Ultrasonic interferometric characterization of material plates

Much of the work on the ultrasonic nondestructive characterization of materials involves either their ultrasonic velocity or their attenuation. Presented here is a technique that allows simultaneous measurements of velocity and attenuation for longitudinal as well as shear modes of propagation in a medium. This technique is based on the propagation of ultrasonic continuous waves through a plate and on a correlation analysis between incident and transmitted signals. The method is an extension of a previously proposed technique, which was applicable only to specimens designed in the shape of a wedge. The effect of varying the acoustic path through the material is obtained by slowly rotating the specimen with respect to the direction of the incident beam