针对硫系玻璃材料热稳定性高、光谱透射率好、适合模压成型等特点，提出一种采用硫系玻璃的长波红外光学系统设计方法。理论分析了被动式光学补偿和机械补偿的设计过程。根据被动光学补偿原理求解系统初始光焦度分配，借助被动机械补偿方法设计了一种大相对孔径红外消热差光机系统。系统焦距为90 mm，F 数为0.9，适配长波(8~14 μm)非制冷红外焦平面探测器，其像素为640 pixel×512 pixel，像素大小为17 μm。在-40 ℃~50 ℃温度范围内工作时，系统各视场调制传递函数(MTF)均接近衍射极限。设计结果表明，利用硫系玻璃相互匹配并结合机械补偿方法可以实现系统被动无热化，能够得到性价比较高的红外成像光学系统。

According to the characteristics of chalcogenide glass with high thermal stability, perfect spectrum transmittance and moldable property, a design method for long-wave infrared optical systems only with chalcogenide glasses is proposed. The design process of passive optical athermalization and passive mechanical athermalization is analyzed. The initial optical power contribution is calculated based on the theory of passive optical athermalization. An infrared athermalized optical system is designed. The focal length is 90 mm, the Fnumber is 0.9. This system is compatible with uncooled long-wave infrared (8~14 μm) focal plane array which has a format of 640 pixel × 512 pixel and a pixel pitch of 17 μm. It can adapt within the temperature range of -40 ℃~50 ℃ , the modulation transfer function (MTF) of full field of view is close to the diffraction limit through the entire temperature range. The results show that the passive athermalization can be realized by matching chalcogenide glasses and using passive mechanical compensation, and the low-cost infrared imaging optical system can be achieved.