设计了一种红外三档变焦光学系统。系统工作波段为中波3.7~4.8 μm, 焦距为40/60/240 mm, 6×变倍比, 具有100%冷光阑效率, 加入2倍镜后, 焦距为80/120/480 mm。对系统进行了光学设计、传递函数分析、机械设计等分析, 带增倍镜的红外三档变焦光学系统具有像质好、变焦速度快、结构紧凑的特点, 可在红外成像系统中得到广泛应用。

A three field of view zoom system with 2×expander is designed. The focal lengthes of this zoom system at 3.7~4.8 μm are 40 mm、60 mm and 240 mm with zoom ranger of 6∶1, the f-number is 4, 100% cold efficiency. And the focal lengthes of this zoom system with 2×expander are 80 mm、120 mm and 480 mm. The optical quality, MTF and mechanical design were analyzed. The zoom system has the advantages of image quality, quick zoom switch speed and compact configuration. It can be used in the high thermal imager widely.