GB581765A - Improvements in or relating to range finders - Google Patents

Abstract

581,765. Range-finders. KODAK Ltd. July 13, 1942, No. 9738. Convention date, July 18, 1941. [Class 97 (i)] A range-finder comprises a single objective, having an axis which is stationary at its image plane, means for continuously moving the effective view-point of the instrument along a path having a constant radius, and optical deflecting means in the light path through the instrument such deflecting means being adjustable to bring the image of the object ranged on into the axis of the objective ; when the stationary part of the objective axis is directed to the object ranged on, and the deflecting means is adjusted so that the image of such object is on the axis throughout the movement of the view point, the image of this object appears to be stationary while the images of all other objects are in movement, and the setting of the adjusting means when this condition exists provides an indication of the range of the object. Fig. 3 shows an objective 42 producing an image which is viewed by means of a roof prism 41 and eyepiece 40. The objective 42 is mounted coaxially in a tube 43 which is rotatable in bearings 47, 48, and carries a rotor 44 forming a housing for a prism having a periscopic combination of reflecting surfaces 45, 46. The rotor 44 may be turned by hand or by a motor, and produces a repetitive circular variation in the effective view point of the instrument. The instrument is directed with the rotation axis towards the object to be ranged upon, and the image of the object is brought to the rotation axis by deflecting means comprising an achromatic or other optical wedge 55 carried by a sleeve 56 constrained to turn with the tube 43 and axially slidable therein. The sleeve 56 is pressed by a spring 59 and is connected by a pin 57 to a collar 60 slidable outside the tube by a drum 67 engaging it through ball bearings 61.. The drum 67 is rotatable on a screw thread 64 and carries on its outermost surface a spiral scale readable against a fixed mark to indicate range. An optical wedge 72 before the reflector 46 enables infinity and other adjustments to be effected. The objective 42 may be located between the reflecting surfaces 45, 46 or in front of the surface 46. Several constructional forms of instrument embodying, in some cases, other light-deflecting means, a non- rotating objective and an eyepiece for reading the range scale, are described. In one construction the objective is combined with a wedge and is displaceable from the rotation axis for light-deflecting purposes. Specification 484,172 is referred to.