ANALYSIS OF SURFACE-LAYER VARIATIONS BY PHOTOTHERMAL MEANS

The geometrical and physical properties of the surface and the near-su rface layers can be modified by a mechanical or a thermal impact. If t hese variations are coupled with a modification of the thermal propert ies, they become detectable by photothermal means. In order to perform some fundamental experiments, we chose the Vickers hardness test as a model for a slight and reproducible mechanical impact. The surroundin gs near the deformed areas were scanned; the optical beam deflection a s well as the radiometric signal were measured and compared with the o ptical microscopic images.