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Analysis of short range forces in optomechanical devices with a nanogap

OPTICS EXPRESS 2010年第12期18卷 12615-12621页

作者： Pernice, Wolfram H. P. Li, Mo Garcia-Sanchez, Daniel Tang, Hong X. Yale Univ Dept Elect Engn New Haven CT 06511 USA

We employ the finite-difference time-domain method to calculate the dominant short range forces in optomechanical devices, Casimir and gradient optical forces. Numerical results are obtained for typical silicon optomechanical devices and are compared to metallic reference structures, taking into account geometric and frequency dispersion of silicon. Our results indicate that although a small gap is desirable for operating optomechanical devices, the Casimir force offsets the gradient force in strongly coupled optomechanical devices, which has to be taken into account in the design of optical force tunable devices. (C) 2010 Optical Society of America

关键词： computation methods Dielectric waveguides Numerical simulation Optical force Tunable filters Waveguide modes

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Morphological variations to a ptychographic algorithm

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APPLIED OPTICS 2022年第22期61卷 6561-6570页

作者： Salinas, F. Solis-Prosser, M. A. Univ La Frontera Fac Ingn & Ciencias Dept Ciencias Fis Ave Francisco Salazar Temuco 01145 Chile

Ptychography is a technique widely used in microscopy for achieving high-resolution imaging. This method relies on computational processing of images gathered from diffraction patterns produced by several partial illuminations of a sample. We numerically studied the effect of using different shapes for illuminating the aforementioned sample: convex shapes, such as circles and regular polygons, and unconnected shapes that resemble a QR code. Our results suggest that the use of unconnected shapes seems to outperform convex shapes in terms of convergence and, in some cases, accuracy. (C) 2022 Optica Publishing Group

关键词： computation methods Optical imaging Phase retrieval Spatial light modulators Speckle noise X ray imaging

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Convolutional neural network-based common-path optical coherence tomography A-scan boundary-tracking training and validation using a parallel Monte Carlo synthetic dataset

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OPTICS EXPRESS 2022年第14期30卷 25876-25890页

作者： Guo, Shoujing Kang, Jin U. Johns Hopkins Univ Dept Elect & Comp Engn 3400 N Charles St Baltimore MD 21218 USA

We present a parallel Monte Carlo (MC) simulation platform for rapidly generating synthetic common-path optical coherence tomography (CP-OCT) A-scan image dataset for image-guided needle insertion. The computation time of the method has been evaluated on different configurations and 100000 A-scan images are generated based on 50 different eye models. The synthetic dataset is used to train an end-to-end convolutional neural network (Ascan-Net) to localize the Descemet's membrane (DM) during the needle insertion. The trained Ascan-Net has been tested on the A-scan images collected from the ex-vivo human and porcine cornea as well as simulated data and shows improved tracking accuracy compared to the result by using the Canny-edge detector. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： computation methods Fiber optic sensors Image quality Laser beams Multiple scattering Optical coherence tomography

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Out-of-core GPU 2D-shift-FFT algorithm for ultra-high-resolution hologram generation

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OPTICS EXPRESS 2021年第12期29卷 19094-19112页

作者： Lee, Jaehong Kang, Homin Yeom, Han-ju Cheon, Sanghoon Park, Joongki Kim, Duksu Korea Univ Technol & Educ KOREATECH Sch Comp Engn Cheonan South Korea Elect & Telecommun Res Inst ETRI Daejeon South Korea

We propose a novel out-of-core GPU algorithm for 2D-Shift-FFT (i.e., 2D-FFT with FFT-shift) to generate ultra-high-resolution holograms. Generating an ultra-high-resolution hologram requires a large complex matrix (e.g., 100K(2)) with a size that typically exceeds GPU memory. To handle such a large-scale hologram plane with limited GPU memory, we employ a 1D-FFT based 2D-FFT computation method. We transpose the column data to have a continuous memory layout to improve the column-wise 1D-FFT stage performance in both the data communication and GPU computation. We also combine the FFT-shift and transposition steps to reduce and hide the workload. To maximize the GPU utilization efficiency, we exploit the concurrent execution ability of recent heterogeneous computing systems. We also further optimize our method's performance with our cache-friendly chunk generation algorithm and pinned-memory buffer approach. We tested our method on three computing systems having different GPUs and various sizes of complex matrices. Compared to the conventional implementation based on the state-of-the-art GPU FFT library (i.e., cuFFT), our method achieved up to 3.24 and 3.06 times higher performance for a large-scale complex matrix in single- and double-precision cases, respectively. To assess the benefits offered by the proposed approach in an actual application, we applied our method to the layer-based CGH process. As a result, it reduced the time required to generate an ultra-high-resolution hologram (e.g., 100K(2)) up to 28% compared to the use of the conventional algorithm. These results demonstrate the efficiency and usefulness of our method. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Algorithms computation methods Digital holographic imaging Fast Fourier transforms Fourier transforms Image processing

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COMPARISON OF CALCULATED AND MEASURED PERFORMANCE OF DIFFUSED CHANNEL-WAVEGUIDE COUPLERS

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA 1983年第10期73卷 1296-1304页

作者： FEIT, MD FLECK, JA MCCAUGHAN, L BELL TEL LABS INC ALLENTOWNPA 18103

Diffused channel-waveguide couplers were fabricated on z -cut y -propagating LiNbO 3 crystals by the indiffusion of titanium. Both mode spot sizes and coupling lengths were measured. The fields and coupling lengths were computed for both TM and TE polarizations from fabrication conditions. Good agreement was obtained between the measured and computed mode spot sizes and coupling lengths. It is concluded that the calculation method could aid in the design of such couplers.

关键词： Channeled waveguides computation methods Electromagnetic theory Fourier transforms Integrated optical devices Waveguide design

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Monte Carlo and multicomponent approximation methods for vector radiative transfer by use of effective Mueller matrix calculations

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APPLIED OPTICS 2001年第3期40卷 400-412页

作者： Tynes, HH Kattawar, GW Zege, EP Katsev, IL Prikhach, AS Chaikovskaya, LI Texas A&M Univ Dept Phys College Stn TX 77843 USA Byelarussian Acad Sci BI Stepanov Phys Inst Minsk 220072 BELARUS

For single scattering in a turbid medium, the Mueller matrix is the 4 x 4 matrix that multiplies the incident Stokes vector to yield the scattered Stokes vector. This matrix contains all the information that can be obtained from an elastic-scattering system. We have extended this concept to the multiple-scattering domain where we can define an effective Mueller matrix that, when operating on any incident state of light, will yield the output state. We have calculated this matrix using two completely different computational methods and compared the results for several simple two-layer turbid systems separated by a dielectric interface. We have shown that both methods give reliable results and therefore can be used to accurately predict the scattering properties of turbid media. (C) 2001 Optical Society of America OCIS codes: 290.4210, 030.5620, 290.7050.

关键词： computation methods Mueller matrices Multiple scattering Polarization scattering Scattering media Turbid media

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Approximate Fourier phase information in the phase retrieval problem: what it gives and how to use it

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2011年第10期28卷 2124-2131页

作者： Osherovich, Eliyahu Zibulevsky, Michael Yavneh, Irad Technion Israel Inst Technol Dept Comp Sci IL-32000 Haifa Israel

This work evaluates the importance of approximate Fourier phase information in the phase retrieval problem. The main discovery is that a rough phase estimate (up to pi/2 rad) allows development of very efficient algorithms whose reconstruction time is an order of magnitude faster than that of the current method of choice-the hybrid input-output (HIO) algorithm. Moreover, a heuristic explanation is provided of why continuous optimization methods like gradient descent or Newton-type algorithms fail when applied to the phase retrieval problem and how the approximate phase information can remedy this situation. Numerical simulations are presented to demonstrate the validity of our analysis and success of our reconstruction method even in cases where the HIO algorithm fails, namely, complex-valued signals without tight support information. (C) 2011 Optical Society of America

关键词： computation methods Fourier transforms Numerical simulation Phase estimation Phase retrieval Reconstruction algorithms

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Accurate compressed look up table method for CGH in 3D holographic display

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OPTICS EXPRESS 2015年第26期23卷 33194-33204页

作者： Gao, Chuan Liu, Juan Li, Xin Xue, Gaolei Jia, Jia Wang, Yongtian Beijing Inst Technol Sch Optoelect Beijing Engn Res Ctr Mixed Real & Adv Display Beijing 100081 Peoples R China

Computer generated hologram (CGH) should be obtained with high accuracy and high speed in 3D holographic display, and most researches focus on the high speed. In this paper, a simple and effective computation method for CGH is proposed based on Fresnel diffraction theory and look up table. Numerical simulations and optical experiments are performed to demonstrate its feasibility. The proposed method can obtain more accurate reconstructed images with lower memory usage compared with split look up table method and compressed look up table method without sacrificing the computational speed in holograms generation, so it is called accurate compressed look up table method (AC-LUT). It is believed that AC-LUT method is an effective method to calculate the CGH of 3D objects for real-time 3D holographic display where the huge information data is required, and it could provide fast and accurate digital transmission in various dynamic optical fields in the future. (C) 2015 Optical Society of America

关键词： computation methods Diffraction theory Fresnel diffraction Holographic displays Image quality Optical fields

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Acceleration method of computing a compensated phase-added stereogram on a graphic processing unit

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APPLIED OPTICS 2008年第31期47卷 5784-5789页

作者： Kang, Hoonjong Yamaguchi, Takeshi Yoshikawa, Hiroshi Kim, Seung-Cheol Kim, Eun-Soo Nihon Univ Dept Elect & Comp Sci Chiba 2748501 Japan Kwangwoon Univ Dept Elect Engn 3D Display Res Ctr Seoul 139701 South Korea

We have implemented experimental code to compute a compensated phase-added stereogram (CPAS), which was proposed in a previous paper, on a graphic processing unit (GPU). In this paper, we show an acceleration method for CPAS computation by means of the GPU and compare the computation time between CPU-based and GPU-based calculations, which are programmed ill Our laboratories. In addition, we demonstrate their reconstructed images. As a result, we could achieve a performance gain of a factor of over 33 compared with a CPU-based computing environment and digital holograms can be displayed at 30 frames per second with 15,000 points. (C) 2008 Optical Society of America

关键词： computation methods Fast Fourier transforms Fresnel diffraction Image quality Image resolution Spatial frequency

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3DM: deep decomposition and deconvolution microscopy for rapid neural activity imaging

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OPTICS EXPRESS 2021年第20期29卷 32700-32711页

作者： Cho, Eun-Seo Han, Seungjae Lee, Kang-Han Kim, Cheol-Hee Yoon, Young-Gyu Korea Adv Inst Sci & Technol Sch Elect Engn Daejeon South Korea Chungnam Natl Univ Dept Biol Daejeon South Korea KAIST Inst Hlth Sci & Technol Daejeon South Korea

We report the development of deep decomposition and deconvolution microscopy (3DM), a computational microscopy method for the volumetric imaging of neural activity. 3DM overcomes the major challenge of deconvolution microscopy, the ill-posed inverse problem. We take advantage of the temporal sparsity of neural activity to reformulate and solve the inverse problem using two neural networks which perform sparse decomposition and deconvolution. We demonstrate the capability of 3DM via in vivo imaging of the neural activity of a whole larval zebrafish brain with a field of view of 1040 mu m x 400 mu m x 235 mu m and with estimated lateral and axial resolutions of 1.7 mu m and 5.4 mu m, respectively, at imaging rates of up to 4.2 volumes per second. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： computation methods Image quality Imaging techniques In vivo imaging Inverse problems Three dimensional imaging

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