GB388754A - Improvements in or relating to colour photography and projection - Google Patents

Abstract

388,754. Colour photography and projection. HILGER, Ltd. A. and DOWELL, J. H., 98, Kings Road, Camden Road, London. Aug. 29, 1931, No. 24357. [Class 97 (i).] In the production of colour component images, particularly for kinematography, an imagedividing prism is combined w i t h cylindrical and spherical lens elements to produce two or more identical images from the same view-point, the images having different magnifications in the horizontal and vertical directions so that one set of companion images exactly fills one picture space on the film and the images are in close juxtaposition. In Fig. 1 the light is received by a cylindrical positive lens 12 and then enters a prism 1 having a semireflecting surface 3 dividing the beam into two parts, one of which after reflection by the surface 5 passes through a negative cylindrical lens 13 and a positive spherical lens 15, while the other is reflected at the surface 7, passes through lenses 14, 16 similar to the lenses 13, 15, and is deviated by a mirror 9, the images being formed side by side at 10, 11. The axes of the positive and negative cylindrical lenses may be parallel, or at right-angles, to each other, and the spherical lenses may be disposed between the cylindrical lenses instead of having the position shown. The spherical and cylindrical elements may be combined in such a way that at least one lens has a spherical face on one side and a cylindrical face on the other. The prism 1 may itself be provided with spherical or cylindrical surfaces instead of the plane entrance or exit surfaces shown. The images are projected on to a screen 22 through a system which corrects the distortion, such system consisting, for each image, of a spherical lens 23, Fig. 3, between cylindrical lenses 24, 25. The axes of the cylindrical lenses may be crossed, in which case the lenses are either both positive or both negative, or the axes may be parallel, in which case the lenses are preferably of opposite signs. Specification 349,107 is referred to.