Stacking a visible image and a synthetic hologram
AssigneeCommissariat A L'energie Atomique Et Aux Energies Alternatives
InventorChristophe Martinez
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Abstract
A synthetic hologram of a first image consists of an array of coding cells each comprising light and dark portions. A second visible image is superposed to the synthetic hologram, where the light and dark portions of selected coding cells in the second visible image are inverted and have a phase modified by an offset value relative to other coding cells of the rest of the hologram.
Claims9
A synthetic hologram of a first image formed of an array of coding cells, each of which comprises light and dark portions, comprising a second visible image superposed to the hologram, formed on a portion of the hologram, in which the light and dark portions of selected coding cells of the hologram are inverted and have a phase modified by an offset value with respect to other coding cells of the synthetic hologram of the first image.
A method for manufacturing a synthetic hologram superposed to a directly observable pattern, comprising the steps of:
- computer manufacturing of an image Ih for the hologram;
- computer manufacturing of an image Im of the pattern,
- calculation of the Fourier transform (FT) of image Ih,
- coding of the amplitude of the FT by generation of a matrix A of aperture sizes,
- coding of the phase of the FT by generation of an aperture offset matrix P,
- generation of a first amplitude matrix A1 corresponding to the intersection between A and Im,
- generation of a first phase matrix P1 corresponding to the intersection between P and Im,
- generation of a second amplitude matrix A2 corresponding to the intersection between the inverted or negative representation of A and the complementary of Im,
- generation of a second phase matrix P2 corresponding to the intersection between matrix P, to which is added a phase shift f0, and the complementary of Im,
- gathering of matrixes A1 and A2 in a single matrix A′,
- gathering of matrixes P1 and P2 in a single matrix P′,
- lithography of a substrate with the generation of a matrix of apertures having sizes and positions defined by the two previous matrixes.
Dependencies are inferred from the claim text.