分层共轭自适应光学系统扩大校正视场的方法研究

Exploration of Enlarge Correcting Field for Multi-conjugation Adaptive optical system

为了扩大自适应光学(AO)系统的校正视场,本文分析了在主要湍流层的共轭面上设置多个变形反射镜(DM),即采用分层共轭自适应光学(MCAO)的方法。在自适应光学系统中,角度的非等晕性产生的波前误差主要取决于校正的模式数、大气介质折射率结构常数(C2n)的分布和系统的几何尺寸。文中阐述了一种基于泽尼克多项式空间校正函数的非等晕性计算方法,并进一步给出了在多激光导星(LGS)配合下,用一个夏克-哈特曼(SH)曲率传感器测量两个湍流层强度起伏的算法。结果表明,对于孔径为3.5m的望远镜,利用两个变形反射镜能够达到3弧分的校正视场。

In order to increase the corrected field of view （FOV） of an adaptive optics （AO） system, this paper proposed to place several deformable mirrors （DMs） in the conjugate planes of the dominant turbulent layers （multi -conjugate adaptive optics, MCAO）. The wave -front error caused by angular anisoplanatism in an MCAO system depends on the number of corrected modes, the Cn^2 - profile and the geometry of the system. We present a new approach of calculating the anisoplanatism by using spatial correlation functions of Zernike modes, and we also present a new scheme of measuring the individual wave - front distortion of each of the dominant two layers with one Shack - Hartmann or a Shack - Hartmann - Curvature sensor per guide star using the intensity fluctuations （scintillation） caused by the turbulence. The result shows that for the Calar Alto 3.5m telescope, a setup consisting of two deformable mirrors would result in a corrected field of view of three arcminutes.