Ultrasonic imaging using laser generation and piezoelectric air-coupled detection

A non-contact ultrasonic system using a pulsed laser source and a wideband 1-3 connectivity PZT/epoxy composite transducer as a receiver has been used to produce images of defects in a variety of materials. Using both time and frequency information, through transmission images have been formed of delaminations and machined defects in both carbon fibre reinforced polymer (CFRP) and pultruded glass-fibre reinforced composites. Lamb waves have also been used to reconstruct tomographic images using a filtered back projection algorithm, for defects in thin plates of CFRP and Perspex.