Parameters of influence in surface ablation of metals with using a high power tunable ultrafast laser

Abstract

High power ultrafast lasers are nowadays able to provide high ablation rates and meet the technical requirements and performances needed for many industrial applications. However depositing more energy into the target material may induce heat accumulation. Consequently it enhances the ablation efficiency as well as introduces some detrimental effects on the processing quality. Thus, to identify parameters of influence (pulse duration, repetition rate, fluence, pulse overlap, scanning velocity…) and their operating windows enabling to maintain the highest processing quality is a key issue.In this paper, we present some comparative results on surface ablation of Aluminum, Copper and Molybdenum in both picosecond and femtosecond regimes. All trials have been performed using a single tunable Yb-doped fiber ultrafast laser with a pulse duration ranging from 350 fs to 10 ps, a repetition rate ranging from 250 kHz to 2MHz, and an average power up to 40 W. Ablation efficiency and process quality are evaluated by means of 3D optical profile measurements and SEM respectively. We will show that the effect of pulse duration on ablation efficiency is highly material dependent meanwhile the repetition rate has no major influence on ablation efficiency in the investigated range.