一种时间分辨激光诱导击穿光谱的测量方法

A Method for Time-Resolved Laser-Induced Breakdown Spectroscopy Measurement

激光诱导击穿光谱(LIBS)是一种动态光谱。时间分辨LIBS光谱测量是研究激光诱导等离子体演化和谱线自吸收的重要技术。结合激光诱导击穿光谱测量的时序特性,提出一种利用常规性能光谱探测设备获得微秒级时间分辨LIBS光谱的测量方法。通过控制毫秒级光谱探测设备的积分延迟时间,获得不同延时下的LIBS光谱信号,对所得光谱进行处理得到相应特征谱线拟合强度,将所测的特征谱线强度按照一定的时间间隔进行差分,得到差值即为差分间隔时间内特征谱线的积分强度。采用差分时间间隔应大于系统最差时序精度,同时优选无重叠干扰和背底连续的谱线信号进行分析。以等离子体产生后持续时间为横坐标,计算所得谱线差值强度为纵坐标,即可获得特征谱线的强度演化曲线。通过实验验证,使用积分时间为毫秒量级光谱仪和时序精度为0.021微秒控制系统,该方法可以实现微秒量级时间分辨LIBS光谱测量,可用于表征LIBS光谱特征谱线演化过程,降低了LIBS光谱时间分辨测量系统成本。

Laser-Induced Breakdown Spectroscopy （LIBS） is strongly time related .Time-resolved LIBS measurement is an im-portant technique for the research on laser induced plasma evolution and self-absorption of the emission lines .Concerning the temporal characteristics of LIBS spectrum ,a method is proposed in the present paper which can achieve μs-scale time-resolved LIBS measurement by using general ms-scale detector .By setting different integration delay time of the ms-scale spectrum detec-tor ,a series of spectrum are recorded .And the integration delay time interval should be longer than the worst temporal preci-sion .After baseline correction and spectrum fitting ,the intensity of the character line was obtained .Calculating this intensity with differential method at a certain time interval and then the difference value is the time-resolved line intensity .Setting the plasma duration time as X-axis and the time-resolved line intensity as Y-axis ,the evolution curve of the character line intensity can be plotted .Character line with overlap-free and smooth background should be a priority to be chosen for analysis .Using spectrometer with ms-scale integration time and a control system with temporal accuracy is 0.021 μs ,experiments carried out . The results validate that this method can be used to characterize the evolution of LIBS characteristic lines and can reduce the cost of the time-resolved LIBS measurement system .This method makes high time-resolved LIBS spectrum measurement possible with cheaper system .