Ultrasonic irradiation system

摘要

Herein disclosed is a system for irradiating sound waves to be converged into an annular focal zone having a desired size. This system uses a transducer which is composed of a plurality of elements divided at least in a circumferential direction of the face of the transducer so that the phases of drive signals may be changed according to the respective circumferential positions of the oscillating elements to rotate the phases of the drive signals n rotations in the circumferential direction. As a result, the annular focal zone of having a desired radius is formed, and integrated values of sound waves in the circumferential direction may be substantially zero on the focal plane so that an unnecessary secondary focal zone is prevented from being formed.