The Plasma-Side Wall Interactions During Femtosecond Laser Drilling of High-Aspect-Ratio Microholes

The drilling of high-aspect-ratio microholes has very important applications in automotive, aerospace, electronics and other areas. However, this is difficult to realize with conventional mechanical machining or electrical discharge machining approaches. Femtosecond laser ablation can potentially provide a good solution to this, but it also involves many technical difficulties. One of these is that the laser-induced plasma, as it expands out of the microhole, may transfer its energy to the side wall of the hole, which may affect the hole size and geometry. In this paper, the plasma – side wall interaction has been studied using a physics-based model, and the discovered characteristics of the interaction are discussed.