2012
2012
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Record 181 of
Title:Monomode optical planar and channel waveguides in Yb3-doped silicate glasses formed by helium ion implantation
Author(s):Liu, Chun-Xiao(1,2); Cheng, Shu(3); Zhao, Jin-Hua(4); Li, Wei-Nan(2); Wei, Wei(2,5); Peng, Bo(2,5)Source: Optics and Laser Technology Volume: 44 Issue: 8 DOI: 10.1016/j.optlastec.2012.04.033 Published: November 2012Abstract:We report on the fabrication of optical planar and channel waveguides in Yb3-doped silicate glasses by triple-energy helium ion implantation at a total dose of 6×1016 ions/cm2. The dark mode spectroscopy of the planar waveguide was measured using a prism coupling arrangement. The near-field mode profiles of the planar and channel waveguides were obtained with an end-face coupling system. The refractive index profile was reconstructed using the intensity calculation method. The results indicate that a refractive index enhanced region as well as an optical barrier has been created after the beam process. After post-implantation treatments at 260 °C for 1 h and 310°C for 30 min, the channel waveguides possessed a propagation loss of ～0.9 dB/cm. The acceptable guiding properties suggest that further waveguide lasers may be realized on the He-implanted Yb 3-doped silicate glass waveguides. ? 2012 Elsevier Ltd.All rights reserved.Accession Number: 20122215079413 -
Record 182 of
Title:Optical design of wake bubbles measurement system
Author(s):Li, Tenglong(1,2); He, Junhua(1); Xie, Zhengmao(1); Liu, Xizhan(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 9 DOI: Published: September 2012Abstract: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, three switchable magnification lenses were designed for the bubbles imaging. Lenses were split into front and rear groups, with parallel rays transmitting between them. With the sweeping of laser sheet, the image information of bubbles in a volume could be sampled. Moreover, by keeping the front group moving synchronously with the laser sheet, bubbles could always image clearly when the laser sheet sweeps. The influence on image quality, the determination of laser sheet thickness and the system distortion correction were also discussed when laser sheet sweeps. Therefore, the design results show that the image quality is good and this system satisfies technical requirements.Accession Number: 20124915755282 -
Record 183 of
Title:Super-resolution reconstruction of Chang'e-1 satellite CCD stereo camera images
Author(s):Zhang, Lei(1,2); Yang, Jianfeng(1); Xue, Bin(1); Liang, Shitong(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 2 DOI: Published: February 2012Abstract:Considering the limited space resolution of the Chang'e-1 satellite's CCD stereo camera, MAP (maximum a posteriori probability) algorithm is used for lunar images super-resolution reconstruction. Imaging model of the Chang'e-1 satellite CCD stereo camera, analyses chief factors which determine the image quality in brief, and establishes appropriate model for super-resolution reconstruction are introduced. According to this reconstruction model, the error-parameter analysis was used to estimate the point spread function (PSF) of dynamic imaging system of the Chang'e-1 satellite CCD stereo camera firstly. Secondly, the estimated PSF was applied to the objective function established by the MAP algorithm, and the conjugate gradient method (CGM) was used to solve the extreme value of the function. Thirdly, the super-resolution reconstructions of the single frame normal lunar images were prograrmmed on VC software platform. Finally, the reconstructions through entropy, definition and spectrum were evaluated. Results show that the reconstructions quality is of great.Accession Number: 20121514940926 -
Record 184 of
Title:Optimizing design of baffle in the ground-based IR optical system
Author(s):Shang, Ling(1,2); Liu, Zhaohui(1); She, Wenji(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 5 DOI: Published: May 2012Abstract:A method of optimizing design of baffle was proposed to decrease the inner irradiation of the ground-based infrared optical system. The first order part of the conventional baffle was substituted by several reflective surfaces which were perpendicular to each other. Because the reflective surfaces could retro-reflect the irradiated light, the out-of-field stray light was suppressed. Also the reflective surfaces were of low emissivity, the stray light induced by inner irradiation was decreased. This method of optimizing the baffle was introduced in detail. Taking a ground-based infrared optical system for example, the point source transmittance (PST) and the inner irradiation of the baffle were calculated by the TRACEPRO software. The results show that, compared with the conventional one, the inner irradiation of optimized baffle is reduced about one grade and the level of PST could satisfy the requirement.Accession Number: 20122915259938 -
Record 185 of
Title:Research on object signal sampling and reconstruction based on laser beat frequency
Author(s):Zhang, Yu(1,2); Luo, Xiujuan(1); Cao, Bei(1); Xia, Aili(1); Si, Qingdan(1,2)Source: Procedia Engineering Volume: 29 Issue: DOI: 10.1016/j.proeng.2012.01.325 Published: 2012Abstract:The observation of an object traditionally relies on the scale of optical system and the resolution is often limited by the diameter of telescope. Based on the laser interference technology, we adopt a new signal sampling method with which we sample the spectrum information by laser beat frequency. The overlapped beams interfere together and generate a series of fringes across the target. Different spectrum components of target are sampled by fringes with different spatial frequency. Then we will reconstruct the target image through inverse Fourier Transform. This method break through the difficulty that observation resolution was limited by the scale of optical system. ? 2011 Published by Elsevier Ltd.Accession Number: 20121214882972 -
Record 186 of
Title:Measuring method of coordinator azimuth angle based on photoelectric sensor
Author(s):Xu, Feng(1,2); Wu, Yiming(1); Wang, Weifeng(1); Bai, Jianming(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 5 DOI: Published: May 2012Abstract:Aiming at the deficiency of traditional measuring method for coordinator azimuth angle, a non-contact method of detecting graphics information on the surface of gyro rotor based on photoelectric sensor was presented. Firstly, the overall project design of measuring method based on photoelectric sensor was given. Secondly, static model and dynamic model of coordinator gyro rotor were established. Research was focused on the surface pattern of gyro rotor, and the principle formula was deduced through theoretical analysis. Finally, with simulation analysis of two aspects of error transfer factor and linearity, most important pattern parameter was selected properly. The research result shows that it is possible to realize the linearity less than 5‰ and measuring accuracy up to minute of arc in the range of ±40 degrees by measuring method of coordinator azimuth angle based on photoelectric sensor, which is suitable for engineering application.Accession Number: 20122915259973 -
Record 187 of
Title:Alignment method of coaxial eccentric-pupil three-mirror system
Author(s):Zhang, Xuemin(1,2); Han, Juan(1); Duan, Jiayou(1); Wu, Mengyuan(1,2); Wei, Ruyi(1,2)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 39 Issue: 4 DOI: 10.3788/CJL201239.0416003 Published: April 2012Abstract:In order to realize the high accuracy alignment of co-axial eccentric-pupil three-mirror system, and to improve the image quality, the micro-stress installation of large-aperture aspheric mirror and system benchmarking adjusting techniques are investigated. The optical calibration and mechanical calibration of primary mirror, secondary mirror and third mirror are unified by using optical alignment machining. The assembly of three mirrors, also the aberration adjustment of two-mirror system and three-mirror system are realized by the instruct of wavefront aberration distribution which is gained from Zygo interferometer. The pupil of coaxial three-mirror system is eccentric, and the sweeping direction is vertical with the linear charge coupled device (CCD) direction, the system astigmatism brought by the tilting of folded-axis mirror is removed by rotating the folded-axis mirror and trimming the neighboring circle. Alignment results indicate that the image quality targets of optical system's each field-view are achieved, the root mean square (RMS) of optical system is less than 0.07λ, and the modulation transfer function (MTF) is larger than 0.57.Accession Number: 20122515138404 -
Record 188 of
Title:Calculations on optical path difference of a reflecting scanning fourier transform spectrometry based on cube reflector
Author(s):Zhang, Xin Jie(1,2); Yang, Xiao Xu(1); Wang, Wen Fang(1,2)Source: Applied Mechanics and Materials Volume: 226-228 Issue: DOI: 10.4028/www.scientific.net/AMM.226-228.1951 Published: 2012Abstract:Compared with normal reflecting scanning transform Spectrometry, cube-based Spectrometr is a key component in the time-based modulation interference spectrometer, it have more compact structure,using less accessory, easy to fix up, more steadily and more practicality. Calculations on optical path difference (OPD) of spectrometry play an important role in analyzing and improving of the structure. Following the law of Malus and the geometrical relationship of model, get the formula of OPD and the affective factors.The calculation results demonstrate that OPD is closely related to the tilted angel of rotating reflector, the size of cube reflector and the refractive index of reflector. And this kind of spectrometry has the character of high resolution, especial in some spectrum. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20125215834624 -
Record 189 of
Title:Reflective optical zoom system based on deformed mirrors without mechanical moving parts
Author(s):Su, Yu(1); Fan, Xue-Wu(1); Zou, Gang-Yi(1,2); Zhao, Hui(1); Du, Yun-Fei(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 20 Issue: SUPPL. DOI: 10.3788/OPE.20122013.0172 Published: December 2012Abstract:Space cameras with the capability of changing focal length play a very important role in the field of earth obversation. This paper summarizes the investigation and development of reflective optical zooming systems all around the world, then a zoom optical system design method based on Deformed Mirrors(DMs) without any mechanical moving parts is put forward. Considering the superiority of non-coaxial reflective system in realizing high-resolution-large depth of filed imaging, a four-mirror reflective zoom optical system with a large field-of-view (FOV) and a zoom ratio of 4 is designed. The central obscuration is eliminated by making the FOV non-coaxial. The third mirror is a DM, and its curvature is controlled to allow the focal length changed from 0.625 m to 2.5 m. The separate primary mirrors for the different focal positions are used to reduce the optical-power changing range of the DM. The performance of the final optical system achieves diffraction limited.Accession Number: 20132216372302 -
Record 190 of
Title:Fault-tolerant autolanding controller design using neural network
Author(s):Bai, Jian-Ming(1); Rong, Hai-Jun(2)Source: Chinese Control Conference, CCC Volume: Issue: DOI: Published: 2012Abstract:In the paper, a neural control scheme is presented for an UAV automatic landing problem under the failure of stuck control surfaces and severe winds. The scheme incorporates a neural controller which augments an existing conventional controller called Baseline Trajectory Following Controller (BTFC). The neural controller is designed using Single Hidden Layer Feedforward Networks (SLFNs) with additive or Radial Basis Function (RBF) hidden nodes in a unified framework. The SLFNs are trained based on the recently proposed neural algorithm named Online Sequential Extreme Learning Machine (OS-ELM). In OS-ELM, the parameters of hidden nodes (the input weights and biases of additive nodes or the centers and impact factors of RBF nodes) are randomly selected and the output weights are analytically determined based on the sequentially arriving data. Performance of the proposed neural control scheme is evaluated on a typical aircraft autolanding with a single stuck failure of left elevator. The simulation results demonstrate good fault tolerant performance of the proposed neural fault tolerant controller. ? 2012 Chinese Assoc of Automati.Accession Number: 20130716023941 -
Record 191 of
Title:Design of freeform surface LED reflectors for uniform illumination based on compensation method
Author(s):Yan, Xingtao(1,2); Yang, Jianfeng(1); Zhang, Guoqi(3); Bu, Fan(1,2); Zhang, Lei(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 3 DOI: Published: March 2012Abstract:According to the design principle of ideal light source, a method to obtain freeform surface generatrix based on energy compensation and coordinate iteration was proposed. Freeform surface LED reflectors for uniform illumination were designed. Firstly, the geometrical model of illumination system was established in two-dimensional coordinate system, in order to get uniform illumination. The directly incident energies were compensated by the reflected rays. Concretely, the rays were refected into the upper verge of the reflector to the verge area of the target plane, and go down to the bottom of the reflector along with the rays, approaching the middle of the target plane. Based on Snell equation and geometrical relation, choosing the point on the top of freeform surface generator as the initial point, the coordinates of all points on the freeform surface generator were obtained by iteration method, which could be rotated or extended into the freeform surface. The simulations of the designed LED reflectors with Tracepro software show that the illumination uniformity of either the circle or the square target plane is higher than 85%, and the energy efficiency which was affected only by the LED's emitting angle and the reflectivity of the reflector surface can be high. These peculiarity enable LED light source to be applied in wide range lighting system.Accession Number: 20121915007917 -
Record 192 of
Title:Decoding method for the spectral mixing pixels in Hadamard transform spectral imager
Author(s):Xu, Jun(1,2); Hu, Bingliang(1); Feng, Dazheng(3); Fan, Xiaohui(4); Qian, Qingming(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 6 DOI: Published: June 2012Abstract:A sort of engineering Hadamard transform spectral imager based on DMD was introduced. Because the size of individual micromirrors did not match the pixel size of the detector, or for other unavoidable errors in the optical design and the system assembling, a sort of spectral mixing phenomenon appeared on some pixels of the encoded images acquired from the detector. Their encoding principle was described and analyzed. The analysis demonstrated that these spectral mixing pixels could not be decoded by inverse Hadamard transform directly. To decode these spectral mixing pixels accurately and improve the quality of the decoded spectral images, a decoding method for these spectral mixing pixels of the encoded images was proposed. Firstly, a decoding coefficient for the spectral mixing pixel was gotten by directing a beam of laser into the spectral imager to fill the field of view. Then the coefficient was brought into the encoding equation of the spectral mixing pixel to decode all the spectral elements. The experimental results prove the feasibility of the decoding method.Accession Number: 20123715424639