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Wollaston prism-based structured illumination microscope with tunable frequency

APPLIED OPTICS 2019年第7期58卷 B1-B8页

作者： Doblas, Ana Bedoya, Sebastian Preza, Chrysanthe Univ Memphis Dept Elect & Comp Engn Memphis TN 38152 USA

This work proposes an alternative structured illumination (SI) system based on a Wollaston prism (WP) illuminated by the diffracted field of an incoherent linear source. The proposed WP-based SI system presents several advantages. First, the generated fringes can be approximated by a pure sinusoidal pattern;thereby, computational methods developed for sinusoidal SI can be used without the need for additional processing. Second, the SI pattern's period can be continuously varied up to the cutoff frequency of the native widefield system. Most significantly, the phase shifting of the SI pattern required for demodulation in SI microscopy can be easily accomplished using a de Senarmont compensator, which provides accurate lateral displacement of the fringes independently of the lateral modulation frequency. Experimental verifications confirm the presented theoretical predictions. (C) 2019 Optical Society of America

关键词： computation methods Modulation transfer function Phase shift Spatial light modulators Structured illumination microscopy Wollaston prisms

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Training of photonic neural networks through in situ backpropagation and gradient measurement

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OPTICA 2018年第7期5卷 864-871页

作者： Hughes, Tyler W. Minkov, Momchil Shi, Yu Fan, Shanhui Stanford Univ Dept Appl Phys Stanford CA 94305 USA Stanford Univ Ginzton Lab Stanford CA 94305 USA Stanford Univ Dept Elect Engn Stanford CA 94305 USA

Recently, integrated optics has gained interest as a hardware platform for implementing machine learning algorithms. Of particular interest are artificial neural networks, since matrix-vector multiplications, which are used heavily in artificial neural networks, can be done efficiently in photonic circuits. The training of an artificial neural network is a crucial step in its application. However, currently on the integrated photonics platform there is no efficient protocol for the training of these networks. In this work, we introduce a method that enables highly efficient, in situ training of a photonic neural network. We use adjoint variable methods to derive the photonic analogue of the backpropagation algorithm, which is the standard method for computing gradients of conventional neural networks. We further show how these gradients may be obtained exactly by performing intensity measurements within the device. As an application, we demonstrate the training of a numerically simulated photonic artificial neural network. Beyond the training of photonic machine learning implementations, our method may also be of broad interest to experimental sensitivity analysis of photonic systems and the optimization of reconfigurable optics platforms. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： computation methods Integrated photonics Neural networks Optical signals Optical systems Phased arrays

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Non-approximated Rayleigh-Sommerfeld diffraction integral: advantages and disadvantages in he propagation of complex wave fields

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APPLIED OPTICS 2019年第34期58卷 G11-G18页

作者： Buitrago-Duque, Carlos Garcia-Sucerquia, Jorge Univ Nacl Colombia Sede Medellin Sch Phys AA 3840 Medellin 050034 Colombia

Advantages and disadvantages of the non-approximated numerical implementation of the Rayleigh-Sommerfeld diffraction integral (RSD) are revisited. In this work, it is shown that as trade-off for its large computation load, the non-approximated RSD removes any limitation on the propagation range and does not introduce any artifact in the computed wave field. A non-approximated CPU implementation of the RSD is contrasted with the angular spectrum, the Fresnel transform, and a fast Fourier transform implementation of the RSD. The forecasted phase shift introduced in the propagated wave fields as light is diffracted on complementary apertures and utilized as a metric to quantify the performance of the tested methods. An application to numerical reconstructions with arbitrary shape and size of digital recorded holograms from digital lensless holographic microscopy is presented. (C) 2019 Optical Society of America

关键词： computation methods Discrete Fourier transforms Fast Fourier transforms Light fields Phase shift Spatial frequency

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Modeling of transmission characteristics in step-index polymer optical fiber using the matrix exponential method

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APPLIED OPTICS 2018年第31期57卷 9203-9207页

作者： Stepniak, Grzegorz Siuzdak, Jerzy Warsaw Univ Technol Inst Telecommun Nowowiejska 15-19 PL-00665 Warsaw Poland

In this paper, we propose to calculate the impulse and frequency response of step-index polymer optical fiber in the presence of mode coupling using the matrix exponential method. The computation time in this method is independent of the fiber length and is typically 2 orders of magnitude shortened compared with the standard numerical procedures involving finite difference methods. Results obtained with our method are compared with those of known cases, where an analytical solution for the time-dependent power flow equation exists, and with a finite difference method. We also investigate the impact of mode coupling and differential modal attenuation on impulse response duration and shape. (C) 2018 Optical Society of America

关键词： computation methods Diode lasers High numerical aperture optics Multimode fibers Plastic optical fibers Step index fibers

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Fault Detection Based on Multi-objective Observer and Interval Hull computation

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IFAC-PapersOnLine 2018年第24期51卷 332-337页

作者： Tang, Wentao Wang, Zhenhua Shen, Yi Rodrigues, Mickael Theilliol, Didier School of Astronautics Harbin Institute of Technology Harbin150001 China Automatic and Process Control Laboratory University of Lyon LyonF-69003 France Centre de Recherche en Automatique de Nancy Université de Lorraine CNRS UMR 7039 Vandoeuvre-les-NancyF-54506 France

The design of a novel sensor fault detection scheme for discrete-time linear time-invariant systems with unknown but bounded uncertainties is proposed in the paper. To make the residual sensitive to fault and robust against the unknown disturbance and measurement noise, we propose a multi-objective fault detection observer method based on the criteria of H-index and P-radius and further present an iterative LMI method to solve the observer design problem. In the design of residual evaluation, we propose a threshold computation method via the interval hull approximation of the residual reachable set. The merit of the proposed method is that its threshold computation exhibits less conservatism and higher computational efficiency than the zonotope-based method. Simulations are conducted to demonstrate the superiority of the proposed method. © 2018

关键词： Fault detection computational efficiency Invariance Iterative methods Linear systems Nonlinear control systems Time varying control systems computation methods Discrete time linear time invariant systems Measurement Noise Multi objective Observer design Sensor fault detection Unknown but bounded Unknown disturbance

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A skew freeform reflector design method for prescribed off-axis irradiance

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RESULTS IN PHYSICS 2019年 13卷 102193-000页

作者： Su, Jian-Jia Tien, Chung-Hao Tsai, Yu-Lin Wu, Chin-Tien Natl Chiao Tung Univ Dept Photon Coll Elect & Comp Engn Hsinchu 30010 Taiwan Natl Space Org 8F 9 Prosper 1st RdHsinchu Sci Pk Hsinchu 30078 Taiwan Natl Chiao Tung Univ Dept Appl Math Hsinchu 30010 Taiwan

In this paper we proposed a new methodology for designing freeform reflectors tailored to redistribute the radiant flux emitted by a point light source onto a target plane with the prescribed irradiance pattern. Based on the laws of reflection and energy conservation, a skew freeform model with a set of second-order ordinary differential equations formulating the ray tracing between the source and target domain was presented. A 3D freeform reflector was constructed by using such skew freeform model with quadric surface fitting accordingly. Proposed scheme is applicable for arbitrary geometric-based mapping without the restrictions subject to the target, source, collective solid angle, or target topography, respectively.

关键词： Geometric optical design Non-imaging optics Illumination design computation methods

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A Mapping Algorithm Based on Particle Swarm Optimization for Minimizing Cost and Delay in Sliceable Fiber-Wireless Access Networks

A Mapping Algorithm Based on Particle Swarm Optimization for...

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Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Sicong Ding Shan Yin Zhan Zhang Shanguo Huang State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing P. R. China

This paper proposes a heuristic algorithm based on particle swarm optimization for the slice mapping problem in sliceable fiber-wireless access networks. Simulation shows the algorithm maximizes comprehensive performa... 详细信息

ISBN: (纸本)9781943580705

关键词： Algorithms computation methods Fiber networks Microwaves Optical wireless communication

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Design of Freeform Illumination Optics

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LASER & PHOTONICS REVIEWS 2018年第7期12卷 1700310-1700310页

作者： Wu, Rengmao Feng, Zexin Zheng, Zhenrong Liang, Rongguang Benitez, Pablo Minano, Juan C. Duerr, Fabian Zhejiang Univ State Key Lab Modern Opt Instrumentat Hangzhou 310027 Zhejiang Peoples R China Zhejiang Univ Coll Opt Sci & Engn Hangzhou 310027 Zhejiang Peoples R China Beijing Inst Technol Sch Opt & Photon Beijing Engn Res Ctr Mixed Real & Adv Display Beijing 100081 Peoples R China Univ Arizona Coll Opt Sci Tucson AZ 85721 USA Univ Politecn Madrid Cedint Campus Montegancedo Madrid 28223 Spain Flanders Make Pl Laan 2 B-1050 Brussels Belgium Vrije Univ Brussel Brussels Photon Dept Appl Phys & Photon Pl Laan 2 B-1050 Brussels Belgium

Freeform optics constitutes a new technology that is currently driving substantial changes in illumination design. It liberates designers and engineers from restrictions of optical surface geometry, enabling them to achieve compact, lightweight, and efficient illumination systems with excellent optical performance. Freeform optics is currently used widely for both fundamental research and practical applications. This Review focuses on the design of freeform illumination optics, which is a key factor in advancing the development of illumination engineering. The design methods of freeform illumination optics can be divided into two groups: zero-etendue algorithms based on ideal source assumption and design algorithms for extended light sources. The zero-etendue algorithms include ray mapping method, Monge-Ampere equation method, and supporting quadric method. The algorithms for extended sources include illumination optimization, feedback design, and simultaneous multiple surfaces method. The characteristics and limitations of these design methods are illustrated and a summary of these methods with future outlooks is also given.

关键词： computation methods freeform optics illumination design nonimaging optics

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Raman spectra and optical properties of the chalcogen-hyperdoped silicon: a first-principles study

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OPTICS EXPRESS 2018年第18期26卷 A796-A805页

作者： Dong, Xiao Fang, Xiuxiu Wang, Yongyong Song, Xiaohui Henan Normal Univ Coll Phys & Mat Sci Xinxiang 953007 Peoples R China Henan Key Lab Photovolta Mat Xinxiang 453007 Peoples R China

The Raman peaks observed in the ultrafast-laser induced chalcogen-hyperdoped Si are assigned to different configurations of defects formed in crystal Si. The disappearance of the Raman peaks of the chalcogen-hyperdoped Si after thermal annealing is attributed to the formation of polymers, which cannot display any Raman peaks except the strong peak of crystal Si. The imaginary parts of the dielectric functions indicate that sub-bandgap absorptions are also reduced when the chalcogen atoms combine to form a polymer. The reductions of the sub-bandgap absorptions are different for S- and Se-hyperdoped Si, which can give a good explanation for their different variations of infrared absorptance at the same annealing conditions. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： computation methods Laser irradiation Optical properties Pulsed operation Raman spectroscopy Solar cells

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Flow-mediated dilatation test using optoacoustic imaging: a proof-of-concept

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BIOMEDICAL OPTICS EXPRESS 2017年第7期8卷 3395-3403页

作者： Karlas, Angelos Reber, Josefine Diot, Gael Bozhko, Dmitry Anastasopoulou, Maria Ibrahim, Tareq Schwaiger, Markus Hyafil, Fabien Ntziachristos, Vasilis HelmholtzZentrum Munchen Inst Biol & Med Imaging D-85764 Neuherberg Germany TUM Munich Sch Bioengn D-81675 Munich Germany Klinikum Rechts Der Isar Dept Cardiol Ismaningerstr 22 D-81675 Munich Germany Klinikum Rechts Der Isar Dept Nucl Med Ismaningerstr 22 D-81675 Munich Germany Univ Diderot Bichat Univ Hosp Dept Nucl Med Inserm 1148 Paris France

Label-free multispectral optoacoustic tomography (MSOT) has recently shown superior performance in visualizing the morphology of human vasculature, especially of smaller vessels, compared to ultrasonography. Herein, we extend these observations towards MSOT interrogation of macrovascular endothelial function. We employed a real-time handheld MSOT scanner to assess flow-mediated dilatation (FMD), a technique used to characterize endothelial function. A data processing scheme was developed to quantify the dimensions and diameter changes of arteries in humans and determine wall distensibility parameters. By enabling high-resolution delineation of the blood-vessel wall in a crosssectional fashion, the findings suggest MSOT as a capable alternative to ultrasonography for clinical FMD measurements. (C) 2017 Optical Society of America

关键词： Cardiovascular applications computation methods Detector arrays Image quality Temporal resolution Tomographic image reconstruction

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