通过分析比较3种聚焦效果较好的清晰度评价函数，提出了一种基于聚焦窗口模式的平方梯度函数作为聚焦评价函数，建立了评价函数的数学模型，并给出了实验分析和结果。与以往常用的评价函数相比，具有更高的可靠性和聚焦灵敏度-Compared by analyzing the three kinds of focus better clarity evaluation function, a model based on the focus window as a function of the square gradient focusing evaluation function, the establishment of the evaluation function of the mathematical model, and gives the experimental analysis and results. Commonly used in previous evaluation function, compared with higher reliability and sensitivity Highlights