Considerable progress has been made in recent years in the development of signal processing algorithms for use in ultrasonic non-destructive evaluation which yield the size, shape, and orientation of a flaw. This kind of flaw information is necessary in order that failure predictions of materials and components can be made from non-destructive tests. The signal processing algorithms that have been developed for ultrasonics are based upon both direct and inverse approximate solutions to the elastic wave scattering problem, and cover various ranges of the parameter ka where k=2π/λ is the wave number of the ultrasound and a is a flaw size dimension. In order to use these algorithms effectively in the determination of flaw parameters, it has been found necessary to obtain measurements of the flaw at several viewing angles. At this time, there is no ultrasonic transducer available which permits this to be done efficiently and conveniently in the long and intermediate wavelength end of the spectrum. This region has been shown to be quite rich in flaw information and is appropriate to ultrasonic NDE in many practical applications (e.g., thick wall sections).