NON DESTRUCTIVE EVALUATION AND THERMAL CHARACTERIZATION BY THE PHOTOTHERMAL BEAM DEFLECTION

The photothermal methods are known to be a useful tool for thermal characterization of materials. Among all these methods only those for which accurate theoretical models are available allow quantitative measurements. In addition it is often necessary to test locally large samples without any contact. All these conditions are fulfilled by the photothermal beam deflection (mirage effect). Let us recall that this optical method uses a first modulated light beam (pump beam) to heat the sample and a second beam (generally from a small He-Ne laser) which is deflected by the thermal gradient in the vicinity of the sample surface (probe beam)