GB210411A - Process of and apparatus for exhibiting stereoscopic shadowgraphs or silhouettes - Google Patents

Abstract

210,411. Hammond, L. Jan. 23, 1923, [Convention date]. Optical-projection apparatus.-Two shadows of an object are cast on to a screen by two light sources, and means are proxided whereby the left eye of a spectator sees one shadow only and the right eye sees the other shadow only, the effect produced being that of one shadow located between the screen and the spectator. As shown diagrammatically, light sources 11, 12, at a distance apart corresponding to the interpupillary distance, cast shadows of objects 13, 14 on to a screen 10. Red and green or other complementary colour filters 16, 17 are provided in the light beams, and filter holders in the form of spectacles having red and green filters 18, 19 respectively are worn by the spectators so as to cause the shadows to appear at the positions shown in broken lines. Movement of the objects causes apparent movement of the shadows without variation in their size. In a modification, the colour filters are dispensed with, and rotating shutters are provided to obstruct the light beams and the view of the spectator, such shutters being synchronouslv rotated so that the left eye sees only the shadow cast by one light source and the right eye sees only the shadow cast by the other light source.