采用激光诱导击穿光谱分析技术对钢样中锰、 铬两种微量元素的含量进行了测量。 实验研究发现， 最优取样的延迟时间为2.0 μs， 最佳激光光束聚焦位置和光谱收集探头分别位于样品表面以下3.5 mm和表面以上1.5 mm处。 以Mn Ⅰ: 403.07 nm和Cr Ⅰ: 427.48 nm作为分析线， 分别采用传统定量分析和内定标的方法对钢样中的Mn和Cr进行了定量分析。 通过对比发现， 采用内定标方法得到的拟合曲线的相关指数R2分别为0.998和0.979， 均高于传统定标方法拟合曲线的相应相关指数。 利用内定标建立起来的定标曲线， 计算得到Mn和Cr的检测限分别是0.005%和0.0406%。

Quantitative analysis of trace elements such as manganese and chromium in steel was performed employing laser-induced breakdown spectroscopy (LIBS) technique in the present paper. The experimental measurements indicate that the optimal delay, focal plane and detecting position from the sample surface are 2 μs, -3.5 mm and 1.5 mm，respectively. Mn Ⅰ: 403.07 nm and Cr Ⅰ: 427.48 nm were selected as the analytical lines and their contents in the target steel sample were analyzed with traditional quantitative analysis and internal standard methods. Comparison of the results with two kinds of quantitatively analytical methods show that the coefficients of determination gained by internal standard method are 0.998 and 0.979 which are much better than the results obtained by traditional quantitative analysis method. According to the established calibration curve by internal standard method the detection limits of manganese and chromium calculated are 0.005% and 0.040 6%, respectively.