将基于图像清晰度评价函数的自动聚焦算法应用于共线双脉冲激光诱导击穿光谱(DP-LIBS),基于LabVIEW编写的控制软件对共线DP-LIBS实验系统与CCD相机、三维移动平台进行有效控制,将图像清晰度评价、自动聚焦算法和三维移动平台相结合,实现了样品的自动聚焦功能。实验结果表明:两激光脉冲间隔的最优位置为0.55 μs;原子谱线的稳定性高于离子谱线;采用自动聚焦系统后,光谱强度的相对标准偏差(RSD)从16.7%降低到6.7%,钢样中Cr元素和Mn元素定量分析的相关系数分别从0.851和0.639提高到0.947和0.923。自动聚焦系统能够提高信号的稳定性和测量精度。

In this paper, we apply the auto-focusing algorithm, which is based on the image sharpness evaluation function, to collinear double pulse laser-induced breakdown spectroscopy (DP-LIBS). Through the control software based on LabVIEW, the collinear DP-LIBS experiment system, CCD camera and three-dimensional mobile platform are effectively controlled. Image sharpness evaluation, the auto-focusing algorithm, and the three-dimensional mobile platform are combined to achieve sample auto-focusing function. The results show that the optimal interval between the two lasers is 0.55 μs. The stability of the atomic spectral line is higher than that of the ion line. The relative standard deviation of the spectral strength decreases from 16.7% to 6.7%. The quantitative analysis of the steel samples shows that the correlation coefficients of Cr and Mn measurements increase from 0.851 and 0.639 to 0.947 and 0.923, respectively. Overall, the auto-focusing system can improve signal stability and measurement accuracy.