Wang Ruoyan, Gao Zhishan, Zhu Dan, Liu Weijian, Ji Wen, Guo Zhenyan, Wang Dasen, Wang Lingjie, Xu Yao, Yuan Qun
Appl Opt. 2020 May 1;59(13):4176-4182. doi: 10.1364/AO.388515.
Subaperture stitching interferometry (SAS) is an important method for map testing of large aperture optical components, in which a mechanical structure is often employed for the testing of each subaperture. By eliminating the phase deviation of the corresponding points in the overlapping regions of every adjacent subaperture, the whole aperture map can be obtained. Accurate subaperture positioning is an important guarantee for precise stitching. In this paper, a hybrid optimization algorithm is proposed to realize subpixel-level positioning accuracy in SAS based on the combination of the phase correlation and iterative gradient methods. The phase correlation method is adopted to calculate the pixel-level positioning deviation first, and the subpixel deviation is derived and then corrected by iterative optimization through the gradient method. The subpixel-level positioning accuracy of the proposed optimization algorithm is verified by simulations and a 76.2 mm off-axis parabolic mirror is chosen as an experimental testing sample. The surface map obtained from the proposed hybrid optimization method is consistent with the full aperture testing result, which also verifies that the proposed optimization algorithm is a powerful tool with subpixel-level positioning accuracy in SAS testing.
子孔径拼接干涉测量法（SAS）是大口径光学元件面形检测的一种重要方法，其中每个子孔径的检测通常采用机械结构。通过消除相邻子孔径重叠区域对应点的相位偏差，可获得整个孔径的面形。精确的子孔径定位是精确拼接的重要保证。本文提出一种基于相位相关和迭代梯度方法相结合的混合优化算法，以实现SAS中像素级的定位精度。首先采用相位相关方法计算像素级定位偏差，然后通过梯度法进行迭代优化得到亚像素偏差并进行校正。通过仿真验证了所提优化算法的亚像素级定位精度，并选取了一个76.2mm离轴抛物面镜作为实验测试样品。所提混合优化方法得到的面形与全孔径检测结果一致，这也验证了所提优化算法是SAS检测中具有亚像素级定位精度的有力工具。
