Dynamics of surface processes in a transparent dielectric exposed to laser radiation

High-speed interference filming is used to study the dynamics of development of the change region of a surface vapour–plasma formation under the action of laser radiation with a power density up to 10⁷ W cm^-2 and a pulse duration of ~1 ms on polymethyl methacrylate samples of thickness up to 1 cm. Experiments show that damage region is mainly produced due to a thermal mechanism along with the possible effect of the emerging elastic vibrations. It is also shown that the damage takes place predominantly at the initial stages of the process (up to 100 μs) due to shielding of the sample by a vapour–plasma cloud and scattering of radiation from the liquid-drop phase.