中波红外光学系统无热化设计和冷反射抑制

为了得到性能好、稳定性高，能够满足民用、军事等领域应用的中波红外成像光学系统，采用光学被动式的无热化技术，在常温下像质良好的初始结构基础上，通过对不同红外材料组合，实现系统的无热化设计。利用等效温差(NITD)计算冷反射贡献量，对冷反射贡献量较大表面的曲率和光焦度进行优化。设计结果表明:在-40℃~60℃温度范围内，光学系统的MTF在30 lp/mm处均大于0.5；离焦量在一倍焦深以内，点列图(RMS)直径小于像元尺寸；冷反射残存量最大的表面NITD值降低40%。应用该方法可以很好地实现红外成像光学系统的无热化设计，对冷反射的抑制效果明显。

Athermalization and suppression of narcissus for medium-wave infrared optical system

Infrared optical system is the core component of infrared imaging devices. Athermalization is widely adopted in mid-infrared optical design in order to improve performance and stability of infrared imaging optical systems, and meet performance requirements of civil and military applications. In this paper, passive athermalization design of a non-thermal mid-infrared imaging optical system is realized through combining different infrared materials. Contribution of narcissus is calculated by NITD method, curvature and optical power of surface with large contribution to narcissus are optimized. Results show that MTF of optical system is greater than 0.5 at 30 lp/mm in temperature range of -40 ℃ ~ 60 ℃, defocus distance is less than depth of light, RMS diameter is less than pixel size. Maximum NITD value of narcissus is reduced by 40%, which is smaller than minimum resolution temperature difference of the system. Application of this method can be very good to achieve athermalization design of infrared imaging optics system, and suppression effect of narcissus is obvious.