2014
2014
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Record 349 of
Title:Improved non-uniformity correction algorithm based on integration time Calibration for IRFPA
Author(s):Leng, Han-Bing(1); Zhou, Zuo-Feng(1); Yi, Bo(1); Zhang, Jian(1); Yan, A-Qi(1); Wang, Hao(1); Cao, Jian-Zhong(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 1 DOI: 10.3788/gzxb20144301.0110002 Published: January 2014Abstract:The infrared image quality and temperature resolution is degraded significantly by the non-uniformity response of infrared focal pattern array. Calibration-based and scene-based non-uniformity correction algorithms provide feasible way to handle this problem. Due to its simplicity and accuracy, traditional blackbody calibration-based non-uniformity correction method is widely used but with the disadvantage of highly dependence on the existence of blackbody and its temperature control equipment to provide uniform irradiances. In this paper, an improved two-level non-uniformity correction algorithm based on integration time calibration was proposed. Given the irradiance, the different response data is first obtained through integration time variation. Then the least square method is used to estimate the initial gain coefficients and bias coefficients for two point correction algorithm. Finally, the one point correction coefficients are estimated throuth two point correction of different response data. Experimental results show that the proposed algorithm has the merits of low complexity, high precision, excellent non-uniformity correction performance, and can easily be integrated into hardware platform.Accession Number: 20141017430473 -
Record 350 of
Title:Algorithm of laser spot detection based on optimal arc
Author(s):Cao, Shikang(1); Li, Dongjian(1); Xu, Ruihua(1); Wang, Wei(1); Wang, Zhengzhou(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 10 DOI: Published: October 25, 2014Abstract:Laser spot detection is the key technique used in optical measurement, and widely used in optical measurement system, optical automatic alignment system and laser communication target tracing. In order to improve the optical measurement and anti-interference of spot center and radius, a kind of laser spot center detecting algorithm was put forward based on the optimal arc, according to the symmetry of a circle, the algorithm overcame the interference edges, and then selected the arc with good sysmmetry as the optimal arc to provid the fitting data, calculated center and radius of a circle by using the least squraes method. And it was compared with other commonly used algorithms. Experiments show that the proposed algorithm has high orientation precision for the center and radius, fast speed, and can improve the anti-interference of testing center. The algorithm is suitable for real-time detection. ?, 2014, Chinese Society of Astronautics. All right reserved.Accession Number: 20144900285859 -
Record 351 of
Title:Theoretical and experimental investigations of a nanotube-mode-locked stretched-pulse fiber laser
Author(s):Guo, J.(1)Source: Laser Physics Volume: 24 Issue: 6 DOI: 10.1088/1054-660X/24/6/065104 Published: June 2014Abstract:We report the generation of stretched pulses in a passively mode-locked fiber laser based on a single-wall carbon nanotube saturable absorber. The spectral bandwidth and pulse duration of the single stretched pulse are ～25nm and ～1.43ps, respectively. By increasing the pump power and adjusting the polarization state, bound-state stretched pulses are delivered from the fiber laser. The pulse-pulse separation and wavelength spacing of the bound-state pulses are ～7.8ps and ～1nm, respectively. Numerical simulations reproduce the experimental results and agree well with the experimental observations. ? 2014 Astro Ltd.Accession Number: 20142617868981 -
Record 352 of
Title:Optimization design method of cam curve for zoom lens
Author(s):Chen, Weining(1); Yang, Hongtao(1); Liu, Wei(1); Fan, Zheyuan(1); Zhang, Zhaohui(1); Zhou, Zuofeng(1); Liu, Guangsen(1); Lei, Yangjie(1); Zhu, Qing(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 5 DOI: Published: May 2014Abstract:Zoom cam is a pivotal part used for driving every lens group in zoom lens, the design result of cam curve is decisive importance for motion property and system precision as well as system imaging in zoom system, therefore, zoom cam design is an important part of the zoom lens design, a fine cam performance is the basic requirements to reach lens design of image quality goal and optical zoom process. In order to design a excellent curve form to ensure the pressure angle was smaller, make the process stability and movement smooth fluent, reduce the zoom systems driving moment, and ensure a stability zoom imaging, in the cam design process, we constructed functions which were driving moments of variable group and compensation group with their own pressure angle. Then, combination goal optimization function was built, optimal values of variable group curve pressure angle and compensation group curve pressure angle were optimized and calculated. Optimization results show that the cam drive moment significantly reduces, and improve the overall performance of zoom cam is improved.Accession Number: 20142617873676 -
Record 353 of
Title:Optimized design of automatic panoramic images mosaic
Author(s):Yang, Lei(1); Cao, Jianzhong(1); Tang, Linao(1); Gao, Bo(1); Wang, Hua(1); Guo, Huinan(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 3 DOI: Published: March 2014Abstract:An optimized algorithm of automatic panoramic image mosaic was presented based on time and frequency domains. Firstly, the improved phase correlation method was used to sort the panoramic image sequence automatically and then determine the overlap region. In order to reduce the false match rate of the corner, the brightness of the overall image was adjusted automatically according to the overlap region's pixel mean. Then, an improved Harris operator was adopted to extract corners (with no need to set threshold value manually), the initial feature points pairs were obtained by the bidirectional greatest correlative coefficient and the false feature point pairs were rejected by RANSAC algorithm. Finally, the nonlinear smoothing algorithm was adopted to fuse the overlap regions of the image. The experimental results show that optimization algorithm is simple and effective in the sorting process. Compared with the existing algorithm, the optimization algorithm proposed at present makes a great progress in the success rate and the efficiency in the matching and extracting process of feature points. The stitched image is with great clarity, soundness and stitching accuracy.Accession Number: 20142217774755 -
Record 354 of
Title:Phase retrieval using spatially modulated illumination
Author(s):Gao, Peng(1,2); Pedrini, Giancarlo(1); Zuo, Chao(1,3); Osten, Wolfgang(1)Source: Optics Letters Volume: 39 Issue: 12 DOI: 10.1364/OL.39.003615 Published: June 15, 2014Abstract:In this Letter, we propose a method for retrieving the phase of a wavefront from the diffraction patterns recorded when the object is sequentially illuminated by spatially modulated light. For wavefronts having a smooth phase, the retrieval is achieved by using a deterministic method. When the phase has discontinuities, an iterative process is used for the retrieval and enhancement of the spatial resolution. Both the deterministic and iterative phase reconstructions are demonstrated by experiments. ? 2014 Optical Society of America.Accession Number: 20142617869844 -
Record 355 of
Title:Color management of sRGB color space for HDR digital camera
Author(s):Guo, Huinan(1); Cao, Jianzhong(1); Wang, Hua(1); Zhang, Jian(1); Yang, Hongtao(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: DOI: Published: December 25, 2014Abstract:Digital imaging devices require color space characterization while transferring or showing image between various devices which is a crucial part of color management for digital devices. In order to keep the color reproduction ability for output image, a high dynamic range digital (HDR) camera requires characterization based on the device properties. For existing characterization algorithms, which are in most cases for 8-bit-digital cameras, the processes of transformation matrix calibration are involved in some complex approaches, which are easy to cause system errors and influence the precision of color space transformation matrix. Accordingly, a color management approach was proposed for a high dynamic range colorful digital camera that using a color space mapping from camera RGB space to CIE1931 XYZ color space to estimate the function relation between two color spaces and using the least square method to achieve color matrix calibration. Eventually the camera RGB color space was transformed to sRGB standard color space which achieves characterization for HDR camera. Experimental results show that this method is of good robustness and easy to realize as well as the mean square error is less than 0.08. ?, 2014, Chinese Society of Astronautics. All right reserved.Accession Number: 20151400699944 -
Record 356 of
Title:Upgrading optical information of rotating mirror cameras
Author(s):Li, Jingzhen(1); Sun, Fengshan(2); Huang, Hongbin(1); Gong, Xiangdong(1); Chen, Hongyi(1); Lu, Xiaowei(1); Cai, Yi(1)Source: Review of Scientific Instruments Volume: 85 Issue: 11 DOI: 10.1063/1.4900404 Published: November 1, 2014Abstract:To date, rotating mirror (RM) cameras still serve as indispensable imaging equipment for the diagnosis of microsecond transient processes due to their excellent characteristics. This paper, for upgrading the optical information capacity of the cameras, presents the new optical acceleration principle to increase the framing frequency or scanning velocity, the new design theory without principle errors instead of the classical theories with some flaws in principle to have applied to design our simultaneous streak and framing rotating mirror camera with continuous access, and the new rotating mirror with novel structure, made of an aluminum alloy, to have considerably reduced lateral deformation of the RM and improved the performance of the camera. ? 2014 AIP Publishing LLC.Accession Number: 20150700513950 -
Record 357 of
Title:Research of joint transform correlator stablization image system based on field programmable gate array
Author(s):Yang, Wencai(1); Fan, Xuewu(1); Wang, Fengtao(1); Yi, Hongwei(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: DOI: 10.3788/AOS201434.s212006 Published: December 1, 2014Abstract:Sensor images are easily blurred by the offset of camera focal plane and the observing targets during push-broom space camera exposure time. In order to obtain higher quality images, this camera system needs image stabilization operation. However, the key is restraining imaging platform vibration and getting precisely trajectory of platform in real-time. The acquisition of platform motion vector in high-speed and accurately in the imaging process has become the focus of the development direction of high resolution imaging. Methods often used to obtain targets motion vector are too slow to get targets trajectory accurately in-real time. A joint transform correlator based on field programmable gate array (FPGA) instead of the one based on Fourier optical transform is designed and the calculation precision is up to 0.1 pixel. ?, 2014, Guangxue Xuebao/Acta Optica Sinica. All right reserved.Accession Number: 20145300387768 -
Record 358 of
Title:Diffraction grating sampling rate measurement noise suppression technology
Author(s):Wang, Wei(1); Li, Dongjian(1); Wang, Zhengzhou(1); Xie, Zhengmao(1); Cao, Shikang(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: DOI: 10.3788/AOS201434.s112005 Published: September 10, 2014Abstract:The sampling rate is an important technical indicator of diffraction grating in high-energy lase device, and for the Poisson noise in the sampling rate measurement and stray light interference, the probe is inconsistent and the combination of noise processing method is proposed. The measurement environment and the statistical properties of the detector output are analyzed by statistical laws averaging methods to reduce the Poisson noise effect on the measurement results. Denoising by the histogram method, the influence of stray light is suppressed. By mutual targets, the interference caused by the inconsistencies of detector is reduced. Test results show that the sampling rate measurement relative average deviation is 0.297% and measurement standard deviation is 1.22%. The sampling rate measurement relative average deviation is better than 0.4% and measurement standard deviation is better than 2%, which meet all requirements for sampling test. The method provides a new noise suppress technical means for the measurement of the diffraction grating sampling rate and has been applied and verified in a large aperture diffraction grating comprehensive diagnosis platform.Accession Number: 20144100087999 -
Record 359 of
Title:Parameter estimation of digital communication signal
Author(s):Shen, Chao(1); Gao, Wei(1); Song, Zongxi(1); Yao, Tong(1); Li, Bin(1)Source: Proceedings - 2014 IEEE Workshop on Advanced Research and Technology in Industry Applications, WARTIA 2014 Volume: Issue: DOI: 10.1109/WARTIA.2014.6976464 Published: December 4, 2014Abstract:Direct spread spectrum signal with high anti-interference property, It has the characteristics of pseudo noise. Research on direct spread spectrum signal parameter estimation has important practical significance. According to the transmission characteristics of direct spread spectrum signal, using the time domain correlation method to estimate pn code period and using the frequency domain smooth periodogram estimate chip rate, and using matrix decomposition method to restore the pseudo-code sequence, completed parameter estimation of direct spread spectrum signal. ? 2014 IEEE.Accession Number: 20152901042738 -
Record 360 of
Title:A new type laser imaging system of underwater wake bubbles
Author(s):Xi-Zhan, Liu(1); Yan-Bo, Xue(1)Source: Applied Mechanics and Materials Volume: 543-547 Issue: DOI: 10.4028/www.scientific.net/AMM.543-547.2505 Published: 2014Abstract:Considering the difficulties in the wake bubbles imaging, a wake bubbles measurement system was presented based on the combination of high speed photography and laser sheet scanning technology. In this system, laser sheet was used to illuminate the wake zone to avoid the image stacking of bubbles. Because the particle size of bubbles was in a wide range(10~500um), three switchable magnification lenses were designed for the bubbles imaging. the test results show that th image quality is good and this system satisfies technical requirements. ? (2014) Trans Tech Publications, Switzerland.Accession Number: 20141717625155