For space debris observation camera, ultra-high precision star sensor and other devices for detecting weak point targets, large-caliber compact and high-quality optical system is the key factor to realize sub-second sub-second detection accuracy. The major influence on the attitude measurement precision of the star sensor is that the optical axis error, the optical system focal length error, the optical axis deviation error, the focal plane tilt error and the optical distortion correction residual error caused by the temperature change caused by the change of the optical performance of the lens group Bias errors such as low frequency error. By the space room Wang Hu, Liu Jie, Xue Xike, who invented the patent "dark spot-like target detection using sub-second-class large-aperture compact optical structure," a good solution to the above problems, making the optical system thermal stability And high quality effectively reduce the low-frequency error, has recently been authorized by the invention. The optical length of the system is 175mm (equivalent to the aperture size) and the focal length is 320mm. It is the first star sensor optical system with the largest caliber and the longest focal length in China. The system has introduced a number of technologies such as no heating, light miniaturization and stray light suppression. Among them, the design principle that the secondary mirror and the aperture correction mirror are coplanar and the aperture correction mirror are applied multiple times in the optical path and other special layouts shorten the optical total length, so that the system aperture is equivalent to the total length of the optical system. The secondary mirror hood and The center of the aperture correction lens is connected through a through hole, effectively reducing the influence of obscuration and stray light multiple reflections and obtaining good stray light suppression effect. The whole optical system has the advantages of good image quality, energy concentration, dispersive spot and color deviation and small color distortion, which is beneficial to the realization of sub-second-level detection precision. It is suitable for ultra-precision star sensors and dark-field targets such as space debris Probe. The embodiment of this invention patent has been successfully applied to the day boat number one cargo spacecraft. Fj40 Slave Cylinder,Fte Clutch Slave Cylinder,T5 Internal Slave Cylinder,Td42 Clutch Slave Cylinder RUIAN ZHUOLI AUTO PARTS CO.,LTD. , https://www.zhuoliauto.com