System for Measuring Sound Velocity in Liquid Using Leaky Lamb Wave Modes on 128°Rot. Y-X Cut LiNbO₃ Substrate

Abstract

A system for measuring sound velocity in liquid is constructed using an interdigital transducer for leaky Lamb waves on a 128° rot. Y-X cut LiNbO 3 substrate. The leaky Lamb wave device is composed of a 1-mm-periodicity interdigital transducer and a counter electrode on each surface of the 0.5-mm-thick piezoelectric substrate. The device is operable for 8 modes in the frequency range of 2∼25 MHz at a water-solid interface. The measurement principle of this system uses the interference between a rf pulse signal and a reflected signal. The system successfully measures the absolute sound velocity in some liquid samples. The measurement resolution of the system is within 0.1%.