高超声速飞行器在飞行过程中受到强烈的气动加热，位于头部的红外探测窗口温度上升显著，辐射透过率下降的同时自身发射辐射大幅增强，致使内部的红外探测器信噪比下降，严重情况下可能失效。对超声速弹头弹道末端蓝宝石红外探测窗口的气动加热-非稳态温升过程及其3.7-4.8 μm波段红外辐射透射特性进行数值模拟，结果表明：平均温度已经不能准确反映蓝宝石窗口的红外透射特性及其对红外探测器灵敏度的影响；存在一个最优的红外探测窗口厚度，该厚度下红外探测器在弹道末端的灵敏度达到最佳。

The hypersonic vehicle is subjected to intense aerodynamic heating during flight. The temperature of the sapphire infrared radiation (IR) window located in the head rises significantly, and the transmittance decreases while the self-radiation is greatly enhanced, resulting in a decrease in the internal infrared detection gas signal-to-noise ratio. The aero-heating with unsteady temperature rise process of the sapphire IR window and the infrared radiation transmission characteristics of the 3.7-4.8 μm band were numerically simulated. The results show that the average temperature can't accurately reflect the infrared transmission characteristics of the sapphire IR window and its impact on the sensitivity of the infrared detector. There is an optimal infrared detection window thickness in which the sensitivity of the infrared detector reaches best.