2014
2014
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Record 121 of
Title:An alignment method of off-axis aspheric mirror
Author(s):Han, Juan(1,2); Duan, Jiayou(1); Chen, Jianjun(1,3); Wu, Mengyuan(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: DOI: 10.3788/AOS201434.s122002 Published: September 10, 2014Abstract:In order to realize the accurate position of an off-axis aspheric surface in optical alignment, it is necessary to strictly control the six degrees of freedom, especially the two degrees of freedom that affect lateral displacement and tilts angle. But it's very difficult to obtain the above two accurate values using general off-axis aspheric surface measurement technique, so it's same difficult to realize its precise alignment. The article introduces a new method that applying the close relationship between the center image of radius of curvature and the optical axis of the self-regulating instrument, and by using the precise measurement, the purpose of measuring lateral displacement and tilts angle is achieved. Experiments show that the error of lateral displacement is less than 0.05 mm, the error of tilts angle is less than 10″, and the wave aberration root mean square is equal to 0.02λ (λ=632.8 nm). It can obtain the perfect image and realize the precise alignment of the off-axis aspheric mirror by using this method.Accession Number: 20144100087849 -
Record 122 of
Title:Passively Q-switched lasers at 1.06 μm with graphene oxide and carbon nanotubes D2O dispersion
Author(s):Feng, Tianli(1); Zhao, Shengzhi(1); Yang, Kejian(1); Zhao, Jia(1); Li, Guiqiu(1); Li, Dechun(1); Qiao, Wenchao(1); Li, Tao(1); Chen, Xintian(1); Liu, Cheng(1); Wang, Yonggang(2)Source: Optical Materials Volume: 36 Issue: 7 DOI: 10.1016/j.optmat.2014.03.014 Published: May 2014Abstract:We have investigated the passive Q-switching characteristics of graphene oxide (GO) and single walled carbon nanotubes (SWCNTs) D2O (heavy water, deuteroxide) based on a diode-pumped YVO4/Nd:YVO4 laser for the first time as far as we know. By using 20 mg/10 ml GO D 2O dispersion, pulses with minimum duration of 344 ns under a repetition rate of 550 kHz were obtained. With 0.3 mg/10 ml SWCNTs D 2O dispersion, a maximum pulse energy of 1.2 μJ with duration of 530 ns was achieved at a repetition rate of 178 kHz. ? 2014 Elsevier B.V. All rights reserved.Accession Number: 20141717612107 -
Record 123 of
Title:Sparse frontal face image synthesis from an arbitrary profile image
Author(s):Zhao, Lin(1); Gao, Xinbo(1); Yuan, Yuan(2); Tao, Dapeng(3)Source: Neurocomputing Volume: 128 Issue: DOI: 10.1016/j.neucom.2013.08.018 Published: March 27, 2014Abstract:Frontal face image synthesis from an arbitrary profile image plays an important role in automatic video surveillance systems, and remains a challenge in computer vision. The strategies of partition are popular and promising for synthesizing frontal face images. However, conventional rectangular partition criterions fail to align corresponding patches in profile images and frontal face images. Given an arbitrary profile image, to synthesize a corresponding frontal face image which is smooth in texture and similar in appearance, we introduce a triangulation-based partition criterion and do synthesis based on sparse representation. The triangulation-based partition ensures the corresponding triangular patches are strictly aligned. And sparse representation adaptively finds the most similar patches for synthesis while abandons unlike patches. Furthermore, a confederate learning strategy is proposed to reduce the blocking artifacts caused by triangulation-based partition. Experimental results conducted on the Oriental Face database demonstrate the effectiveness of the proposed frontal face image synthesis method and advantages over previous works. ? 2013 Elsevier B.V.Accession Number: 20140517261366 -
Record 124 of
Title:An adaptive wavelet transformation used on interference hyperspectral image compression
Author(s):Wen, Jia(1,2); Ma, Caiwen(2); Zhao, Junsuo(1); Wang, Cailing(3)Source: Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology Volume: 46 Issue: 7 DOI: Published: July 30, 2014Abstract:To get better performance of interference hyperspectral image compression, according to the imaging principle ofinterference hyperspectral image, we propose an adaptive direction prediction wavelet transform forLWT (Lifting Wavelet Transformation), to get the best predicted values through adaptive direction in the LWT on the frame direction, and change the order of the traditional wavelet transform. The experiment results prove that the proposed method can get higher SNR at the same bpppb compared with the traditional method, and can get smaller MSE in the recovered spectral curve.Accession Number: 20144500160817 -
Record 125 of
Title:Tunable wavefront coded imaging system based on detachable phase mask: Mathematical analysis, optimization and underlying applications
Author(s):Zhao, Hui(1); Wei, Jingxuan(2)Source: Optics Communications Volume: 326 Issue: DOI: 10.1016/j.optcom.2014.04.023 Published: September 1, 2014Abstract:The key to the concept of tunable wavefront coding lies in detachable phase masks. Ojeda-Castaneda et al. (Progress in Electronics Research Symposium Proceedings, Cambridge, USA, July 5-8, 2010) described a typical design in which two components with cosinusoidal phase variation operate together to make defocus sensitivity tunable. The present study proposes an improved design and makes three contributions: (1) A mathematical derivation based on the stationary phase method explains why the detachable phase mask of Ojeda-Castaneda et al. tunes the defocus sensitivity. (2) The mathematical derivations show that the effective bandwidth wavefront coded imaging system is also tunable by making each component of the detachable phase mask move asymmetrically. An improved Fisher information-based optimization procedure was also designed to ascertain the optimal mask parameters corresponding to specific bandwidth. (3) Possible applications of the tunable bandwidth are demonstrated by simulated imaging. ? 2014 Elsevier B.V.Accession Number: 20141917693600 -
Record 126 of
Title:Design of dual band imaging system for space debris
Author(s):Wang, Hu(1,2); Luo, Jianjun(1); Lu, Xin(3); Li, Chunyan(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9281 Issue: DOI: 10.1117/12.2068442 Published: 2014Abstract:In order to detect the space debris, a dual band imaging system for space debris was proposed. The dual band imaging system was consisted of visible imaging system and long-wave imaging system. The dual band imaging system used the primary mirror and secondary mirror together, including correction lens in every imaging system in order to balance aberration. The focal length was 1000 mm and field of view was 1. 2° for visible imaging system, and the focal length was 250 mm and field of view was 2.75° for LWIR imaging system. Some measures were taken to make sure the less degradation of MTF for thermal distortion, such as a kind of material with good thermal property as mirror substrate to reduce surface distortion. The modulation transfer function (MTF) of dual band imaging system in condition of 20± 5°C was analyzed, which showed a good result for user's requirement. ? 2014 SPIE.Accession Number: 20153101080903 -
Record 127 of
Title:Contrast transfer function in grating-based x-ray phase-contrast imaging
Author(s):Huang, Jianheng(1); Du, Yang(1,2); Lin, Danying(1); Liu, Xin(1); Niu, Hanben(1)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 747 Issue: DOI: 10.1016/j.nima.2014.01.029 Published: May 21, 2014Abstract:x-Ray grating interferometry is a method for x-ray wave front sensing and phase-contrast imaging that has been developed over past few years. Contrast and resolution are the criteria used to specify the quality of an image. In characterizing the performance of this interferometer, the contrast transfer function is considered in this paper. The oscillatory nature of the contrast transfer function (CTF) is derived and quantified for this interferometer. The illumination source and digital detector are both considered as significant factors controlling image quality, and it can be noted that contrast and resolution in turn depends primarily on the projected intensity profile of the array source and the pixel size of the detector. Furthermore, a test pattern phantom with a well-controlled range of spatial frequencies was designed and imaging of this phantom was simulated by a computer. Contrast transfer function behavior observed in the simulated image is consistent with our theoretical CTF. This might be beneficial for the evaluation and optimization of a grating-based x-ray phase contrast imaging system. ? 2014 Published by Elsevier B.V.Accession Number: 20141117450473 -
Record 128 of
Title:Laser induced self-propagating reduction and exfoliation of graphite oxide as an electrode material for supercapacitors
Author(s):Wang, Dewei(1); Min, Yonggang(1); Yu, Youhai(1); Peng, Bo(1)Source: Electrochimica Acta Volume: 141 Issue: DOI: 10.1016/j.electacta.2014.07.036 Published: September 20, 2014Abstract:Focused laser beam induced self-propagating reaction has been developed for fabrication of graphene rapidly and efficiently through simultaneous reduction and exfoliation of graphite oxide (GO) process. This chemical-free approach can realize the reduction and exfoliation at room temperature without assistance of any high temperature/vacuum environment. We found that the small sized spot can trigger an ultrafast and highly thermal transferred process by self-propagating reaction at ambient conditions. Benefiting from its high surface area and unique structure, the laser induced self-propagating reaction reduced graphene (LIG) shows excellent capacitive performance. Considering that the cost-effective and feasible process, this facile technique presented here will not only provide a promising method for production of graphene on an industrial scale, but also put forward the application graphene materials in energy storage and conversion. ? 2014 Elsevier Ltd.Accession Number: 20143418092644 -
Record 129 of
Title:Image quality evaluation and analysis in Fourier telescopy for laboratory demonstration
Author(s):Zhang, Yu(1,2); Luo, Xiu-Juan(1); Xia, Ai-Li(1); Cao, Bei(1); Cheng, Zhi-Yuan(1,2); Zeng, Zhi-Hong(1,2); Si, Qing-Dan(1,2); Wang, Bao-Feng(1,2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 3 DOI: 10.3788/gzxb20144303.0311001 Published: March 2014Abstract:Strehl ratio is often used as a method for evaluation of the Fourier telescope imaging quality. This method computes the correlation of the reconstructed image and the ideal image to evaluate the image quality, which is mainly applicable in the computer simulation analysis. However, the object to be observed may be unknow in the real world, which means there is no ideal image for use. Based on laboratory imaging data, the feasibility of the non-reference image evaluation method applied to Fourier telescopy is proposed and analyzed. The gray mean grads (GMG) method and Laplacian Sum(LS) are adopted to describe how much detail information the reconstructed image has. For the same object, Employ Strehl ratio and GMG, LS to evaluate the simulated image and the laboratory imaging result, respectively. Statistical results show that the two kinds of evaluations are identical in changing tendency. It proves the GMG and LS methods are applicable in Fourier telescopy as a non-reference image evaluation.Accession Number: 20141717623311 -
Record 130 of
Title:Efficient closed-loop multiple-view registration
Author(s):Shao, Xiaowei(1,2); Shi, Yun(3,4); Zhao, Huijing(5); Li, Xuelong(6); Shibasaki, Ryosuke(4)Source: IEEE Transactions on Intelligent Transportation Systems Volume: 15 Issue: 6 DOI: 10.1109/TITS.2014.2319352 Published: December 1, 2014Abstract:Registering multiple views is an essential and challenging problem for many intelligent transportation applications that employ a mobile sensing platform or consist of multiple stationary sensors. In this paper a novel algorithm is presented for multiple-view registration under a loop closure constraint. Different from most existing methods, which use general optimization techniques, our method studies the mechanism of adjusting the poses of views in a loop and provides a highly efficient and accurate solution. We prove that translation vectors can be decoupled if the same point set is used in each view to associate the previous and subsequent views, leading to our solution for such decouplable cases. If this condition does not hold, an exact solution of translation vectors is provided when rotation parameters are given, which results in our iterative solution for general cases by updating rotation and translation alternately. In our method, the effect of the accumulated pose error in a loop can be distributed to all views efficiently through loop factors, and only a few iterations are needed. Most important of all, in each iteration our method has linear computational complexity with respect to the number of views, which is much superior to that of state-of-the-art methods. A series of experiments was conducted, involving simulation of thousands of views and real vehicle-borne sensing data that include 65 371 point pairs in 352 views. Experimental results show that our proposed method is not only stable and highly efficient but also provides competitive accuracy relative to existing methods. ? 2000-2011 IEEE.Accession Number: 20145000314416 -
Record 131 of
Title:Development of the large area MCP-PMT
Author(s):Liu, Shulin(1); Wang, Yifang(1); Zhao, Tianchi(1); Liu, Hulin(2); Si, Shuguang(3); Tian, Jinshou(2); Qian, Sen(1); Sun, Jian-Ning(3); Cai, Xiao(1); Li, Dong(2); Chen, Lin(2); Yan, Baojun(1); Yang, Yuzhen(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9284 Issue: DOI: 10.1117/12.2069902 Published: 2014Abstract:To adapt the specific demands of photomultiplier tubes (PMTs) in the Jiangmen Underground Neutrino Observatory, we design and manufacture a new type of micro-channel plate PMT (MCP-PMT) with the following performance indicators: the PMTs' glass shell adopts the formula of GG-17 which have no K2O, and very low background (the contents of 232Th, 238U and 40K in the raw materials are less than 40 ppb, 20 ppb and10 ppb, respectively). Its main body is sphere with 500 mm external diameter, 4 mm wall thickness and the tails that using a gradual transition of kinds of low radiation background glasses, then sealing with the Kovar. The photocathode material with lowest dark noise is bi-alkali photocathode which spectral region matches the liquid scintillator emission spectral (400～440 nm). The front and back hemisphere is transmission and reflective photocathode separately. Two sets of double-stack micro-channel plates replacing the dynode chain are used to detect the photoelectrons from both sites. The focusing system makes the photoelectrons hit into the inside of MCPs to the uttermost. The anode and lead make sure charge signal is no distortion. No matter made by transfer equipment or not, the peak value of quantum efficiency of the PMT should reach 30%, and the peak-to-valley ratio of single photoelectron spectrum has surpassed 2.5:1. In a word, the MCP-PMT's reliability and other characteristics meet the need of Jiangmen Underground Neutrino Observatory.Accession Number: 20150800546038 -
Record 132 of
Title:Research on ICCD for space observation of cosmic ray and dark matter
Author(s):Hu, Bingliang(1); Gao, Xiaohui(1); Wang, Le(2); Pi, Haifeng(1); Wei, Cuiyu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9144 Issue: DOI: 10.1117/12.2055690 Published: 2014Abstract:The low light level imaging and ultrafast detection system is a high performance ICCD composed of imaging intensifier and high-frame-rate CCD, the important readout system of the semi-digital 3D-imaging calorimeter for space observation of cosmic ray and dark matter that has the function of intensifying, delaying, imaging and memorizing, making rapid response to the ultrafast low light signals that is transmitted by tens of thousands of wavelength shifting fibers, generated by the semi-digital 3D-imaging calorimeter when cosmic ray is passing through. Using the images of ICCD and the semi-digital information reconstruction method, the particle type, energy and direction of cosmic ray can be obtained. By solving some key technologies such as coupling techniques of optical parts, low noise and high speed imaging of high-frame-rate and large-area CCD, the high speed gating system of imager intensifier, the prototype of high performance ICCD is developed. The prototype of ICCD can meet the requirements: up to 400 frames per second, detection ability for low light about 10 photons, linear dynamic range more than 300.Performances verification of the prototype is carried out by using a single photon test system. In this paper we will describe the requirement of ICCD for the ground cosmic detection system which is used to verify the theory of Herd (High Energy Cosmic-Radiation Detection), the key techniques used to achieve perfect performances, and test method and result of the ICCD.Accession Number: 20150700523549