A new point-source/point-receiver acoustic transducer for surface wave measurement

Abstract

Abstract This paper presents the development of a new acoustic transducer for measuring surface wave velocity using miniature conical PZT elements. The elements are directly fabricated out of a polarized PZT ceramic plate by excimer laser micro-machining technique. The aperture size of the machined PZT conical elements is around 200–400 μm in diameter, which allows high-frequency generation and detection of surface waves. Two of the transducers are assembled together to form a transmitter/receiver pair. Driven by a tone-burst electrical system, the transmitter acts as an acoustic point-source which launches surface acoustic waves propagating along a sample surface. The receiver then detects the surface motion. The transfer function of the transmitter/receiver system is experimentally determined. With a waveform comparison method, the surface wave velocities are obtained from the measured signal waveforms. Experimental results on several samples show that the surface wave velocity can be determined accurately. Finally, the transducer is applied on anisotropic solids. The variation of surface wave velocity as a function of propagation direction is determined.