天基红外探测系统的杂散光分析与计算

Analysis and Calculation of Space-Based Infrared Detecting System

探讨了天基红外探测系统的杂散光来源,运用黑体辐射的理论分别对其大小进行了分析和计算。分析地气杂光在探测器靶面的辐照度时,通过在仿真软件中建立模型,应用追迹光线的方法得到了地气表面对相机所张的立体角,从而求出地气杂光在探测相机靶面上的辐照度,减小了计算的复杂度。然后对探测系统的噪声进行了分析,计算了某一个型号Sofradir焦平面器件的噪声等效辐照度(NEI),通过比较发现,杂散光在探测器靶面的辐照度远大于热像仪的NEI,必须对杂散光采取抑制措施。最后对地气杂光的抑制比和光学系统的致冷温度要求进行了分析,结论为系统的设计提供了参考。

The sources of stray sight of space-based infrared detecting system are studied.They are analyzed and calcuated by use of blackboby radiation.The irradiance of the focal plane which arises from earth and atmosphere is analyzed by model established in TracePro.The projected solid angle subtended by the surface of earth and atmosphere to the camera can be known by the method of ray-tracing.The method makes the complex calculation become easy.Then the noises of detecting system are analyzed.The noise-equivalent-irradiance（NEI） of a certain Sofradir infrared-focal-plane-array is calculated and compared with irradiance induced by other stray lights.The result proved that the irradiance of the focal plane which arises from stray light is far bigger than the NEI of the infraredfocal -plane-array.Methods should be adopted to suppress stray light.The demand of rejection of the stray light from earth and atmosphere and the demand of the temperature of optical system are given.This result can be a reference for system design.