminum oxide a promising luminescent material.

  13. Aberration of Light and Motion of Real Particle

    CERN Document Server

    Klacka, J

    2000-01-01

    Correct and complete (to terms of $\\vec{v} / c$ -- $\\vec{v}$ is particle's velocity, $c$ is the speed of light) derivation of equation of motion for real dust particle under the action of electromagnetic radiation is derived. The effect of aberration of light is used. Equation of motion is expressed in terms of particle's optical properties, standardly used in optics for stationary particles.

  14. RECURSIVE FORMULA FOR CALCULATING THE CHROMATIC POLYNOMIAL OF A GRAPH BY VERTEX DELETION

    Institute of Scientific and Technical Information of China (English)

    许进

    2004-01-01

    A new recursive vertex-deleting formula for the computation of the chromatic polynomial of a graph is obtained in this paper. This algorithm is not only a good tool for further studying chromatic polynomials but also the fastest among all the algorithms for the computation of chromatic polynomials.

  15. Using geometric algebra to study optical aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hanlon, J.; Ziock, H.

    1997-05-01

    This paper uses Geometric Algebra (GA) to study vector aberrations in optical systems with square and round pupils. GA is a new way to produce the classical optical aberration spot diagrams on the Gaussian image plane and surfaces near the Gaussian image plane. Spot diagrams of the third, fifth and seventh order aberrations for square and round pupils are developed to illustrate the theory.

  16. Electrochemical reduction of dilute chromate solutions on carbon felt electrodes

    NARCIS (Netherlands)

    Frenzel, Ines; Holdik, Hans; Barmashenko, Vladimir; Stamatialis, Dimitrios F.; Wessling, Matthias

    2006-01-01

    Carbon felt is a potential material for electrochemical reduction of chromates. Very dilute solutions may be efficiently treated due to its large specific surface area and high porosity. In this work, the up-scaling of this technology is investigated using a new type of separated cell and once-throu

  17. CHROMATIC NUMBER OF SQUARE OF MAXIMAL OUTERPLANAR GRAPHS

    Institute of Scientific and Technical Information of China (English)

    Luo Xiaofang

    2007-01-01

    Let χ(G2) denote the chromatic number of the square of a maximal outerplanar graph G and Q denote a maximal outerplanar graph obtained by adding three chords and χ(G2) = Δ + 2 if and only if G is Q, where Δ represents the maximum degree of G.

  18. Chromatic-Spatial Vision of the Aging Eye

    Science.gov (United States)

    Werner, John S.; Delahunt, Peter B.; Hardy, Joseph L.

    2004-07-01

    The human visual system undergoes continuous anatomical, physiological and functional changes throughout the life span. There is also continuous change in the spectral distribution and intensity of light reaching the retina from infancy through senescence, primarily due to changes in the absorption of short-wave light by the lens. Despite these changes in the retinal stimulus and the signals leaving the retina for perceptual analysis, color appearance is relatively stable during aging as measured by broadband reflective or self-luminous samples, the wavelengths of unique blue and yellow, and the achromatic locus. Measures of ocular media density for younger and older observers show, indeed, that color appearance is independent of ocular media density. This may be explained by a renormalization process that was demonstrated by measuring the chromaticity of the achromatic point before and after cataract surgery. There was a shift following cataract surgery (removal of a brunescent lens) that was initially toward yellow in color space, but over the course of months, drifted back in the direction of the achromatic point before surgery. The spatial characteristics of color mechanisms were quantified for younger and older observers in terms of chromatic perceptive fields and the chromatic contrast sensitivity functions. Younger and older observers differed with small spots or with chromatic spatial gratings near threshold, but there were no significant differences with larger spots or suprathreshold spatial gratings.

  19. Chromatic Enumeration for Singular Maps on the Klein Bottle

    Institute of Scientific and Technical Information of China (English)

    李赵祥; 刘彦佩

    2002-01-01

    A map is singular if each edge is on the same face on a surface (i.e.,it has only one face on a surface).In this paper we present the chromatic enumeration for rooted singular maps on the Klein bottle.

  20. THE LIST CHROMATIC NUMBERS OF SOME PLANAR GRAPHS

    Institute of Scientific and Technical Information of China (English)

    LǖEnyue; ZhangKemin

    1999-01-01

    In this paper, the choosability of outerplanar graphs, 1-tree and strong 1-outerplanargraphs have been described completely. A precise upper bound of the list chromatic number of 1-outerplanar graphs is given, and that every 1-outerplanar graph with girth at least 4 is 3-choosable is proved.

  1. Analysis of nodal aberration properties in off-axis freeform system design.

    Science.gov (United States)

    Shi, Haodong; Jiang, Huilin; Zhang, Xin; Wang, Chao; Liu, Tao

    2016-08-20

    Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs). It has been demonstrated that adding Zernike terms, up to nine, to the off-axis system modifies the nodal locations, but the field dependence of the third-order aberration does not change. On this basis, an off-axis two-mirror freeform system with 500 mm effective focal length (EFL) and 300 mm entrance pupil diameter (EPD) working in long-wave infrared is designed. The field constant aberrations induced by surface tilting are corrected by selecting specific Zernike terms. The design results show that the nodes of third-order astigmatism and coma move back into the field of view (FOV). The modulation transfer function (MTF) curves are above 0.4 at 20 line pairs per millimeter (lp/mm) which meets the infrared reconnaissance requirement. This work provides essential insight and guidance for aberration correction in off-axis freeform system design.

  2. Assessment of Systematic Chromatic Errors that Impact Sub-1% Photometric Precision in Large-Area Sky Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Li, T. S. [et al.

    2016-05-27

    Meeting the science goals for many current and future ground-based optical large-area sky surveys requires that the calibrated broadband photometry is stable in time and uniform over the sky to 1% precision or better. Past surveys have achieved photometric precision of 1-2% by calibrating the survey's stellar photometry with repeated measurements of a large number of stars observed in multiple epochs. The calibration techniques employed by these surveys only consider the relative frame-by-frame photometric zeropoint offset and the focal plane position-dependent illumination corrections, which are independent of the source color. However, variations in the wavelength dependence of the atmospheric transmission and the instrumental throughput induce source color-dependent systematic errors. These systematic errors must also be considered to achieve the most precise photometric measurements. In this paper, we examine such systematic chromatic errors using photometry from the Dark Energy Survey (DES) as an example. We define a natural magnitude system for DES and calculate the systematic errors on stellar magnitudes, when the atmospheric transmission and instrumental throughput deviate from the natural system. We conclude that the systematic chromatic errors caused by the change of airmass in each exposure, the change of the precipitable water vapor and aerosol in the atmosphere over time, and the non-uniformity of instrumental throughput over the focal plane, can be up to 2% in some bandpasses. We compare the calculated systematic chromatic errors with the observed DES data. For the test sample data, we correct these errors using measurements of the atmospheric transmission and instrumental throughput. The residual after correction is less than 0.3%. We also find that the errors for non-stellar objects are redshift-dependent and can be larger than those for stars at certain redshifts.

  3. Study on the design and Zernike aberrations of a segmented mirror telescope

    Institute of Scientific and Technical Information of China (English)

    Jiang Zhen-Yu; Li Lin; Huang Yi-Fan

    2009-01-01

    The segmented mirror telescope is widely used. The aberrations of segmented mirror systems are different from single mirror systems. This paper uses the Fourier optics theory to analyse the Zernike aberrations of segmented mirror systems. It concludes that the Zernike aberrations of segmented mirror systems obey the linearity theorem. The design of a segmented space telescope and segmented schemes are discussed, and its optical model is constructed. The computer simulation experiment is performed with this optical model to verify the suppositions. The experimental results confirm the correctness of the model.

  4. Phase Aberrations in Diffraction Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  5. Porous silicon optical template for determination of chromatic dispersion of transparent liquid mixture

    Science.gov (United States)

    Cafe, Arven I.; Lopez, Joybelle; Lopez, Lorenzo; Faustino, Maria Angela; Mabilangan, Arvin; Salvador, Arnel; Somintac, Armando

    2017-03-01

    Porous silicon was fabricated through electrochemical etching and is used as an optical template for liquid sensing application. Using reflectance spectroscopy, change in optical properties such as refractive index and reflectivity upon liquid introduction were obtained. Chromatic dispersion of porous silicon upon detection of transparent liquids such as absolute ethanol, methanol, 2-propanol and distilled water were determined for spectral range 450nm to 1100nm. Mixture of the organic transparent liquid and water was also tested. In this study, porosity and liquid's concentration were varied to establish the sensitivity of detection. Expected ideal values were also simulated for comparison and correction factor computation. Results provide calibration basis for water quality assessment, environmental monitoring, and diagnostic application.

  6. Ce对玻璃光谱曲线及色度指标的影响%Influence of Cerium on the Spectra and Chromaticity of Glass

    Institute of Scientific and Technical Information of China (English)

    代丽萍; 白晓华

    2011-01-01

    A golden glass was produced by combined coloration of CeO2 and TiO2. The amount of CeO2 additive and redox of the glass batch affect the optical properties and chromaticity of glass so that large chromatic - aberration appears. By changing Ce addition and redox agent in glass batch a splendid golden glass sample was obtained. The spectra and chromaticity analysis was carried out by using CARY500 spectrophotometer. Results indicate that the optical properties and chromaticity of this new golden yellow glass are highly dependent on those factors, such as, amount of colourants, oxidation -reduction of glass batch and addition of fluorite.%用CeO2及TiO2混合着色可以生产金黄色的玻璃,铈的用量及玻璃配合料氧化还原性都容易造成玻璃光学指标及色度指标的改变,使玻璃产生较大的色差.通过改变玻璃中铈的用量和氧化还原剂用量熔制玻璃样片,然后用CARY500分光光度计对玻璃样片进行光度及色度指标分析.结果表明:着色剂的用量、配合料的氧化还原性、萤石的添加量对玻璃的光学指标及色度指标都有较大影响.

  7. Correlations between corneal and total wavefront aberrations

    Science.gov (United States)

    Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo

    2002-06-01

    Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.

  8. Chromosome aberrations induced by zebularine in triticale.

    Science.gov (United States)

    Ma, Xuhui; Wang, Qing; Wang, Yanzhi; Ma, Jieyun; Wu, Nan; Ni, Shuang; Luo, Tengxiao; Zhuang, Lifang; Chu, Chenggen; Cho, Seong-Woo; Tsujimoto, Hisashi; Qi, Zengjun

    2016-07-01

    Chromosome engineering is an important approach for generating wheat germplasm. Efficient development of chromosome aberrations will facilitate the introgression and application of alien genes in wheat. In this study, zebularine, a DNA methylation transferase inhibitor, was successfully used to induce chromosome aberrations in the octoploid triticale cultivar Jinghui#1. Dry seeds were soaked in zebularine solutions (250, 500, and 750 μmol/L) for 24 h, and the 500 μmol/L treatment was tested in three additional treatment times, i.e., 12, 36, and 48 h. All treatments induced aberrations involving wheat and rye chromosomes. Of the 920 cells observed in 67 M1 plants, 340 (37.0%) carried 817 aberrations with an average of 0.89 aberrations per cell (range: 0-12). The aberrations included probable deletions, telosomes and acentric fragments (49.0%), large segmental translocations (28.9%), small segmental translocations (17.1%), intercalary translocations (2.6%), long chromosomes that could carry more than one centromere (2.0%), and ring chromosomes (0.5%). Of 510 M2 plants analyzed, 110 (21.6%) were found to carry stable aberrations. Such aberrations included 79 with varied rye chromosome numbers, 7 with wheat and rye chromosome translocations, 15 with possible rye telosomes/deletions, and 9 with complex aberrations involving variation in rye chromosome number and wheat-rye translocations. These indicated that aberrations induced by zebularine can be steadily transmitted, suggesting that zebularine is a new efficient agent for chromosome manipulation.

  9. Spatial Light Modulator for wavefront correction

    CERN Document Server

    Vyas, Akondi; Banyal, Ravinder Kumar; Prasad, B Raghavendra

    2009-01-01

    We present a liquid crystal method of correcting the phase of an aberrated wavefront using a spatial light modulator. A simple and efficient lab model has been demonstrated for wavefront correction. The crux of a wavefront correcting system in an adaptive optics system lies in the speed and the image quality that can be achieved. The speeds and the accuracy of wavefront representation using Zernike polynomials have been presented using a very fast method of computation.

  10. Detection of Perturbation in Chromatic and Luminance-Defined Lines and Square-Waves

    Directory of Open Access Journals (Sweden)

    R.J Sharman

    2014-08-01

    Full Text Available The composition of a stimulus may affect how cues are combined. A thin luminance ring surrounding a uniform chromatic test facilitates contrast detection as much as a uniform luminance pedestal (Cole, Stromeyer & Kronauer, 1990, JOSA A, 7(1, 128-140. This could suggest that there is a specific facilitatory relationship between luminance lines and chromatic edges that is not present in other combinations. Therefore, combining luminance lines and chromatic edges could also improve performance in edge detection tasks. Here we use a novel task, perturbation detection, target gratings were sinusoidally perturbed in space and subjects were asked to detect which of two stimuli was not straight. Perturbation thresholds, were measured for chromatic and luminance defined line and square-wave gratings alone and in combination. The introduction of a line mask produced increased thresholds in all conditions. However, the introduction of a chromatic square-wave mask improved perception of perturbation in luminance lines, whereas the introduction of a luminance defined square-wave mask has little effect on the perturbation thresholds for chromatic lines. This could suggest that when a luminance line is presented with a chromatic edge, such as the chromatic boundaries in a square-wave grating, the chromatic information becomes ‘tied’ to the luminance information. The perceived location of the chromatic edge may be determined by the location of the luminance line.

  11. Chromatic Dispersion Monitoring Method Based on Phase Shift Technique

    Institute of Scientific and Technical Information of China (English)

    L(U) Chengang; WU Xing; ZENG Lizhu; QIN Yifan; ZU Peng; HU Zhixiong; GE Chunfeng

    2007-01-01

    The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1 532. 16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1 549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1 310 nm, a 1 310/1 550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).

  12. Towards Bio-Inspired Chromatic Behaviours in Surveillance Robots

    Directory of Open Access Journals (Sweden)

    Sampath Kumar Karutaa Gnaniar

    2016-09-01

    Full Text Available The field of Robotics is ever growing at the same time as posing enormous challenges. Numerous works has been done in biologically inspired robotics emulating models, systems and elements of nature for the purpose of solving traditional robotics problems. Chromatic behaviours are abundant in nature across a variety of living species to achieve camouflage, signaling, and temperature regulation. The ability of these creatures to successfully blend in with their environment and communicate by changing their colour is the fundamental inspiration for our research work. In this paper, we present dwarf chameleon inspired chromatic behaviour in the context of an autonomous surveillance robot, “PACHONDHI”. In our experiments, we successfully validated the ability of the robot to autonomously change its colour in relation to the terrain that it is traversing for maximizing detectability to friendly security agents and minimizing exposure to hostile agents, as well as to communicate with fellow cooperating robots.

  13. Image aberrations in optical three-dimensional measurement systems with fringe projection.

    Science.gov (United States)

    Brakhage, Peter; Notni, Gunther; Kowarschik, Richard

    2004-06-01

    In optical shape measurement systems, systematic errors appear as a result of imaging aberrations of the lens assemblies in the cameras and projectors. A mathematical description of this effect is intended to correct the whole measurement area with a few independent coefficients. We apply the ideas of photogrammetry to one- and two-dimensional fringe projection techniques. We also introduce some new terms for close-range applications and telecentric objectives. Further, an algorithm for distance-dependent corrections is introduced. Also, we describe a new method with which to determine coefficients of aberration with an optimization-based method.

  14. The total chromatic number of regular graphs of high degree

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The total chromatic number χT (G) of a graph G is the minimum number of colors needed to color the edges and the vertices of G so that incident or adjacent elements have distinct colors. We show that if G is a regular graph and d(G) 32 |V (G)| + 263 , where d(G) denotes the degree of a vertex in G, then χT (G) d(G) + 2.

  15. Bounds for the harmonious chromatic number of a graph

    OpenAIRE

    Krasikov, I.; Y. Roditty

    1994-01-01

    The upper bound for the harmonious chromatic number of a graph given by Zhikang Lu and by C. McDiarmid and Luo Xinhua, independently (Journal of Graph Theory, 1991, pp. 345-347 and 629-636) and the lower bound given by D. G. Beane, N. L. Biggs, and B. J. Wilson (Journal of Graph Theory, 1989, pp. 291-298) are improved.

  16. "Tilt" in color space: Hue changes induced by chromatic surrounds.

    Science.gov (United States)

    Klauke, Susanne; Wachtler, Thomas

    2015-01-01

    The perceived color of a chromatic stimulus is influenced by the chromaticity of its surround. To investigate these influences along the dimension of hue, we measured hue changes induced in stimuli of different hues by isoluminant chromatic surrounds. Generally, induced hue changes were directed in color space away from the hue of the inducing surround and depended on the magnitude on the hue difference between stimulus and surround. With increasing difference in hue between stimulus and surround, induced hue changes increased up to a maximum and then decreased for larger differences. This qualitative pattern was similar for different inducers, but quantitatively, induction was weaker along some directions in cone-opponent color space than along other directions. The strongest induction effects were found along an oblique, blue-yellow axis that corresponds to the daylight axis. The overall pattern of the induction effect shows similarities to the well-known tilt effect, where shifts in perceived angle of oriented stimuli are induced by oriented surrounds. This suggests analogous neural representations and similar mechanisms of contextual processing for different visual features such as orientation and color.

  17. Optics Corrections with LOCO in the Fermilab Booster

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Cheng-Yang [Fermilab; Prost, Lionel [Fermilab; Seiya, Kiyomi [Fermilab; Triplett, A. Kent [Fermilab

    2016-06-01

    The optics of the Fermilab Booster has been corrected with LOCO (Linear Optics from Closed Orbits). However, the first corrections did not show any improvement in capture efficiency at injection. A detailed analysis of the results showed that the problem lay in the MADX optics file. Both the quadrupole and chromatic strengths were originally set as constants independent of beam energy. However, careful comparison between the measured and calculated tunes and chromatcity show that these strengths are energy dependent. After the MADX model was modified with these new energy dependent strengths, the LOCO corrected lattice has been applied to Booster. The effect of the corrected lattice will be discussed here.

  18. Chromate Reduction in Serratia marcescens Isolated from Tannery Effluent and Potential Application for Bioremediation of Chromate Pollution

    Directory of Open Access Journals (Sweden)

    M.A. Mondaca

    2002-01-01

    Full Text Available Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI and Cr(III are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI to Cr(III, and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010 cfu attached per milligram of activated carbon. These findings demonstrate that immobilized S. marcescens might be used in industrial waste treatment processes.

  19. Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus

    NARCIS (Netherlands)

    Nio, YK; Jansonius, NM; Wijdh, RHJ; Beekhuis, WH; Worst, JGF; Noorby, S; Kooijman, AC

    2003-01-01

    Purpose. To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. Setting: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. Methods: Three groups of patients with low myopia correction (spectacl

  20. A FrFT based method for measuring chromatic dispersion and SPM in optical fibers

    Science.gov (United States)

    Yang, Aiying; Liu, Xiang; Chen, Xiaoyu

    2017-03-01

    A fractional Fourier transformation based method is proposed to blindly estimate the chromatic dispersion and self phase modulation in optical fibers. The experimental results demonstrate that up to 20,000 ps/nm accumulative chromatic dispersion of a fiber link is measured with the error less than 0.8%. If the chromatic dispersion is compensated by multiplying an opposite chromatic dispersion function in frequency domain, the 1st order chirp parameter caused by SPM in an optical fiber communication system can be measured by fractional Fourier transformation based method, i.e. the accumulative SPM of a fiber link can be quantitatively measured. The results of equalizing chromatic dispersion and self phase modulation in an optical fiber communication system demonstrated that the FrFT based method is promising to blindly monitor and equalize the chromatic dispersion and SPM of the fiber link in an optical network with dynamical routing function.

  1. Error Correction for the JLEIC Ion Collider Ring

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Guohui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Morozov, Vasiliy [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lin, Fanglei [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Pilat, Fulvia C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Nosochkov, Yuri [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, Min-Huey [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-05-01

    The sensitivity to misalignment, magnet strength error, and BPM noise is investigated in order to specify design tolerances for the ion collider ring of the Jefferson Lab Electron Ion Collider (JLEIC) project. Those errors, including horizontal, vertical, longitudinal displacement, roll error in transverse plane, strength error of main magnets (dipole, quadrupole, and sextupole), BPM noise, and strength jitter of correctors, cause closed orbit distortion, tune change, beta-beat, coupling, chromaticity problem, etc. These problems generally reduce the dynamic aperture at the Interaction Point (IP). According to real commissioning experiences in other machines, closed orbit correction, tune matching, beta-beat correction, decoupling, and chromaticity correction have been done in the study. Finally, we find that the dynamic aperture at the IP is restored. This paper describes that work.

  2. Binocular adaptive optics visual simulator: understanding the impact of aberrations on actual vision

    Science.gov (United States)

    Fernández, Enrique J.; Prieto, Pedro M.; Artal, Pablo

    2010-02-01

    A novel adaptive optics system is presented for the study of vision. The apparatus is capable for binocular operation. The binocular adaptive optics visual simulator permits measuring and manipulating ocular aberrations of the two eyes simultaneously. Aberrations can be corrected, or modified, while the subject performs visual testing under binocular vision. One of the most remarkable features of the apparatus consists on the use of a single correcting device, and a single wavefront sensor (Hartmann-Shack). Both the operation and the total cost of the instrument largely benefit from this attribute. The correcting device is a liquid-crystal-on-silicon (LCOS) spatial light modulator. The basic performance of the visual simulator consists in the simultaneous projection of the two eyes' pupils onto both the corrector and sensor. Examples of the potential of the apparatus for the study of the impact of the aberrations under binocular vision are presented. Measurements of contrast sensitivity with modified combinations of spherical aberration through focus are shown. Special attention was paid on the simulation of monovision, where one eye is corrected for far vision while the other is focused at near distance. The results suggest complex binocular interactions. The apparatus can be dedicated to the better understanding of the vision mechanism, which might have an important impact in developing new protocols and treatments for presbyopia. The technique and the instrument might contribute to search optimized ophthalmic corrections.

  3. Chromatic Sums of Biloopless Nonseparable Near-Triangulations on the Projective Plane

    Institute of Scientific and Technical Information of China (English)

    Zhao-xiang Li; Yan-pei Liu; Bing-feng Si

    2013-01-01

    In this paper,the chromatic sum functions of rooted biloopless nonseparable near-triangulations on the sphere and the projective plane are studied.The chromatic sum function equations of such maps are obtained.From the chromatic sum equations of such maps,the enumerating function equations of such maps are derived.An asymptotic evaluation and some explicit expression of enumerating functions are also derived.

  4. Aberrations of Gradient-Index Lenses.

    Science.gov (United States)

    Matthews, A. L.

    Available from UMI in association with The British Library. In this thesis, the primary aberrations of lenses with a radial focussing gradient-of-index are analysed. Such a lens has a refractive index profile which decreases continuously and radially outward from the optical axis, so that the surfaces of constant refractive index are circular cylinders which are coaxial with the optical axis. Current applications of these lenses include photocopiers, medical endoscopes, telecommunications systems and compact disc systems. Closed formulae for the primary wavefront aberrations for a gradient-index lens with curved or plane entry and exit faces are obtained from the differential equations of such a lens to assess the primary transverse ray aberrations that it introduces. Identical expressions are then obtained by using the difference in optical path length produced between two rays by the lens. This duplication of the derivations of the primary wavefront aberrations acts as a confirmation of the validity of the expressions. One advantage of these equations is that the contributions due to the primary spherical aberration, coma, astigmatism, field curvature and distortion can be assessed individually. A Fortran 77 program has been written to calculate each of these individual contributions, the total primary wavefront aberrations and the primary transverse ray aberrations. Further confirmation of the validity of the expressions is obtained by using this program to show that the coma and distortion were both zero for fully symmetric systems working at unit magnification. The program is then used to assess the primary wavefront aberrations for a gradient-index lens which is currently of interest to the telecommunications industry. These results are compared with values obtained using a finite ray-tracing program for the total wavefront aberrations. This shows that the primary wavefront aberrations are the completely dominant contribution to the total wavefront

  5. Removal of chromate in a permeable reactive barrier using zero-valent iron

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Locht, T

    2002-01-01

    Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces...

  6. Definition and measurement of the beam propagation factor M2 for chromatic laser beams

    Institute of Scientific and Technical Information of China (English)

    Tao Fang; Xin Ye; Jinfu Niu; Jianqiu Xu

    2006-01-01

    The concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as same as that of monochromatic beams. A simple method to measure the chromatic beam factor M2 is demonstrated. The chromatic factor M2 is found invariable while the laser beam propagates through the dispersion-free ABCD system.

  7. Performance Comparison of Steam-Based and Chromate Conversion Coatings on Aluminum Alloy 6060

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    In this study, oxide layers generated on aluminum alloy 6060(UNS A96060) using a steam-based process were compared with conventional chromate and chromate-phosphate conversion coatings. Chemical composition and microstructure of the conversion coatings were investigated and their corrosion...... performance was evaluated using potentio dynamic polarization, acetic acid salt spray, and filiform corrosion testing of powder coated specimens. The steam-based process resulted in homogenous growth of oxide layer and superior coverageover intermetallic particles when compared to chromate-based conversion...... coatings. The coating formed by steam showed improved corrosion resistance, while adhesion to powder coatingand filiform corrosion was comparable with chromate conversion coatings....

  8. Chromatic Sums of Nonseparable Near-Triangulations on the Projective Plane

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiang LI; Wei HE

    2012-01-01

    In this paper,we study the chromatic sum functions of rooted nonseparable neartriangulations on the sphere and the projective plane.The chromatic sum function equations of such maps are obtained.From the chromatic sum equations of such maps,the enumerating function equations of such maps are derived.Applying chromatic sum theory,the enumerating problem of different sorts maps can be studied,and a new method of enumeration can be obtained.Moreover,an asymptotic evaluation and some explicit expression of enumerating functions are also derived.

  9. Reduction of chromatic dispersion due to coupling for synchronized-router-based flat-passband filter using multiple-input arrayed waveguide grating.

    Science.gov (United States)

    Maru, Koichi; Fujii, Yusaku

    2009-11-23

    An approach to reducing the chromatic dispersion due to coupling between input waveguides before the input slab for a synchronized-router-based flat-passband filter using a multiple-input arrayed waveguide grating (AWG) is proposed. The proposed method uses phase compensation at the waveguide array of the AWG by correction of waveguide lengths. The characteristics of the flat-passband filter that consists of a multiple-input AWG combined with cascaded Mach-Zehnder interferometers (MZIs) are simulated using a theoretical model of the multiple-input AWG based on Fourier optics and the coupled-mode theory. The simulation result reveals that the chromatic dispersion within the passband can be significantly reduced by using phase compensation and additional dummy waveguides at the input just before the slab.

  10. Aberration coefficients of curved holographic optical elements

    Science.gov (United States)

    Verboven, P. E.; Lagasse, P. E.

    1986-11-01

    A general formula is derived that gives all aberration terms of holographic optical elements on substrates of any shape. The spherical substrate shape and the planar substrate shape are treated as important special cases. A numerical example illustrates the need of including higher-order aberrations.

  11. Psychometric Characteristics of the Aberrant Behavior Checklist.

    Science.gov (United States)

    Aman, Michael G.; And Others

    1985-01-01

    Information is presented on the psychometric characteristics of the Aberrant Behavior Checklist, a measure of psychotropic drug effects. Internal consistency and test-retest reliability of the checklist appeared very good. Interrater reliability was generally in the moderate range. In general, validity was established for most Aberrant Behavior…

  12. Higher-Order Aberrations in Myopic Eyes

    Directory of Open Access Journals (Sweden)

    Farid Karimian

    2010-01-01

    Full Text Available Purpose: To evaluate the correlation between refractive error and higher-order aberrations (HOAs in patients with myopic astigmatism. Methods: HOAs were measured using the Zywave II aberrometer over a 6 mm pupil. Correlations between HOAs and myopia, astigmatism, and age were analyzed. Results: One hundred and twenty-six eyes of 63 subjects with mean age of 26.4±5.9 years were studied. Mean spherical equivalent refractive error and refractive astigmatism were -4.94±1.63 D and 0.96±1.06 D, respectively. The most common higher-order aberration was primary horizontal trefoil with mean value of 0.069±0.152 μm followed by spherical aberration (-0.064±0.130 μm and primary vertical coma (-0.038±0.148 μm. As the order of aberration increased from third to fifth, its contribution to total HOA decreased: 53.9% for third order, 31.9% for fourth order, and 14.2% for fifth order aberrations. Significant correlations were observed between spherical equivalent refractive error and primary horizontal coma (R=0.231, P=0.022, and root mean square (RMS of spherical aberration (R=0.213, P=0.031; between astigmatism and RMS of total HOA (R=0.251, P=0.032, RMS of fourth order aberration (R=0.35, P<0.001, and primary horizontal coma (R=0.314, P=0.004. Spherical aberration (R=0.214, P=0.034 and secondary vertical coma (R=0.203, P=0.031 significantly increased with age. Conclusion: Primary horizontal trefoil, spherical aberration and primary vertical coma are the predominant higher-order aberrations in eyes with myopic astigmatism.

  13. Some Aspects of Visual Processing Under Chromatic Adaptation.

    Science.gov (United States)

    Wilson, Julie Ann Frances

    Available from UMI in association with The British Library. This thesis describes the results of experimental investigations into three types of visual processing, namely, displacement thresholds for motion detection, speed and motion detection, and rod-cone interaction effects. Each of these topics is described separately. The overall conclusions and summary of this work with an emphasis on chromatic processes are presented in the last chapter. The introductory chapter of the thesis deals mostly with the anatomical and theoretical aspects of vision and the development of a system for the standardization of colour. Equations for the CIE colour and colour difference specifications are described. Equipment, optical apparatus and general calibration procedures for all the investigations are covered in Chapter Two. Displacement thresholds for motion detection under conditions of chromatic adaptation are the subject of Chapter Three. The smallest, continuous target displacement sufficient to cause a sensation of movement was measured under conditions of chromatic adaptation. The experiments were carried out for test target and background field wavelengths which selectively isolated the activity of the colour mechanisms of the human eye. In Chapter Four, two mechanisms capable of speed discrimination and motion detection are proposed. Experimental data are reported which suggest that the visual system employs both schemes. A small circular target of high retinal illuminance level can have a comet-like appearance when presented moving continuously with a speed as low as 0.2 deg/s. Data on the parametric properties of the 'comet effect' are presented in Chapter Five. Measurement of the target spectral irradiance levels sufficient to yield the 'comet effect' suggests that the lengthening of the circular target reflects a rod-cone interaction and therefore it may be due to unsuppressed, saturated rod responses at high retinal illuminance levels. Computational methods are

  14. Automated selection of LEDs by luminance and chromaticity coordinate

    CERN Document Server

    Fischer, Ulrich H P; Reinboth, Christian

    2010-01-01

    The increased use of LEDs for lighting purposes has led to the development of numerous applications requiring a pre-selection of LEDs by their luminance and / or their chromaticity coordinate. This paper demonstrates how a manual pre-selection process can be realized using a relatively simple configuration. Since a manual selection service can only be commercially viable as long as only small quantities of LEDs need to be sorted, an automated solution suggests itself. This paper introduces such a solution, which has been developed by Harzoptics in close cooperation with Rundfunk Gernrode. The paper also discusses current challenges in measurement technology as well as market trends.

  15. Chromatic Dispersion Compensation Using Photonic Crystal Fibers with Hexagonal Distribution

    Directory of Open Access Journals (Sweden)

    Erick E. Reyes-Vera

    2013-11-01

    Full Text Available In this paper we show various configurations of photonic crystal fiber with hexagonal holes distribution for compensation of chromatic dispersion in optical communications links. The vectorial finite element method with scattering boundary condition was used for the analysis of the fibers. From these results it was estimated variation of the dispersion and the dispersion slope with respect to change in the diameter of the holes in the microstructure. With the above was possible to obtain values of dispersion in the C and L bands of telecommunications close to -850 ps / nm * km, with confinement losses 10-3 dB / km

  16. Conditioned Poisson distributions and the concentration of chromatic numbers

    CERN Document Server

    Hartigan, John; Tatikonda, Sekhar

    2011-01-01

    The paper provides a simpler method for proving a delicate inequality that was used by Achlioptis and Naor to establish asymptotic concentration for chromatic numbers of Erdos-Renyi random graphs. The simplifications come from two new ideas. The first involves a sharpened form of a piece of statistical folklore regarding goodness-of-fit tests for two-way tables of Poisson counts under linear conditioning constraints. The second idea takes the form of a new inequality that controls the extreme tails of the distribution of a quadratic form in independent Poissons random variables.

  17. Aberration-Coreected Electron Microscopy at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Zhu,Y.; Wall, J.

    2008-04-01

    The last decade witnessed the rapid development and implementation of aberration correction in electron optics, realizing a more-than-70-year-old dream of aberration-free electron microscopy with a spatial resolution below one angstrom [1-9]. With sophisticated aberration correctors, modern electron microscopes now can reveal local structural information unavailable with neutrons and x-rays, such as the local arrangement of atoms, order/disorder, electronic inhomogeneity, bonding states, spin configuration, quantum confinement, and symmetry breaking [10-17]. Aberration correction through multipole-based correctors, as well as the associated improved stability in accelerating voltage, lens supplies, and goniometers in electron microscopes now enables medium-voltage (200-300kV) microscopes to achieve image resolution at or below 0.1nm. Aberration correction not only improves the instrument's spatial resolution but, equally importantly, allows larger objective lens pole-piece gaps to be employed thus realizing the potential of the instrument as a nanoscale property-measurement tool. That is, while retaining high spatial resolution, we can use various sample stages to observe the materials response under various temperature, electric- and magnetic- fields, and atmospheric environments. Such capabilities afford tremendous opportunities to tackle challenging science and technology issues in physics, chemistry, materials science, and biology. The research goal of the electron microscopy group at the Dept. of Condensed Matter Physics and Materials Science and the Center for Functional Nanomaterials, as well as the Institute for Advanced Electron Microscopy, Brookhaven National Laboratory (BNL), is to elucidate the microscopic origin of the physical- and chemical-behavior of materials, and the role of individual, or groups of atoms, especially in their native functional environments. We plan to accomplish this by developing and implementing various quantitative

  18. Population spherical aberration: associations with ametropia, age, corneal curvature, and image quality

    Directory of Open Access Journals (Sweden)

    Kingston AC

    2013-05-01

    Full Text Available Amanda C Kingston,1,2 Ian G Cox11Bausch + Lomb, Rochester, NY, USA; 2Department of Biomedical Engineering, University of Rochester, Rochester, NY, USAPurpose: The aim of this analysis was to determine the total ocular wavefront aberration values of a large phakic population of physiologically normal, ametropic eyes, gathered under the same clinical protocol using the same diagnostic wavefront sensor.Materials and methods: Studies were conducted at multiple sites in Asia, North America, Europe, and Australia. A Bausch + Lomb Zywave II Wavefront Aberrometer (Rochester, NY, USA was used to measure the lower and higher order aberrations of each eye. Data analysis was conducted using linear regression analysis to determine the relationship between total spherical aberration, ametropia, age, corneal curvature, and image quality.Results: Linear regression analysis showed no correlation (r = 0.0207, P = 0.4874 between degree of ametropia and the amount of spherical aberration. There was also no correlation when the population was stratified into myopic and hyperopic refractive groups (rm = 0.0529, Pm = 0.0804 and rh = 0.1572, Ph = 0.2754. There was a statistically significant and weak positive correlation (r = 0.1962, P < 0.001 between age and the amount of spherical aberration measured in the eye; spherical aberration became more positive with increasing age. Also, there was a statistically significant and moderately positive correlation (r = 0.3611, P < 0.001 with steepness of corneal curvature; spherical aberration became more positive with increasing power of the anterior corneal surface. Assessment of image quality using optical design software (Zemax™, Bellevue, WA, USA showed that there was an overall benefit in correcting the average spherical aberration of this population.Conclusion: Analysis of this dataset provides insights into the inherent spherical aberration of a typical phakic, pre-presbyopic, population and provides the ability to

  19. Chromosome aberration assays in Allium

    Energy Technology Data Exchange (ETDEWEB)

    Grant, W.F.

    1982-01-01

    The common onion (Allium cepa) is an excellent plant for the assay of chromosome aberrations after chemical treatment. Other species of Allium (A. cepa var. proliferum, A. carinatum, A. fistulosum and A. sativum) have also been used but to a much lesser extent. Protocols have been given for using root tips from either bulbs or seeds of Allium cepa to study the cytological end-points, such as chromosome breaks and exchanges, which follow the testing of chemicals in somatic cells. It is considered that both mitotic and meiotic end-points should be used to a greater extent in assaying the cytogenetic effects of a chemical. From a literature survey, 148 chemicals are tabulated that have been assayed in 164 Allium tests for their clastogenic effect. Of the 164 assays which have been carried out, 75 are reported as giving a positive reaction, 49 positive and with a dose response, 1 positive and temperature-related, 9 borderline positive, and 30 negative; 76% of the chemicals gave a definite positive response. It is proposed that the Allium test be included among those tests routinely used for assessing chromosomal damage induced by chemicals.

  20. Effects of Chromate and Non-Chromate Coating Systems on Environmentally Assisted Fatigue of an Aluminum Alloy

    Science.gov (United States)

    Schubbe, Joel J.; Westmoreland, Sophoria N.

    2014-10-01

    Fatigue crack growth testing of 2024-T3 Aluminum plate was performed using compact tension (CT) specimens with chromate and non-chromate primer paint systems to evaluate the effects of the coatings on fatigue crack growth rates. The tests were conducted in lab air and sea water environments for each of the coating systems. Standard E399 CT specimens were tested to determine the influence level of environmentally assisted cracking (corrosion fatigue) on crack growth rates and cyclic count to prescribed pre-crack and final crack lengths. Increasing stress range (Δ K) tests were conducted at 10 Hz in the range of 6.5 to 26.5 MPa. It was determined that the coated specimens exhibited a 12% shorter total life, on average, than the bare specimens for the lab air cases. In the case of salt water exposure, the coated specimens exhibited approximately 10% life increase over the bare specimens. The number of cycles to the 2.54 mm pre-crack length for the coated specimens was all less than the cycle count for the bare tests. In each case (coated or bare), there was an increased growth rate at the lower stress ranges in the salt water environment, with the chromate system case displaying the smallest change (increase). It can be concluded that the coated specimens initiate cracks and propagate faster than the bare specimens for short cracks at low stress range, but the environmental influence on the specimens is quickly overshadowed as the cracks elongate and the rate of growth increases. The coated specimens exhibited a higher total life cycle count to final crack length for this testing.

  1. Fluctuations in the prevalence of chromate allergy in Denmark and exposure to chrome-tanned leather

    DEFF Research Database (Denmark)

    Carøe, Caroline; Andersen, Klaus E; Thyssen, Jacob P;

    2010-01-01

    A recent Danish study showed a significant increase in the prevalence of chromate contact allergy after the mid-1990s, probably as a result of exposure to leather products.......A recent Danish study showed a significant increase in the prevalence of chromate contact allergy after the mid-1990s, probably as a result of exposure to leather products....

  2. Spatio-chromatic adaptation via higher-order canonical correlation analysis of natural images.

    Directory of Open Access Journals (Sweden)

    Michael U Gutmann

    Full Text Available Independent component and canonical correlation analysis are two general-purpose statistical methods with wide applicability. In neuroscience, independent component analysis of chromatic natural images explains the spatio-chromatic structure of primary cortical receptive fields in terms of properties of the visual environment. Canonical correlation analysis explains similarly chromatic adaptation to different illuminations. But, as we show in this paper, neither of the two methods generalizes well to explain both spatio-chromatic processing and adaptation at the same time. We propose a statistical method which combines the desirable properties of independent component and canonical correlation analysis: It finds independent components in each data set which, across the two data sets, are related to each other via linear or higher-order correlations. The new method is as widely applicable as canonical correlation analysis, and also to more than two data sets. We call it higher-order canonical correlation analysis. When applied to chromatic natural images, we found that it provides a single (unified statistical framework which accounts for both spatio-chromatic processing and adaptation. Filters with spatio-chromatic tuning properties as in the primary visual cortex emerged and corresponding-colors psychophysics was reproduced reasonably well. We used the new method to make a theory-driven testable prediction on how the neural response to colored patterns should change when the illumination changes. We predict shifts in the responses which are comparable to the shifts reported for chromatic contrast habituation.

  3. Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic disp...

  4. Chromatism compensation in wide-band nulling interferometry for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We introduce the concept of chromatism compensation in nulling interferometry that enables a high rejection ratio in a wide spectral band. Therefore the achromaticity condition considered in most nulling interferometers can be relaxed. We show that this chromatism compensation cannot be applied to a

  5. Assessment of Systematic Chromatic Errors that Impact Sub-1% Photometric Precision in Large-area Sky Surveys

    Science.gov (United States)

    Li, T. S.; DePoy, D. L.; Marshall, J. L.; Tucker, D.; Kessler, R.; Annis, J.; Bernstein, G. M.; Boada, S.; Burke, D. L.; Finley, D. A.; James, D. J.; Kent, S.; Lin, H.; Marriner, J.; Mondrik, N.; Nagasawa, D.; Rykoff, E. S.; Scolnic, D.; Walker, A. R.; Wester, W.; Abbott, T. M. C.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Capozzi, D.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Neilsen, E.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Vikram, V.; DES Collaboration

    2016-06-01

    Meeting the science goals for many current and future ground-based optical large-area sky surveys requires that the calibrated broadband photometry is both stable in time and uniform over the sky to 1% precision or better. Past and current surveys have achieved photometric precision of 1%-2% by calibrating the survey’s stellar photometry with repeated measurements of a large number of stars observed in multiple epochs. The calibration techniques employed by these surveys only consider the relative frame-by-frame photometric zeropoint offset and the focal plane position-dependent illumination corrections, which are independent of the source color. However, variations in the wavelength dependence of the atmospheric transmission and the instrumental throughput induce source color-dependent systematic errors. These systematic errors must also be considered to achieve the most precise photometric measurements. In this paper, we examine such systematic chromatic errors (SCEs) using photometry from the Dark Energy Survey (DES) as an example. We first define a natural magnitude system for DES and calculate the systematic errors on stellar magnitudes when the atmospheric transmission and instrumental throughput deviate from the natural system. We conclude that the SCEs caused by the change of airmass in each exposure, the change of the precipitable water vapor and aerosol in the atmosphere over time, and the non-uniformity of instrumental throughput over the focal plane can be up to 2% in some bandpasses. We then compare the calculated SCEs with the observed DES data. For the test sample data, we correct these errors using measurements of the atmospheric transmission and instrumental throughput from auxiliary calibration systems. The residual after correction is less than 0.3%. Moreover, we calculate such SCEs for Type Ia supernovae and elliptical galaxies and find that the chromatic errors for non-stellar objects are redshift-dependent and can be larger than those for

  6. Chromatic settings and the structural color constancy index.

    Science.gov (United States)

    Roca-Vila, Jordi; Parraga, C Alejandro; Vanrell, Maria

    2013-03-11

    Color constancy is usually measured by achromatic setting, asymmetric matching, or color naming paradigms, whose results are interpreted in terms of indexes and models that arguably do not capture the full complexity of the phenomenon. Here we propose a new paradigm, chromatic setting, which allows a more comprehensive characterization of color constancy through the measurement of multiple points in color space under immersive adaptation. We demonstrated its feasibility by assessing the consistency of subjects' responses over time. The paradigm was applied to two-dimensional (2-D) Mondrian stimuli under three different illuminants, and the results were used to fit a set of linear color constancy models. The use of multiple colors improved the precision of more complex linear models compared to the popular diagonal model computed from gray. Our results show that a diagonal plus translation matrix that models mechanisms other than cone gain might be best suited to explain the phenomenon. Additionally, we calculated a number of color constancy indices for several points in color space, and our results suggest that interrelations among colors are not as uniform as previously believed. To account for this variability, we developed a new structural color constancy index that takes into account the magnitude and orientation of the chromatic shift in addition to the interrelations among colors and memory effects.

  7. Chromatic, Phenolic and Antioxidant Properties of Sorghum bicolor Genotypes

    Directory of Open Access Journals (Sweden)

    José Juan LÓPEZ-CONTRERAS

    2015-12-01

    Full Text Available Chromatic, phenolic and antioxidant properties were evaluated in ten sorghum genotypes grown in Nuevo León, México. Lightness, Chroma and hue angle ranged from 64 to 83, 12 to 20 and 61 to 82 respectively, indicating that colour of the samples were located in the gray orange-yellow zone of the hue circle. Based on these results, samples were classified in three colour groups being Very Soft Orange, Slightly Desaturated Orange and Grayish Orange. Results in phenolics ranged from 796 to 15,949, 175 to 12,674 and 193 to 25,780 µgCE g-1 in total phenolics by Folin-Ciocalteu, total flavonoids by Aluminum Chloride and condensed tannins by Vanillin-HCl respectively. On the other hand, antioxidant capacity ranged from 1.20 to 93.83, 30.25 to 156.08 and 2.62 to 98.50 μmolTE g-1 in 2,2-diphenyl-1-picrylhydrazyl, 3-ethyl-benzothiazoline-6-sulfonic acid and Ferric Reducing Antioxidant Power respectively. Significant differences (p≤0.05 were observed in statistical analysis for both individual and group colour samples in chromatic, phenolics and antioxidant activity evaluations, showing ‘Rox Orange’ genotype and Grayish Orange colour group the highest levels.

  8. Chromatic instabilities in cesium-doped tungsten bronze nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Kenji, E-mail: kenji-adachi@ni.smm.co.jp; Ota, Yosuke; Tanaka, Hiroyuki; Okada, Mika; Oshimura, Nobumitsu; Tofuku, Atsushi [Ichikawa Research Laboratories, Sumitomo Metal Mining Co., Ltd., Ichikawa 272-8588 (Japan)

    2013-11-21

    Nanoparticles of alkali-doped tungsten bronzes are an excellent near-infrared shielding material, but exhibit slight chromatic instabilities typically upon applications of strong ultra-violet light or heating in humid environment, which acts detrimentally to long-life commercial applications. Origin of the chromatic instabilities in cesium-doped tungsten bronze has been investigated, and it has been found that the coloration and bleaching processes comprised electronic exchanges which accelerate or depress the polaron excitation and the localized surface plasmon resonance. Coloration on UV illumination is evidenced by electron diffraction as due to the formation of H{sub x}WO{sub 3}, which is considered to take place in the surface Cs-deficient WO{sub 3} region via the double charge injection mechanism. On the other hand, bleaching on heating in air and in humid environment is shown to accompany the extraction of Cs and electrons from Cs{sub 0.33}WO{sub 3} by X-ray photoelectron spectroscopy and X-ray diffraction analysis and is concluded to be an oxidation of Cs{sub 0.33}WO{sub 3} on the particle surface.

  9. The History of the Total Chromatic Number Conjecture

    CERN Document Server

    Shahmohamad, Hossein

    2011-01-01

    The total chromatic number conjecture which has appeared in a few hundred articles and in numerous books thus far is now one of the classic mathematical unsolved problems. It appears that many authors coincidentally have attributed it to Professor M. Behzad and/or to Professor V. G. Vizing. Eventually after four decades, Professor A. Soifer investigated the origin of this conjecture; published his findings in The Mathematical Coloring Book - 2009; and stated that, "In my opinion this unquestionably merits the joint credit to Vizing and Behzad." After checking all the arguments presented and the blames cited, I decided to investigate the controversy stated in this book on my own. My findings which are presented in this report specifically signify the following two points. - M. Behzad is the sole author of the Total Chromatic Number Conjecture. - The wrong referrals provided by numerous authors over the last forty four years, to indicate Vizing's authorship, must be brought to the attention of the authors and r...

  10. Chromatic instabilities in cesium-doped tungsten bronze nanoparticles

    Science.gov (United States)

    Adachi, Kenji; Ota, Yosuke; Tanaka, Hiroyuki; Okada, Mika; Oshimura, Nobumitsu; Tofuku, Atsushi

    2013-11-01

    Nanoparticles of alkali-doped tungsten bronzes are an excellent near-infrared shielding material, but exhibit slight chromatic instabilities typically upon applications of strong ultra-violet light or heating in humid environment, which acts detrimentally to long-life commercial applications. Origin of the chromatic instabilities in cesium-doped tungsten bronze has been investigated, and it has been found that the coloration and bleaching processes comprised electronic exchanges which accelerate or depress the polaron excitation and the localized surface plasmon resonance. Coloration on UV illumination is evidenced by electron diffraction as due to the formation of HxWO3, which is considered to take place in the surface Cs-deficient WO3 region via the double charge injection mechanism. On the other hand, bleaching on heating in air and in humid environment is shown to accompany the extraction of Cs and electrons from Cs0.33WO3 by X-ray photoelectron spectroscopy and X-ray diffraction analysis and is concluded to be an oxidation of Cs0.33WO3 on the particle surface.

  11. FTIR spectroscopic imaging and mapping with correcting lenses for studies of biological cells and tissues.

    Science.gov (United States)

    Kimber, James A; Foreman, Liberty; Turner, Benjamin; Rich, Peter; Kazarian, Sergei G

    2016-06-23

    lenses are also presented, which are necessary for correcting chromatic aberration and refraction in both the condenser and objective. The use of lenses is shown to be necessary for obtaining high-quality spectroscopic images of cells in transmission mode and proves the applicability of the pseudo hemisphere approach for this and other microfluidic systems.

  12. A local search algorithm based on chromatic classes for university course timetabling problem

    Directory of Open Access Journals (Sweden)

    Velin Kralev

    2016-12-01

    Full Text Available This paper presents a study for a local search algorithm based on chromatic classes for the university course timetabling problem. Several models and approaches to resolving the problem are discussed. The main idea of the approach is through a heuristic algorithm to specify the chromatic classes of a graph in which the events of the timetable correspond to the graph vertices and the set of the edges represents the possible conflicts between events. Then the chromatic classes should be sorted according to specific sort criteria (a total weight or a total count of events in each class, and finally the local search algorithm starts. The aim of the experiments is to determine the best criterion to sort chromatic classes. The results showed that the algorithm generates better solutions when the chromatic classes are sorted in a total weight criterion.

  13. Flow cytometric detection of aberrant chromosomes

    Energy Technology Data Exchange (ETDEWEB)

    Gray, J.W.; Lucas, J.; Yu, L.C.; Langlois, R.

    1983-05-11

    This report describes the quantification of chromosomal aberrations by flow cytometry. Both homogeneously and heterogeneously occurring chromosome aberrations were studied. Homogeneously occurring aberrations were noted in chromosomes isolated from human colon carcinoma (LoVo) cells, stained with Hoechst 33258 and chromomycin A3 and analyzed using dual beam flow cytometry. The resulting bivariate flow karyotype showed a homogeneously occurring marker chromosome of intermediate size. Heterogeneously occurring aberrations were quantified by slit-scan flow cytometry in chromosomes isolated from control and irradiated Chinese hamster cells and stained with propidium iodide. Heterogeneously occurring dicentric chromosomes were detected by their shapes (two centrometers). The frequencies of such chromosomes estimated by slit-scan flow cytometry correlated well with the frequencies determined by visual microscopy.

  14. Individual eye model based on wavefront aberration

    Science.gov (United States)

    Guo, Huanqing; Wang, Zhaoqi; Zhao, Qiuling; Quan, Wei; Wang, Yan

    2005-03-01

    Based on the widely used Gullstrand-Le Grand eye model, the individual human eye model has been established here, which has individual corneal data, anterior chamber depth and the eyeball depth. Furthermore, the foremost thing is that the wavefront aberration calculated from the individual eye model is equal to the eye's wavefront aberration measured with the Hartmann-shack wavefront sensor. There are four main steps to build the model. Firstly, the corneal topography instrument was used to measure the corneal surfaces and depth. And in order to input cornea into the optical model, high-order aspheric surface-Zernike Fringe Sag surface was chosen to fit the corneal surfaces. Secondly, the Hartmann-shack wavefront sensor, which can offer the Zernike polynomials to describe the wavefront aberration, was built to measure the wavefront aberration of the eye. Thirdly, the eye's axial lengths among every part were measured with A-ultrasonic technology. Then the data were input into the optical design software-ZEMAX and the crystalline lens's shapes were optimized with the aberration as the merit function. The individual eye model, which has the same wavefront aberrations with the real eye, is established.

  15. Assessment of Systematic Chromatic Errors that Impact Sub-1% Photometric Precision in Large-Area Sky Surveys

    CERN Document Server

    Li, T S; Marshall, J L; Tucker, D; Kessler, R; Annis, J; Bernstein, G M; Boada, S; Burke, D L; Finley, D A; James, D J; Kent, S; Lin, H; Marriner, J; Mondrik, N; Nagasawa, D; Rykoff, E S; Scolnic, D; Walker, A R; Wester, W; Abbott, T M C; Allam, S; Benoit-Lévy, A; Bertin, E; Brooks, D; Capozzi, D; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Diehl, H T; Doel, P; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Goldstein, D A; Gruen, D; Gruendl, R A; Gutierrez, G; Honscheid, K; Kuehn, K; Kuropatkin, N; Maia, M A G; Melchior28, P; Miller, C J; Miquel, R; Mohr, J J; Neilsen, E; Nichol, R C; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Sako, M; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Tarle, G; Thomas, D; Vikram, V

    2016-01-01

    Meeting the science goals for many current and future ground-based optical large-area sky surveys requires that the calibrated broadband photometry is stable in time and uniform over the sky to 1% precision or better. Past surveys have achieved photometric precision of 1-2% by calibrating the survey's stellar photometry with repeated measurements of a large number of stars observed in multiple epochs. The calibration techniques employed by these surveys only consider the relative frame-by-frame photometric zeropoint offset and the focal plane position-dependent illumination corrections, which are independent of the source color. However, variations in the wavelength dependence of the atmospheric transmission and the instrumental throughput induce source color-dependent systematic errors. These systematic errors must also be considered to achieve the most precise photometric measurements. In this paper, we examine such systematic chromatic errors using photometry from the Dark Energy Survey (DES) as an example...

  16. On the game chromatic number of sparse random graphs

    CERN Document Server

    Frieze, Alan; Lavrov, Mikhail

    2012-01-01

    Given a graph G and an integer k, two players take turns coloring the vertices of G one by one using k colors so that neighboring vertices get different colors. The first player wins iff at the end of the game all the vertices of $G$ are colored. The game chromatic number \\chi_g(G) is the minimum k for which the first player has a winning strategy. The paper \\cite{BFS} began the analysis of the asymptotic behavior of this parameter for a random graph G_{n,p}. This paper provides some further analysis for graphs with constant average degree i.e. np=O(1) and for random regular graphs.

  17. Chromatic perception of non-invasive lighting of cave paintings

    Science.gov (United States)

    Zoido, Jesús; Vazquez, Daniel; Álvarez, Antonio; Bernabeu, Eusebio; García, Ángel; Herraez, Juán A.; del Egido, Marian

    2009-08-01

    This work is intended to deal with the problems which arise when illuminanting Paleolithic cave paintings. We have carried out the spectral and colorimetric characterization of some paintings located in the Murcielagos (bats) cave (Zuheros, Córdoba, Spain). From this characterization, the chromatic changes produced under different lighting conditions are analysed. The damage function is also computed for the different illuminants used. From the results obtained, it is proposed an illuminant whose spectral distribution diminishes the damage by minimizing the absorption of radiation and optimises the color perception of the paintings in this cave. The procedure followed in this study can be applied to optimise the lighting systems used when illuminating any other art work

  18. Chromatic aftereffects associated with a night vision goggle simulation.

    Science.gov (United States)

    Moffitt, K; Rogers, S P; Cicinelli, J

    1988-02-01

    A visual perception experiment was conducted to determine the chromatic aftereffects of viewing a yellow-green field that simulated the display of current night vision goggles. Six females and two males served as subjects in a color-naming procedure. Subjects sequentially viewed an adaptation field, which was either yellow-green or white, and small colored targets presented on a CRT display. The time required to name the color of the targets was found to be dependent on the color of the adaptation field, the color of the target, and the interaction of these two variables. It was recommended that the effects of attenuation of the luminance of the night vision goggles be studied, and that color cockpit displays be redundantly coded whenever possible.

  19. The use of chromatic information for motion segmentation: differences between psychophysical and eye-movement measures.

    Science.gov (United States)

    Dobkins, Karen R; Sampath, Vanitha

    2008-01-01

    Previous psychophysical studies have shown that chromatic (red/green) information can be used as a segmentation cue for motion integration. We investigated the mechanisms mediating this phenomenon by comparing chromatic effects (and, for comparison, luminance effects) on motion integration between two measures: (i) directional eye movements with the notion that these responses are mediated mainly by low-level motion mechanisms, and (ii) psychophysical reports, with the notion that subjects' reports should employ higher-level (attention-based) mechanisms if available. To quantify chromatic (and luminance) effects on motion integration, coherent motion thresholds were obtained for two conditions, one in which the signal and noise dots were the same 'red' or 'green' chromaticity (or the same 'bright' or 'dark' luminance), referred to as homogeneous, and the other in which the signal and noise dots were of different chromaticities (or luminances), referred to as heterogeneous. 'Benefit ratios' (theta(HOM)/theta(HET)) were then computed, with values significantly greater than 1.0 indicating that chromatic (or luminance) information serves as a segmentation cue for motion integration. The results revealed a high and significant chromatic benefit ratio when the measure was based on psychophysical report, but not when it was based on an eye-movement measure. By contrast, luminance benefit ratios were roughly the same (and significant) for both measures. For comparison to adults, eye-movement data were also obtained from 3-month-old infants. Infants showed marginally significant benefit ratios in the luminance, but not in the chromatic, condition. In total, these results suggest that the use of chromatic information as a segmentation cue for motion integration relies on higher-level mechanisms, whereas luminance information works mainly through low-level motion mechanisms.

  20. Removal of Chromate Ions from Water by Anionicc CLAYS

    Science.gov (United States)

    Houri, B.; Legrouri, A.; Barroug, A.; Forano, C.; Besse, J.-P.

    1999-03-01

    The removal of chromate ions from aqueous solutions by [Mg-Al-Cl], [Zn-Al-Cl] and [Zn-Cr-Cl] anionic clays was investigated. The solids, prepared by coprecipitation at constant pH, were found to be pure upon characterisation by X-ray diffraction and Fourier-transform infrared spectroscopy. The interaction of the solid materials with CrO42- ions has been studied by UV-visible spectroscopy. The treatment of solutions containing 15 to 300 ppm of CrO42- was successful. The sorption capacities of the anionic clays for the CrO42- ions are close to 1 mmol/g. L'élimination des ions chromate de solutions aqueuses par les argiles anioniques [Mg-Al-Cl], [Zn-Al-Cl] et [Zn-Cr-Cl] a été étudiée. Les solides, préparés par coprécipitation à pH constant, ont été caractérisés par diffraction des rayons X et spectroscopie infrarouge à transformée de Fourier. L'interaction de ces matériaux avec les ions CrO42- a été suivie par spectroscopie UV-visible. Le traitement de solutions contenant de 15 à 300 ppm de CrO42- a donné de bons résultats. La capacité d'élimination de ces argiles anioniques pour les ions CrO42- est d'environ 1 mmol/g. .

  1. Repeated exposures to cobalt or chromate on the hands of patients with hand eczema and contact allergy to that metal

    DEFF Research Database (Denmark)

    Nielsen, N H; Kristiansen, J; Borg, L

    2000-01-01

    The present study aimed at evaluating the effects of daily repeated exposures to low cobalt or chromate concentrations on the hands of patients with hand eczema and cobalt or chromate allergy. For 2 weeks, the patients immersed a finger for 10 min daily into the appropriate metal salt solution...... in water. During the 1st week, this was a 10 or 50 mg/l cobalt concentration or a 10 mg/l chromate concentration, and, during the 2nd week, a 100 or 200 mg/l cobalt concentration or a 100 mg/l chromate concentration. This regimen elicited a flare of hand eczema only in the chromate-exposed chromate......-sensitive patients. During the exposure period, accumulation of cobalt or chromate in the nail was demonstrated. Standardization of chemical methods of quantification of skin exposure to allergens, combined with experimental exposure studies in patients with specific contact allergy, will increase the possibility...

  2. Measuring aberrations in the rat brain by coherence-gated wavefront sensing using a Linnik interferometer.

    Science.gov (United States)

    Wang, Jinyu; Léger, Jean-François; Binding, Jonas; Boccara, A Claude; Gigan, Sylvain; Bourdieu, Laurent

    2012-10-01

    Aberrations limit the resolution, signal intensity and achievable imaging depth in microscopy. Coherence-gated wavefront sensing (CGWS) allows the fast measurement of aberrations in scattering samples and therefore the implementation of adaptive corrections. However, CGWS has been demonstrated so far only in weakly scattering samples. We designed a new CGWS scheme based on a Linnik interferometer and a SLED light source, which is able to compensate dispersion automatically and can be implemented on any microscope. In the highly scattering rat brain tissue, where multiply scattered photons falling within the temporal gate of the CGWS can no longer be neglected, we have measured known defocus and spherical aberrations up to a depth of 400 µm.

  3. Simultaneous suppression of scattering and aberration for ultra-high resolution imaging deep within scattering media

    CERN Document Server

    Kang, Sungsam; Kang, Pilsung; Yang, Taeseok D; Ahn, Joonmo; Song, Kyungdeok; Choi, Wonshik

    2016-01-01

    Thick biological tissues give rise to not only the scattering of incoming light waves, but also aberrations of the remaining unscattered waves. Due to the inability of existing optical imaging methodologies to overcome both of these problems simultaneously, imaging depth at the sub- micron spatial resolution has remained extremely shallow. Here we present an experimental approach for identifying and eliminating aberrations even in the presence of strong multiple light scattering. For time-gated complex-field maps of reflected waves taken over various illumination channels, we identify two sets of aberration correction maps, one for the illumination path and one for the reflection path, that can preferentially accumulate the unscattered signal waves over the multiple-scattered waves. By performing closed-loop optimization for forward and phase- conjugation processes, we demonstrated a spatial resolution of 600 nm up to the unprecedented imaging depth of 7 scattering mean free paths.

  4. Computational genes: a tool for molecular diagnosis and therapy of aberrant mutational phenotype

    Directory of Open Access Journals (Sweden)

    Ignatova Zoya

    2007-09-01

    Full Text Available Abstract Background A finite state machine manipulating information-carrying DNA strands can be used to perform autonomous molecular-scale computations at the cellular level. Results We propose a new finite state machine able to detect and correct aberrant molecular phenotype given by mutated genetic transcripts. The aberrant mutations trigger a cascade reaction: specific molecular markers as input are released and induce a spontaneous self-assembly of a wild type protein or peptide, while the mutational disease phenotype is silenced. We experimentally demostrated in in vitro translation system that a viable protein can be autonomously assembled. Conclusion Our work demostrates the basic principles of computational genes and particularly, their potential to detect mutations, and as a response thereafter administer an output that suppresses the aberrant disease phenotype and/or restores the lost physiological function.

  5. Flat Supercontinuum Generated in a Single-Mode Optical Fibre with a New Chromatic Dispersion Profile

    Institute of Scientific and Technical Information of China (English)

    XU Yong-Zhao; REN Xiao-Min; ZHANG Xia; HUANG Yong-Qing; XU Wen-Cheng

    2005-01-01

    @@ A new chromatic dispersion profile of a single-mode opticalfibre is proposed for generating a supercontinuum with a flatly broadened spectrum. The chromatic dispersion D( λ, z) is a convex function of wavelengths and has no zero-dispersion wavelengths over the whole part of thefibre as D(λ, z) is negative. It is shown that the flat supercontinuum spectrum is obtained when the pump wavelength is set in the vicinity of the wavelength at which the peak chromatic dispersion is near zero and the strong residual pump component is eliminated.

  6. Explicit and probabilistic constructions of distance graphs with small clique numbers and large chromatic numbers

    Science.gov (United States)

    Kupavskii, A. B.

    2014-02-01

    We study distance graphs with exponentially large chromatic numbers and without k-cliques, that is, complete subgraphs of size k. Explicit constructions of such graphs use vectors in the integer lattice. For a large class of graphs we find a sharp threshold for containing a k-clique. This enables us to improve the lower bounds for the maximum of the chromatic numbers of such graphs. We give a new probabilistic approach to the construction of distance graphs without k-cliques, and this yields better lower bounds for the maximum of the chromatic numbers for large k.

  7. Characterization and genomic analysis of chromate resistant and reducing Bacillus cereus strain SJ1

    Directory of Open Access Journals (Sweden)

    He Minyan

    2010-08-01

    Full Text Available Abstract Background Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr(VI and Cr(III. Chromate [Cr(VI] is carcinogenic, mutational, and teratogenic due to its strong oxidizing nature. Biotransformation of Cr(VI to less-toxic Cr(III by chromate-resistant and reducing bacteria has offered an ecological and economical option for chromate detoxification and bioremediation. However, knowledge of the genetic determinants for chromate resistance and reduction has been limited so far. Our main aim was to investigate chromate resistance and reduction by Bacillus cereus SJ1, and to further study the underlying mechanisms at the molecular level using the obtained genome sequence. Results Bacillus cereus SJ1 isolated from chromium-contaminated wastewater of a metal electroplating factory displayed high Cr(VI resistance with a minimal inhibitory concentration (MIC of 30 mM when induced with Cr(VI. A complete bacterial reduction of 1 mM Cr(VI was achieved within 57 h. By genome sequence analysis, a putative chromate transport operon, chrIA1, and two additional chrA genes encoding putative chromate transporters that likely confer chromate resistance were identified. Furthermore, we also found an azoreductase gene azoR and four nitroreductase genes nitR possibly involved in chromate reduction. Using reverse transcription PCR (RT-PCR technology, it was shown that expression of adjacent genes chrA1 and chrI was induced in response to Cr(VI but expression of the other two chromate transporter genes chrA2 and chrA3 was constitutive. In contrast, chromate reduction was constitutive in both phenotypic and gene expression analyses. The presence of a resolvase gene upstream of chrIA1, an arsenic resistance operon and a gene encoding Tn7-like transposition proteins ABBCCCD downstream of chrIA1 in B. cereus SJ1 implied the possibility of recent horizontal gene transfer. Conclusion Our results indicate that expression of the chromate

  8. Beam-Based Error Identification and Correction Methods for Particle Accelerators

    CERN Document Server

    AUTHOR|(SzGeCERN)692826; Tomas, Rogelio; Nilsson, Thomas

    2014-06-10

    Modern particle accelerators have tight tolerances on the acceptable deviation from their desired machine parameters. The control of the parameters is of crucial importance for safe machine operation and performance. This thesis focuses on beam-based methods and algorithms to identify and correct errors in particle accelerators. The optics measurements and corrections of the Large Hadron Collider (LHC), which resulted in an unprecedented low β-beat for a hadron collider is described. The transverse coupling is another parameter which is of importance to control. Improvement in the reconstruction of the coupling from turn-by-turn data has resulted in a significant decrease of the measurement uncertainty. An automatic coupling correction method, which is based on the injected beam oscillations, has been successfully used in normal operation of the LHC. Furthermore, a new method to measure and correct chromatic coupling that was applied to the LHC, is described. It resulted in a decrease of the chromatic coupli...

  9. A Label-Free and Chemical-Selective Microendoscope to Enhance Prostate Cancer Surgical Outcomes

    Science.gov (United States)

    2013-10-01

    different glass components in the micro- objective system would lead to catastrophic chromatic aberration in the CARS microendoscope probe. Precise...indicates that the chromatic aberration is well corrected and image performance is diffraction limited. The image performance of the micro-objective

  10. Computation of astigmatic and trefoil figure errors and misalignments for two-mirror telescopes using nodal-aberration theory.

    Science.gov (United States)

    Ju, Guohao; Yan, Changxiang; Gu, Zhiyuan; Ma, Hongcai

    2016-05-01

    In active optics systems, one concern is how to quantitatively separate the effects of astigmatic and trefoil figure errors and misalignments that couple together in determining the total aberration fields when wavefront measurements are available at only a few field points. In this paper, we first quantitatively describe the impact of mount-induced trefoil deformation on the net aberration fields by proposing a modified theoretical formulation for the field-dependent aberration behavior of freeform surfaces based on the framework of nodal aberration theory. This formulation explicitly expresses the quantitative relationships between the magnitude of freeform surfaces and the induced aberration components where the freeform surfaces can be located away from the aperture stop and decentered from the optical axis. On this basis, and in combination with the mathematical presentation of nodal aberration theory for the effects of misalignments, we present the analytic expressions for the aberration fields of two-mirror telescopes in the presence of astigmatic primary mirror figure errors, mount-induced trefoil deformations on both mirrors, and misalignments. We quantitatively separate these effects using the analytical expressions with wavefront measurements at a few field points and pointing errors. Valuable insights are provided on how to separate these coupled effects in the computation process. Monte Carlo simulations are conducted to demonstrate the correctness and accuracy of the analytic method presented in this paper.

  11. A single mechanism for both luminance and chromatic grating vernier tasks: evidence from temporal summation.

    Science.gov (United States)

    Sun, Hao; Lee, Barry B

    2004-01-01

    Vernier thresholds are determined by luminance rather than chromatic contrast when both are present in vernier targets. The role of luminance and chromatic mechanisms in vernier performance under equiluminant conditions remains uncertain. Temporal summation functions for vernier thresholds with luminance and red-green equiluminant gratings were compared to those for detection thresholds with similar stimuli. Vernier thresholds showed similar temporal summation for luminance and chromatic gratings, which is consistent with a single mechanism underlying vernier performance in the two conditions. However, detection thresholds showed a shorter temporal summation duration for luminance gratings than for chromatic gratings, which suggests that two different mechanisms underlie detection thresholds. Analysis of physiological data supports the hypothesis that the frequency-doubled response of ganglion cells in the magnocellular pathway can provide accurate spatiotemporal information for vernier performance at equiluminance.

  12. Achromatic-chromatic colorimetric sensors for on-off type detection of analytes.

    Science.gov (United States)

    Heo, Jun Hyuk; Cho, Hui Hun; Lee, Jin Woong; Lee, Jung Heon

    2014-12-21

    We report the development of achromatic colorimetric sensors; sensors changing their colors from achromatic black to other chromatic colors. An achromatic colorimetric sensor was prepared by mixing a general colorimetric indicator, whose color changes between chromatic colors, and a complementary colored dye with no reaction to the targeted analyte. As the color of an achromatic colorimetric sensor changes from black to a chromatic color, the color change could be much easily recognized than general colorimetric sensors with naked eyes. More importantly, the achromatic colorimetric sensors enable on-off type recognition of the presence of analytes, which have not been achieved from most colorimetric sensors. In addition, the color changes from some achromatic colorimetric sensors (achromatic Eriochrome Black T and achromatic Benedict's solution) could be recognized with naked eyes at much lower concentration ranges than normal chromatic colorimetric sensors. These results provide new opportunities in the use of colorimetric sensors for diverse applications, such as harsh industrial, environmental, and biological detection.

  13. Measurement of Stratospheric Chromatic Scintillation with the AMON-RA Balloonborne Spectrometer.

    Science.gov (United States)

    Renard, J B; Dalaudier, F; Hauchecorne, A; Robert, C; Lemaire, T; Pirre, M; Bertaux, J L

    2001-08-20

    The balloonborne instrument AMON (which is a French acronym for Absorption par les Minoritaires Ozone et NO(x)) has been modified to record chromatic scintillation during stellar occultation by the Earth's atmosphere. A 14-channel spectrophotometer with a sampling rate of 10 Hz was added, and the modified instrument, AMON-RA, performed successful measurements of the setting star Alnilam during the third European Stratospheric Experiment on Ozone (THESEO) project. Unambiguous records of the chromatic scintillation were obtained, to our knowledge for the first time from above the atmosphere, and some of its basic properties are reported. The properties of atmospheric structures that are responsible for this chromatic scintillation were found to be consistent with those of previous monochromatic measurements performed from space. A maximum chromatic delay of 2.5 s was observed for widely different wavelengths.

  14. Higher order aberrations in amblyopic children and their role in refractory amblyopia

    Directory of Open Access Journals (Sweden)

    Arnaldo Dias-Santos

    2014-12-01

    Full Text Available Objective: Some studies have hypothesized that an unfavourable higher order aberrometric profile could act as an amblyogenic mechanism and may be responsible for some amblyopic cases that are refractory to conventional treatment or cases of “idiopathic” amblyopia. This study compared the aberrometric profile in amblyopic children to that of children with normal visual development and compared the aberrometric profile in corrected amblyopic eyes and refractory amblyopic eyes with that of healthy eyes. Methods: Cross-sectional study with three groups of children – the CA group (22 eyes of 11 children with unilateral corrected amblyopia, the RA group (24 eyes of 13 children with unilateral refractory amblyopia and the C group (28 eyes of 14 children with normal visual development. Higher order aberrations were evaluated using an OPD-Scan III (NIDEK. Comparisons of the aberrometric profile were made between these groups as well as between the amblyopic and healthy eyes within the CA and RA groups. Results: Higher order aberrations with greater impact in visual quality were not significantly higher in the CA and RA groups when compared with the C group. Moreover, there were no statistically significant differences in the higher order aberrometric profile between the amblyopic and healthy eyes within the CA and RA groups. Conclusions: Contrary to lower order aberrations (e.g., myopia, hyperopia, primary astigmatism, higher order aberrations do not seem to be involved in the etiopathogenesis of amblyopia. Therefore, these are likely not the cause of most cases of refractory amblyopia.

  15. Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

    Science.gov (United States)

    Rachon, M.; Liebert, K.; Siemion, A.; Bomba, J.; Sobczyk, A.; Knap, W.; Coquillat, D.; Suszek, J.; Sypek, M.

    2017-03-01

    Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.

  16. Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

    Science.gov (United States)

    Rachon, M.; Liebert, K.; Siemion, A.; Bomba, J.; Sobczyk, A.; Knap, W.; Coquillat, D.; Suszek, J.; Sypek, M.

    2016-11-01

    Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.

  17. Relativistic stellar aberration for the Space Interferometry Mission

    CERN Document Server

    Turyshev, S G

    2002-01-01

    This paper analyses the relativistic stellar aberration requirements for the Space Interferometry Mission (SIM). We address the issue of general relativistic deflection of light by the massive self-gravitating bodies. Specifically, we present estimates for corresponding deflection angles due to the monopole components of the gravitational fields of a large number of celestial bodies in the solar system. We study the possibility of deriving an additional navigational constraints from the need to correct for the gravitational bending of light that is traversing the solar system. It turns out that positions of the outer planets presently may not have a sufficient accuracy for the precision astrometry. However, SIM may significantly improve those simply as a by-product of its astrometric program. We also consider influence of the higher gravitational multipoles, notably the quadrupole and the octupole ones, on the gravitational bending of light. Thus, one will have to model and account for their influence while o...

  18. Understanding the tune, coupling, and chromaticity dependence of the LHC on Landau octupole powering.

    CERN Document Server

    Maclean, E H; Persson, T; Tomas, R; Wenninger, J

    2013-01-01

    During the 2012 LHC run several observations were made of shifts to tune, coupling and chromaticity which were correlated with changes in the powering of Landau octupoles. Understanding the chromaticity dependence is of particular importance given its influence on instabilities. This note briefly summarizes the observations and describes our understanding to-date of the relationship between Q, Q′, |C−| and the Landau octupole powering.

  19. CHROMATICITY COORDINATES EVALUATION OF TRIANGLE VERTICES GAMUT FOR DISPLAYS WITH MAXIMUM AREA OF COLOR REPRODUCTION

    Directory of Open Access Journals (Sweden)

    I. O. Zharinov

    2016-09-01

    Full Text Available We consider the problem of calculating chromaticity coordinates estimates of triangle vertices gamut for displays with maximum area of color reproduction. Initial data for the evaluation are tabulated data on the shape of the spectral locus interpolated by Bezier splines. Research results are chromaticity coordinates of the triangle vertices gamut maximum area specified on the color chart according to the standards of the International Commission on Illumination.

  20. Joint IQ Skew and Chromatic Dispersion Estimation for Coherent Optical Communication Receivers

    DEFF Research Database (Denmark)

    Medeiros Diniz, Júlio César; Porto da Silva, Edson; Piels, Molly

    2016-01-01

    A low-complexity scanning method for joint estimation of receiver IQ skew and chromatic dispersion is proposed. This method shows less than 1 ps skew error for a 1200-km 32-GBd DP-16QAM optical transmission experiment.......A low-complexity scanning method for joint estimation of receiver IQ skew and chromatic dispersion is proposed. This method shows less than 1 ps skew error for a 1200-km 32-GBd DP-16QAM optical transmission experiment....

  1. EVALUATION OF DISTRIBUTION HISTOGRAMS FOR INCREMENT OF CHROMATICITY COORDINATES IN DISPLAY TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    I. O. Zharinov

    2016-05-01

    Full Text Available We consider evaluation problem of chromaticity coordinates increment for an image displayed by indicating means (liquid crystal panels and etc.. Display device profile set by the weight matrix for components of primary colors serves as basic data for quantitative calculation. Research results have the form of mathematical expressions allowing calculation of increment values of chromaticity coordinates of the image displayed on indicating means and histograms of increment distribution.

  2. Protective effect of ginger against toxicity induced by chromate in rats.

    Science.gov (United States)

    Krim, Meriem; Messaadia, Amira; Maidi, Imen; Aouacheri, Ouassila; Saka, Saad

    2013-01-01

    The evaluation of the effect of ginger on the modulation of toxic effects induced by chromate is the objective of our study. 50 male rats Albinos Wistar were divided to five groups as follow: group I (T) is served as control, received a mineral water by gavage (per os); group II (G) received an experimental diet with 2% of ginger; group III (Cr) received an oral dose of potassium dichromate (15 mg/kg) and normal diet; group IV (CrG): received an oral dose of potassium dichromate (15 mg/kg) and an experimental diet containing 2% ginger; and group V (Cr(+)G) received an oral dose of potassium dichromate (25 mg/kg) and an experimental diet with 2% of ginger. The results of this study indicate that the chromate provoked a haematoxic effect (anemia), nephrotoxic, hepatotoxic, and also a perturbation in lipids profile. In addition, chromate has a pro-oxidant effect, which was indicated by decrease of reduced glutathione (GSH) levels in different tissues. However, the administration of ginger revealed a reduction of the intensity of oxidative stress induced by the chromate resulting in the decrease of the majority of the previous parameters concentrations. In conclusion we demonstrated that ginger has potent antioxidants activity, revealed by the amelioration of chromate's toxic effects. We can say that ginger has a protective effect towards damages induced by the chromate.

  3. Nanocomposites of Magnetite and Layered Double Hydroxide for Recyclable Chromate Removal

    Directory of Open Access Journals (Sweden)

    Gyeong-Hyeon Gwak

    2016-01-01

    Full Text Available Nanocomposites containing magnetic iron oxide (magnetite nanoparticles and layered double hydroxide (LDH nanosheets were prepared by two different methods, exfoliation-reassembly and coprecipitation, for aqueous chromate adsorbent. According to X-ray diffraction, scanning electron microscopy, and atomic force microscopy, both nanocomposites were determined to develop different nanostructures; LDH nanosheets well covered magnetite nanoparticles with house-of-cards-like structure in exfoliation-reassembly method, while coprecipitation resulted in LDH particle formation along with magnetite nanoparticles. Zeta-potential measurement also revealed that the magnetite surface was effectively covered by LDH moiety in exfoliation-reassembly compared with coprecipitation. Time, pH, concentration dependent chromate adsorption tests, and magnetic separation experiments exhibited that both nanocomposites effectively adsorb and easily collect chromate. However, exfoliation-reassembly nanocomposite was determined to be slightly effective in chromate removal by ~10%. Chromate adsorbed nanocomposites could be regenerated by treating with bicarbonate and the regenerated nanocomposites preserved ~80% of chromate adsorption efficacy after three times of recycling.

  4. A new class of chromatic filters for color image processing. Theory and applications.

    Science.gov (United States)

    Lucchese, Luca; Mitra, Sanjit K

    2004-04-01

    This paper advances a new framework for chromatic filtering of color images. The chromatic content of a color image is encoded in the CIE u'v' chromaticity coordinates whereas the achromatic content is encoded as CIE Y tristimulus value. Within the u'v' chromaticity diagram, colors are added according to the well-known center of gravity law of additive color mixtures, which is generalized here into a nonlinear filtering scheme for processing the two chromatic signals u' and v'. The achromatic channel Y can be processed with traditional filtering schemes, either linear or nonlinear, depending on the specific task at hand. The most interesting characteristics of the new filtering scheme are: 1) the elimination of color smearing effects along edges between bright and dark areas; 2) the possibility of processing chromatic components in a noniterative fashion through linear convolution operations; and 3) the consequent amenability to computationally efficient implementations with fast Fourier transform. The paper includes several examples with both synthetic and real images where the performance of the new filtering method is compared with that of other color image processing algorithms.

  5. Assessing the construct validity of aberrant salience.

    Science.gov (United States)

    Schmidt, Kristin; Roiser, Jonathan P

    2009-01-01

    We sought to validate the psychometric properties of a recently developed paradigm that aims to measure salience attribution processes proposed to contribute to positive psychotic symptoms, the Salience Attribution Test (SAT). The "aberrant salience" measure from the SAT showed good face validity in previous results, with elevated scores both in high-schizotypy individuals, and in patients with schizophrenia suffering from delusions. Exploring the construct validity of salience attribution variables derived from the SAT is important, since other factors, including latent inhibition/learned irrelevance (LIrr), attention, probabilistic reward learning, sensitivity to probability, general cognitive ability and working memory could influence these measures. Fifty healthy participants completed schizotypy scales, the SAT, a LIrr task, and a number of other cognitive tasks tapping into potentially confounding processes. Behavioural measures of interest from each task were entered into a principal components analysis, which yielded a five-factor structure accounting for approximately 75% of the variance in behaviour. Implicit aberrant salience was found to load onto its own factor, which was associated with elevated "Introvertive Anhedonia" schizotypy, replicating our previous finding. LIrr loaded onto a separate factor, which also included implicit adaptive salience, but was not associated with schizotypy. Explicit adaptive and aberrant salience, along with a measure of probabilistic learning, loaded onto a further factor, though this also did not correlate with schizotypy. These results suggest that the measures of LIrr and implicit adaptive salience might be based on similar underlying processes, which are dissociable both from implicit aberrant salience and explicit measures of salience.

  6. [Aberrant pancreas with a double intestinal location].

    Science.gov (United States)

    Yenon, K; Lethurgie, C; Bokobza, B

    2005-01-01

    The authors report one exceptional case of aberrant pancreas with a double intestinal location (jejunum and Meckel's diverticulum) in a thirty-year-old patient. Digestive haemorrhage and the abdominal colic were the revealing clinical signs. The enteroscopy guided by the enteroscanner, was the indicated complementary investigation for the preoperative diagnosis. The research of other locations during the operation should be systematic.

  7. Functional Analysis and Treatment of Aberrant Behavior.

    Science.gov (United States)

    Mace, F. Charles; And Others

    1991-01-01

    This article reviews general classes of variables which help to maintain aberrant behavior including attention seeking, sensory and perceptual consequences, and access to materials or activities. Suggestions for a methodology providing a comprehensive functional analysis are offered which include descriptive analysis, hypothesis forming,…

  8. Prenatal hydronephrosis caused by aberrant renal vessels

    DEFF Research Database (Denmark)

    Lenz, K; Thorup, Jørgen Mogens; Rabol, A;

    1996-01-01

    With routine use of obstetric ultrasonography, fetal low-grade hydronephrosis is commonly detected, but may resolve spontaneously after birth. Two cases are presented to illustrate that in some cases such findings can express intermittent hydronephrosis caused by aberrant renal vessels. Renal...

  9. Pigment chromatic adaptation in Cyclotella caspia Grunow (Bacillariophyta

    Directory of Open Access Journals (Sweden)

    Donato Seiji Abe

    1991-01-01

    Full Text Available The diatom Cyclotella caspia Grunow, isolated from surface waters of the Ubatuba region (São Paulo State, Brazil was submitted to different light spectral distributions for examination of its adaptative response. Growth rate and the photosynthetic pigments chlorophyll a, chlorophyll c, carotenoids and phaeopigments were measured under white, blue and red light of the same intensity (8 and 20 µE.cm-2.s-1. Growth rate increased under blue light while red light increased chl a concentration. The relative proportion of chl a and carotenoids did not change, demonstrating the absence of complementary chromatic adaptation.A diatomácea Cyclotella caspia Grunow, isolada de águas superficiais da região de Ubatuba (Estado de São Paulo, Brasil, foi submetida a diferentes intervalos espectrais de luz com a finalidade de se examinar sua resposta adaptativa. Foram medidos a taxa de crescimento e os pigmentos fotossintéticos clorofila a, clorofila c, carotenóides e feopigmentos, sob luz branca, azul e vermelha de mesmas intensidades (8 e 20 µE.cm-2.s-1. A taxa de crescimento aumentou sob luz azul, sendo que a concentração de clorofila a aumentar sob luz vermelha. A proporção relativa de clα e carotenóides não variou, demonstrando a ausência de adapatação cromática complementar.

  10. The dependence of luminous efficiency on chromatic adaptation.

    Science.gov (United States)

    Stockman, Andrew; Jägle, Herbert; Pirzer, Markus; Sharpe, Lindsay T

    2008-12-15

    We investigated the dependence of luminous efficiency on background chromaticity by measuring 25-Hz heterochromatic flicker photometry (HFP) matches in six genotyped male observers on 21 different 1000-photopic-troland adapting fields: 14 spectral ones ranging from 430 to 670 nm and 7 bichromatic mixtures of 478 and 577 nm that varied in luminance ratio. Each function was analyzed in terms of the best-fitting linear combination of the long- (L) and middle- (M) wavelength sensitive cone fundamentals of A. Stockman and L. T. Sharpe (2000). Taking into account the adapting effects of both the backgrounds and the targets, we found that luminous efficiency between 603 and 535 nm could be predicted by a simple model in which the relative L- and M-cone weights are inversely proportional to the mean cone excitations produced in each cone type multiplied by a single factor, which was roughly independent of background wavelength (and may reflect relative L:M cone numerosity). On backgrounds shorter than 535 nm and longer than 603 nm, the M-cone contribution to luminous efficiency falls short of the proportionality prediction but most likely for different reasons in the two spectral regions.

  11. Chromatic visualization of reflectivity variance within hybridized directional OCT images

    Science.gov (United States)

    Makhijani, Vikram S.; Roorda, Austin; Bayabo, Jan Kristine; Tong, Kevin K.; Rivera-Carpio, Carlos A.; Lujan, Brandon J.

    2013-03-01

    This study presents a new method of visualizing hybridized images of retinal spectral domain optical coherence tomography (SDOCT) data comprised of varied directional reflectivity. Due to the varying reflectivity of certain retinal structures relative to angle of incident light, SDOCT images obtained with differing entry positions result in nonequivalent images of corresponding cellular and extracellular structures, especially within layers containing photoreceptor components. Harnessing this property, cross-sectional pathologic and non-pathologic macular images were obtained from multiple pupil entry positions using commercially-available OCT systems, and custom segmentation, alignment, and hybridization algorithms were developed to chromatically visualize the composite variance of reflectivity effects. In these images, strong relative reflectivity from any given direction visualizes as relative intensity of its corresponding color channel. Evident in non-pathologic images was marked enhancement of Henle's fiber layer (HFL) visualization and varying reflectivity patterns of the inner limiting membrane (ILM) and photoreceptor inner/outer segment junctions (IS/OS). Pathologic images displayed similar and additional patterns. Such visualization may allow a more intuitive understanding of structural and physiologic processes in retinal pathologies.

  12. Deformable Membrane Mirror for Wavefront Correction (Short Communication

    Directory of Open Access Journals (Sweden)

    Amita Gupta

    2009-11-01

    Full Text Available Deformable or adaptive mirrors are used in modern adaptive optics systems for direct correction of the aberrations in the light wavefront. Conventional deformable mirrors used for this purpose are expensive electromechanical devices. Deformable membrane mirror fabricated using microelectromechanical systems (MEMS technology is a low cost, compact adaptive optical element for correction of the lower-order optical aberrations such as defocus and astigmatism. In this paper, important aspects of device design and simulation, fabrication techniques, and test results are discussed.Defence Science Journal, 2009, 59(6, pp.590-594, DOI:http://dx.doi.org/10.14429/dsj.59.1563

  13. Differentiated Effects of Sensory Activities as Abolishing Operations via Non-Contingent Reinforcement on Academic and Aberrant Behavior

    Science.gov (United States)

    Mancil, G. Richmond; Haydon, Todd; Boman, Marty

    2016-01-01

    The purpose of the study was to evaluate the effectiveness of sensory activities used as antecedent interventions on the percentage correct on academic tasks and rate of aberrant behavior in three elementary aged children with Autism Spectrum Disorders (ASD). Study activities were conducted in an after school program for children with ASD where…

  14. Determination of chromated copper arsenate (CCA) in treated wood of Eucalyptus

    Energy Technology Data Exchange (ETDEWEB)

    Parreira, Paulo S., E-mail: parreira@uel.b [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica. Lab.de Fisica Nuclear Aplicada; Vendrametto, Guilherme R.; Cunha, Magda E.T., E-mail: grvendrametto@gmail.co [Universidade Norte do Parana, Arapongas, PR (Brazil). Centro de Ciencias Humanas, da Saude, Exatas e Tecnologicas-A

    2009-07-01

    This work deals with the possible application of a portable energy dispersive handmade system (PXRF-LFNA-02) for the determination of Chromium, Copper and Arsenic in the preservative solution used to protect commercial wood of Eucalyptus, which are employed as wood fence, posts, contention fences, railroad sleepers, etc. It was prepared five body-of-proof made of eucalyptus alburnum with different concentrations for each element varying from 0.0061 to 0.0180 (g/g) for CrO{sub 3}, 0.0024 to 0.0070 (g/g) for CuO and 0.0044 to 0.0129 (g/g) for As{sub 2}O{sub 5}. Four of them were used for calibration curves and one used as reference sample. It was used a commercial CCA (Chromated Copper Arsenate ) solution to prepare the samples. The results show a good linear regression between concentrations and X-rays intensities, after applied the multiple linear regression methodology for interelemental corrections. The values obtained with this methodology were 3.01(kg/m{sup 3}), 1.18 (kg/m{sup 3}) e 2.21 (kg/m{sup 3}) for CrO{sub 3}, CuO and As{sub 2}O{sub 5}, respectively, while the nominal values are 2.90 (kg/m{sup 3}) for CrO{sub 3}, 1.13 (kg/m{sup 3}) for CuO and 2.07 (kg/m{sup 3}) for As{sub 2}O{sub 5}. The ED-XRF (Energy Dispersive X-Rays Fluorescence) is a well established technique with high-speed of analytical procedure and its portable configuration allowing a multielemental, simultaneous and non destructive analyses besides in situ application. (author)

  15. TREATMENT TESTS FOR EX SITU REMOVAL OF CHROMATE & NITRATE & URANIUM (VI) FROM HANFORD (100-HR-3) GROUNDWATER FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    BECK MA; DUNCAN JB

    1994-01-03

    This report describes batch and ion exchange column laboratory scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}{sup -}) and uranium (present as uranium [VI]) from contaminated Hanford site groundwaters. The technologies investigated include: chemical precipitation or coprecipitation to remove chromate and uranium; and anion exchange to remove chromate, uranium and nitrate. The technologies investigated were specified in the 100-HR-3 Groundwater Treatability Test Plan. The method suggested for future study is anion exchange.

  16. ANION EXCHANGE CAPACITY OF CHROMATE ON MODIFIED ZEOLITE CLINOPTILOLITE WITH HDTMA-Br AND ITS REGENERATION

    Directory of Open Access Journals (Sweden)

    Widajanti Wibowo

    2011-04-01

    Full Text Available Zeolite Clinoptilolite from Lampung, located in South of Sumatra, had been modified with surfactanthexadecyltrimethylammonium bromide (HDTMA-Br as chromate anion exchanger. Surfactant modified zeolite (SMZClinoptilolite in particle size range of 1.5 - 2.0 mm, which contained 196.7 mmol HDTMA-Br/kg zeolite, was used foranion exchange of chromate at neutral pH. This experiment was conducted in a glass column filled with 5 gram SMZ.The breakthrough chromate exchange capacity was found 1.262 mg/g SMZ, while the total capacity was found 2.107mg/g SMZ. The regeneration of SMZ saturated with chromate was conducted using a mixed solutions of 0.28 MNa2CO3 and 0.5 M NaOH, compared with using a solution of 0.01 M Na2S2O4. The desorption of chromate achieved92% with the mixed solutions of Na2CO3 and NaOH and 90% with the Na2S2O4 solution. The regenerated SMZ withNa2CO3-NaOH solutions was prior washed with HCl solution to remove the carbonate from SMZ, before being used forchromate sorption again. Its breakthrough capacity was reduced to 1.074 mg/g SMZ, and to 0.724 mg/g SMZ whenregenerated with Na2S2O4 solution. These results indicated that regeneration of SMZ affected its exchange capacity foranion chromate. However, it is still could be acceptable, when Na2CO3/NaOH solutions were used for the regenerationof SMZ saturated with anion chromate.

  17. Final-focus optics for the LHeC electron beam line

    CERN Document Server

    Abelleira, J; Tomas, R; Zimmermann, F

    2012-01-01

    One of the options considered for the ECFA-CERNNuPECC design study for a Large Hadron electron Collider (LHeC) based on the LHC is adding a recirculating energy-recovery linac tangential to the LHC. First designs of the electron Final Focus System have shown the need to correct the chromatic aberrations. Two designs using different approaches for the chromaticity correction are compared, namely, the local chromaticity correction and the traditional approach using dedicated sections.

  18. Assessing the construct validity of aberrant salience

    Directory of Open Access Journals (Sweden)

    Kristin Schmidt

    2009-12-01

    Full Text Available We sought to validate the psychometric properties of a recently developed paradigm that aims to measure salience attribution processes proposed to contribute to positive psychotic symptoms, the Salience Attribution Test (SAT. The “aberrant salience” measure from the SAT showed good face validity in previous results, with elevated scores both in high-schizotypy individuals, and in patients with schizophrenia suffering from delusions. Exploring the construct validity of salience attribution variables derived from the SAT is important, since other factors, including latent inhibition/learned irrelevance, attention, probabilistic reward learning, sensitivity to probability, general cognitive ability and working memory could influence these measures. Fifty healthy participants completed schizotypy scales, the SAT, a learned irrelevance task, and a number of other cognitive tasks tapping into potentially confounding processes. Behavioural measures of interest from each task were entered into a principal components analysis, which yielded a five-factor structure accounting for ~75% percent of the variance in behaviour. Implicit aberrant salience was found to load onto its own factor, which was associated with elevated “Introvertive Anhedonia” schizotypy, replicating our previous finding. Learned irrelevance loaded onto a separate factor, which also included implicit adaptive salience, but was not associated with schizotypy. Explicit adaptive and aberrant salience, along with a measure of probabilistic learning, loaded onto a further factor, though this also did not correlate with schizotypy. These results suggest that the measures of learned irrelevance and implicit adaptive salience might be based on similar underlying processes, which are dissociable both from implicit aberrant salience and explicit measures of salience.

  19. Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes

    Directory of Open Access Journals (Sweden)

    Inmaculada Cabezos

    2015-01-01

    Full Text Available Background: Some diseases that affect the visual system may show loss of chromatic-achromatic sensitivity before obvious physical signs appear in the usual examination of the eye′s posterior segment. A perimetric study has been conducted with four typical patients with glaucoma and diabetes, at different stages of the disease. Materials and Methods: In addition to the standard white-on-white (standard automated perimetry [SAP], a test battery has been used to study patient′s contrast sensitivity, using stimuli with different chromatic, spatial, and temporal content (multichannel perimetry. The choice of stimuli tries to maximize the response of different visual mechanisms: Achromatic (parvocellular and magnocellular origin; chromatic red-green (parvocellular origin; and chromatic blue-yellow (koniocellular origin. Results: The results seem to indicate losses in the achromatic-parvocellular perimetry and both chromatic perimetry tests, undetected by conventional SAP. Conclusions: Our results illustrate that our patients without visible retinal alterations show signs of suspicion in multichannel perimetry.

  20. CLASSIFICATION OF COMPLETE 5-PARTITE GRAPHS AND CHROMATICITY OF 5-PARTITE GRAPHSWITH 5n VERTICES

    Institute of Scientific and Technical Information of China (English)

    ZhaoHaixing; LiuRuying; ZhangShenggui

    2004-01-01

    For a graph G,P(G,λ)denotes the chromatic polynomial of G. Two graphs G and H are said to be chromatically equivalent,denoted by G-H,if P(G,λ)=p(H,λ). Let[G]= {H|H-G}. If [G]={G},then G is said to be chromatically unique. For a complete 5-partite graph G with 5n vertices, define θ(G)=(a(G,6)-2n+1-2n-1+5)/2n-2,where a(G,6) denotes the number of 6-independent partitions of G. In this paper, the authors show that θ(G)≥0 and determine all graphs with θ(G)= 0, 1, 2, 5/2, 7/2, 4, 17/4. By using these results the chromaticity of 5-partite graphs of the form G-S with θ(G)=0,1,2,5/2,7/2,4,17/4 is investigated,where S is a set of edges of G. Many new chromatically unique 5-partite graphs are obtained.

  1. Variable aberration generator using a high-order even aspheric singlet for testing optical surfaces

    Science.gov (United States)

    Lu, Jinfeng; Chen, Shanyong; Xue, Shuai

    2016-10-01

    Traditional null optics is generally designed for a particular optical surface. It must be redesigned when the test surface is changed no matter the null optic is reflective, transmitted or a CGH. Development of advanced optical machining and testing based on deterministic figuring and null test makes it possible to apply high-order aspheres. This paper presents a plano-concave singlet to realize variable aberration correction for testing different surfaces. The concave surface is an even asphere with high-order terms. By changing the axial distances among the transmission sphere, the null singlet and the test surface, variable aberrations are generated to meet the aberration balance requirement for various surfaces. The residual aberrations are confirmed within the vertical dynamic range of measurement of the interferometer. It enables flexible testing of optical surfaces without dedicated null optics. The optical design verifies that the aspheric singlet can be used to test conic surfaces with different conic constant and radius of curvature ranging from ellipsoid, paraboloid to hyperboloid and an even asphere.

  2. Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation

    Institute of Scientific and Technical Information of China (English)

    HOU Jing; XIAO Rui

    2006-01-01

    We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier (MOPA) configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved.It can be used not only to obtain high power fibre laser array but also in laser space communication.

  3. Misalignment-induced nodal aberration fields in two-mirror astronomical telescopes.

    Science.gov (United States)

    Schmid, Tobias; Thompson, Kevin P; Rolland, Jannick P

    2010-06-01

    We present the effects of misalignments on the field dependence of the third-order aberration fields of traditional, two-mirror astronomical telescopes in the context of nodal aberration theory, which we believe is the most general and extensible framework for describing and improving on-station performance. While many of the advantages of nodal aberration theory, compared to other, often power series expansion-based descriptions of misalignment effects on aberrations, become particularly important when analyzing telescopes with more than two mirrors, or in the presence of figure errors; this paper aims to provide and demonstrate the fundamental concepts needed to fully describe the state of correction of misaligned two-mirror telescopes. Importantly, it is shown that the assumption that perfect performance on axis ensures a fully aligned telescope is false, and we demonstrate that if Ritchey-Chrétien telescopes are aligned for zero coma on axis as the sole criterion, formidable misalignments will likely remain, leading to image quality degradation, particularly beyond midfield caused by astigmatism with binodal field dependence (i.e., astigmatism goes to zero at two points in the field).

  4. [Familial, structural aberration of the Y chromosome with fertility disorders].

    Science.gov (United States)

    Gall, H; Schmid, M; Schmidtke, J; Schempp, W; Weber, L

    1985-11-01

    Cytogenetic studies on a patient with Klinefelter's syndrome revealed an inherited, structural aberration of the Y-chromosome which has not been described before. The aberrant Y-chromosome was characterized by eight different banding methods. The value of individual staining techniques in studies on Y-heterochromatin aberrations is emphasized. Analysis of the cytogenetic studies (banding methods, restriction endonuclease of DNA, and measurement of the length of the Y-chromosome) permits an interpretation to be made on how the aberrant Y-chromosome originated. The functions of the Y-chromosome are discussed. The decrease in fertility (cryptozoospermia) in the two brothers with the same aberrant Y-chromosome was striking.

  5. The Effect of Cross-Linking Treatment on Conus Curvature and Higher Order Corneal Aberrations in Keratoconus

    Directory of Open Access Journals (Sweden)

    Sücattin İlker Kocamış

    2014-05-01

    Full Text Available Objectives: To study the effect of corneal collagen cross-linking on conus curvature and corneal aberrations in keratoconus. Materials and Methods: The medical records of thirty-seven eyes of 32 progressive keratoconus patients (17 male, 15 female, mean age: 22.13±4.64 years who had undergone corneal cross-linking were evaluated retrospectively. The change in refractive errors, visual acuity on Snellen charts, average keratometry, conus curvature, and corneal aberrations calculated at 6.00 mm pupil size throughout the follow-up time were compared with paired t-test. The correlation of the change in best-corrected visual acuity and in uncorrected visual acuity with the change of the parameters which had statistically significant difference at 18 months was studied with Pearson’s correlation analysis. Results: The best-corrected visual acuity, uncorrected visual acuity, spherical and cylindrical error, average keratometry, conus curvature, vertical coma, total corneal aberrations, total higher order aberrations had statistically significant difference at 18 postoperative months (p=0.001. Spherical aberration (p=0.95 and horizontal coma (p=0.78 did not show statistically significant difference at the end of follow-up. The change in uncorrected visual acuity correlated with change in conus curvature (r=-0.420, p=0.01 and change in cylindrical refraction (r=0.453, p=0.005 at 18 months. The change in best-corrected visual acuity correlated with change in total corneal aberrations (r=-0.490, p=0.002, vertical coma (r=0.408, p=0.01, average keratometry (r=-0.386, p=0.02, conus curvature (r=-0.381, p=0.02, and total higher order aberrations (r=-0.326, p=0.05 at 18 months. Conclusion: Corneal collagen cross-linking treatment applied to progressive keratoconus cases induces significant decrease in conus curvature, in total corneal aberrations, and in higher order aberrations, especially in vertical coma, and leads to a prominent visual acuity increase

  6. Radiotherapeutical chromosomal aberrations in laryngeal cancer patients

    Directory of Open Access Journals (Sweden)

    Stošić-Divjak Svetlana L.

    2009-01-01

    Full Text Available Introduction. The authors present the results of cytogenetic analysis of 21 patients with laryngeal carcinomas diagnosed and treated in the period 1995-2000 at the Institute of Otorhinolaryngology and Maxillofacial Surgery, Clinical Center of Serbia and Clinical Center of Novi Sad. Material and methods. The patients were specially monitored and the material was analyzed at the Institute of Human Genetics of the School of Medicine in Belgrade as well as in the Laboratory for Radiological Protection of the Institute of Occupational and Radiological Health 'Dr Dragomir Karajovic' in Belgrade. Results. The incidence of chromosomal aberrations and incidence of exchange of material between sister chromatids were observed in the preparation of the metaphasic lymphocyte chromosomes of the peripheral blood obtained in the culture. Structural aberrations were found on the chromosomes in the form of breakups, rings, translocations and dicentrics as early as after a single exposure of patients to tumor radiation dose of 2 Gy in the field sized 5x7. Out of the total number of 35 cultivated blood samples obtained from 13 patients, 21 were successfully cultivated and they were proved to contain chromosomal aberrations. Some of the peripheral blood samples failed to show cell growth in vitro due to the lethal cell damages in vivo. Discussion.. We have consluded that the number of structural aberrations cannot be used as a biological measure of the absorbed ionizing radiation dose. The presence of aberrations per se is indicative of the mutagenic effect of the ionizing radiation, which was also confirmed in our series on the original model by cultivation of the peripheral blood lymphocytes in the culture of the cells of the volunteer donors upon in vitro radiation. Using the method of bromdeoxyuridylreductase, the increased incidence of SCE as a mutagenic effect was registered. Conclusion. It has been concluded that the increase of absorbed radiation dose in

  7. Nodal aberration theory for wild-filed asymmetric optical systems

    Science.gov (United States)

    Chen, Yang; Cheng, Xuemin; Hao, Qun

    2016-10-01

    Nodal Aberration Theory (NAT) was used to calculate the zero field position in Full Field Display (FFD) for the given aberration term. Aiming at wide-filed non-rotational symmetric decentered optical systems, we have presented the nodal geography behavior of the family of third-order and fifth-order aberrations. Meanwhile, we have calculated the wavefront aberration expressions when one optical element in the system is tilted, which was not at the entrance pupil. By using a three-piece-cellphone lens example in optical design software CodeV, the nodal geography is testified under several situations; and the wavefront aberrations are calculated when the optical element is tilted. The properties of the nodal aberrations are analyzed by using Fringe Zernike coefficients, which are directly related with the wavefront aberration terms and usually obtained by real ray trace and wavefront surface fitting.

  8. Limits on Foreground Subtraction from Chromatic Beam Effects in Global Redshifted 21 cm Measurements

    CERN Document Server

    Mozdzen, Thomas J; Monsalve, Raul A; Rogers, Alan E E

    2015-01-01

    Foreground subtraction in global redshifted 21 cm measurements is limited by frequency-dependent (chromatic) structure in antenna beam patterns. Chromatic beams couple angular structures in Galactic foreground emission to spectral structures that may not be removed by smooth functional forms. We report results for simulations based on two dipole antennas used by the Experiment to Detect the Global EoR Signature (EDGES). The residual levels in simulated foreground-subtracted spectra are found to differ substantially between the two antennas, suggesting that antenna design must be carefully considered. Residuals are also highly dependent on the right ascension and declination of the antenna pointing, with RMS values differing by as much as a factor of 20 across pointings. For EDGES and other ground-based experiments with zenith pointing antennas, right ascension and declination correspond directly to the local sidereal time and the latitude of the deployment site, hence chromatic beam effects should be taken in...

  9. An XPS study of the adsorption of chromate on goethite ( α-FeOOH)

    Science.gov (United States)

    Abdel-Samad, Hesham; Watson, Philip R.

    1997-03-01

    The adsorption behavior of inorganic oxyanions on soil minerals is an important factor in the transport of subsurface environmental pollutants. We have studied the adsorption of chromate (CrO 42-) from aqueous solution on the surface of the mineral goethite ( α-FeOOH) as a function of pH and adsorbate concentration in 0.05 M NaNO 3 solution. Results obtained from the dried surface by X-ray photoelectron spectroscopy (XPS) are in good agreement with data from spectrophotometric analysis of chromate remaining in the supernatant liquid. Chromate adsorption increases with decreasing pH of the solution and eventually reaches a maximum at pH 6.5. The chromium XPS signal indicates that initially a small amount of chromium adsorbs in the +3 oxidation state via a redox reaction, but that the large majority of chromium remains in the +6 oxidation state.

  10. Versatile chromatic dispersion measurement of a single mode fiber using spectral white light interferometry.

    Science.gov (United States)

    Lee, Ji Yong; Kim, Dug Young

    2006-11-27

    We present a versatile and accurate chromatic dispersion measurement method for single mode optical fibers over a wide spectral range (200 nm) using a spectral domain white light interferometer. This technique is based on spectral interferometry with a Mach-Zehnder interferometer setup and a broad band light source. It takes less than a second to obtain a spectral interferogram for a few tens of centimeter length fiber sample. We have demonstrated that the relative group velocity, the chromatic dispersion and the dispersion slope of a sample fiber can be obtained very accurately regardless of the zero-dispersion wavelength (ZDW) of a sample after frequency dependent optical phase was directly retrieved from a spectral interferogram. The measured results with our proposed method were compared with those obtained with a conventional time-domain dispersion measurement method. A good agreement between those results indicates that our proposed method can measure the chromatic dispersion of a short length optical fiber with very high accuracy.

  11. Structure determination and functional analysis of a chromate reductase from Gluconacetobacter hansenii.

    Directory of Open Access Journals (Sweden)

    Hongjun Jin

    Full Text Available Environmental protection through biological mechanisms that aid in the reductive immobilization of toxic metals (e.g., chromate and uranyl has been identified to involve specific NADH-dependent flavoproteins that promote cell viability. To understand the enzyme mechanisms responsible for metal reduction, the enzyme kinetics of a putative chromate reductase from Gluconacetobacter hansenii (Gh-ChrR was measured and the crystal structure of the protein determined at 2.25 Å resolution. Gh-ChrR catalyzes the NADH-dependent reduction of chromate, ferricyanide, and uranyl anions under aerobic conditions. Kinetic measurements indicate that NADH acts as a substrate inhibitor; catalysis requires chromate binding prior to NADH association. The crystal structure of Gh-ChrR shows the protein is a homotetramer with one bound flavin mononucleotide (FMN per subunit. A bound anion is visualized proximal to the FMN at the interface between adjacent subunits within a cationic pocket, which is positioned at an optimal distance for hydride transfer. Site-directed substitutions of residues proposed to involve in both NADH and metal anion binding (N85A or R101A result in 90-95% reductions in enzyme efficiencies for NADH-dependent chromate reduction. In comparison site-directed substitution of a residue (S118A participating in the coordination of FMN in the active site results in only modest (50% reductions in catalytic efficiencies, consistent with the presence of a multitude of side chains that position the FMN in the active site. The proposed proximity relationships between metal anion binding site and enzyme cofactors is discussed in terms of rational design principles for the use of enzymes in chromate and uranyl bioremediation.

  12. Ground Based Synoptic Instrumentation for Solar Observations (Postprint)

    Science.gov (United States)

    2012-03-05

    None are corrected for chromatic aberration . The system overall is diffraction limited for all wavelengths in the tunable range. The magnifier lens...simultaneously corrects for chromatic focus effects and maintains a constant solar diameter throughout the year. The magnifier lens is interchangeable

  13. UHF Signal Processing and Pattern Recognition of Partial Discharge in Gas-Insulated Switchgear Using Chromatic Methodology

    Science.gov (United States)

    Wang, Xiaohua; Li, Xi; Rong, Mingzhe; Xie, Dingli; Ding, Dan; Wang, Zhixiang

    2017-01-01

    The ultra-high frequency (UHF) method is widely used in insulation condition assessment. However, UHF signal processing algorithms are complicated and the size of the result is large, which hinders extracting features and recognizing partial discharge (PD) patterns. This article investigated the chromatic methodology that is novel in PD detection. The principle of chromatic methodologies in color science are introduced. The chromatic processing represents UHF signals sparsely. The UHF signals obtained from PD experiments were processed using chromatic methodology and characterized by three parameters in chromatic space (H, L, and S representing dominant wavelength, signal strength, and saturation, respectively). The features of the UHF signals were studied hierarchically. The results showed that the chromatic parameters were consistent with conventional frequency domain parameters. The global chromatic parameters can be used to distinguish UHF signals acquired by different sensors, and they reveal the propagation properties of the UHF signal in the L-shaped gas-insulated switchgear (GIS). Finally, typical PD defect patterns had been recognized by using novel chromatic parameters in an actual GIS tank and good performance of recognition was achieved. PMID:28106806

  14. Rare earth and silane as chromate replacers for corrosion protection on galvanized steel

    Institute of Scientific and Technical Information of China (English)

    PENG Tianlan; MAN Ruilin

    2009-01-01

    The present work aimed at using rare earth lanthanum salt and trimethoxy(viny)silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate. The corrosion resistance was assessed by electrochemical impedance spectroscopy (EIS) and neutral salt spray tests (NSS). Scanning electron microscopy (SEM) was used to characterize the sample surfaces. The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests. The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion. The coating formation mechanism was also discussed.

  15. On Chromatic no. of 3K1-free graphs and R(3, k)

    OpenAIRE

    Dhurandhar, Medha S.

    2012-01-01

    Here we prove that if G has independence no. 2 and clique size omega with omega less than or equal to 11, then (1) chromatic no. is less than or equal to (omega2+12omega-13)/8, if omega is odd, and (2) chromatic no. is less than or equal to (omega2+10omega)/8, if omega is even. We further conjecture that the results are true in general for all omega. We also conjecture that (A) if omega is odd and R(3, omega) is even, then R(3, omega) = (omega2+8omega-9)/4, (B) if omega and R(3, omega) are bo...

  16. Betatron Tune Spread Generation and Differential Chromaticity Control by Octupole at Tevatron

    CERN Document Server

    Ivanov, Petr M; Annala, Jerry; Lebedev, Valeri

    2005-01-01

    Application of octupoles for Landau damping of the unstable head-tail modes requires careful consideration at their combination into separate families to insure maximum effectiveness and avoid degradation of the dynamic aperture due to the non-linear magnetic fields. Existing octupolar magnets around the machine have been arranged into four functional families with individual power supplies. Two of these families generate betatron tune spreads in the vertical and horizontal planes whereas the other two control the differential chromaticity between the proton and antiproton helices. The calculated effect on tunes and chromaticity is compared with direct measurements. Analytical formulas for betatron tune spectral density functions are presented.

  17. Varying chromaticity: A damping mechanism for the transverse head-tail instability

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, W.; Wurtele, J.S. [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States); Sessler, A.M.; Wurtele, J.S. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    1997-10-01

    A detailed analytical and numerical study of the suppression of the transverse head-tail instability by modulating the chromaticity over a synchrotron period is presented. We find that a threshold can be developed, and it can be increased to a value larger than the strong head-tail instability threshold. The stability criterion derived agrees very well with the simulations. The underlying physical mechanisms of the damping scheme are rotation of the head-tail phase such that the instability does not occur, and Landau damping due to the incoherent betatron tune spread generated by the varying chromaticity. {copyright} {ital 1997} {ital The American Physical Society}

  18. Coded-subcarrier-aided chromatic dispersion monitoring scheme for flexible optical OFDM networks.

    Science.gov (United States)

    Tse, Kam-Hon; Chan, Chun-Kit

    2014-08-11

    A simple coded-subcarrier aided scheme is proposed to perform chromatic dispersion monitoring in flexible optical OFDM networks. A pair of coded label subcarriers is added to both edges of the optical OFDM signal spectrum at the edge transmitter node. Upon reception at any intermediate or the receiver node, chromatic dispersion estimation is performed, via simple direct detection, followed by electronic correlation procedures with the designated code sequences. The feasibility and the performance of the proposed scheme have been experimentally characterized. It provides a cost-effective monitoring solution for the optical OFDM signals across intermediate nodes in flexible OFDM networks.

  19. New chromaticity compensation approach and dynamic aperture increase in the SSRF storage ring

    Institute of Scientific and Technical Information of China (English)

    TIAN Shun-Qiang; HOU Jie; CHEN Guang-Ling; LIU Gui-Min

    2008-01-01

    Strong chromatic sextupoles used to compensate natural chromaticities in the third generation light source storage ring usually reduce dynamic aperture drastically.Many optimization methods can be used to find solutions that provide large dynamic apertures.This paper discusses a new optimization approach of sextupole strengths with step-by-step procedure,which is applied in the SSRF storage ring,and a better solution is obtained.Investigating driving terms generated by the sextupoles in every step can analyze their convergences and guide the weight setting among different terms in object function of the single resonance approach based on the perturbation theory.

  20. Wavefront aberrations of x-ray dynamical diffraction beams.

    Science.gov (United States)

    Liao, Keliang; Hong, Youli; Sheng, Weifan

    2014-10-01

    The effects of dynamical diffraction in x-ray diffractive optics with large numerical aperture render the wavefront aberrations difficult to describe using the aberration polynomials, yet knowledge of them plays an important role in a vast variety of scientific problems ranging from optical testing to adaptive optics. Although the diffraction theory of optical aberrations was established decades ago, its application in the area of x-ray dynamical diffraction theory (DDT) is still lacking. Here, we conduct a theoretical study on the aberration properties of x-ray dynamical diffraction beams. By treating the modulus of the complex envelope as the amplitude weight function in the orthogonalization procedure, we generalize the nonrecursive matrix method for the determination of orthonormal aberration polynomials, wherein Zernike DDT and Legendre DDT polynomials are proposed. As an example, we investigate the aberration evolution inside a tilted multilayer Laue lens. The corresponding Legendre DDT polynomials are obtained numerically, which represent balanced aberrations yielding minimum variance of the classical aberrations of an anamorphic optical system. The balancing of classical aberrations and their standard deviations are discussed. We also present the Strehl ratio of the primary and secondary balanced aberrations.

  1. Chromosomal aberrations in ISS crew members

    Science.gov (United States)

    Johannes, Christian; Goedecke, Wolfgang; Antonopoulos, Alexandra

    2012-07-01

    High energy radiation is a major risk factor in manned space missions. Astronauts and cosmonauts are exposed to ionising radiations of cosmic and solar origin, while on the Earth's surface people are well protected by the atmosphere and a deflecting magnetic field. There are now data available describing the dose and the quality of ionising radiation on-board of the International Space Station (ISS). Nonetheless, the effect of increased radiation dose on mutation rates of ISS crew members are hard to predict. Therefore, direct measurements of mutation rates are required in order to better estimate the radiation risk for longer duration missions. The analysis of chromosomal aberrations in peripheral blood lymphocytes is a well established method to measure radiation-induced mutations. We present data of chromosome aberration analyses from lymphocyte metaphase spreads of ISS crew members participating in short term (10-14 days) or long term (around 6 months) missions. From each subject we received two blood samples. The first sample was drawn about 10 days before launch and a second one within 3 days after return from flight. From lymphocyte cultures metaphase plates were prepared on glass slides. Giemsa stained and in situ hybridised metaphases were scored for chromosome changes in pre-flight and post-flight blood samples and the mutation rates were compared. Results obtained in chromosomal studies on long-term flight crew members showed pronounced inter-individual differences in the response to elevated radiation levels. Overall slight but significant elevations of typical radiation induced aberrations, i.e., dicentric chromosomes and reciprocal translocations have been observed. Our data indicate no elevation of mutation rates due to short term stays on-board the ISS.

  2. Aberration-free volumetric high-speed imaging of in vivo retina

    Science.gov (United States)

    Hillmann, Dierck; Spahr, Hendrik; Hain, Carola; Sudkamp, Helge; Franke, Gesa; Pfäffle, Clara; Winter, Christian; Hüttmann, Gereon

    2016-10-01

    Certain topics in research and advancements in medical diagnostics may benefit from improved temporal and spatial resolution during non-invasive optical imaging of living tissue. However, so far no imaging technique can generate entirely diffraction-limited tomographic volumes with a single data acquisition, if the target moves or changes rapidly, such as the human retina. Additionally, the presence of aberrations may represent further difficulties. We show that a simple interferometric setup-based on parallelized optical coherence tomography-acquires volumetric data with 10 billion voxels per second, exceeding previous imaging speeds by an order of magnitude. This allows us to computationally obtain and correct defocus and aberrations resulting in entirely diffraction-limited volumes. As demonstration, we imaged living human retina with clearly visible nerve fiber layer, small capillary networks, and photoreceptor cells. Furthermore, the technique can also obtain phase-sensitive volumes of other scattering structures at unprecedented acquisition speeds.

  3. Aberration-free volumetric high-speed imaging of in vivo retina

    CERN Document Server

    Hillmann, Dierck; Hain, Carola; Sudkamp, Helge; Franke, Gesa; Pfäffle, Clara; Winter, Christian; Hüttmann, Gereon

    2016-01-01

    Research and medicine rely on non-invasive optical techniques to image living tissue with high resolution in space and time. But so far a single data acquisition could not provide entirely diffraction-limited tomographic volumes of rapidly moving or changing targets, which additionally becomes increasingly difficult in the presence of aberrations, e.g., when imaging retina in vivo. We show, that a simple interferometric setup based on parallelized optical coherence tomography acquires volumetric data with 10 billion voxels per second, exceeding previous imaging speeds by an order of magnitude. This allows us to computationally obtain and correct defocus and aberrations resulting in entirely diffraction-limited volumes. As demonstration, we imaged living human retina with clearly visible nerve fiber layer, small capillary networks, and photoreceptor cells, but the technique is also applicable to obtain phase-sensitive volumes of other scattering structures at unprecedented acquisition speeds.

  4. Aberration-free two-thin-lens systems based on negative-index materials

    Institute of Scientific and Technical Information of China (English)

    Lin Zhi-Li; Ding Jie-Chen; Zhang Pu

    2008-01-01

    Since the complete correction of all five monochromatic Seidel aberrations for a singlet lens with random shape or a two-thin-lens system is unprocurable merely by using the conventional positive-index materials both in theory and practice, this paper proposes that when one or both of the two lenses is/are made from negative-index materials, an imaging system composed of a pair of spherical thin lenses is possible to form a real image, in air, free from all five monochromatic Seidel aberrations. The calculated numerical solutions to the structural parameters of such lens systems possessing superior performance are provided and examples of them are illustrated for the given combinations of the two lenses' refractive indices, including an ultimately-remote imaging system.

  5. The oxygen isotope composition of dissolved chromate: a new tool for determining sources of chromium contamination in groundwater

    Science.gov (United States)

    Bullen, T.; Widory, D.

    2009-05-01

    Hexavalent chromium (Cr(VI)) is a widespread carcinogen in groundwater, derived from both anthropogenic and natural sources. A large range of chromium isotope composition has been demonstrated for dissolved Cr(VI) in groundwater, resulting from the large isotope fractionation accompanying reduction of Cr(VI) to trivalent chromium (Cr(III)). As a result, the isotopic composition of chromium in dissolved chromate is beginning to prove useful for determining the sources of chromium in contaminated groundwater, but considered alone can likewise be non-diagnostic due to overlapping compositional ranges of potential anthropogenic and natural sources. Based on the strong Cr-O bond in the chromate molecule implied by the large chromium isotope fractionation accompanying Cr(VI) reduction, we have proposed that oxygen will remain closely linked to chromium in the chromate molecule and thus can be used to better constrain chromate sources through a Cr-O "multi-tracer" approach. In a series of laboratory experiments using isotopically "enriched" water and "normal" chromate, we have demonstrated that there is insignificant isotopic exchange between oxygen in chromate and water for residence times as long as one year, and thus chromate will retain the oxygen isotope composition of its source during extended transport in groundwater. We have likewise demonstrated that sufficient chromate for oxygen isotope analysis can be successfully isolated from a chemically complex groundwater sample through a series of precipitation, ion exchange and heating procedures. Although our current approach of measuring 100 micromolar samples of chromate using TCEA- gas mass spectrometry is straightforward and robust, we are also developing a negative-ion thermal ionization mass spectrometry technique in order to greatly reduce the sample size requirement. We are currently applying this novel technique at an electric power facility in California and a metal plating facility in France in order to

  6. Aberrations in Fresnel Lenses and Mirrors

    Science.gov (United States)

    Gregory, Don

    1999-01-01

    The NASA/MSFC Shooting Star program revealed a number of technical problems that must be solved before solar thermal propulsion can become a reality. The fundamental problem of interest here is the collection of solar energy. This is the first step in the propulsion process and indeed the most important. Everything else depends on the efficiency and focusing ability of the collection lens or mirror. An initial model of Fresnel lens behavior using a wave optics approach has been completed and the results were encouraging enough to warrant an experimental investigation. This experimental investigation confirmed some of the effects predicted and produced invaluable photographic evidence of coherence based diffraction and aberration.

  7. Aberration measurement from specific photolithographic images: a different approach.

    Science.gov (United States)

    Nomura, H; Tawarayama, K; Kohno, T

    2000-03-01

    Techniques for measurement of higher-order aberrations of a projection optical system in photolithographic exposure tools have been established. Even-type and odd-type aberrations are independently obtained from printed grating patterns on a wafer by three-beam interference under highly coherent illumination. Even-type aberrations, i.e., spherical aberration and astigmatism, are derived from the best focus positions of vertical, horizontal, and oblique grating patterns by an optical microscope. Odd-type aberrations, i.e., coma and three-foil, are obtained by detection of relative shifts of a fine grating pattern to a large pattern by an overlay inspection tool. Quantitative diagnosis of lens aberrations with a krypton fluoride (KrF) excimer laser scanner is demonstrated.

  8. Effects of iron stress on chromatic adaptation by natural phytoplankton communities in the Southern Ocean

    NARCIS (Netherlands)

    van Leeuwe, M.A.; Timmermans, K.R.; Witte, H.J.; Kraay, G.W.; Veldhuis, M.J.W.; de Baar, H.J.W.

    1998-01-01

    Effects of iron stress on chromatic adaptation were studied in natural phytoplankton communities collected in the Pacific region of the Southern Ocean. Iron enrichment experiments (48 to 72 h) were performed, incubating plankton communities under white, green and blue light respectively, with and wi

  9. SIMULTANEOUS DTERMINATION OF CHROMATE AND AROMATIC HYDROCARBONS IN ENVIRONMENTAL SAMPLES BY CAPILLARY ELECTROPHORESIS

    Science.gov (United States)

    An analytical method was developed to determine simultaneously, the inorganic anion CrO2-4, and organic aromatic compounds including benzoate, 2-Cl-benzoate, phenol, m-cresol and o-/p-cresol by capillary electrophoresis (CE). Chromate and the aromatics were separated in a relativ...

  10. Perception of Chromatic cues during host location by the pupal parasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae)

    NARCIS (Netherlands)

    Fischer, S.; Samietz, J.; Wäckers, F.L.; Dorn, S.

    2004-01-01

    Chromatic and achromatic plant cues are expected to be particularly important for parasitoids of endophytic pupal hosts, because these stages do not feed and therefore avoid volatile emission caused by plant tissue damage. Endophytic feeding can cause discoloration or desiccation, leading to changes

  11. Measurement of chromatic dispersion of microstructured polymer fibers by white-light spectral interferometry

    DEFF Research Database (Denmark)

    Hlubina, Petr; Ciprian, Dalibor; Frosz, Michael Henoch;

    2009-01-01

    of the method by measuring the wavelength dependence of the differential group refractive index of a pure silica fiber. We apply a five-term power series fit to the measured data and confirm by its differentiation that the chromatic dispersion of pure silica glass agrees well with theory. Second, we measure...

  12. A "Green" Passivation of Zinc containing surfaces as an alternative to chromate

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Møller, Per

    1996-01-01

    With view to a replacement for chromate passivation, Molyphos was developed under the Danish Materials Programme I (MUP I). In the Danish Materials Programme II(MUP II), the further development of Molyphos a molybdate phosphate conversion coating has been undertaken by application of a sealer...

  13. Delay differential models in multimode laser dynamics: taking chromatic dispersion into account

    Science.gov (United States)

    Vladimirov, A. G.; Huyet, G.; Pimenov, A.

    2016-04-01

    A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes.

  14. Segmentation of color images by chromaticity features using self-organizing maps

    Directory of Open Access Journals (Sweden)

    Farid García-Lamont

    2016-08-01

    Full Text Available Usually, the segmentation of color images is performed using cluster-based methods and the RGB space to represent the colors. The drawback with these methods is the a priori knowledge of the number of groups, or colors, in the image; besides, the RGB space issensitive to the intensity of the colors. Humans can identify different sections within a scene by the chromaticity of its colors of, as this is the feature humans employ to tell them apart. In this paper, we propose to emulate the human perception of color by training a self-organizing map (SOM with samples of chromaticity of different colors. The image to process is mapped to the HSV space because in this space the chromaticity is decoupled from the intensity, while in the RGB space this is not possible. Our proposal does not require knowing a priori the number of colors within a scene, and non-uniform illumination does not significantly affect the image segmentation. We present experimental results using some images from the Berkeley segmentation database by employing SOMs with different sizes, which are segmented successfully using only chromaticity features.

  15. Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers

    DEFF Research Database (Denmark)

    Borkowski, Robert; Johannisson, Pontus; Wymeersch, Henk;

    2014-01-01

    We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) ...

  16. On the chromatic number of pentagon-free graphs of large minimum degree

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2007-01-01

    We prove that, for each fixed real number c > 0, the pentagon-free graphs of minimum degree at least cn (where n is the number of vertices) have bounded chromatic number. This problem was raised by Erdős and Simonovits in 1973. A similar result holds for any other fixed odd cycle, except the tria...

  17. Comparative study of visual acuity and aberrations after intralase femtosecond LASIK: small corneal flap versus big corneal flap

    Institute of Scientific and Technical Information of China (English)

    Ya-Li; Zhang; Lei; Liu; Chang-Xia; Cui; Ming; Hu; Zhao-Na; Li; Li-Jun; Cao; Xiu-Hua; Jing; Guo-Ying; Mu

    2014-01-01

    AIM:To study the effects of different flap sizes on visual acuity, refractive outcomes, and aberrations after femtosecond laser for laser keratomileusis (LASIK). ·METHODS: In each of the forty patients enrolled, 1 eye was randomly assigned to receive treatment with a 8.1mm diameter corneal flap, defined as the small flap, while the other eye was treated with a 8.6mm diameter corneal flap, defined as the big flap. Refractive errors, visual acuity, and higher -order aberrations were compared between the two groups at week 1, month 1 and 3 postoperatively. · RESULTS: The postoperative refractive errors and visual acuity all conformed to the intended goal. Postoperative higher -order aberrations were increased, especially in spherical aberration (Z12) and vertical coma (Z7). There were no statistically significant differences between the two groups in terms of postoperative refractive errors, visual acuity, root mean square of total HOAs (HO -RMS), trefoil 30° (Z6), vertical coma (Z7), horizontal coma (Z8), trefoil 0° (Z9), and spherical aberration (Z12) at any point during the postoperative follow-up. ·CONCLUSION: Both the small and big flaps are safe and effective procedures to correct myopia, provided the exposure stroma meets the excimer laser ablations. The personalized size corneal flap is feasible, as we can design the size of corneal flap based on the principle that the corneal flap diameter should be equal to or greater than the sum of the maximum ablation diameter and apparatus error.

  18. Comparative analysis of clastogen-induced chromosome aberrations observed with light microscopy and by means of atomic force microscopy.

    Science.gov (United States)

    Koleva, Vanya Petrova; Dragoeva, Asya Pencheva; Andreeva, Andreana Ivanova; Burova, Marina Todorova; Georgiev, Sevdalin; Enchev, Dobromir Dimitrov

    2013-04-30

    Different types of chromosome aberration were observed in mouse bone-marrow cells after treatment with 4-bromo-N,N-diethyl-5,5-dimethyl-2,5-dihydro-1,2-oxaphosphol-2-amine 2-oxide (Br-oxaphosphole, Br-oxph) in a previous study. The aim of the present study is to perform a comparative analysis of these chromosomal damages observed with light microscopy (LM) and by means of atomic force microscopy (AFM). The kinds of aberrations scored by LM were substantially corrected by images at the ultrastructural level. The AFM analysis excluded 29.0% of gaps and 33.3% of fusion-type aberrations. On the other hand, AFM revealed the presence of aberrations that were not visible under the LM. This indicates that only AFM images would provide precise information about the real nature of chromosomal damages. The results of our study revealed that the 'real gaps' represented about 50% of all the gaps visible under LM. Excluded 'false gaps' were detected via AFM as breaks or decondensed chromosome regions. These results would support the statement that gaps must be included when testing genotoxicity. The ultrastructural analysis also confirmed the validity of using LM in the mouse bone-marrow chromosome aberration test, as a tool for detecting genotoxicity of chemicals in routine studies. When there is a need for precise evaluation of chromosome damage, only AFM images can provide information on specific genotoxic effects.

  19. Cellular origin of prognostic chromosomal aberrations in AML patients

    DEFF Research Database (Denmark)

    Mora-Jensen, H.; Jendholm, J.; Rapin, N.;

    2015-01-01

    karyotype have demonstrated the presence of prognostic driver aberrations (that is, NPM1, FLT3-ITD and FLT3-TKD) in committed HPCs but not in multipotent HSCs. However, the HSC populations lacking the prognostic driver aberrations contained preleukemic clones harboring a series of recurrent molecular...... aberrations that were present in the fully transformed committed HPCs together with the prognostic driver aberration. Adding to this vast heterogeneity and complexity of AML genomes and their clonal evolution, a recent study of a murine AML model demonstrated that t(9;11) AML originating from HSCs responded...

  20. 100-D Area In Situ Redox Treatability Test for Chromate-Contaminated Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mark D.; Vermeul, Vincent R.; Szecsody, James E.; Fruchter, Jonathan S.

    2000-10-12

    A treatability test was conducted for the In Situ Redox Manipulation (ISRM) technology at the 100 D Area of the U. S. Department of Energy's Hanford Site. The target contaminant was dissolved chromate in groundwater. The ISRM technology creates a permeable subsurface treatment zone to reduce mobile chromate in groundwater to an insoluble form. The ISRM permeable treatment zone is created by reducing ferric iron to ferrous iron within the aquifer sediments, which is accomplished by injecting aqueous sodium dithionite into the aquifer and then withdrawing the reaction products. The goal of the treatability test was to create a linear ISRM barrier by injecting sodium dithionite into five wells. Well installation and site characterization activities began in spring 1997; the first dithionite injection took place in September 1997. The results of this first injection were monitored through the spring of 1998. The remaining four dithionite injections were carried out in May through July of 1998.These five injections created a reduced zone in the Hanford unconfined aquifer approximately 150 feet in length (perpendicular to groundwater flow) and 50 feet wide. The reduced zone extended over the thickness of the unconfined zone. Analysis of post-emplacement groundwater samples showed concentrations of chromate, in the reduced zone decreased from approximately 1.0 mg/L before the tests to below analytical detection limits (<0.007 mg/L). Chromate concentrations also declined in downgradient monitoring wells to as low as 0.020 mg/L. These data, in addition to results from pre-test reducible iron characterization, indicate the barrier should be effective for 20 to 25 years. The 100-D Area ISRM barrier is being expanded to a length of up to 2,300 ft to capture a larger portion of the chromate plume.

  1. Assessing chromate availability in tropical ultramafic soils using isotopic exchange kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, Jeremie; Quantin, Cecile [Univ. Paris Sud CNRS, Orsay (France); Echevarria, Guillaume [ENSAIA-INPL-INRA, Vandoeuvre-les-Nancy (France); Becquer, Thierry [IRD - Univ. Paris VI and XII, Montpellier (France)

    2009-10-15

    Background, aim, and scope The presence of labile chromate in the soils is an environmental problem because of its high toxicity. The isotopic exchange kinetics (IEK) methods have been shown to be a useful tool to measure the phytoavailability of major (P, K) and trace elements (Cd, Zn, Ni, Pb) in soils. This study focused on the potential of applying IEK for chromate to characterize its availability in two tropical ultramafic Ferralsols. Materials and methods Two Ferralsols (NIQ II and NIQ III) of the ultramafic complex of Niquelandia (Goias, Brazil), known to have a high content of extractable chromate, were investigated. We adapted IEK for chromate in order to distinguish different pools of available chromate according to their rate of exchange kinetic. Results The extractable Cr(III) ranged from 9 to 132 mg kg{sup -1}, whereas extractable Cr(VI) ranged from 64 to 1,014 mg kg{sup -1}. The intensity factor, i.e., concentration of soluble Cr, ranged from 78 to 231 {mu}g L{sup -1} in profile NIQ II and from 6 to 141 {mu}g L{sup -1} in profile NIQ III. The highest concentrations were found in both topsoils and in the NIQ II-5 horizon. Most of the Cr(VI) was labile in short (E{sub 0-1} {sub min}) or medium-term (E{sub 1} {sub min-24} {sub h}) in both soils. The E{sub 0-1} {sub min} and E{sub 1} {sub min-24} {sub h} represented 39 to 83% of labile Cr (VI) in NIQ II and 69 to 80% in NIQ III. A high quantity of Cr(VI) was thus extremely labile and highly available, particularly in NIQ II. Moreover, both soils had a high buffering capacity of soluble Cr(VI) by labile pools. (orig.)

  2. Competitive sorption and diffusion of chromate and sulphate in a flow system with goethite in gel beads.

    Science.gov (United States)

    van Beinum, Wendy; Meeussen, Johannes C L; van Riemsdijk, Willem H

    2006-08-10

    Column experiments and model simulations were employed to evaluate the processes involved in multicomponent solute transport in a system with heterogeneous flow. Column experiments were performed with goethite embedded in polyacrylamide gel beads. The gel forms an immobile water region that can be accessed by diffusion. A two-region transport model with diffusion into spheres was combined with a surface complexation model to predict reactive transport in the goethite-gel bead system. Chromate and sulphate breakthrough curves were measured in a set of transport experiments, along with corresponding changes in the pH of the effluent. Sorption and transport of sulphate and chromate in separate columns were predicted from independently measured sorption parameters. The model overestimated the pH changes in the effluent, possibly because of proton buffering by the polyacrylamide gel. The effect of competitive sorption on transport was examined in experiments with both anions present. The model predicted the effect of competition very well in a system initially equilibrated with sulphate, followed by infiltration with chromate. However, when sulphate was infiltrated after equilibration with chromate, chromate desorption and sulphate adsorption were clearly overestimated by the transport model. The exchange between the more strongly bound chromate and the sulphate added subsequently may be too slow to cause a substantial chromate peak in the effluent. This suggests that the local equilibrium assumption was not applicable in this case.

  3. Erratum: "Utilization of the Wavefront Sensor and Short-exposure Images for Simultaneous Estimation of Quasi-static Aberration and Exoplanet Intensity" (ApJ, 767, 21)

    Science.gov (United States)

    Frazin, Richard A.

    2016-04-01

    This paper first demonstrates analytically that, at millisecond timescales, the adaptive optics system in a ground-based telescope will maintain the faint planetary emission nearly constant in time, while the speckle intensity at the planet’s location will undergo wild fluctuations. Then, it presents a method for the simultaneous determination of the image of an exo-planetary system and pupil-plane aberrations that are not corrected by the adaptive optics system (so-called “non-common path aberrations”), which cause a confounding speckle background. The central idea of the method is to take simultaneous millisecond exposures in both the wavefront sensor and science camera, and then perform statistical inference procedures to determine both the aberrations and planetary image. The statistical inference is based on a Taylor expansion of an exponential containing the aberration function. While the first order terms given in the paper are correct, it is missing some second-order terms, which are important when the aberrations are large enough so that a first order expansion is not adequate. Since the numerical experiments used small aberrations, this correction has little effect on the results.

  4. Aberrant angiogenesis: The gateway to diabetic complications

    Directory of Open Access Journals (Sweden)

    Sunil K Kota

    2012-01-01

    Full Text Available Diabetes Mellitus is a metabolic cum vascular syndrome with resultant abnormalities in both micro- and macrovasculature. The adverse long-term effects of diabetes mellitus have been described to involve many organ systems. Apart from hyperglycemia, abnormalities of angiogenesis may cause or contribute toward many of the clinical manifestations of diabetes. These are implicated in the pathogenesis of vascular abnormalities of the retina, kidneys, and fetus, impaired wound healing, increased risk of rejection of transplanted organs, and impaired formation of coronary collaterals. A perplexing feature of the aberrant angiogenesis is that excessive and insufficient angiogenesis can occur in different organs in the same individual. The current article hereby reviews the molecular mechanisms including abnormalities in growth factors, cytokines, and metabolic derangements, clinical implications, and therapeutic options of dealing with abnormal angiogenesis in diabetes.

  5. Aberrant Gene Expression in Acute Myeloid Leukaemia

    DEFF Research Database (Denmark)

    Bagger, Frederik Otzen

    model to investigate the role of telomerase in AML, we were able to translate the observed effect into human AML patients and identify specific genes involved, which also predict survival patterns in AML patients. During these studies we have applied methods for investigating differentially expressed......Summary Acute Myeloid Leukaemia (AML) is an aggressive cancer of the bone marrow, affecting formation of blood cells during haematopoiesis. This thesis presents investigation of AML using mRNA gene expression profiles (GEP) of samples extracted from the bone marrow of healthy and diseased subjects....... Here GEPs from purified healthy haematopoietic populations, with different levels of differentiation, form the basis for comparison with diseased samples. We present a mathematical transformation of mRNA microarray data to make it possible to compare AML samples, carrying expanded aberrant...

  6. METHOD OF SOFTWARE-BASED COMPENSATION OF TECHNOLOGICAL VARIATION IN CHROMATICITY COORDINATES OF LCD PANELS

    Directory of Open Access Journals (Sweden)

    I. O. Zharinov

    2015-05-01

    Full Text Available Subject of research. The problem of software-based compensation of technological variation in chromaticity coordinates of liquid crystal panels is considered. A method of software-based compensation of technological variation in chromaticity coordinates is proposed. The method provides the color reproduction characteristics of the series-produced samples on-board indication equipment corresponding to the sample equipment, which is taken as the standard. Method. Mathematical calculation of the profile is performed for the given model of the liquid crystal panel. The coefficients that correspond to the typical values of the chromaticity coordinates for the vertices of the triangle color coverage constitute a reference mathematical model of the plate LCD panel from a specific manufacturer. At the stage of incoming inspection the sample of the liquid crystal panel, that is to be implemented within indication equipment, is mounted on the lighting test unit, where Nokia-Test control is provided by the formation of the RGB codes for display the image of a homogeneous field in the red, green, blue and white. The measurement of the (x,y-chromaticity coordinates in red, green, blue and white colors is performed using a colorimeter with the known value of absolute error. Instead of using lighting equipment, such measurements may be carried out immediately on the sample indication equipment during customizing procedure. The measured values are used to calculate individual LCD-panel profile coefficients through the use of Grassman's transformation, establishing mutual relations between the XYZ-color coordinates and RGB codes to be used for displaying the image on the liquid crystal panel. The obtained coefficients are to be set into the memory of the graphics controller together with the functional software and then used for image displaying. Main results. The efficiency of the proposed method of software-based compensation for technological variation of

  7. Expressions for third-order aberration theory for holographic images

    Indian Academy of Sciences (India)

    S K Tripathy; S Ananda Rao

    2003-01-01

    Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith, Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ.

  8. An unusual case of left aberrant innominate artery with right aortic arch: evaluation with high-resolution CT

    Energy Technology Data Exchange (ETDEWEB)

    Calcagni, Giulio [University Rene Descartes-Paris 5, Department of Pediatric Cardiology, Hopital Necker Enfants Malades, Paris (France); Gesualdo, Francesco; Brunelle, Francis; Ou, Phalla [University Rene Descartes-Paris 5, Department of Pediatric Radiology, Hopital Necker Enfants Malades, Paris Cedex 15 (France)

    2008-01-15

    A left aberrant innominate (brachiocephalic) artery is an angiographically well-known entity that may cause tracheal compression. We report a male newborn who was admitted for further investigation of a prenatally suspected major vessel anomaly. High-resolution CT was used to completely assess the abnormal anatomy and the relationship with the airway, as well as to guide the surgical approach for its correction. (orig.)

  9. Age-related changes in ocular aberrations with accommodation.

    Science.gov (United States)

    Radhakrishnan, Hema; Charman, W Neil

    2007-05-30

    This study investigates the changes in aberrations with monocular accommodation as a function of age. Second-order and higher order wavefront aberrations and pupil size were measured as a function of accommodation demand over the range of 0-4 D in the right eyes of 47 normal subjects with ages between 17 and 56 years. Higher order ocular Zernike aberrations were analyzed for the natural pupil size in terms of their equivalent defocus and were also determined for fixed pupil diameters of 4.5 mm in the unaccommodated eyes and 2.5 mm in the accommodating eyes. With relaxed accommodation (0 D accommodation stimulus), the major change with age was in the value of C4(0), which increased in positive value over the age range studied, although the total higher order RMS wavefront aberration did not increase. When the data were analyzed for natural pupils, spherical aberration was again found to change systematically in the positive direction with age. The equivalent defocus of total higher order RMS error for natural pupils showed no significant correlation with age (p > .05). With active accommodation, spherical aberration was found to decrease and become negative as the accommodative response increased in the younger subjects (40 years), the spherical aberration showed only small changes, some of which were positive, within the limited amplitude of accommodation available. Other higher order aberrations and the RMS of higher order aberrations did not appear to change systematically with accommodation, except in the oldest subjects. The change with age in the relationship between aberration and accommodation is interpreted in terms of the changing gradients of refractive index and surface curvatures of the crystalline lens.

  10. Aberration-free FTIR spectroscopic imaging of live cells in microfluidic devices.

    Science.gov (United States)

    Chan, K L Andrew; Kazarian, Sergei G

    2013-07-21

    The label-free, non-destructive chemical analysis offered by FTIR spectroscopic imaging is a very attractive and potentially powerful tool for studies of live biological cells. FTIR imaging of live cells is a challenging task, due to the fact that cells are cultured in an aqueous environment. While the synchrotron facility has proven to be a valuable tool for FTIR microspectroscopic studies of single live cells, we have demonstrated that high quality infrared spectra of single live cells using an ordinary Globar source can also be obtained by adding a pair of lenses to a common transmission liquid cell. The lenses, when placed on the transmission cell window, form pseudo hemispheres which removes the refraction of light and hence improve the imaging and spectral quality of the obtained data. This study demonstrates that infrared spectra of single live cells can be obtained without the focus shifting effect at different wavenumbers, caused by the chromatic aberration. Spectra of the single cells have confirmed that the measured spectral region remains in focus across the whole range, while spectra of the single cells measured without the lenses have shown some erroneous features as a result of the shift of focus. It has also been demonstrated that the addition of lenses can be applied to the imaging of cells in microfabricated devices. We have shown that it was not possible to obtain a focused image of an isolated cell in a droplet of DPBS in oil unless the lenses are applied. The use of the approach described herein allows for well focused images of single cells in DPBS droplets to be obtained.

  11. Chromate Reductase YieF from Escherichia coli Enhances Hexavalent Chromium Resistance of Human HepG2 Cells

    Directory of Open Access Journals (Sweden)

    Xuan Liu

    2015-05-01

    Full Text Available Hexavalent chromium (Cr(VI is a serious environmental pollutant and human toxicant. Mammalian cells are very sensitive to chromate as they lack efficient chromate detoxifying strategy, e.g., chromate-reducing genes that are widely present in prokaryotes. To test whether introduction of prokaryotic chromate-reducing gene into mammalian cells could render higher chromate resistance, an Escherichia coli chromate-reducing gene yieF was transfected into human HepG2 cells. The expression of yieF was measured in stably transfected cells HepG2-YieF by quantitative RT-PCR and found up-regulated by 3.89-fold upon Cr(VI induction. In chromate-reducing ability test, HepG2-YieF cells that harbored the reductase showed significantly higher reducing ability of Cr(VI than HepG2 control cells. This result was further supported by the evidence of increased Cr(VI-removing ability of crude cell extract of HepG2-YieF. Moreover, HepG2-YieF demonstrated 10% higher viability and decreased expression of GSH synthesizing enzymes under Cr(VI stress. Subcellular localization of YieF was determined by tracing GFP-YieF fusion protein that was detected in both nucleus and cytoplasm by laser confocal microscopy. Altogether, this study successfully demonstrated that the expression of a prokaryotic Cr(VI-reducing gene yieF endowed mammalian cell HepG2 with enhanced chromate resistance, which brought new insight of Cr(VI detoxification in mammalian cells.

  12. Mutations in FMN Binding Pocket Diminish Chromate Reduction Rates for Gh-ChrR Isolated from Gluconacetobacter hansenii

    Energy Technology Data Exchange (ETDEWEB)

    Khaleel, Janin A.; Gong, Chunhong; Zhang, Yanfeng; Tan, Ruimin; Squier, Thomas C.; Jin, Hongjun

    2013-06-01

    A putative chromate ion binding site was identified proximal to a rigidly bound FMN from electron densities in the crystal structure of the quinone reductase from Gluconacetobacter hansenii (Gh-ChrR) (3s2y.pdb). To clarify the location of the chromate binding site, and to understand the role of FMN in the NADPH-dependent reduction of chromate, we have expressed and purified four mutant enzymes involving the site-specific substitution of individual side chains within the FMN binding pocket that form non-covalent bonds with the ribityl phosphate (i.e., S15A and R17A in loop 1 between β1 sheet and α1 helix) or the isoalloxanzine ring (E83A or Y84A in loop 4 between the β3 sheet and α4 helix). Mutations that selectively disrupt hydrogen bonds between either the N3 nitrogen on the isoalloxanzine ring (i.e., E83) or the ribitylphos- phoate (i.e., S15) respectively result in 50% or 70% reductions in catalytic rates of chromate reduction. In comparison, mutations that disrupt π-π ring stacking interactions with the isoal-loxanzine ring (i.e., Y84) or a salt bridge with the ribityl phosphate result in 87% and 97% inhibittion. In all cases there are minimal alterations in chromate binding affinities. Collectively, these results support the hypothesis that chromate binds proximal to FMN, and implicate a structural role for FMN positioning for optimal chromate reduction rates. As side chains proximal to the β3/α4 FMN binding loop 4 contribute to both NADH and metal ion binding, we propose a model in which structural changes around the FMN binding pocket couples to both chromate and NADH binding sites.

  13. Oxalic acid as an assisting agent for the electrodialytic remediation of chromated copper arsenate treated timber waste

    DEFF Research Database (Denmark)

    Ribeiro, Alexandra B.; Mateus, Eduardo P.; Ottosen, Lisbeth M.

    1999-01-01

    The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber.......The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber....

  14. Demonstration and Validation of a Replacement Alternative to the Chromate Wash Primer DOD-P-15328D

    Science.gov (United States)

    2006-04-01

    system. The current wash primer is a low-solids, solvent-based polyvinyl butyral that contains phosphoric acid and zinc chromate that promotes adhesion...prior to the application of an epoxy primer/polyurethane topcoat CARC system. The current wash primer is a low-solids, solvent-based polyvinyl ... butyral that contains phosphoric acid and zinc chromate that promotes adhesion and minimizes corrosion. This coating contains large amounts of volatile

  15. Single bunch transverse instability in a circular accelerator with chromaticity and space charge

    CERN Document Server

    Balbekov, V

    2015-01-01

    Transverse instability of a bunch in a circular accelerator is elaborated in this paper. New tree-modes model is proposed and developed to describe the most unstable modes of the bunch. The model includes chromaticity and space charge, and can be used with any bunch and wake forms. Dispersion relation for the bunch eigentunes is obtained in form of a third-order algebraic equation. Known head-tail and TMCI modes appear as the ultimate cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunch model but are rather sensitive to the wake shape. Resistive wall wake is considered in detail including a comparison of single and collective effects. It is shown that space charge influence depends on sign of the wake function enhancing the stability with negative one.

  16. Thermal treatment of solid waste in view of recycling: Chromate and molybdate formation and leaching behaviour.

    Science.gov (United States)

    Verbinnen, Bram; Billen, Pieter; Vandecasteele, Carlo

    2014-06-01

    Elevated Cr and Mo concentrations are often found in leachates of thermally treated solid waste, but there is no general explanation for this so far. Therefore, we studied the leaching behaviour after thermal treatment as a function of heating temperature and residence time for two types of solid waste: contaminated sludge and bottom ash from municipal solid waste incineration. The leaching behaviour of both waste streams was compared with experiments on synthetic samples, allowing deduction of a general mechanism for Cr and Mo leaching. Cr and Mo showed a similar leaching behaviour: after an initial increase, the leaching decreased again at higher temperatures. Oxidation of these elements from their lower oxidation states to chromate and molybdate at temperatures up to 600 °C was responsible for the increased leaching. At higher temperatures, both Mo and Cr leaching decreased again owing to the formation of an amorphous phase, incorporating the newly formed chromate and molybdate salts, which prevents them from leaching.

  17. Chromated copper arsenate–treated wood: a potential source of arsenic exposure and toxicity in dermatology

    Directory of Open Access Journals (Sweden)

    Amy Yuntzu-Yen Chen, MD

    2016-03-01

    Full Text Available Arsenic-contaminated drinking water presents a serious health hazard in certain geographic locations around the world. Chromated copper arsenate, a pesticide and preservative that was used to pressure treat residential lumber in the United States beginning in the 1940s and was banned by the Environmental Protection Agency in 2003, poses a potential source of arsenic exposure and toxicity. In this study, we review the clinical manifestations of arsenic intoxication with the focus on dermatologic manifestations. Dermatologists should be aware that although chromated copper arsenate-treated wood for residential use was banned in 2003, the exposure risk remains. Long-term follow up is necessary to detect arsenic induced cutaneous and visceral malignancy in patients with history of arsenic exposure.

  18. The detection of various color combinations under different chromatic ambient illuminations.

    Science.gov (United States)

    Neri, D F; Luria, S M; Kobus, D A

    1986-06-01

    Our purpose was to reveal the effects of ambient illumination color and various foreground/background color pairings on a choice reaction time task performed on a color CRT. Six men and two women with normal color vision served as observers in a four-alternative forced choice procedure. A small (18' visual angle) colored circle appeared in the center of one of the unmarked quadrants of the screen. The observer's task was to respond as quickly as possible to this target by pressing one of four buttons corresponding to its location. We found that target colors that were opponent to the background colors were most quickly detected. Detection was enhanced by maximizing both brightness and chromatic contrast, but brightness contrast was much more effective. Chromatic ambient lighting which was a log unit dimmer than the target luminance had no effect on performance.

  19. Discrimination of luminance and chromaticity differences by dichromatic and trichromatic monkeys.

    Science.gov (United States)

    Jacobs, G H

    1990-01-01

    Dichromatic and trichromatic representatives from two genera of platyrrhine monkeys that show widespread color vision polymorphism (Saguinus--tamarins, Saimiri--squirrel monkeys) were tested for their abilities to make increment-threshold and flicker discriminations based on luminance and chromaticity differences. The details of these tests were arranged to attempt to emphasize the relative contributions to visual behavior of non-opponent and spectrally-opponent neural mechanisms. The results indicate that dichromatic and trichromatic monkeys differ only trivially on tests where performance is based on the contributions of non-opponent mechanisms, that the contribution of spectrally opponent mechanisms to the "brightness signal" is very similar in trichromatic and dichromatic monkeys, and that in increment-threshold discriminations where there are both chromaticity and luminance cues some test wavelengths yield superior performance for trichromats while others appear to favor the dichromat.

  20. Psychophysical Evaluation of Achromatic and Chromatic Vision of Workers Chronically Exposed to Organic Solvents

    Directory of Open Access Journals (Sweden)

    Eliza Maria da Costa Brito Lacerda

    2012-01-01

    Full Text Available The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test—FM100. Spatial contrast sensitivities of exposed workers were lower than the control at spatial frequencies of 20 and 30 cpd whilst the temporal contrast sensitivity was preserved. Visual field losses were found in 10–30 degrees of eccentricity in the solvent exposed workers. The exposed workers group had higher error values of FM100 and wider color discrimination ellipses area compared to the controls. Workers occupationally exposed to organic solvents had abnormal visual functions, mainly color vision losses and visual field constriction.