Phase lock-in thermography for thermal diffusivity measurement and layer surface characterization

Abstract

A new method relying on modulated photothermal radiometry with laser heating is presented for characterization of the thickness and the thermal diffusivity of materials. This non-destructive and contactless method is based on phase shift measurement between modulated laser power and thermal signal at different modulation frequencies. New simple formulas were found for thickness and thermal diffusivity determination for metal samples. The experimental setup is presented. Layer on substrate is studied with theoretical 3D-model developed in our laboratory. First measurements on virgin and oxidized nuclear fuel cladding are presented.