Thermal energy coupling to Al in ablation with ms-, ns-, and fs-laser pulses

Residual energy coefficient defined as the ratio of thermal energy retained in aluminum sample following laser ablation to the energy of incident laser radiation as a function of laser fluence was studied. Experiments were performed in various gas media with the use of ms-and ns-ruby, ns-Nd:glass, and fs-Ti:sapphire lasers. For ns- and fs-laser pulses an abrupt significant rise of residual energy coefficient of aluminum occurs above the ablation threshold in a gas medium and does not occur in vacuum. For ms-laser pulses the residual energy coefficient increases slightly both in air and vacuum in the range of laser fluences above the ablation threshold.