紫外(UV)波段是靶场光电测量的重要方式,但紫外波段目标信号弱,可选取的光学材料很少,这都为高分辨率紫外观测带来了困难。设计的用于靶场的大相对孔径长焦距紫外望远系统解决了上述问题,利用折反系统与二次成像的方法获得F数2、焦长400mm、视场1°、波段范围250~400nm的紫外光学系统。经过光学软件分析,望远系统各视场奈奎斯特频率(38lp/mm)调制传递函数(MTF)分别高于0.7。考虑到外场环境的适应性,进一步考察了望远系统在-40℃~60℃环境下的调焦量以及成像质量,分析结果表明,各温度下调焦后的奈奎斯特频率MTF均优于0.5,设计结果满足靶场设计指标与实际应用需求。
Ultraviolet(UV)spectrum is an important method for photoelectric measurement.Ultraviolet target signal is weak,only a few kinds of optical materials in this spectral range can be chosen,so it′s difficult for the highresolution ultraviolet observations.A large relative aperture and long-focus UV optical system is designed which is used in target range measurement,and it solves those problems by catadioptric imaging and reimaging.The UV optical system has the parameters of Fnumber of 2,focal length of 400 mm,field of view(FOV)of 1°,wavelength range of 250~400 nm.The Nyquist frequency(38lp/mm)modulation transfer function(MTF)is better than0.7in the telescope system FOV according to the analysis of optical software.Taking into account the environmental adaptability,focusing amount and image quality are considered at-40 ℃~60 ℃ for the UV telescope system.Result shows that the Nyquist frequency MTF is better than 0.5 after focusing which meets the design specifications and the practical application.