大气对红外偏振成像系统的影响

Atmospheric effects on infrared polarization imaging system

红外偏振成像系统探测的是某个特定偏振方向上的目标和背景辐射强度,有必要对不同目标的偏振特性及偏振辐射大气传输进行研究。首先采用双向反射分布函数对反射辐射偏振特性进行了分析,推导出了反射辐射偏振度的一般表达式。根据表达式模拟了目标的物理特征对反射偏振特性的影响。随后利用MODTRAN软件在典型大气条件下对红外波段的大气吸收以及程辐射进行了建模和计算。大气中的悬浮颗粒对目标的红外辐射进行散射,场景的偏振度随传输距离衰减。对目标反射辐射偏振特性的仿真结果与实测数据基本吻合,验证了理论的正确性。考虑大气对偏振辐射传输的影响使得计算结果更加合理和准确。

As the infrared polarization imaging system detects the target and background radiation＇s intensity in a specific direction of polarization,it＇s necessary to study polarization properties of different objects and polarized radiation propagation in the atmosphere.Firstly,bi-directional reflectivity distribution function was used to analyze polarization properties of the reflection radiation by objects and a general expression of the degree of polarization was deduced.Through the expression,the reflection polarization properties influenced by the target′s physical characteristics was simulated.Secondly,the atmospheric absorption coefficient and path radiation in infrared waveband were modeled and calculated by using MODTRAN software in some typical atmospheric conditions.Due to the infrared radiation scattered by the suspended particles in the atmosphere,the degree of polarization of the scene was attenuated with the transmission distance.The result of simulation experiments about the polarization properties of objects′ reflection radiation coincides with the measured data well,which means that the theory is correct and robust.Considering the atmospheric effects on the transmission of polarization radiation makes calculated results more reasonable and accurate.