大口径光学元件功率谱密度的拼接干涉检测

Power Spectral Density Test of Large Aperture Optical Elements by Stitching Interferometry

为实现大口径光学元件波前功率谱密度(PSD)的高精度、低成本检测,提出了一种将干涉与拼接技术结合的检测方法。推导了波前PSD的计算方法,提出了基于相关匹配的子孔径拼接算法,分析了拼接干涉检测的误差来源。对拼接检测算法进行了仿真验证,结果表明,拼接检测的波前畸变峰谷值(d_(pv))与PSD的均方根值(P_(RMS))的相对偏差分别为1.2%和0.1%。采用口径为620 mm×450 mm光学元件开展了5次拼接检测实验,比较了拼接检测与全口径直接检测结果,两者分布一致,d_(pv)偏差不大于0.012λ(λ=632.8 nm),P_(RMS)偏差不大于0.03 nm,表明该算法稳定可靠,可实现大口径光学元件波前PSD的拼接检测。

In order to realize high-precision and low-cost detection of wavefront power spectral density(PSD) of large aperture optical elements, a detection method combining the interference and splicing techniques is proposed. The method for calculting the wavefront PSD is deduced, and the subaperture stitching method is proposed based on the correlation match algorithm. Then the error sources in the stitching interferometry are analyzed. The simulation by the stitching method is performed and the results show that the relative deviations of the wavefront distortion peak-valley value(dpv) and the root mean square value(PRMS) of the PSD during the stitching detection are 1.2% and 0.1%, respectively. Five experiments with 620 mm×450 mm aperture elements are accomplished and the corresponding stitching results are compared with the direct test results of the full aperture elements. The distributions are consistent with each other. The deviation of dpv is 0.012 λ(λ=632.8 nm) and that of PRMS is 0.03 nm, which indicating the proposed mehtod is stable and reliable for the stiching test of wavefront PSD of large aperture optical elements.