Precise measurements of Thermal Diffusivity by Photothermal Radiometry for Semi-infinite Targets using Accurately Determined Boundary Conditions.

Abstract

An experimental set-up was developed at the NPL with the goal of improving the accuracy of photothermal measurements. The principle is to perform accurate measurements of the experimental boundary conditions during a photothermal radiometry experiment. A numerical 3D heat diffusion model based on thermal transfer functions has been developed to use the measured boundary conditions. To prove the validity of this methodology, the thermal diffusivities of pure metal samples were estimated from experimental thermal radiance data by a least-squares fitting to the model. Experiments carried out at about 900K demonstrate good agreement between the theoretical and experimental data and accuracies of about 1.5% for thermal diffusivity measurements. (Received on June 21, 2000; Accepted on October 22, 2000)