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Parameterization of the deterministic Mueller matrix: application to a uniform medium

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2017年第4期34卷 602-608页

作者： Sheppard, Colin J. R. Ist Italiano Tecnol Nanoscopy Grp Dept Nanophys I-16163 Genoa Italy

The extraction of the elementary polarization properties of a uniform medium from a deterministic Mueller matrix has been considered by several researchers. The relationship between a parameterization of the deterministic Mueller matrix that we described recently and the elementary polarization properties for a uniform medium is investigated. The elementary polarization properties can be calculated exactly from the Mueller matrix parameters. Simplified forms for the Mueller matrix parameters in terms of the elementary polarization properties are presented. The effect on the Mueller matrix of varying the ratio of the total diattenuation to the total retardance is investigated. Approximate forms for the elementary polarization properties in terms of the Mueller matrix parameters, valid for weak optical media, are given. (C) 2017 Optical Society of America

关键词： computation methods Inverse problems Mueller matrices Optical media Polarization Wave propagation

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Color constancy through inverse-intensity chromaticity space

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2004年第3期21卷 321-334页

作者： Tan, RT Nishino, K Ikeuchi, K Univ Tokyo Dept Comp Sci Meguro Ku Tokyo 1538505 Japan Columbia Univ Dept Comp Sci New York NY 10027 USA

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. (C) 2004 Optical Society of America.

关键词： Color constancy Color reproduction computation methods Fresnel reflection Machine vision Nonlinear correlation

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Accurate and fast stray radiation calculation based on improved backward ray tracing

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APPLIED OPTICS 2013年第4期52卷 B1-B9页

作者： Liu Yang An XiaoQiang Wang Qian SW Inst Tech Phys Chengdu 610041 Si Chuan Peoples R China

An improved method of backward ray tracing is proposed according to the theory of geometrical optics and thermal radiation heat transfer. The accuracy is essentially raised comparing to the traditional backward ray tracing because ray orders and weight factors are taken into account and the process is designed as sequential and recurring steps to trace and calculate different order stray lights. Meanwhile, it needs very small computation comparing to forward ray tracing because irrelevant surfaces and rays are excluded from the tracing. The effectiveness was verified in the stray radiation analysis for a cryogenic infrared (IR) imaging system, as the results coincided with the actual stray radiation irradiance distributions in the real images. The computation amount was compared with that of forward ray tracing in the narcissus calculation for another cryogenic IR imaging system, it was found that to produce the same accuracy result, the computation of the improved backward ray tracing is far smaller than that of forward ray tracing by at least 2 orders of magnitude. (C) 2012 Optical Society of America

关键词： computation methods Geometric optics Imaging systems Infrared systems Ray tracing Stray light analysis

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Robust topology optimization of three-dimensional photonic-crystal band-gap structures

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OPTICS EXPRESS 2014年第19期22卷 22632-22648页

作者： Men, H. Lee, K. Y. K. Freund, R. M. Peraire, J. Johnson, S. G. MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA MIT Dept Math Cambridge MA 02139 USA MIT Alfred P Sloan Sch Management Cambridge MA 02142 USA

We perform full 3D topology optimization (in which "every voxel" of the unit cell is a degree of freedom) of photonic-crystal structures in order to find optimal omnidirectional band gaps for various symmetry groups, including fcc (including diamond), bcc, and simple-cubic lattices. Even without imposing the constraints of any fabrication process, the resulting optimal gaps are only slightly larger than previous hand designs, suggesting that current photonic crystals are nearly optimal in this respect. However, optimization can discover new structures, e. g. a new fcc structure with the same symmetry but slightly larger gap than the well known inverse opal, which may offer new degrees of freedom to future fabrication technologies. Furthermore, our band-gap optimization is an illustration of a computational approach to 3D dispersion engineering which is applicable to many other problems in optics, based on a novel semidefinite-program formulation for nonconvex eigenvalue optimization combined with other techniques such as a simple approach to impose symmetry constraints. We also demonstrate a technique for robust topology optimization, in which some uncertainty is included in each voxel and we optimize the worst-case gap, and we show that the resulting band gaps have increased robustness to systematic fabrication errors. (C) 2014 Optical Society of America

关键词： computation methods Inverse problems Negative refraction Nonlinear optics Phase matching Photonic crystals

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Explicit error bounds for the α-quasi-periodic Helmholtz problem

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2013年第10期30卷 2111-2123页

作者： Lord, Natacha H. Mulholland, Anthony J. Univ Strathclyde Dept Math & Stat Glasgow G1 1XH Lanark Scotland

This paper considers a finite element approach to modeling electromagnetic waves in a periodic diffraction grating. In particular, an a priori error estimate associated with the alpha-quasi-periodic transformation is derived. This involves the solution of the associated Helmholtz problem being written as a product of e(iax) and an unknown function called the alpha-quasi-periodic solution. To begin with, the well-posedness of the continuous problem is examined using a variational formulation. The problem is then discretized, and a rigorous alpha priori error estimate, which guarantees the uniqueness of this approximate solution, is derived. In previous studies, the continuity of the Dirichlet-to-Neumann map has simply been assumed and the dependency of the regularity constant on the system parameters, such as the wavenumber, has not been shown. To address this deficiency, in this paper an explicit dependence on the wavenumber and the degree of the polynomial basis in the alpha priori error estimate is obtained. Since the finite element method is well known for dealing with any geometries, comparison of numerical results obtained using the alpha-quasi-periodic transformation with a lattice sum technique is then presented. (C) 2013 Optical Society of America

关键词： Diffraction gratings Diffraction theory Gratings Mathematical methods (general) Scattering computation methods

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Stable algorithm for the computation of the electromagnetic field distribution of eigenmodes of periodic diffraction structures

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2012年第11期29卷 2307-2313页

作者： Bezus, Evgeni A. Doskolovich, Leonid L. Russian Acad Sci Image Proc Syst Inst Samara 443001 Russia Samara State Aerosp Univ Tech Cybernet Dept Samara 443001 Russia

In the present work, a stable algorithm for the calculation of the electromagnetic field distributions of the eigenmodes of one-dimensional diffraction gratings is presented. The proposed approach is based on the method for the computation of the propagation constants of Bloch waves of such structures previously presented by Cao et al. [J. Opt. Soc. Am. A 19, 335 (2002)] and uses a modified S-matrix algorithm to ensure numerical stability. (C) 2012 Optical Society of America

关键词： computation methods Diffraction gratings Electromagnetic radiation Laser resonators Propagation methods Stratified media

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Illuminant-invariant stereo matching using cost volume and confidence-based disparity refinement

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2019年第10期36卷 1768-1776页

作者： Choi, Nakeun Jang, Jinbuem Paik, Joonki Chung Ang Univ Seoul South Korea

In stereo-matching techniques for three-dimensional (3D) vision, illumination change is a major problem that degrades matching accuracy. When large intensity differences are observed between a pair of stereos, it is difficult to find the similarity in the matching process. In addition, inaccurately estimated disparities are obtained in textureless regions, since there are no distinguishable features in the region. To solve these problems, this paper presents a robust stereo-matching method using illuminant-invariant cost volume and confidence-based disparity refinement. In the step of matching a stereo pair, the proposed method combines two cost volumes using an invariant image and Weber local descriptor (WLD), which was originally motivated by human visual characteristics. The invariant image used in the matching step is insensitive to sudden brightness changes by shadow or light sources, and WLD reflects structural features of the invariant image with consideration of a gradual illumination change. After aggregating the cost using a guided filter, we refine the initially estimated disparity map based on the confidence map computed by the combined cost volume. Experimental results verify that the matching computation of the proposed method improves the accuracy of the disparity map under a radiometrically dynamic environment. Since the proposed disparity refinement method can also reduce the error of the initial disparity map in textureless areas, it can be applied to various 3D vision systems such as industrial robots and autonomous vehicles. (C) 2019 Optical Society of America

关键词： Color spaces computation methods Face recognition Light sources Object detection Stereo matching

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A systematic analysis for the quantitative comparison of phase retrieval methods based on alternating projections

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OPTICS AND LASERS IN ENGINEERING 2018年第Jul.期106卷 24-31页

作者： Veiras, Francisco E. Bianchetti, Arturo Etchepareborda, Pablo Vadnjal, Ana L. Federico, Alejandro Univ Buenos Aires Fac Ingn Dept Fis GLOmAe CONICET C1063ACV Buenos Aires DF Argentina Inst Nacl Tecnol Ind Elect & Informat POB B1650WABB1650KNA San Martin Argentina Consejo Nacl Invest Cient & Tecn Elect & Informat Inst Nacl Tecnol Ind POB B1650WAB BI650KNA San Martin Argentina

We present a numerical and experimental scheme for the systematic analysis and comparison of phase retrieval techniques based on alternating projection numerical methods. This comparison allows us to evaluate the most common and recently introduced phase retrieval methods. The proposed scheme gives a quantitative comparison that helps to elucidate the differences between them and develop proper technical implementations of phase retrieval. The comparison is made by means of a numerical and experimental scheme that allows us to evaluate phase retrieval experiments. In this work, the drawbacks of using arbitrary random initial seeds to support the phase retrieval numerical algorithms are also analyzed and discussed. Moreover, we show the convenience of using a rough object phase estimation, which is obtained by means of a simple holographic technique, as the initial seed. This seed dramatically reduces the computational load of the algorithms by decreasing the successive iterations from hundreds to less than twenty. The experimental object under study is a random phase object within a micro-channel. As a proof of concept, this micro-channel combined with a millimeter size semicircular hole, which provides a reference wave, conforms a primitive sensor. The performance of the algorithms is not only measured by the usual convergence error, but also by means of a quality index that requires a direct comparison against the generally unknown original phase object. Thus, in order to evaluate the experimental performance of the phase retrieval techniques, we implement an interferometric optical setup that allows us to compare the results obtained by both techniques. The experiment proposed is a valuable tool for quantitative experimental evaluation of phase retrieval techniques in the optical domain. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Phase retrieval Metrological instrumentation computation methods

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Electromagnetic response and optical properties of anisotropic CuSbS2 nanoparticles

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2022年第7期39卷 1743-1751页

作者： Seyedheydari, Fahime Conley, Kevin Yla-Oijala, Pasi Sihvola, Ari Ala-Nissila, Tapio Aalto Univ Dept Appl Phys Espoo Finland Aalto Univ Dept Chem & Mat Sci Espoo Finland Aalto Univ Dept Elect & Nanoengn Espoo Finland Loughborough Univ Interdisciplinary Ctr Math Modelling Dept Math Sci Loughborough Leics England

We investigate the electromagnetic response of anisotropic (non-spherical) copper antimony disulfide (CuSbS2) nanoparticles and layers embedded with them using computational methods. To this end, we calculate the scattering and absorption efficiencies of oblate spheroidal CuSbS2 nanoparticles using the surface integral equation method. We find strong dependence of the response depending on the anisotropy of the spheroids and their orientation with respect to the electric field polarization of incoming radiation. Thin spheroids display a sharp plasmonic resonance in the ultraviolet, which is observed only for the electric field polarization along the short axis. Fano resonances that appear in the near infrared (NIR) blueshift when the short axis length is reduced, and they can be either strongly suppressed or enhanced depending on the relative orientation of the spheroid. We further investigate the optical response of thin layers containing CuSbS2 spheroids at a low volume fraction using a Monte Carlo method. We find that the response of these layers can be considerably modified by changing the short axis length and the orientation of particles within the layer with respect to polarization. Our results demonstrate the potential of anisotropic dielectric particles for polarization-dependent-response applications such as solar devices and NIR sensors. (C) 2022 Optica Publishing Group

关键词： computation methods Effective medium theory Fano resonance Finite difference time domain Polarization Resonance

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Nonlinear optimization approach for Fourier ptychographic microscopy

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OPTICS EXPRESS 2015年第26期23卷 33822-33835页

作者： Zhang, Yongbing Jiang, Weixin Dai, Qionghai Tsinghua Univ Grad Sch Shenzhen Shenzhen Key Lab Broadband Network & Multimedia Shenzhen 518055 Peoples R China Tsinghua Univ Dept Automat Beijing 100084 Peoples R China

Fourier ptychographic microscopy (FPM) is recently proposed as a computational imaging method to bypass the limitation of the space-bandwidth product of the traditional optical system. It employs a sequence of low-resolution images captured under angularly varying illumination and applies the phase retrieval algorithm to iteratively reconstruct a wide-field, high-resolution image. In current FPM imaging system, system uncertainties, such as the pupil aberration of the employed optics, may significantly degrade the quality of the reconstruction. In this paper, we develop and test a nonlinear optimization algorithm to improve the robustness of the FPM imaging system by simultaneously considering the reconstruction and the system imperfections. Analytical expressions for the gradient of a squared-error metric with respect to the object and illumination allow joint optimization of the object and system parameters. The algorithm achieves superior reconstructions when the system parameters are inaccurately known or in the presence of noise and corrects the pupil aberrations simultaneously. Experiments on both synthetic and real captured data validate the effectiveness of the proposed method. (C) 2015 Optical Society of America

关键词： computation methods Eyes Optical microscopy Phase retrieval Point spread function Pupil

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