一种大视场望远镜误差校正方法的研究

An Error Correction Method Research Based on Large Field Reflecting Telescope

基于两镜反射式望远镜系统,以主镜为基准,分析了当非球面次镜由于偏心、倾斜、主次镜间距产生变化时对望远镜系统波前像差的影响。根据理论分析,提出了一种望远镜系统误差校正的方法。该方法先后以轴上视场光斑的半径和全视场光斑的平均半径作为成像质量的评价指标,利用随机并行梯度下降算法对次镜的位置进行调整,最终使全视场光斑半径的平均值收敛到极值,即认为成像质量达到最佳。针对里奇-克列基昂(R-C)结构望远镜系统进行了仿真分析。结果表明,次镜位置调整后能够使视场内所探测的光斑半径的平均值收敛到极值。该方法使望远镜系统误差的校正具有外在标准,能够使望远镜在观测过程中进行校正。

For a two-mirror reflecting telescope, if the position of primary mirror is set as standard, the influences of de-center, tilt of a aspheric secondary mirror and de-space between primary and secondary mirrors on wavefront aberration of the felescope are analyzed. An error correction method of the telescope is proposed based on the theory. The method firstly uses the radius of spot diagram on axis and secondly uses the mean radius of all fields spot diagrams as performance metric of imaging quality. The position of secondary mirror is adjusted by stochastic parallel gradient descent （SPGD） algorithm. Finally, the mean radius of all fields spot diagrams converge to regard as the situation of best imaging quality. The process is achieved in a Ritch-Chretien （R-C） telescope by computer simulation, and the results show that the correction of secondary mirror makes the mean radius of all fields spot diagrams converge. The method gives the error correcting of the telescope an external standard and can be used to correct error in observation process of the telescope.