An improved three-dimensional display system.

Abstract Ultrasonic scans are taken in the usual way in a number of planes a regular distance apart, say 1 cm. These are transferred through the optics of the device onto a single film or plate in the form of small transparencies. Through the same optics, now working backwards, using stroboscopic illumination, the transparencies are projected onto a set of ground perspex screens mounted along a helix on the circumference of a rotating drum. Each component image is thus formed in the right position relative to the others. Images of different depths can be formed in different colours improving discrimination. Brightness of the images of different depths is variable independently of the others, further improving discrimination. The angle of viewing is extremely wide. None of these advantages can be achieved by holography.