针对激光诱导击穿光谱(LIBS)研究对时间分辨动态光谱测量方法的需求, 建立了基于多通道光纤束的动态LIBS测量方法。 该方法首先利用不同长度的光纤组成多通道光纤束, 对瞬态LIBS信号进行差异延迟, 使按照特定时间序列发射的光谱信号同步到达探测器, 而后采用面阵ICCD相机对同步到达的多通道光谱信号进行高时间分辨探测。 该方法单次测量即可获得LIBS辐射不同时刻的时间分辨光谱。 为了验证基于多通道光纤束的动态LIBS测量方法, 研制了具有19个通道的光纤束, 光纤束中包含的各个单根光纤长度呈等差数列排布, 长度差设置为10 m, 对应测量的时间间隔约为50 ns, 单次测量记录的总时间长度近900 ns。 分别基于短脉冲激光光源和标准光源, 开展了系统时间响应和光谱响应特性研究, 获得了系统的时间响应数据和光谱响应曲线。 用YAG激光器的二倍频激光(532 nm)诱导Si产生等离子体辐射光谱, 在线测量了辐射光谱的时间演化历程, 获得了Si等离子体辐射过程中Si Ⅰ 390. 52 nm, Si Ⅱ 385. 51 nm, Si Ⅱ 413. 12 nm谱线从0~898 ns时间范围内19个时刻的光谱信息, 获得了特征光谱的演化规律, 验证了该测量方法的可行性。 结果表明, 利用该测量方法, 单次测量可以获得瞬态LIBS辐射过程中19个时刻的光谱参数, 具有很高的测量效率。 对于实验成本较高、 运行频率低的激光诱导等离子体实验研究, 采用该方法可以大大降低了测量成本, 有效提升等离子体时间分辨动态光谱测量能力。

Time-resolved measurement of laser-induced breakdown spectrum (LIBS) is valuable in many applications. However, it is of high technical challenges. Thus, a new LIBS method based on multiple channel fiber bundle is developed. In this method, a fiber bundle consisting of many fibers with different lengths was first used to delay the signal of LIBS. Then, the spectra from different channels were recorded by an intensified charge-coupled device (ICCD) in different areas. For demonstration, a fiber bundle with 19 channels was constructed. The length of the fiber was in an arrangement of arithmetic sequence with a difference of 10m, corresponding to an interval time of 50 ns. The full recording length was 0.9 μs. The system was used to measure the breakdown spectrum of Si. The results showed multiple spectrum lines at 390.52 nm (Si Ⅰ), 385.51 nm (Si Ⅱ), and 413.12 nm(Si Ⅱ) at 19 moments of 898 ns, which clearly exhibited the dynamic development of the breakdown spectrum. This new method can acquire the spectra at different moments in a single measurement. Therefore, it has a very high measurement efficiency. In particular, for experiments with expensive costsor low operation frequencies, this method could reduce the cost, efficiently increasing the ability of time-resolved spectrum measurement.