GB614929A - Improvements relating to viewing devices such as gun-sights and camera view-finders - Google Patents

Abstract

614,929. Sighting devices. KODAK, Ltd. Feb. 11, 1946, No. 4237. Convention date, Nov. 28, 1944. [Class 92 (ii)] [Also in Group XX] In a sighting device of the type wherein an observer sees a distant graticule image superposed on a distant object by means of a partial reflector, the distant image is formed by several juxtaposed and identical collimators each comprising a graticule and a collimating element, the arrangement resulting in an extension of view finder's exit pupil. As shown in Fig. 1, the view finder may comprise a semi-reflector 21 through which an observer at 23 sees a distant object having superposed thereon a graticule image formed by reflection at 21 of the rays from the collimators comprising collimating lenses 25 co-operating with graticules 26 illuminated at 31. Such view finders may be incorporated in a photographic camera or gun-sight and, as shown in Fig. 6, for a camera, a view finder may comprise a semireflector 56, hinged about a horizontal axis, which reflects light to the observer from collimators comprising transparent blacks, the upper surfaces 71 of which constitute collimating lenses while graticules are engraved on the lower surfaces 70 ; the collimators receive daylight via a reflector 68. Other semi-reflectors may be used with the semireflector 21 in Fig. 1 ; these reflectors are placed parallel to one another and spaced in the direction of the collimator axis. Concave semi-reflectors may act as collimating elements co-operating with an equal number of graticules, the concave reflectors serving also to allow the distant object to be viewed. An arrangement is also described which allows of stereoscopic vision, the graticule image appearing either at infinity or at a finite distance, i.e. at the distance of the object; in this arrangement, the graticules and collimating lenses are provided on separate plates, which may be curved, so that the lines joining the optical centres of the collimating lenses with the centres, the graticules co-operating therewith converge to a point. A method of forming the graticules by photographing a master graticule through the assembly of collimating elements is also described.