Femtosecond laser ablation of brass: A study of surface morphology and ablation rate

The interaction of near infrared femtosecond laser pulses with a Cu based alloy (brass) in ambient air at atmospheric pressure and under different laser conditions was investigated. The effects of laser fluence and number of pulses on surface morphology and ablation rate were studied using scanning electron microscopy (SEM) and optical microscopy. Ablation rates were found to rapidly increase from 83 to 604 nm/pulse in the fluence range 1.14-12.21 J/cm(2). At fluence > 12.21 J/cm(2), ablation rates increased slowly to a maximum (607 nm/pulse at 19.14 J/cm(2)), and then decreased at fluence higher than 20.47 J/cm(2) to 564 nm/pulse at 24.89 J/cm(2). Large amounts of ablated material in a form of agglomerated fine particles were observed around the ablation craters as the number of laser pulses and fluence increased. The study of surface morphology shows reduced thermal effects with femtosecond laser ablation in comparison to nanosecond laser ablation at low fluence.