Parametric transducer for high-speed real-time acoustic imaging

The letter reports the development of a novel high-speed scanning acoustic imaging system, potentially suitable for medical diagnosis, nondestructive testing and acoustic microscopy. The key element of this system is a parametric transducer, consisting of a photoconductor-piezoelectric sandwich in which the nonlinear behaviour is the basis of an optical-readout method. Preliminary measurements at 2.7 MHz have indicated that the sensitivity is better than 0.2 ¿W/cm2, and a resolution approaching the expected limiting value of 0.7 mm has been achieved.