GB508219A - Improvements in or relating to illuminating means for optical projection - Google Patents

Abstract

508,219. Optical-projection apparatus. ZEISS IKON AKT.-GES. Jan. 5, 1938, No. 328. Convention date, Jan. 27, 1937. [Class 97 (i)] An illumination system includes a condenser 2, 3 forming an image of the illumination field 1 at the picture window 4 and two lenticular screens 5, 6, the arrangement being such that a plurality of images of the illumination field are formed in the plane of the screen 6 which is further from the light source, whilst images of the elementary lenses of the screen 5 are formed at the window 4. The lenses of the screens may be rectangular and arranged in columns and rows crossing one another at right angles and the screen 6 may comprise a honeycomb arrangement of hexagonal lenses. The screens may be formed on two glass plates forming the sides of a cooling bath or may be united with a thick glass plate. The system may be employed with any light source and may be added to any projection system provided it is placed at the appropriate distance from the picture window. A mirror condenser may be employed or a mirror-lens condenser, when the screens may be placed between the mirror and the lens of the condenser. A field lens may be arranged at the picture window to form an image of the screen 6 at the projection objective, particularly for use with lenticular films. The invention may be applied to cinematographic projection.