基于波长移相调谐的多表面干涉研究

为了解决不同厚度下平行平晶的多表面干涉效应对光学元件面形检测的影响,提出了基于波长移相调谐原理的多表面干涉面形检测方法。根据波长移相调谐原理,推算出不同厚度下被测元件与测试腔长的比例关系,通过对多表面干涉图进行离散傅里叶变换,进而提取出平行平晶前后表面面形的相位信息。实验结果表明:与ZYGO公司GPI干涉仪测量结果对比,厚度分别为10mm和40mm的两块平行平晶,测试结果偏差很小,验证了算法的有效性。

Mutiple Surfaces Interference Testing Based on Wavelength-Tuned Phase Shifting

To eliminate the effect of multi-surface interferometric effect on the profile measurement of the transparent ele- ments with the different thickness, an interferometric fringe measuring method was proposed based on wavelength tuning and Fourier transform. According to the principle of wavelength-tuned phase shifting, the relationship between the testing cavity length and the element with the different thickness was obtained. And then, with disperse Fourier transform for the group of interferograms, the frequency information for the front surface, back surface of the measured element was extracted and the accurate surface information were obtained through a reconstruction algorithm. Experimental results indicate that the deviation is small compared with the ZYGO GPI Interferometer. It also indicates that the algorithm is reliable.