Ultrasonic technique for sizing voids by using area functions

A technique is reported for determining the sizes of voids in structural materials by the inversion of backscattered ultrasonic signals using the area function formula. The formulation of this method is based on the Born approximation which is a weak scattering approximation, but it is shown to work well for voids. Results for extracting the radii of spherical voids, or the tangent plane distances, of spheroidal voids are presented, using theoretical and experimental scattering data.