基于两帧差分平均移相算法标定斐索型波长移相干涉仪

Calibration of Fizeau Wavelength-Tuned Phase-Shifting Interferometer Based on Two-Frame Differential Average Phase-Shifting Algorithm

波长移相干涉仪的移相值与干涉腔长度有关,需要对其标定方可采用定步长移相算法计算相位分布。为了标定研制的斐索型波长移相干涉仪,提出一种利用干涉图直接计算定步长移相值的新算法两帧差分平均移相算法(TDA)。对该算法进行模拟仿真,验证了算法的可行性和计算精度,并进一步开展了实验研究。结果表明:运用TDA算法处理定步长移相干涉图可以获得与实际值接近的计算结果;利用TDA算法标定的波长移相干涉仪的测量面形均方根(RMS)重复性优于0.07nm(1.106λ/10000),达到了设计指标;用该干涉仪与Zygo干涉仪对相同元件进行比较测量,检测结果之差的RMS为0.742nm。

It is necessary to calibrate the optical path length before using wavelength-tuned phase-shifting interferometer based on fixed step phase-shifting algorithm to compute the phase distribution, as the precision of measurements depends on the step value. To implement the calibration for the interferometer, a new algorithm named two-frame differential average phase-shifting algorithm （TDA） is proposed to calculate phase shift directly by using the interference figure. Simulation and theory analysis are adopted to verify the accuracy and practicability of the algorithm. Furthermore, related experiments are made. The result indicates that by handling the fixed step phase-shifting interferograms with TDA, the result which matches well with the real value can be obtained~ the root mean square （RMS） repeatability is better than 0. 07 nm（1. 106）t/10000）, which meets the design index; by comparing the measurement results for the same component with this interferometer and Zygo interferometer, the RMS of the difference is 0. 742 nm.