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Optical Engineering

Hiding techniques to enhance anticounterfeiting capacity of dot-matrix holograms
Author(s): S. L. Yeh
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Paper Abstract

The images on a dot-matrix hologram consist of many 2-D grating dots with different pitches and orientations. Only some specified pitches and 256 specified orientations are usually employed. The difference between any two pitches to show different colors is more than 0.1 µm; therefore, it is possible to hide several extra pitches in a specified pitch. If all the extra pitches are almost equal to the specified pitch, grating dots with extra pitches will be of nearly the same color as the specified pitch. When a laser beam is incident on the dot-matrix hologram with hidden pitches, data for the hidden pitches will be decoded by the diffraction pattern of the grating dots of the hologram. A specified grating orientation can be used to hide extra grating orientations similarly. What's better, mixing the above two hiding techniques is possible.

Paper Details

Date Published: 1 August 2005
PDF: 6 pages
Opt. Eng. 44(8) 087001 doi: 10.1117/1.2032107
Published in: Optical Engineering Volume 44, Issue 8
Show Author Affiliations
S. L. Yeh, Lunghwa Univ. of Science and Technology (Taiwan)

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