在卡式系统的后光路中加入倾斜的平板, 实现同轴透射端可见光的接收及反射端红外光的发射。该卡式系统口径为400 mm, 焦距为4 000 mm, 视场为±1.5′, 加入平板后会给系统造成较大的像差, 为了达到系统设计要求: 角分辨率小于1″, MTF曲线在35.7 lp/mm处高于0.6。分析了倾斜平板产生的像差, 对比不同材料和厚度的平板对像差的影响。通过加入偏转的双胶合透镜校正像差, 但该方法会使系统的出瞳位置发生变化, 从而提出使用偏转三胶合透镜保证出瞳位置的校正方法, 并对加入的透镜进行公差分析, 最终达到设计指标。

The tilted optical flat was added to the Cassegrain system to achieve the reception of visible light and the emission of infrared light at the coaxial transmission end. The Cassegrain system had an aperture of 400 mm, a focal length of 4 000 mm and a field of view of ±1.5′, which could have greater aberration after adding the tilted optical flat. In order to meet the designed requirements, the angular resolution less than 1″ and the modulation transfer function (MTF) greater than 0.6 at 35.7 lp/mm,we analyzed the aberration caused by tilted optical flat and compared the effects of plates with different materials and thicknesses on the aberration. The aberration was corrected by adding the deflected double cemented lenses, but this method made the exit pupil position changed . Hence an alternative method was proposed to fix the pupil position by adding the deflected cemented triplet lenses .Subsequently, the tolerance analysis for the added lenses was done ,and finally the design target was achieved.