一种时间分辨激光诱导击穿光谱的测量方法

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。

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

Laser-Induced Breakdown Spectroscopy (LIBS) is strongly time related. Time-resolved LIBS measurement is an important 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 detector, a series of spectrum are recorded. And the integration delay time interval should be longer than the worst temporal precision. 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.