GB551391A - Improvements in or relating to variable power telescopes - Google Patents

Abstract

551,391. Telescopes; optical systems. PHILIPS LAMPS, Ltd. (Naamlooze Vennootschap Philips' Gloeilampenfabrieken). March 9, 1942, No. 3089. [Class 97 (i)] A high-magnification reflecting telescope and a low-magnification finder telescope have a common eyepiece, the image produced by the reflecting objective being presented to the eyepiece by means of a plurality of reflectors of which at least one is movable from its operative position. As shown, a spherical reflector 10, having a lens 11 to eliminate spherical aberration, forms the objective of the telescope, and, by means of mirrors 17, 18, 19, its image is formed at F<SP>13</SP> within the finder telescope. The finder has a lenticular objective 13, a magnifying erecting lens 14, and a focusable evepiece 24. The mirror 19 may be small and light, and be movable to the operative position, against the action of a spring, by means of a Bowden cable. The whole instrument is adjusted so that a graticule 23 limits the part of the image produced by the lens 13 which is to be examined with high magnification, and the mirror 19 is then moved into operative position for the purpose. The reflector 10 may be the metallized concave surface of. a spectacle lens having a focal length of 50 cms., and the lens 11 may be spherical and meniscus, e.g. a spectacle lens may be placed at the focus of the reflector 10, and may have a power of -0.25 dioptres. The lens 11 may be omitted, may, alternatively, comprise more than one lens, or may have a curvature on one surface of an order higher than the second order, and be made of gelatinisable or other material other than glass, e.g. as described in Specification 550,644. One or more of the mirrors 17, 18, 19 may be replaced by a reflecting prism surface.