GB232402A - Improvements in distance or range finders applicable also for use in military surveying and the like - Google Patents

Abstract

232,402. Eden, J. L. April 3, 1924. Range-finders.- Short-base coincidence rangefinders of the type described in Specifications 6537/13 and 22539/14 comprise a closed case 1 having openings or objectives 2, 3 in the front vertical wall, the reflecting prism 7 opposite the left-hand objective 2 being fixed, and the second prism 6 mounted in a frame 4 pivoted on the hypotenuse of the fixed prism 7. Rays entering the objective 2 are reflected by the prisms 7, 6 to the glass plate 13, the lower half of which is silvered, from which the rays are reflected and received in an eyepiece 10. This plate 13 is mounted in a frame 14 pivoted about an axis 15. Two range scale screws 20, 18 are provided for the adjustment of the frames 4, 14 respectively. The range scale is engraved on a screw 22 having a comparatively coarse thread so that the scale may be open and movement of the head 24 is communicated to the lever 4<x> of the frame 4 bv the finely screwed rod 25, the upper end of which is square and sliding in the screw 22. The lower end of the rod is pointed and screws into the base of the nut 21. This arrangement gives a small movement to the frame 4 and a greater movement to the range scale. Adjustment of the instrument for wear &c. is effected by the movement of a vertical glass plate 26, situated near the right hand objective 3, about an axis 28 by the screw 29 as shown, causing a slight deviation of the image formed by the rays entering the aperture 3. In a modification prisms 7 and 6 are dispensed with and the aperture 2 placed so that the rays from the object reach the mirror 13 direct. In this case only a single range screw is used.