双点干涉法位相缺陷检测中的解相算法比较

双点光源移相干涉测量是大口径光学元件位相缺陷检测的一种重要方法。为了分析双点干涉中误差对解相算法的影响,首先给出相位缺陷检测的系统结构和理论模型,在此基础上,针对测量过程中主要存在的一次移相误差、二次移相误差、光强误差和随机振动误差,研究了Hariharan 5帧移相算法、13帧移相算法和迭代随机移相算法的解相误差,并进行了仿真分析。结果表明,针对这几种误差源,13帧算法解相精度整体优于5帧法,迭代随机移相算法解相效果优于13帧法和5帧法,当这几种误差按实际指标同时作用时,迭代随机移相算法解相误差RMS小于5帧法和13帧法,PV值稳定在0.5 nm以内。由于随机振动占主要作用,说明迭代随机移相算法受误差影响很小。

Comparison of phase extraction algorithms in testing of phase defects with two-point interference

Two-point interference is an important method in testing of phase defects in optical elements with large diameter. In order to analyze the effects of errors on phase extraction algorithms in two-point interference system, the system structure and theoretical model are given firstly. Based on it, the Hariharan 5-frame algorithm, 13-frame algorithm and the advanced iterative algorithm are studied and simulated considering the linear phase shift error, nonlinear phase shift error, intensity error and random vibration error. The result shows that the accuracy of 13-frame algorithm is generally higher than that of 5-frame algorithm and the effect of advanced iterative algorithm is better than the other two. When the errors are given according to the analysis, the RMS error of the advanced iterative algorithm is less than those of 5-frame algorithm and 13-frame algorithm, and the PV of advanced iterative algorithm is less than 0.5 nm steadily. This means that the error of advanced iterative algorithm is affected less by errors while vibration plays the major role in the errors discussed.