Rayleigh wave excitation with an elliptical reflector for high-power ultrasound

Abstract

This study proposes a Rayleigh wave transducer with an elliptical reflector for high-power ultrasound (ELIPS). In contrast to conventional transducers using IDT with single crystal piezoelectric plates or wedge transducers, our ELIPS enables high-power Rayleigh wave excitation in the megahertz range, which will be useful for applications such as surface acoustic wave (SAW) motors, SAW tactile devices, and SAW atomizers. The driving principles of the transducer are Rayleigh wave excitation with a transverse wave source and transverse wave focusing with a dilatational wave source and an elliptical reflection surface. The effectiveness of this mechanism was confirmed with an FEM simulation, and the Rayleigh wave excitation was validated using a prototype transducer. Finally, the high-power characteristics were examined, and a maximum vibration amplitude of 15.5 nm at 1.0 MHz was successfully obtained. It should be noted that this vibration amplitude is not a saturated value, and a much higher value could be realized with higher input power.