Improvements relating to screens for stereoscopic projection

570,594. Stereoscopic projection apparatus. BRITISH THOMSON-HOUSTON CO., Ltd., and CASTELLAIN, A. P. July 13, 1943, No. 11341. [Class 97 (i)] In a parallax-stereogram projection system, in which multiple images are projected through a line screen 4 on to the rear of a transparent screen 1, and are viewed through a corresponding front screen 5, the lines or strips of the screen 5 are formed to provide a regular recurrence of elements lying in more than one plane parallel to the image, thereby giving a stereoscopic effect to spectators at different distances from the screen. As shown, the strips 5 are of zig-zag form in a plane perpendicular to the surface of the screen. They may be formed of crimped strips of metal held in tension in a frame 6 and secured to transverse wires. Alternatively, each strip may be formed of discontinuous elements located in different planes.