A Simple Radiation Pressure Float for the Measurement of Ultrasonic Output

Abstract

A simple radiation pressure float can be used to measure the gross acoustic power beamed upward into a body of liquid by a transducer having lateral dimensions that are large compared to a wavelength. This float balances the upthrust of acoustic radiation force against the downward force of gravity, assuming an equilibrium position of partial immersion in the liquid. The preferred design eliminates any need for external guides or constraints: the float is self-centering. Criteria for a successful design are set forth. The interpretation of radiation pressure measurements is discussed briefly.