摘要
太阳望远镜复杂的观测环境会引起机电型边缘传感器的零点漂移。采用光学探测的方法对边缘传感器进行短周期定标,解决太阳望远镜中传感器零点漂移的问题。为验证光学探测技术对边缘传感器进行短周期定标的可行性,开展了基于点扩散函数的子镜边缘探测研究。利用促动器、边缘传感器以及点扩散函数互相关检测法进行交叉定标实验,其检测精度优于5 nm,并在两镜系统上开展了基于点扩散函数边缘探测的主动控制实验。实验结果表明,该方法的探测精度和探测频率满足对边缘传感器的短周期定标。
The 8-meter ring segmented primary mirror is one of the important alternatives for China Giant Solar Telescope plan.The active control technology of the segmented mirror is the key to realizing the high spatial resolution of the segmented solar telescope.In the active control of the ring segmented mirror,high precision edge detection and tip/tilt detection are important factors in determining the co-phase maintenance of the primary mirror.In the current CGST active segmented scheme,the piston error of the segmented primary mirror is detected and corrected by the electromechanical edge sensors.However,in solar observations,the daytime temperature fluctuates greatly,and the primary mirror surface is affected by solar thermal radiation to generate temperature gradients.The primary mirror temperature control is required to improve mirror seeing.The temperature of the telescope truss system will also change due to the influence of thermal radiation.Therefore,the complex observation environment of the solar telescope will cause the zero-point drift of the electromechanical edge sensor,which will gradually increase the figure error of the primary mirror and will not be able to maintain the co-phase for a long time.To solve the problem of the unstable zero-point of the electromechanical edge sensor in the solar telescope,it is necessary to find a short-period calibration method for the electromechanical edge sensor,and the calibration period is about tens of seconds to several minutes.The accuracy of edge detection is better than 5 nm,and CGST can achieve the co-phase maintenance of the primary mirror in visible or near infrared.Therefore,the calibration accuracy of the edge sensor needs to be better than 5 nm.The optical co-phase detection technology detects the figure error of the primary mirror and the phasing error,and measures the absolute position of the segments.The short-period calibration of edge sensors of segmented solar telescopes using the optical detection technology is an optional solution.In this paper,in order to verify the feasibility of short-period calibration of edge sensors with the optical detection technology,edge detection research based on point spread function is carried out.Cross-calibration experiments are carried out using actuators,edge sensors and point spread function cross-correlation detection.The detection error level of this method is evaluated,and an active control experiment based on point spread function edge detection is carried out on a two-mirror system.In the 5-hour active control experiment,the RMS of the tilt/tip change of the segmented mirror is maintained at 0.01″,the RMS of the edge height change of the segmented mirror is maintained at 6.33 nm,and the RMS of the figure error of the segmented mirror is maintained at 18.73 nm.The experimental results show that the optical edge detection can accurately reflect the change of the position state of the segments in the active control,and the edge detection accuracy is better than 5 nm.The edge detection accuracy and detection frequency based on the point spread function satisfy the short-period calibration of edge sensors.The research results provide a reference for the active maintenance of the ring segmented solar telescope in the near infrared or visible light.
作者
王斌
戴懿纯
许方宇
金振宇
WANG Bin;DAI Yichun;XU Fangyu;JIN Zhenyu(Astronomical Technology Laboratory,Yunnan Observatory,Chinese Academy of Sciences,Kunming 650216,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2022年第12期1-10,共10页
Acta Photonica Sinica
基金
国家自然科学基金(No.11573068)
国家自然科学天文联合基金(Nos.U1531110,U1831134)。
关键词
太阳望远镜
拼接镜面
边缘探测
光学定标
主动控制
Solar telescope
Segmented mirror
Edge detection
Optical calibration
Active control
