Hydrodynamic effects on the molten surface of a laser-irradiated aluminum sample

The role of excimer laser pulse energy density was investigated in connection to the turbulence of the molten bath induced by laser irradiation. Gentle hydrodynamic effects are observed on the surface of a laser-irradiated aluminum surface, when the laser energy density substantially exceeds the melting threshold. Chaotic fluid motion inside the molten bath is observed above a laser energy threshold value which, in the present case of KrF excimer laser irradiating aluminum, is between 7.5 and 8.5 J/cm2. Liquid wave motion, which results in typical wavelike frozen structure, can be induced in a reproducible way thus permitting a controlled tailoring of the surface morphology.