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Fast computation method for a Fresnel hologram using three-dimensional affine transformations in real space

APPLIED OPTICS 2009年第34期48卷 H212-H221页

作者： Sakata, Hironobu Sakamoto, Yuji Hokkaido Univ Grad Sch Informat Sci & Technol Kita Ku Sapporo Hokkaido 0600814 Japan

Calculating computer-generated holograms takes a tremendous amount of computation time. We propose a fast method for calculating object lights for Fresnel holograms without the use of a Fourier transform. This method generates object lights of variously shaped patches from a basic object light for a fixed-shape patch by using three-dimensional affine transforms. It can thus calculate holograms that display complex objects including patches of various shapes. Computer simulations and optical experiments demonstrate the effectiveness of this method. The results show that it performs twice as fast as a method that uses a Fourier transform. (C) 2009 Optical Society of America

关键词： computation methods Far field diffraction Fourier transforms Fresnel diffraction Red light emitting diodes Wave propagation

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Cadillac Desert: The American West and Its Disappearing Water

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JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 2009年第6期45卷 1379-1389页

作者： Altaweel, Mark R. Alessa, Lilian N. Kliskey, Andrew D. Univ Alaska Anchorage Resilience & Adapt Management Grp Anchorage AK 99508 USA Argonne Natl Lab Argonne IL 60439 USA Univ Chicago Computat Inst Chicago IL 60637 USA

Arctic communities are increasingly faced with social-ecological changes that act at variable speeds and spatial scales. Such changes will affect vital resources, particularly water supplies. Currently, there are few computational tools that integrate multiple social and environmental processes in order to aid communities' adaptation to change through decision support systems. This paper proposes a modeling and simulation approach that can integrate such processes at different spatiotemporal scales in order to address issues affecting community water supplies. In this paper, a modeling and simulation tool is developed and applied to a case study on the Seward Peninsula. Initial results, using both field observations and computation, show projected patterns of water use, perceptions of water availability, and long-term consumption trends. More broadly, the paper demonstrates the need for developing tools that address issues at the community level for better understanding human and hydrological interactions and policy decisions affecting water supplies.

关键词： computation methods modeling municipal water systems nonmunicipal systems social-ecological Arctic agent-based

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Extremely high-definition full-parallax computer-generated hologram created by the polygon-based method

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APPLIED OPTICS 2009年第34期48卷 H54-H63页

作者： Matsushima, Kyoji Nakahara, Sumio Kansai Univ Dept Elect & Elect Engn Osaka 5648680 Japan Kansai Univ Dept Mech Engn Osaka 5648680 Japan

A large-scale full-parallax computer-generated hologram (CGH) with four billion (2(16) x 2(16)) pixels is created to reconstruct a fine true 3D image of a scene, with occlusions. The polygon-based method numerically generates the object field of a surface object, whose shape is provided by a set of vertex data of polygonal facets, while the silhouette method makes it possible to reconstruct the occluded scene. A novel technique using the segmented frame buffer is presented for handling and propagating large wave fields even in the case where the whole wave field cannot be stored in memory. We demonstrate that the full-parallax CGH, calculated by the proposed method and fabricated by a laser lithography system, reconstructs a fine 3D image accompanied by a strong sensation of depth. (C) 2009 Optical Society of America

关键词： computation methods Computer generated holograms Parallel processing Spatial frequency Spatial resolution Three dimensional imaging

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The Infrared Spectral Signatures of Disease: Extracting the Distinguishing Spectral Features Between Normal and Diseased States

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APPLIED SPECTROSCOPY 2009年第11期63卷 307A-318A页

作者： Diem, Max Papamarkakis, Kostas Schubert, Jennifer Bird, Benjamin Romeo, Melissa J. Miljkovic, Milos Northeastern Univ Dept Chem & Chem Biol Boston MA 02115 USA

No abstract available.

关键词： Applied spectroscopy computation methods Infrared imaging Spatial resolution Spectroscopy Tissue

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Subgridding in the finite-difference time-domain method for simulating the interaction of terahertz radiation with metal

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2008年第3期25卷 279-285页

作者： Kern, Andreas Walther, Markus Univ Freiburg Dept Mol & Opt Phys D-79104 Freiburg Germany

Simulating the interaction of electromagnetic terahertz radiation with metals poses difficulties not encountered in the optical regime. Owing to a penetration depth small compared to the wavelength, such simulations in the terahertz frequency range require large discretization volumes with very small grid spacings. We present a unique subgridding scheme that accurately describes this interaction while keeping computational costs minimal. Bidirectional coupling between grids allows for the complete integration of subdomains into the simulation volume. Implementation in one and two dimensions is demonstrated, and a comparison with theoretical and experimental results [Opt. Express 15, 6552 (2007)] [Phys. Rev. B 69, 155427 (2004)] is given. Using our technique, we are able to accurately simulate plasmonic effects in terahertz experiments for the first time. (C) 2008 Optical Society of America.

关键词： computation methods Electric fields Electromagnetic radiation Signal processing Surface plasmons Systems design

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Regularizing active set method for retrieval of the atmospheric aerosol particle size distribution function

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2008年第2期25卷 348-356页

作者： Wang, Yanfei Yang, Changchun Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

The determination of the aerosol particle size distribution function by using the particle spectrum extinction equation is an ill-posed integral equation of the first kind [S. Twomey, J. Comput. Phys. 18, 188 (1975);Y. F. Wang, computational methods for Inverse Problems and Their Applications (Higher Education Press, 2007)], since we are often faced with limited or insufficient observations in remote sensing and the observations are contaminated. To overcome the ill-posed nature of the problem, regularization techniques were developed. However, most of the literature focuses on the application of Phillips-Twomey regularization and its variants, which are unstable in several cases. As is known, the particle size distribution is always nonnegative, and we are often faced with incomplete data. Therefore, we study the active set method and propose a regularizing active set algorithm for ill-posed particle size distribution function retrieval and for enforcing nonnegativity in computation. Our numerical tests are based on synthetic data for theoretical simulations and the field data obtained with a CE 318 Sun photometer for the Po Yang lake region of Jiang Xi Province, China, and are performed to show the efficiency and feasibility of the proposed algorithms. (C) 2008 Optical Society of America.

关键词： computation methods Computed tomography Extinction coefficients Inverse problems Mie theory Remote sensing

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computation theory of partially coherent imaging by stacked pupil shift matrix

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2008年第12期25卷 3111-3119页

作者： Yamazoe, Kenji Canon Inc Utsunomiya Tochigi 3213298 Japan

A theory of partially coherent imaging is presented. In this theory, a singular matrix P is introduced in a spatial frequency domain. The matrix P can be obtained by stacking pupil functions that are shifted according to the illumination condition. Applying singular-value decomposition to the matrix P generates eigenvalues and eigenfunctions. Using eigenvalues and eigenfunctions, the aerial image can be computed without the transmission cross coefficient (TCC). A notable feature of the matrix P is that the relationship between the matrix P and the TCC matrix T isT=P(dagger)P, where dagger represents the Hermitian conjugate. This suggests that the matrix P can be regarded as a fundamental operator in partially coherent imaging. (C) 2008 Optical Society of America

关键词： computation methods Light intensity Matrix methods Pupil Spatial frequency Transmission coefficient

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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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Hologram synthesis for photorealistic reconstruction

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2008年第12期25卷 3083-3096页

作者： Janda, Martin Hanak, Ivo Onural, Levent Univ W Bohemia Dept Comp Sci & Engn Plzen 30614 Czech Republic Bilkent Univ Dept Elect & Elect Engn TR-06800 Ankara Turkey

computation of diffraction patterns, and thus holograms, of scenes with photorealistic properties is a highly complicated and demanding process. An algorithm, based primarily on computer graphics methods, for computing full-parallax diffraction patterns of complicated surfaces with realistic texture and reflectivity properties is proposed and tested. The algorithm is implemented on single-CPU, multiple-CPU and CPU platforms. An alternative algorithm, which implements reduced occlusion diffraction patterns for much faster but somewhat lower quality results, is also developed and tested. The algorithms allow GPU-aided calculations and easy parallelization. Both numerical and optical reconstructions are conducted. The results indicate that the presented algorithms compute diffraction patterns that provide successful photorealistic reconstructions;the computation times are acceptable especially on the GPU implementations. (C) 2008 Optical Society of America

关键词： computation methods Holographic recording Light properties Optical fields Ptychography Spatial frequency

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Resolution-enhanced three-dimensional image reconstruction by use of smart pixel mapping in computational integral imaging

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APPLIED OPTICS 2008年第35期47卷 6656-6665页

作者： Shin, Dong-Hak Tan, Chun-Wei Lee, Byung-Gook Lee, Joon-Jae Kim, Eun-Soo Keimyung Univ Dept Game Mobile Contents Taegu 705701 South Korea Dongseo Univ Dept Visual Contents Pusan 617716 South Korea Kwangwoon Univ Dept Elect Seoul 139701 South Korea

computational integral imaging method can digitally provide a series of plane images of three-dimensional (3D) objects. However, the resolution of 3D reconstructed images is dramatically degraded as the distance from the lenslet array increases. In this paper, to overcome this problem, we propose a novel computational integral imaging reconstruction (CIIR) method based on smart pixel mapping (SPM). Since SPM is a computational process in which elemental images recorded at long distances are convertible to ones recorded near lenslet array, this can give us the improved resolution of plane images for 3D objects located at a long distance range from a lenslet array For the effective use of the SPM-based CIIR method, we design a novel two-stage CIIR method by the combined use of the conventional CIIR and the SPM-based one. The conventional CIIR method is applied over a short distance range, while the SPM-based CIIR is used over a long distance range. We carry out some experiments to verify the performance of the two-stage CIIR system. From the experimental results, the proposed system can provide a substantial gain over a long distance range in terms of the resolution of reconstructed plane images. (c) 2008 Optical Society of America.

关键词： computation methods Image quality Image reconstruction Image sensors Three dimensional imaging Three dimensional reconstruction

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