Product Code: ICA12_N102

Opto-Hydrodynamic Processing of Materials Using Microdroplets - Invited Presentation - 30 Minutes
Authors:
Daehwan Ahn, Department of Mechanical Engineering, POSTECH; -
Changho Seo, Department of Mechanical Engineering, POSTECH; -
Dongsik Kim, Department of Mechanical Engineering, POSTECH; Pohang South Korea
Presented at ICALEO 2012

A novel surface processing technique entitled Droplet Opto-hydrodynamic Processing (DOP) technique is introduced [1]. The process is based on the laser-induced breakdown (LIB) of a micro liquid droplet and subsequent ejection of a high-speed micro liquid jet. The speed of the microjet (~1300 m/s) is sufficiently high to remove nanoscale particles or thin films from solid surfaces and remove a variety of materials with substantially large ablation rates. In particular, the combined effect of the hydrodynamic impact of the jet and the transmitted (refocused) laser pulse can fabricate high-aspect-ratio microstructures and eliminate thin oxide films with negligible thermal effects. Furthermore, the small volume of the liquid droplet (<<1 microliter per pulse) enables precise and selective processing of surfaces. In this work, the hydrodynamics of the micro liquid jet induced by LIB of free-falling or capillary-trapped droplets is analyzed using a Q-switched Nd:YAG laser. The results of DOP of metals, ceramics, and hard/soft biological tissues are presented with discussions on the material removal mechanisms. The results are also compared with those by a Ti:Sapphire femtosecond laser.