Studying the bulk dynamic strength of a quartz glass by laser-induced breakdown

Methods and results of the investigation of pulsed pressures excited in the bulk of a quartz glass by focused nanosecond laser pulses (lambda = 1.06 mum, tau(0.5) approximate to 12.5 ns) are described. The experiments were performed in a wide range of laser power densities, which allowed the generation of pulsed pressures to be studied for both thermomechanical effect and optical damage in the bulk of glass. We have measured displacement of the free sample surface (laser interferometry), determined optical damage thresholds, and performed fractographic analysis of the fracture zones. The results revealed nonlinear thermomechanical response and allowed us to estimate the change in the optical absorption and temperature of the material near the optical damage threshold. Quantitative data are obtained on the relative efficiency of pulsed pressure production during the thermomechanical effect and optical damage. Data on the dynamic strength of a quartz glass are obtained for the first time in the absence of a damaged surface layer. Using the proposed method, it is possible to determine the energy consumption for the fracture of brittle materials. High sensitivity of the method of laser-induced breakdown allows this technique to be used for studying the influence of microstructure on the mechanical and optical properties of transparent media. (C) 2004 MAIK "Nauka / Interperiodica".