Characterization of continuously inhomogeneous media with arbitrary thermophysical profiles using photothermal technique

A numerical method of determining depth profile of thermo-physical parameters of an inhomogeneous sample is presented. By dividing the inhomogeneous material into number of sublayers in which each single layer can be treated as homogeneous, the thermal-wave field of the material is obtained based on recurrence relations of thermophysical parameters of each divided layer. A numerical algorithm of determining the depth profile of thermophysical parameters in the continuously inhomogeneous material under excitation of arbitrary beam size has been demonstrated by a polynomial fitting process for three arbitrary generated thermophysical profiles.