Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1993-12-03
1995-10-24
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
235494, G06K 710
Patent
active
054612390
ABSTRACT:
An optical memory diffraction grating having a plurality of spaced ridges each having a plurality of optically reflective facets. When illuminated with an incident light beam the grating produces a number of diffracted beams corresponding to the number of facets. The diffracted beams can be machine read by a reading device which produces a reading light beam directed at the grating. The reading device has a plurality of detectors positioned to be illuminated by the diffracted light beams. Information can be stored in the optical memory by locally changing the optical properties of the grating. The grating may be employed in security cards and documents. The grating may be arranged as a bar code or as a pixelgram. Reading, writing and erasing devices are also claimed.
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Mikoh Pty Ltd
Nichols Steven L.
Westin Edward P.
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