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自动调焦技术是提高显微镜测量精度的重要手段，本文介绍了采用图像处理法实现显微镜自动调焦的方法。对图像处理法实现显微镜自动调焦中的两个关键技术进行了详细的讨论：其一是图像清晰度评价函数的选取，文中采用绝对方差函数和修正平方梯度函数分别作为粗精调焦评价函数；另外还针对提高图像信息质量的方法进行了探讨，采用线性拟合与同态滤波方法进行图像处理，为离焦判断提供高质量的图像信号。实验表明，该方法调焦精度达±０．３μｍ 。
Automatic focusing technology is an important means to improve the measurement accuracy of microscope. This paper introduces the method of using microscope to realize the automatic focusing of the microscope. The two key technologies of image processing method to realize automatic focusing in microscope are discussed in detail. The first one is the selection of the image sharpness evaluation function. In this paper, the absolute variance function and the modified square gradient function are respectively used as the rough fine focusing evaluation function In addition, the methods of improving the quality of image information are also discussed. The linear fitting and homomorphic filtering are used to process the image and provide high quality image signal for defocus judgment. Experiments show that the method of focusing accuracy of ± 0.3μm.