The ultrasound camera—recent considerations

Abstract

The future of the ultrasound camera depends on improving its resolution: present camera tubes offer only a coarse picture (45 lines). This is nevertheless fine enough to display the 2000 bits of information which is the most the ultrasonic converter end-plate in present tubes can supply. Mechanical strength is the limiting factor. The plate is cut to be half a wavelength thick so as to resonate in sympathy with the incident ultrasound. Under these circumstances the point resolution on the plate face is about half a wavelength: greater resolution calls for higher frequencies and thinner plates but plates soon become too thin to be self-supporting. Other developments are linked to optical scanning, to the use of phase-sensitive detection for examining thickness changes and the flow in fluids and to pulsed ultrasound for displaying thick objects at chosen depths. This paper is based on the author's contribution to the symposium “Acoustic imaging and pulsed light” organized by the Mine Advisory Committee of the National Academy of Sciences at Berkeley, California, in December 1964