Résolution spatiale de la caméra thermique à source volante

Abstract The photothermal camera (flying spot camera) is an instrument fer non destructive testing, where a heat source and an infrared (IR) detector together scan the material surface. The detector monitors the temperature rise induced by the moving heating spot. This technique has been used for many years for thin coatings characterisation and for crack detection. We did not find any quantitative analysis about its spatial resolution in the literature. Our objective was thus to perform a theoretical analysis on the flying spot camera resolution. It actually depends on the photothermal ‘accident’ that is met during the scanning. Due to their importance and/or occurrence in NDT, the following photothermal ‘perturbations’ were analysed: emissivity variation, absorptivity variation, joint emissivity and absorptivity variations, and finally a thermal resistance perpendicular to the surface (model for open cracks). For all cases, we discussed the influence of various experimental parameters: heating spot size, IR measurement spot size, scanning velocity…