2016

• Record 385 of
  
  Title:A new spectral-spatial algorithm method for hyperspectral image target detection
  
  Author(s):Wang, Cai-Ling(1,2); Wang, Hong-Wei(3); Hu, Bing-Liang(1); Wen, Jia(4); Xu, Jun(5); Li, Xiang-Juan(2)
  Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis  Volume: 36  Issue: 4  DOI: 10.3964/j.issn.1000-0593(2016)04-1163-07  Published: April 1, 2016  
  Abstract:With high-resolution spatial information and continuous spectrum information, hyperspectral remote sensing image -has a unique advantage in the field of target detection. Traditional hyperspectral remote sensing image target detection methods emphasis on using spectral information to determine deterministic algorithm and statistical algorithms. Deterministic algorithms find the target by calculating the distance between the target spectrum and detected spectrum however, they are unable to detect sub-pixel target and are easily affected by noise. Statistical methods which calculate background statistical characteristics to detect abnormal point as target. It can detect subpixel target targets and small targets better thanbig size target,. With the spatial resolution increasing, subpixel target detection target has gradually grown to a single pixel and multi-pixel target. At this point, hyperspectral image usually has large homogeneous regions where the neighboring pixels wihin the regions consist of the same type of materials and have a similar spectral characteristics, therefore, the spatial information should be needed to incorporate into the algorithm for targe detection. This paper proposes an algorithm for hyperspectral target detection combined spectrum characteristics and spatial characteristics. The algorithm is based on traditional target detection operator and combined neighborhood clustering statistics. Firstly, the algorithm uses target detection operator to divided hyperspectral image into a potential target region and background region. Then, it calculates the centroid of the potential target area. Finally, as the centroid for neighborhood clustering center to clust data in order to exclud background from potential target area, through iterative calculation to obtain the final results of the target detection. The traditional statistics algorithms defines the total image as background area in order to extract background statistics features, and the algorithm propsed devided the total image into background part and potential target part, which cut off the target interference for background statistics feature extraction. Compared with CEM operators and ACE operators, the algorithm proposed outperforms than traditional operators in big target detection. © 2016, Peking University Press. All right reserved.
  Accession Number: 20161902371775
• Record 386 of
  
  Title:Temporal distortion analysis of the streak tube
  
  Author(s):Hui, Dan-Dan(1,2,3); Tian, Jin-Shou(1,3); Lu, Yu(1); Wang, Jun-Feng(1); Wen, Wen-Long(1); Liang, Ling-Liang(1,2); Chen, Lin(1,2)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 65  Issue: 15  DOI: 10.7498/aps.65.158502  Published: August 5, 2016  
  Abstract:Streak cameras applied to inertial confinement fusion research and flashless imaging lidar require large working areas. However, the larger the working area, the bigger the temporal distortion is. And the temporal distortion has a great influence on the detecting precision of the streak camera, resulting in an image distortion on the screen. Yet previous streak camera design work emphasized shorter time resolution and higher special resolution with paying less attention to the temporal distortion extent. Key factors that may affect the temporal distortion are thoroughly analyzed in this paper. We calculate the electric field of a small-size streak tube with the aid of the Computer Simulation Technology Particle Studio software which is a three-dimensional electromagnetic simulation software based on finite integration technology. Axial electric field distributions at different distances to the axis of the small-size streak tube are displayed. The electron trajectories launched from different points on photocathode of the streak tube are tracked through interpolating precalculated electromagnetic field to the particle position. It is known that curved photocathode can reduce the temporal distortion, so we calculate the temporal distortions of streak tubes whose radii of curvature of the photocathode are 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, and 55 mm respectively to ascertain how the curvature influences the temporal distortion. The results show that the temporal distortion is mainly produced in the photocathode-to-deflector region, and it is negligible in the equipotential region. Also, bigger radius of curvature of the photocathode leads to a positive temporal distortion, and smaller one leads to a negative temporal distortion. And the absolute value of the temporal distortion increases with the increase of the slit length. The small-size streak tube whose radius of curvature of the photocathode is 40 mm owns the smallest temporal distortion. We also calculate the temporal distortions of electrons launched from the different positions of the photocathode with different initial energies, and the initial energy has little influence on the temporal distortion. To sum up, the dominating factor that produces the temporal distortion is the curvature of the photocathode. The slit image under a ramp sweeping voltage on screen is curved due to the temporal distortion. And the bigger the temporal distortion, the greater the curvature of the slit image is. Besides, a linear relation between the temporal distortion and deflection of the slit image is displayed. The spatial resolutions of the streak tubes with the radii of curvature of the photocathode 30 mm, 40 mm, 50 mm are calculated respectively. And the small-size streak tube whose radius of curvature of the photocathode is 30 mm has the highest spatial resolution. The radius of curvature of the streak tube photocathode should be carefully selected according to actual requirements for the streak camera. Through the analysis we provide a significant guidance for streak tube design. © 2016 Chinese Physical Society.
  Accession Number: 20163202703774
• Record 387 of
  
  Title:Deblurring for spatial and temporal varying motion with optical computing
  
  Author(s):Xiao, Xiao(1,2); Xue, Dongfeng(2); Hui, Zhao(3)
  Source: Optical Engineering  Volume: 55  Issue: 5  DOI: 10.1117/1.OE.55.5.053103  Published: May 1, 2016  
  Abstract:A way to estimate and remove spatially and temporally varying motion blur is proposed, which is based on an optical computing system. The translation and rotation motion can be independently estimated from the joint transform correlator (JTC) system without iterative optimization. The inspiration comes from the fact that the JTC system is immune to rotation motion in a Cartesian coordinate system. The work scheme of the JTC system is designed to keep switching between the Cartesian coordinate system and polar coordinate system in different time intervals with the ping-pang handover. In the ping interval, the JTC system works in the Cartesian coordinate system to obtain a translation motion vector with optical computing speed. In the pang interval, the JTC system works in the polar coordinate system. The rotation motion is transformed to the translation motion through coordinate transformation. Then the rotation motion vector can also be obtained from JTC instantaneously. To deal with continuous spatially variant motion blur, submotion vectors based on the projective motion path blur model are proposed. The submotion vectors model is more effective and accurate at modeling spatially variant motion blur than conventional methods. The simulation and real experiment results demonstrate its overall effectiveness. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).
  Accession Number: 20162402492242
• Record 388 of
  
  Title:Simulation of the effects of coated material SEY property on output electron energy distribution and gain of microchannel plates
  
  Author(s):Chen, Lin(1,2,4); Wang, Xingchao(3); Tian, Jinshou(1,5); Liu, Chunliang(4); Liu, Hulin(1); Chen, Ping(1,2); Wei, Yonglin(1); Sai, Xiaofeng(1); Sun, Jianning(3); Si, Shuguang(3); Wang, Xing(1); Lu, Yu(1); Tian, Liping(1,2); Hui, Dandan(1,2); Guo, Lehui(1,2)
  Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment  Volume: 840  Issue:   DOI: 10.1016/j.nima.2016.10.014  Published: December 21, 2016  
  Abstract:To obtain a high spatial resolution of a image intensifier based on microchannel plate (MCP), the long tail in the exit energy distribution of the output electrons (EDOE) is undesirable. The existing solution is increasing the penetration depth of the MCP output electrode, which will result in a serious gain reduction. Coating the MCP output electrode with efficient secondary electron yield (SEY) materials is supposed to be an effective approach to suppress the unfavorable tail component in the EDOE without negative effects on the gain. In our work, a three-dimensional MCP single channel model is developed in CST STUDIO SUITE to systematically investigate the dependences of the EDOE and the gain on the SEY property of the coated material, based on the Finite Integral Technique and Monte Carlo method. The results show that besides the high SEY of the coated material, the low incident energy corresponding to the peak SEY is another essential element affecting the electron yield in the final stage of multiplication and suppressing the output energy spread. © 2016 Elsevier B.V.
  Accession Number: 20164302937814
• Record 389 of
  
  Title:Research on dynamic tracking and compensation method for hyperspectral interference imaging
  
  Author(s):Yu, Tao(1,2); Hu, Bing-Liang(1); Gao, Xiao-Hui(1); Wei, Ru-Yi(1); Jing, Juan-Juan(3); Hou, Xiao-Hua(1)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 45  Issue: 7  DOI: 10.3788/gzxb20164507.0710003  Published: July 1, 2016  
  Abstract:Combining the compensation corrections based on target dynamic tracking with the spectra extraction based on non-uniform fast Fourier transform, a method was proposed to realize the high precision correction of airborne remote sensing. Through the way of real-time attitude measuring, active correction, feedback compensation from position and orientation system under poor imaging condition of non-stable platform, the interferogram was obtained. The fused image and the spectral curves were obtained from the corrected interferogram by the spatial transformation and data extraction of non-uniformity. The results of airborne flight experiment show that the multi-spectral fusion image has a good quality, and the precision of spectrum recovery has been improved greatly compared with the traditional methods. The attitude measuing system based on the proposed method has a good environmental adaptability of airborne, which can be used not only for the poor stability platform but also for the other spectral imaging detection system besides the principle of interference spectroscopy imaging. The proposed method provides a way for the movement error correction of airborne integration hyperspectral image processing platform. © 2016, Science Press. All right reserved.
  Accession Number: 20163102668061
• Record 390 of
  
  Title:The R&D of the 20 in. MCP-PMTs for JUNO
  
  Author(s):Chang, Yaping(1,2,3); Huang, Guorui(4); Heng, Yuekun(1,2); Li, Dong(4); Liu, Huilin(5); Liu, Shulin(1,2); Li, Weihua(5); Ning, Zhe(1,2); Qi, Ming(6); Qian, Sen(1,2); Sun, Jianning(4); Si, Shuguang(4); Tian, Jinshou(5); Wang, Xingchao(4); Wang, Xing(5); Wang, Yifang(1,2); Wei, Yonglin(5); Wang, Wenwen(6); Xia, Jingkai(1,2,3); Xin, Liwei(5); Zhao, Tianchi(1)
  Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment  Volume: 824  Issue:   DOI: 10.1016/j.nima.2015.10.106  Published: July 11, 2016  
  Abstract:A new concept of large area photomultiplier based on MCPs was conceived for JUNO by the scientists in IHEP, and with the collaborative work of the MCP-PMT collaboration in China, 8 in. and 20 in. prototypes were produced. Test results show that this type of MCP-PMT can have good SPE performance as the traditional dynode type PMTs. © 2015 Elsevier B.V.
  Accession Number: 20154701596008
• Record 391 of
  
  Title:Experimental study on three-dimensional ptychography for thick sample
  
  Author(s):Pan, An(1,3); Zhang, Xiao-Fei(2,3); Wang, Bin(2,3); Zhao, Qing(1,3); Shi, Yi-Shi(3,4)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 65  Issue: 1  DOI: 10.7498/aps.65.014204  Published: January 5, 2016  
  Abstract:Ptychography is a new kind of lens-less imaging technology. What restricts the technique is the assumption of a multiplicative interaction between the illuminating coherent beam and the specimen, i.e., and the ptychography cannot be applied to samples no thicker than a few tens of micrometers in the case of visible-light imaging at micron-scale resolution. In the present work, we split a sample into axial sections, thereby realize three-dimensional ptychographic imaging of thick samples at the millimeter level in a series of computer simulations and optical experiments. Our simulation results reveal that by using single wavelength we cannot achieve good-quality images of thick samples. Thus it is necessary to introduce more wavelengths for illumination. With increasing the number of wavelengths, the imaging quality of three-dimensional thick samples can be enhanced continually. Then we make further study on the relationship between the imaging quality and the magnitude of wavelength in optical experiments by using two groups of samples with different thickness values. The results demonstrate that our experimental results are highly consistent with simulations. For our concrete configuration in this paper, the best results of imaging and separation may be obtained for the case of tri-wavelength. At the same time we make a reasonable explanation for the phenomenon of fold-over in the experiment. Our results are important and meaningful for the practical utilizing of three-dimensional ptychography of thick samples. © 2016 Chinese Physical Society.
  Accession Number: 20160601889260
• Record 392 of
  
  Title:SERS activity with tenfold detection limit optimization on a type of nanoporous AAO-based complex multilayer substrate
  
  Author(s):Sui, Chaofan(1,2); Wang, Kaige(1,2); Wang, Shuang(1,2); Ren, Junying(1); Bai, Xiaohong(3); Bai, Jintao(1,2)
  Source: Nanoscale  Volume: 8  Issue: 11  DOI: 10.1039/c5nr06771e  Published: March 21, 2016  
  Abstract:Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 107) and detection limit (10-10 M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm-1 in 5 × 5 μm2 area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the electromagnetic field distribution. In addition, this SERS substrate is proposed for applications within the field of chemical and biochemical analyses. © 2016 The Royal Society of Chemistry.
  Accession Number: 20161202119096
• Record 393 of
  
  Title:Optimization of the 3-inch photomultiplier tube for the neutrino detection
  
  Author(s):Guo, Le-Hui(1,2,4); Tian, Jin-Shou(1,4); Lu, Yu(1); Li, Hong-Wei(3)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 65  Issue: 22  DOI: 10.7498/aps.65.228501  Published: November 20, 2016  
  Abstract:Photomultiplier tubes (PMTs) widely used in neutrino detectors are critical to reconstructing the direction of the neutrino accurately. Large photocathode coverage, compact design and good time properties for single-photoelectron light are essential performances to meet the requirements for the next generation detectors. Therefore, a novel digital optical module housing 31 3-inch. diameter PMTs is developed. In order to maximize the effective photocathode area and improve the time performance, a modified PMT with a larger photocathode area and 10 dynodes is optimized with the aid of the CST Particle Studio in this paper. Based on the Monte Carlo method and finite integration theory, the main characteristics of the modified PMT, such as uniformity, collection efficiency, gain and transit-time spread, are investigated. As the earlier stages of the PMT contribute the greatest weight to the total transit time spread, the transit time spread of single-photoelectron from photocathode to the first dynode (TTSCD1) is discussed mainly in this paper. The influences of the dynodes position on collection efficiency and TTSCD1 are analyzed. The voltage ratio scheme is also optimized slightly to obtain better collection efficiency and minimum TTSCD1. By tracing the trajectories of secondary electrons from the first to the second dynode stage, dynodes are optimized for improving timing performance and secondary electrons collection efficiency. Direct collection efficiency of secondary electrons from the first dynode to the second is improved from 56.38% to 61.01%. The effective photocathode diameter of the modified PMT is increased from traditional 72 mm to 77.5 mm and the effective area of photocathode is increased by 30.87% compared with the traditional one. What is more, the length of the new PMT is reduced to 103 mm so that the available space of the multi-PMT digital optical module is increased by 63.09% compared with the traditional one containing the high-voltage power supplies, front-end and readout electronics, refrigerating equipment, etc. The simulation results show that the mean collection efficiency of the modified PMT is ~96.40% with the supply voltage of 1000 V and it changes little by changing the supply voltage from 900 V to 1300 V. The mean transit time spread from photocathode to the first dynode is ~1 ns which is better than the transit time spread of the traditional model. And the gain can reach above 106 with a supply voltage of above 1100 V. © 2016 Chinese Physical Society.
  Accession Number: 20164903093350
• Record 394 of
  
  Title:Aging behavior of large area MCP-PMT
  
  Author(s):Wang, Wen-Wen(1,3); Qian, Sen(1,2,3); Wang, Xing(6); Qi, Ming(1); Xia, Jing-Kai(2,3,4); Cheng, Ya-Ping(2,3,4); Ning, Zhe(2,3); Heng, Yue-Kun(2,3); Liu, Shu-Lin(2,3); Si, Shu-Guang(5); Sun, Jian-Ning(5); Li, Dong(5); Wang, Xing-Chao(5); Huang, Guo-Rui(5); Tian, Jing-Shou(6); Wei, Yong-Lin(6); Liu, Hu-Lin(6); Li, Wei-Hua(6); Xin, Li-Wei(6)
  Source: Nuclear Science and Techniques  Volume: 27  Issue: 2  DOI: 10.1007/s41365-016-0046-1  Published: April 15, 2016  
  Abstract:The Institute of High Energy Physics, Chinese Academy of Sciences have designed a new type of photomultiplier tube (PMT) based on microchannel plates (MCPs) with large area photocathode, known as large area microchannel plate photomultiplier tube (MCP-PMT). The aging characteristics of the large area MCP-PMTs are different from dynode PMTs and small proximity-focus MCP-PMT. In this work, a prototype large area MCP-PMT was aged by operating with nearly 1000 photoelectrons per pulse for 3 months, and aging process of the MCP-PMT was discussed based on the aging curve. © Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Science+Business Media Singapore 2016.
  Accession Number: 20210309795569
• Record 395 of
  
  Title:Video Supervoxels Using Partially Absorbing Random Walks
  
  Author(s):Liang, Yuling(1); Shen, Jianbing(1); Dong, Xingping(1); Sun, Hanqiu(2); Li, Xuelong(3)
  Source: IEEE Transactions on Circuits and Systems for Video Technology  Volume: 26  Issue: 5  DOI: 10.1109/TCSVT.2015.2406232  Published: May 2016  
  Abstract:Supervoxels have been widely used as a preprocessing step to exploit object boundaries to improve the performance of video processing tasks. However, most of the traditional supervoxel algorithms do not perform well in regions with complex textures or weak boundaries. These methods may generate supervoxels with overlapping boundaries. In this paper, we present the novel video supervoxel generation algorithm using partially absorbing random walks to get more accurate supervoxels in these regions. Our spatial-temporal framework is introduced by making full use of the appearance and motion cues, which effectively exploits the temporal consistency in video sequence. Moreover, we build a novel Laplacian optimization structure using two adjacent frames to make our approach more efficient. Experimental results demonstrated that our method achieved better performance than the state-of-the-art supervoxel algorithms. © 2015 IEEE.
  Accession Number: 20162202437033
• Record 396 of
  
  Title:3D object hiding using three-dimensional ptychography
  
  Author(s):Zhang, Jun(1); Wang, Zhibo(2); Li, Tuo(1); Pan, An(4); Wang, Yali(1,3); Shi, Yishi(1,3)
  Source: Journal of Optics (United Kingdom)  Volume: 18  Issue: 9  DOI: 10.1088/2040-8978/18/9/095701  Published: September 2016  
  Abstract:We present a novel technique for 3D object hiding by applying three-dimensional ptychography. Compared with 3D information hiding based on holography, the proposed ptychography-based hiding technique is easier to implement, because the reference beam and high-precision interferometric optical setup are not required. The acquisition of the 3D object and the ptychographic encoding process are performed optically. Owing to the introduction of probe keys, the security of the ptychography-based hiding system is significantly enhanced. A series of experiments and simulations demonstrate the feasibility and imperceptibility of the proposed method. © 2016 IOP Publishing Ltd.
  Accession Number: 20163902841242