2021
2021
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Record 301 of
Title:Optical path pointing error and coaxiality analysis of APT system of space laser communication terminal
Author(s):Furui, Zhang(1); Ping, Ruan(2); Junfeng, Han(2)Source: Optica Applicata Volume: 51 Issue: 2 DOI: 10.37190/oa210205 Published: 2021Abstract:Precision beam pointing is the key indicator for APT (acquisition, pointing and tracking) system in space laser communication. The laser travels inside the optical system and the pointing vector will be affected by an assembly error of the axis and reflectors. In this paper, the model of the optical path pointing error and coaxiality error induced by the assembly error are established; the error distribution is given and a quantitative analysis is performed. The results show that the magnitude of pointing error is affected by the axis assembling error greatly but its distribution is susceptible to the reflector assembly error. Finally, the correction of coaxiality is performed and tested. The experimental results show that the coaxiality error can be greatly improved and the mean value of the coaxiality error of a beacon path and a signal path are 14 and 9.6 μrad, respectively, which meets the requirements. This work can provide guidance for design and assembly of the APT and contribute to the improvement of its pointing performance. ? 2021 Wroc??aw University of Science and Technology. All rights reserved.Accession Number: 20213110715981 -
Record 302 of
Title:Adaptive Weighted Exposure Algorithm Based on Region Luminance Detection
Author(s):Yang, Lei(1,2); Zhang, Derui(1,2); Cao, Jianzhong(1,2); Zhang, Hui(1,2); Wang, Hua(1,2); Bian, He(2); Wang, Huawei(2)Source: 2021 IEEE 3rd International Conference on Communications, Information System and Computer Engineering, CISCE 2021 Volume: Issue: DOI: 10.1109/CISCE52179.2021.9445988 Published: May 14, 2021Abstract:When the traditional global auto-exposure algorithm is applied to high contrast special scenes such as dark background and bright target, there is often over-exposure of the target, which leads to the loss of the key information of the subject concerned. To solve this problem, an adaptive weight exposure method based on regional brightness detection is proposed. Firstly, the whole imaging field of view is divided into several regions, and then the position of the target in the field of view is identified by independent judgment. Finally, the automatic exposure control of gray statistics is carried out according to the preset region weight. The experimental results show that the proposed method can effectively improve the image quality of the bright target or dark target in the dark background, avoid the phenomenon of the target too bright or too dark, and better capture the texture features of the target. ? 2021 IEEE.Accession Number: 20213110705823 -
Record 303 of
Title:Large-range piston error detection technology based on dispersed fringe sensor
Author(s):Wang, Pengfei(1,2); Zhao, Hui(1); Xie, Xiaopeng(1); Zhang, Yating(1,2); Li, Chuang(1); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12070 Issue: DOI: 10.1117/12.2604553 Published: 2021Abstract:Synthetic aperture is the mainstream structure of current astronomical telescopes. However, after the synthetic aperture telescope is deployed in orbit, there will remain tilt and piston error between adjacent segments, which will sharply deteriorate the imaging quality of the optical system. The traditional piston error detection method based on dispersed fringe sensor has the question that it is difficult to detect the piston error within one wavelength, and the detection accuracy is restricted by the detection range. The method in this paper constructs multiple monochromatic light channels by opening windows in different areas on the dispersed fringe pattern, calculating and obtaining the feature value in each window to form a feature vector. Then, the convolutional neural network is introduced to distinguish the feature vector to detect piston error. Among them, the training set construction method adopted in this paper only needs raw data in one wavelength to construct a training set covering the entire detection range. Through simulation, the method proposed in this paper achieves the detection range of [-208λ, 208λ] (λ=720nm), and regardless of the presence of noise, the root mean square value of the detection error does not exceed 17.7nm (0.027λmin, λmin=660nm). ? 2021 SPIEAccession Number: 20220811682283 -
Record 304 of
Title:Mass-property Identification System for Three-axis Air Bearing Table Based on Simulated annealing Algorithm and Fading Memory Filter
Author(s):Wang, Zhenyu(1); Li, Zening(2); Xu, Xu(2); Li, Zhiguo(1); Ma, Guangcheng(2); Xia, Hongwei(2)Source: Chinese Control Conference, CCC Volume: 2021-July Issue: DOI: 10.23919/CCC52363.2021.9550654 Published: July 26, 2021Abstract:The mass property of the three-axis air bearing table is unknown when simulating the attitude and orbital motion of a satellite. This paper builds a mathematical model for the identification of the quality characteristics of the three-axis air bearing table. An identification method for the quality characteristics of a three-axis air bearing table based on the simulated annealing algorithm (SA) is proposed. To improve the identification accuracy, a method for identifying the quality characteristics of a three-axis air bearing table based on the fading memory filter (FM) is proposed. The mass-property identification system uses flywheels as the excitation source of the three-axis air bearing and uses the inertial measurement unit (IMU) to measure the angular velocity. The results show that the moment of inertia identification error of the SA algorithm is about 3.48%, and it is capable of getting away from local optimum. The moment of inertia identification error based on the FM filter is less than 2% with faster convergence speed and higher identification accuracy. ? 2021 Technical Committee on Control Theory, Chinese Association of Automation.Accession Number: 20214311046490 -
Record 305 of
Title:Novel Structure Design of Circle Support Component for a Primary Reflective Mirror with Large Diameter
Author(s):Song, Yang(1); Ye, Jing(1,2); Shen, Zhong(1); Ma, Tengfei(1); Hu, Yongming(1); Wang, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12070 Issue: DOI: 10.1117/12.2604296 Published: 2021Abstract:With the rapid progress of technology and manufacture, the number of telescopes in space is mounting dramatically. Considering launch cost, more and more engineers nowadays pursue lightweight and compact design of telescope in space. Traditional design scheme usually has a support plate for primary reflective mirror. It will take some space for other parts. The paper, taking a primary reflective mirror with 600mm in diameter as an example, put forward a novel design of circle support component instead of traditional support plate. It utilized a special structural layout to save more space. The paper specified this design scheme and made comparison between these two design schemes. The paper also gave the assembling method of the primary reflective mirror and circle support component, which would verify its feasibility in engineering practice in a virtual way. The novel structure design in this paper will give some guidance to engineers and designers, who are devoting themselves to designing space telescopes. ? 2021 SPIEAccession Number: 20220811682269 -
Record 306 of
Title:Design of special cylinder support for reflective mirror in space optical instrument for laser communication
Author(s):Song, Yang(1); Chai, Wenyi(1); Shen, Zhong(1); Ye, Jing(1,2); Ma, Tengfei(1); Hu, Yongming(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12057 Issue: DOI: 10.1117/12.2604298 Published: 2021Abstract:The number of space optical instruments is growing with a quick pace. Reflective mirror is always a significant part in a space optical system, especially in the laser communication system. Support is used to connect reflective mirror to other structure. The paper focused on designing a cylinder support. Considering thermal condition in space, the paper gave a special design of support with some soft links. The paper made a comparison between traditional design scheme of cylinder support and new design scheme of special cylinder support. From the comparison, it could be concluded that new design scheme had better performance in the thermal condition. Later, modal analysis and some vibration analyses were done to verify the reliability and feasibility of the new design. The result showed the design scheme was good. ? 2021 COPYRIGHT SPIE.Accession Number: 20215211375318 -
Record 307 of
Title:Determination of the photoemission position in single-photon ionization with attosecond streaking spectroscopy
Author(s):Wang, Feng(1); Liao, Qing(1); Liu, Kai(1); Qin, Meiyan(1); Zhang, Xiaofan(1); Zhang, Qingbin(2); Cao, Wei(2); Pi, Liang-Wen(3); Zhou, Yueming(2); Lu, Peixiang(4)Source: Physical Review A Volume: 103 Issue: 1 DOI: 10.1103/PhysRevA.103.013115 Published: January 2021Abstract:Attosecond metrology can directly measure attosecond emission time of photoexcited electrons from matter, providing unprecedented understanding of transition processes of electrons from bound to continuum states. However, some fundamental details of the electron dynamics in the entire emission process upon photoexcitation still remain debatable or unknown. The photoemission time delays deduced from attosecond streaking spectroscopy originate from photoelectron propagation in the coupled Coulomb-laser fields, encoding the spatial and spectral information of electrons upon photoexcitation. Here we demonstrate that attosecond photoemission delays can be used to image picometer-resolved photoemission position via a classical model. The electronic dynamics in the laser-assisted single-photon ionization process is fully captured by a quantum path-integral model. We trace the imaged photoemission position to the average position of spatially coherent superposition of electron waves upon photoexcitation and, in particular, predict emission position coinciding with the orbital radius of the ground state of hydrogen-like atoms, in contrast with previous predictions. ? 2021 American Physical Society.Accession Number: 20210609889126 -
Record 308 of
Title:Design of Optical System for Broadband and Integrated AOTF Imaging Spectrometer
Author(s):Chang, Lingying(1); Zhang, Qiang(1); Qiu, Yuehong(2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 41 Issue: 7 DOI: 10.3788/AOS202141.0722002 Published: April 10, 2021Abstract:Acousto-optic tunable filter (AOTF) imaging spectrometer can acquire image, spectrum and polarization information simultaneously. It has been successfully applied to the aerospace, agriculture, forestry, medicine, food safety, and other fields, thus having good development prospects. Optical system is one of the key parts in an AOTF imaging spectrometer to obtain information. Therefore, the optical systems of common AOTF imaging spectrometers are studied in this paper, and the working principle of AOTF and the general design scheme of the spectrometers are introduced. Furthermore, the optical design parameters of the whole system, such as the front, collimating and imaging sub-systems are calculated, and the common-aperture optical system is simulated. The front optical system has an off-axis three-mirror structure based on free-form surface, which matches with the aperture stop of the collimating system, and the collimating and imaging systems are off-axis three-mirror systems with front offset of the aperture stop. The simulation results show that the system has an MTF values close to the diffraction limit and greater than 0.57 at the bands of 0.41.0 μm, 1.03.0 μm, and 3.05.0 μm, a distortion less than 5%, and good imaging quality, in the case of the working band of 0.45.0 μm, F number 5, field of view angle of 5.3°. ? 2021, Chinese Lasers Press. All right reserved.Accession Number: 20212110404350 -
Record 309 of
Title:Extraordinary Fast Forward and Backward Light in Transparent Non-Hermitian Systems
Author(s):Zhang, Lingxuan(1); Ying, Lei(2); Ge, Li(3,4); Zhao, Wei(1); Zhang, Wenfu(1)Source: Laser and Photonics Reviews Volume: 15 Issue: 5 DOI: 10.1002/lpor.202000204 Published: May 2021Abstract:The phenomenon of fast forward and backward light pulse propagation in effectively transparent non-Hermitian photonic systems is reported. Specifically, the propagation eigenmodes are analyzed in several parity-time-symmetric coupled waveguides. In contrast to a previous finding that showed slow light due to an exceptional point in such systems, a critical point in its close proximity that displays a diverging dispersion is identified. Superluminal light pulse propagation in the forward and backward directions is then found and observed numerically on the two sides of the critical point, respectively. This abnormal phenomenon can be understood by a conservation relation of group velocities, which can be extended to other transparent non-Hermitian photonic systems with different symmetries. More importantly, the abrupt transition across the critical point between the fast forward and backward light can be tuned, indicating the possibility of detecting atom-scale movement of the waveguides with little time delay. In addition, bandwidth broadening and a passive superluminal propagation configuration are discussed. ? 2021 Wiley-VCH GmbHAccession Number: 20211210107681 -
Record 310 of
Title:Optimal design of aspheric Offner compensator based on computer aided program
Author(s):Meng, Wen(1,2); Ma, Zhen(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12069 Issue: DOI: 10.1117/12.2606582 Published: 2021Abstract:This paper presents an automatic optimization method in ZEMAX sequential mode. The user-defined evaluation function and optimization program are written in macro language, which is used to design the Offner null compensation optical path system. The system is designed with a 1m aperture parabolic lens as an example, of two-piece Offner compensation mirror and the optimal parameters of Offner compensator are obtained through optimization. The compensation residual PV value is better than λ/10 and the RMS value is better thanλ/50. This method is a promising attempt of automatic design of compensator, which can design multiple groups of structures on the basis of improving design efficiency, and make the optimal structure which is more closer to actual demand. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20220211444597 -
Record 311 of
Title:Investigation of wheel polishing technology based on industrial robot
Author(s):Yao, Yongsheng(1,2); Li, Qixin(1,2); Shen, Le(1); DIng, Jiaoteng(1,2); Ma, Zhen(1); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12071 Issue: DOI: 10.1117/12.2605412 Published: 2021Abstract:In this paper, industrial robot is used as motion carrier and self-developed flexible wheel tool is used as polishing tool to realize low-cost, high-efficiency, and high-precision optical processing. Firstly, the mapping formula between the workpiece coordinates and the road point coordinates is deduced, and the position and posture data required for robot programming are obtained. Secondly, a new type of wheel polishing tool is designed, which controls the polishing pressure through a pneumatic floating structure to ensure the stability of the removal function. Finally, an off-axis paraboloid of φ345mm was processed using this technology. After three times of processing for 10 hours, the surface error converged from PV-2.111λ, RMS-0.249λ to PV-0.119λ, RMS-0.01λ. PV and RMS converged by 94% and 96%, respectively. This proves that the technology has the advantages of high efficiency and high precision, and is expected to be widely used in the field of precision optical processing. ? COPYRIGHT SPIE.Accession Number: 20220811674420 -
Record 312 of
Title:High-power ultraviolet laser at 343 nm based on femtosecond fiber laser system
Author(s):Wu, Tianhao(1,2); Li, Feng(1); Yang, Xiaojun(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12060 Issue: DOI: 10.1117/12.2606840 Published: 2021Abstract:Femtosecond laser has the characteristics of short pulse width and high peak power and is widely used in laser micromachiningoptical communication, medical applications and other fields. Compared with infrared lasers, ultraviolet lasers have shorter wavelength and higher single-photon energy, which makes the processing heat affected area smaller and can perform precise processing on special materials. With the advancement of science and technology, people are demanding higher precision in laser processing, then ultrashort pulse lasers in the ultraviolet spectrum have gradually came into people's sight. At present, there have been many reports on femtosecond solid-state ultraviolet lasers domestic and overseas. However, solid-state lasers are bulky and difficult to dissipate heat. In contrast, the fiber femtosecond laser has a stable and compact structure and is more suitable for industrial processing. However, it is understood that there are very few domestic studies on femtosecond fiber lasers in the ultraviolet band. In recent years, fiber laser technology has been greatly developed. Femtosecond fiber lasers have good beam quality and high laser directivity, besides it can provide high-power, high-repetition output in the near-infrared spectrum. In this experiment, we propose an ultraviolet femtosecond laser system based on β-BaB2O4 crystal. The fundamental frequency laser passes through two BBO crystals to generate second harmonic generation and third harmonic generation. At the same time, we adjust the angle at which each beam of laser passes through each crystal to meet the conditions of phase matching and obtain the maximum conversion efficiency. It's worth mentioning that the system has a compact structure, low cost, and high conversion efficiency. Besides, it has broad application prospects. ? 2021 SPIE.Accession Number: 20220211446982