ABSTRACT
The problem of laser generation of ultrasound is out of the scope of this paper, but we can nevertheless note that the only mode that is truly non destructive is the thermoelastic mode.
Two types of displacements are generated at the surface when the ultrasonic wave is reflected: normal displacement and in plane displacement. The detection systems we will describe are mainly developed to measure normal displacement but they can, in some cases, be adapted to the measurement of in plane displacement.
