Espectroscopia de espelho térmico com excitação pulsada : caracterização de materiais opacos

Abstract

The time-resolved Thermal Mirror technique is developed under pulsed laser excitation for measuring thermal and mechanical properties of opaque materials. Heat diffusion and thermoelastic equations are solved analytically for pulsed excitation assuming surface absorption and an instantaneous pulse. Analytical results for the temperature change in the sample is compared to all-numerical solutions using finite element method analysis accounting for the laser pulse width . Experiments are performed which validate the theoretical model and regression fitting is performed to obtain the thermal diffusivity and the linear thermal expansion coefficient of the samples. The values obtained for these properties are in agreement with literature data. The technique is shown to be useful for quantitative determinations of the physics properties of metals with high thermal diffusivity.