Characterization of interfaces by photothermal methods

An overview is given of the ability of photothermal techniques to detect hidden interfaces in solid-state samples. The photothermal signal behaviour for horizontal, vertical and randomly distributed interfaces is described. Methods for imaging buried thermal inhomogeneities are discussed. Selected applications are given which demonstrate the potential of the photothermal approach to measuring layer thickness and coating adhesion, to tracing cracks and pores and to evaluating microstructured or crystalline specimens.