Airborne Ultrasonic Probes: Design, Fabrication, Application.

Based upon a piezoelectric 1-3 composite material, air-borne ultrasonic probes for frequencies up to 2 MHz were developped. These probes are characterized by a bandwidth larger than 50% as well as a signal-to-noise ratio higher than 100 dB. Applications are the thickness measurement of thin powder layers, the inspection of sandwich structures, the detection of surface near cracks in metals or ceramics by generation/reception of Rayleigh waves and the inspection of plates by Lamb waves.