GB1290577A - - Google Patents

Abstract

1290577 Projecting coloured images POLAROID CORP 24 Feb 1970 8831/70 Heading G2J A scene recorded upon an image carrier as an array of regularly spaced colour components R 1 -R 3 Fig. 2 arranged in serially repetitive fashion is projected in magnified form to an image plane 26 through an objective 24 and diffraction grating 28 arranged to diffract the projected image to form at least zero and selectively spaced first order images at said plane 26 wherein substantially any zero order colour components of one of the images has superposed upon it a first order component image of a different colour whereby the array of colour components are caused to blend additively. The diffraction grating may be an amplitude transmission diffraction grating, a fully transmissive pulsed phase grating or comprise a medium of sinusoidally varying optical thickness interposed in the optical path. The gravity is located to form a transhoper diffraction pattern, and where a sinusoidal grating is used this may be formed on an optical surface of a lens in the projection system. The frequency of the grating (e.g. of periodially recurring opaque and light transmisive portions) is selected to cause an order image spacing such that any first order image has superimposed upon it and the first order image of the same colour.