GB191118616A - Improvements in and relating to Range Finders and the like. - Google Patents

Abstract

18,616. Marks, E. C. R., [Dyer, R. E. H.]. Aug. 17. Range-finders. - Relates to binocular rangefinders, with which ranges are intended to be measured by the apparent displacement between marks or scales in the focal plane of an object glass or glasses respectively. In one form, Fig. 2, an instrument as described in Specification 12,238/10 is made either with a single object-glass c<1> covering both eyepieces b, or if two or more object-glasses are employed, the one nearest the eyepieces covers both of the latter. Alternative positions nearer to the eyepieces are indicated in dotted lines at f, g. A single hair-line &c. is placed in the centre of the focal plane and the eyepiece axes are arranged to converge upon the line, the images presented to the observer's eyes separately being staked to be as shown in Figs. 3 and 3<a>, and the binocular effect as in Fig. 3<b>, the object being represented by the cross; the apparent displacement shown in Fig. 3<b> is to be measured by a travelling arrow moved by a micrometer screw into apparent coincidence with one of the lines seen. In another construction shown in Fig. 12, the entrance prisms are carried on pivoted arms d, which can be folded together for transport, and the object-glass k and eyepieces b on a main central portion. A triangular prism u is provided for reflecting the rays from the extreme prisms into the eyepieces. Lenses i and may be used in addition to or in place of the object - glass k, the eyepiece axes being parallel when using the latter arrangement, with which similar scales may be used in each eyepiece instead of a single line, the scales being stated to appear to slide over each other and the apparent displacement to be a measure of the range. The distance between eyepieces is adjusted by moving the prism u longitudinally and so moving laterally or angularly the eyepieces which are connected with the prism-carrier by pins engaging in grooves in the carrier. The arms d carrying the prisms d may be arranged at various angles, other forms of entrance and central prisms, which can all be cut from the same piece of glass, being also employed. An objectfinder for the range-finder shown in Fig. 2, comprises a right-angled prism 19 with a portion of the face turned towards the observer covered by a mirror, the image of the pupil of the observer's eye in the mirror being brought into line with the reflection of the object in the prism 19.