为了消除平行平板类光学元件的多表面干涉效应对元件面形测量的影响, 提出了基于波长移相调谐技术与傅里叶变换原理的多表面干涉条纹检测技术。首先, 根据波长移相原理和被测元件的厚度, 按照推算出的被测腔长与元件厚度间的比例关系正确摆放被测元件的测试位置。然后, 通过波长移相技术采集一组干涉图。最后, 对这组多表面干涉图进行离散傅里叶变换, 提取带有被测元件前后表面面形的频率信息以及厚度变化的频率信息, 通过重构算法得到准确的面形信息和厚度信息。实验结果表明: 与传统的13步移相算法相比, 得到的前表面PV值和RMS值分别相差0.003和0.001, 而后表面PV值与RMS值分别相差0和0.001。这些结果基本满足平行平板类光学元件面形的高精度测量与洁净测量的要求。

To eliminate the effect of multi-surface interferometric effect on the profile measurement of transparent elements, an interferometric fringe measuring method was proposed based on wavelength tuning and Fourier transfer. Firstly, according to the principle of wavelength-tuned phase shifing and the thickness of the element to be measured, the element was put a proper position in the test accordance with the proportional relation between cavity length and element thickness. And then, a group of interferograms were captured by the wavelength phase-shifting technology. Finally, with disperse Fourier transform for the group of interferograms, the frequency information for the front surface, back surface and thickness variation of the measured element was extracted and the accurate surface information and thickness information were obtained through a reconstruction algorithm. Experimental results indicate that the differences of PV and RMS for the front surface are 0.003 and 0.001, and those for the back surface are 0 and 0.001 respectively as compared with the traditional 13-step phase-shifting interferometry. These results satisfy the system requirements of the high precision test and the lustration test of the elements.