GB581769A - Improvements in or relating to range finders - Google Patents

Abstract

581,769. Range - finders. KODAK, Ltd. July 13, 1942, No. 9742. Convention date, July 18, 1941. [Class 97 (i)] In a range-finder having a continuouslymoving view point, as described in Specification 581,765, provision is made whereby a second superposed image may be observed, and the range may be determined by coincidence ; a pair of such instruments may be combined so as to form a binocular instrument adapted for stereoscopic use. Fig. 2 shows a range-finder having a periscopic combination o<2> reflecting surfaces 45, 46 on a prism in a rotatable housing 44, the surface 46 being in front of an objective 42 forming an image in the focal plane of an eyepiece 40. A window is formed on the surface 46 by a cemented prism 48, and light from the object entering by an aperture 49 passes axially to the objective 42 and forms a second image in the eyepiece, superposed on the first. Approximate coincidence of the images of the range object may be produced while the housing 44 is stationary by axial adjustment of an optical wedge 50 operated by a scaled drum 60 ; an aperture 51 in the wedge 50 permits the passage of light from. the aperture 49. Accurate reading may be made by rotating the housing 44 and adjusting the wedge 50 until apparent relative movement of the two images of the range object, during, the rotation, is eliminated. Fig. 3 shows a modification comprising a doubly-reflecting prism 70 to increase the separation of the view points ; the wedge 74 comprises a central portion directed oppositely to the main portion. Other constructional embodiments are described, one being binocular, as described in Specification 581,767, and permitting use as a stereoscopic instrument.