About the effective thermal and optical parameters of a two-layer structure in photothermal phenomena

Abstract

The model for the ca1culation of effeetive thermal parameters in two-layer structure in photoacoustic phenomena proposed in previous works (1-4) is used for defining and ca1culating the effective optical parameters. The concept of effective optical absorption coefficient will naturally emerge from the model when a heat source, depending on the position and the optical absorption coefficient, is taken into account. Results for the static limit shows that, in general case, the effective optical absorption coefficient value depends on the effeetive thermal conductivity, and it is different for rear-surface and front-surface illumination configurations. For optically opaque samples in rear-illumination configuration and optically transparent layers, it is show that the effective optical absorption coefficient and the effective thermal conductivity are independent and can be separately obtained. The latter result suggests for optically transparent samples, it will be correet to use the Maxwell Equations for defining and ca1culating the effeclive oplical parameters in multilayer structures.