介绍了红外系统中自动调焦技术的基本原理，详细分析了调焦组件的机械回程间隙对传统自动调焦算法效果的影响。就此提出了不同优化方案并充分考虑了算法的适用性及稳定性。最后，通过设计实验验证了算法的可行性，实现了快速、稳定、精确的自动对焦，并将其应用于工程实践中。

This paper introduces the basic principle of auto-focus technology in infrared systems, and analyzes in detail the influence of focusing mechanism backlash on the traditional auto-focus algorithm. A variety of optimized schemes are proposed， and the applicability and stability are fully considered. Finally, an experiment is designed to verify the feasibility of the algorithm which realizes fast, stable and accurate auto-focus， and the algorithm can be used in engineering practice.