在航空遥感领域中，自动调焦技术是获取高质量图像的关键技术之一，且在一定范围内得到了应用，但其实时性能较差。为解决调焦耗时长的问题，提出以连续三帧重叠区域图像为指导的自动调焦算法。简述了由电荷耦合器件(CCD)相机、调焦机构和调焦电路板等组成的自动调焦系统；自动调焦控制算法对快速提取重叠区域和帧差值相似判定法进行了综合，针对重叠图像利用聚焦评价函数实现了由大步长快速粗调到小步长精确细调，从而不断逼近正焦位置；利用聚焦函数的聚焦值给出自动调焦系统的软件设计流程；试飞试验表明上述算法在满足自动调焦基础上能够获取清晰图像，同时大大降低图像的分析量，提高系统响应速度。

In aerial remote sensing field, auto-focus is one of the key problems to get high-quality images and applied to the certain fields, but real-time performance is poor. To improve calculating speed, the pixel-by-pixel overlapped sections in the three of frame images are selected as the gist for auto-focus algorithm. The auto-focus system consists of charge coupled device (CCD) camera, focusing mechanism, hardware circuit and so on. The new auto-focus algorithm combines captured overlapped areas and estimated similar frame difference method to search overlapped sections. In the overlapped sections, selecting the focusing evaluation function and step length realizes the transition from fast rough adjustment to accurate one and reaches the best state. The design of the software flowchart is given by using the focus value. The real flying experiment demonstrates that the auto-focus system improves the quality of image and the time of respond speed and minishes the burden of image processing software.