Large-Screen Television Displays.

After reviewing the various requirements, such as brightness, screen area, resolution, contrast, which have to be fulfilled according to the kind of application, the author analyzes the large screen projection systems presently available on the market. These fall into two main types: projection systems using phosphor cathode ray tubes, and those, such as Eidophor, which are in fact light-valves based on the light diffraction due to the surface deformation of an oil film bombarded by an electron beam. Systems are then reviewed which are still at the laboratory stage. Two of them, which have already demonstrated their capabilities, are described in details in other articles of this issue: the Titus tube and the laser projectors. Other image light-valves are examined; some of them use the surface deformation of materials such as thin metallic membranes, elastomers and ferroelectric ceramics; others are based on the light scattering in materials such as ferroelectric ceramics and liquid crystals. Most of them seem better adapted to large or medium screen data display than to television picture projection.