考虑二次反射条纹的透明被测件多表面干涉测量

Multi-surface wavelength-tuning phase-shifting interferometry with parasitic fringes

为了实现多表面干涉测量,提出了一种基于最小二乘原理的迭代移相算法。通过将二次反射信号纳入最小二乘求解方程中,进一步提高干涉测量精度。根据最小二乘原理将理论值与实际干涉信息相联系从而构建最小二乘方程,该方程分为两部分:初始相位的迭代计算和每两帧之间的移相值的迭代,通过21帧干涉图的迭代结果,求解得到较为准确的初始相位分布。仿真结果表明,不考虑二次反射信号的求解精度为10 nm,将该信号纳入计算以后可将求解精度提高到0.3 nm。通过实测数据的实验结果可知,该算法可以求解出较为精确的相位分布,并且求解结果中没有杂波干扰和谐波信号残余,能够实现多表面透明透镜的高精度测量。

In this study,an iterative phase-shifting algorithm based on the least-squares principle was developed to achieve multi-surface interferometry.The accuracy of interferometry was further improved by incorporating the secondary reflection signal into the least-squares solution equation.First,according to the least-squares principle,the theoretical value was correlated with the actual interference information to derive the least-squares equation.This derived equation was divided into two parts:the iterative calculation of the initial phase and the iteration of the phase-shifting value between two successive frames.From the iterative results of 21 interferograms,an accurate initial phase distribution was obtained.The simulation results show that the solution accuracy without considering the secondary reflection signal is 10 nm,and the accuracy improved to 0.3 nm when the signal is considered in the calculation.In addition,the experimental results of the measured data indicated that the developed algorithm can be used to reconstruct a more accurate phase distribution,and no clutter interference or residual harmonic signal is observed in the results.Therefore,the developed algorithm can be used to achieve high-precision multi-surface measurement,which has research value and practical significance.