White Light Colour Photography for Rendering Holoimages in a Diffractive Screen

Abstract

The capability of color encoding the continuous sequence of views from a scene was demonstrated previously by the author (1990). In the present work, the scheme for this process is shown where white light from a black and white object is diffracted at a diffraction grating and then photographed on colour film. Two rays of different wavelengths reaching the plane of the color photographic film determine the stereo representation of an object point. Since the wavelength may have any value within the continuous visible spectrum, this case constitutes a new situation of continuous stereo photography. A natural process of decoding is represented where a diffusing white light source was added from the side of the developed photographic film. One white light ray that matches the former position of an incident ray receives the spectral characteristics of the registered point when traversing the photographic slide. It characterizes a situation of light path reversal, and the ideal result corresponds to a projected white light point being focused at the original object position. This situation generates a pseudoscopic image of the object, as seen from a certain distance, whose colour depends on the horizontal position of the observer.