Characterization of the Sound Field Generated by an Ultrasonic Transducer in a Solid Medium by Rayleigh-Sommerfeld Back-Propagation of Bulk Acoustic Waves Measured with Double-Pulsed TV Holography

The established approach for the characterization of sound beams is the acquisition of experimental data by measuring the acoustic field pressure distribution in a fluid medium, which is usually done with point detectors (hydrophones, microphones) or arrays of detectors. From these point measurements, important characteristics of the sound field emitted by the transducer (such as the axial and transversal beam profiles, focal length or beam spread) can be derived. When the propagation medium is a solid, these characteristics are normally obtained from the measurement of pulse-echo signals that arise from the interaction of the sound beam with targets placed in the material, such as metal balls embedded in plastics, or flat-bottom or side holes drilled in metallic blocks [1]. These measurements are more difficult to perform and provide a sparser set of data compared to the immersion techniques.