Numerical System For Infrared Scanners And Application To The Subsurface Control Of Materials By Photothermal Radiometry

Non-destructive testing (NDT) of materials can be achieved via proper photonic excitation and radiometric monitoring of the induced thermal changes. The theoretical support for this photothermal conversion in bi-layered materials is proposed, single-pulse and periodically modulated fluxes being considered. Some practical proposals are derived concerning the various aims of NDT: coatings thickness measurements, detection of defective bondings or delaminations, measurements of contact resistances between two layers. Measurements performed with a commercially available infra-red scanner and a digital data acquisition and processing system are reported.