2014
2014
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Record 193 of
Title:Passively Q-switched Nd:YAG laser with graphene oxide in heavy water
Author(s):Wen, Qiao(1,2); Zhang, Xiaojun(1,2); Wang, Yonggang(1,3); Wang, Yishan(3); Niu, Hanben(1)Source: IEEE Photonics Journal Volume: 6 Issue: 2 DOI: 10.1109/JPHOT.2014.2309631 Published: April 2014Abstract:Liquid saturable absorbers have some advantages in some aspects over solid saturable absorbers. In this paper, graphene oxide in heavy water (deuteroxide, D2O) dispersion was fabricated and used as absorber in Q-switched Nd:YAG laser for the first time, to the best of our knowledge. The shortest pulse width of the Q-switched laser is 523 ns, corresponding to a repetition rate of 92.9 kHz. The maximum peak power of Q-switched pulse is 6.6 W. Such a liquid absorber has the virtues of good optical transparency, high heat dissipation, and no contact damage. ? 2014 IEEE.Accession Number: 20141417546800 -
Record 194 of
Title:Low-timing-jitter mode-locked fiber laser based on graphene oxide PVA thin film as saturable absorber
Author(s):Wu, Kan(1); Li, Xiaohui(2); Wang, Yonggang(3); Wang, Qijie(2); Shum, Perry Ping(2); Chen, Jianping(1)Source: Asia Communications and Photonics Conference, ACP Volume: 2014-November Issue: DOI: Published: November 2014Abstract:We demonstrate a mode-locked fiber laser based on graphene oxide saturable absorber at 1550nm. The laser has a timing jitter of 53fs (100Hz to 100kHz). The contribution from the slow saturable absorber is also investigated. ? OSA 2014Accession Number: 20203909223152 -
Record 195 of
Title:Optical system design of multi-spectral camera for space debris
Author(s):Wang, Hu(1,2); Luo, Jianjun(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 4 DOI: Published: April 2014Abstract:In order to detect the Space debris, a multi-spectral camera for Space debris was proposed. The multi-spectral camera was consisted of visible camera, long-wave infrared (LWIR) camera and mid- wave infrared (MWIR) camera. Three cameras used the primary mirror and secondary mirror together, including correction lens in every camera in order to balance aberration. The focal length was 1000 mm and field of view was 1.2° for visible camera, and the focal length was 250 mm and field of view was 2.75° for LWIR camera, and the focal length was 500 mm and field of view was 1.38° for MWIR camera. 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 three cameras in condition of 20±5°C was analyzed, which showed a good result for user's requirement.Accession Number: 20142217774875 -
Record 196 of
Title:Design of high power light absorber
Author(s):Li, Hongguang(1); Da, Zhengshang(1); Sun, Ce(1); Dong, Xiaona(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 7 DOI: Published: July 25, 2014Abstract:In order to realize the 109 times absorption for residual laser after 4% sampling, a kind of design method of light absorber was given. From light entrance to light exit the absorber, total angle relations were derived, including the angle of entrance light intersection with the absorber, turnover angle from entrance to exit, the angle of exit light intersection with the absorber, and turnover angle of the light departure from the absorber. The calculated angles were taken into polarization formula, and the sampling efficiency from every intersection was gotten, and so the total process attenuation was obtained from light entrance to light exit the absorber. According to the above formulas, a kind of absorber was designed, and it was analyzed in optical software. The results show that the absorption can reach to 1011, which satisfies the absorption requirements and is identical with theory calculation; This kind of absorber has been used in the laser system well, near field image with modulation MAccession Number: 20143600062414 -
Record 197 of
Title:Low-timing-jitter mode-locked fiber laser based on graphene oxide PVA thin film as saturable absorber
Author(s):Wu, Kan(1); Li, Xiaohui(2); Wang, Yonggang(3); Wang, Qijie(2); Shum, Perry Ping(2); Chen, Jianping(1)Source: Asia Communications and Photonics Conference, ACPC 2014 Volume: Issue: DOI: 10.1364/acpc.2014.af1c.3 Published: November 14, 2014Abstract:We demonstrate a mode-locked fiber laser based on graphene oxide saturable absorber at 1550nm. The laser has a timing jitter of 53fs (100Hz to 100kHz). The contribution from the slow saturable absorber is also investigated. ? OSA 2014.Accession Number: 20151900831592 -
Record 198 of
Title:Three operation regimes with an L-band ultrafast fiber laser passively mode-locked by graphene oxide saturable absorber
Author(s):Zhao, Junqing(1); Wang, Yonggang(2); Ruan, Shuangchen(1); Yan, Peiguang(1); Zhang, Han(3); Tsang, Yuen H.(4); Yang, Jinhui(1); Huang, Guoxi(1)Source: Journal of the Optical Society of America B: Optical Physics Volume: 31 Issue: 4 DOI: 10.1364/JOSAB.31.000716 Published: April 1, 2014Abstract:We present three operation regimes with an L-band erbium-doped fiber laser passively mode-locked by a graphene oxide saturable absorber (GOSA) that is fabricated by using a wet chemical method. One is a stable state of single soliton emission with pulse duration of 426 fs, which is the shortest pulse duration ever achieved with an L-band design by employing GOSA as the mode-locker. The other two operation regimes include bound-state soliton and dual-wavelength nanosecond pulse generation, which are demonstrated for the first time by using the GOSA mode-locker. Our results further indicate the practical potential of GOSA in ultrafast fiber lasers for achieving various mode-locking regimes. ? 2014 Optical Society of America.Accession Number: 20141617573122 -
Record 199 of
Title:Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity
Author(s):Li, Xuefeng(1); Cao, Guangzhan(2); Liu, Hongjun(2)Source: AIP Advances Volume: 4 Issue: 4 DOI: 10.1063/1.4871406 Published: April 2014Abstract:Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems. ? 2014 Author(s).Accession Number: 20141717603644 -
Record 200 of
Title:Corner detection using gabor filters
Author(s):Zhang, Wei-Chuan(1); Wang, Fu-Ping(2); Zhu, Lei(1); Zhou, Zuo-Feng(3)Source: IET Image Processing Volume: 8 Issue: 11 DOI: 10.1049/iet-ipr.2013.0641 Published: November 14, 2014Abstract:This study proposes a contour-based corner detector using the magnitude responses of the imaginary part of the Gabor filters on contours. Unlike the traditional contour-based methods that detect corners by analysing the shape of the edge contours and searching for local curvature maxima points on planar curves, the proposed corner detector combines the pixels of the edge contours and their corresponding grey-variation information. Firstly, edge contours are extracted from the original image using Canny edge detector. Secondly, the imaginary parts of the Gabor filters are used to smooth the pixels on the edge contours. At each edge pixel, the magnitude responses at each direction are normalised by their values and the sum of the normalised magnitude response at each direction is used to extract corners from edge contours. Thirdly, both the magnitude response threshold and the angle threshold are used to remove the weak or false corners. Finally, the proposed detector is compared with five state-of-the-art detectors on some grey-level images. The results from the experiment reveal that the proposed detector is more competitive with respect to detection accuracy, localisation accuracy, affine transforms and noise-robustness. ? The Institution of Engineering and Technology 2014.Accession Number: 20150200419116 -
Record 201 of
Title:Analysis and research of stereo correspondence algorithms
Author(s):Li, Yan-Yun(1,2); Liu, Zhao-Hui(2); Zhou, Liang(1,2)Source: Applied Mechanics and Materials Volume: 568-570 Issue: DOI: 10.4028/www.scientific.net/AMM.568-570.768 Published: 2014Abstract:Stereo matching has been the focus of computer vision research. Some current researches on stereo matching algorithms were summarized, the stereo matching key techniques were analyzed; View of the current major challenges on binocular stereo matching, elaborated matching algorithm possible solutions and modification approaches; Finally, the field of technology development are prospected. ? (2014) Trans Tech Publications, Switzerland.Accession Number: 20142717908454 -
Record 202 of
Title:A novel compact large relative aperture visible optical system
Author(s):Wang, Hu(1,2); Luo, Jianjun(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 3 DOI: Published: March 2014Abstract:Based on the special chromatic aberration and thermal aberration of diffractive optical element, which are used in optical system of visible camera for space debris, a novel compact and good image quality large relative aperture space debris camera optical system was designed. The novel system solved the problem that the conventional system had small relative aperture and complex structure. The novel system had an effective focal length of 100 mm, a relative aperture of F/1.5, a field of view of 6°. The system met the requirements of visible space debris camera in encirc energy, the dispersion spot diameter, lateral color, distortion, athermalization and so on. This novel system had light weight, compact structure and good image quality by using diffractive optical element, which provided a new idea for designing visible space debris camera optical system.Accession Number: 20142217774733 -
Record 203 of
Title:Interactive segmentation using constrained laplacian optimization
Author(s):Shen, Jianbing(1); Du, Yunfan(1); Li, Xuelong(2)Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 24 Issue: 7 DOI: 10.1109/TCSVT.2014.2302545 Published: July 2014Abstract:We present a novel interactive image segmentation approach with user scribbles using constrained Laplacian graph optimization. A novel energy framework is developed by adding the smoothing item in the cost function of Laplacian graph energy. To the best of our knowledge, our approach is the first to incorporate the normalized cuts and graph cuts algorithms into a unified energy optimization framework. The proposed approach is further accelerated by running the proposed optimization method on a band region when we segment the large images. Our acceleration strategy enables our approach to efficiently segment the large images, which yields about a 20-80 times speedup. The proposed approach is evaluated on both the publicly available data sets and our own data set with large images. The benefits of the proposed unified framework are also demonstrated both qualitatively and quantitatively. The experimental results show that our segmentation method achieves better performance of both boundary recall and error rate than the existing state-of-the-art approaches. ? 1991-2012 IEEE.Accession Number: 20142917959451 -
Record 204 of
Title:Testing of large relative aperture convex aspheric lens with doublets
Author(s):Chen, Qin-Fang(1); Ma, Zhen(1); Zhao, Meng(1); Fang, Hu(1); Wang, Hu(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 3 DOI: 10.3788/gzxb20144303.0322004 Published: March 2014Abstract:It is difficult to fabricate and test convex aspherical surfaces, especially for steep convex aspheical surfaces. Based on the analysis of the conventional null test, a simple test system with cemented doublet for two steep convex ellipsoids was discussed. The wavefront of the both test system was less than 1/30λ RMS (Root Meat Square, λ=632.8 nm). The convex aspheric lens had their successful application in practical optical system. The result showed that the null test for convex aspheric lens discussed in this paper is valid. Compared with the traditional test method, the cemented doublet offsets the spherical aberration generated by the sphere surface of the lens. So the proposed test method decreases the amount of the spherical aberration generated by the aspherical lens, with fewer elements, and reduces the system's alignment difficulty. It was demonstrated to be an effective, high-precision testing method.Accession Number: 20141717623301