在大口径、快焦比非球面的补偿检验中，入射光线在短距离内发生大角度急剧折转，导致干涉仪面形检验结果图像产生非线性畸变，严重影响了数控小磨盘抛光的位置精度和误差去除效率。为了校正离轴非球面在补偿检验中产生的图像畸变，提出了一种校正非线性畸变图像的方法，通过同心环带法确定畸变中心位置并利用光线追迹建立被检镜到干涉图的映射关系。针对某一光学系统的520 mm×250 mm的离轴抛物面主镜进行了畸变图像的校正，校正结果面形与工件面形的位置偏差降到1 mm以下，满足小磨盘抛光的工作要求。

In the null testing of large-diameter and fast-ratio aspherical mirrors, the incident light rays are sharply turned at a large angle within a short distance, resulting in nonlinear distortion of the test result of the interferometer, and the positional accuracy and error removal efficiency of the computer controlled optical surfacing (CCOS) polishing are seriously affected. In order to correct the image distortion of off-axis aspherical mirror in compensation test, a method for correcting the nonlinear distorted image was proposed. The center position of the distortion was determined by the concentric annular method and the mapping relationship between the tested mirror and the interferogram was established by using ray tracing .In addition,the distortion of a 520 mm×250 mm off-axis paraboloid primary mirror of an optical system was corrected.Results show that the position deviation between the correction result and the surface map of the workpiece is reduced to less than 1 mm, which meets the working requirement of CCOS polishing.