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Record 61 of
Title:Study on the methods of calibrating spectral line position of interference imaging spectrometer
Author(s):Wei, Yu-Tong(1,2); Liu, Shang-Kuo(3); Yan, Ting-Yu(1,2); Li, Qi-Wei(1,2)
Source: Wuli Xuebao/Acta Physica Sinica Volume: 65 Issue: 8 DOI: 10.7498/aps.65.080601 Published: April 20, 2016
Abstract:The principle of interference imaging spectrometer is presented. According to the drift of recovery spectral line position, two representative methods of calibrating the laboratory spectral line position are proposed, and the calibration results and their comparative analyses are given. One method of calibration is to correct the principle, which embarks from parameter selection of interference imaging spectrometer and the analysis of the reason why the spectral line position is drifted. Aiming at the problem that the position of spectral line changes with row, the correction scheme is given to improve the accuracy of spectral line position. For four given laser wavelengths, which are 543.5 nm, 594.1 nm, 612 nm, and 632.8 nm, the root-mean-square (RMS) error of spectral line position is reduced from 28.3914 to 5.5371 after calibration. For the interferometer system which has no dispersion, the accuracy of calibration is better than the dispersion system, and can be the same at all detected wavelengths. In this article, the calibration accuracy of long wave is better than that of short wave, which is dependent on the selection of the initial correction wavelength. This method achieves a kind of universality for interference imaging spectrometer and its calibration parameters provide a convenient way to analyze the instrument indexes. Another calibration method is data processing. It makes up the deficiencies of the method mentioned above: a large number of data are needed and the effect of calibration at short wave is not good enough. The RMS error of spectral line position is reduced to 0.9178, which proves that the calibration has a really high precision. This method is simple and can correct all the detected wavelengths and spectral lines by using two united formula. Though this method is not applicable for all the interference imaging spectrometers, the idea that makes hard things simple is deserving of our attention. We can use it in many other fields. The essence of the method is to change a variable quantity into a slowly varying quantity by algorithms, and then establish the relationship between the slowly varying quantity and the standard value. This idea can always make a substantial increase in efficiency of calibration and has a satisfied accuracy. Each of the two methods has advantages and disadvantages: which method we choose to use is dependent on the effect we want to achieve, and it is better to make their combination. This study provides a theoretical and practical guidance for study, design, modulation, experiment and engineering of interference imaging spectrometers. ? 2016 Chinese Physical Society.
Accession Number: 20162002392013
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Record 62 of
Title:Switch-zoom optical system design of large aperture ground-based photoelectric detection
Author(s):Yan, Peipei(1); Liu, Kai(1); Duan, Jing(1); Jiang, Kai(1); Shan, Qiusha(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9682 Issue: DOI: 10.1117/12.2242255 Published: 2016
Abstract:Binary optics can be used to increase optical performances, decrease size and weight, and decrease systems costs in numerous applications. By means of hybrid diffractive-refractive, a switch-zoom optical system of catadioptric large aperture ground-based photoelectric detection is designed. The characteristic of the system is that it is a compact optical system without moving parts which can get two focal lengths. And the quality of image approaches the diffraction limited. Ritchey-Chrétien (R-C) mirror and a field lens are common for long-focus system and short-focus system. Two refract groups transmitting optical system are used for zooming. In order to satisfy the demand of energy regulation, it is designed afocal beam between field lens and later refract optical system. Filter and variable density plate are placed in it to guarantee the imaging quality. The focal length is 3750mm and F number is 7.5 for the long-focus system, and the focal length is 1850mm and F number is 3.75 for the short-focus system. Former part and later lens of the system are both perfect imaging. They can be fabricated and detected independently. So the design demand can be satisfied better and the imaging quality can be improved. ? 2016 SPIE.
Accession Number: 20164903095191
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Record 63 of
Title:Pressure sensor for Weight-In-Motion measurement based on fiber loop ring-down spectroscopy
Author(s):Yang, Songlin(1,2); Ruan, Chi(1); Wang, Yuntao(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10158 Issue: DOI: 10.1117/12.2246819 Published: 2016
Abstract:In order to resolve the disturbance of external perturbation in Weight-In-Motion (WIM) measurement by traditional methods, a novel pressure sensor for WIM of vehicles based on fiber ring-down spectroscopy is proposed here. A micro-bending sensing head is designed and its working principle is discussed in this paper. The fiber loop ring-down (FLRD) system reveals that the sensing forces applied to the sensing head can be obtained by measuring the ring-down time. Meanwhile, the velocity of vehicles is measured by analyzing two ring-down spectrums in this scheme. Experiment results show that the precision of velocity of vehicles is good and the sensor has a linear response to the applied force. ? 2016 SPIE.
Accession Number: 20170203232353
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Record 64 of
Title:Optical design for large depth of field
Author(s):Shen, Yang(1,2); Wang, Hu(1); Yue, Pan(1,2); Xue, Yaoke(1); Liu, Jie(1); Ye, Shuifu(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9796 Issue: DOI: 10.1117/12.2229621 Published: 2016
Abstract:Optical system with large depth of field and large field of view has been designed. To enforce optical system with focal length of 6 mm to imaging the object with object length of 200mmm-1200mm, accord to the equation of depth of field, in case of the CCD sensor with pixel of 5.5umx 5.5um square area, the entrance pupil diameter to ideal imaging will be 0.423mm. To enlarge the modulation transfer function (MTF) at spatial frequency of 90 lp/mm, the entrance pupil diameter is enlarged to 1mm. After design and optimization, with field of view of 80°, within object length of 200mm - 1200mm, the optical system can imaging well, the modulation transfer function (MTF) at spatial frequency of 90lp/mm is larger than 0.1, the distortion of full field of viewed is less than 3%.The optical system can be widely used in machine vision, surveillance cameras, etc. ? 2016 SPIE.
Accession Number: 20163502747299
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Record 65 of
Title:The degree of polarization modeling with different shapes of the satellite
Author(s):Yao, Dalei(1,2,3); Xue, Jianru(3); Wen, Desheng(1); Qiu, Yuehong(1); Xi, Jiangbo(1,2); Wen, Yan(1); Chen, Zhi(1)
Source: Optik Volume: 127 Issue: 4 DOI: 10.1016/j.ijleo.2015.09.172 Published: February 1, 2016
Abstract:Polarization is one of the important characteristics of the interaction between light and substance, which relates to the shape and the material of the target. To research the effects of the degree of polarization (DOP) caused by different materials, the polarized bidirectional reflectance distribution function (pBRDF) model has been established by the theory of microfacet. But in this model, the scattering effect of polyhedron is ignored. Based on these researches, the DOP model of satellite with different shapes (cuboid, cylinder and sphere) is set up and simulated. The simulating results show that the DOP of satellite relates with the complex refractive index, shape of satellite, incident angle and view angle. It is also proved that the polarization is a reflection of the characteristics of material, shape of satellite, which provides theoretical support for identifying satellite. ? 2015 Elsevier GmbH.
Accession Number: 20160301806178
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Record 66 of
Title:The modular design of large-Aperture zoom system
Author(s):Liu, Kai(1); Jiang, Kai(1); Yan, Peipei(1); Shan, Qiu-Sha(1); Duan, Jing(1); Li, Gang(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10154 Issue: DOI: 10.1117/12.2244007 Published: 2016
Abstract:According to the large aperture, long focal length zoom system design, the structure of the optical system based on the modular concept is proposed. The structure is constituted of an afocal compression telescope and a zoom system. The parts of each other are individually designed. The aberrations of them are independently. Because of this, the alignment of the system and the difficulty of test are greatly reduced. It is easily replaced by changing the zoom system parts, which can achieve other different focal length and ratio. Using afocal compression telescope greatly reduces the radial aperture of the zoom group, simplifies the system structure and reduces the cost. Meanwhile, the variable stop is placed in the vicinity of the primary mirror. It is instead of the zoom system used in floating variable stop. In addition, the problem about large aperture zoom system pupil matching is solved perfectly. In this article, four methods of pupil matching are given and the advantages and disadvantages of them are analyzed. Using this optical structure, a zoom system is designed, which is working in the visible wavelength band with variable focal length between 900mm and 4500mm, 500mm maximum aperture. The axial dimension of the system is less than 650mm. The maximum diameter of zoom system parts is less than 40 mm. Moreover, the distances of the zoom group and compensating group are all less than 60 mm. Besides, the motion curves of each other are given in the article. The Modulation Transfer Function (MTF) values of the system are greater than 0.3 at 48lp/mm across different focal length and field pointing on the axis. The design results show that the imaging quality is excellent, the structure is compact, and the alignment and test are easy. The imaging requirements of zoom system are all satisfied. ? 2016 SPIE.
Accession Number: 20170503310056
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Record 67 of
Title:DSets-DBSCAN: A Parameter-Free Clustering Algorithm
Author(s):Hou, Jian(1,2); Gao, Huijun(3); Li, Xuelong(4)
Source: IEEE Transactions on Image Processing Volume: 25 Issue: 7 DOI: 10.1109/TIP.2016.2559803 Published: July 2016
Abstract:Clustering image pixels is an important image segmentation technique. While a large amount of clustering algorithms have been published and some of them generate impressive clustering results, their performance often depends heavily on user-specified parameters. This may be a problem in the practical tasks of data clustering and image segmentation. In order to remove the dependence of clustering results on user-specified parameters, we investigate the characteristics of existing clustering algorithms and present a parameter-free algorithm based on the DSets (dominant sets) and DBSCAN (Density-Based Spatial Clustering of Applications with Noise) algorithms. First, we apply histogram equalization to the pairwise similarity matrix of input data and make DSets clustering results independent of user-specified parameters. Then, we extend the clusters from DSets with DBSCAN, where the input parameters are determined based on the clusters from DSets automatically. By merging the merits of DSets and DBSCAN, our algorithm is able to generate the clusters of arbitrary shapes without any parameter input. In both the data clustering and image segmentation experiments, our parameter-free algorithm performs better than or comparably with other algorithms with careful parameter tuning. ? 1992-2012 IEEE.
Accession Number: 20162402480629
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Record 68 of
Title:Two-dimensional photon counting imaging detector based on PCB delay line anode
Author(s):Zhu, Bingli(1); Bai, Yonglin(1); Lei, Fanpu(1); Bai, Xiaohong(1); Wang, Bo(1); Qin, Junjun(1); Cao, Weiwei(1); Gou, Yongsheng(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10141 Issue: DOI: 10.1117/12.2255682 Published: 2016
Abstract:Delay line anode detector has high spatial resolution and high count rate. It has been an important technical means for single photon imaging from near earth space to deep space. A two dimensional delay line anode is designed using multilayer circuit board technology. A complete set of PCB delay line anode single photon detection system is established. The spatial resolution of the detector is theoretically analyzed. Moreover, the signal transmission characteristic of PCB delay line and the dark count rate of the detector are tested. Theoretical analysis and experimental results show that the detector spatial resolution is about 100um and the overall dark count rate is 4counts/cm2 at 2.3KV. ? 2016 SPIE.
Accession Number: 20165103156878
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Record 69 of
Title:Optimization design about gimbal structure of high-precision autonomous celestial navigation tracking mirror system
Author(s):Huang, Wei(1); Yang, Xiao-Xu(1); Han, Jun-Feng(1); Wei, Yu(1); Zhang, Jing(1); Xie, Mei-Lin(1); Yue, Peng(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9796 Issue: DOI: 10.1117/12.2229022 Published: 2016
Abstract:High precision tracking platform of celestial navigation with control mirror servo structure form, to solve the disadvantages of big volume and rotational inertia, slow response speed, and so on. It improved the stability and tracking accuracy of platform. Due to optical sensor and mirror are installed on the middle-gimbal, stiffness and resonant frequency requirement for high. Based on the application of finite element modality analysis theory, doing Research on dynamic characteristics of the middle-gimbal, and ANSYS was used for the finite element dynamic emulator analysis. According to the result of the computer to find out the weak links of the structure, and Put forward improvement suggestions and reanalysis. The lowest resonant frequency of optimization middle-gimbal avoid the bandwidth of the platform servo mechanism, and much higher than the disturbance frequency of carrier aircraft, and reduces mechanical resonance of the framework. Reaching provides a theoretical basis for the whole machine structure optimization design of high-precision of autonomous Celestial navigation tracking mirror system. ? 2016 SPIE.
Accession Number: 20163502747264
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Record 70 of
Title:A review of large aperture Schlieren photography technique
Author(s):Xu, Song-Bo(1); Xie, Yong-Jun(1); Chen, Lei(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9796 Issue: DOI: 10.1117/12.2230137 Published: 2016
Abstract:Schlieren photography is a visual process to display the flow of fluids of varying density. It is widely used in wind tunnel tests to photograph the flow of air around objects. To achieve schlieren images with high sensitivity and high resolution, and satisfy the requirements of the large-scale wind tunnel tests, it is urgent to develop schlieren photographers with large aperture primary mirrors. However, the application of large aperture primary mirrors may bring many challenges in the design of the schlieren system. First, the surface figure of large aperture primary mirrors is difficult to control so that the support structure may need more strategical design. Second, because the schlieren system works under some severe environments of the wind tunnel test including the air disturbance, wind-induced ground vibration and high ambient pressure, it has to withstand serious instability risks to ensure a good schlieren image quality. In this work, the current status of the development in the large aperture schlieren systems is reviewed. Several advanced methods, for example, active damping control technique, focal spot monitoring technique, 18-points whilffletree support technique, etc., are introduced to deal with the challenges of the large aperture schlieren system. This work aims at improving the technical development of large aperture schlieren photographer, which may contribute to the acquisition of the high sensitive and high resolution schlieren images and the improvement of the testing capability in wind tunnel experiments. ? 2016 SPIE.
Accession Number: 20163502747316
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Record 71 of
Title:Simulating the spatial resolution of the framing camera
Author(s):Bai, Xiaohong(1); Zhu, Bingli(1); Xu, Peng(1); Wang, Bo(1); Gou, Yongsheng(1); Qin, Junjun(1); Cao, Weiwei(1); Liu, Baiyu(1); Bai, Yonglin(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10141 Issue: DOI: 10.1117/12.2255140 Published: 2016
Abstract:The structural models of micro-channel plate (MCP) and fluorescent screen of the framing camera were established. By combining the finite element integration and Monte Carlo method, software Simion and Lorenz were respectively used to simulate the effects of different voltages loaded on the fluorescent screen, different closed distance between fluorescent screen and MCP, and electrode immersion depth at MCP output on the spatial resolution, in order to obtain an axisymmetric distribution curve. Results showed that the closed distance between MCP and fluorescent screen had the largest impact on the framing camera's spatial resolution. In addition, higher fluorescent screen voltage did not necessarily result in better spatial resolution, as it was influenced by the light-emitting mechanism of the fluorescent screen. At the framing camera's current closed distance of 0.8mm, a fluorescent screen voltage of 5000V could achieve the best spatial resolution. ? 2016 SPIE.
Accession Number: 20165103156876
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Record 72 of
Title:Thermal/structural/optical integrated design for optical sensor mounted on unmanned aerial vehicle
Author(s):Zhang, Gaopeng(1); Yang, Hongtao(1,2); Mei, Chao(1); Wu, Dengshan(1); Shi, Kui(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9796 Issue: DOI: 10.1117/12.2229726 Published: 2016
Abstract:With the rapid development of science and technology and the promotion of many local wars in the world, altitude optical sensor mounted on unmanned aerial vehicle is more widely applied in the airborne remote sensing, measurement and detection. In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 138.2 nm, which is under PV ≤1/4λ. The above study can be used as an important reference for other optical window designs. ? 2016 SPIE.
Accession Number: 20163502747300
