Size effects and determination of absolute temperature increases in laser heating of dielectrics

Cw laser heating of dielectrics of small sizes is investigated both theoretically and experimentally. Integrating the heat equation numerically allows to calculate the temporal and spatial evolution of the laser-induced heat wave along the crystal surface. Temperature measurements with a thermocouple agree qualitatively with the calculations, but no reliable absolute values of surface temperature can be obtained this way. As an alternative a thin film ‘thermometer’ - the photodesorption process from a layer of Na clusters - is used which provides temperatures valeus that agree quantitatively with the calculations.