2021
2021
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Record 241 of
Title:Multi-brightness layers with a genetic optimization algorithm for stereo matching under dramatic illumination changes
Author(s):Yang, Tao(1,2); Yang, Rui(3); Qiu, Yuehong(1)Source: Applied Optics Volume: 60 Issue: 24 DOI: 10.1364/AO.432015 Published: August 20, 2021Abstract:Stereo matching under dramatic illumination changes is a big challenge in imbalanced binocular vision, selfdriving cars, and the remote sensing image field. A novel, to the best of our knowledge, multi-brightness layer mechanism with a genetic optimization algorithm is proposed in this paper. The mechanism of multi-brightness layers transforms the two images with dramatic illumination changes into a series of matched pairs with similar brightness by the stretching function and histogram matching principle. Therefore, the large illumination variations are reduced greatly. Moreover, the initial disparities as first generation of genetic optimization approach are generated from matched pairs using fast segmentation local stereo matching to increase the efficiency and accuracy. For further improving the accuracy of disparity, an enhanced genetic optimization algorithm for stereo matching is designed to have more inliers and continuity. The experimental results comparing with state-of-theart stereo matching methods demonstrate that the proposed method has better performance in accuracy and stability. ? 2021 Optical Society of America.Accession Number: 20213410804893 -
Record 242 of
Title:Adaptive multiscale feature for object detection
Author(s):Yu, Xiaoyong(1,2); Wu, Siyuan(1); Lu, Xiaoqiang(1); Gao, Guilong(3)Source: Neurocomputing Volume: 449 Issue: DOI: 10.1016/j.neucom.2021.04.002 Published: August 18, 2021Abstract:In object detection, multiscale features are necessary to deal with objects with different size. Using Feature Pyramid Network (FPN) as the backbone network is a very popular paradigm in existing object detectors, we call this paradigm FPN+. However, feature fusion of FPN is insufficient to express object of similar size but different appearance due to the unidirectional feature fusion. We motivate and present Adaptive Multiscale Feature (AMF), a new multiscale feature fusion method with bidirectional feature fusion, using to solve the one-direction fusion of FPN. AMF module fuses multiscale features from two aspects: (1) shattering features by the way of CLSM; (2) fusing features by the way of channel-wise attention. The proposed AMF improves the expression ability of multiscale features of the backbone network, and effectively improves the performance of the object detector. The proposed feature fusion method can be added to all object detector, such as the one-stage detector, the two-stage detector, anchor-based detector and anchor-free based detector. Experimental results on the COCO 2014 dataset show that the proposed AMF module performs the popular FPN based detector. Whether anchored-free based detectors or anchored based detectors, performance of detector can be improved through AMF. And the resulting best model can achieve a very competitive mAP on COCO 2014 dataset. ? 2021 Elsevier B.V.Accession Number: 20211710256596 -
Record 243 of
Title:Precise on-Fiber Plasmonic Spectroscopy Using a Gradient-Index Microlens
Author(s):Jia, Peipei(1,5); Kong, Depeng(2); Li, Jiawen(3); Schartner, Erik(4); Ebendorff-Heidepriem, Heike(4)Source: Journal of Lightwave Technology Volume: 39 Issue: 1 DOI: 10.1109/JLT.2020.3026365 Published: January 1, 2021Abstract:Plasmonic spectroscopy has emerged as a powerful technique for interrogation of light in the subwavelength regime. Realization of active plasmonic elements on optical fibers can simplify the optical design, allow for performing remote tasks and thus extend the scope of plasmonic utilization. However, the optimization of fiber optics for improving the plasmonic excitation condition has been overlooked. Here we present a plasmonic spectroscopy platform that combines a gradient-index microlens and a single-mode optical fiber. This design ensures large-area and uniform illumination in normal incidence for the excitation of surface plasmon resonance. We demonstrate precise plasmonic spectroscopy with a fiber-optic platform by patterning a nanohole array onto the facet of a gradient-index microlens with our template transfer technique. The experimental spectra are almost identical to the simulated results under ideal conditions, with accurate resonance wavelength ( ? 1983-2012 IEEE.Accession Number: 20205209674760 -
Record 244 of
Title:Generation of densely-spaced time-bin entangled qubits on a chip
Author(s):Chemnitz, Mario(1); Sciara, Stefania(1); Fischer, Bennet(1); Crockett, Benjamin(1); Roztocki, Piotr(1); Yu, Hao(2); Wang, Zhiming(2); Morandotti, Roberto(3); Little, Brent E.(3); Chu, Sai T.(4); Moss, David J.(5)Source: 2021 Photonics North, PN 2021 Volume: Issue: DOI: 10.1109/PN52152.2021.9598004 Published: 2021Abstract:We present a compact scheme for the integrated generation of densely-spaced time-bin entangled two-photon qubits using an on-chip unbalanced interferometer and a spiral waveguide. We show quantum interference with visibilities as high as 99%. ? 2021 IEEE.Accession Number: 20220411518346 -
Record 245 of
Title:Algorithm of Pulmonary Vascular Segment and Centerline Extraction
Author(s):Qiu, Shi(1); Lian, Jie(2); Ding, Yan(3); Zhou, Tao(4); Liang, Ting(5,6)Source: Computational and Mathematical Methods in Medicine Volume: 2021 Issue: DOI: 10.1155/2021/3859386 Published: 2021Abstract:Because pulmonary vascular lesions are harmful to the human body and difficult to detect, computer-assisted diagnosis of pulmonary blood vessels has become the focus and difficulty of the current research. An algorithm of pulmonary vascular segment and centerline extraction which is consistent with the physician's diagnosis process is proposed for the first time. We construct the projection of maximum density, restore the vascular space information, and correct random walk algorithm to satisfy automatic and accurate segmentation of blood vessels. Construct a local 3D model to restrain Hessian matrix when extracting centerline. In order to assist the physician to make a correct diagnosis and verify the effectiveness of the algorithm, we proposed a visual expansion model. According to the 420 high-resolution CT data of lung blood vessels labeled by physicians, the accuracy of segmentation algorithm AOM reached 93%, and the processing speed was 0.05 s/frame, which achieved the clinical application standards. ? 2021 Shi Qiu et al.Accession Number: 20214511125455 -
Record 246 of
Title:A MOSFET-based high voltage nanosecond pulse module for the gating of proximity-focused microchannel plate image-intensifier
Author(s):Fang, Yuman(1,2); Gou, Yongsheng(1); Zhang, Minrui(1); Wang, Junfeng(1); Tian, Jinshou(1,3)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 987 Issue: DOI: 10.1016/j.nima.2020.164799 Published: January 21, 2021Abstract:Gate modules based on avalanche technology for photocathode gating to proximity-focused microchannel-plate image intensifier (MCPII) are often limited to short gate exposures. A nanosecond pulse module based on MOSFET devices has been demonstrated at our lab, which is capable of generating pulses of adjustable full width at half maximum (FWHM) from 3 ns to D.C. operation with 1 ns switching time and a burst repetition rate up to 4 MHz. A method of supplying gate-current pulses to the MOSFET device is adopted to increase the switching speed based on the totem pole driver. Nanosecond optical gating time of an 18-mm proximity-focused MCPII with a metallic underlay photocathode was obtained. A MCPII with standard multi-alkali photocathode was analyzed for comparison. Moreover, a photocathode-MCP model based on the Finite Integral Technique (FIT) is developed to investigate the dependence of the gating time on the sheet resistance of the photocathode. ? 2020 Elsevier B.V.Accession Number: 20204809550114 -
Record 247 of
Title:Optical design and simulation of Einstein Probe satellite follow-up X-ray telescope
Author(s):Zhu, Yuxuan(1); Lu, Jingbin(1); Yang, Yangji(2); Cong, Min(2); Sheng, Lizhi(3); Qiang, Pengfei(3); Cui, Weiwei(2); Zhang, Ziliang(2); Wang, Yusa(2); Han, Dawei(2); Li, Wei(2); Wang, Juan(2); Huo, Jia(2); Li, Maoshun(2); Zhao, Xiaofan(2); Yu, Nian(2); Song, Zeyu(2); Ma, Jia(2); Lv, Zhonghua(2); Zhao, Zijian(2); Wang, Hao(2); Hou, Dongjie(2); Chen, Can(2); Chen, Tianxiang(2); Yang, Xiongtao(2); Luo, Laidan(2); Lu, Bing(2); Xu, Jingjing(2); Chen, Yehai(4); Chen, Yong(2)Source: Optical Engineering Volume: 60 Issue: 2 DOI: 10.1117/1.OE.60.2.025102 Published: February 1, 2021Abstract:The Follow-up X-ray Telescope (FXT), a key payload onboard the Einstein Probe sallite (EP), is equipped with a Wolter-I X-ray focusing mirror system. We introduce the principle of such a mirror system and analyze the influence of the mirror gap in the multishell nested mirror of the FXT on the effective area, stray-light ratio, and vignetting. To ensure that no occlusion occurs within adjacent shells and minimize stray-light ratio, the size of the gap is set to a optimized value for corresponding shell. We finished a design of a 54-shell mirror system according to these results. The optical performance of the design was then simulated using a Monte Carlo algorithm and the ray-tracing principle. The simulation shows that the effective area is 414.5 ± 0.2 cm2 at 1.25 keV (considering the spider), and the field of view is 64 arcmin in diameter. These parameters meet the optical requirements of the FXT. ? 2021 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20211010034322 -
Record 248 of
Title:A driver-assistance algorithm based on multi-feature fusion
Author(s):Zhou, Dongmei(1); Qiu, Shi(2); Song, Yang(3)Source: Infrared Physics and Technology Volume: 116 Issue: DOI: 10.1016/j.infrared.2021.103747 Published: August 2021Abstract:The lane line is difficult to be distinguished in visible light for driver assistance, so a multi-feature fusion model is built from the perspective of infrared images to realize assistant driving. Firstly, the features of infrared imaging are analyzed, and the Enet network is improved to focus on the area of the lane line and locate the passable area. Then, the previous vehicle is located to guide the current vehicle based on the fuzzy set theory. Finally, a spatiotemporal association model is constructed. By constructing the relationship between the guiding vehicle and spatiotemporal traffic, the relationship between human-computer interaction is indirectly established to guide vehicle assisted driving. Our experimental results show that the proposed algorithm is in line with the manual driving process, and good results can be achieved under complex road conditions. ? 2021Accession Number: 20211910345766 -
Record 249 of
Title:Design and Realization of Visible/LWIR Dual-color Common Aperture Optical System
Author(s):Ma, Zhanpeng(1,2); Xue, Yaoke(1,4,5); Shen, Yang(1); Zhao, Chunhui(3); Zhou, Canglong(1,2); Lin, Shangmin(1,2); Wang, Hu(1,2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 50 Issue: 5 DOI: 10.3788/gzxb20215005.0511002 Published: May 25, 2021Abstract:In order to solve the problems of poor imaging quality, complex structure and large volume of existing dual-band common aperture cameras, a visible/long-wave infrared dual-color optical system was proposed. Simultaneous imaging is achieved by sharing the front-end reflection structure in the two bands and adding a dichroic beam splitter on the back of the main mirror, thereby ensuring the compactness of the system structure. The influence of the dichroic beam splitter on the infrared band imaging was analyzed in detail, as well as the influence of different angles of the dichroic beam splitter from vertical direction. The correct system of long wave infrared band and the image plane were eccentrically processed by -2.39 mm, so the image quality of the infrared band was greatly improved. The validity of the analysis conclusion was verified by the field test imaging. The results show that the system has loose tolerances, simple structure, and a few optical components. This system has the advantages of easy processing, installation, and strong engineering feasibility, which can effectively improve the target detection and recognition capabilities of the camera. ? 2021, Science Press. All right reserved.Accession Number: 20212510544783 -
Record 250 of
Title:Development of low-loss lead-germanate glass for mid-infrared fiber optics: I. glass preparation optimization
Author(s):Wang, Pengfei(1,2,3); Bei, Jiafang(1); Ahmed, Naveed(1); Ng, Alson Kwun Leung(1); Ebendorff-Heidepriem, Heike(1)Source: Journal of the American Ceramic Society Volume: 104 Issue: 2 DOI: 10.1111/jace.17503 Published: February 2021Abstract:Reducing the mid-infrared attenuation loss due to absorption of hydroxyl (OH) groups and scattering of metallic Pb species for lead-germanate glass is essential to pave the way for their applications as low-loss mid-infrared fiber optics. In the first part of this study, we report the understanding of the factors that determine dehydration efficiency and metallic Pb formation during the lead-germanate glassmelting process. Combining a dry O2-rich atmosphere containing ultra-dry N2 together with the use of chloride dehydration agent and nitrate oxidation agent compound was found to enable efficient dehydration effect and absence of metallic Pb scattering sources in the dehydrated glasses. This glassmelting procedure overcomes previous limitations on the preparation of similar kinds of heavy-metal oxide glasses, where only pure O2 atmosphere was used and/or use of fluoride dehydration agent deteriorated the glass thermal stability. This work provides guidance for developing other low-loss mid-infrared glasses/fibers containing multivalent heavy-metal ions such as Pb, Bi, Te, Sb, etc. ? 2020 American Ceramic Society (ACERS)Accession Number: 20204209343663 -
Record 251 of
Title:Mechanism of All-Optical Spatial Light Modulation in Graphene Dispersion
Author(s):Liu, Shan(1,2); Han, Jing(1); Cheng, Xuemei(1,2); Wang, Xing(2); Zhang, Qian(3); He, Bo(1); Jiao, Tengfei(1); Ren, Zhaoyu(1)Source: Journal of Physical Chemistry C Volume: 125 Issue: 30 DOI: 10.1021/acs.jpcc.1c04423 Published: August 5, 2021Abstract:Graphene is a superb material with significant potential in broadband all-optical modulation. However, the mechanism of the all-optical modulation in graphene dispersion is still under debate. Here, we report on a pump power-dependent spatial light modulation by using the 780 nm CW laser as the pump and signal beams via graphene dispersion. The results indicate that graphene is able to convert the Gaussian signal beam into a hollow beam with a ring pattern. Examining the temporal evolution of the ring pattern, we found that spatial cross-phase modulation (SXPM) plays the dominant role at low pump power, while nonlinear scattering (NLS) becomes dominant when the pump power is high. Furthermore, the dependence of the size and intensity of the signal ring pattern on the pump power is investigated. The results can be well explained by SXPM, NLS, and saturation absorption (SA) effects. Finally, an all-optical switch is developed based on the dependence of the signal intensity on the pump power. It is demonstrated that both in-phase and out-phase modulation can be realized in one system. This work not only provides useful information in understanding the mechanism of graphene in interacting with the light, but also suggests a new way to produce hollow beam with tunable size and achieve an all-optical switch with both in-phase and out-phase modulation. ? 2021 American Chemical Society.Accession Number: 20213310767949 -
Record 252 of
Title:Development of low-loss lead-germanate glass for mid-infrared fiber optics: II. preform extrusion and fiber fabrication
Author(s):Wang, Pengfei(1,2,3); Ng, Alson Kwun Leung(1); Dowler, Alastair(1); Ebendorff-Heidepriem, Heike(1)Source: Journal of the American Ceramic Society Volume: 104 Issue: 2 DOI: 10.1111/jace.17518 Published: February 2021Abstract:For lead-germanate glass fibers, reducing the content of hydroxyl (OH) groups and the formation of metallic Pb species is essential to pave the way for their applications as low-loss mid-IR fiber optics since OH and metallic Pb species cause intense absorption and scattering loss, respectively, in the mid-IR spectral range. The first part of this study reported the optimization of the glass melting procedure to obtain low amount of OH while preventing formation of metallic Pb species in lead-germanate glass. Here, the second part of this study reports the investigation of the process conditions to fabricate low-loss lead-germanate glass fiber through further understanding of the co-effects of glass melting and heat treatment atmospheres on the formation of nano- and micron-scale metallic Pb species in both the as-produced and heat treated lead-germanate glasses. Finally, using this advance in knowledge, we successfully fabricated low-loss lead-germanate glass fibers with no presence of reduced metallic Pb particles by optimizing dehydration agent, glass melting, preform extrusion and fiber drawing conditions. The optimized fabrication conditions reduced the unstructured fiber loss by almost one order to? ? 2020 American Ceramic Society (ACERS)Accession Number: 20204409443313