GB1003886A - Optical systems - Google Patents

Abstract

1,003,886. Beacon lights. SENDLINGE OPTISCHE GLASWERKE G.m.b.H. Nov. 3, 1961 [Nov. 4, 1960], No. 39392/61. Heading F4R. A lens for aerodrome lighting or like purposes for producing beams of light leaving the lens surface at a small angle of emergence comprises a glass body having a substantially flat outlet face and a hollow inlet face surrounding but spaced from the light source, the arrangement being such that a first part of the light passes direct to the outlet face and a second part is reflected and crosses the first part on the way to the outlet face. The glass body may be designed for omnidirectional or bidirectional lighting. In one form light from the source L is formed into a parallel beam by a convex toroidal ring 3 and is refracted at the emergent face 14 at a small angle, e.g. 3 degrees to the horizontal. A second part of the light passes through a frusto-conical ring 5, and after reflection at a surface 6 which may be plane or parabolic, crosses the first beam of light and is refracted at the emergent face 16 at a similar small angle. The emergent face may be plane or the central part 16 may be surrounded by a slightly inclined ring 14. Alternatively, the central part 16 may be in the form of a concave conical surface of small inclination. The surface of the block inside the ring 3 may be formed with concentric grooves so as to refract the incident light to emerge from the outlet face at a small angle. Light which is internally reflected at the outlet face may be reflected by a face 13, re-reflected at the outlet face so as to pass back through the source L being then reflected by a spherical mirror 18. The face 13 may be formed with grooves so that incident light is reflected in a parallel path. The face 5 may also be a convex toroidal ring so as to produce a parallel beam. The light source may be surrounded by a coloured shell 17. In a bidirectional block, the toroidal face or faces may be replaced by convex cylindrical lenses.