折反式微光夜视物镜的光学设计

介绍一种长焦距、大相对孔径微光夜视物镜的光学设计。设计参数为焦距100 mm，相对孔径1/1.4，视场10。为增大视距，减小物镜尺寸和质量，并且满足在宽光谱范围消色差的要求，选择均为球面的折反式物镜结构，在相同焦距和相对孔径的条件下折反式系统比折射系统尺寸更小，质量更轻。在设计过程中引入曼金反射镜，增加设计自由度。经优化设计达到较好的成像质量，空间频率在50 lp/mm时，轴上传递函数大于0.4，轴外传递函数大于0.2，与像增强器极限分辨率相匹配，全视场畸变小于2 %，物镜总长达到67 mm。

Optical design of catadioptric LLL night vision objective

A design of low-light-level(LLL) night vision objective with long focal length and high relative aperture is introduced. The design parameters are as follows: the effective focal length is 100mm, the F-number is 1.4 and the field of view is 10°.To improve the visual range, reduce the size and weight of the objective and get achromatic result in wide spectral range, the all-spherical catadioptric structure is selected. Catadioptric system is considerably shorter and lighter than the refractive lens with the same focal length and F-number. The Mangin mirror is introduced into the design, which gives the optical system extra degrees of freedom without adding another element. By optimizing the aberrations, good image quality of the objective is obtained. At the spatial frequency of 50lp/mm, the on-axis modulation transfer function (MTF) of the objective is not less than 0.4 and the off-axis MTF is not less than 0.2, which match with the limiting resolution of image intensifier. The distortion of objective is less than 2% in full field of view, and the total length of objective is 68mm.