Ultra-Broadband Ultrasonic Imaging Using Bi-Layer Structure Probe

Abstract

An ultrasonic imaging system to employ ultrasounds whose bandwidth is over two times compared to the conventional ultrasonic diagnosis equipment is invented. Assuming a receiving transducer and a transmitting transducer separately, the present system is improved to get high signal to noise ratios even at high frequencies by using a broadband transducer made from polymer piezoelectric materials particularly for the reception. Two transducers are unified in a bi-layer structure so as to be used for the conventional equipment. A bi-layered probe consisting of a ceramic transmitter and PVDF receiver is prototyped. A capability of detecting the second to tenth harmonic sounds contained in the echo signal, which are generated during the propagation, is experimentally demonstrated. The images for a phantom are then generated using each harmonic component. Finally, it is shown that the superposition of higher harmonic images reduces the speckle noise