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Broadband field-of-view expansion using a pair of digital micromirror devices

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2019年第10期36卷 1631-1641页

作者： Dahan, Daniel Yaacobi, Ami Aharonovich, Gil Pinsky, Ephraim Zalevsky, Zeev Bar Ilan Univ Fac Engn IL-5290002 Ramat Gan Israel RAFAEL Electro Opt Dept POB 225039 IL-3102102 Haifa Israel

Broadband field-of-view expansion using computational optics methods is presented. A pair of chirp gratings, implemented by digital micromirror devices, is placed on the optical entrance pupil plane of an optical system. The gratings perform achromatic translations of the image across the camera, and a wide image is reconstructed by a post-processing procedure. Optical design for such a system is proposed, and physical analysis shows the considerations of using these optical elements. All methods are established by simulations and experiments. (C) 2019 Optical Society of America

关键词： Diffraction gratings Digital micromirror devices image processing algorithms Optical design Optical elements Optical systems

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Determination of the Quality Parameters of Higher-Order Bessel Light Beams

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JOURNAL OF APPLIED SPECTROSCOPY 2021年第5期88卷 1020-1034页

作者： Ryzhevich, A. A. Balykin, I. V. Zheleznyakova, T. A. Natl Acad Sci Belarus BI Stepanov Inst Phys Minsk BELARUS Belarusian State Univ Minsk BELARUS

A method is proposed for evaluating the quality of higher-order Bessel light beams (BLBn, order n > 0) by analyzing digital computer images of two-dimensional transverse intensity distributions. One image is sufficient to assess the quality in a specific transverse cross section of a BLBn. algorithms are described which ensure correct implementation of this method: an algorithm for evaluating the position of the axis of an annular beam based on cluster analysis, an algorithm for estimating an initial approximation of the conicity parameter when approximating experimental diametral intensity distributions by the square of a Bessel function based on analyzing the spectral power density of the diametral distribution. The proposed method and algorithms are implemented in the form of an extension of a software package for analyzing the quality of Bessel light beams. The software package is used to test the method experimentally to analyze a BLB1 produced with the aid of KTP (KTiOPO4) and KGW (KGd(WO4)(2)) crystals from a study of a semiconductor laser module (SCLM) and a helium-neon laser (HNL). It is shown that the beam formed by the HNL retains a constant radius along different azimuthal directions while the conformity to the shape of an ideal BLB1 is lost over a larger distance from the axicon than the SCLM, but also loses its constant intensity more rapidly along different azimuthal directions in the first annulus.

关键词： Bessel light beam quality parameters of light beams analysis of transverse intensity distributions image processing algorithms

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Improved autofocus method for human red blood cell images

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APPLIED OPTICS 2019年第29期58卷 8031-8038页

作者： Zhong, Bowen Zhang, Yuxuan Hu, Junjie Jin, Ziqi Wang, Zhenhua Sun, Lining Soochow Univ Coll Mech & Elect Engn Suzhou 215000 Peoples R China

This paper presents an improved autofocus method for human red blood cell images in a microscope. The products of the sum modulus difference and the real-valued fast Fourier transform function are multiplied to obtain an improved sharpness evaluation using the properties of a Gaussian function. It is superior to traditional evaluations in terms of unimodality, steepness, and sensitivity. A new quantitative criterion is proposed to represent the ability of sharpness evaluation against noise. An adaptive focus window with great robustness is proposed that can reduce the computation cost and adverse effects of the background. The better performances of the proposed algorithms are all proved by experiment results, and they can help to find the quasi-focus position more quickly and accurately. (C) 2019 Optical Society of America

关键词： Bandpass filters CMOS cameras Fast Fourier transforms image metrics image processing algorithms Wavelet transforms

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Single-photon three-dimensional imaging at up to 10 kilometers range

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OPTICS EXPRESS 2017年第10期25卷 11919-11931页

作者： Pawlikowska, Agata M. Halimi, Abderrahim Lamb, Robert A. Buller, Gerald S. Leonardo MW Ltd Crewe Rd North Edinburgh EH5 2XS Midlothian Scotland Heriot Watt Univ Sch Engn & Phys Sci Inst Photon & Quantum Sci Edinburgh EH14 4AS Midlothian Scotland

Depth and intensity profiling of targets at a range of up to 10 km is demonstrated using time-of-flight time-correlated single-photon counting technique. The system comprised a pulsed laser source at 1550 nm wavelength, a monostatic scanning transceiver and a singleelement InGaAs/InP single-photon avalanche diode (SPAD) detector. High-resolution three-dimensional images of various targets acquired over ranges between 800 metres and 10.5 km demonstrate long-range depth and intensity profiling, feature extraction and the potential for target recognition. Using a total variation restoration optimization algorithm, the acquisition time necessary for each pixel could be reduced by at least a factor of ten compared to a pixel-wise image processing approach. Kilometer range depth profiles are reconstructed with average signal returns of less than one photon per pixel. (C) 2017 Optical Society of America

关键词： High power lasers image processing image processing algorithms image quality Optical components Optical testing

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image-based method for the angular vibration measurement of a linear array camera

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APPLIED OPTICS 2021年第4期60卷 1003-1012页

作者： Xue Zhi-Peng Wang Chao Li Ming Wang Chunxue Jia Hongguang Yu Yue Chang Guang Satellite Technol Co 1299 Mingxi Rd Changchun 130102 Peoples R China Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys 3888 Dong Nanhu Rd Changchun 130033 Peoples R China Univ Chinese Acad Sci 19 A Yuquan Rd Beijing 100049 Peoples R China

Measurements of angular vibration of aerial cameras in a variety of operating conditions are critical to analyze the performance of the vibration isolation system. Instead of using an additional optical system to measure the angular motion of the camera, an image-based and easy-to-implement method is proposed for the linear array camera to measure the image motions captured by the camera directly. The natural frequencies of the vibration isolation were also measured by laboratory vibration test. For image vibration measuring, the angular vibration is represented in image motion by the relationship between the image motion and angular motion of the camera. Based on the push-broom imaging principle, the image motion at the edge of the foreground image of the linear object is extracted using image processing technology including image segment and edge detection methods. Then the image motion is analyzed in the time and frequency domains. The proposed method has been successfully demonstrated for the angular vibration measurement by a flight test. The results of the vibration sensors and the position and orientation system of the flight tests are also given to validate the effectiveness and accuracy of the proposed approach. (C) 2021 Optical Society of America

关键词： CCD cameras image processing image processing algorithms image quality Position sensing Position sensing equipment

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Simulations of fluorescence imaging in the oral cavity

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BIOMEDICAL OPTICS EXPRESS 2021年第7期12卷 4276-4292页

作者： Lyu, Zheng Jiang, Haomiao Xiao, Feng Rong, Jian Zhang, Tingcheng Wandell, Brian Farrell, Joyce Stanford Ctr Image Syst Engn Stanford CA 94305 USA Dept Elect Engn Stanford CA 94305 USA Facebook AR VR Menlo Pk CA 94025 USA Fengyun Vis Technol Beijing 100080 Peoples R China Psychol Dept Stanford CA 94305 USA

We describe an end-to-end image systems simulation that models a device capable of measuring fluorescence in the oral cavity. Our software includes a 3D model of the oral cavity and excitation-emission matrices of endogenous fluorophores that predict the spectral radiance of oral mucosal tissue. The predicted radiance is transformed by a model of the optics and image sensor to generate expected sensor image values. We compare simulated and real camera data from tongues in healthy individuals and show that the camera sensor chromaticity values can be used to quantify the fluorescence from porphyrins relative to the bulk fluorescence from multiple fluorophores (elastin, NADH, FAD, and collagen). Validation of the simulations supports the use of soft-prototyping in guiding system design for fluorescence imaging. (c) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing image processing algorithms image sensors Imaging systems Systems design Underwater imaging

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Deringing and denoising in extremely under-sampled Fourier single pixel imaging

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OPTICS EXPRESS 2020年第5期28卷 7360-7374页

作者： Rizvi, Saad Cao, Jie Zhang, Kaiyu Hao, Qun Beijing Inst Technol Sch Opt & Photon Key Lab Biomimet Robots & Syst Minist Educ Beijing 100081 Peoples R China

Undersampling in Fourier single pixel imaging (FSI) is often employed to reduce imaging time for real-time applications. However, the undersampled reconstruction contains ringing artifacts (Gibbs phenomenon) that occur because the high-frequency target information is not recorded. Furthermore, by employing 3-step FSI strategy (reduced measurements with low noise suppression) with a low-grade sensor (i.e., photodiode), this ringing is coupled with noise to produce unwanted artifacts, lowering image quality. To improve the imaging quality of real-time FSI, a fast image reconstruction framework based on deep convolutional autoencoder network (DCAN) is proposed. The network through context learning over FSI artifacts is capable of deringing, denoising, and recovering details in 256 x 256 images. The promising experimental results show that the proposed deep-learning-based FSI outperforms conventional FSI in terms of image quality even at very low sampling rates (1-4%). (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Digital micromirror devices image metrics image processing image processing algorithms image quality image reconstruction

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Automatic detection method for BGA defects based on x-ray imaging

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APPLIED OPTICS 2022年第21期61卷 6356-6365页

作者： Xiao, Kai Li, Qin Chen, Yang Natl Univ Def Technol Coll Comp Sci & Technol State Key Lab High Performance Comp Changsha 410073 Peoples R China Natl Key Lab Sci & Technol Blind Signal Proc Chengdu 610000 Peoples R China

Ball grid array (BGA) packaging is a high-density surface mount technology with the advantages of small size, good heat dissipation, and electrical properties, and is widely applied in the production of large-scale integrated circuits. With the rapid development of IC integration, devices assembled using BGA technology generally have greater complexity. However, BGA defects can seriously affect device performance and bring difficulties to product quality inspection. More importantly, in the process of BGA defect inspection, the high complexity of the device brings unprecedented challenges to the precise location of defects, which means that corresponding inspection methods should be improved. To this end, this paper proposes an automatic detection method for BGA defects based on x-ray imaging. First, x-ray imaging technology is utilized to achieve non-destructive detection of the BGA area inside the device and generate image data. On this basis, a set of algorithms including threshold separation, detection filling, and closing operation is designed to complete automatic detection of BGA defects. Furthermore, to objectively evaluate the effectiveness and performance of the proposed method, we conduct a series of comparative experiments using simulated and real data, and generate visual outputs. Through these experiments and analyses, we confirm that the proposed method plays an active and effective role and has robust performance in BCA defect detection. In particular, our method shows the expected performance in precisely finding BGA edge defects and subtle defects. (C) 2022 Optica Publishing Group

关键词： Attenuation coefficient Computed tomography Edge detection image processing image processing algorithms X ray imaging

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Exposure-fusion-based dot-grid image acquisition and recognition for sheet metal strain analysis

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APPLIED OPTICS 2017年第35期56卷 9706-9715页

作者： Shi, Bao-Quan Zhang, Li-Kun Yao, Chen-Song Du, Shu-Xing Ye, JunJie Xidian Univ Minist Educ Key Lab Elect Equipment Struct Design Xian 710071 Shaanxi Peoples R China

Dot-grid images are usually captured for grid strain analysis during sheet metal forming. Due to the strong reflective characteristic of the metallic surfaces, the recorded dot-grid images often have poor quality, low positioning accuracy, and low recognition rate. Therefore, an exposure-fusion-based dot-grid image acquisition and recognition approach is proposed. First, multiple dot-grid images are captured at different exposure levels. Subsequently, the recorded multi-exposure dot-grid images are fused into a new high-quality dot-grid image based on exposure fusion technology. Finally, a dot-grid image recognition procedure is developed to detect the dot-grids in the new dot-grid image. Both synthetic and real dot-grid images were tested to verify the performance of the novel approach. When synthetic dot-grid images were tested, the maximum positioning error was up to 6.044 pixels if they were recognized in the traditional way, whereas the maximum positioning error was reduced to 0.132 pixels if the novel approach was adopted. When real dot-grid images were tested, the lowest recognition rate is only 50.52% if they were recognized in the traditional way. Nevertheless, the recognition rate can reach about 91% if the novel approach was employed. These experimental results show the superiorities of the novel approach. (C) 2017 Optical Society of America

关键词： Digital image processing Edge detection image processing algorithms Optical measurement Speckle patterns Strain measurement

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Partially light-controlled imaging system based on High Temperature Poly-Silicon Thin Film Transistor-Liquid Crystal Display

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OPTICS EXPRESS 2010年第10期18卷 10616-10626页

作者： Tang, Yuanhe Zhang, Ruixia Gao, Haiyang Liu, Kai Zhao, Gaoxiang Yang, Xusan Li, Qing Liang, Yuan Ye, Na Liu, Hanchen Liu, Shulin Xian Univ Technol Sch Sci Xian 710048 Peoples R China Xian Polytech Univ Sch Sci Xian 710048 Peoples R China N Night Vis Technol Co LTD Xian Branch Xian 710065 Peoples R China

A partially light-controlled imaging system is proposed as a novel device. It is used to improve the imaging quality at the illumination of 1.979 x 10(5)lx by means of mitigating image contrast. It consists of a High Temperature Poly-Silicon Thin Film Transistor-Liquid Crystal Display (HTPS TFT-LCD), which is set between the lens and CCD and is coupled with CCD by the optical fiber taper. The transmittance of pixelated LCD can be controlled by Field-Programmable Gate Array to realize the partially light-controlled and thus dynamic range of the imaging system can be extended. Samples of indoor objects and outdoor license plate are photographed by the prototype imaging system under strong light. The imaging results of this novel system are satisfactory with better restored details, compared with the photos taken by normal CCD camera (WAT-231S2) which uses aperture and shutter to control the overall light intensity. (C) 2010 Optical Society of America

关键词： image processing image processing algorithms Light intensity Liquid crystal devices Nematic liquid crystals Thin films

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