FEASIBILITY OF A MECHANICAL WAVE-GUIDE TO CONTROL THE ULTRASONIC-FIELD OF A PULSED PLANAR PISTON TRANSDUCER

An important consideration in the use of ultrasound in biomedical appl ications is controlling the range and spatial resolution. In this stud y, the feasibility of using a mechanical waveguide to control the axia l range of a flat disk transducer is considered. The waveguide is a wa ter-filled, circular glass cone fixed to the transducer. Experimental beam measurements are compared to theoretical predictions for transduc ers with and without waveguides. The results confirm that mechanical w aveguides may be used to control the axial location of the natural foc us and reduce the beamwidth at the focus and beyond. They provide a re latively inexpensive alternative to phased arrays and more flexibility than single-element transducers, as different sized waveguides would allow a single transducer to operate at a variety of axial ranges and spatial resolutions. (C) 1996 Acoustical Society of America.