Detection of harmonic signals by separately arranged transmitting/receiving ultrasonic transducer

摘要

An ultrasonic transducer with a circular aperture, in which a piezoelectric element for transmitting finite-amplitude pulses and a piezoelectric element for receiving their harmonics generated in a nonlinear medium are arranged coaxially were designed and fabricated. The diameter of the transducer is 6mm and its center frequency is 5MHz. Using this transducer, we carried out measurements of the sound field characteristics, and then developed ultrasonic imaging for a sponge phantom. Compared with a conventional transducer, higher sensitivity higher selectivity and better imaging can be obtained by determining successfully the combination of piezoelectric constants, Q values and sound velocities between the transmitting and receiving elements.