US 4,063,799 AGranted

Photographic imaging

AssigneeTechnical Operations, Incorporated

InventorsKenneth L. Bernstein, Philip S. Considine, George B. Parrent, Jr.

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Abstract

This disclosure depicts an optical system and method for encoded storage and retrieval, wherein record images are enciphered using incoherent light and wherein deciphering of the coded images is performed in coherent light. More particularly, the disclosure depicts encoding images by inserting a complex phase function in the Fourier transform plane of the imaging means which satisfies the relation: .PHI.(x, y) = .PHI.(-x, -y). To retrieve a decoded image of the original object, the encoded record is illuminated with collimated coherent quasi-monochromatic light and its Fourier transform is formed in a plane in space. A complex phase function equal to the autoconvolution of the coding function is located in the transform plane. The phase-altered distribution in the transform plane is retransformed to produce a decoded image. Exemplary coding and decoding phase function is also depicted.

Claims3

Dependent claims

An optical method of coding and decoding comprising:

a. Illuminating an original object with incoherent light having a spectral width at least as narrow as 400 angstroms so that modulated light passes from said object;
b. Phase-shifting said modulated light in a Fourier transform plane according to a complex function having the property that only pi phase-shift differences are introduced between points introducing different phase-shift or the phase-shift introduced conforms with the symmetric functions .PHI.(x,y) = .PHI.(-x, -y) where:
.PHI.= the phase-shift introduced at each point and
x and y = Cartesian coordinates at each point
c. Making a visible recording of an image of said object containing aberrations introduced by said phase-shifting in an image plane;
d. Illuminating said recording with coherent collimated quasi-monochromatic light so that modulated light passes from said recording;
e. Phase-shifting the modulated light passing from said recording in a Fourier transform plane according to a complex function derived from the auto-convolution of the function used in making said recording;
and
f. Intercepting an image of said recording in an image plane with said aberrations removed.

6 more elements

Dependencies are inferred from the claim text.