Laser infrared photothermal radiometric depth profilometry of steels and its potential in rail track evaluation

Laser Infrared Photothermal Radiometry has been utilized for several thermal-wave inverse-problem NDE applications. These include depth profilometry of steels and rails and scanning tomography of sub-surface defects in steels. Further, a computational algorithm has been refined to address the ill-posedness of the thermal-wave inverse problem. As a result, depth profiles of case-hardened steels, railway track heads from the field, and machined sub-surface hole thermal-diffusivity images have been reconstructed successfully using this emerging NDT technology.