反射式内掩日冕仪的光学设计与杂散光分析

日冕仪的工作特点决定了其对杂散光抑制要求极其严格。根据反射式日冕仪的工作特点，通过分析其光学特性以及其抑制系统杂散光的基本原理，设计了反射式内掩日冕仪系统。其中，视场0.67°、口径47mm、焦距768mm、系统总长1200mm，系统在30lp/mm处的MTF值大于0.6，弥散斑半径小于2.5um，成像质量达到衍射极限。通过分析系统杂散光特点，建立了消杂散光结构，使得系统的主要杂散光源被全部抑制。本系统可做到大约10-6-10-8B⊙的杂散光抑制水平，可以实现对日冕的清晰成像观测。

Stray light analysis of internally occulted mirror coronagraph

The principle of coronagraph requires that stray light in coronagraph system must be kept at an extremely low level. Based on the principle of mirror coronagraph, the internally occulted mirror coronagraph is designed by analyzing its optical character and the basic rules of suppressing the stay light. In this system, the FOV is 0.67degree, the aperture is 47mm, the focal length is 768mm, the total length is 1200mm, the MTF value at 30lp/mm is above 0.6, the radius of spot is less than 2.5 um,and the image quality of the system approaches the diffraction limit.Considering the character of stray light in system,the structure of suppressing stray light is built.In the system,the main sources of stray light can be suppressed entirely .The system can achieve a level of 10-6-10-8B⊙ approximately in suppressing stray light,and so it can get high quality coronal images.