No abstract

No abstract

The effect of varying fluence for laser microprocessing of Al and Cu is studied at a pulse duration of 120 fs at atmospheric pressure. For low fluences (<2 J/cm 2) quality is relatively good for both metals but completely melt free processing does not seem to be possible. For fluences above 2 J/cm 2, a huge difference is observed between Al and Cu. Important roughness and clear evidence for remelted and recast matter solidified like spikes, as well as significant burrs at the edge are observed for Al. In the case of Cu the micromachining quality is high, with practically no redeposit matter and low roughness in the bottom of the groove. An analysis is given in terms of processes of a thermal nature underlining the role of electron-phonon coupling. The existence of an "optimal point" for micromachining is also evidenced

No abstract

Experimental results related to the influence of time delayed pulses for ablation efficiency with short multi pulses (pulse duration of 5 ps) are reported. A significant improvement of the micro structuring quality at relatively high fluence regime in metals is obtained. Less removed or recast matter is observed and the processed surface appears to be smoother with better roughness. Ablation depths and burr heights are compared for single pulses and double pulses in steel, Al and Cu as a function of scans number. Best results are obtained for weak time delays, typically less than 1 ps