根据激光光线聚焦状态不同对应被测面上激光光斑形状不同的特点, 通过引入辅助激光束, 分析了调焦 CCD采集的激光光斑图像信息, 进而根据光斑形状及半径等信息确定被测面对焦状态。针对实验中每隔相同离焦距离采集的一系列光斑图像, 提出了相应的图像处理方案, 以提取所需光斑半径信息, 进而进行光斑半径与离焦量转换。实验结果表明, 光斑半径与离焦量呈线性关系, 最大线性范围灵敏度为 2.342像素 /μm, 最高可实现 0.43.μm分辨率。

As different shapes of laser spots on the measured surface correspond to different focusing states of the laser light, the auto-focus system using laser can determine defocus value of the surface by introducing auxiliary laser beam and analyzing the spot image collected by a CCD camera. To extract the required radius information from the spot images, the image processing method is proposed in this paper, and then the conversion of the spot radius and the defocus value is achieved. According to the experimental results, there is a linear relationship between the radius of the spot and the defocus value. The maximum sensitivity of the linear range is 2.342 pixel/μm, and 0.43 μm resolution is achieved.