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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。
The phase shift of the wavelength phase-shifting interferometer depends on the length of the interfering cavity. The calibration of the phase-shift interferometer is required to calculate the phase distribution using the step-by-step algorithm. In order to calibrate the developed Fizeau wavelength phase-shifting interferometer, a novel two-frame differential average phase shift algorithm (TDA) is proposed based on the new algorithm of interferogram to directly calculate the long-term phase shift. The algorithm is simulated, the feasibility and accuracy of the algorithm are verified, and further experimental research is carried out. The results show that the TDA algorithm can be used to process the fixed-step phase-shifted interferograms and get the approximate results with the actual values. The RMS of the measured wavelength-phase interferometer with TDA algorithm is better than 0.07 nm (1.106λ / 10000), reaching the design index; using the interferometer and the Zygo interferometer to compare and measure the same components, the RMS of the difference between the test results is 0.742 nm.