ACOUSTIC DETERMINATION OF ABLATION THRESHOLD FLUENCES OF MATERIALS PROCESSED WITH FEMTOSECOND LASERS

D. J. O. ORZI; F. C. ALVIRA; G. M. BILMES

Playa del Caren

Conferencia; XI International Conference On Laser Ablation; 2011

Laser micromachining processes and generation of nanoparticles by pulsed femtosecond laser ablation are techniques that require a carefully determination of the energy deposited over the samples. In many cases, best results are obtained by using work fluences slightly above the Ablation Threshold Fluence (ATF). Therefore, accurate determination of the ATF is an important requirement in these techniques. ATF can be obtained by measuring the intensity of the acoustic signal generated during the ablation process as a function of the incident laser fluence[1]. In this work laser ablation threshold fluences of different types of substrates and surface films treatments were determined by using acoustic detection. Ablation was made during material processing by using a pulsed Ti:Sapphire (120 fs, 1 mJ, 1 kHz and 800 nm) infrared laser of a  micromachining station by using fluences (F) between 0<F<10 J/cm2. A cheap electret microphone was used for detection. We determined by this method ablation thresholds fluences of steel, silicon, glass, plastics and SiON. The results were compared with similar data obtained by ablation with a pulsed Nd:YAG nanosecond laser.