GB1321303A - Optical systems - Google Patents

Abstract

1321303 Optical apparatus PILKINGTON P E Ltd 28 May 1971 [31 March 1970] 15042/70 Heading G2J An optical system comprises a convex reflector 1, concave reflector means 2 arranged to focus incoming light at or near the convex reflector 1, and to receive light reflected from the convex reflector, a polarization sensitive beam-splitter 3 adapted to transmit light polarized in one direction and to reflect light polarized in the orthogonal plane, and polarization modifying means, e.g. a quarter wave plate 4, disposed between the beam-splitter and the concave reflector means so that light transmitted through the beam-splitter towards the concave reflector means is returned to the splitter polarized for reflection, and light reflected by the beam-splitter is returned polarized for transmission, the beam-splitter 3 and the concave reflector means 2 being so disposed that light travels via the splitter to the concave reflector means and reflected therefrom via the splitter to the convex reflector, and light reflected from the convex reflector travels via the splitter to the concave reflector means, and is reflected therefrom via the splitter to form an outgoing beam. This system may be used in a fog simulation device wherein an image of about unity magnification is produced, and the image is altered at or adjacent the convex reflector, as by a film, or by using a movable or semi-transparent convex reflector, or by lighting the front of the reflector. The concave reflector means may comprise a second concave reflector and quarter wave plate, when a quarter wave plate is provided between the splitter and the convex reflector Fig.2, (not shown). A second beam-splitter and a cube-corner reflector may also be provided Fig.3, (not shown), together with a doublet lens to correct spherical abberation of the mirror system.