飞秒激光光斑灰度与几何特征的相关性分析

飞秒激光烧蚀单晶硅的加工过程中，CCD相机采集的光斑图像中有效灰度区域与背景难以区分。为了解决这一问题，提出一种主成分分析与限制对比度自适应直方图均衡化相结合的方法，对光斑图像进行增强处理，再提出去趋势互相关分析法对光斑序列图像的灰度特征与几何特征进行长程相关性分析。结果表明，光斑序列图像的灰度特征与光斑纹理对比度、光斑面积具有较强的长程相关性，与纹理同质性表现出较强的反相关关系，可根据这3项与灰度特征较强的相关关系对后续微槽加工过程中的灰度特征进行预测。

Correlation analysis of gray scale and geometric features of femtosecond laser spot

During the processing of femtosecond laser ablation of monocrystalline silicon, the effective gray area in the spot image collected by the charge coupled-device (CCD) camera was difficult to distinguish with the background. In order to solve this problem, a method combining the principal component analysis with the adaptive histogram equalization of limited contrast was proposed to enhance the spot image, and then a detrending cross-correlation analysis method was proposed, which analyzed the long-range correlation of gray features and geometric features for the spot sequence images. The results show that the gray features of the spot sequence images have a strong long-range correlation with the spot texture contrast and the spot area, and they show a strong inverse correlation with the texture homogeneity. The correlation relationships are used to predict the gray features in the subsequent micro-groove processing.