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Efficient marching solver for a class of three-dimensional optical waveguides

OPTICS EXPRESS 2018年第12期26卷 15110-15123页

作者： Zhu, Jianxin Yang, Hao Jinan Univ Dept Math Guangzhou 510632 Guangdong Peoples R China Zhejiang Univ City Coll Sch Comp & Comp Sci Hangzhou 310015 Zhejiang Peoples R China

An efficient marching method of the wave propagation computation in the three-dimensional (3D) rectangular box is developed by solving the scalar Helmholtz equation with the weakly range-dependent refractive-index or wavenumber profile. The method is based on the application of the one-way formulation accompanied by a truncated technique that allows for the reduction of the number of eigenmodes and for quickly achieving reliable numerical results. The merits of the high accuracy and fast computation with a larger range step are shown to solve the equation. This treatment can be also applied to other complicated 3D waveguides. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

关键词： computation methods Fourier transforms Inhomogeneous optical media Numerical simulation Refractive index Wave propagation

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Capacitance extraction for electrostatic multiconductor problems by on-surface MEI

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IEEE TRANSACTIONS ON ADVANCED PACKAGING 2000年第3期23卷 489-494页

作者： Liu, YW Lan, K Mei, KK City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China

In this paper, on-surface measured equation of invariance (OSMEI) method is implemented to capacitance extraction of electrostatic multiconductor interconnect problems. OSMEI uses the same mesh as that in method of moment (MoM), but generates highly sparse matrices rather than a full matrix. In comparison with "standard" MEI which contains a few of finite difference (FD) or finite element (FE) mesh layers, the number of unknowns and the computation memory can be greatly saved. For each OSMEI equation in the multiconductor interconnects, a given node on a given conductor is forced to coupling with the few adjacent nodes on conductor itself and the few sampled nodes on other conductors. Thus, the system sparse matrices can be generated. The convergent behavior of the capacitance with the number of the nodes in the OSMEI equations has been widely investigated. Numerical examples of the capacitance extraction for two-dimensional (2-D) and three-dimensional (3-D) multiconductor interconnects show that the computing errors are within 2-4%. The OSMEI method may become a powerful technique for the more complex interconnect problems.

关键词： computation methods parameter extraction

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Fourier lightfield microscopy: a practical design guide

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APPLIED OPTICS 2022年第10期61卷 2558-2564页

作者： Galdon, Laura Saavedra, Genaro Garcia-Sucerquia, Jorge Martinez-Corral, Manuel Sanchez-Ortiga, Emilio Univ Valencia Dept Opt 3D Imaging & Display Lab E-46100 Burjassot Spain Univ Nacl Colombia Sede Medellin Sch Phys AA 3840 Medellin 050034 Colombia

In this work, a practical guide for the design of a Fourier lightfield microscope is reported. The fundamentals of the Fourier lightfield are presented and condensed on a set of contour plots from which the user can select the design values of the spatial resolution, the field of view, and the depth of field, as function of the specifications of the hardware of the host microscope. This work guides the reader to select the parameters of the infinity-corrected microscope objective, the optical relay lenses, the aperture stop, the microlens array, and the digital camera. A user-friendly graphic calculator is included to ease the design, even to those who are not familiar with the lightfield technology. The guide is aimed to simplify the design process of a Fourier lightfield microscope, which sometimes could be a daunting task, and in this way, to invite the widespread use of this technology. An example of a design and experimental results on imaging different types of samples is also presented. (C) 2022 Optica Publishing Group

关键词： computation methods Image processing Integral photography Microscopy Spatial resolution Three dimensional imaging

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Hybrid full-pose parameter calibration of a freeform illuminator for Fourier ptychographic microscopy

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BIOMEDICAL OPTICS EXPRESS 2023年第8期14卷 4156-4169页

作者： Zhou, Guocheng Li, Tong Zhang, Shaohui Hao, Qun Beijing Inst Technol Sch Opt & Photon Beijing 100081 Peoples R China

As a typical computational method, Fourier ptychographic microscopy (FPM) can realize high spatial resolution and quantitative phase imaging while preserving the large field of view with a low numerical aperture (NA) objective. A programmable light-emitting diode (LED) array is used as a typical illuminator in an FPM system, and the illumination parameters of each LED element are crucial to the success of the FPM reconstruction algorithm. Compared with LED arrays arranged in rectangular arrays, LED arrays with special structures such as domes or rings can effectively improve FPM imaging results and imaging efficiency. As a trade-off, their calibration difficulty is greatly increased due to the lack of geometric constraints of rectangular arrays. In this paper, we propose an effective hybrid full-pose parameter calibration method for freeform LED array illuminators, combining stereoscopic 3D imaging techniques and the geometric constraints of the microscopic platform. First, a stereovision system is used to obtain the accurate 3D position of each LED element of the freeform illuminator and to construct a rigid 3D coordinate LED array system. Then, calibration between the coordinate system of the LED array and that of the optical imaging component is realized according to the geometric features of the brightfield-to-darkfield edges. Finally, we verify the feasibility and effectiveness of the proposed method through full-pose parameter calibration of LED arrays with different arrangement rules. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： computation methods High numerical aperture optics Imaging techniques LED lighting Spatial resolution Three dimensional imaging

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Spatio-temporal Hotelling observer for signal detection from image sequences

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OPTICS EXPRESS 2009年第13期17卷 10946-10958页

作者： Caucci, Luca Barrett, Harrison H. Rodriguez, Jeffrey J. Univ Arizona Coll Opt Sci Tucson AZ 85721 USA Univ Arizona Ctr Gamma Ray Imaging Tucson AZ 85724 USA Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA

Detection of signals in noisy images is necessary in many applications, including astronomy and medical imaging. The optimal linear observer for performing a detection task, called the Hotelling observer in the medical literature, can be regarded as a generalization of the familiar prewhitening matched filter. Performance on the detection task is limited by randomness in the image data, which stems from randomness in the object, randomness in the imaging system, and randomness in the detector outputs due to photon and readout noise, and the Hotelling observer accounts for all of these effects in an optimal way. If multiple temporal frames of images are acquired, the resulting data set is a spatio-temporal random process, and the Hotelling observer becomes a spatio-temporal linear operator. This paper discusses the theory of the spatio-temporal Hotelling observer and estimation of the required spatio-temporal covariance matrices. It also presents a parallel implementation of the observer on a cluster of Sony PLAYSTATION 3 gaming consoles. As an example, we consider the use of the spatio-temporal Hotelling observer for exoplanet detection. (C) 2009 Optical Society of America

关键词： Adaptive optics computation methods Detector arrays Gamma ray imaging Medical imaging Stochastic processes

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Dirichlet-to-Neumann map method for analyzing hole arrays in a slab

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2010年第12期27卷 2568-2579页

作者： Yuan, Lijun Lu, Ya Yan City Univ Hong Kong Dept Math Kowloon Hong Kong Peoples R China

A rigorous and efficient computational method is developed to calculate transmission and reflection spectra for a finite number of air-hole arrays in a slab, where the incident waves are propagating modes of the slab. The method is a three-dimensional extension of the Dirichlet-to-Neumann (DtN) map method previously developed for ideal two-dimensional photonic crystals which are infinite and invariant in one spatial direction. The method relies on the DtN maps of the unit cells to avoid repeated calculations in identical unit cells. The DtN map of a unit cell is constructed using eigenmode expansions in the vertical direction (perpendicular to the slab) and cylindrical wave expansions in the horizontal directions. (C) 2010 Optical Society of America

关键词： computation methods Finite element method Photonic crystals Refractive index Three dimensional fabrication Waveguide modes

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First-principle calculation of Chern number in gyrotropic photonic crystals

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OPTICS EXPRESS 2020年第4期28卷 4638-4649页

作者： Zhao, Ran Xie, Guo-Da Chen, Menglin L. N. Lan, Zhihao Huang, Zhixiang Sha, Wei E., I Anhui Univ Key Lab Intelligent Comp & Signal Proc Minist Educ Hefei 230039 Peoples R China Dept Educ Anhui Prov Key Lab Electromagnet Environm Sensing Hefei 230039 Peoples R China Univ Hong Kong Dept Elect & Elect Engn Hong Kong Peoples R China UCL Dept Elect & Elect Engn London England Zhejiang Univ Coll Informat Sci Elect Engn Key Lab Micronano Elect Devices & Smart Syst Zhej Hangzhou 310027 Peoples R China

As an important figure of merit for characterizing the quantized collective behaviors of the wavefunction, Chern number is the topological invariant of quantum Hall insulators. Chern number also identifies the topological properties of the photonic topological insulators (PTIs), thus it is of crucial importance in PTI design. In this paper, we develop a first principle computatioal method for the Chern number of 2D gyrotropic photonic crystals (PCs), starting from the Maxwell's equations. Firstly, we solve the Hermitian generalized eigenvalue equation reformulated from the Maxwell's equations by using the full-wave finite-difference frequency-domain (FDFD) method. Then the Chern number is obtained by calculating the integral of Berry curvature over the first Brillouin zone. Numerical examples of both transverse-electric (TE) and transverse-magnetic (TM) modes are demonstrated, where convergent Chern numbers can be obtained using rather coarse grids, thus validating the efficiency and accuracy of the proposed method. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： computation methods Condensed matter Electric fields Magnetic fields Material properties Photonic crystals

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Accelerated and high-quality Fourier ptychographic method using a double truncated Wirtinger criteria

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OPTICS EXPRESS 2018年第20期26卷 26556-26565页

作者： Liu, Jian Li, Yong Wang, Weibo Tan, Jiubin Liu, Chenguang Harbin Inst Technol Inst Ultraprecis Optoelect Instrument Engn Harbin 150001 Heilongjiang Peoples R China Harbin Inst Technol Space Environm Simulat Res Infrastruct Harbin 150001 Heilongjiang Peoples R China

Fourier ptychographic microscopy (FPM) is a recently developed computational microscopy technique for wide-field-of-view and super-resolution complex imaging. Wirtinger-flow-based methods can effectively suppress noise and reduce data acquisition time, but they are time-consuming during the phase reconstruction. In this paper, we present a Wirtinger-flow-based reconstruction method for FPM, which combines the Poisson maximum likelihood objective function, improved truncated Wirtinger criteria, and improved adaptive momentum method. Both the simulation and experimental results demonstrate that the proposed method runs faster and the reconstruction quality is similar to or better than other state-of-the-art Wirtinger-flow-based methods. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Aperture synthesis computation methods Fourier transforms Optical microscopy Phase retrieval Superresolution

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Analytical approach to dynamics of reverse saturable absorbers

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2000年第11期17卷 1884-1893页

作者： Kobyakov, A Hagan, DJ Van Stryland, EW Univ Cent Florida Sch Opt Ctr Res & Educ Opt & Lasers Orlando FL 32816 USA

We develop an analytical approach to the dynamics of band populations of reverse saturable absorbers modeled by the three-level approximation of the five-level rate equations. We find high-accuracy approximate solutions to these rate equations, taking into account the temporal shape of the incident laser pulse for different regimes of excitation. The results obtained are confirmed by direct numerical integration of the rate equations and are verified by solution of the full system of the rate and the propagation equations. The validity ranges of the approximations are determined. We also prove that for input pulses that are much longer than the lifetime of the first excited state the ground-state depletion obeys the same functional dependence on the input fluence as in the case of rectangular input pulses. The dynamics of the excited states, however, explicitly depends on the pulse shape. We quantitatively estimate the effect of various parameters on the nonlinear absorption coefficient and discuss implementation of the approach by a beam propagation method to reduce the computational time. (C) 2000 Optical Society of America [S0740-3224(00)01711-2].

关键词： Absorption coefficient computation methods Nonlinear absorption Optical limiting Propagation methods Reverse saturable absorbers

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COOPERATIVE INTEGRATION OF STEREOPSIS AND OPTIC FLOW computation

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 1995年第12期12卷 2564-2572页

作者： SUDHIR, G BANERJEE, S BISWAS, KK BAHL, R INDIAN INST TECHNOL DEPT COMP SCI & ENGNNEW DELHI 110016INDIA INDIAN INST TECHNOL CTR APPL RES ELECTRNEW DELHI 110016INDIA

A cooperative integration of stereopsis and optic flow computation is presented. Central to our approach is the modeling of the visual processes as a sequence of coupled Markov random fields by definition of suitable interprocess interactions based on some natural constraints. The integration makes each of the individual processes better constrained and more reliable. Further, as a result of the integration, it becomes possible to obtain accurately the discontinuities in both the flow and the disparity fields along with the regions of stereo occlusion. Results on both noisy synthetic image data and real images are presented. (C) 1995 Optical Society of America

关键词： computation methods Motion detection Optical flow Stereo matching Stereopsis Vision modeling

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