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Simulation and analysis of co-phasing errors of the segmented primary mirror tiled by hexagonal segments in LOT

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Research in Astronomy and Astrophysics 2021年第10期21卷 37-45页

作者： Shi-Dong Shen xiang-qun {2. yong zhang national astronomical {2./nanjing institute of astronomical optics&technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of astronomical optics&{2. Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of the Chinese academy of sciences Beijing 100049China

In this paper,co-phasing errors of a segmented primary mirror tiled by hexagonal segments are successfully calculated for the 12.meter Large aperture Optical/infrared Telescope(LOT).Co-phasing errors including out-of-plane errors are simulated separately and comprehensively based on several software simulation *** simulation results show that the Strehl Ratio(SR)of LOT is larger than 0.8 when the RMS value of tip-tilt obeying a normal distribution is less than 0.018 arcsec,and the SR of LOT is larger than 0.8 when the RMS value of piston obeying a normal distribution is less than 40 ***,simulation results of Zemax show that the SR of LOT is larger than 0.8 when the RMS value of tip-tilt obeying a normal distribution is less than 0.02.arcsec,and the SR of LOT is larger than 0.8 when the RMS value of piston obeying a normal distribution is less than 40 *** simulation results successfully lay a solid foundation for LOT(especially the segmented primary mirror with active optics).

关键词： methods:analytical techniques:miscellaneous telescopes

Automatic generation of optical initial configuration based on Delano diagram

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Research in Astronomy and Astrophysics 2016年第1期16卷 59-66页

作者： Kai-Yuan zhang xiang-Yan Yuan xiang-qun cui national astronomical {2./nanjing institute of astronomical optics & technology Nanjing 210042 China Key Laboratory of astronomical optics & {2. Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing 210042 China University of Chinese academy of sciences Beijing 100049 China

This paper presents a method to automatically initialize an optical system based on the Delano diagram. The process to generate the optical initial configuration is constrained by the control points, which are deduced from parameters related to basic design requirements. We present the theory and method to generate the optical initial configuration automatically when the basic design requirements are known. Two optical systems are taken as examples to demonstrate the proposed method.

关键词： telescopes -- methods: analytical

Preliminary numerical simulation of mirror seeing for the Chinese Future Giant Telescope

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Research in Astronomy and Astrophysics 2016年第6期16卷 123-128页

作者： En-Peng zhang xiang-{2. cui Guo-Ping Li yong zhang Jian-Rong Shi yong-Heng Zhao national astronomical {2. Chinese Academy of Sciences Key Laboratory of Optical Astronomy Chinese Academy of Sciences nanjing institute of {2. optics and technology National Astronomical ObservatoriesChinese Academy of Sciences

Mirror seeing will be one of the key factors influencing image quality of an extremely large ground-based optical telescope （ELT）. Computational fluid dynamics （CFD） can be used to estimate the mirror seeing and the effects of ventilation. In this paper, we present a simplified approach to simulation of mirror seeing for the Chinese Future Giant Telescope （CFGT, 30 m in diameter） with the CFD software ANSYS Icepak. We get the FWHM of the image and the distribution of refractive index structure function （CN2. above the mirror. We demonstrate that thermal control and ventilation are effective ways to improve the image quality. Our simulation results agree with those of other authors for the ELT. To reduce the mirror seeing to a level of 0.5＂, the suggested temperature excess of the primary mirror above the ambient air for thermal control of the CFGT is 0 - 2.K according to the present results of weakly forced convection. The limitations of the method are also discussed.

关键词： astronomical instrumentation -- methods numerical -- telescopes

Estimating the mirror seeing for a large optical telescope with a numerical method

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Research in Astronomy and Astrophysics 2018年第5期18卷 131-136页

It is widely accepted that mirror seeing is caused by turbulent fluctuations in the index of air refraction in the vicinity of a telescope mirror. Computational Fluid Dynamics（CFD） is a useful tool to evaluate the effects of mirror seeing. In this paper, we present a numerical method to estimate the mirror seeing for a large optical telescope（～ 4 m） in cases of natural convection with the ANSYS ICEPAK software. We get the FWHM of the image for different inclination angles（i） of the mirror and different temperature differences（△T） between the mirror and ambient air. Our results show that the mirror seeing depends very weakly on i, which agrees with observational data from the Canada-FranceHawaii Telescope. The numerical model can be used to estimate mirror seeing in the case of natural convection although with some limitations. We can determine △T for thermal control of the primary mirror according to the simulation, empirical data and site seeing.

关键词： astronomical instrumentation - methods numerical- telescopes

Focal surface attitude detection for LAMOST

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Research in Astronomy and Astrophysics 2020年第11期20卷 263-272页

作者： Tian-Zhu Hu yong zhang {2.-qun cui Ye-Ping Li Xiu-Shan Pan Ying Fu national astronomical {2./nanjing institute of astronomical optics&technology Chinese Academy of ScienceNanjing 210042China CAS Key Laboratory of astronomical optics&{2. Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of Chinese academy of sciences Beijing 100049China

With telescope apertures becoming larger and larger,the deployment of large-field telescopes is becoming increasingly ***,optical path calibration is necessary to ensure the image quality of large-field and large-diameter *** particular,focal plane attitude calibration is an essential optical path calibration technique that has a direct impact on image *** this paper,a focal plane attitude detection method using eight acquisition cameras is proposed based on the calibration requirements of the wide-field telescope,LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope).Comparison of simulation and experimental results shows that the detection accuracy of the proposed method can reach 30 *** additional testing and verification,this method could be used to facilitate regular focal plane attitude calibration for LAMOST as well as other large-field telescopes.

关键词： methods data analysis techniques high angular resolution techniques image processing

Number and Distribution of Fiducial Fibers in a Spectroscopic Survey Telescope

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Research in Astronomy and Astrophysics 2022年第2期22卷 108-117页

作者： Shi-Peng Duan Zeng-xiang Zhou Jia-Le Zuo Meng-Tao Li Zhi-Gang Liu Hong-Zhuan Hu Jian-Ping Wang xiang-{2. cui yong zhang Hao-Tong zhang Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China national astronomical {2./nanjing institute of astronomical optics&technology Chinese Academy of ScienceNanjing 210042China CAS Key Laboratory of astronomical optics&{2. Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China national astronomical {2. Chinese Academy of SciencesBeijing 100012China

To date,the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)has been in operation for 12.*** improve the telescope's astronomical observation accuracy,the original open-loop fiber positioning system of LAMOST is in urgent need of *** upgrade plan is to install several fiber view cameras(FVCs)around primary mirror B to build a closed-loop feedback control *** FVCs are 2. m from the focal *** reduce a series of errors when the cameras detect the positions of the optical fibers,we designed fiducial fibers on the focal surface to be fiducial points for the *** the number of fiducial fibers can improve the detection accuracy of the FVC system,but it will also certainly reduce the number of fiber positioners that can be used for ***,the focus of this paper is how to achieve the quantity and distribution that meet the requirements of system *** this paper,we introduce the necessity of using fiducial fibers,propose a method for selecting their number and present several methods for assessing the uniformity of their ***,we implement particle swarm optimization to find the best distribution of fiducial fibers.

关键词： instrumentation detectors-techniques image processing-methods data analysis-telescopes

Defocus spot detection of astronomical optical system

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Research in Astronomy and Astrophysics 2020年第3期20卷 162-169页

作者： Tian-Zhu Hu yong zhang {2.-qun cui Ye-Ping Li Hua Bai Xiu-Shan Pan national astronomical {2./nanjing institute of astronomical optics&Tech no logy.Chinese academy of Science Nanjing 210042China Key Laboratory of astronomical optics&{2. Nanjing Institute of Astronomical Optics&TechnologyChinese Academy of SciencesNanjing 210042China University of the Chinese academy of sciences Beijing 100049China

Defocusing spot size detection is especially essential for aberration analysis and correction of optical systems. In the case of far defocusing, the celestial forms a pupil image on the detector, and the size of the image is linearly changed with the defocusing distance, and can be used to correct the optical system and analyze the image quality. Based on the focal plane attitude detection of Large Sky Area MultiObject Fiber Spectroscopy Telescope(LAMOST), this paper uses a variety of methods to detect the size of the defocusing spot of LAMOST telescope. For the particularity of the spot, the average value spacing algorithm, the peak value spacing algorithm, the ellipse fitting algorithm, and the multi-peak Gaussian fitting algorithm are used to detect the spot size. This paper will introduce these four methods, in which the average value spacing algorithm is proposed by the author of this paper. The advantages and disadvantages of the four methods are compared. The experimental results show that the average value spacing algorithm can achieve better accuracy of spot size detection in the four algorithms.

关键词： methods data analysis-techniques image processing-telescopes

Testing and data reduction of the Chinese Small Telescope Array(CSTAR) for Dome A,Antarctica

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Research in Astronomy and Astrophysics 2010年第3期10卷 279-290页

作者： Xu Zhou Zhen-Yu Wu Zhao-Ji Jiang xiang-qun {2. Long-Long Feng Xue-Fei Gong Jing-Yao Hu Qi-Sheng Li Gen-Rong Liu Jun Ma Jia-Li Wang Li-Fan Wang Jiang-Hua Wu Li-Rong Xia Jun Yan xiang-Yan Yuag Feng-xiang Zhai Ru zhang Zhen-Xi Zhu national astronomical {2. Chinese Academy of Sciences Beijing 100012 China nanjing institute of {2. optics ＆ technology National Astronomical Observatories Chinese Academy of Sciences Nanjing 210042 China Purple MountainObservatory Chinese Academy of Sciences Nanjing 210008 China Chinese Center for Antarctic Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

The Chinese Small Telescope Array （CSTAR） is the first Chinese astronomical instrument on the Antarctic ice cap. The low temperature and low pressure testing of the data acquisition system was carried out in a laboratory refrigerator and on the 4500 m Pamirs high plateau, respectively. The results from the final four nights of test observations demonstrated that CSTAR was ready for operation at Dome A, Antarctica. In this paper, we present a description of CSTAR and the performance derived from the test observations.

关键词： instrumentation: detectors -- techniques: photometric -- stars: variables

A fiber bundle structure with uniform transmission characteristics for high-density astronomical optical cables

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Research in Astronomy and Astrophysics 2019年第8期19卷 131-142页

作者： Qi Yan Tao Geng Hang Jiang Chuang Zhao Ying-Hua zhang An-Zhi Wang Jia-Bin Wang Xi-Ren Jin Xu-Dong Chen Chun-Lian Lu Liang Wang Zhi-Xin Huang Jing-Dong Zhuang Song Wang Wei-Min Sun xiang-{2. cui Key Lab of In-fiber Integrated optics Ministry Education of ChinaHarbin Engineering UniversityHarbin150001China Yangtze Optical Fibre and Cable Joint Stock Limited Company Wuhan430073China nanjing institute of {2. optics and technology National Astronomical ObservatoriesChinese Academy ofSciencesNanjing210042China

Transmission efficiency(TE) and focal ratio degradation(FRD) are two important parameters for evaluating the quality of an optical fiber system used for astronomy. Compared to TE, the focal ratio is more easily influenced by external factors, such as bending or stress. Optical cables are widely implemented for multi-object telescopes and integral field units(IFUs). The design and fabrication process of traditional optical cables seldom considers the requirements of astronomical applications. In this paper, we describe a fiber bundle structure as the basic unit for miniaturized high-density FASOT-IFU optical cables,instead of the micro-tube structure in stranded cables. Seven fibers with hexagonal arrangement were accurately positioned by ultraviolet(UV)-curing acrylate to form the bundle. The coating diameter of a fiber is0.12. mm, and the outer diameter of the bundle is 0.58 mm. Compared with the 0.8 mm micro-tube structure of a traditional stranded cable, the outer diameter of the fiber bundle was reduced by 2..5%. Fiber paste was filled into the bundle to reduce stress between the fibers. We tested the output focal ratio(OFR) in95% of the encircled energy(EE95) of the fibers in the bundle under different conditions. With the incident focal ratio F/8, the maximum difference of OFR is 0.6. In particular, when the incident focal ratio is F/5,the maximum difference of OFR is only 0.1. The jacket formed by the UV-curing acrylate can withstand a certain stress of less than 1.38 N mm-1. The fiber bundle can maintain uniform emitting characteristics with a bending radius of 7.5 cm and with tension less than 6 N. The test results show that the structure of the fiber bundle can be used as a basic unit for miniaturized high-density astronomical optical cables.

关键词： instrumentation:spectrographs techniques:imaging spectroscopy techniques:spectroscopic methods:miscellaneous