杂散光是影响光学系统成像质量的重要因素之一，因此对杂散光的分析与抑制成为现代红外光学系统设计过程中的一个重要环节。根据杂散光抑制要求，确定了天基红外成像光学系统的结构形式；分析了系统存在的杂散光源，计算了系统点源透过率(PST)须满足的条件；设计并分析了遮光罩、挡光环、遮光板、光阑和消杂散光材料等杂散光抑制方法；在杂散光分析软件TracePro 中建立系统模型，分别对系统内部及外部杂散光进行分析，计算并绘制了PST 曲线。结果表明，系统内部杂散光为1.53×10-3 W/m2，系统外部杂散光PST 曲线整体为下降趋势，PST 在离轴角度为±3°时达到10-3～10-5，系统对杂散光的抑制能力完全满足成像质量要求。

Stray light is one of the most important factors that affect the image quality of optical system, thus the analysis and suppression of the stray light becomes a significant part in the design processes of the modern infrared optical system. According to the requirements of stray light, the configuration of the space-borne infrared optical system is determined; the sources of the stray light is analyzed, and then point source transmittance (PST) is taken as the standard to evaluate the analysis; the methods of the stray light suppression are designed, such as baffle, vanes, occulters, stops and material; the model of the system is established and its stray light is analyzed with TracePro, and then the PST curves of the system are calculated. The results indicate that the thermal emission of the system is 1.53×10-3 W/m2; the PST curves of the system are declining, at off-field angle ±3°, the PST of the system arrives at 10-3~10-5, stray light suppression of the system satisfies the requirements of the image quality.