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Record 109 of
Title:Research on an equal wavelength spectrum reconstruction method of interference imaging spectrometer
Author(s):Xie, Pei-Yue(1,2); Yang, Jian-Feng(1); Xue, Bin(1); Lü, Juan(1); He, Ying-Hong(1); Li, Ting(1); Ma, Xiao-Long(1)
Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 36 Issue: 3 DOI: 10.3964/j.issn.1000-0593(2016)03-0848-05 Published: March 1, 2016
Abstract:Interference imaging spectrometer is one of the most important equipments of Chang'E 1 satellite, which is applied to analysis the material composition and its distribution of the surface on the moon. At present, the spectral resolution of level 2B scientific data obtained by existing methods is 325 cm-1. If we use the description way of wavelength resolution, various spectrum is different: the first band is 7.6 nm, the last band is 29 nm, which introduces two questions: (1) the spectral resolution description way mismatch with the way of ground spectral library used for calibration and comparison; (2) The signal-to-noise ratio of the spectra in the shortwave band is low due to the signal entering narrow band is little. This paper discussed the relationship between wavelength resolution and cut-off function based on the reconstruction model of CE-1 interference imaging spectrometer. It proposed an adjustable cut-off function changing with wavelength or wavelength resolution, while selected the appropriate Sinc function as apodization to realize the reconstruction of arbitrary specified wavelength resolution in the band coverage. Then we used this method to CE-1 on orbit 0B data to get a spectral image of 29 nm wavelength resolution. Finally, by usingthe signal-to-noise ratio, principal component analysis and unsupervised classification method on the reconstruction results with 2 grade science data from ground application system for comparison, the results showed that: signal-to-noise ratio of the shortwave band increased about 4 times, and the average increased about 2.4 times, the classification based on the spectrum was consistent, and the quality of the data was greatly improved. So, EWSR method has the advantages that: (1) in the case of keeping spectral information steadiness,it can improve the signal-to-noise ratio of shortwave band spectrum though sacrificed part of spectral resolution; (2) it can achieve the spectral data reconstruction which can set arbitrary band position or specify any wavelength resolution within the band range. ? 2016, Peking University Press. All right reserved.
Accession Number: 20161902371723
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Record 110 of
Title:Detection and tracking of multi-space junks in star images
Author(s):Deng, Wenkang(1,2); Song, Zongxi(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10033 Issue: DOI: 10.1117/12.2244285 Published: 2016
Abstract:An algorithm of detection and tracking of multiple small moving space junks under the complex star sequential images is proposed in this paper. Firstly we take image smoothing and adaptive threshold segment to improve the weight of junks. Furthermore, back neighborhood frame correlation (BNFC) is proposed to detect and locate the junk which is sheltered by bigger interfaced stars. Through cross projection method, we could extract the centroid of the moving junks. At last, the Kalman Filter is used to track and estimate the trajectory of moving junks. Experiments show that through this algorithm the multiple small space junks could be detected and tracked effectively and accurately under complex star background with good performance in low error rate and good real-time processing. ? 2016 SPIE.
Accession Number: 20164903101480
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Record 111 of
Title:Robust Semi-Supervised Subspace Clustering via Non-Negative Low-Rank Representation
Author(s):Fang, Xiaozhao(1); Xu, Yong(1,2); Li, Xuelong(3); Lai, Zhihui(1); Wong, Wai Keung(4,5)
Source: IEEE Transactions on Cybernetics Volume: 46 Issue: 8 DOI: 10.1109/TCYB.2015.2454521 Published: August 2016
Abstract:Low-rank representation (LRR) has been successfully applied in exploring the subspace structures of data. However, in previous LRR-based semi-supervised subspace clustering methods, the label information is not used to guide the affinity matrix construction so that the affinity matrix cannot deliver strong discriminant information. Moreover, these methods cannot guarantee an overall optimum since the affinity matrix construction and subspace clustering are often independent steps. In this paper, we propose a robust semi-supervised subspace clustering method based on non-negative LRR (NNLRR) to address these problems. By combining the LRR framework and the Gaussian fields and harmonic functions method in a single optimization problem, the supervision information is explicitly incorporated to guide the affinity matrix construction and the affinity matrix construction and subspace clustering are accomplished in one step to guarantee the overall optimum. The affinity matrix is obtained by seeking a non-negative low-rank matrix that represents each sample as a linear combination of others. We also explicitly impose the sparse constraint on the affinity matrix such that the affinity matrix obtained by NNLRR is non-negative low-rank and sparse. We introduce an efficient linearized alternating direction method with adaptive penalty to solve the corresponding optimization problem. Extensive experimental results demonstrate that NNLRR is effective in semi-supervised subspace clustering and robust to different types of noise than other state-of-the-art methods. ? 2015 IEEE.
Accession Number: 20153201158194
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Record 112 of
Title:Spectral multimodal hashing and its application to multimedia retrieval
Author(s):Zhen, Yi(1); Gao, Yue(2); Yeung, Dit-Yan(3); Zha, Hongyuan(1); Li, Xuelong(4)
Source: IEEE Transactions on Cybernetics Volume: 46 Issue: 1 DOI: 10.1109/TCYB.2015.2392052 Published: January 2016
Abstract:In recent years, multimedia retrieval has sparked much research interest in the multimedia, pattern recognition, and data mining communities. Although some attempts have been made along this direction, performing fast multimodal search at very large scale still remains a major challenge in the area. While hashing-based methods have recently achieved promising successes in speeding-up large-scale similarity search, most existing methods are only designed for uni-modal data, making them unsuitable for multimodal multimedia retrieval. In this paper, we propose a new hashing-based method for fast multimodal multimedia retrieval. The method is based on spectral analysis of the correlation matrix of different modalities. We also develop an efficient algorithm that learns some parameters from the data distribution for obtaining the binary codes. We empirically compare our method with some state-of-the-art methods on two real-world multimedia data sets. ? 2015 IEEE.
Accession Number: 20153001069572
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Record 113 of
Title:Inverse sinusoidal phase mask to extend the depth of field of incoherent imaging systems
Author(s):Zhou, Liang(1,2); Liu, Zhaohui(1); She, Wenji(1); Shan, Qiusha(1)
Source: Optik Volume: 127 Issue: 20 DOI: 10.1016/j.ijleo.2016.06.131 Published: October 1, 2016
Abstract:Wavefront coding is an effective way to extend the depth of field of an incoherent imaging system. With a suitable phase mask, the defocus invariant imaging characteristic of an incoherent imaging system can be achieved. In this paper, an effective way to generate new type of phase mask is proposed. On the basis of the new method, the inverse sinusoidal phase mask is proposed to enrich the family of anti-symmetric phase masks. The performances of inverse sinusoidal phase mask are evaluated by comparisons with cubic, sinusoidal and tangent phase masks. Numerical evaluations demonstrate that the proposed phase mask has superior performance in extending the depth of field and small artifacts in restored images, particularly at large defocus. ? 2016 Elsevier GmbH
Accession Number: 20162902602933
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Record 114 of
Title:Design, fabrication, and testing of duralumin zoom mirror with variable thickness
Author(s):Hui, Zhao(1); Xie, Xiaopeng(1,2); Xu, Liang(1); Ding, Jiaoteng(1); Shen, Le(1); Liu, Meiying(1); Gong, Jie(3)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10154 Issue: DOI: 10.1117/12.2243992 Published: 2016
Abstract:Zoom mirror is a kind of active optical component that can change its curvature radius dynamically. Normally, zoom mirror is used to correct the defocus and spherical aberration caused by thermal lens effect to improve the beam quality of high power solid-state laser since that component was invented. Recently, the probable application of zoom mirror in realizing non-moving element optical zoom imaging in visible band has been paid much attention. With the help of optical leveraging effect, the slightly changed local optical power caused by curvature variation of zoom mirror could be amplified to generate a great alteration of system focal length without moving elements involved in, but in this application the shorter working wavelength and higher surface figure accuracy requirement make the design and fabrication of such a zoom mirror more difficult. Therefore, the key to realize non-moving element optical zoom imaging in visible band lies in zoom mirror which could provide a large enough saggitus variation while still maintaining a high enough surface figure. Although the annular force based actuation could deform a super-Thin mirror having a constant thickness to generate curvature variation, it is quite difficult to maintain a high enough surface figure accuracy and this phenomenon becomes even worse when the diameter and the radius-Thickness ratio become bigger. In this manuscript, by combing the pressurization based actuation with a variable thickness mirror design, the purpose of obtaining large saggitus variation and maintaining quite good surface figure accuracy at the same time could be achieved. A prototype zoom mirror with diameter of 120mm and central thickness of 8mm is designed, fabricated and tested. Experimental results demonstrate that the zoom mirror having an initial surface figure accuracy superior to 1/50λ could provide at least 21um saggitus variation and after finishing the curvature variation its surface figure accuracy could still be superior to 1/20λ, which proves that the effectiveness of the theoretical design. ? 2016 SPIE.
Accession Number: 20170503310055
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Record 115 of
Title:Optical design of visible and infrared integrative camera
Author(s):Li, Ruichang(1,2); Zou, Gangyi(1,2); Wang, Chenchen(1,2); Fan, Xuewu(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 36 Issue: 5 DOI: 10.3788/AOS201636.0522002 Published: May 10, 2016
Abstract:The spatial resolution, time resolution and spectral resolution of the space remote sensing camera are improved gradually, the spectral band for observation of the camera is also extended and the multispectral observation is realized. The design of visible and infrared integrative optical system is studied based on the need of multispectral observation. The design is accomplished through calculation and an optical design software. In this design, the system focal length of the visible part is 6000 mm, F number is 11.8 and the wavelength band is 400~900 nm. The system focal length of the infrared part is 1280 mm, F number is 2.5 and the wavelength band is 3000~5000 nm. The field of view is 1.4°×0.6° for both of the systems. The visible band system and the infrared band system share the first four mirrors, the fifth is a dichroic mirror and reflects the visible light to the time delayed and integration CCD which is over the fifth mirror. The infrared light passes through the fifth mirror to the rear lens set for correction. The whole system has no color aberration, its structure is compact, and the image quality for visible and infrared is up to par. ? 2016, Chinese Lasers Press. All right reserved.
Accession Number: 20162102427160
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Record 116 of
Title:Interference data correction methods for lunar observation with a large-aperture static imaging spectrometer
Author(s):Zhang, Geng(1); Wang, Shuang(1); Li, Libo(1); Hu, Xiuqing(2); Hu, Bingliang(1)
Source: Applied Optics Volume: 55 Issue: 31 DOI: 10.1364/AO.55.008770 Published: November 1, 2016
Abstract:The lunar spectrum has been used in radiometric calibration and sensor stability monitoring for spaceborne optical sensors. A ground-based large-aperture static image spectrometer (LASIS) can be used to acquire the lunar spectral image for lunar radiance model improvement when the moon orbits over its viewing field. The lunar orbiting behavior is not consistent with the desired scanning speed and direction of LASIS. To correctly extract interferograms from the obtained data, a translation correction method based on image correlation is proposed. This method registers the frames to a reference frame to reduce accumulative errors. Furthermore, we propose a circle-matching-based approach to achieve even higher accuracy during observation of the full moon. To demonstrate the effectiveness of our approaches, experiments are run on true lunar observation data. The results show that the proposed approaches outperform the state-of-the-art methods. ? 2016 Optical Society of America.
Accession Number: 20164603017440
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Record 117 of
Title:Effect of different parameters on machining of SiC/SiC composites via pico-second laser
Author(s):Li, Weinan(1); Zhang, Ruoheng(1); Liu, Yongsheng(2); Wang, Chunhui(2); Wang, Jing(2); Yang, Xiaojun(1); Cheng, Laifei(2)
Source: Applied Surface Science Volume: 364 Issue: DOI: 10.1016/j.apsusc.2015.12.089 Published: February 28, 2016
Abstract:Pico-second laser plays an important role in modern machining technology, especially in machining high hardness materials. In this article, pico-second laser was utilized for irradiation on SiC/SiC composites, and effects of different processing parameters including the machining modes and laser power were discussed in detail. The results indicated that the machining modes and laser power had great effect on machining of SiC/SiC composites. Different types of surface morphology and structure were observed under helical line scanning and single ring line scanning, and the analysis of their formulation was discussed in detail. It was believed that the machining modes would be responsible to the different shapes of machining results at the same parameters. The processing power shall also influence the surface morphology and quality of machining results. In micro-hole drilling process, large amount of debris and fragments were observed within the micro-holes, and XPS analysis showed that there existed Si-O bonds and Si-C bonds, indicating that the oxidation during processing was incomplete. Other surface morphology, such as pores and pits were discussed as well. ? 2015 Elsevier B.V. All rights reserved.
Accession Number: 20161702289255
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Record 118 of
Title:Characteristics of the orbital rotation in dual-beam fiber-optic trap with transverse offset
Author(s):Chen, Xinlin(1); Xiao, Guangzong(1,2); Yang, Kaiyong(1); Xiong, Wei(1); Luo, Hui(1)
Source: Optics Express Volume: 24 Issue: 15 DOI: 10.1364/OE.24.016952 Published: July 25, 2016
Abstract:The orbital rotation is an important type of motion of trapped particles apart from translation and spin rotation. It could be realized by introducing a transverse offset to the dual-beam fiber-optic trap. The characteristics (e.g. rotation perimeter and frequency) of the orbital rotation have been analyzed in this article. We demonstrate the influences of offset distance, beam waist separation distance, light power, and radius of the microsphere by both experimental and numerical work. The experiment results, i.e. orbital rotation perimeter and frequency as functions of these parameters, are consistent with the theoretical model in the present work. The orbital rotation amplitude and frequency could be exactly controlled by varying these parameters. This controllable orbital rotation can be easily applied to the area where microfluidic mixing is required. ?2016 Optical Society of America.
Accession Number: 20163102656274
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Record 119 of
Title:Pressurization actuation based variable curvature mirror having variable thickness
Author(s):Zhao, Hui(1); Xie, Xiao-Peng(1,2); Xu, Liang(1); Ding, Jiao-Teng(1); Liu, Mei-Ying(1); Fan, Xue-Wu(1)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 45 Issue: 11 DOI: 10.3788/gzxb20164511.1122001 Published: November 1, 2016
Abstract:Based on the model of annular force based actuation, the reasons why it is hard for annular force based variable curvature mirror to obtain a large saggitus variation and maintain a high-accuracy surface figure simultaneously were analyzed. From the elasticity theory of thin plate, a physical model of variable curvature mirror in which pressurization actuation and variable thickness design are combined together was proposed. The theoretical analysis results show that, by making the mirror thickness be variable from the center to the periphery portion and adopting the pressurization actuation, the large saggitus variation can be obtained while the surface figure accuracy can be maintained and higher than the annular line load variable curvature mirror. A duralumin prototype mirror was designed, fabricated and tested. The surface figure accuracy of the mirror before curvature variation is superior to λ/50 (632.8 nm). When a pressure of about 0.032 MPa is imposed, the mirror can provide a saggitus variation exceeding 22 μm and at the same the corresponding surface figure accuracy is still superior to λ/20 (632.8 nm), which verifies the theoretical analysis about variable thickness mirror and proves that the design combination integrating pressurization actuation and variable mirror thickness is a promising technical way to construct an applicable variable curvature mirror. ? 2016, Science Press. All right reserved.
Accession Number: 20164703047424
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Record 120 of
Title:Dynamics analysis of microsphere in a dualbeam fiber-optic trap with transverse offset
Author(s):Chen, Xinlin(1); Xiao, Guangzong(1,2); Luo, Hui(1); Xiong, Wei(1); Yang, Kaiyong(1)
Source: Optics Express Volume: 24 Issue: 7 DOI: 10.1364/OE.24.007575 Published: April 4, 2016
Abstract:A comprehensive dynamics analysis of microsphere has been presented in a dual-beam fiber-optic trap with transverse offset. As the offset distance between two counterpropagating beams increases, the motion type of the microsphere starts with capture, then spiral motion, then orbital rotation, and ends with escape. We analyze the transformation process and mechanism of the four motion types based on ray optics approximation. Dynamic simulations show that the existence of critical offset distances at which different motion types transform. The result is an important step toward explaining physical phenomena in a dual-beam fiberoptic trap with transverse offset, and is generally applicable to achieving controllable motions of microspheres in integrated systems, such as microfluidic systems and lab-on-a-chip systems. ? 2016 Optical Society of America.
Accession Number: 20161802330692
