GB573700A - Improvements in and relating to optical or like projectors - Google Patents

Abstract

573,700. Optical projectors. MARTIN, B. Sept. 14, 1943, No. 15074. [Class 97 (i)] An optical projector for the projection of screen images from a stationary kinematograph film comprises a casing 9, a film-carrier 32, an optical projection system which consists in a frontal truncated ellipsoidal reflector 1 and a rear spherical reflector 2 disposed so that the source of light 3 is placed at the focus of the frontal reflector and the centre of curvature of the rear reflector and a cooling cell 31 containing liquid positioned before and in close association with the film-carrier. An inner truncated ellipsoidal frontal reflector 4, alone or in association with an axially-disposed refracting system 5, may be used, and the reflectors may be sectored as described in Specification 567,154. The cooling cell, Fig. 2, has plates of glass or quartz 37 and 38 spaced apart in a frame 33, the space being filled with air-free water. A storage tank 36 is mounted above the cell and is connected thereto by pipes in such a manner as to give a thermosiphonic circulation, and a liquid-sealed breathing device is fitted, or a pump may be used to give forced circulation. A highly concentrated beam of light may be passed through the film, giving a long throw and high illumination without damage to the film. Specifications 267,171, 274,202, [both in Class 97 (i)], 340,522 and 360,910, [both in Group XI], are referred to concerning the optical system and 327,129, [Class 97 (i)], concerning the cooling cell.