New perspectives for 3D US scanners in air

A new interest for scanners of solid objects is growing in manufacturing industry. This work is addressed to investigate potential applications of ultrasound for designing new airborne ultrasonic scanners. A prototype of ultrasonic scanner is built to reconstruct three-dimensional profiles of objects. The developed system is based on a scanning probe with five airborne transducers. The transducers are made with hemicylindrical shape with thin PVDF film and resonant frequency 61 kHz. The distance measurements are carried out with unimodal transducers and they are obtained by a digital phase measurement technique that allows sub-millimeter resolution in controlled environment. The probe simulates a cylindrical array that can host objects of maximum width 20 cm and height 40 cm. An algorithm is proposed to use efficiently the distance information for the calculation of the object contours also with coarse sampling of the cylindrical array aperture. We will show results obtained with laboratory measurements on a wooden cone and compared with simulated results.