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Surface acoustic wave generation and detection by Coulomb excitation

Excitation and detection of acoustic waves in piezoelectric materials relies on a gradient in the piezoelectric properties respectively a gradient in the electric field. The relatively weak coupling is usually enhanced for established practical applications by mechanical, geometrical and electrical resonances. The geometrical resonances, as present for the commonly used inter digital transducer (IDT), lead to limitations concerning the spatial and temporal resolution that can be achieved with such devices. Concentration of the electric field by geometrical means and point like conversion at the surface of piezoelectric materials is the basis for the novel scheme presented here. The principles of the developed method together with instrumental details are discussed. Applications involving two dimensional imaging with time resolved recording for each pixel of the image for phase and magnitude of the transfer and echo signals are presented.