Surface acoustic wave bridge for rotation measurement

摘要

A surface acoustic wave bridge for rotation measurement which uses acoustic waves propagated in opposite directions about the circumference of a rotor. The acoustic waves are generated by a transducer adjacent the rotor which is excited by an rf electric field. Clockwise and counterclockwise waves in the surface of the rotor interfere with each other adjacent the transducer to form a bridge system which produces a null when the waves are out of phase. The rf frequency of the electric field is varied to obtain the null and, thus, is a measurement of the rotation rate of the rotor.