Inversion of pulsed thermal-wave images for defect sizing and shape recovery

摘要

Abstract: An outstanding problem of thermal wave imaging has been blurring of the images caused by lateral diffusion of heat in the sample. In this paper we describe a technique for removing this blurring in images of planar subsurface features such as delaminations. This technique is based on a model which allows us to develop an algorithm which performs a mathematical inversion of the scattering process when it is applied to experimental data. The result is a theoretical and experimental demonstration that the blurring of thermal wave images is not due to any inherent loss of information in the diffusion process, but that it can, in fact, be removed by appropriate processing of the image. The result is a very significant improvement of the resolution of the imaging process.!0