SOME RECENT APPLICATIONS OF LASER ULTRASOUND TO THE CHARACTERISATION OF MATERIALS

Laser techniques for ultrasonic generation and reception have potential for a wide range of non-contact measurements, chiefly because they can be used for defect detection and materials characterisation at elevated temperatures. However, these techniques have other advantages. Unlike contact transducers, they do not disturb elastic wave propagation by loading the surface of the specimen. They are also capable of much higher temporal and spatial resolution than can be obtained by most conventional techniques. This paper will present some recent applications of this technology to a range of materials. The first two exploit the non-contact characteristics of laser ultrasound for surface characterisation following, respectively, plasma-sprayed coating and laser hardening. The remaining applications exploit the high temporal and spatial resolution for the acoustic characterisation of various composite materials, i.e. glass-fibre and carbon-fibre reinforced plastics and a metal matrix composite