Measurement of Ultrasound Velocity and Attenuation in Liquid Using Multi-modes Leaky Lamb Wave Device on LiNbO₃ Substrate

Abstract

A reflection-type interference method for measuring the sound velocity and attenuation in a liquid using a multi-modes leaky Lamb wave device is described. The present method has the advantage of the measurement in a small quantity of liquid at plural frequencies by the use of one transducer. From the numerical analysis of the propagation characteristics of leaky Lamb waves on a 128° rotated Y cut-X propagation LiNbO₃ plate, a small-size leaky Lamb wave device with multifrequencies operation is realized. The fast Fourier transform (FFT) of an interference signal between an input signal and a received one makes it possible to shorter the acoustic path length in the liquid. As a result, the measurement error of the present technique is within 0.2% for the variable sound path length of 5 wavelengths.