子孔径拼接检测大口径非球面技术的研究

Testing of large aspheric surfaces by subaperture stitching interferometry

为了无需其他辅助光学元件就能够实现对大口径非球面的测量,提出了子孔径拼接干涉检测方法。并基于齐次坐标变换、最小二乘法以及Zernike多项式拟合建立了综合优化和误差均化的拼接数学模型;开发了子孔径拼接检测非球面算法软件,进行了计算机模拟和仿真实验;设计和搭建了子孔径拼接干涉检测装置,并利用子孔径拼接实现了对口径为350 mm的双曲面的检测;为了分析和对比,对待测非球面进行零位补偿检测实验,子孔径拼接所得的面形分布和零位补偿检测所得的全口径面形分布都是一致的,其面形误差PV值和RMS值的偏差分别为0.032λ和0.004λ(λ=632.8nm)。从而提供了除零位补偿检测外另一种定量测试非球面尤其是大口径非球面的手段。

In order to test large aspheric surfaces without the aid of null optics, the subaperture stitching interferometry （SSI） was proposed. The theory and principle of the technique were analyzed, the optimized stitching model and effective stitching algorithm were established based on homogeneous coordinates transformation, simultaneous least-squares method and Zernike polynomials fitting. The software of SSI was designed, and the computer simulation was carried out, the prototype for testing of large asphere by SSI was designed and developed. The experiment was conducted with five subapertures for a Ф350 mm hyperboloid. For comparison and validation, the asphere was tested by null compensation as well, the synthesized surface map is consistent with the entire surface map from the null test; and the difference of PV and RMS error between them was 0. 032 λ and 0. 004λ（λ=632.8 nm）, respectively.