滚仰式红外光学系统由物镜前组、折转镜组和成像后组组成, 其平台内框架俯仰范围可达到±90°, 外框架可以实现360°滚转, 使光学系统观察视场覆盖整个前半球。光学系统实现了100%冷光阑效率。为适应较大的工作环境温度变化, 对光学系统开展了被动无热化设计, 给出了被动无热化实现的计算公式, 并利用“虚拟色差”技术, 快速确定了满足无热化条件的光学系统最优初始解。针对制冷型红外光学系统的“冷反射”效应, 给出了冷反射诱导温差(NITD)的计算公式, 并对敏感表面进行了优化控制。设计结果表明, 光学系统焦距为58 mm, 视场大小为4.0°, F数为2.0, 在-50～60℃工作温度范围内系统MTF值接近衍射极限, 并对“冷反射”效应具有较好的抑制能力。经样机测试, 光学系统成像清晰稳定, 性能良好, 满足设计及使用要求。

IR optical system of roll-elevation seeker was composed of object lens front group, turning mirrors group and imaging rear group. The pitch frame had ±90° moving range and the roll frame had 360° moving range, so that the combination of rolling and pitching enabled the optical system to realize all over the front hemisphere field. The optical system achieved 100% cold shield efficiency. In order to adapt to the large variation of working environment temperature, the athermal design was used, and the formulas to realize athermal design were given. By using the technique named dummy chromatic aberration, the best initial solution of athermal design was found quickly. For controlling the Narcissus effect of this cooled IR optical system, the formula to compute the NITD were given, and the sensitive surface of Narcissus effect was optimized. The design result showed that the optical system working parameters were the effective focal length of 58 mm, field of view of 4.0°, F/# of 2.0, and the MTF of the optical system was close to the diffraction limit when working temperature changed from -50 ℃ to 60 ℃. The narcissus effect was also controlled effectively. The optical system met the design requirements by imaging test.