基于液晶可调滤光片(Liquid Crystal Tunable Filter, LCTF)的分光原理, 设计一种工作谱段为400~720 nm, 焦距4.5 mm, 视场角140°, F数为1.28的广角多光谱成像光学系统。该光学系统由前端光学镜头、LCTF和成像镜头组成, 其中前端光学系统镜头将入射光束进行扩束, 同时将入射光束的广角视场缩小至LCTF可接收角度范围内; LCTF利用液晶材料的电控双折射效应, 实现对某一波长光信号的选择透过。根据多光谱成像系统的总体方案, 对光学系统的各光学参数进行合理选取。设计结果表明, 整个系统在120 lp/mm的空间频率处轴上及轴外的调制传递函数MTF均大于0.4。

Based on the spectrum dividing principle of liquid crystal tunable filter, the optical system of wide-field multispectral imaging spectrometers is designed, which has the range of spectral band 400~720 nm, the focal length of 4.5 mm, field of view of 140°, F number of 1.28. The system is composed of the first part of the lens, LCTF and the imaging lens. The wide-angle view of the incident light beam is converted by the first part of the lens into width beam, the divergence angle of which is less than the acceptance angle of the filter, the tuning of the broad band is achieved by using the electro-birefringence effect of liquid crystal. On the basis of instrument and system consideration, the optical parameters are distributed reasonably. The results show the modulation transfer function of the whole system at 120 lp/mm is larger than 0.4 in the full filed of view.