大相对孔径红外变焦距光学系统设计

Design of LWFIR Zoom Optical System with Large Relative Aperture

设计了工作在8～12μm波段的非致冷红外连续变焦光学系统。该系统由4组元5片透镜组成,其中前固定组、变倍组和补偿组均只有1片透镜,后固定组为两片。焦距50～200mm,相对孔径较大,为1∶1。设计过程中编写了适用于二组元变焦系统的ZEMAX宏程序,该程序可给出凸轮曲线的数据和形状,同时使像面位置不受限于高斯光学关系,能够满足某些焦距位置离焦的要求。系统在空间频率为20lp/mm处,各个视场的MTF值均在0.4以上。

A high-speed uncooled infrared zoom optical system in the spectrum 8-12μm region is designed.The system is a simple structure with four parts and five pieces lens; the rear fixed unit is composed of two lenses, the rest are only one lens.The effective focal length ranges from 50mm to 200mm.The relative aperture is 1∶1. The zoom cam curve shape and data are given by zpl which is can be applied to two-ariable-unit zoom system, in this way the re-quirement of defocus was satisfied at some focal length.Image quality evaluation result shows that the MTF is higher than 0.4 in all field of view at the spatial frequency 20 lp/mm.