Enhanced polymer ablation rates using high-repetition-rate ultraviolet lasers

Etch rates (/spl mu/m/pulse) for glycol-modified polyethylene terephthalate (PETG) under pulsed UV (255 nm) laser processing are measured as a function of pulse repetition frequency in the range 0.7-15 kHz. Materials removal rates (/spl mu/m/s) scale approximately linearly with pulse repetition frequency at a fluence of 0.59 J/cm/sup 2/, and there appears to be no attenuation of the ablating laser beam by the ejected material plume for pulse rates up to 15 kHz. The instantaneous etch rate for pulses in a sequence increases markedly (/spl sim/40%) for long pulse sequences (>100 pulses) at high PRF (15 kHz), an effect which can be used to increase machining rates while operating at a moderate laser fluence.