针对目前已有的基于端面图像的熊猫保偏光纤定轴系统中多采用手动对焦的问题，搭建一套自动对焦系统，提出一种基于保偏光纤定轴系统成像特点的自动对焦算法。该算法选择方差函数进行对焦评价，同时采用基于局部方差最大的对焦窗口选择方式来提高灵敏度，使用一种基于迭代拟合的综合搜索策略来搜索焦点。实验表明，本算法能够实现对保偏光纤端面及其衬块的快速稳定对焦。

Since the PMF’s polarization axis alignment method based on image processing of PMF’s end, has been researched and applied more and more, manual focus predominates in the image-processing alignment system. Consequently, an autofocus system is built, and an autofocus algorithm based on the imaging characteristic of alignment system is presented. The variance function is selected to evaluate image definition, with a focusing window selection method based on local variance maximum to enhance its sensitivity. Additionally, a comprehensive strategy based on iterative fitting is designed to search for image focus. The experiment results indicate that this algorithm can realize the focusing of PMF and its gasket both fast and stably.