Three-dimensional cathode-ray tube displays
E.A. Parker, P.R. Wallis · The journal of the Institution of Electrical Engineers. Part 3, Radio and communication engineering · 1948
The display of three-dimensional information is considered with particular reference to a radar system in which a narrow pulsed beam of radio-frequency energy is used to explore automatically a volume of space. The three-dimensional displays are used to display the positions of the reflected “signals” with respect to the three co-ordinates of the volume, in order that the radar can be used as an object-detecting and -locating system in three dimensions.In the past, “configurational” methods have been used, wherein the shape of the intensity-modulated echo-trace on the cathode-ray tube is altered to add a third variable to the two already provided by the c.r.t. deflections. These types are not discussed, attention being concentrated on other methods.The “truly three-dimensional displays” utilize a mechanical motion to add a third dimension to the screen of the cathode-ray tube, the picture appearing as an actual volume. The “perspective displays” simulate the same picture as in the previous display without any moving mechanisms, rotation of the volume and/or stereoscopy being used to give the impression of three dimensions. The “oblique displays” obtain the required three co-ordinates by combinations of two or more two-co-ordinate pictures on the same cathode-ray tube. The “polychromatic displays” use colour to represent a spatial co-ordinate.The physiological and psychological problems of the human operator peculiar to three-dimensional displays are discussed, and a Section is included on the relative advantages of “true” and “relative” displays. Another Section on “display sensitivity” leads to the general theoretical considerations involved in three-dimensional displays. The application of three-dimensional displays to other fields, for example X-ray photography, is briefly discussed.The revised form of the radar equation for use with three-dimensional displays is given in an Appendix.