2013
2013
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Record 13 of
Title:Improvement of chirped pulse contrast using electro-optic birefringence scanning filter method
Author(s):Zeng, Shuguang(1,2); Wang, Xianglin(3); Zhang, Bin(2); Wang, Yishan(3); Sun, Nianchun(2); Wang, Fei(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 1 DOI: 10.3788/HPLPB20132501.0047 Published: January 2013Abstract:A method using scanning filter to improve the contrast of chirped pulse is proposed, and the principle of this method is analyzed. The scanning filter is compared with the existing pulse-picking technique and nonlinear filtering technique. The scanning filter is a temporal gate that is independent on the intensity of the pulses, but on the instantaneous wavelengths of light. Taking the electro-optic birefringence scanning filter as an example, the application of scanning filter methods is illustrated. Based on numerical simulation and experimental research, it is found that the electro-optic birefringence scanning filter can eliminate a prepulse which is several hundred picoseconds before the main pulse, and the main pulse can maintain a high transmissivity.Accession Number: 20130315915096 -
Record 14 of
Title:Design of the airborne prism dispersive imaging spectrometer system based on Offner relay configuration
Author(s):Fang, Yu(1,2); Xiangli, Bin(3); Yuan, Yan(4); Lü, Qun-Bo(3); Zhou, Jin-Song(3)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 33 Issue: 3 DOI: 10.3964/j.issn.1000-0593(2013)03-0838-06 Published: March 2013Abstract:Considering the development of the need for small volume and light weight of spectral imaging systems on airborne platform, the characters of several main imaging spectrometers was analyzed and the present paper focuses on introducing imaging spectrometers featuring a grating or a prism disperser. A compact hyperspectral imaging system based on Offner relay configuration is reported. Combining the characters of the concentric Offner relay, and knowing the system design parameters, two novel kinds of spherical spectrometer systems using dispersive elements in divergent and convergent beam were designed. Moreover, the system MTF, spot diagram and the curves of smile and keystone were analyzed. The results show that these two kinds of Offner spectrometer achieve the purpose of a compact form of remote sensing system with excellent imaging quality close to diffraction limit. At the same time, decreasing the smile and keystone to a small (0.1) fraction of a pixel assures uniformity of acquiring spectral data.Accession Number: 20131116114705 -
Record 15 of
Title:Saliency cut in stereo images
Author(s):Peng, Jianteng(1); Shen, Jianbing(1); Jia, Yunde(1); Li, Xuelong(2)Source: Proceedings of the IEEE International Conference on Computer Vision Volume: Issue: DOI: 10.1109/ICCVW.2013.10 Published: 2013Abstract:In this paper, we propose a novel saliency-aware stereo images segmentation approach using the high-order energy items, which utilizes the disparity map and statistical information of stereo images to enrich the high-order potentials. To the best of our knowledge, our approach is first one to formulate the automatic stereo cut as the high-order energy optimization problems, which simultaneously segments the foreground objects in left and right images using the proposed high-order energy function. The relationships of stereo correspondence by disparity maps are further employed to enhance the connections between the left and right images. Experimental results demonstrate that the proposed approach can effectively improve the saliency-aware segmentation performance of stereo images. ? 2013 IEEE.Accession Number: 20141517561649 -
Record 16 of
Title:Theoretical and experimental study of two-phase-stepping approach for hard X-ray differential phase contrast imaging
Author(s):Du, Yang(1,2); Lei, Yao-Hu(1); Liu, Xin(1); Guo, Jin-Chuan(1); Niu, Han-Ben(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 62 Issue: 6 DOI: 10.7498/aps.62.068702 Published: March 20, 2013Abstract:To satisfy the need of low-dose and high-speed in practical application of hard X-ray differential phase contrast imaging, according to the theoretical analysis and the optimal design of parameters for the experimental system, we propose a two-stepping phase shift algorithm to retrieve the object phase information. The method can effectively reduce the radiation dose and substantially improve the speed of retrieving phase information, which lays the foundation for the X-ray phase contrast imaging in medical and industrial applications. ? 2013 Chinese Physical Society.Accession Number: 20132016329333 -
Record 17 of
Title:Effect of the fringe visibility on spectrum SNR of Fourier transform imaging spectrometer
Author(s):Wang, Shuang(1,2); Xiangli, Bin(3); Jing, Juanjuan(1); Pi, Haifeng(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8910 Issue: DOI: 10.1117/12.2032912 Published: 2013Abstract:The principle of Fourier transform spectrometer is based on the relationship of Fourier-Transform between interferogram and spectrum. The spectral information of Fourier transform imaging spectrometer (FTIS) reconstructed from raw interferogram by data processing. So there are two kinds of signal-to-noise ratio (SNR) to evaluate instrument performance, one regarding interferogram and the other regarding reconstructed spectrum. Because the raw interferogram is intuitive, the interferogram SNR is studied usually. On the contrary, the spectrum SNR is studied less because of the complexity of the data processing from interferogram to spectrum. The research about the effect of the interference fringe visibility on the spectrum SNR is especially few. This paper present a research work on the relations between the interference fringe visibility and the spectrum SNR. Firstly, the reduction of fringe visibility caused by imaging lens defocus was analyzed. Secondly, the changes of the average spectrum signal and noise caused by the reduction of fringe visibility were calculated. For average spectrum signal, the math deductions are done base on Fourier transform theory. The average noise with different input signal optic-electrons number are simulated. the results show that the average spectrum signal is directly proportional to the fringe visibility, and the effect of fringe visibility on the noise related to signal can be ignorable. Finally, In order to demonstrate above results, the imaging experiment was done with white-light source, using LASIS (Large aperture static imaging spectrometer) based on Sagnac Interferometer. The average spectrum SNRs under different fringe visibility are calculated and analyzed. The experimental results show that: the average spectrum SNRs increase from 42.7 to 62.4. along with the fringe visibility increasing from 0.5051 to 0.687. the reconstructed spectrum SNR is directly proportional to the fringe visibility. As a result, the interferogram fringe visibility can be used to estimate the reconstructed spectrum SNR, and evaluate the performance of FTIS before data processing. ? 2013 SPIE.Accession Number: 20141317516374 -
Record 18 of
Title:A method for eliminating zero-order image in digital holograph based on contourlet transform
Author(s):Zhang, Yu Fei(1); Wu, Yi Quan(2)Source: Advanced Materials Research Volume: 760-762 Issue: DOI: 10.4028/www.scientific.net/AMR.760-762.80 Published: 2013Abstract:In the reconstruction process of digital holograph, zero-order image has a bad impact on the quality of real image. In this paper, a new way to eliminate zero-order image in digital holography is proposed. Firstly, digital holography image is decomposed by contourlet transform, then remove the low frequency. The new digital holography image is obtained by inverse contourlet transform. Experiments show that, compared with spatial filtering, frequency domain filtering, laplacian filtering and eliminate zero-order image method based on wavelet, the new method proposed in this paper can eliminate zero-order image better, what's more, the real image is also strengthened in some way. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20134416937715 -
Record 19 of
Title:Controlled focus shaping with generalized cylindrical vector beam
Author(s):Chen, Lingling(1,2); Wang, Jiming(1,3); He, Chongjun(1); Liu, Youwen(1); Yun, Maojin(4); Kong, Weijin(4)Source: Journal of Modern Optics Volume: 60 Issue: 5 DOI: 10.1080/09500340.2013.779392 Published: March 1, 2013Abstract:An optical system is proposed for the controlled focus shaping of generalized cylindrical vector beams by a high-numerical-aperture lens. A segmented electro-optical filter with four concentric belts is introduced and works with a double-λ/2-plate. By controlling the rotational angle of the plate and the voltage applied to the filter with proper azimuth angle, a three-dimensional engineered focusing field, such as an electrically controlled axial-shifted focus, extended depth of focus, and a diffraction-limited optical tube, can be achieved. The main advantage of this focusing system is that the focused field can be adjusted and formed by the applied voltage and the rotational angle of the half-wave plates. It can provide a new focus shaping technique with free adjustability and flexibility. ? 2013 Taylor and Francis Group, LLC.Accession Number: 20131716226958 -
Record 20 of
Title:Building holistic descriptors for scene recognition: A multi-objective genetic programming approach
Author(s):Liu, Li(1); Shao, Ling(1); Li, Xuelong(2)Source: MM 2013 - Proceedings of the 2013 ACM Multimedia Conference Volume: Issue: DOI: 10.1145/2502081.2502095 Published: 2013Abstract:Real-world scene recognition has been one of the most challenging research topics in computer vision, due to the tremendous intra- class variability and the wide range of scene categories. In this paper, we successfully apply an evolutionary methodology to automatically synthesize domain-adaptive holistic descriptors for the task of scene recognition, instead of using hand-tuned descriptors. We address this as an optimization problem by using multi-objective genetic programming (MOGP). Specifically, a set of primitive operators and filters are first randomly assembled in the MOGP frame- work as tree-based combinations, which are then evaluated by two objective fitness criteria i.e., the classification error and the tree complexity. Finally, the best-so-far solution selected by MOGP is regarded as the (near-)optimal feature descriptor for scene recognition. We have evaluated our approach on three realistic scene datasets: MIT urban and nature, SUN and UIUC Sport. Experimental results consistently show that our MOGP-generated de- scriptors achieve significantly higher recognition accuracies com- pared with state-of-the-art hand-crafted and machine-learned features. Copyright ? 2013 ACM.Accession Number: 20134716995631 -
Record 21 of
Title:Dayside aurora classification via BIFs-based sparse representation using manifold learning
Author(s):Han, Bing(1,2); Zhao, Xiaojing(1,2); Tao, Dacheng(3); Li, Xuelong(4); Hu, Zejun(5); Hu, Hongqiao(5)Source: International Journal of Computer Mathematics Volume: Issue: DOI: 10.1080/00207160.2013.831084 Published: 2013Abstract:Aurora is the typical ionosphere track generated by the interaction of solar wind and magnetosphere, whose modality and variation are significant to the study of space weather activity. A new aurora classification algorithm based on biologically inspired features (BIFs) and discriminative locality alignment (DLA) is proposed in this paper. First, an aurora image is represented by the BIFs, which combines the C1 units from the hierarchical model of object recognition in cortex and the gist features from the saliency map; then, the manifold learning method called DLA is used to obtain the effective sparse representation for auroras based on BIFs; finally, classification results using support vector machine and nearest neighbour with three sets of features: the C1 unit features, the gist features and the BIFs illustrate the effectiveness and robustness of our method on the real aurora image database from Chinese Arctic Yellow River Station. ? 2013 ? 2013 Taylor & Francis.Accession Number: IP52877255 -
Record 22 of
Title:Ranking graph embedding for learning to rerank
Author(s):Pang, Yanwei(1); Ji, Zhong(1); Jing, Peiguang(1); Li, Xuelong(2)Source: IEEE Transactions on Neural Networks and Learning Systems Volume: 24 Issue: 8 DOI: 10.1109/TNNLS.2013.2253798 Published: 2013Abstract:Dimensionality reduction is a key step to improving the generalization ability of reranking in image search. However, existing dimensionality reduction methods are typically designed for classification, clustering, and visualization, rather than for the task of learning to rank. Without using of ranking information such as relevance degree labels, direct utilization of conventional dimensionality reduction methods in ranking tasks generally cannot achieve the best performance. In this paper, we show that introducing ranking information into dimensionality reduction significantly increases the performance of image search reranking. The proposed method transforms graph embedding, a general framework of dimensionality reduction, into ranking graph embedding (RANGE) by modeling the global structure and the local relationships in and between different relevance degree sets, respectively. The proposed method also defines three types of edge weight assignment between two nodes: binary, reconstruction, and global. In addition, a novel principal components analysis based similarity calculation method is presented in the stage of global graph construction. Extensive experimental results on the MSRA-MM database demonstrate the effectiveness and superiority of the proposed RANGE method and the image search reranking framework. ? 2012 IEEE.Accession Number: 20133216579235 -
Record 23 of
Title:3 W high-power laser passively mode-locked by graphene oxide saturable absorber
Author(s):Feng, Chao(1); Wang, Yonggang(2,3); Liu, Jie(1); Tsang, Yuen H.(2); Song, Yanrong(4); Yu, Zhenhua(4)Source: Optics Communications Volume: 298-299 Issue: DOI: 10.1016/j.optcom.2013.02.003 Published: July 1, 2013Abstract:A novel reflective graphene oxide based saturable absorber is fabricated and used to passively mode locked the Nd:YVO4 ultrafast laser system. The maximum average output power measured is 3.06 W and the optical to optical conversion efficiency is about 25%. The measured pulse duration and repetition rate are 8.8 ps and 84 MHz. The maximum peak power and the single pulse energy of the mode-locking laser are up to 4.1 kW and 36 nJ, respectively. To the best of our knowledge, it is the highest average output power for the lasers mode locked with graphene based absorbers. ? 2013 Elsevier B.V. All rights reserved.Accession Number: 20131616211228 -
Record 24 of
Title:The improved design of encoding mask and the correcting method for recovered spectral images in Hadamard transform spectral imager based on DMD
Author(s):Xu, Jun(1); Xie, Cheng-Wang(2); Liu, Hai-Wen(1); Liu, Qiang(3); Li, Bin-Cheng(4)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 33 Issue: 5 DOI: 10.3964/j.issn.1000-0593(2013)05-1419-05 Published: May 2013Abstract:A novel type of DMD-based Hadamard transform spectral imager is introduced. Taking the 7-order S-matrix as an example for discussion, the present paper develops an improved design of Hadamard encoding mask, which makes the dispersed spectrum of all pixels to be encoded by seven elements strictly. A correcting method for the recovered spectral images is proposed, and eventually 6 high-quality spectral images are obtained when Hadamard transform spectral imager operates based on 7-order S-matrix. Similarly, if the spectral imager operates based on n-order S-matrix, n-1 spectral images can be obtained. The experimental results show that the improved design and the correction method are feasible and effective.Accession Number: 20132016340402