Thickness Determination for Two-Layer Systems of Paint on Polymers with Photothermal Radiometry

Thickness determination of paint is of interest for industrial applications. While there are conventional methods if the substrate is a metal, only thermal waves can be used if the substrate is a polymer. The purpose of this paper is to extend the work performed on one-layer systems to make it applicable to a two-layer system. Results are shown for systems where either both layers are opaque or where the upper layer is transparent. A method is discussed to determine both thicknesses.