Defect detection by surface acoustic waves generated by a multiple beam laser

Laser-induced Surface Acoustic Wave (SAW) pulses of large amplitude have been launched on the surface of metallic samples. The non contact generation process involves a rectilinear set of photothermal sources equivalent to a phased array of ultrasonic transducers. Line and point source arrays created by a 16-beam YAG laser have been implemented. Two sets of experiments are presented: i) non destructive testing of thin surface breaking slots with giant SAW pulses launched by the line source array, ii) sectorial beam scanning of the surface by SAW generated by the point source array.