Electronic scanning in ultrasonic imaging using a wedge transducer.

The position-dependent resonant frequency of a wedge transducer is used to obtain electronic scanning of an ultrasonic beam by varying the frequency. A theoretical calculation of the resolution using the staircase model is in good agreement with the experiment. The principle has been applied to ultrasonic imaging both by combining the wedge transducer with a cylindrical lens and by direct emission into water. A higher resolution is obtained in the latter case, in agreement with the theory. Such a system is proposed as a rapid real-time imaging system for applications not requiring high resolution.