Intra-Burst Interaction During Ultrashort Pulsed Laser Structuring of Metals with Variable Temporal Pulse Spacing

One approach to increase productivity of ultrashort pulse laser processing is the use of pulse bursts. The small temporal spacing between the pulses within a burst results in an increasing influence of intra-burst heat accumulation, shielding effects and redeposition of ablated material. Even an increase in ablation efficiency can be achieved by bursts. To gain a deeper understanding of these effects, burst ablation with flexible intra-burst pulse spacing is investigated. The industrial relevant materials cop per, aluminum and stainless steel are compared regarding their dominating effects based on the pulse ablation efficiency. Surface effects and the ablation quality achieved are evaluated by means of the surface roughness. The time periods of the secondary effects redeposition, shielding and amplified ablation are identified and discussed for all three materials. Thus, a great potential for highly efficient tailored burst processes by adjusting the temporal pulse spacings is shown.