Measurement of surface acoustic wave attenuation in aluminum using transverse acoustic field

This paper deals with the estimation of the attenuation of surface acoustic waves (SAWs). The proposed solution consists in measuring the displacement field transversely to the axis of propagation of the acoustic beam at several distances from the transducer, considering the entire field. Unlike measurements taken along the beam axis (the usual configuration), these transverse measurements avoid any positional error with respect to this axis. Furthermore, measurements in perpendicular planes integrate the beam’s total energy, allowing divergence to be taken into account. Finally, as the measurement is carried out in the very near field (corresponding to the first tenth of the Fresnel zone), the SAW beam still has sufficient amplitude, enabling measurements to be made in a wider frequency range up to several tens of megahertz. The results of attenuation measurements on an aluminum sample at frequencies ranging from 10 to 50 MHz using the two approaches mentioned are reported, demonstrating the benefits of the proposed method in terms of measurement error.