气动热辐射效应导致红外探测制导系统的性能降低甚至失效，而红外窗口是气动热辐射效应评估的关键因素。通过分析红外辐射在红外窗口中的传输特性，提出一种红外窗口气动热辐射效应评估方法，基于等温状态试验，评估了某超音速飞行器红外探测系统蓝宝石红外窗口在中波3.7~4.8 μm波段的气动热辐射效应。研究结果显示，红外窗口暴露于大气环境后，蓝宝石窗口导致的气动热辐射效应迅速上升，表现为红外窗口透过率下降约10%，仍然在0.9以上，而自辐射迅速增强约458倍，相当于约125 ℃黑体，在探测器获取总辐射中的比例大于78%。在对地探测应用中，对于厚度小于20 mm的蓝宝石红外窗口，窗口温度在100~350 ℃范围内，随着厚度增加，透过率下降，自辐射增强，总辐射也增强，自辐射在总辐射中的比例增加，易造成探测器饱和，对探测系统影响较大。

The windows of IR detection systems becomes the main factor of the aero-thermo-radiation effect, which reduces the performance of these IR systems, or even makes these systems fail. By analyzing thermal radiation propagating in IR windows, a participating medium, an evaluation method for aero-thermo-radiation effect of the non-isothermal IR windows was proposed, based on the experimental results of the isothermal state, include self-radiation and transmittance. Aim to an MWIR detection system of a hypersonic vehicle, aero-thermo-radiation effect of a sapphire IR window was evaluated in 3.7-4.8 μm. The results indicate that, as the sapphire IR window is exposed in high-temperature and high-speed airflow, the aero-thermo-radiation effect of the window intensifies as temperature rises rapidly, the transmittance drops about 10%, still bigger than 0.9, otherwise the self-radiation enhances 458 times approximately, equal to that of blackbody about 125 ℃. For sapphire windows in 100-350 ℃, which thickness are smaller than 20 mm, as thickness increases, the transmittance decreases, self-radiation increases, and total radiation behind sapphire windows is increased, of which the ratio of self-radiation increases. So, self-radiation would drive detector into saturation easily, of which the influence on the MWIR detection system is bigger than that of transmittance.