ULTRASONIC-IMAGING USING LASER GENERATION AND PIEZOELECTRIC AIR-COUPLED DETECTION

A non-contact ultrasonic system using a pulsed laser source and a wide band 1-3 connectivity PZT/epoxy composite transducer as a receiver has been used to produce images of defects in a variety of materials. Usi ng both time and frequency information, through transmission images ha ve been formed of delaminations and machined defects in both carbon fi bre reinforced polymer (CFRP) and pultruded glass-fibre reinforced com posites. Lamb waves have also been used to reconstruct tomographic ima ges using a filtered back projection algorithm, for defects in thin pl ates of CFRP and Perspex.