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Hilbert phase microscopy based on pseudo thermal illumination in the Linnik configuration

OPTICS LETTERS 2022年第22期47卷 5793-5796页

作者： Rogalski, Mikolaj Cywinska, Maria Ahmad, Azeem Patorski, Krzysztof Mico, Vicente Ahluwalia, Balpreet S. Trusiak, Maciej Warsaw Univ Technol Inst Micromech & Photon 8 Sw A Boboli St PL-02525 Warsaw Poland UiT Arctic Univ Norway Dept Phys & Technol NO-9037 Tromso Norway Univ Valencia Dept Opt & Optometria & Ciencias Vis C Doctor Moliner 50 E-46100 Burjassot Spain

Quantitative phase microscopy (QPM) is often based on recording an object-reference interference pattern and its further phase demodulation. We propose pseudo Hilbert phase microscopy (PHPM) where we combine pseudo ther-mal light source illumination and Hilbert spiral transform (HST) phase demodulation to achieve hybrid hardware -software-driven noise robustness and an increase in reso-lution of single-shot coherent QPM. Those advantageous features stem from physically altering the laser spatial coherence and numerically restoring spectrally overlapped object spatial frequencies. The capabilities of PHPM are demonstrated by analyzing calibrated phase targets and live HeLa cells in comparison with laser illumination and phase demodulation via temporal phase shifting (TPS) and Fourier transform (FT) techniques. The performed studies verified the unique ability of PHPM to combine single-shot imag-ing, noise minimization, and preservation of phase details.(c) 2022 Optica Publishing Group

关键词： Fourier transforms High numerical aperture optics image processing algorithms Phase retrieval Phase shift Spatial frequency

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HOUGH TRANSFORM USING CORDIC METHOD

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ELECTRONICS LETTERS 1989年第3期25卷 205-206页

作者： TIMMERMANN, D HAHN, H HOSTICKA, BJ FRAUNHOFER INST MICROELECTR CIRCUITS & SYST D-4100 DUISBURG 1FED REP GER

The purpose of the letter is to demonstrate the usefulness of the Cordic algorithm for implementation of image processing algorithms in dedicated hardware to achieve near real-time processing speed. The Cordic algorithm will be discussed, and also its application for line and circle detection as well as for arbitrary shapes using Hough transforms.

关键词： Cordic algorithm Cordic method Hough transforms arbitrary shapes circle detection computerised pattern recognition computerised picture processing dedicated hardware image processing algorithms line detection near real-time processing speed

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How good is your metalens? Experimental verification of metalens performance criterion

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OPTICS LETTERS 2020年第14期45卷 3869-3872页

作者： Engelberg, Jacob Wildes, Talia Zhou, Chen Mazurski, Noa Bar-David, Jonathan Kristensen, Anders Levy, Uriel Hebrew Univ Jerusalem Ctr Nanosci & Nanotechnol Dept Appl Phys IL-91904 Jerusalem Israel Tech Univ Denmark Dept Hlth Technol DK-2800 Lyngby Denmark

A metric for evaluation of overall metalens performance is presented. It is applied to determination of optimal operating spectral range of a metalens, both theoretically and experimentally. This metric is quite general and can be applied to the design and evaluation of future metalenses, particularly achromatic metalenses. (C) 2020 Optical Society of America

关键词： Diffractive lenses image processing algorithms image quality Low light levels Optical design software Optical systems

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End-to-end aperture layout optimization and image restoration for optical sparse aperture systems

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OPTICS LETTERS 2023年第10期48卷 2504-2507页

作者： Zhao, Wenxiu Zhang, Xiaofang Beijing Inst Technol Sch Opt & Photon Beijing 100081 Peoples R China

The optical sparse aperture (OSA) imaging technique is capable of improving the spatial resolution of a telescope while maintaining lower size, weight, and cost. The major-ity of OSA system researches separately focus on the design optimization of aperture layout and the method for image restoration, which have great design redundancy. In this Letter, an end-to-end design framework that simultaneously optimizes the aperture layout parameters of the OSA sys-tem and neural network parameters of image restoration is proposed, which achieves excellent imaging quality. The results show that adequate image mid-frequency informa-tion captured by the OSA system benefits network processing more than incomplete high-frequency information in a few directions. Based on this framework, we design a simplified OSA system on geostationary orbit. The simulation results show that our simplified OSA system with six sub-apertures measuring 1.2m each has a comparable imaging perfor-mance to a single-aperture system measuring 12 m. (c) 2023 Optica Publishing Group

关键词： Fast Fourier transforms image processing image processing algorithms image quality image restoration Spatial resolution

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400 m rolling-shutter-based optical camera communications link

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OPTICS LETTERS 2020年第5期45卷 1059-1062页

作者： Eso, Elizabeth Teli, Shivani Hassan, Navid Bani Vitek, Stanislav Ghassemlooy, Zabih Zvanovec, Stanislav Northumbria Univ Newcastle Opt Commun Res Grp Newcastle Upon Tyne Tyne & Wear England Czech Tech Univ Fac Elect Engn Prague Czech Republic Univ Strathclyde Dept Phys Glasgow Lanark Scotland Chinese Acad Sci QIEM HI Quanzhou Peoples R China

In this Letter, we develop a novel technique, to the best of our knowledge, to increase the link span (L-s) of a rolling shutter (RS)-based optical camera communications (OCC) system by reducing the spatial bandwidth of the camera in the out-of-focus regions. We demonstrate a 400 m line-of-sight RS-based OCC link, which is to date the longest L-s reported in these systems, and develop a detection method to extract the information out of the video frames, successfully. The proposed system relaxes the condition of a large surface area for the transmitter light source. Consequently, we show that at 400 m L-s and exposure times of 100-80 mu s, a data rate of 450 bps is achieved successfully. (C) 2020 Optical Society of America

关键词： CMOS cameras Diode lasers image processing algorithms image quality Light sources Liquid crystal displays

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Structural-descriptive method for the contour processing of optical images

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JOURNAL OF OPTICAL TECHNOLOGY 2000年第7期67卷 630-633页

作者： Zinov'lev, VG AF Mozhaiskii Mil Space Engn Univ St Petersburg Russia

A structural-descriptive method is proposed for the real-time recognition of optical images of observed objects by their contours. The contours of images of objects: are described on a rectangular "raster" in the form of strings of symbols of arbitrary length in Freeman chain code. A structure metric (the Levenshtein distance) is introduced to estimate the similarity of strings. The distance between strings is determined by discrete dynamic programming. A corresponding algorithm for the processing of optical images is discussed. (C) 2000 The Optical Society of America. [S1070-9762(00)00707-7].

关键词： algorithms Distortion image processing image processing algorithms Vision

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Microelectromechanical-systems-driven two-layer rotary-blade-based adjustable iris diaphragm

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OPTICS LETTERS 2012年第10期37卷 1745-1747页

作者： Zhou, Guangya Yu, Hongbin Du, Yu Chau, Fook Siong Natl Univ Singapore Dept Mech Engn Singapore 117576 Singapore

We report a miniature adjustable multi-blade iris diaphragm driven by microelectromechanical-systems-based electrostatic rotary microactuators. A proof-of-concept device is designed and fabricated using a silicon-on-insulator micromachining process. The diameter of the developed iris diaphragm aperture is experimentally demonstrated to be able to adjust from 0.45 to 1.56 mm. When used in a miniature camera lens system, the current prototype device is capable of providing an adjustment range of more than three full f/stops. (C) 2012 Optical Society of America

关键词： Apertures image processing algorithms Iris Laser beams Microactuators Optical microscopy

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Parallel Fabry-Perot interferometers fabricated on multicore-fiber for temperature and strain discriminative sensing

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OPTICS EXPRESS 2020年第3期28卷 3190-3199页

作者： Zhang, Cong Fu, Songnian Tang, Ming Liu, Deming Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan 430074 Peoples R China

We experimentally demonstrate parallel Fabry-Perot interferometers (FP's) fabrication in multicore-fiber with individually variable cavity length, for the purpose of discriminative sensing of temperature and strain. First, we theoretically find that, in order to obtain a small condition number of sensitivity matrix, it is necessary to fabricate parallel FPIs with large cavity difference in single multicore fiber. Then, parallel FPIs are inscribed by femtosecond laser selective micro-holes drilling on the seven-core fiber facet, together with fiber fusion splicing process. By the use of image processing algorithm, individual core position is precisely locked, and then parallel FPIs can be obtained on arbitrary two cores of seven-core fiber. With the location of parallel micro-holes and duration time of fiber fusion splicing adjusted, parallel FPIs with different cavity length of 26 mu m and 61 mu m can be simultaneously obtained at the central core and surrounding core, respectively. Consequently, each FPI possesses different sensitivity towards environmental temperature and strain. Finally, a proof-of-concept experiment verifies that relative measurement errors of both temperature and strain discriminative sensing are less than 0.5% and 2.5%, respectively. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Femtosecond fiber lasers Hollow core fibers image processing algorithms Multicore fibers Photonic crystal fibers Single mode fibers

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Detection approach for GEO space objects with a wide-field optical telescope array

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OPTICS EXPRESS 2023年第12期31卷 18717-18733页

作者： Yang, Wenbo Li, Zhenwei Liu, Ming Liu, Delong Sun, Jiannan Kang, Zhe Yu, Huanhuan Natl Astron Observ CAS Changchun Observ Changchun 130117 Peoples R China Chinese Acad Sci PMO Key Lab Space Object & Debris Observat Nanjing 210008 Peoples R China Natl Astron Observ CAS Beijing 100101 Peoples R China

In 2020, Changchun Observatory developed a 280 mm wide-field optical telescope array to improve surveillance of space debris in the geosynchronous belt. There are many advantages including a wide field of view, the ability to observe a large area of sky and high reliability. However, the wide field of view causes a significant number of background stars to appear in the image when photographing space objects, making it difficult to detect them. This research focuses on the precise detection of GEO space objects from images taken by this telescope array in order to position them in large quantities. Our work further investigates the motion feature of an object, namely that the object can be seen as being in a uniform linear motion for a brief length of time. Based on this feature, the belt can be divided into a number of smaller areas and the telescope array scans each smaller area one at a time from east to west. To detect objects in the subarea, a combination of image differencing with trajectory association is used. The image differencing algorithm is used to remove most stars and screen out suspected objects in the image. Next, the trajectory association algorithm is employed to further filter out the real objects among the suspected ones, and the trajectories attributed to the same object are linked. The feasibility and accuracy of the approach were verified by the experiment results. The accuracy rate of trajectory association exceeds 90% and on average, more than 580 space objects can be detected per observation night. Since the J2000.0 equatorial system can accurately describe the apparent position of an object, the object can be detected by using this coordinate system as opposed to the pixel coordinate system.

关键词： image deconvolution image processing image processing algorithms Imaging telescopes Optical flow Optical telescopes

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High-speed collagen fiber modeling and orientation quantification for optical coherence tomography imaging

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OPTICS EXPRESS 2019年第10期27卷 14457-14471页

作者： McLean, James P. Gan, Yu Lye, Theresa H. Qu, Dovina Lu, Helen H. Hendon, Christine P. Columbia Univ Fu Fdn Sch Engn & Appl Sci Elect Engn 1300 West 120th St New York NY 10025 USA Columbia Univ Fu Fdn Sch Engn & Appl Sci Biomed Engn 1300 West 120th St New York NY 10025 USA

Quantifying collagen fiber architecture has clinical and scientific relevance across a variety of tissue types and adds functionality to otherwise largely qualitative imaging modalities. Optical coherence tomography (OCT) is uniquely suited for this task due to its ability to capture the collagen microstructure over larger fields of view than traditional microscopy. Existing image processing techniques for quantifying fiber architecture, while accurate and effective, are very slow for processing large datasets and tend to lack structural specificity. We describe here a computationally efficient method for quantifying and visualizing collagen fiber organization. The algorithm is demonstrated on swine atria, bovine anterior cruciate ligament, and human cervical tissue samples. Additionally, we show an improved performance for images with crimped fiber textures and low signal to noise when compared to similar methods. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing image processing algorithms In vivo imaging Magnetic resonance imaging Nonlinear spatial filtering Speckle noise

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