GB265177A - Improvements in reflectors for a point-like source of light - Google Patents

Abstract

265,177. Zeiss, C., [Firm of]. Jan. 27, 1926, [Convention date]. Reflectors.-In a reflector for an oblong field of illumination employing a substantially point source of light, the reflecting surface is neither a surface of revolution nor cylindrical i.e. it is such that at any point the radius of curvature in any direction is different from the radius of curvature in any other direction and all these different radii are of finite length and it is subdivided by a plurality of surfaces into step-like zones each of which is related to a zone of the field to be illuminated and which are so formed that the illumination of the field changes from zone to zone according to any desired requirement. Figs. 1 and 6 illustrate two of the three examples described. In the first the zones a<6>, a<5>, &c., are defined by parallel planes, in that of Fig. 6 the plane surfaces defining the zones l<1> - - l<12> converge to a common straight line containing the light source and perpendicular to the main axis of the reflector. The third form resembles the last, but the main axis of the reflector coincides with the line common to the converging planes. All direct light is intercepted by an inverted spherical reflector i. Fig. 7 shows the reflector of Fig. 6 in use for providing a uniform field of illumination in a street. The luminous fields of adjacent reflector zones overlap to a small extent.