Abstract: A small, simple, yet accurate probe for producing a sector scan for ultrasonic medical diagnostic apparatus is provided by positioning a curved transducer array within the probe opposite a window, and filling the probe with a fluid having an acoustic velocity on the order of 0.5.times.10.sup.5 cm/sec. This combination is made possible by forming the window from a stiff polyionomer material whose acoustic velocity is closed to that of human skin, yet which is stiff enough even when thin to be essentially non-deformable in clinical use. Grating lobes of the ultrasonic beam, as well as the scatter produced within the probe by the high reflectivity of the window material, are absorbed by coating or lining the inner side walls of the probe with an open-celled polyether urethane foam having a cell diameter slightly smaller than one wavelength of the ultrasound in the probe fluid.

Abstract: A simple, versatile switching system for ultrasonic transducer arrays uses in-probe concentration and a crosspoint switching matrix, both under the control of a microprocessor in the control unit. The number of crosspoints is kept to a minimum by connecting transducer elements to the pulse delay or receive delay lines in symmetrical pairs; and the high-voltage pulsing is done on the probe side of the switching matrix to allow the use of the same light-duty matrix for both pulsing and receiving.