Zeng Xuefeng, Zhang Xuejun, Xue Donglin, Zhang Zhiyu, Jiao Jian
Appl Opt. 2018 Dec 1;57(34):F56-F61. doi: 10.1364/AO.57.000F56.
Distortion can be introduced in null testing using computer-generated holograms for off-axis aspheres or freeforms with significant deviation. It leads to the failure of testing results to guide deterministic optical processing. In this paper, based on ray tracing and calibration marks applied to a mirror surface, a high-accuracy method is proposed to correct the distortion. The correction error is less than 1 mm. Second and fourth mirrors of a reflective telescope prototype with an F number of 6.5 and field of view of 76° are polished. In the process, distortion is corrected, and the position misalignment error is as small as 0.783 mm. For the sake of alignment, the two mirrors are fixed on a 790 mm×390 mm SiC substrate. The root-mean-square value of the mirror surface error is 0.0433λ (λ=0.6328 μm) after ion beam finishing.
在使用计算机生成全息图对离轴非球面或具有显著偏差的自由曲面进行零位测试时，可能会引入像差。这会导致测试结果无法指导确定性光学加工。本文基于光线追迹和应用于镜面的校准标记，提出了一种高精度的像差校正方法。校正误差小于1毫米。对一台F数为6.5、视场为76°的反射望远镜原型的第二和第四面镜进行了抛光。在此过程中，校正了像差，位置对准误差小至0.783毫米。为了对准，将这两面镜固定在一块790毫米×390毫米的碳化硅基板上。离子束抛光后，镜面误差的均方根值为0.0433λ（λ=0.6328微米）。
