设计了一个F数为2，工作波段为3.7~4.8 μm，全视场2ω=111.2°的高分辨率制冷型中波广角红外成像光学系统。该系统采用二次成像构型，通过Si、Ge、ZnSe三种材料六片式对称布局，利用折/衍混合器件及非球面,实现了光学被动消热差设计，使系统在-55 ℃至+80 ℃的宽温范围内，在空间频率为33 lp/mm处的光学传递函数（MTF）均大于0.4，系统在15 μm的像素尺寸内，能量集中度大于70%；采用f-θ设计，使成像系统对不同视场具有相同的角分辨率；通过引入光阑像差和控制像方视场角，使像面具有较好的均匀性，边缘视场最低相对照度为中心视场的90.9%，且具有近100%的冷光阑效率，同时，系统具有较好的冷反射抑制效果，该光学系统适用于像素为15 μm，分辨率为640 pixel×512 pixel的中波制冷探测器。

An optical system of mid-wavelength infrared for high resolution cooled wide-angle imaging system is designed. The F-number of the system is 2 and full field of view (FOV) 2ω=111.2°. The system chooses a double imaging configuration. By introducing an diffractive optical element, setting aspheric surfaces and symmetrically distributing three types of material Si, Ge and ZnSe with 6 elements, the system is athermalized across a wide temperature range from -55 ℃ to +80 ℃ and the optical aberration is well balanced. In the athermalized temperature range, the modulation-transfer function (MTF) is higher than 0.4 at 33 lp/mm, and the diffractive radial energy is more than 70% in a circle of 15 μm. Based on the principle of f-θ lens, the wide-angle system gets the same angular resolution for different fields. By intently introducing stop aberration and specifically controlling the FOV in imaging space, the focal plane gets a very good illumination uniformity, the relative illumination of off-axis field is more 90.9% and the efficiency of the cold stop is almost 100%. Moreover, the narcissus of the system is controlled very well. This system is suitable for high resolution cold 640 pixel×512 pixel detector with pixel size of 15 μm.