10倍中波红外连续变焦光学系统设计

Design of 10× MWIR Continuous Zoom Optical System

针对制冷型320 pixel×240pixel凝视焦平面阵列探测器，设计了一款10倍中波红外连续变焦光学系统。系统采用机械正组补偿变焦结构，通过二次成像设计实现系统10096的冷光阑效率，利用硅和锗两种普通红外光学材料，通过引入合理的非球面和衍射面，借助ZEMAX光学设计软件对系统进行优化设计和像差平衡，实现了20-200mm的中波红外连续变焦系统的优化设计。设计结果表明：系统仅采用7片镜片，实现了变倍比为10、F数为2、工作波段为3．7～4．8um的中波红外连续变焦系统的优化设计，系统的调制传递函数在空间频率16lp／mm处大于0．4，点斑均方根半径均小于16um，接近衍射极限，满足系统成像要求，且系统的变焦曲线平滑，符合变焦要求。

A 10 × mid-wavelength infrared （MWIR） continuous zoom optical system is designed for cooled 320 pixel × 240 pixel staring focal plane array detector. The system uses mechanical positive compensation zoom system. 100% cold stop efficiency is realized by secondary imaging system. Two common infrared optical materials, i.e., silicon and germanium, are used. By introducing reasonable aspheric and diffractive surfaces, the aberrations are balanced. By using ZEMAX optical design software, the system is optimized for continuous zoom is the range of 20-200 mm. After design and optimization, the system only uses 7 lenses to realize 10x continuous zoom. The F number is 2, the working wavelength is 3.7-4.8 um, the modulation transfer function （MTF） at spatial frequency of 16 lp/mm is larger than 0.4, and the root mean square （RMS） radius is smaller than 16 um. It has a resolution close to diffraction limit and satisfies the requirement of imaging. Moreover, the system has a smooth curve zoom and meets the zoom reauirement.