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Optimal focal length search and design of a compact zoom lens based on a telecentric intermediate image

APPLIED OPTICS 2022年第25期61卷 7366-7372页

作者： Liu, Yunpeng Yang, Bo Zhuang, Songlin Univ Shanghai Sci & Technol Shanghai Key Lab Modern Opt Syst Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Engn Res Ctr Opt Instrument & Syst Minist Educ Shanghai 200093 Peoples R China

The design of a compact zoom lens requires a designer's most abundant and professional skills and experience, which increases the difficulty of zoom lens miniaturization. In this paper, an automatic optimal focal length search method for a catadioptric zoom lens is proposed. After 7 h of searching for the initial structure and further optimization, a 3 x compact zoom lens based on a telecentric intermediate image is obtained, which is applicable for 1/4 inch (6.35 mm) CMOS, with a focal length range of 4.8 similar to 14 mm and a F-number range of 2.7-8.0. The depth and total length are within 6 mm and 30 mm, separately. The proposed method helps to reduce researchers' difficulty in designing compact zoom lenses and can provide some reference for the development of the mobile zoom lens industry. (c) 2022 Optica Publishing Group

关键词： image processing image processing algorithms Lens design Optical design Optical design software Zoom lenses

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Laser induced ultrasonic phased array using full matrix capture data acquisition and total focusing method

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OPTICS EXPRESS 2016年第19期24卷 21921-21938页

作者： Stratoudaki, Theodosia Clark, Matt Wilcox, Paul D. Univ Bristol Dept Mech Engn Bristol BS8 1TR Avon England Univ Nottingham Fac Engn Div Elect Syst & Opt Univ Pk Nottingham NG7 2RD England

Laser ultrasonics is a technique where lasers are employed to generate and detect ultrasound. A data collection method (full matrix capture) and a post processing imaging algorithm, the total focusing method, both developed for ultrasonic arrays, are modified and used in order to enhance the capabilities of laser ultrasonics for nondestructive testing by improving defect detectability and increasing spatial resolution. In this way, a laser induced ultrasonic phased array is synthesized. A model is developed and compared with experimental results from aluminum samples with side drilled holes and slots at depths of 5 - 20 mm from the surface. (C) 2016 Optical Society of America

关键词： High power lasers image processing algorithms image quality Laser arrays Laser sources Phased arrays

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CTF determination and correction in electron cryotomography

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ULTRAMICROSCOPY 2006年第7期106卷 587-596页

作者： Fernandez, J. J. Li, S. Crowther, R. A. Univ Almeria Dept Comp Architecture & Elect Almeria 04120 Spain MRC Mol Biol Lab Cambridge CB2 2QH England

Electron cryotomography (cryoET) has the potential to elucidate the structure of complex biological specimens at molecular resolution but technical and computational improvements are still needed. This work addresses the determination and correction of the contrast transfer function (CTF) of the electron microscope in cryoET. Our approach to CTF detection and defocus determination depends on strip-based periodogram averaging, extended throughout the tilt series to overcome the low contrast conditions found in cryoET. A method for CTF correction that deals with the defocus gradient in images of tilted specimens is also proposed. These approaches to CTF determination and correction have been applied here to several examples of cryoET of pleomorphic specimens and of single particles. CTF correction is essential for improving the resolution, particularly in those studies that combine cryoET with single particle averaging techniques. (c) 2006 Elsevier B.V. All rights reserved.

关键词： contrast transfer function CTF electron cryotomography image processing algorithms image reconstruction

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Color three-dimensional imaging based on patterned illumination using a negative pinhole array

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OPTICS EXPRESS 2021年第5期29卷 6509-6522页

作者： Kim, Chang-Soo Kim, Junyoung Yoo, Hongki Korea Res Inst Stand & Sci KRISS Adv Instrumentat Inst Opt Imaging & Metrol Team Sci Town 34113 Daejeon South Korea Harvard Med Sch Wellman Ctr Photomed 55 Fruit St Boston MA 02114 USA Massachusetts Gen Hosp 55 Fruit St Boston MA 02114 USA Korea Adv Inst Sci & Technol Dept Mech Engn 291 Daehak Ro Daejeon 34141 South Korea

Reflectance confocal microscopy is widely used for non-destructive optical three-dimensional (3D) imaging. In confocal microscopy, a stack of sequential two-dimensional (2D) images with respect to the axial position is typically needed to reconstruct a 3D image. As a result, in conventional confocal microscopy, acquisition speed is often limited by the rate of mechanical scanning in both the transverse and axial directions. We previously reported a high-speed parallel confocal detection method using a pinhole array for color 3D imaging without any mechanical scanners. Here, we report a high-speed color 3D imaging method based on patterned illumination employing a negative pinhole array, whose optical characteristics are the reverse of the conventional pinhole array for transmitting light. The negative pinhole array solves the inherent limitation of a conventional pinhole array, i.e., low transmittance, meaning brighter color images with abundant color information can be acquired. We also propose a 3D image processing algorithm based on the 2D cross-correlation between the acquired image and filtering masks, to produce an axial response. By using four-different filtering masks, we were able to increase the sampling points in calculation of height and enhance the lateral resolution of the color acquisition by a factor of four. The feasibility of high-speed non-contact color 3D measurement with the improved lateral resolution and brightness provided by the negative pinhole array was demonstrated by imaging various specimens. We anticipate that this high-speed color 3D measurement technology with negative pinhole array will be a useful tool in a variety of fields where rapid and accurate non-contact measurement are required, such as industrial inspection and dental scanning. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Brightness Confocal microscopy image processing algorithms Spatial light modulators Three dimensional image processing Three dimensional imaging

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Improving the visible light communication localization system using Kalman filtering with averaging

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2020年第11期37卷 A130-A138页

作者： Shawky, Eman El-Shimy, Mohamed Mokhtar, Amr El-Badawy, El-Sayed A. Shalaby, Hossam M. H. Alexandria Univ Fac Engn Elect Engn Dept Alexandria 21544 Egypt Egypt Japan Univ Sci & Technol E JUST Dept Elect & Commun Engn Alexandria 21934 Egypt

Two techniques are proposed for improving the accuracy of localization estimation in indoor visible light communication systems, namely, averaging and Kalman filtering with averaging schemes. In the averaging technique, the receiver position is estimated using the received signal strength (RSS) indication method multiple times (e.g., N samples), and the acquired estimations are averaged over all samples. To further improve the localization, the Kalman filtering algorithm is adopted to estimate the received power over N samples, followed by applying the RSS technique on the average received power. The proposed techniques are analyzed mathematically, considering the effects of both line-of-sight (LOS) and first-reflection from non-LOS propagations. The performance of the proposed techniques is determined by evaluating the positioning errors in a typical room. The results are compared to that of the traditional RSS system. Simulation results reveal that an improvement of about 33.3% in the average positioning error is achievable when using the averaging scheme as compared to that of the traditional RSS scheme. This improvement increases to 72.2% when adopting the proposed Kalman filtering scheme. (C) 2020 Optical Society of America

关键词： image processing algorithms Optical signals Optical wireless communication Phase measurement Visible light Visible light communications

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Turbulence-induced edge image waviness: theory and experiment

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APPLIED OPTICS 2001年第9期40卷 1321-1328页

作者： Belen'kii, MS Stewart, JM Gillespie, P Georgia Inst Technol Atlanta GA 30332 USA USA Res Lab Battlefield Environm Directorate Adelphi MD 20783 USA

A theoretical model for the edge image waviness effect is developed for the ground-to-ground imaging scheme and validated by use of IR imagery data collected at the White Sands Missile Range. It is shown that angle-of-arrival (AA) angular anisoplanatism causes the phenomenon of edge image waviness and that the AA correlation scale, not the isoplanatic angle, characterizes the edge image waviness scale. The latter scale is determined by the angular size of the imager and a normalized atmospheric outer scale, and it does not depend on the strength of turbulence along the path. Spherical divergence of the light waves increases the edge waviness scale. A procedure for estimating the atmospheric and camera-noise components of the edge image motion is developed and implemented. A technique for mitigation of the edge image waviness that relies on averaging the effects of AA anisoplanatism on the image is presented and validated. The edge waviness variance is reduced by a factor of 2-3. The time history and temporal power spectrum of the edge image motion are obtained. I These data confirm that the observed edge image motion is caused by turbulence. (C) 2001 Optical Society of America.

关键词： Edge detection image processing algorithms Imaging systems Laser guide stars Machine vision Power spectra

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Ronchi test with equivalent wavelength

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APPLIED OPTICS 2012年第15期51卷 3071-3080页

作者： Garcia-Arellano, Anmi Granados-Agustin, Fermin Campos-Garcia, Manuel Cornejo-Rodriguez, Alejandro Inst Nacl Astrofis Opt & Elect Sta Ma Tonantzintl Dept Opt Puebla 72000 Mexico Univ Nacl Autonoma Mexico Ctr Ciencias Aplicadas & Desarrollo Tecnol Mexico City 04510 DF Mexico

In this work we present an experimental proposal to evaluate optical surfaces with high slopes or with infrared wavelengths based on the Ronchi test as well as on the concept of equivalent wavelength. A spatial modulator is used in the implementation of the Ronchi test, and a white LED with different color filters is employed in order to generate different wavelengths. Two Ronchigrams with incoherent light, each one for a different color, are registered and computationally processed, thus generating a third one with an equivalent wavelength. The results obtained show that it is possible to generate patterns with traditional rulings and substructured sequences of Katyl. Additionally, we discuss some of the limitations of employing different rulings. Finally, we found that appropriate image enhancing algorithms allow us to improve the visibility of the resulting fringes and thus obtain a better analysis. (C) 2012 Optical Society of America

关键词： Digital image processing image processing algorithms Modulators Optical surfaces Ronchi gratings Ronchi tests

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Translational and rotational manipulation of filamentous cells using optically driven microrobots

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OPTICS EXPRESS 2019年第12期27卷 16475-16482页

作者： Hu, Songyu Hu, Ruifeng Dong, Xiaobin Wei, Tanyong Chen, Shuxun Sun, Dong Zhejiang Univ Coll Mech Engn State Key Lab Fluid Power & Mechatron Syst Hangzhou Zhejiang Peoples R China Zhejiang Univ Coll Mech Engn Key Lab 3D Printing Proc & Equipment Zhejiang Pro Hangzhou Zhejiang Peoples R China Univ Pittsburgh Dept Mech Engn & Mat Sci Pittsburgh PA 15260 USA Shenzhen Univ Coll Mechatron & Control Engn Shenzhen Peoples R China City Univ Hong Kong Dept Biomed Engn Hong Kong Peoples R China

Optical cell manipulation has become increasingly valuable in cell-based assays. In this paper, we demonstrate the translational and rotational manipulation of filamentous cells using multiple cooperative microrobots automatically driven by holographic optical tweezers. The photodamage of the cells due to direct irradiation of the laser beam can be effectively avoided. The proposed method will enable fruitful biomedical applications where precise cell manipulation and less photodamage are required. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Femtosecond fiber lasers High numerical aperture optics image processing algorithms Laser beams Optical trapping Optical tweezers

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Adaptive convergence nonuniformity correction algorithm

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APPLIED OPTICS 2011年第1期50卷 1-10页

作者： Qian, Weixian Chen, Qian Bai, Junqi Gu, Guohua Nanjing Univ Sci & Technol EEOT JGMT Lab 440 Nanjing 210094 Jiangsu Prov Peoples R China

Nowadays, convergence and ghosting artifacts are common problems in scene-based nonuniformity correction (NUC) algorithms. In this study, we introduce the idea of space frequency to the scene-based NUC. Then the convergence speed factor is presented, which can adaptively change the convergence speed by a change of the scene dynamic range. In fact, the convergence speed factor role is to decrease the statistical data standard deviation. The nonuniformity space relativity characteristic was summarized by plenty of experimental statistical data. The space relativity characteristic was used to correct the convergence speed factor, which can make it more stable. Finally, real and simulated infrared image sequences were applied to demonstrate the positive effect of our algorithm. (C) 2010 Optical Society of America

关键词： algorithms image processing image processing algorithms Infrared imaging Motion estimation Wavelet transforms

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Robust optical axis control of monocular active gazing based on pan-tilt mirrors for high dynamic targets

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OPTICS EXPRESS 2021年第24期29卷 40214-40230页

作者： Cao, Ruimin Fu, Jian Yang, Hui Wang, Lihui Ishikawa, Masatoshi Guangdong Acad Sci Inst Semicond Guangzhou 510650 Peoples R China Univ Tokyo Informat Technol Ctr Data Sci Res Div Tokyo 1138656 Japan

The real-time and stability performance are both crucial for the active vision system (AVS) to gaze the high dynamic targets (HDTs). This study focused on the robust optical axis control mechanism of monocular AVS based on pan-tilt mirrors. We proposed an adaptive selfwindow to accommodate the HDTs within the region of interest. The minimum-envelope-ellipse and unscented-Kalman-filter methods were proposed to compensate and predict the angle of optical axis when the HDTs were blocked. The static and dynamic compensation error rates were less than 1.46% and 2.71%, prediction error rate was less than 13.88%, improving the gazing stability while ensuring real-time performance. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： High speed photography image processing image processing algorithms Liquid lenses Optical design Parallel processing

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