2019
2019
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Record 265 of
Title:Review of ground-based optical imaging techniques for dim GEO objects
Author(s):Luo, Xiu-Juan(1); Liu, Hui(1,2); Zhang, Yu(1); Chen, Ming-Lai(1,2); Lan, Fu-Yang(2)Source: Chinese Optics Volume: 12 Issue: 4 DOI: 10.3788/CO.20191204.0753 Published: August 1, 2019Abstract:Ground-based optical imaging is an important method for detecting and identifying space objects. The main reasons that the giant telescopes for astronomical observation established in the last decade cannot be used for high-resolution observation of GEO objects are analyzed. It is necessary to utilize unconventional imaging technology to solve image degradation due to GEO objects' small size, low-reflection and atmospheric turbulence. We have researched several new methods of unconventional optical imaging using laser illumination. The optical imaging techniques such as sparse aperture imaging, imaging correlography, Sheared-beam imaging and Fourier telescopy are analyzed and demonstrated. The advantages and limitations of each technique are discussed. The applications of high-resolution imaging for dim GEO objects are prospected. ? 2019, China Science Publishing & Media LTD. All right reserved.Accession Number: 20193907464306 -
Record 266 of
Title:On-orbit pointing adjusting mechanism of full-disc vector magnetograph (FMG)
Author(s):Sun, Zhenguo(1,2); Wang, Wei(1); Shi, Jinfeng(1); Xia, Siyu(1); Li, Xupeng(1,2); Song, Yang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504904 Published: 2019Abstract:This paper mainly introduces the motion analysis and the stress of some components of the full-disc vector magnetograph (FMG). As the connecting part of the FMG and the satellite platform, its main function is to adjust the optical axis of the FMG so that its imaging of the sun remains in the center of the CCD, thus achieving pitch and yaw of the optical axis. The maximum adjusting range is ±12′ and the regulation precision is ±5′′. The kinematic support is used to connect the optical box and the satellite platform. The two Monopods are respectively mounted on the two YZ planes of the optical cabin. The Bipod is mounted on the XZ plane of the optical capsule, which can adjust the pitch and yaw of the optical capsule. The movement of the Bipod is mainly powered by two motors. This paper simulates the force condition of the motor's screw sleeve to calculate the parameters of the motor. This article simulates the upward, downward, leftward and rightward movements of the pitch and yaw motions of the FMG's on-orbit pointing adjustment mechanism. Compared with the results of MATLAB theoretical calculations, the maximum error of the simulation results is 0.7969mm, and the minimum error is 0.0212mm, which basically accords with the ideal sports condition. ? 2019 SPIE.Accession Number: 20190506432483 -
Record 267 of
Title:Design of a visible-near-infrared hyperspectral microscopy optical systems
Author(s):Zhang, Zhoufeng(1,2,3); Hu, Bingliang(1); Yin, Qingye(2); Zhang, Zhaohui(1); Yu, Tao(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11023 Issue: DOI: 10.1117/12.2521813 Published: 2019Abstract:Hyperspectral imaging (HSI) acquires a three-dimensional dataset called hypercube, with two spatial dimensions and one spectral dimension. HSI is an emerging imaging modality for various medical applications, especially in disease diagnosis of early and biomedical research based on their unique spectral signatures. A visible-near-infrared HSI for microspectroscopy is designed, the measured spectrum is from 450 nm to 900 nm, which is sampled by 256 spectral channels. The spatial resolution is 1.25μm.The modulation transfer function (MTF) value of full spectrum and full field of view is close to the diffraction limit. At last, this microspecroscopy have been fabricated and preliminary tests have been implemented. The results indicated this visible-near-infrared hyperspectral microscopy optical systems have excellent optical performances. This hyperspectral microscopy will be well developed and used in the life sciences fields. ? 2019 SPIE.Accession Number: 20191506748671 -
Record 268 of
Title:Design and Electrical Analysis of Multi-Electrode Cylindrical Dielectric Barrier Discharge Plasma Reactor
Author(s):Niu, Guanghui(1); Guo, Guangmeng(2); Tang, Jie(3); Li, Yanping(4); Wang, Xu(5); Duan, Yixiang(5)Source: IEEE Transactions on Plasma Science Volume: 47 Issue: 1 DOI: 10.1109/TPS.2018.2883944 Published: January 2019Abstract:Dielectric barrier discharges (DBDs), due to its unique advantages such as simple design and low operation cost, have gained more and more attention all over the world. However, traditional plasma reactor can always have capacitive current with high peak values, which limits its further application in fields such as plasma catalytic reactions and surface treatment. In this proposed work, a new device named multielectrode cylindrical plasma reactor was presented, where the outer electrode was divided into several strips connected in parallel. The comparative electrical analysis was performed between the multielectrode plasma reactor and the traditional device. The experimental results showed that the multielectrode plasma reactor could give a much lower capacitive current peak value, namely, 5.49 mA compared with 16.26 mA of the traditional one, indicating that the new plasma reactor could decrease the capacitive current to a large extent as designed. In addition, due to the enhanced corona discharge, both the lifetime and peak values of the generated microdischarges were distributed more uniformly and concentrated in a small scale. In addition, the consumed energy by the designed multielectrode plasma reactor was decreased by 29.51% of the traditional plasma reactor, namely, 11.58 W compared with 16.43 W. The discharge mode was analyzed and determined to be mainly filament discharge with enhanced corona discharge at the electrode edges. In conclusion, the plasma reactor with proposed design can give a decreased capacitive current and also the consumed energy, which is helpful in broadening the application field of DBD in plasma catalysis fields. ? 2018 IEEE.Accession Number: 20185106275805 -
Record 269 of
Title:Optimized design of an emerging optical imager using compressive sensing
Author(s):Liu, Gang(1,2); Wen, Desheng(1); Song, Zongxi(1); Li, Zhixin(1,2); Zhang, Weikang(1,2); Wei, Xin(1,2)Source: Optics and Laser Technology Volume: 110 Issue: DOI: 10.1016/j.optlastec.2018.08.046 Published: February 2019Abstract:The emerging optical imager utilizes Fourier-domain interferometry and can reduce system weight, size and power by an order of magnitude compared to conventional optical telescopes at the same resolution. The compressive sensing theory demonstrates that incomplete and noisy measurements may actually suffice for accurate reconstruction of compressible or sparse signals. In this paper, we propose an optimized design of the emerging optical imager based on compressive sensing theory. It simplifies data acquisition structure and reduces data transmission burden. In addition, the system robustness is improved. ? 2018 Elsevier LtdAccession Number: 20183705805164 -
Record 270 of
Title:Supporting structure design between primary and secondary mirrors in a long focal length space optical remote sensor
Author(s):Hu, Bin(1,2); Wu, Mengyuan(1); Ye, Jing(1,2); Li, Yan(1); Li, Xuyang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504859 Published: 2019Abstract:To ensure the dimensional stability of the opto-mechanical structure of the space optical remote sensor is an important prerequisite for the acquisition of high quality images. The change of the relative position between the primary and secondary mirrors has a great influence on the imaging quality of the long focal length optical remote sensor. Several common forms of supporting structure between the primary and secondary mirrors and the secondary mirror support of lightweight, high stiffness have been analyzed. This paper has designed a baffle tube between primary and secondary mirrors of high modulus carbon fiber M55J/cyanate ester material, carbon fiber composite main body with titanium alloy inserts integral the secondary mirror supporting structure. Through static and dynamic analysis, it is proved that the designed optical remote sensor has good structural stability and dynamic characteristics, and meets the requirements of engineering application. ? 2019 SPIE.Accession Number: 20190506432480 -
Record 271 of
Title:Dictionary learning based target detection for hyperspectral image
Author(s):Zhang, Xiaorong(1,2,3); Hu, Bingliang(1); Pan, Zhibin(2); X., ZhengSource: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11023 Issue: DOI: 10.1117/12.2519943 Published: 2019Abstract:Target detection of hyperspectral image has always been a hot research topic, especially due to its important applications in military and civilian remote sensing. This paper employs the idea of classification and proposes a novel detection framework which incorporates dictionary learning and discriminative information. Due to the fact that target pixels lie in different subspace with background pixels, a novel detection model is proposed. In addition, a linear kernel is applied to project the image data into high-dimensional space, separating the target pixels and background pixels. Synthetic image and popular real hyperspectral image are used to evaluate our algorithm. Experimental results indicate that our proposed detector outperforms the traditional detection methods. ? 2019 SPIE.Accession Number: 20191506748653 -
Record 272 of
Title:Review on the research of space-based direct imaging technologies for exoplanets detection
Author(s):Hu, Bin(1,2); Li, Chuang(1); Li, Xuyang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2542957 Published: 2019Abstract:The detection of exoplanets is a hot topic in international astronomy nowadays. The methods of exoplanets detection are mainly divided into indirect detection and direct imaging. Direct imaging of exoplanets is being pursued by a number of research groups around the world. In this paper, the research status of space-based direct imaging technologies for exoplanets detection is reviewed, and the advantages and disadvantages of related technologies are analyzed and summarized. The most advantageous and promising space-based nulling interferometry technologies are described in detail, including some laboratory verification studies based on ground-based astronomical telescopes. With the continuous development of spacecraft micro-Newton propulsion and high-precision positioning control, ultra-high-precision laser measurement, adaptive optics, integrated optics, etc., space-based direct imaging technologies for exoplanets detection will continue to make breakthroughs. ? 2019 SPIE.Accession Number: 20200408063344 -
Record 273 of
Title:A focusing mechanism based on flexible hinges for space telescope
Author(s):Ma, Xiaozhe(1,2); Li, Chuang(1); Cheng, Penghui(1,2); Hu, Bin(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11063 Issue: DOI: 10.1117/12.2539681 Published: 2019Abstract:In this paper, a new type of focusing mechanism for space telescope is designed to compensate defocusing caused by alteration of space condition in orbit. The focusing mechanism is driven by a stepping motor and a worm gear reducer, transmitted by a ball screw and output by a flexible hinge. It has advantages of low mass, small overall size and especially high accuracy that is better than 1 micrometer. As one of main parts of focusing mechanism, the flexible hinge is mounted in the focusing shaft and connected to the nuts of ball screw kinematic pair which has mechanical end stops. The focusing shaft is guided by two couples of thin film boards to ensure the precise displacement along optical axis direction. The secondary mirror frame is connected to the shaft to complete focusing. Firstly, the focusing mechanism is designed, and the design scheme is illustrated in this paper. Then a modal analysis with finite element method for the mechanism is completed. The results show that the dynamic stiffness is high enough and meets the requirement. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20195207919108 -
Record 274 of
Title:Performance analysis of different pixel-wise processing methods for depth imaging with single photon detection data
Author(s):Kang, Yan(1,2); Li, Lifei(1); Li, Dongjian(1); Liu, Dawei(1,2); Zhang, Tongyi(1,2); Zhao, Wei(1,2)Source: Journal of Modern Optics Volume: 66 Issue: 9 DOI: 10.1080/09500340.2019.1596322 Published: May 21, 2019Abstract:We establish a long-range single photon counting three-dimensional (3D) imaging system based on cage optical structure. Five different pixel-wise processing methods for time-of-flight (TOF) photon counting data are compared with data collected by our 3D imaging system for ranges 40–700 m and a suitable representation model for photon counting data is proposed for pixel-wise processing. Experimental results show that these methods exploit the instrumental response function (IRF), yielding a high-quality 3D image. When the signal photon counts are greater than 13 per pixel, the resulting mean absolute error (MAE) values of the IRF-based methods are better than results from the non-IRF-based methods. Regarding IRF-based methods, the union of subspace (UOS) model-based approach and cross correlation are more suitable than the Markov chain Monte Carlo (MCMC) method in the condition of a small number of return signal photons. These results offer valuable information to promote the implementation of photon counting 3D imaging in real applications. ? 2019, ? 2019 Informa UK Limited, trading as Taylor & Francis Group.Accession Number: 20191406717352 -
Record 275 of
Title:Query-aware sparse coding for web multi-video summarization
Author(s):Ji, Zhong(1); Ma, Yaru(1); Pang, Yanwei(1); Li, Xuelong(2)Source: Information Sciences Volume: 478 Issue: DOI: 10.1016/j.ins.2018.09.050 Published: April 2019Abstract:Given the explosive growth of online videos, it is becoming increasingly important to relieve the tedious work of browsing and managing the video content of interest. Video summarization aims at providing such a technique by transforming one or multiple videos into a compact one. However, conventional multi-video summarization methods often fail to produce satisfying results as they ignore the users’ search intents. To this end, this paper proposes a novel query-aware approach by formulating the multi-video summarization in a sparse coding framework, where the web images searched by a query are taken as the important preference information to reveal the query intent. To provide a user-friendly summarization, this paper also develops an event-keyframe presentation structure to present keyframes in groups of specific events related to the query by using an unsupervised multi-graph fusion method. Moreover, we release a new public dataset named MVS1K, which contains about 1000 videos from 10 queries and their video tags, manual annotations, and associated web images. Extensive experiments on the MVS1K and TVSum datasets demonstrate that our approaches produce competitively objective and subjective results. ? 2018Accession Number: 20184706111952 -
Record 276 of
Title:Compact Space Optical System Design with Large Relative Aperture and Field of View
Author(s):Ren, Zhiguang(1,2); Li, Xuyang(1); Ni, Dongwei(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 39 Issue: 9 DOI: 10.3788/AOS201939.0922001 Published: September 10, 2019Abstract:An imaging optical system with large relative aperture and field of view was designed based on a modified Mangin mirror. The aberrations of the modified Mangin mirror are analyzed and a design method is proposed for it. The optical system adopts a combination of an improved Mangin mirror and a catadioptric optical system. The relative aperture is 1/1.8, field of view is 4°× 4°, working band is 450-850 nm, and focal length is 380 mm. The imaging detector is a CMOS detector with pixel of 2 μm×2 μm. The modulation transfer function value is close to the diffraction limit and greater than 0.5 at a Nyquist frequency of 250 lp/mm. The secondary mirror of the system is designed based on a Mangin mirror and an achromatic lens. Based on the spherical aberration and sine aberration obtained from the preliminary optimization analysis of the initial system structure, the focal power of the achromatic Mangin mirror is solved by the PW method. Based on achromatic conditions and residual chromatic aberration of the system, the focal powers of three surfaces of the achromatic Mangin mirror are solved and the radii of the surfaces can be calculated. The system has small monochromatic and chromatic aberrations and good imaging quality. ? 2019, Chinese Lasers Press. All right reserved.Accession Number: 20194307574881