New Method of Optical Processing Using a Random Diffuser

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Abstract
In this article we describe a new method of optical processing which is one of the principal topics of study in our laboratory. This consists of the detection of the difference between two images, the multiplexing of images, the contrast reversal of the reconstructed images in carrier frequency photography, the coding and decoding of a message and the reconstruction of colour images from black and white recordings. The signal, modulated by a random diffuser with high spatial frequencies, is recorded at least twice on the same photographic plate with a small displacement of the plate between the exposures. The required information can be extracted by spatial filtering of the spectrum of the recorded signals. This spectrum is modulated by a system of interference fringes which determines the nature of the filter. The recording can be done in white light whereas the reconstruction is made in the laboratory using coherent light.