GB449281A - Improvements in or connected with rangefinders, heightfinders, and like optical instruments for the measurement of angles - Google Patents

Abstract

449,281. Rangefinders &c. BARR & STROUD, Ltd., and STRANG, J. M., Caxton Street, Anniesland, Glasgow. April 18, 1935, No. 11970. [Class 97 (i)] Means for testing the adjustment of a single observer rangefinder &c. comprises, within the casing of the instrument, optical members for receiving light directed transversely from one side of the optical system of the rangefinder from, or as from, an object situated laterally on the prolongation of the base of triangulation, and for causing the light to produce in the field of view of each of the telescope elements of the rangefinder an image of the object which thus appears at a definite and constant range, which may be infinity. In Fig. 1, light from an external natural object enters the casing A by a window 5 and is directed by optical squares C to the reflecting prisms 3 of the instrument. The apparent range of the object can be varied by displacing a prism D. Instead of viewing an external object, a collimator may be used to project light to the squares C ; the collimator may be placed in the window 5 or in other positions in association with suitable reflectors. In Fig. 5, a collimator E2 is arranged within the casing and a reflecting prism F1 directs the light to the squares C. The collimator is mounted in a ring 6 so as to be adjustable about two axes at right-angles to each other by screws 8, 12.