红外光学系统的内部构件由于呈现于光路之中,其表面热辐射将会通过光学系统到达探测像面而引起背景辐射噪声。本文利用LightTools分析软件对一套折反式红外光学系统内部机械构件的主要表面的热辐射进行了分析,得到了探测像面接收到的热辐射的量级。分析了三种不同的表面反射率的情况,能够用于指导如何进行表面处理和结构设计的改善。 As the internal components of the infrared optical system appear in the optical path, the surface thermal radiation will reach the detection image plane through the optical system to cause background radiation noise. In this paper, the thermal radiation of the major surfaces of the internal mechanical components of a FTIR system is analyzed by using LightTools analysis software, and the magnitude of thermal radiation received by the image plane is obtained. Three different cases of surface reflectance were analyzed and can be used to guide how to improve the surface treatment and structural design.