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Study of an image autofocus method based on power threshold function wavelet reconstruction and a quality evaluation algorithm

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APPLIED OPTICS 2018年第33期57卷 9714-9721页

作者： Yan, Zhidan Chen, Guo Xu, Wenyi Yang, Chunmei Lu, Yang China Univ Petr East China Coll Informat & Control Engn Changjiangxi Rd 66 Qingdao 266580 Shandong Peoples R China Tianjin Univ State Key Lab Precis Measuring Technol & Instrume Univ Weijin Rd 92 Tianjin 300072 Peoples R China

As a key component in optical microscopy imaging systems, autofocus technology has a significant effect on imaging quality. In this paper, an optical microscopy autofocus method that includes a wavelet denoising algorithm based on a power threshold function and a Brenner image quality evaluation algorithm is presented. Experimental results show that the power threshold function wavelet denoising algorithm, which can be adopted to obtain more realistic optical images, is superior to the traditional soft, hard, hyperbolic, and exponential threshold functions in terms of peak signal-to-noise ratio, signal-to-noise ratio, mean squared error, and histogram indicators;moreover, compared to the Roberts, sum modulus difference (SMD), and energy gradient functions, the Brenner image quality evaluation algorithm can be used to quickly and accurately lock onto the focal plane. By integrating and applying these two core algorithms in the autofocus image acquisition system of a microscope, the image sharpness and focusing quality are greatly improved, which benefits the further evaluation of images. (C) 2018 Optical Society of America

关键词： image processing image processing algorithms image quality image resolution Imaging systems Signal processing

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Quantitative multi-contrast in vivo mouse imaging with polarization diversity optical coherence tomography and angiography

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BIOMEDICAL OPTICS EXPRESS 2020年第12期11卷 6945-6961页

作者： Hsu, Destiny Kwon, Ji Hoon Ng, Ringo Makita, Shuichi Yasuno, Yoshiaki Sarunic, Marinko V. Ju, Myeong Jin Simon Fraser Univ Biomed Opt Res Grp Dept Engn Sci Burnaby BC Canada Univ Tsukuba Computat Opt Grp Inst Appl Phys Tsukuba Ibaraki Japan Univ British Columbia Dept Ophthalmol & Visual Sci Vancouver BC Canada Univ British Columbia Sch Biomed Engn Vancouver BC Canada

Retinal microvasculature and the retinal pigment epithelium (RPE) play vital roles in maintaining the health and metabolic activity of the eye. Visualization of these retina structures is essential for pre-clinical studies of vision-robbing diseases, such as age-related macular degeneration (AMD). We have developed a quantitative multi-contrast polarization diversity OCT and angiography (QMC-PD-OCTA) system for imaging and visualizing pigment in the RPE using degree of polarization uniformity (DOPU), along with flow in the retinal capillaries using OCT angiography (OCTA). An adaptive DOPU averaging kernel was developed to increase quantifiable values from visual data, and QMC en face images permit simultaneous visualization of vessel location, depth, melanin region thickness, and mean DOPU values, allowing rapid identification and differentiation of disease symptoms. The retina of five different mice strains were measured in vivo, with results demonstrating potential for pre-clinical studies of retinal disorders. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing image processing algorithms image quality In vivo imaging Retinal nerve fiber layer Small animal imaging

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Co-designed annular binary phase masks for depth-of-field extension in single-molecule localization microscopy

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OPTICS EXPRESS 2020年第22期28卷 32426-32446页

作者： Leveque, Olivier Kulcsar, Caroline Lee, Antony Sauer, Herve Aleksanyan, Artur Bon, Pierre Cognet, Laurent Goudail, Francois Univ Paris Saclay Inst Opt Lab Charles Fabry CNRSGrad Sch F-91127 Palaiseau France Univ Bordeaux Lab Photon Numer & Nanosci UMR 5298 F-33400 Talence France LP2N UMR 5298 Inst Opt F-33400 Talence France LP2N UMR 5298 CNRS F-33400 Talence France

Single-molecule localization microscopy has become a prominent approach to study structural and dynamic arrangements of nanometric objects well beyond the diffraction limit. To maximize localization precision, high numerical aperture objectives must be used;however, this inherently strongly limits the depth-of-field (DoF) of the microscope images. In this work, we present a framework inspired by "optical co-design" to optimize and benchmark phase masks, which, when placed in the exit pupil of the microscope objective, can extend the DoF in the realistic context of single fluorescent molecule detection. Using the Cramer-Rao bound (CRB) on localization accuracy as a criterion, we optimize annular binary phase masks for various DoF ranges, compare them to Incoherently Partitioned Pupil masks and show that they significantly extend the DoF of single-molecule localization microscopes. In particular we propose different designs including a simple and easy-to-realize two-ring binary mask to extend the DoF. Moreover, we demonstrate that a simple maximum likelihood-based localization algorithm can reach the localization accuracy predicted by the CRB. The framework developed in this paper is based on an explicit and general information theoretic criterion, and can thus be used as an engineering tool to optimize and compare any type of DoF-enhancing phase mask in high resolution microscopy on a quantitative basis. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Diffraction limit High numerical aperture optics image processing algorithms image quality Phase modulation Three dimensional imaging

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image analysis algorithms for cell contour recognition in budding yeast

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OPTICS EXPRESS 2008年第17期16卷 12943-12957页

作者： Kvarnstrom, Mats Logg, Katarina Diez, Alfredo Bodvard, Kristofer Kall, Mikael Fraunhofer Chalmers Res Ctr SE-41288 Gothenburg Sweden Chalmers Univ Technol Dept Appl Phys SE-41296 Gothenburg Sweden

Quantification of protein abundance and subcellular localization dynamics from fluorescence microscopy images is of high contemporary interest in cell and molecular biology. For large-scale studies of cell populations and for time-lapse studies, such quantitative analysis can not be performed effectively without some kind of automated image analysis tool. Here, we present fast algorithms for automatic cell contour recognition in bright field images, optimized to the model organism budding yeast (Saccharomyces cerevisiae). The cell contours can be used to effectively quantify cell morphology parameters as well as protein abundance and subcellular localization from overlaid fluorescence data. (C) 2008 Optical Society of America.

关键词： Fluorescence microscopy High throughput optics image analysis image processing image processing algorithms Molecular probes

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Simultaneous measurements of foveal and peripheral aberrations with accommodation in myopic and emmetropic eyes

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BIOMEDICAL OPTICS EXPRESS 2021年第12期12卷 7422-7433页

作者： Romashchenko, Dmitry Papadogiannis, Petros Unsbo, Peter Lundstrom, Linda Royal Inst Technol Dept Appl Phys S-11421 Stockholm Sweden Johnson & Johnson Vis R&D NL-9728 NX Groningen Netherlands

The difference in peripheral retinal image quality between myopic and emmetropic eyes plays a major role in the design of the optical myopia interventions. Knowing this difference under accommodation can help to understand the limitations of the currently available optical solutions for myopia control. A newly developed dual-angle open-field sensor was used to assess the simultaneous foveal and peripheral (20 degrees nasal visual field) wavefront aberrations for five target vergences from -0.31 D to -4.0 D in six myopic and five emmetropic participants. With accommodation, the myopic eyes showed myopic shifts, and the emmetropic eyes showed no change in RPR. Furthermore, RPR calculated from simultaneous measurements showed lower infra-subject variability compared to the RPR calculated from peripheral measurements and target vergence. Other aberrations, as well as modulation transfer functions for natural pupils, were similar between the groups and the accommodation levels, foveally and peripherally. Results from viewing the same nearby target with and without spectacles by myopic participants suggest that the accommodative response is not the leading factor controlling the amplitude of accommodation microfluctuations. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.

关键词： Contact lenses image processing algorithms image quality Refractive anomalies Visual accommodation Wavefront aberrations

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Negative optical radiation force and spin torques on subwavelength prolate and oblate spheroids in fractional Bessel-Gauss pincers light-sheets

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2017年第7期34卷 1246-1254页

作者： Mitri, F. G. Chevron Area Technol ETC 52 Santa Fe NM 87508 USA

Fractional Bessel-Gauss light-sheets [J. Opt. 19, 055602 ( 2017)], which correspond to finite optical "slices" in 2D and possess asymmetric slit openings and bending characteristics, are examined from the standpoint of optical radiation force and spin torque theories for a subwavelength spheroid with arbitrary orientation in space. The vector angular spectrum decomposition method in addition to the Lorenz gauge condition and Maxwell's equations are used to determine the Cartesian components of the incident radiated electric field of the Bessel-Gauss light-sheets. In the framework of the dipole approximation, the numerical results for the Cartesian components of the optical radiation force and spin torque vectors show that negative forces ( oriented in the opposite direction of wave motion) and spin torques arise depending on the beam parameters, the orientation of the subwavelength spheroid in 3D space, and its aspect ratio (i.e., prolate versus oblate). The spin torque sign reversal reveals that counter-clockwise or clockwise rotations around the center of mass of the spheroid can occur. The results find important applications in the application of auto-focusing light-sheets in particle manipulation, rotation, and optical sorting devices. (C) 2017 Optical Society of America

关键词： Electric fields image processing algorithms Magnetic fields Numerical simulation Optical force Wave propagation

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Bead-based multiplex detection of dengue biomarkers in a portable imaging device

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BIOMEDICAL OPTICS EXPRESS 2020年第11期11卷 6154-6167页

作者： Yuan, Xilong Garg, Srishti De Haan, Kevin Fellouse, Frederic A. Gopalsamy, Anupriya Tykvart, Jan Sidhu, Sachdev S. Varma, Manoj M. Pal, Parama Hillan, Edith M. Dou, James Jiahua Aitchison, J. Stewart Univ Toronto Dept Elect & Comp Engn Toronto ON Canada Univ Calif Los Angeles Dept Elect & Comp Engn Los Angeles CA 90095 USA Univ Toronto Donnelly Ctr Toronto ON Canada Univ Toronto Dept Med Genet Toronto ON Canada DIANA Biotechnol Sro Vestec 25250 Czech Republic Indian Inst Sci Ctr Nano Sci & Engn Bengaluru Karnataka India Tata Consultancy Serv TCS Res & Innovat Bengaluru Karnataka India Univ Toronto Lawrence S Bloomberg Fac Nursing Toronto ON Canada Thinkari Res Inc Mississauga ON Canada

Dengue is one of the most rapidly spreading mosquito-borne viral diseases in the world. Differential diagnosis is a crucial step for the management of the disease and its epidemiology. Point-of-care testing of blood-borne dengue biomarkers provides an advantageous approach in many health care settings, and the ability to follow more than one biomarker at once could significantly improve the management of the disease. Bead-based multiplex technologies (suspension array) can measure multiple biomarker targets simultaneously by using recognition molecules immobilized on microsphere beads. The overarching objective of our work is to develop a portable detection device for the simultaneous measurement of multiple biomarkers important in dengue diagnosis, monitoring and treatment. Here, we present a bead-based assay for the detection of one of the four serotypes of dengue virus non-structural protein (DENV-NS1) as well as its cognate human IgG. In this system, the fluorescent microspheres containing the classification fluorophore and detection fluorophore are imaged through a microfluidic chip using an infinity-corrected microscope system. Calibration curves were plotted for median fluorescence intensity against known concentrations of DENV-NS1 protein and anti-NS1 human IgG. The limit of quantitation was 7.8 ng/mL and 15.6 ng/mL, respectively. The results of this study demonstrate the feasibility of the multiplex detection of dengue biomarkers and present its analytical performance parameters. The proposed imaging device holds potential for point-of-care testing of biomarkers on a highly portable system, and it may facilitate the diagnosis and prevention of dengue as well as other infectious diseases. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Diode lasers Diode pumped lasers Forward scattering image processing algorithms Optical sensing Stray light

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Do EnChroma glasses improve color vision for colorblind subjects?

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OPTICS EXPRESS 2018年第22期26卷 28693-28703页

作者： Gomez-Robledo, L. Valero, E. M. Huertas, R. Martinez-Domingo, M. A. Hernandez-Andres, J. Univ Granada Dept Opt Granada Spain

The commercialization of EnChroma glasses has generated great expectations for people to be able to see new colors or even correct color vision deficiency (CVD). We evaluate the effectiveness of these glasses using two complementary strategies for the first time. The first consists of using the three classical types of tests - recognition, arrangement and discrimination - with and without glasses, with a high number of individuals. In the second, we use the spectral transmittance of the glasses to simulate the appearance of stimuli in a set of scenes for normal observers and observers with CVD. The results show that the glasses introduce a variation of the perceived color, but neither improve results in the diagnosis tests nor allow the observers with CVD to have a more normal color vision. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Color blindness Color spaces Color vision image processing algorithms Standard observers Visible light

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Simple and sensitive technique for alignment of the pinhole of a spatial filter of a high-energy, high-power laser system

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APPLIED OPTICS 2013年第12期52卷 2546-2554页

作者： Sharma, Avnish Kumar Patidar, Rajesh Kumar Daiya, Deepak Joshi, Anandverdhan Naik, Prasad Anant Gupta, Parshotam Dass Raja Ramanna Ctr Adv Technol Laser Plasma Div Indore 452013 Madhya Pradesh India

In this paper, a new method for alignment of the pinhole of a spatial filter (SF) has been proposed and demonstrated experimentally. The effect of the misalignment of the pinhole on the laser beam profiles has been calculated for circular and elliptical Gaussian laser beams. Theoretical computation has been carried out to illustrate the effect of an intensity mask, placed before the focusing lens of the SF, on the spatial beam profile after the pinhole of the SF. It is shown, both theoretically and experimentally, that a simple intensity mask, consisting of a black dot, can be used to visually align the pinhole with a high accuracy of 5% of the pinhole diameter. The accuracy may be further improved using a computer-based image processing algorithm. Finally, the proposed technique has been demonstrated to align a vacuum SF of a compact 40 J Nd:phosphate glass laser system. (C) 2013 Optical Society of America

关键词： image processing algorithms Laser beams Laser systems Optical amplifiers Optical parametric chirped pulse amplification Solid state lasers

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Rapid assembly of gold nanoparticle-based microstructures using optically-induced electrokinetics

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OPTICAL MATERIALS EXPRESS 2014年第11期4卷 2368-2380页

作者： Liang, Wenfeng Liu, Lianqing Lai, Sam Hok-Sum Wang, Yuechao Lee, Gwo-Bin Li, Wen Jung Chinese Acad Sci Shenyang Inst Automat State Key Lab Robot Shenyang 110016 Peoples R China Shenyang Jianzhu Univ Sch Transportat & Mech Engn Shenyang 110168 Peoples R China City Univ Hong Kong Dept Mech & Biomed Engn Hong Kong Hong Kong Peoples R China Natl Tsing Hua Univ Dept Power Mech Engn Hsinchu Taiwan

This paper presents a rapid approach for assembling gold nanoparticles (AuNPs)-based microstructures using optically-induced electrokinetics. Results showed that number of AuNPs in the assembled microstructures could be controlled by adjusting the input optically-induced electrokinetics parameters. The formation conditions were experimentally investigated by varying several key electrokinetics parameters, and the results were compared to a numerical simulation of the electrokinetic forces. The experimental results were also analyzed by counting the number of deposited AuNPs in a microstructure using an image processing algorithm. We will show that the optimal parameters for this optoelectronic AuNPs assembly method are electric field frequency range from 9 to 11 kHz with a voltage range of 18-20 V-pp, and an optical exposure time of similar to 120 s. (C) 2014 Optical Society of America

关键词： High numerical aperture optics image processing algorithms Nanopositioning equipment Numerical simulation Solar cell efficiency Thin films

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