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Structured light sheet fluorescence microscopy based on four beam interference

OPTICS EXPRESS 2010年第18期18卷 19232-19241页

作者： Lei, Ming Zumbusch, Andreas Univ Konstanz Dept Chem D-78457 Constance Germany Chinese Acad Sci State Key Lab Transient Opt & Photon Xian Inst Opt & Precis Mech Xian 710119 Peoples R China

A 3D structured light sheet microscope using a four-faceted symmetric pyramid is presented. The sample is illuminated by the resulting four beam interference field. This approach combines advantages of standing wave and structured illumination microscopy. Examples of micrographs of fluorescently labeled Chinese hamster ovary (CHO) cells as well as of the compound eyes of drosophila are shown and the optical sectioning ability of our system is demonstrated. The capabilities and the limitations of the scheme are discussed. (C) 2010 Optical Society of America

关键词： Confocal microscopy Fluorescence microscopy image processing algorithms Light sheet microscopy Multiphoton microscopy Structured illumination microscopy

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Analysis and improvement of non-contact SpO2 extraction using an RGB webcam

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BIOMEDICAL OPTICS EXPRESS 2021年第8期12卷 5227-5245页

作者： Wei, Bing Wu, Xiaopei Zhang, Chao Lv, Zhao Anhui Univ Sch Comp Sci & Technol Anhui Prov Key Lab Multimodel Cognit Computat Hefei 230601 Peoples R China Hefei Normal Coll Dept Comp Sci & Technol Hefei 230601 Peoples R China

Peripheral oxygen saturation (SpO2), a vital physiological sign employed in clinical care, is commonly obtained by using a contact pulse oximeter. With the rapid popularization of ordinary red-green-blue (RGB) webcams embedded in devices such as smartphones or laptops, there are broad application prospects for exploring techniques for non-contact SpO2 extraction using RGB webcams. However, many issues remain to be solved in the traditional webcam-based SpO2 extraction methods, such as the inherent low signal-to-noise ratio (SNR) of alternating current (AC) components of RGB signals and the potential defects in using RGB signals combination for SpO2 extraction. In this study, we conducted an in-depth examination of the existing research on webcam-based SpO2 extraction techniques, analyzed the practical problems in using them, and explored new ideas to solve the problems. Rather than roughly using the standard deviations (SD) of AC components for calculations, we performed blind source separation for AC components, and then used the energy coefficients retained in the mixed matrix to replace the variables required in the algorithm. Moreover, steady data was selected to compensate for the potential defects in using RGB signals combination. Through these efforts, the anti-noise capability of the algorithm was significantly enhanced, and the related defects were compensated for. The experimental results indicated that the proposed method produced reliable SpO2 estimation that could potentially-with further research-be used in real applications. (c) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Absorption coefficient CCD cameras image analysis image processing algorithms Infrared radiation Light intensity

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Determination of model airplane attitudes using dynamic holographic interferometry

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APPLIED OPTICS 2008年第21期47卷 3877-3885页

作者： Banerjee, Partha P. Nehmetallah, Georges Kukhtarev, Nickolai Praharaj, Sarat C. Univ Dayton Dept Elect & Comp Engn Dayton OH 45458 USA Alabama A&M Univ Dept Phys Normal AL 35762 USA DMS Technol Inc Huntsville AL 35805 USA

We demonstrate how real-time holographic interferometry yielding two-dimensional fringes can be recorded and used to determine changes in three-dimensional attitude of a model airplane through digital image processing. A simple bench-top experiment with a model airplane as a test object is conducted to demonstrate interference fringes superposed on the image due to changes in attitudes (pitch, yaw, and roll) as well as distortion. A novel second-generation thermoplastic camera suitable for dynamic multiple reversible registration of thin-phase holograms using thermoplastic and semiconductor film on glass substrate is used for in situ recording and readout during real-time holographic interferometry. Thin-phase holograms also offer the advantage of exact image reconstruction from forward-phase conjugation. (C) 2008 Optical Society of America.

关键词： Digital image processing Holographic interferometry Holographic optical elements image processing image processing algorithms image reconstruction

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Procedure for detecting the shape and size of defects on metallic substrates under composite repairs using shearography

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APPLIED OPTICS 2020年第27期59卷 8089-8097页

作者： Felipe, Diego Staub Benedet, Mauro Fantin, Analucia Vieira Willemann, Daniel Pedro Fonseca Martins, Fabiana Dias Fampa Seabra D'Almeida, Ana Lucia Soares, Sergio Damasceno Goncalves Jr, Armando Albertazzi Lenzi, Arcanjo Univ Fed Santa Catarina 5053 Univ Campus Florianopolis SC Brazil Univ Estado Santa Catarina 2007 Itacorubi Florianopolis SC Brazil CENPES Petrobras Rio De Janeiro RJ Brazil

This paper presents a numerical-experimental procedure to characterize through-holes with arbitrary shapes present on metallic substrates under composite material sleeves using pulsed laser shearography and dynamic excitation combined to the finite element method. The so-called fitting process consists of matching experimental and numerical results in order to determine the shape and dimensions of the holes under the composite repair, or even quantify defects between layers of the composite laminate. The results show that the technique is capable of characterizing, in the worst case, the geometry of a hole with 83% accuracy and its respective area with a maximum error of approximately 20%. The advantageous results achieved in this research show that the fitting process can be very useful for real applications in the oil and petroleum industry. (C) 2020 Optical Society of America

关键词： Composite materials image processing algorithms Industrial optical metrology Interferometry Michelson interferometers Pulsed operation

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Automatic classification of aerial imagery

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DEFENCE SCIENCE JOURNAL 2007年第6期57卷 773-786页

作者： Majumdar, Jhama Lekshmi, S. Vanathy, B. ADE Aerial Image Exploitat Div Bangalore Karnataka India

The aerial imagery obtained from reconnaissance platform is voluminous and the defence forces rely on image information to perform intelligent tasks. The application of a well designed automatic image classifier would enhance the end results of different high level applications thereby abridging the effort of a human analyst. Automatic image classifiers could be designed using a training data set for supervised learning or using an unsupervised learning. In this paper, a method, which combines both unsupervised and supervised methods of learning is proposed.

关键词： aerial imagery automatic image classifier image information surveillance image processing algorithms image classification

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Real-time detection method for bulk bubbles in optics based on deep learning

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APPLIED OPTICS 2022年第15期61卷 4344-4353页

作者： Wang, Yue Cheng, Xinglei Qian, Changde Zhang, JianPu Hu, Xiaobo Wang, Hongxia Huang, Menghui Lu, An Sun, Huanyu Wang, Shiling Shen, Zheqiang Wu, Lan Liu, Dong Zhejiang Univ Coll Opt Sci & Engn State Key Lab Modern Opt Instrumentat Hangzhou 310027 Peoples R China Jiaxing Key Lab Photon Sensing & Intelligent Imag Jiaxing 314000 Peoples R China Zhejiang Univ Intelligent Opt & Photon Res Ctr Jiaxing Res Inst Jiaxing 314000 Peoples R China Zhejiang Univ Int Res Ctr Adv Photon Hangzhou 310027 Peoples R China

The existence of bulk bubbles could decrease the laser-induced damage threshold of optics and affect the beam quality, so the detection of bulk bubbles is an essential step for quality assurance. Currently, the inspection of bubbles in optics relies on manual work, which is not recommended because of the low precision and inconsistency. To improve the quality evaluation process, a real-time detection method for bubbles inside the optics based on deep learning is proposed. Our method can implement bubble detection at 67 fps with a recall of 0.836. As for retrieval of the radius, it costs 58.8 ms on each bubble, and the absolute deviation is 3.73% on average. Our method conducts real-time and accurate detection of the positions and radii of the bubbles in the optics, thus, having significant potential for the manufacturing process. (C) 2022 Optica Publishing Group

关键词： High power lasers image processing algorithms Laser damage Laser systems Light fields Mie theory

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image encryption by encoding with a nonuniform optical beam in gyrator transform domains

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APPLIED OPTICS 2010年第29期49卷 5632-5637页

作者： Liu, Zhengjun Xu, Lie Lin, Chuang Liu, Shutian Harbin Inst Technol Dept Automat Measurement & Control Engn Harbin 150001 Peoples R China Harbin Inst Technol Dept Phys Harbin 150001 Peoples R China Dalian Univ Technol Sch Software Dept Network Engn Dalian 116620 Peoples R China

Based on an optical gyrator transform system, an image encryption algorithm is designed and studied. An original secret image is regarded as the output intensity of the second gyrator transform. A coherent nonuniform optical beam is converted into the input of the first gyrator transform. A Gerchberg-Saxton phase retrieval algorithm is employed for obtaining the compensation phases in the first gyrator transform pair. The compensation phases are regarded as the encrypted image and key in this algorithm. The parameters of the laser beam and gyrator transform can serve as the additional key of encryption method. The decryption process of this encryption algorithm can be achieved with an optical system. Numerical simulations are performed to test the validity and capability of the encryption algorithm. (C) 2010 Optical Society of America

关键词： Fractional Fourier transforms image encryption image processing algorithms Laser beams Phase retrieval Stochastic processes

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Laser light source limited uncertainty of speckle-based roughness measurements

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APPLIED OPTICS 2019年第23期58卷 6436-6445页

作者： Patzelt, Stefan Stoebener, Dirk Fischer, Andreas Univ Bremen Bremen Inst Metrol Automat & Qual Sci Linzer Str 13 D-28359 Bremen Germany Univ Bremen Inst Technol & Educ Hochschulring 20 D-28359 Bremen Germany Univ Bremen MAPEX Ctr Mat & Proc Bremen Germany

Surface microtopography measurement (e.g., form, waviness, roughness) is a precondition to assess the surface quality of technical components with regard to their applications. Laser speckle-based roughness measurement is an optical scattered light measuring technique that provides field of view dimensions of some square millimeters and measuring frequencies in the kilohertz domain enabling in-process roughness characterization of even moving part surfaces. However, camera exposure times of microseconds or less and a high detector pixel density mean less light energy per pixel. This affects the minimal achievable measurement uncertainty, which has not been clarified yet for almost plain sample shapes. For this reason, the measurement uncertainty limit of the surface roughness parameter Sa due to fundamental, inevitable noise sources such as laser shot noise and detector noise is analytically estimated and compared to experimental data. The results show a mainly shot-noise-limited measurement uncertainty contribution of less than 0.033 nm. In addition, a significant influence of laser beam profile variations on the achievable roughness measurement uncertainty is identified for the current experimental setup, which is generally below 0.3 nm and can be improved in future setups. The already achieved low measurement uncertainty offers ideal preconditions for in-process roughness measurements on samples with a similar surface structure in industrial environments. (C) 2019 Optical Society of America

关键词： Atomic force microscopy CCD cameras High power diode lasers image processing algorithms Laser sources Speckle patterns

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Ultrathin arrayed camera for high-contrast near-infrared imaging

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OPTICS EXPRESS 2021年第2期29卷 1333-1339页

作者： Kim, Kisoo Jang, Kyung-Won Bae, Sang-In Kim, Hyun-Kyung Cha, Younggil Ryu, Jae-Kwan Jo, Yong-Jin Jeong, Ki-Hun Dept Bio & Brain Engn 291 Daehak Ro Daejeon 34141 South Korea KAIST Inst Hlth Sci & Technol 291 Daehak Ro Daejeon 34141 South Korea Korea Adv Inst Sci & Technol KAIST 291 Daehak Ro Daejeon 34141 South Korea LIG Nexl Co Ltd Unmanned Robot Syst Lab Seongnam 13488 South Korea

We report an ultrathin arrayed camera (UAC) for high-contrast near infrared (NIR) imaging by using microlens arrays with a multilayered light absorber. The UAC consists of a multilayered composite light absorber, inverted microlenses, gap-alumina spacers and a planar CMOS image sensor. The multilayered light absorber was fabricated through lift-off and repeated photolithography processes. The experimental results demonstrate that the image contrast is increased by 4.48 times and the MTF 50 is increased by 2.03 times by eliminating optical noise between microlenses through the light absorber. The NIR imaging of UAC successfully allows distinguishing the security strip of authentic bill and the blood vessel of finger. The ultrathin camera offers a new route for diverse applications in biometric, surveillance, and biomedical imaging. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing algorithms image quality Imaging systems Medical imaging Microlens arrays Scanning electron microscopy

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Principal-vector-directed fringe-tracking technique

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APPLIED OPTICS 2014年第31期53卷 7381-7393页

作者： Zhang, Zhihui Guo, Hongwei Shanghai Univ Dept Precis Mech Engn Lab Appl Opt & Metrol Shanghai 200072 Peoples R China

Fringe tracking is one of the most straightforward techniques for analyzing a single fringe pattern. This work presents a principal-vector-directed fringe-tracking technique. It uses Gaussian derivatives for estimating fringe gradients and uses hysteresis thresholding for segmenting singular points, thus improving the principal component analysis method. Using it allows us to estimate the principal vectors of fringes from a pattern with high noise. The fringe-tracking procedure is directed by these principal vectors, so that erroneous results induced by noise and other error-inducing factors are avoided. At the same time, the singular point regions of the fringe pattern are identified automatically. Using them allows us to determine paths through which the "seed" point for each fringe skeleton is easy to find, thus alleviating the computational burden in processing the fringe pattern. The results of a numerical simulation and experiment demonstrate this method to be valid. (C) 2014 Optical Society of America

关键词： Analytical techniques Digital image processing Fourier transforms Fringe analysis image processing algorithms Numerical simulation

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