由于红外具有能识别伪装、可昼夜工作和被动工作的优势而被广泛地应用于跟踪和搜索系统.而这些系统要求红外光学系统成像清晰、结构紧凑、可适应较大的温度变化.依据光学被动消热差的方法设计了可在较宽温度范围工作、成像质量优良、结构紧凑、体积小的红外中波摄远物镜,其摄远比可达到0.6.系统参数如下:工作波段为3~5 ?m,焦距150mm,F 数为3,工作温度为－40℃~60℃.设计结果显示,该系统仅采用3 片透镜并利用衍射元件消热差完成了无热化的要求,减少了系统的成本及重量,传递函数在17 lp/mm 处均在0.8 以上,与衍射极限十分接近,满足在宽温度范围内工作成像质量高及系统小型化的要求.

Infrared system has many advantages,such as recognizing camouflage,working all day,passive work and so on,so it is widely used in tracking and searching systems.However,these systems require that the infrared optical system has clear image,compact structure and can adapt to large temperature variations.According to the optical passive athermalized methods,a mid-wave infrared telephoto lens is designed.It can work in a wide temperature range,has excellent image quality,compact structure,and small volume.The telephoto ratio can reach 0.6.The parameters of system are as follows:working band is 3-5 ?m,focal length is 150mm,F number is 3,and the working temperature is －40℃-60℃.The results show that the system only uses three lenses and diffractive elements to achieve athermalization requirements.It reduces cost and weight of the system,modulation transfer function is above 0.8 at 17 lp/mm and close to the diffraction limit.It achieves the requirements that have excellent image quality over a wide temperature range and miniaturization.