Multiparameter Thermal Tomography

Abstract

Thermal imaging is a rapidly emerging area as it offers the capability for full field quantitative nondestructive evaluation. In particular, thermal techniques can be used to accurately measure material parameters (thermal conductivity, heat capacity) on a local basis. Here we describe a tomographic reconstruction technique that can be used to image both thermal conductivity and heat capacity from heat conduction data. This requires the ability to accurately measure surface temperature evolution at any point on the surface of a body due to a localized thermal excitation such as a laser source. Two independent parameters: maximum temperature and time for reaches this maximum (transit time) are required for the reconstruction. Using a coupled parameter version of the Algebraic Reconstruction Technique (ART) one can reconstruct the two thermal parameters tomographically. Results from simulated data are presented to illustrate the utility of the approach.