A New Ultrasonic Transducer to Decrease the Multi-Reflections Which Cause Artifacts on B-Mode Imaging

Abstract

We propose a design that decreases the acoustic energy reflected by an ultrasonic t ransducer f or medical use. Multi-reflections must be reduced to achieve good images without artifacts. This can be done by decreasing the transducer's r eflection coefficient. The reflection coefficient is important, and must be taken into a ccount t ogether with efficiency and bandwidth when considering design. Input acoustic impedance is assumed to be that seen from the transducer's surface to the backing material through the matching layers a nd piezoelectric ceramic (PZT). Input acoustic impedance at the center frequency is designed to equal t he acoustic impedance of the load. We analized the reflection c oefficients of several transducers by computer simulation. We found a structure that provides a small reflection coefficient, good efficiency, and a wide bandwidth. The reflection coefficient of the thin-disk transducer we fabricated is 10 dB lower than that of a conventional transducer.