一种小口径凸非球面补偿器的设计

Design of Compensator of Convex Aspheric Surface with Small Apertures

离轴三反光学系统目前常被多谱段共口径光学系统作为共口径端,检测离轴三反光学系统中凸非球面次镜时,需要通过补偿法来实现非球面的高精度检测,因此补偿器的优化设计是关键技术之一。对于二次曲面系数较大同时背面为非透射面的小口径凸非球面,无法采用非球面透射式的补偿法进行检测,因此采用凸非球面直接作为反射面的自准直平行光补偿检验法。根据设计思路,利用Zemax软件构建初始结构并对其进行优化,这样简化了初始结构计算过程,同时能得到理想的补偿器系统结构。给出了一个口径为80 mm、二次曲面系数为-6.5,F数为5.00375的凸非球面反射镜的补偿器系统的设计过程和公差分析过程,系统工作波长为632.8 nm,均方根值为0.000015λ,公差分配后残余波像差为0.0104708λ。

While testing the secondary mirror with convex aspheric of off-axis three-mirror optical system, compensation method is used to achieve high-precision aspheric testing. Thus design of compensator is a key technology. Compensation in transmission form can＇t be used for small-caliber convex aspheric surface with great quadratic surface coefficient and non-transmissive back surface. So the convex aspheric surface is directly taken as a reflection in auto-collimation parallel light compensation test. According to the design ideas, the initial structure is built by the Zemax firstly, which simplifies the calculation of the initial structure, and can get the desired compensation system structure. The design and tolerance analysis process of convex aspheric secondary mirror compensator system is given with the diameter of 80 mm, the quadratic surface coefficient of -6.5, and the F number of 5.00375. The system operating wavelength is 632.8 nm. The root mean square （RMS） of wavefront error is 0.000015λ. Analysis results show that the total residual wave aberration of the system is 0.0104708λ, which satisfies the requirement of assembling accuracy.