2015
2015
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Record 253 of
Title:Research on optical scattering characteristics of high altitude balloon in near space
Author(s):Jing, Nan(1,2); Li, Chuang(1); Zhou, Nan(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 4 DOI: 10.3788/AOS201535.0429001 Published: April 10, 2015Abstract:Optical scattering characteristics of high altitude balloon in near space are researched based on the fundamental radiation theory in applied optics. Facet of balloon in near space is created according to the general idea of coordination transformation and surface mesh-creation. A bidirectional scattering distribution function (BSDF) model is deduced by summing transparent object all scattering components, including specular reflective, near-specular reflective, diffuse reflective and random diffuse reflective components. A mathematical model of scattering characteristics of balloon in near space is built. An atmospheric modeling tool, MODTRAN, is used to model background radiance in the range of 3~5 μm and 8~14 μm and radiance of balloon in the range of 0.24~2.4 μm. The results show that the high altitude balloon radiance is 2.28 × 10-3 W/(cm2?μm·sr), whose calculation error is 10.6% in use of BSDF model, and relative to bidirectional reflection distribution function (BRDF) model, the accuracy has an improvement of 2%. The modeling method of scattering characteristics of balloon in near space agrees with the modeling results, which proves the correctness of mathematical model. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152300916646 -
Record 254 of
Title:Thermal design for the optical-structure system of high resolution high-altitude camera
Author(s):Shi, Kui(1); Yang, Hong-Tao(1,2); Chen, Wei-Ning(1); Fan, Zhe-Yuan(1,2); Zhang, Gao-Peng(1); Wu, Deng-Shan(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 44 Issue: 5 DOI: 10.3788/gzxb20154405.0522005 Published: May 1, 2015Abstract:To guarantee the image quality of a high-altitude camera in extreme low temperatures, thermal design for camera optical system was done by combined passive thermal control with active thermal control. Polyimide insulation material is used for passive thermal control, increasing the camera's thermal resistance between internal structures and external environment, and decreasing the influence of the external cryogenic environment on the temperatures of camera lens. The method of using electric heating film to heat camera lens was adopted as an active thermal control means. The heat transfer model of the lens in the optical system was built in the WorkBench finite element software with heating power loads, thermal convection loads and thermal radiation loads considered, and steady-state thermal analysis was carried out. It turned out that, the temperature of the camera optical system was controlled in the range of 18℃~22℃ when the heating power of six heating zones was 12, 17, 22, 17, 10, 13 W, and the thermal control result meted the design requirements. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152500946861 -
Record 255 of
Title:Prediction trajectory of moving target based on parameter identify in RLS filtering with forget factor
Author(s):Yin, Yili(1,2); Tian, Yan(1); Li, Zhang(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9677 Issue: DOI: 10.1117/12.2202377 Published: 2015Abstract:A moving target should be missing from a photoelectric theodolite tracker, when the clouds and other special conditions encountered in the course of a theodolite tracking a moving object, and this condition should cause the interruption of tracking process. In view of this problem, an algorithm based on the frame of parameter identification and rolling prediction to trajectory was presented to predicting the target trajectory when it missing. Firstly, the article makes a specification of photoelectric theodolite and it operating mechanism detailed. The reasons of flying target imaging disappear from the field of theodolite telescope and the traditional solution to this problem, the least square curve fitting of trajectory quadratic function of time, were narrated secondly. The algorithm based on recursive least square with forget factor, identify the parameters of target motion using the data of position from single theodolite, then the forecasting trajectory of moving targets was presented afterwards,in the filtering approach of past data rolling smooth with the weight of last procedure. By simulation with tracking moving targets synthetic corner from a real tracking routine of photoelectric theodolite, the algorithm was testified, and the simulation of curve fitting a quadratic function of time was compared at the last part. ? COPYRIGHT SPIE 2015.Accession Number: 20155201714912 -
Record 256 of
Title:Active control of beams by metallic nanoslit array lens with movable dielectric substrate
Author(s):Jia, Sen(1); Wang, Xianhua(1); Wu, Yiming(1); Xiao, Maosen(1); Fan, Pengge(1); Wang, Zhiyong(2)Source: Applied Physics Express Volume: 8 Issue: 6 DOI: 10.7567/APEX.8.062001 Published: June 1, 2015Abstract:We proposed a plasmonic structure consisting of uniform metallic nanoslits with a movable dielectric substrate for subwavelength beam manipulation. In this structure, the phase of incident light can be modulated beforehand by the substrate before bumping the metal slits; therefore, the shape of transmitted light from nanoslits can be actively controlled by changing the substrate profile. According to this idea, plasmonic lenses with different functions, such as focusing light to two points, focus length variation, and beam deflection, are designed and investigated numerically. The proposed structure has a unique advantage of multifunction and reduces the difficulty in fabrication. ? 2015 The Japan Society of Applied Physics.Accession Number: 20152400935224 -
Record 257 of
Title:Enhanced slow light in microfiber double-knot resonator with a Sagnac loop reflector
Author(s):Xu, Yiping(1,2); Ren, Liyong(1); Wang, Yingli(1); Kong, Xudong(1,2); Liang, Jian(1); Ren, Kaili(1,2); Lin, Xiao(1,2)Source: Optics Communications Volume: 350 Issue: DOI: 10.1016/j.optcom.2015.04.027 Published: September 1, 2015Abstract:We propose a theoretical model to describe the light-propagation property of the microfiber double-knot resonator with a Sagnac loop reflector. The mathematical relationships between the reflection light field and the input one of this structure are deduced. Numerical simulations indicate that, comparing with the group time delay in the microfiber double-knot resonator, the one in the same resonator but with a Sagnac loop reflector can be enhanced considerably. For comparison, microfiber double-knot resonators with and without a Sagnac loop reflector are both fabricated. Corresponding comparison experiments are performed, which indeed demonstrates the theoretical prediction. A group time delay of about 61 ps is achieved experimentally in the resonator with a Sagnac loop reflector, while in the same resonator but without a Sagnac loop reflector it is only about 30 ps. ? 2015 Elsevier B.V. All rights reserved.Accession Number: 20151600747553 -
Record 258 of
Title:Study on writing double line waveguide in Yb3+: phosphate glass by femtosecond laser
Author(s):Tang, Wenlong(1,2); Liu, Shuang(1,2); Cheng, Guanghua(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 42 Issue: 4 DOI: 10.3788/CJL201542.0406005 Published: April 10, 2015Abstract:By using femtosecond laser with repetition frequency of 50 kHz, center wavelength of 790 nm, and pulse width of 140 fs, double line waveguides are inscribed in Yb3+ doped phosphate glass. The influences of double-line separation, laser pulse energy and writing speed on the waveguide formation are investigated and the near-field modes of waveguides written by different laser parameters are measured. The experimental results show that the waveguide has good property of guiding under the writing conditions of double-line separation of 35 mm, pulse energy of 1.0 mJ and scanning speed of 600 mm/s. By using near-field mode, bivariate distribution of the waveguide refractive index is reconstructed with the maximum refractive index change of 1.5×10-4. The propagation loss of the waveguide is 1.56 dB/cm by testing with the scattering technique. The phenomenon of polarization guiding is discovered from the waveguide. The waveguide can guide the laser with polarization parallel to the direction of double line and the laser with polarization perpendicular to the direction of double line cannot be guided. ?, 2015, Science Press. All right reserved.Accession Number: 20152400928307 -
Record 259 of
Title:Er3+: 'water-free' fluorotellurite glass waveguides written by femtosecond laser
Author(s):Liu, Shuang(1,2); Tang, Wenlong(1,2); Cheng, Guanghua(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 4 DOI: 10.3788/AOS201535.0413001 Published: April 10, 2015Abstract:By femtosecond laser with repetition rate of 1 kHz, central wavelength of 800 nm and pulse width of 120 fs, Type I (single line) and depressed circular cladding waveguides in Er3+ doped 'water-free' fluorotellurite glass are transversely written with slit shaping technology, respectively. The impact of the processing conditions on the waveguides' formation is systematically studied, and the waveguides with better guiding mode are obtained. Refractive index profile is reconstructed by intensity distribution of the near-field mode, and the largest positive refractive index change for Type I waveguide is about 1×10-4, slightly smaller than that (1.9×10-4) of depressed cladding waveguide. By using the scattering technique, the propagation loss of Type I waveguide is about 1.04 dB/cm. The loss of depressed cladding waveguide is less than 1.88 dB/cm by measuring insertion loss. Therefore, Er3+ doped 'water-free' fluorotellurite glass waveguides inscribed by femtosecond laser are promising candidates for the development of integrated laser resources. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152300916622 -
Record 260 of
Title:High speed random number generator based on digitizing bandwidth-enhanced chaotic laser signal
Author(s):Yan, Qiurong(1); Cao, Qingshan(1); Zhao, Baosheng(2); Zhang, Hua(1); Liao, Qinghong(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 42 Issue: 11 DOI: 10.3788/CJL201542.1102004 Published: November 10, 2015Abstract:A high speed random number generator based on digitizing bandwidth-enhanced chaotic laser signal is proposed and demonstrated. In order to remove the weak periodicity in optical feedback chaotic semiconductor laser signal, the optical feedback chaotic semiconductor laser is injected into another semiconductor laser to obtain a bandwidth-enhanced chaotic laser signal. The bandwidth-enhanced chaotic laser signal is converted using an 8-bit high speed analog-to-digital convertor to achieve generating multi bits by each sampling point. In order to remove the bias existing in original extracted random bits and improve the efficiency of random bit generation, fieldprogrammable gate array based secure hash algorithm 256 is proposed to extract random bit. Due to the use of 4-channel parallel processing technology, online random number generation rate of 2.94 Gbit/s is obtained and each sample could produce average 4.65 random bits. The obtained random numbers pass all the tests in random testing program of ENT and STS. ? 2015, Chinese Laser Press. All right reserved.Accession Number: 20155301741635 -
Record 261 of
Title:Fast hyperspectral anomaly detection via high-order 2-d crossing filter
Author(s):Yuan, Yuan(1); Wang, Qi(2); Zhu, Guokang(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 53 Issue: 2 DOI: 10.1109/TGRS.2014.2326654 Published: February 2015Abstract:Anomaly detection has been an important topic in hyperspectral image analysis. This technique is sometimes more preferable than the supervised target detection because it requires no a priori information for the interested materials. Many efforts have been made in this topic; however, they usually suffer from excessive time cost and a high false-positive rate. There are two major problems that lead to such a predicament. First, the construction of the background model and affinity estimation are often overcomplicated. Second, most of these methods have to impose a stringent assumption on the spectrum distribution of background; however, these assumptions cannot hold for all practical situations. Based on this consideration, this paper proposes a novel method allowing for fast yet accurate pixel-level hyperspectral anomaly detection. We claim the following main contributions: 1) construct a high-order 2-D crossing approach to find the regions of rapid change in the spectrum, which runs without any a priori assumption; and 2) design a low-complexity discrimination framework for fast hyperspectral anomaly detection, which can be implemented by a series of filtering operators with linear time cost. Experiments on three different hyperspectral images containing several pixel-level anomalies demonstrate the superiority of the proposed detector compared with the benchmark methods. ? 2014 IEEE.Accession Number: 20143518100087 -
Record 262 of
Title:Decoding algorithms and spatial resolution Monte Carlo simulation of cross strip anode for UV astronomy
Author(s):Deng, Guobao(1,2); Zhu, Xiangping(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9449 Issue: DOI: 10.1117/12.2075999 Published: 2015Abstract:The development decoding algorithms of two-dimensional cross strip anodes image readouts for applications in UV astronomy are described. We present results with Monte Carlo simulation by GEANT4 toolkit, the results show that when the cross strip anode period is 0.5mm and the electrode width is 0.4mm, the spatial resolution accuracy is sufficient to reach better than 5 μm, the temporal resolution accuracy of the event detection can be as low as 100 ps. The influences of the cross strip detector parameters, such as the anode period, the width of anode fingers (electrode), the width of the charge footprint at the anode (determined by the distance and the field between the MCP and the anode), the gain of the MCP and equivalent noise charge (ENC) are also discussed. The development decoding algorithms and simulation results can be useful for the designing and performance improvement of future photon counting imaging detectors for UV Astronomy. ? 2015 SPIE.Accession Number: 20151100635527 -
Record 263 of
Title:Slow-light effect in microfiber double-knot resonator with a parallel structure
Author(s):Xu, Yi-Ping(1,2); Ren, Li-Yong(1); Wang, Ying-Li(1); Kong, Xu-Dong(1,2); Liang, Jian(1); Ju, Hai-Juan(1); Qiao, Dun(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 44 Issue: 5 DOI: 10.3788/gzxb20154405.0506002 Published: May 1, 2015Abstract:In order to study the slow-light effect in the microfiber based resonator, a microfiber double-knot resonator with a parallel structure was designed and fabricated. Based on the theories of the ring resonator and the direction coupler, the theoretical model of the microfiber double-knot resonator with a parallel structure was proposed, the direction of the light-field propagation and coupling in the resonator was analyzed, the mathematic expression between the output light and the input one in the resonator was deduced, and the expression of the group delay time was also obtained. By numerical simulating method, the spectra of the transmission and the group delay time were given, the corresponding relationship between group delays and resonant wavelengths of the transmission spectrum in the resonator was analyzed. The numerical result indicates that a large group delay can be obtained at the resonant wavelength with a large extinction ratio in the resonator. In experimental, a microfiber double-knot resonator with a parallel structure was fabricated, the transmission spectrum of the fabricated resonator was well consistent with the theoretical simulation, indicating that the theoretical analysis is correct. Employing the pulse-delay method in the Oscilloscope, a measuring system of the slow-light delay in the resonator was set up. A group delay of about 75 ps in the fabricated resonator is achieved, which is larger than the reported value. The resonator could be beneficial to applicating in data delay lines, optical switches and optical memories, etc. ?, 2015, Chinese Optical Society. All right reserved.Accession Number: 20152500946844 -
Record 264 of
Title:Research on large dynamic range streak camera based on electron-bombarded CCD
Author(s):Zhu, Min(1,2); Tian, Jin-Shou(1); Wen, Wen-Long(1); Wang, Jun-Feng(1); Cao, Xi-Bin(1); Lu, Yu(1); Xu, Xiang-Yan(1); Sai, Xiao-Feng(1); Liu, Hu-Lin(1); Wang, Xing(1); Li, Wei-Hua(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 64 Issue: 9 DOI: 10.7498/aps.64.098501 Published: May 5, 2015Abstract:In order to detect the weaker on greater span of light signals, the dynamic range, spatial resolution, and the signal to noise ratio of the streak camera need to be improved to meet further diagnostic requirements in scientific area of materials, biology, information, semiconductor physics and energy, etc. Therefore, we design a streak camera with a larger dynamic range based on electron-bombarded CCD. Using the rectangle-framed electrode and electric quadruple lens in the streak camera can reduce its space charge effect and shorten the space charge interaction time by improving electron accelerating voltage to minimize the electron transit time. Using a back-illuminated CCD, which is based on the electron bombardment readout technology as image device to replace the traditional intensified CCD can shorten the chain of image conversion and greatly reduce the image degradation in the conversion of ultrafast diagnostic equipment. The signal to noise ratio, spatial resolution and dynamic range of the streak camera may gain improvement. Experimental results show that the static spatial resolution is better than 35 lp/mm and the dynamic spatial resolution is up to 20 lp/mm. Deflection sensitivity is 60.76 mm/kV and dynamic range reaches 2094: 1. Nonlinear scanning speed is 5.04%. EBS gain of the streak camera can be over 3000. ?2015 Chinese Physical SocietyAccession Number: 20152100871875