利用相位差异技术检测离轴三反光学系统的波前误差

阐述了基于相位差异(PD)的波前传感技术的基本原理,针对该技术的目标函数变量多、非线性程度高等特点,提出了基于遗传算法的相位差异技术。开展了利用相位差异技术实现离轴三反光学系统在不同装调阶段的波前检测,结合干涉检验方法设计了针对扩展目标的相位差异高分辨率成像和相位估计对比实验。通过定量移动高精密平台获得焦面和离焦图像,并将解算的波前图与干涉仪的检测结果进行定量比对,验证了相位差异技术提高成像质量和正确解算波前相位信息的能力。实验结果表明,对于粗装调的光学系统,估算的波前和干涉检验结果偏差的均方根(RMS)值仅为0.0329λ;对于装调完成后的系统,相位差异技术的检测偏差RMS值小于0.013λ。

Wavefront Error Testing of Off-Axis Three-Mirror Anastigmatic System Using Phase Diversity Technology

The basic principles of wavefront sensing based on phase diversity (PD) technology are expatiated, and the genetic algorithm (GA) is proposed to be applied in the data post-processing of PD testing aiming at dealing with the multi variables and the highly nonlinearity of merit function. The wavefront error of an off-axis three-mirror anastigmatic (TMA) system is tested with PD technology based on extended target, in which the defocused image is obtained by shifting the image plane. To verify the improvement of image quality and phase estimation of PD technology, a comparison experiment of extended object on high-resolution imaging and phase estimation is carried out based on the PD and interferometric testing. It can be observed that the deviation of root mean square (RMS) between the wavefront error obtained by PD testing and by interferometric testing is 0.0329λ (RMS) for the coarse-aligned off-axis TMA system, and the deviation decreases to 0.013λ (RMS) when the system is well aligned. The precision of PD technology can satisfy the requirement of engineering. The imaging experiments are also carried out and image quality can be well improved according to the wavefront estimated by PD.