Product Code: ICAL08_M403

Efficiency Aspects in Processing of Metals with High-repetition-rate Ultra-short-pulse Lasers
Authors:
Gediminas Raciukaitis, Institute of Physics; Vilnius Lithuania
Marijus Brikas, Institute of Physics; Vilnius Lithuania
Mindaugas Gedvilas, Institute of Physics; Vilnius Lithuania
Presented at ICALEO 2008

Production time and quality are main concerns in competition of laser technologies in microfabrication with other diverse methods. Ultra-short pulse lasers can offer extraordinary precision in nanometer scale when laser fluence is close to the ablation threshold. High pulse energies or high repetition rate are usually proposed to be used for an increase in productivity of the system. We discuss experimental and modeling results on effects of both laser parameters to ablation threshold, energy coupling and heating of the workpiece in case of metals. High repetition rate is favorable for the ablation threshold. The threshold decreases with irradiation due to defect formation and modification of the surface causing better energy coupling into material. On the other hand, considerable portion of energy from the laser pulse is converted to a heat even when ultra-short pulses are applied. The heat is dissipated in surrounded material causing rise in temperature of the workpiece. Plasma which is formed in picosecond time domain well absorbs laser energy in all spectral range and affects an energy coupling to the workpiece. Balancing between the rate of energy introduction and accompanying alterations in material and surrounding requires new strategies for effective use of the laser energy.