2013
2013
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Record 169 of
Title:Formation of nanogratings in a transparent material with tunable ionization property by femtosecond laser irradiation
Author(s):Umran, Fadhil A.(1,2); Liao, Yang(2); Elias, Mazin M.(1); Sugioka, Koji(3); Stoian, Razvan(4); Cheng, Guanghua(5); Cheng, Ya(2)Source: Optics Express Volume: 21 Issue: 13 DOI: 10.1364/OE.21.015259 Published: July 1, 2013Abstract:Irradiation inside some transparent materials such as fused silica can induce nanograting structures at the focal area. Here, we investigate experimentally how the nanograting formation can be influenced by tuning the ionization property of the transparent material, which is achieved by irradiation inside a porous glass immersed in water doped with NaCl at variable concentrations. Our results show that the doping of NaCl not only reduces the threshold fluence of optical breakdown, but also leads to nanograting structures with shorter periods. These effects may be attributed to the enhanced photoionization in water doped with NaCl. ? 2013 Optical Society of America.Accession Number: 20132916502859 -
Record 170 of
Title:Empirical mode decomposition based background removal and de-noising in polarization interference imaging spectrometer
Author(s):Zhang, Chunmin(1,2); Ren, Wenyi(1,2,3); Mu, Tingkui(1,2); Fu, Lili(1,3); Jia, Chenling(1,2)Source: Optics Express Volume: 21 Issue: 3 DOI: 10.1364/OE.21.002592 Published: February 11, 2013Abstract:Based on empirical mode decomposition (EMD), the background removal and de-noising procedures of the data taken by polarization interference imaging interferometer (PIIS) are implemented. Through numerical simulation, it is discovered that the data processing methods are effective. The assumption that the noise mostly exists in the first intrinsic mode function is verified, and the parameters in the EMD thresholding de-noising methods is determined. In comparison, the wavelet and windowed Fourier transform based thresholding de-noising methods are introduced. The de-noised results are evaluated by the SNR, spectral resolution and peak value of the de-noised spectrums. All the methods are used to suppress the effect from the Gaussian and Poisson noise. The de-noising efficiency is higher for the spectrum contaminated by Gaussian noise. The interferogram obtained by the PIIS is processed by the proposed methods. Both the interferogram without background and noise free spectrum are obtained effectively. The adaptive and robust EMD based methods are effective to the background removal and de-noising in PIIS. ? 2013 Optical Society of America.Accession Number: 20130916050893 -
Record 171 of
Title:Improvement of MTF measurement and analysis using knife-edge method
Author(s):Bu, Fan(1,3); Qiu, Yuehong(1); Yan, Xingtao(2,3)Source: Journal of Computational Information Systems Volume: 9 Issue: 3 DOI: Published: February 1, 2013Abstract:Modulation transfer function (MTF) is more authoritative in evaluating the performance of optical imaging system. Therefore, measuring MTF directly from the information of remote sensing image is an important method to monitor on-orbit satellites. This paper chooses knife-method which is applicable for MTF measurement of on-orbit satellites. In the process of calculating MTF, a new-type nonlinear least squares iteration algorithm, instead of simulated annealing algorithm, is selected to approach ESF using the Fermi function. Simulation results show that the new algorithm has greater superiority in the precision and speed. Furthermore, on the basis of implementation of MTF measurement, this paper studies the influence of edge height and angle on MTF, and tests the precision of the method. Copyright ? 2013 Binary Information Press.Accession Number: 20131516191821 -
Record 172 of
Title:Design of the microlens arrays coupling with imaging fiber bundle
Author(s):Yan, Xing-tao(1,2); Yang, Jian-feng(1); Xue, Bin(1); Ma, Xiao-long(1); Li, Fu(1); Zhao, Yi-yi(1,2); Bu, Fan(1,2)Source: Optoelectronics Letters Volume: 9 Issue: 3 DOI: 10.1007/s11801-013-3016-4 Published: May 2013Abstract:To ameliorate the disadvantages of imaging system coupled with imaging fiber bundle, a method by adding square aperture microlens arrays at both entrance and exit ends of the imaging fiber bundle is proposed to increase the system's coupling efficiency. The expressions for solving the parameters of both ends' microlens units are deducted particularly. The microlens arrays used for an infrared imaging fiber bundle with the single fiber diameter of 100 μm and core diameter of 70 μm are designed by this method. The simulation results show that compared with the system without microlens arrays, the fill factor of the imaging fiber bundle coupled microlens arrays system is increased from 44. 4% to more than 90%, and the coupling efficiency is doubled too. So the design method is correct, and the introduction of microlens arrays into imaging fiber bundle coupled system is feasible and superior. ? 2013 Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.Accession Number: 20131916319670 -
Record 173 of
Title:Study of Hadamard transform spectral imager for faint object detection
Author(s):Xin, Sun(1,2); Shi, Da-Lian(1,2,3); Wang, Le(1,2); Li, Li-Bo(1,2,3); Hu, Bing-Liang(1,2); Li, Yun(1,2,3)Source: Proceedings of the International Astronautical Congress, IAC Volume: 4 Issue: DOI: Published: 2013Abstract:The multiplexing advantages of Hadamard Transform Spectrometer (HTS) make this type of instrument a different approach to spatial-target detection other than Fourier Transform spectrometer (HTS). The signal to noise ratio (SNR) merit and no moving parts of HTS opens the door to multiple spatial applications, especially in the field of object detection, in which the target is in low illumination condition. Two kinds of Hadamard transform spectrometer, which uses advanced spatial light modulator (Digital Micro-mirror Device, DMD?) and traditional mechanic mask are introduced respectively. The first type of HTS, which uses DMD? on the second image plane, can implement the function of spectral domain encoding. The other type of HTS sets the mechanical plate at the first image plane as encoding silts. Each instrument implementation and the operating principles are studied, especially in the aspects of mask positioning method. The feasibility of pushbroom HTS with stationary encoding mask is analyzed. Lastly the paper presents partial simulation results of the data reconstruction. ?2013 by the International Astronautical Federation. All rights reserved.Accession Number: 20143117991910 -
Record 174 of
Title:Special issue: Behaviours in video
Author(s):Zhou, Huiyu(1); Yuan, Yuan(2); Du, Eliza Y(3); Yan, Pingkun(4)Source: Neurocomputing Volume: 100 Issue: DOI: 10.1016/j.neucom.2012.04.018 Published: January 16, 2013Abstract:nullAccession Number: 20124615668436 -
Record 175 of
Title:Finite element analysis of the rolling bearing clearance environmental field with ANSYS
Author(s):Zhang, Hui(1,2); Yang, Xiao Xu(1); Zhang, Xin Jie(1,2); Cao, Hong Yuan(3); Li, Da Wei(1)Source: Applied Mechanics and Materials Volume: 310 Issue: DOI: 10.4028/www.scientific.net/AMM.310.249 Published: 2013Abstract:Due to the complex structure of the rolling bearing, a simplified bearing model was founded and then thermal stress simulation was analyzed with ANSYS. The various parts of the displacement changes can be got. Compared the simulation results with the actual results, it can be drawn that the simulation result is basically same with the analytical result. So the simplified model is right. This method is simple, and can be adapted to the general clearance analysis. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20131216134991 -
Record 176 of
Title:A dielectric-barrier discharge enhanced plasma brush array at atmospheric pressure
Author(s):Li, Xuemei(1); Tang, Jie(2); Zhan, Xuefang(1); Yuan, Xin(1); Zhao, Zhongjun(1); Yan, Yanyue(1); Duan, Yixiang(1)Source: Applied Physics Letters Volume: 103 Issue: 3 DOI: 10.1063/1.4816061 Published: July 15, 2013Abstract:This study developed a large volume cold atmospheric plasma brush array, which was enhanced by a dielectric barrier discharge by integrating a pair of DC glow discharge in parallel. A platinum sheet electrode was placed in the middle of the discharge chamber, which effectively reduced the breakdown voltage and working voltage. Emission spectroscopy diagnosis indicated that many excited argon atoms were distributed almost symmetrically in the lateral direction of the plasma. The concentration variations of reactive species relative to the gas flow rate and discharge current were also examined. ? 2013 AIP Publishing LLC.Accession Number: 20133416636446 -
Record 177 of
Title:Design of a novel LED collimating element based on freeform surface
Author(s):Yan, Xing-tao(1,2); Yang, Jian-feng(1); Xue, Bin(1); Zhang, Guo-qi(3); Bu, Fan(1,2)Source: Optoelectronics Letters Volume: 9 Issue: 1 DOI: 10.1007/s11801-013-2331-0 Published: January 2013Abstract:A novel element for collimating LED light is designed based on non-imaging optics. It is composed of a refraction lens and a reflector. The upper surface of the lens is freeform and calculated by geometrical optics and iterative process. The lens makes the rays in the range of 0°-45° from the optical axis collimated. The rays in the range of 45°-90° from the optical axis are collimated by the reflector. The inner surface of the reflector is parabolic with its focus located in the LED chip. The designed element is applicable to LED source of any emitting type. For a certain application, the simulation results of the designed element in Tracepro show that it has a very compact structure and good collimating performance. Just investigating the loss in the lens surfaces, this element has high light output efficiency of nearly 99%. Most lighting area radii are no more than 20 mm when the illuminated plane is 5 m away from the LED source. ? 2013 Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.Accession Number: 20130315915562 -
Record 178 of
Title:All-reflective optical bifocal zooming system without moving elements based on deformable mirror for space camera application
Author(s):Zhao, Hui(1); Fan, Xuewu(1); Zou, Gangyi(1,2); Pang, Zhihai(2); Wang, Wei(1); Ren, Guorui(1); Du, Yunfei(1); Su, Yu(1)Source: Applied Optics Volume: 52 Issue: 6 DOI: 10.1364/AO.52.001192 Published: February 20, 2013Abstract:The space camera with variable focal length is capable of capturing images with variable resolution and variable field of view. This is useful for space-borne reconnaissance because the camera can switch between coarse and fine reconnaissance flexibly. However, the traditional optical zooming relies on moving elements which might influence the momentum balance of the satellite platform. Therefore, we present a prototype design using the piezo deformable mirror (PDM) to realize an all-reflective optical bifocal zooming system. By changing the curvature radius of the PDM, the focal length can be switched between 48 and 192 mm without moving elements involved. With the focal length experiencing 4× magnification, the system performance is still approaching diffraction-limited performance, and the maximum stroke of the PDM is also within its physical limits. Experiments demonstrate that the principle is correct and the design is successful. ? 2013 Optical Society of America.Accession Number: 20131016086788 -
Record 179 of
Title:Image denoising algorithm via spatially adaptive bilateral filtering
Author(s):Qi, Min(1); Zhou, Zuo Feng(2); Liu, Jing(3); Cao, Jian Zhong(2); Wang, Hao(2); Yan, A Qi(2); Wu, Deng Shan(2); Zhang, Hui(2); Tang, Li Nao(3)Source: Advanced Materials Research Volume: 760-762 Issue: DOI: 10.4028/www.scientific.net/AMR.760-762.1515 Published: 2013Abstract:The classical bilateral filtering algorithm is a non-linear and non-iterative image denoising method in spatial domain which utilizes the spatial information and the intensity information between a point and its neighbors to smooth the noisy images while preserving edges well. To further improve the image denoising performance, a spatially adaptive bilateral filtering image deonoising algorithm with low computational complexity is proposed. The proposed algorithm takes advantage of the local statistics characteristic of the image signal to better preserve the edges or textures while suppressing the noise. Experiment results show that the proposed image denoising algorithm achieves better performance than the classical bilateral filtering image denoising method. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20134416938014 -
Record 180 of
Title:Design of large aperture off-axis catadioptric middle infrared continuous zoom system
Author(s):Jiang, Kai(1,2); Zhou, Sizhong(1); Wang, Yanbin(1); Duan, Jing(1); Zhao, Rui(2); Zhang, Hengjin(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 9 DOI: Published: September 2013Abstract:On the basics of a cool 320 × 240 detector with staring focal plane array, a large aperture off-axis catadioptric middle infrared continuous zoom system was designed. The system worked at 3.7-4.8 μm which achieved the zoom of 250 mm to 2 000 mm and F number of 4. The optical system was divided into two segments. Firstly, an off-axis aspheric non-power system as the front system was designed. Then the continuous zoom lens which matched with the non-power system as the back system was designed. Because of the material constraint, the refractive zoom system could not realize large aperture. Coaxal catadioptric zoom system had great block ratio. And three mirrors zoom system could not achieve cold shield efficiency 100%. The off-axis catadioptric zoom system cold account for forenamed limitation. The system cold offer a high resolution and excellent images, and its cold shield efficiency is 100%. The system satisfies the design requirements.Accession Number: 20134817040201