下一代地基或天基大型望远镜系统多采用拼接式主镜实现。受多个误差源的干扰,拼接式主镜中的子镜面容易偏离设计位置而发生刚性失调,其中,子镜沿着光轴方向的piston误差和绕子镜面内旋转轴的tip/tilt误差尤为突出,对拼接式主镜系统的成像质量产生了严重的影响。从统计的角度出发,解析研究了由piston误差及tip/tilt误差导致的失调非连续波前的统计特性;推导了失调拼接式光学系统的像场质心;基于Maréchal近似,结合失调波前的统计特性,计算了斯特列尔比。研究结果进一步丰富了人们对拼接式成像系统性能的理解。

The segmented primary mirror is employed to construct the next-generation ground- and space-based large telescopes. Because of many disturbances, the segmented mirrors within the segmented primary mirror easily deviate from the desired position, leading to rigid misalignment. In particular, the piston error of segmented mirror along the direction of local optical axis and the tip/tilt error seriously affect the imaging quality. The statistical properties of the misaligned discontinuous wavefront caused by piston and tip/tilt errors and the centroid of the image field of the misaligned segmented optical system are analytically evaluated from a statistical perspective. Further, the Strehl ratio is calculated based on the Maréchal approximation by combining the statistical properties from the random discontinuous wavefront. The results of this study can be used to improve the understanding of the performance of the segmented imaging system.