Computer generated holographic microtags
AssigneeSandia Corporation
InventorWilliam C. Sweatt
Life of this patent
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Abstract
A microlithographic tag comprising an array of individual computer generated holographic patches having feature sizes between 250 and 75 nanometers. The tag is a composite hologram made up of the individual holographic patches and contains identifying information when read out with a laser of the proper wavelength and at the proper angles of probing and reading. The patches are fabricated in a steep angle Littrow readout geometry to maximize returns in the -1 diffracted order. The tags are useful as anti-counterfeiting markers because of the extreme difficulty in reproducing them.
Claims21
A microtag for placement on an object comprising a microscopic computer generated hologram comprising an array of individual phase grating patches in a diffractive Littrow readout geometry with feature spacings between the individual diffractive elements in the patches in the array being a value of between about 250 nanometers and about 75 nanometers.
A microtag for placement on an object comprising a microscopic computer generated hologram comprising an array of individual phase grating patches in a diffractive Littrow readout geometry optimized to return light from the microtag in the -1 diffracted order with feature spacings between the individual linear diffractive elements in the patches in the array being a fixed value of between about 250 nanometers and about 75 nanometers.
Dependencies are inferred from the claim text.