Excitation of Rayleigh wave with sapphire/LiNbO3 mechanical integration for surface acoustic wave motor

Abstract

The surface acoustic wave (SAW) motor, as a type of traveling wave ultrasonic motor, has been studied for years. A Rayleigh wave is excited by a unidirectional interdigital transducer (U-IDT) in a lithium niobate stator. Through frictional force, a driven slider can achieve linear motion. At the contact surfaces of the stator and slider, one problem observed is the lack of tolerance to wear. Owing to the large mohs hardness, a novel approach to the fabrication of a sapphire stator is investigated to improve frictional durability. In the novel sapphire stator, the Rayleigh wave, generated by the lithium niobate U-IDT transducer, is transmitted to the sapphire stator surface through pure mechanical integration. Through measurement results, the sapphire stator is evaluated via the admittance characteristics of the wave excitation unit, the normal vibration of the Rayleigh wave, and the horizontal vibration velocity of the Rayleigh wave.