Highly versatile thickness measurement of almost all coatings

How laser photothermal technology works

A laser source illuminates the surface of the coated object. Part of this laser light is absorbed by the coating material and transformed into a non-destructive heat wave that starts to diffuse into the coating material depth-wise. When it arrives at the interface with the substrate, the contrast between the thermal properties of the two materials and the interface gap between them generate a backward diffusion of the heat wave. On return to the coating surface, this heat wave emits a thermal infrared flux into the air. An optical system then collects this thermal flux and focuses it on an infrared sensor. By comparing this thermal signal with the laser signal transmitted to start with, it is possible to determine the delay between the two signals, which is directly proportionate to the coating thickness.