雜散光為光學系統中不需要或是額外衍生出來的光線，雜散光的出會降低對比、影像品質，嚴重者對致系統或是任務失敗，因此抑制雜散光是相當重要的課題。雖然無法完全使雜散光消失，但是適當的光機設計(opto-mechanical design)將可以有效的抑制雜散光在合理的程度內。本文將討論雜散光的成因、雜散光抑制的基本概念、雜散光分析的方法以及在實務上的應用。

Stray light are the unwanted light in optical system, it will reduce contrast or image quality. Sometimes, it will cause the mission fails. The stray light in optical system is always being there, but we can control the stray light in a reasonable order by a suitable opto-mechanical design. This article presents some basic concepts of stray light, the analysis of stray light suppression, and an analysis result of real case.