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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 Observatories/Nanjing Institute of Astronomical Optics & Technology Nanjing 210042 China Key Laboratory of Astronomical Optics & Technology 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

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 cui Yong Zhang National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology 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

Correction and simulation of the intensity compensation algorithm used in curvature wavefront sensing

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Research in Astronomy and Astrophysics 2015年第5期15卷 764-772页

作者： Zhi-Xu Wu Hua Bai xiang-qun cui National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Key Laboratory of Astronomical Optics & Technology Nanjing Institute of Astronomical Optics&Technology Chinese Academy of Sciences University of Chinese Academy of Sciences

The wavefront measuring range and recovery precision of a curvature sensor can be improved by an intensity compensation algorithm. However, in a focal system with a fast f-number, especially a telescope with a large field of view, the accuracy of this algorithm cannot meet the requirements. A theoretical analysis of the corrected intensity compensation algorithm in a focal system with a fast f-number is first introduced and afterwards the mathematical equations used in this algorithm are expressed. The corrected result is then verified through simulation. The method used by such a simulation can be described as follows. First, the curvature signal from a focal system with a fast f-number is simulated by Monte Carlo ray tracing; then the wavefront result is calculated by the inner loop of the FFT wavefront recovery algorithm and the outer loop of the intensity compensation algorithm. Upon comparing the intensity compensation algorithm of an ideal system with the corrected intensity compensation algorithm, we reveal that the recovered precision of the curvature sensor can be greatly improved by the corrected intensity compensation algorithm.

关键词： instrumentation -- detectors-methods -- numerical-techniques- image processing

A Study on the Paul-Baker System as an Instrument for Multi-object Spectrum Observation

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Chinese Journal of Astronomy and Astrophysics 2005年第5期5卷 546-556页

作者： xiang-Yan Yuan Ding-Qiang Su xiang-qun cui Gen-Rong Liu National Astronomical Observatories Nanjing Institute of Astronomical Optics ＆Technology Chinese Academy of Sciences Nanjing 210042 Department of Astronomy Nanjing University Nanjing 210093

Paul-Baker systems with 4° flat field and 5° fiat field are studied. Their light obstructions under different f/ratios of the primary mirror are analyzed. Due to the strong f/ratio of the system, a focal length extender is designed in order to match the following fiber instrumentation, and two kinds of dispersion prism correctors are designed for correcting the atmospheric dispersion. We compare the designed Paul-Baker system with LAMOST, the national major scientific project now under construction.

关键词： techniques: telescopes - instrumentation: miscellaneous

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Research in Astronomy and Astrophysics 2020年第1期20卷 1-5页

作者： Ding-Qiang Su Hua Bai xiang-qun cui School of Astronomy and Space Science&Key Laboratory of the Ministry of Education Nanjing UniversityNanjing 210023China National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology(NIAOT) Chinese Academy of ScienceNanjing 210042China

FAST,the largest single-dish radio telescope in the world,has a 500-meter diameter main reflector and a 300-meter diameter illuminated *** has a main reflector that can vary its shape,which continuously changes the shape of the illuminated area in reflector into a *** this article,we propose a quasiCassegrain system for *** detailed design results are *** a quasi-Cassegrain system only needs to add a 14.6-meter diameter secondary reflector,which is close to the size of the feed *** distance from the secondary reflector to the focus is only 5.08 m,and it has excellent image *** this quasi-Cassegrain system,the shape of the illuminated area in the main reflector continuously changes into an optimized *** this quasi-Cassegrain system from frequency 0.5 GHz to 8 GHz,the multi-beam system can include 7 to 217 *** this system is used in combination with Phased Array Feed(PAF)technology,more multi-beam feeds or a higher working frequency can be used.

关键词： telescope techniques:miscellaneous methods:miscellaneous instrumentation:miscellaneous surveys

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 xiang-qun cui Ye-Ping Li Xiu-Shan Pan Ying Fu National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of ScienceNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology 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

Data-driven Seeing Prediction for Optics Telescope:from Statistical Modeling,Machine Learning to Deep Learning Techniques

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Research in Astronomy and Astrophysics 2022年第12期22卷 152-165页

作者： Wei-Jian Ni Quan-Le Shen Qing-Tian Zeng Huai-Qing Wang xiang-qun cui Tong Liu College of Computer Science and Engineering Shandong University of Science and TechnologyQingdao 266510China Nanjing Institute of Astronomical Optics&Technology National Astronomical ObservatoriesNanjing 210042China

Predicting seeing of astronomical observations can provide hints of the quality of optical imaging in the near future,and facilitate flexible scheduling of observation tasks to maximize the use of astronomical *** approaches to seeing prediction mostly rely on regional weather models to capture the in-dome optical turbulence *** to the developing of data gathering and aggregation facilities of astronomical observatories in recent years,data-driven approaches are becoming increasingly feasible and attractive to predict astronomical *** paper systematically investigates data-driven approaches to seeing prediction by leveraging various big data techniques,from traditional statistical modeling,machine learning to new emerging deep learning methods,on the monitoring data of the Large sky Area Multi-Object fiber Spectroscopic Telescope(LAMOST).The raw monitoring data are preprocessed to allow for big data *** we formulate the seeing prediction task under each type of modeling framework and develop seeing prediction models through using representative big data techniques,including ARIMA and Prophet for statistical modeling,MLP and XGBoost for machine learning,and LSTM,GRU and Transformer for deep *** perform empirical studies on the developed models with a variety of feature configurations,yielding notable insights into the applicability of big data techniques to the seeing prediction task.

关键词： methods:data analysis methods:statistical 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

作者： En-Peng Zhang xiang-qun cui Guo-Ping Li Yong Zhang Jian-Rong Shi Yong-Heng Zhao National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Optical Astronomy Chinese Academy of Sciences Nanjing Institute of Astronomical Optics and Technology National Astronomical Observatories Chinese Academy of Sciences

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

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

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