红外辐射测量系统内部杂散辐射建模与仿真

Modeling and Simulation of Internal Stray Radiation of Infrared Radiometer Based on Compound Monte Carlo Method

杂散辐射是影响光学系统性能的重要因素,对于红外光学系统,除了外部杂散辐射,还须考虑系统自身结构产生的内部杂散辐射。为提高红外辐射计内部杂散辐射分析的精度,建立了1种基于复合蒙特卡洛法的内部杂散辐射数学模型。首先,将红外辐射计的内部杂散辐射源根据位置分为2部分:遮光罩入瞳处的热辐射和辐射计内部光学元件、机械部分所发出的热辐射。对于遮光罩入瞳处和辐射计内部光机元件发出的杂散辐射,分别采用正向蒙特卡洛法和反向蒙特卡洛法进行追踪,得到探测器接收面入瞳处的杂散辐射辐照度分布,进而分析不同位置的发射源对接收面入瞳处的杂散辐射贡献。最后,与直接模拟仿真结果进行对比。实验结果表明,在追迹光线数相等的情况下,该方法的精度更高。仿真结果体现了红外辐射计各部分杂散辐射对探测器入瞳面接收到的杂散辐射造成的影响,对后期开展内部杂散辐射抑制提供了方向。

Stray radiation is an important factor affecting the performance of optical systems.For infrared optical systems,in addition to external stray radiation,it is also necessary to consider the internal stray radiation generated by the structure of system.To improve the accuracy of internal stray radiation analysis of infrared radiometer,a simulation method of internal stray radiation based on the compound Monte Carlo method is proposed.Firstly,the internal stray radiation source of the infrared radiometer is classified into two parts according to the location:stray radiation at the pupil of the hood and stray radiation emitted by the internal optical element and the mechanical part of the radiometer.According to the location characteristics of the emission point,the forward Monte Carlo method is used for the pupil of the hood,and the reverse Monte Carlo method is used for the internal optical and mechanical elements of the radiometer to track the stray radiation.The distribution of stray radiation irradiance at the pupil of the receiving surface of the detector is obtained,and then the contribution of stray radiation at the pupil of the receiving surface from the emitting sources at different locations is analyzed.Finally,compared with the direct simulation results,the experimental results show that the accuracy of the method is higher when the number of tracing lines is similar.The simulation results based on the composite Monte Carlo method of internal stray radiation analysis reflect the influence of each part of the infrared radiometer on the stray radiation received at the pupil entry surface and provide a direction for the later work on internal stray radiation suppression.