Tissue ablation through water with erbium:YAG lasers.

We report the dynamics of vapor cavities generated by 200 microseconds long Er:YAG laser pulses under water and in gelatin. Acoustic transients were detected at the beginning of the laser pulse and when the cavity collapsed. Cavity expansion and collapse, and the associated acoustic transients are possible ablation mechanisms with the Er:YAG laser. Shortening of the pulse duration is suggested to minimize long range under water tissue damages.