Effects of multiple-pulse iradiation in ultra-fast pulse laser processing studied through a newly developed visualization technique

我们开发了一种新的、高时间分辨率的高速视频系统，用于可视化超快脉冲激光加工中的多脉冲辐照效应。该技术被称为高速激光频闪摄像技术，已成功地应用于观察飞秒激光在硬质合金样品上打槽和打孔过程中的激光诱导现象。分析了激光脉冲能量和扫描速度对加工后熔体的发展和碎屑沉积的影响。实验结果表明，这些效应相当复杂，需要进一步的系统研究。该技术已成功地应用于液体中激光烧蚀的动力学研究。分析了激光诱导空化气泡对激光冲击过程的影响。利用该技术研究了液体中激光烧蚀产生纳米粒子的过程。

We have developed a new, high-speed video system with high time-resolution for visualizing multiple-pulse irradiation effects in ultra-fast pulse laser processing. The technique, named as high-speed laser stroboscopic videography technique, has successfully applied to observe the laser-induced phenomena during a groove and a hole drilling by a femtosecond laser on cemented tungsten carbide samples. Effects of laser pulse energy and scan speed on developments of machined futures and deposition of debris were analysed. Observed results indicate that these effects were rather complicated and demand further systematic researchs.The developed tehcnique has been successfully applied in dynamical studies on laser ablation in liquids. Effects of laser-induced cavitation bubbles on laser shock processes have been analysed. Nano-particle generation by laser ablation in liquids have been studied through the technique.