Active compensation of aberration for large ground-based telescope based on Hexapod platform

被引：0
|
作者：
Cao Y.-Y. [1 ,2 ]
Wang J.-L. [1 ]
Chen T. [1 ]
Lü T.-Y. [1 ]
Wang H.-H. [1 ]
Zhang Y. [1 ]
Wang F.-G. [1 ]
机构：
[1] Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun
[2] University of Chinese Academy of Sciences, Beijing
来源：
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | 2020年 / 28卷 / 11期
关键词：
Active compensation; Finite element; Ground-based telescope; Misalignment error; Nonlinear least square fitting;
D O I：
10.37188/OPE.20202811.2452
中图分类号：
学科分类号：
摘要：
As the diameter of a ground-based telescope increases, the image quality will significantly degrade because of optical misalignment, which is caused by gravity and thermal deformations of the telescope structure. To accurately estimate the misalignment error, a mechanical model of a telescope was established, and the computation method and compensation process were investigated. According the structural components of the telescope, the structural model was simplified, and then the mechanical model was established using the finite element method. Based on nonlinear least square fitting, a method was presented to compute the misalignment error between the primary and secondary mirrors in which the inputs were the current node position of the primary and secondary mirror surfaces. Thereafter, a method in which the optical axis of the primary mirror used as the benchmark were adopted to determine the length of the hexapod leg with the objective of compensating for the misalignment error. Finally, numerical examples of a ground-based telescope with a diameter of 2 m were presented to verify the presented methods and the corresponding theories. The simulation results show that there are obvious misalignment errors because of gravity and thermal deformations, with maximum root mean square (RMS) radii of the optical spots being 1 473 and 557 μm, respectively. After the secondary mirror compensation, the RMS radii of the spots are decreased significantly, with all of them being <32 μm. The results verify the misalignment error and the hexapod leg length computation methods. © 2020, Science Press. All right reserved.
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页码：2452 / 2465
页数：13
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