GB603474A - Improvements in or relating to range finders - Google Patents

Abstract

603,474. Range-finders. KODAK, Ltd. Dec. 20. 1945, No. 34568. Convention date, March 13, 1943. [Class 97 (i)] In a coincidence or stereoscopic range-finder in which images from the ends of a base are formed in a comparison plane or planes by an optical system including a light deviator for effecting coincidence or stereoscopic fusion of the image, an adjustment mark is located in each plane or planes and an image of one mark is formed adjacent the other by the optical system of the finder, excluding the light deviator, so that non-coincidence of mark and image indicates maladjustment of the instrument. The coincidence finder shown comprises end prisms 10 from which images are formed in the plane 20 of an eyepiece 13 by lenses 11 and crossed prisms 12, a deviator 15 effecting coincidence. The plane 20 carries two diamondshaped marks and a vertical line. The latter is illuminated by a lamp 18, light from which passes via the right-hand objective 11 and prism 10 to a small prism 21 whence it is directed via a similar prism 22 and the other optical system to form an image in the plane 20 which, when the instrument is correctly adjusted, falls between the two marks. The marks may be carried on a plate separate from the eyepiece and observed by an independent observer. A stereoscopic finder is also described in which the image of a line in one comparison plane is formed adjacent two marks in the other plane by a similar prism system.