Measuring the In-plane thermal conductivity of a metallic thin foil by Pulsed Infrared Thermography

The analytical solutions of the heat conduction differential equation in 2D case, due to an instantaneous point source of heat is particularly simple; the basic equation permits to measure the thermal diffusivity of thin metallic foils by measuring the in-plane spreading, as a function of time, of the gaussian function.The analysis can be carried out as well in the spatial frequency domain. A laser shots one side of the metallic foil and a thermographic camera collects a sequence of temperature images on the back side, that are furtherly analysed according to the corresponding equation in the spatial frequency domain. Density and specific heat are measured, and the thermal conductivity is finally evaluated. The ratio between thermal and electrical conductivities is considered in the frame of the Wiedemann-Franz law.