亚秒级甚高精度星相机光学系统设计

Optical System Design of Star Camera with High Precision Better than Second Level

高精度星相机是航天测绘、侦查相机实现精确定位测量的关键设备。分析了长焦距星相机光学系统设计难点,采用新型双高斯向远摄型过渡的结构型式,设计了精度达到亚秒级的星相机光学系统。光学系统焦距为200 mm,相对孔径为F/2,视场角为7.5°×7.5°,光谱范围为500~800 nm。针对恒星色温范围大的特性,在未采用特殊色散玻璃材料的情况下校正了光学系统的色差,实现不同色温恒星的质心位置一致性;采用负折射率温度系数的冕牌玻璃进行热补偿,实现光学系统对恒星探测的亚秒级无热化设计。设计结果表明:光学系统畸变优于0.003%,垂轴色差优于1.5μm,2600 K^9800 K范围内色温恒星的质心位置精度优于0.2″;在0℃~30℃范围内,焦距变化不超过5.1μm,除1视场外质心位置精度均优于0.4″。

In order to achieve accurate positioning measurement, high precision star camera is the key equipment of the space mapping or reconnaissance camera. The difficulties of optical system design about star camera with long focal length are analysized. The new structure type of dual Gauss transited to telephoto is adopted, a subsecond star camera optical system is designed with focal length of 200 mm, relative aperture of F/2, angel of 7.5°×7.5°, spectrum range of 500～800 nm. Due to the characteristics of stellar temperature in large range, the color correction of optical system is realized without the use of special dispersion glass, the consistency of centroid position is achieved under different color temperatures of stellar. In order to compensate thermal drifting, negative temperature coefficient of refract index of the crown glass is adopted, by which sub- second precision of athermalization is come true. It is shown that, the distortion of the optical system is better than 0.003%, the lateral color aberration is less than 1.5 μm, the accuracy of centroid position is better than 0.2″ in the range of2600 K～9800 K. Between 0 ℃ and 30 ℃, the change of focal length is less than 5.1 μm, the accuracy of centroid position is better than 0.4″, except the 1 field.