High Frequency Acoustic Sensor Dedicated to the High Resolution Measurement of Mechanical Properties

Abstract

Through acoustic signature, scanning acoustic microscopy can be used to quantify local mechanical properties of a medium thanks to the generation of surface waves, mostly Rayleigh waves. Despite being quite effective, this method requires to evaluate the mechanical properties of a single point the acquisition of many ultrasonic signals. This process is then time-consuming and is hardly adaptable to quantitative imaging. The solution considered in this paper to speed-up the method is to design a multi-element sensor allowing the extraction of information on Rayleigh waves with a reduced number of acquisitions. The work is conducted along two axes. As a first step, a model allowing the simulation of the acoustic wave behavior at a fluid/solid interface is developed. This model leads to a better understanding of the characterization of the mechanical properties and to the definition of an adapted sensor's design. As a second step, an experimental method for acoustic field reconstruction is used to characterize the multi-elements sensor and measurements of mechanical properties were done.