Ultrasonic sensor for reconstruction of marble quarries prospecting

To perform an ultrasonic marble quarries reconstruction it is necessary to use an echographic method. At the employed frequencies, the commercially available transducers have an active emission surface diameter which is too small in comparison to the ultrasonic wavelength. As a consequence, a very wide radiation lobe propagation occurs leading to energy spreading and to surface propagation which masks the signal coming from the inner portion of the quarry. These effects make the echographic method inapplicable. The goal of our research is to realize a new sensor capable of increasing the ultrasonic beam directivity. A parabolic shaped holder was designed with the piezoelectric element positioned in the focus. By exploiting the parabolic reflector properties, the spherical wave is collimated in a quasi-plane wave on the parabolic focal surface