Hole Formation Process in Ultrashort Pulse Laser Percussion Drilling

We performed an in-situ analysis of the percussion drilling process with ultrashort laser pulses in silicon, which acts as a model system for drilling opaque materials like metals. The investigations are focused on three parts: (1) the role of redeposition of ablation particles inside the hole which can be reduced by reduction of the ambient pressure and results in an increased achievable depth, (2) the influence of the repetition rate to analyze the heat accumulation effect, which increases the achievable depth despite a possible particle shielding, and (3) the effect and evolution of the laser generated plasma.