Influence of Pulse Bursts on the Specific Removal Rate for Ultra-Fast Pulsed laser Micromachining of Copper.

Compared to single pulses the utilization of pulse bursts on steel samples was reported to be more efficient. But with regards to the specific removal rate it can be shown that a maximum value is achieved when the applied peak fluence equals exp(2) times the threshold fluence. The higher reported efficiency is caused by the reduced energy of the single pulses nearer to the optimum value.
Recent investigations on the application of pulse bursts on copper samples suggest an interaction of the single pulses in a pulse burst in terms of the specific removal rate. The specific removal rate drops to less than 50% for a 2-pulse-burst consisting of two pulses of identical pulse energy, whereas the maximum specific removal rate for a 3-pulse-burst exceeds that of a single pulse by approx. 20%.
The results of investigations on the variation of pulse energy for 2-pulse-bursts and 3-pulse-bursts regarding specific removal rate and surface quality are presented.