2011
2011
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Record 409 of
Title:Calculations on optical path difference of a high resolution reflecting scanning Fourier transform spectrometry
Author(s):Wei, Ruyi(1,2,3); Zhang, Xuemin(2,3); Zhou, Jinsong(4); Zhou, Sizhong(2); Gao, Xiaohui(1,2,3); Wei, Junxia(1,2,3); Wang, Le(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 7 DOI: 10.3788/AOS201131.0730001 Published: July 2011Abstract:A new high resolution reflecting scanning Fourier transform spectrometry produces nonlinear optical path difference (OPD) by rotating two tilted plane mirrors. OPD plays an important role in evaluating the performance and parameters and designing the spectrometry. Based on analyzing the principle of this reflecting scanning Fourier transform spectrometry, we adopt two methods to study OPD. One method is conventional tracing rays method by tracing rays following the Malus law, the other is novel point-image method by using mirror imaging principle and computer simulation to calculate OPD. The general expression of OPD with time change is deduced by the tracing rays method, and factors associated with the change of OPD are pointed out. Factors and their weights on the maximum OPD are also discussed. The calculation results demonstrate that OPD is closely related to the spatial distance between the primary rotating mirror (PRM) and secondary rotating mirror (SRM), the tilted angle between rotating mirrors' plane and the plane perpendicular to rotational axis, and the incident angle between incident beam split from beam splitter and the rotational axis. Also, it is proved that the tracing rays method and point-image method are both feasible and efficient; and the simulation curves of them agree with each other.Accession Number: 20113114199178 -
Record 410 of
Title:Designs of multipass optical configurations based on the use of a cube corner retroreflector in the interferometer
Author(s):Wei, Ruyi(1,2,3); Zhang, Xuemin(2,3); Zhou, Jinsong(4); Zhou, Sizhong(2)Source: Applied Optics Volume: 50 Issue: 12 DOI: 10.1364/AO.50.001673 Published: April 20, 2011Abstract:We describe designs of the multipass optical configurations of an interferometer with high spectral resolution with respect to 6, 12, and 24 times more optical passes than the conventional Michelson interferometer. In each design, a movable cube corner retroreflector is combined with a folding reflector group (FRG) as the interferometer's moving combination to implement the multipass optical configuration with the characteristic of surface division. Analyses reveal that when there are 12 or more optical passes, the net effect of the ray's angular deviation of the entire moving combination amounts to only the alignment error of one of the reflectors in the FRG, demonstrating the self-aligning property of the interferometer. ? 2011 Optical Society of America.Accession Number: 20112414066616 -
Record 411 of
Title:Optical focusing by planar lenses based on nano-scale metallic slits in visible regime
Author(s):Feng, Di(1,2); Zhang, Chunxi(2)Source: Physics Procedia Volume: 22 Issue: DOI: 10.1016/j.phpro.2011.11.067 Published: 2011Abstract:A kind of planar metallic lenses is proposed to realize optical focusing in the visible wavelength through a metallic film with nano-scale slit arrays, which have the same depth but tuning widths. Due to the subwavelength and aperiodic nature of planar metallic lenses, we present the rigorous electromagnetic analysis by using two dimensional finite difference time domain method. The electromagnetic wave transports through the tuning slits in the form of surface plasmon polaritons, and gets the required phase retardations to focusing at the focal plane. We analyze the focusing characteristics of planar dielectric lens and metallic lens with tuning widths that are obtained by generalizing the relevant phase delay, for different incidence polarization waves (TM polarized case and TE polarized case). The computational calculation results show that, extraordinary optical transmission of surface plasmon polaritions through non uniform nano-scale metallic slits is observed, and it has contributions to the optical focusing, but cannot increase the focal energy compared with dielectric planar lens with the same profile, and the metallic lenses are more sensitive to the polarization of incidence wave than that of dielectric lenses. The influence of metallic lenses' thickness on the focal characteristics has been analyzed also. ? 2011 Published by Elsevier B.V.Accession Number: 20120814783334 -
Record 412 of
Title:Shadow detection in remotely sensed images based on self-adaptive feature selection
Author(s):Liu, Jiahang(1,2); Fang, Tao(1); Li, Deren(3)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 49 Issue: 12 PART 2 DOI: 10.1109/TGRS.2011.2158221 Published: December 2011Abstract:Shadows in remotely sensed images create difficulties in many applications; thus, they should be effectively detected prior to further processing. This paper presents a novel semiautomatic shadow detection method that meets the requirements of both high accuracy and wide practicability in remote sensing applications. The proposed method uses only the properties derived from the shadow samples to dynamically generate a feature space and calculate decision parameters; then, it employs a series of transformations to separate shadow and nonshadow regions. The proposed method can detect shadows from both color and gray images. If the chromatic properties of color images do not agree with the defined rules through the shadow samples, then the shadow detection process will automatically reduce to the process for gray images. As the shadow samples are manually selected from the input image by the user, the derived parameters conform well to the characteristics of the input image. Experiments and comparisons indicate that the proposed self-adaptive feature selection algorithm is accurate, effective, and widely applicable to shadow detection in practical applications. ? 2011 IEEE.Accession Number: 20114814567925 -
Record 413 of
Title:The multi-spectra classification algorithm based on K-means clustering and spectral angle cosine
Author(s):Wei, Jun-Xia(1,3); Xiangli, Bin(2); Gao, Xiao-Hui(1,3); Duan, Xiao-Feng(1)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 31 Issue: 5 DOI: 10.3964/j.issn.1000-0593(2011)05-1357-04 Published: May 2011Abstract:The classification and de-aliasing methods with respect to multi-spectra and hyper-spectra have been widely studied in recent years. And both K-mean clustering algorithm and spectral similarity algorithm are familiar classification methods. The present paper improved the K-mean clustering algorithm by using spectral similarity match algorithm to perform a new spectral classification algorithm. Two spectra with the farthest distance first were chosen as reference spectra. The Euclidean distance method or spectral angle cosine method then were used to classify data cube on the basis of the two reference spectra, and delete the spectra which belongs to the two reference spectra. The rest data cube was used to perform new classification according to a third spectrum, which is the farthest distance or the biggest angle one corresponding to the two reference spectra. Multi-spectral data cube was applied in the experimental test. The results of K-mean clustering classification by ENVI, compared with simulation results of the improved K-mean algorithm and the spectral angle cosine method, demonstrated that the latter two classify two air bubbles explicitly and effectively, and the improved K-mean algorithm classifies backgrounds better, especially the Euclidean distance method can classify the backgrounds integrally.Accession Number: 20112114007172 -
Record 414 of
Title:Mammographic mass segmentation: Embedding multiple features in vector-valued level set in ambiguous regions
Author(s):Wang, Ying(1); Tao, Dacheng(2,4); Gao, Xinbo(1); Li, Xuelong(3); Wang, Bin(1)Source: Pattern Recognition Volume: 44 Issue: 9 DOI: 10.1016/j.patcog.2010.08.002 Published: September 2011Abstract:Mammographic mass segmentation plays an important role in computer-aided diagnosis systems. It is very challenging because masses are always of low contrast with ambiguous margins, connected with the normal tissues, and of various scales and complex shapes. To effectively detect true boundaries of mass regions, we propose a feature embedded vector-valued contour-based level set method with relaxed shape constraint. In particular, we initially use the contour-based level set method to obtain the initial boundaries on the smoothed mammogram as the shape constraint. To prevent the contour leaking and meanwhile preserve the radiative characteristics of specific malignant masses, afterward, we relax the obtained shape constraint by analyzing possible valid regions around the initial boundaries. The relaxed shape constraint is then used to design a novel stopping function for subsequent vector-valued level set method. Since texture maps, gradient maps, and the original intensity map can reflect different characteristics of the mammogram, we integrate them together to obtain more accurate segmentation by incorporating the new stopping function into the newly proposed feature embedded vector-valued contour-based level set method. The experimental results suggest that the proposed feature embedded vector-valued contour-based level set method with relaxed shape constraint can effectively find ambiguous margins of the mass regions. Comparing against existing active contours methods, the new scheme is more effective and robust in detecting complex masses. ? 2010 Elsevier Ltd. All rights reserved.Accession Number: 20112214012679 -
Record 415 of
Title:Hyperspectral image compression technology research based on EZW
Author(s):Wei, Jun-Xia(1,2,4); Xiangli, Bin(3); Duan, Xiao-Feng(1,2); Xu, Zhao-Hui(5); Xue, Li-Jun(1,2)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 31 Issue: 8 DOI: 10.3964/j.issn.1000-0593(2011)08-2283-04 Published: August 2011Abstract:Along with the development of hyperspectral remote sensing technology, hyperspectral imaging technology has been applied in the aspect of aviation and spaceflight, which is different from multispectral imaging, and with the band width of nanoscale spectral imaging the target continuously, the image resolution is very high. However, with the increasing number of band, spectral data quantity will be more and more, and these data storage and transmission is the problem that the authors must face. Along with the development of wavelet compression technology, in field of image compression, many people adopted and improved EZW, the present paper used the method in hyperspectral spatial dimension compression, but does not involved the spectrum dimension compression. From hyperspectral image compression reconstruction results, whether from the peak signal-to-noise ratio (PSNR) and spectral curve or from the subjective comparison of source and reconstruction image, the effect is well. If the first compression of image from spectrum dimension is made, then compression on space dimension, the authors believe the effect will be better.Accession Number: 20113214216483 -
Record 416 of
Title:Single-image super-resolution via sparse coding regression
Author(s):Tang, Yi(1); Yuan, Yuan(1); Yan, Pingkun(1); Li, Xuelong(1)Source: Proceedings - 6th International Conference on Image and Graphics, ICIG 2011 Volume: Issue: DOI: 10.1109/ICIG.2011.63 Published: 2011Abstract:In this paper, it has been shown that the sparse coding algorithm for single-image super-resolution is equivalent to a linear regression algorithm in the sparse coding space. Following the idea, the sparse coding algorithm are generalized by a novel L2-Boosting-based single-resolution super-resolution algorithm which focuses on the relationship between sparse codings corresponding to the low- and high-resolution image patches. The experimental results demonstrate the effectiveness of the proposed algorithm by comparing with other state-of-the- art algorithms. ? 2011 IEEE.Accession Number: 20113914361975 -
Record 417 of
Title:Continuous wave operation of Tm2O3-doped germanate glass laser around 2 μm
Author(s):Zou, Yuwan(1); Wang, Qing(1); Zhang, Yongdong(1); Li, Dehua(1); Wei, Zhiyi(1); Ling, Weijun(2); Fan, Jintai(3); Zhang, Long(3)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 38 Issue: 4 DOI: 10.3788/CJL201138.0402004 Published: April 2011Abstract:A continuous-wave (CW) Tm2O3-doped FGe glass laser is demonstrated. An uncoated one percent of mole fraction Tm2O3-doped GeO2-Ga2O3 -BaF2-MO/F2 (FGe) glass is employed as the laser medium. Pumped with a Ti:sapphire laser at 790 nm, CW laser is realized using two kinds of output couplers (OC). Under the 3% OC, output power of 83 mW is obtained, corresponding to a slope efficiency of 13.7%, and the optical conversion efficiency is 8.8%. The measured central wavelength is 1968 nm.Accession Number: 20112114002513 -
Record 418 of
Title:Study of the error of the reference lens in absolute spherical testing and the thermal deformation model establishment
Author(s):Chen, Xu(1,2); Yuan, Wenquan(1); Feng, Yutao(3); Wang, Ping(1); Liu, Weiqi(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 2 DOI: 10.3788/AOS201131.0212002 Published: February 2011Abstract:Absolute measurement is an important method to improve the accuracy of the Fizeau interferometer. To achieve the high accuracy of the reference wave front in absolute spherical testing, the influence of environmental factors including temperature, gravity and clamping force was studied. The Gram-Schmidt fitting was used to fit the deformation of the reference surface in representation of the Zernike coefficients. The contribution of the thermal deformation by temperature change and the change in Zernike coefficients caused just by temperature change were compared. The model of the thermal deformation was created and the corresponding aberration mode of the reference surface was analyzed which make the separation of the deformation caused by temperature possible so that the test accuracy can be enhanced. The result indicates that the deformation of fused silica is smaller than that of K9 and zerodur on the whole while the deformation of zerodur is smaller than that of K9 and fused silica in just temperature change. When the temperature takes one degree change, the root mean square of the zerodur surface reaches 0.37 nm.Accession Number: 20111413890962 -
Record 419 of
Title:General coupled-mode analysis for gain-guided, index-antiguided fibers, and index-guided fibers
Author(s):Zhou, Enyu(1); Yan, Kunlun(2); Zhao, Baoyin(2); Wang, Yishan(2); Wei, Wei(2,3); Peng, Bo(2,3)Source: Optics Communications Volume: 284 Issue: 4 DOI: 10.1016/j.optcom.2010.10.067 Published: February 15, 2011Abstract:Coupling properties of two gain-guided, index-antiguided (GG + IAG) fibers, or GG + IAG fibers and index-guided (IG) fibers, were investigated by the further general coupled-mode theory. The theory can explain any situation of two fiber coupling. The interesting results were obtained by the numerical computation method. For two GG + IAG fiber coupling, total power was decreased as rising real-valued refractive-index difference (real part of refractive-index difference between core and cladding, RVRID), while the power of one GG + IAG fiber was damped oscillations with increased core separation. In the GG + IAG fiber and IG fiber coupler, the variation of the RVRID could change coupling characteristics. These results are different from two IG fibers coupling, and the general coupled-mode theory may provide meaningful references for new concepts of directional coupler and pumping technology of GG + IAG fiber. ? 2010 Elsevier B.V. All rights reserved.Accession Number: 20104913465596 -
Record 420 of
Title:Design of large dimension and rear projecting lens in laser display system
Author(s):Chen, Xu(1,2); Feng, Yu-Tao(3); Liu, Wei-Qi(1); Wei, Zhong-Lun(1); Kang, Yu-Si(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 19 Issue: 5 DOI: 10.3788/OPE.20111905.0945 Published: May 2011Abstract:After comparing different structures of wide-angle projecting lenses, a wide-angle lens for 162.6 cm(64 in) rear projection laser display is designed. The focal length of the system is 7.38 mm, the wavelength used in the design is F, d, C and the full field of view reaches 100°. The technical indii of the projection lens are summarized as follows: DMD (Digital Micromirror Delice) is used in the light digital processing, 90% MTF is greater than 0.6 at the Nyquist frequency; the barrel distortion of the system is smaller than 1.4%, and 90% of the energy in the point target is focused in a pixel dimension. Furthermore, a right angle prism is used to fold the optical path to decrease the length of the lens, so that the whole optical length of the system is 259 mm after outspreading the right angle prism. The vignetting factor of the wide angle is negative, which enhances the image illumination after projection. Moreover, an aspheric surface with the small size, zero conic constant and the maximum eight order coefficient is used to promise the feasibility of the mounting. Analytical results show that the design can decrease the production costs of the projecting system and promote the technological industrialization.Accession Number: 20112614103086