利用自行设计的集成微区成像激光诱导击穿光谱系统, 分析了孔径光阑设定、目标区域大小以及样品表面反射率对表面图像位置敏感特性的影响.结果表明, 表面图像锐度在大孔径设定下对位置更为敏感, 适用于自动对焦过程; 反射率对表面图像锐度的位置敏感特性影响较小, 且部分表面图像的锐度也可用于辅助激光诱导击穿光谱对焦; 不同样品不同目标区域大小, 图像锐度最大值对应表面位置具有很好的重复性.在此基础上, 建立了基于表面图像锐度的自动对焦方法.

By using a homemade laser induced breakdown spectroscopy system integrated with a micro-imager, the influence of aperture, region of interest, reflectivity of sample on position sensitivity of image acutance was analyzed. The results show that image acutance is more sensitive to the position under larger aperture, larger aperture is more suitable for the autofocus process. The reflectivity of sample has a little influence on the position sensitivity of image acutance, and the acutance of the partial image can also be used to assist the laser induced breakdown spectroscopy focus. The surface position corresponding to the maximum acutance has good repeatability for different samples and different region of interest. On this basis, an autofocus method based on the acutance of the surface image was established.