Visualization of particle trajectories in the laser shock cleaning process

The laser shock cleaning (LSC) method has recently attracted substantial attention since it can remove micro/nano-scale contaminant particles from a solid surface without direct exposure of the surface to laser irradiation. However, despite the importance of the particle detachment and redeposition mechanisms in the LSC process, the behavior of the particles during the cleaning process has never been analyzed experimentally. In this work, the motion of the micrometer-scale particles detached by a laser-induced plasma/shock wave is visualized by a photoluminescence imaging technique. The technique yields time-resolved particle trajectories under typical conditions of the LSC process, with and without a gas jet blowing. Discussions are made on the behavior of the detached particles and redeposition mechanisms.