2015
2015
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Record 337 of
Title:Adaptive nonuniformity correction algorithm based on multiscale temporal moment matching
Author(s):Leng, Han-Bing(1); Hu, Bing-Liang(1); Zhou, Zuo-Feng(1); Tang, Li-Nao(1); Zhang, Jian(1); Yan, A-Qi(1)Source: Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves Volume: 34 Issue: 4 DOI: 10.11972/j.issn.1001-9014.2015.04.004 Published: August 1, 2015Abstract:The fixed pattern noise of uncooled infrared focal plane arrays has the similar characteristics with the stripe noise. By researching the moment matching and temporal high-pass filter, a novel multiscale temporal moment matching nonuniformity correction algorithm was proposed. In the proposed algorithm, global motion was first identified by the Gaussian pyramid of the adjacent uncorrected images. Then the temporal moment matching was performed in all levels of Gaussian pyramids and Laplacian pyramids. The experimental results with the real infrared video sequences have shown that the proposed algorithm can significantly increase the convergence speed and reduce the ghosting artifacts. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20154501513537 -
Record 338 of
Title:Performance analysis of laser transmitting system for fourier telescope
Author(s):Luo, Xiujuan(1); Zhang, Yu(1); Gao, Cunxiao(1); Ren, Juan(1); Cao, Bei(1); Liu, Hui(1); Chen, Minglai(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 3 DOI: 10.3788/AOS201535.0314001 Published: March 10, 2015Abstract:The performance of Fourier telescope transmitting system directly affects the image resolution and quality. The parameters and performance requirements of laser are analyzed. The design outline of fiber laser is presented. Meanwhile, the point is put forward that the laser coherence length need to be at least 1.6 times of the residual optical path. The stability of laser power and frequency is simulated. To ensure the stability of the laser, some methods are put forward from the points of design, algorithm and practice. Furthermore, combined with the results of simulation and experiment, the influences of the transmitter performance on image quality is analyzed, from the aspects of transmitting aperture layout, aperture amount, position precision and the beam pointing error. And point out that baseline redundancy, image resolution, target spectrum and image quality are the factors should be synthetically considered when arranging transmitter array. The formula for calculating the number of transmitting apertures is obtained based on the two-dimensional sampling theorem and the statistical analysis results. The transmitting aperture number is calculated for the Fourier telescope whose resolution would be 5 cm for objects in 1000 km low earth orbit. In addition, it is concluded that the transmitting aperture position error should be less than 5% of the minimum aperture spacing. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20151400716497 -
Record 339 of
Title:Adaptive nonuniformity correction for infrared images based on temporal moment matching
Author(s):Leng, Hanbing(1); Yi, Bo(1); Xie, Qingsheng(1); Tang, Li'nao(1); Gong, Zhendong(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 4 DOI: 10.3788/AOS201535.0410003 Published: April 10, 2015Abstract:The response nonuniformity of uncooled infrared focal plane arrays is very similar to the stripe noise. Scene-based nonuniformity correction algorithm is an effective way to enhance the image quality and compensate the response drift. Based on the study of moment matching theory, a novel temporal moment matching nonuniformity correction algorithm is proposed. In the proposed algorithm, changing column is identified by the adjacent frames after moment matching, the correction coefficients are updated adaptively in temporal domain. The experimental results with the real infrared video sequences have shown that the proposed algorithm can significantly increase the convergence speed and reduce the ghosting artifacts. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152300916613 -
Record 340 of
Title:Learning a tracking and estimation integrated graphical model for human pose tracking
Author(s):Zhao, Lin(1); Gao, Xinbo(1); Tao, Dacheng(2); Li, Xuelong(3)Source: IEEE Transactions on Neural Networks and Learning Systems Volume: 26 Issue: 12 DOI: 10.1109/TNNLS.2015.2411287 Published: December 1, 2015Abstract:We investigate the tracking of 2-D human poses in a video stream to determine the spatial configuration of body parts in each frame, but this is not a trivial task because people may wear different kinds of clothing and may move very quickly and unpredictably. The technology of pose estimation is typically applied, but it ignores the temporal context and cannot provide smooth, reliable tracking results. Therefore, we develop a tracking and estimation integrated model (TEIM) to fully exploit temporal information by integrating pose estimation with visual tracking. However, joint parsing of multiple articulated parts over time is difficult, because a full model with edges capturing all pairwise relationships within and between frames is loopy and intractable. In previous models, approximate inference was usually resorted to, but it cannot promise good results and the computational cost is large. We overcome these problems by exploring the idea of divide and conquer, which decomposes the full model into two much simpler tractable submodels. In addition, a novel two-step iteration strategy is proposed to efficiently conquer the joint parsing problem. Algorithmically, we design TEIM very carefully so that: 1) it enables pose estimation and visual tracking to compensate for each other to achieve desirable tracking results; 2) it is able to deal with the problem of tracking loss; and 3) it only needs past information and is capable of tracking online. Experiments are conducted on two public data sets in the wild with ground truth layout annotations, and the experimental results indicate the effectiveness of the proposed TEIM framework. ? 2015 IEEE.Accession Number: 20151400711780 -
Record 341 of
Title:Design of the relay lens for infrared system coupled with imaging fiber bundle
Author(s):Yan, Xingtao(1); Li, Fu(1); Yang, Jianfeng(1); Xue, Bin(1); Ma, Xiaolong(1); Lv, Juan(1); He, Yinghong(1); Zhao, Yiyi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9676 Issue: DOI: 10.1117/12.2197992 Published: 2015Abstract:Relay lens is an important element for infrared system coupled with imaging fiber bundle. According to the basic composition and structural characteristics of infrared system coupled with imaging fiber bundle, this paper put forward the general principle and method of its relay lens design, then a material relay lens has been designed by ZEMAX with definite performance index. It has a working spectral coverage from 3.7μm to 4.8μm, focal length of 33.5mm, magnification of-0.6, linear field of view of 12mm, objective numerical aperture of 0.15. It is objective telecentric and is adapted to the relay of infrared detector and imaging fiber bundle. The total lens has two aspheric surfaces and only four pieces of singlet. Its MTF value is 0.7@17 lp/mm, and distortion is-0.19%. After necessary tolerance analysis and structural design, this relay lens has been fabricated. The optical performances fulfill the design requirements and clear images have been got by this lens. These prove the validity and rationality of the design method. It gives a foundational guidance for such relay lens design. ? 2015 SPIE.Accession Number: 20155201717464 -
Record 342 of
Title:A photonic saturable absorber in chalcogenide glass
Author(s):Minardi, S.(1); Cheng, G.(2,3); D'Amico, C.(2); Stoian, R.(2)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: Published: July 21, 2014Abstract:nullAccession Number: 20171503550351 -
Record 343 of
Title:Laser scanning stereomicroscopy for fast volumetric imaging with two-photon excitation and scanned Bessel beams
Author(s):Yang, Yanlong(1,2); Zhou, Xing(1); Li, Runze(1); Van Horn, Mark(3); Peng, Tong(1); Lei, Ming(1); Wu, Di(1); Chen, Xun(2); Yao, Baoli(1); Ye, Tong(2)Source: Progress in Biomedical Optics and Imaging - Proceedings of SPIE Volume: 9329 Issue: DOI: 10.1117/12.2079646 Published: 2015Abstract:Bessel beams have been used in many applications due to their unique optical properties of maintaining their intensity profiles unchanged during propagation. In imaging applications, Bessel beams have been successfully used to provide extended focuses for volumetric imaging and uniformed illumination plane in light-sheet microscopy. Coupled with two-photon excitation, Bessel beams have been successfully used in realizing fluorescence projected volumetric imaging. We demonstrated previously a stereoscopic solution-two-photon fluorescence stereomicroscopy (TPFSM)-for recovering the depth information in volumetric imaging with Bessel beams. In TPFSM, tilted Bessel beams were used to generate stereoscopic images on a laser scanning two-photon fluorescence microscope; upon post image processing we could successfully provide 3D perception of acquired volume images by wearing anaglyph 3D glasses. However, tilted Bessel beams were generated by shifting either an axicon or an objective laterally; the slow imaging speed and severe aberrations made it hard to use in real-time volume imaging. In this article, we report recent improvements of TPFSM with newly designed scanner and imaging software, which allows 3D stereoscopic imaging without moving any of the optical components on the setup. This improvement has dramatically improved focusing qualities and imaging speed so that the TPFSM can be performed potentially in real-time to provide 3D visualization in scattering media without post image processing. ? 2015 SPIE.Accession Number: 20152600973986 -
Record 344 of
Title:Digital holographic shape measurement using Fizeau microscopy
Author(s):Abdelsalam, D.G.(1,2); Min, Junwei(1); Kim, Daesuk(3); Yao, Baoli(1)Source: Chinese Optics Letters Volume: 13 Issue: 10 DOI: 10.3788/COL201513.100701 Published: October 10, 2015Abstract:We present a Fizeau interferometer using a microscopic objective as a tool for surface contouring without the need for a numerical lens for reconstruction. The interferometer is associated with a telescope system to feature the object with collimated light. The experiment is conducted on two objects possessing different step heights. The phase maps from the captured off-axis holograms are calculated numerically, which allows us to deduce the contours of the objects. The great advantages of the presented technique are that it can be done in real time and there is no need for numerical lenses for micro-objects reconstruction. ? 2015 Chinese Optics Letters.Accession Number: 20154801632082 -
Record 345 of
Title:The investigation of automatic exposure under extreme light
Author(s):Wang, Zefeng(1); Yang, Lei(1); Huang, Jijang(1); Zhang, Zhi(1); Xie, Qingsheng(1); Chen, Yaohong(1); Liao, Jiawen(1); Zhang, Zhaohui(1); Zhang, Haifeng(1); Zhang, Kaisheng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9449 Issue: DOI: 10.1117/12.2074827 Published: 2015Abstract:For imaging equipments, exposure is one of the crucial factors for evaluating the quality of imaging. The correct method of exposure is the key to obtain high-quality image. Traditional calculation of exposure is slow in adaptation under extreme environment. In addition, the object of imaging under extreme light usually cannot achieve suitable gray level. To obtain accurate and effective control of automatic exposure under back light and front light environment, this article divides shoot scenes into different regions, applying the method of fuzzy logic to give each region a different weight number, and finally allowing it to correctly carry out automatic exposure. This method can manage imaging under special light conditions without being affected by the position of the main object. Experiments show that this method can effectively control automatic exposure under all kinds of environments. ? 2015 SPIE.Accession Number: 20151100635571 -
Record 346 of
Title:Efficient CW dual-wavelength and passively Q-switched Tm:LuAG lasers
Author(s):Feng, Tianli(1); Yang, Kejian(1); Zhao, Shengzhi(1); Zhao, Jia(1); Qiao, Wenchao(1); Li, Tao(1); Zheng, Lihe(2); Xu, Jun(2); Wang, Qingguo(2); Xu, Xiaodong(2); Su, Liangbi(2); Wang, Yonggang(3)Source: IEEE Photonics Technology Letters Volume: 27 Issue: 1 DOI: 10.1109/LPT.2014.2357800 Published: January 1, 2015Abstract:Efficient diode-pumped Tm:LuAG lasers operating in continuous wave, dual-wavelength,and passive Q-switching regimes have been demonstrated. A maximum output power of 4.42 W with a beam quality of M2 ≤1.45 at 2021.2 nm was obtained, corresponding to a slope efficiency of 49.5%. Using a birefringent quartz plate, the Tm:LuAG laser emitted the highest output power of 2.3 W at dual-wavelength of 2022 and 2030 nm. With a SWCNT-SA employed as saturable absorber, passively Q-switched Tm:LuAG laser was realized, which generated the shortest pulses of 405 ns at 2021.6 nm and a maximum single pulse energy of 40.6 μJ at 2019.7 nm. ? 2014 IEEE.Accession Number: 20145100337444 -
Record 347 of
Title:Ionic liquids: Not only structurally but also dynamically heterogeneous
Author(s):Zheng, Zhuan-Ping(1,2); Fan, Wen-Hui(2); Roy, Soham(1,4); Mazur, Kamila(1); Nazet, Andreas(3); Buchner, Richard(3); Bonn, Mischa(1); Hunger, Johannes(1)Source: Angewandte Chemie - International Edition Volume: 54 Issue: 2 DOI: 10.1002/anie.201409136 Published: January 7, 2015Abstract:In recent years, the complex and heterogeneous structure of ionic liquids has been demonstrated; however, the consequences on the dynamics have remained elusive. Here, we use femtosecond IR spectroscopy to elucidate the local structural dynamics in protic alkylammonium-based ionic liquids. The structural relaxation after an ultrafast temperature increase, following vibrational excitation and subsequent relaxation of the N-D (or N-H) stretching vibration, is found to vary substantially between the ionic and hydrophobic subdomains. The dynamics in the ionic domains are virtually unaffected by the alkyl chain length and is, therefore, decoupled from viscosity. Equilibration within the hydrophobic subdomains, as evident from the dynamics of the C-H stretching vibration, is faster than that in the ionic domains and shows a remarkably low thermal activation. ? 2015 Wiley-VCH Verlag GmbH & Co. KGaA.Accession Number: 20150800541212 -
Record 348 of
Title:Graph-based learning for segmentation of 3D ultrasound images
Author(s):Chang, Huali(1); Chen, Zhenping(1); Huang, Qinghua(1); Shi, Jun(2); Li, Xuelong(3)Source: Neurocomputing Volume: 151 Issue: P2 DOI: 10.1016/j.neucom.2014.05.092 Published: March 5, 2015Abstract:The analysis of 3D medical images becomes necessary since the 3D imaging techniques have been more and more widely applied in medical applications. This paper introduces a novel segmentation method for extracting objects of interest (OOI) in 3D ultrasound images. In the proposed method, a bilateral filtering model is first applied to a 3D ultrasound volume data set for speckle reduction. We then take advantage of graph theory to construct a 3D graph, and merge sub-graphs into larger one during the segmentation process. Therefore, the proposed method can be called a 3D graph-based segmentation algorithm. After the mergence of sub-graphs, a set of minimum spanning trees each of which corresponds to a 3D sub-region is generated. In terms of segmentation accuracy, the experiments using an ultrasound fetus phantom, a resolution phantom and human fingers demonstrate that the proposed method outperforms the 3D Snake and Fuzzy C means clustering methods, indicating improved performance for potential clinical applications. ? 2014 Elsevier B.V.Accession Number: 20144600206211