GB1260660A - Method and apparatus for the production of a directly viewable stereoscopic image - Google Patents

Abstract

1,260,660. Uses of photochromism. AGFA GEVAERT A.G. 18 Dec., 1968 [18 Dec., 1967], No. 60204/68. Heading C4S. [Also in Divisions G2 and H4] In the production of directly viewable stereoscopic images a pair of stereoscopic pictures 10, 11 are illuminated with coherent light and recorded in superimposition on a common record carrier 12 as holograms, the angular rotation between the illuminating and reference beams being such that on illumination of the record carrying the holograms with a reconstructing beam of visible light, image bearing beams will emanate from both holograms simultaneously so that an observer can view the two pictures one with each eye. The two pictures 10, 11 are illuminated simultaneously. A coherent light beam from laser 1 is split at 2 to form object and. reference beams. The object beam isreflected by a mirror 3, split at 4 with the secondary beam reflected at 5, thus two beams following optical paths the centres of which are coincident with the centres of their respective picture, but which cross in the centre of the record carrier 12. The reference beam is refleeted at an angle to carrier 12 by a mirror 14 but is still superimposed on the object. beams. The holograms are reconstructed by a reconstructing beam following the same path as the reference beam, whereupon each eye 15, 16 of an observer sees one of the pictures. In an alternative embodiment the pictures 10, 11 may be replaced by two side-by-side film strips each exposure of which is consecutively illuminated with ultra-violet light to form a hologram on a photochromic surface, e.g. glass containing silver halides or plastics. Also the record carrier may be the screen of a television camera, the holograms formed thereon being converted to electrical signals which are fed to a scanning means 30 for reconstruction on a television viewing screen 31 which comprises a photochromic layer. The screen 31 is illuminated with ultra-violet light to build up the hologram pairs which are then illuminated with visible light from laser 32 to give visible images. A plurality of pairs of holograms are successively recorded on the screen 31, each preceding pair being erased by a burst of infra-red radiation.