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US 9,789,724 B2Granted
Optical security device and system and fabrication methods thereof
AssigneeOpthentic Corp.
InventorsYingqiu Jiang, Aharon Hochbaum
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Abstract
The present invention relates generally to an optical security device and an optical security system in which hidden images that are invisible to the naked eye under unpolarized illumination, become visible under either linearly or circularly polarized illumination. Preferred fabrication methods of said optical security device are disclosed.
Claims8
A method of making an optical device containing patterned anisotropic phase retardation elements by a selective surface modification of a single cholesteric liquid crystal polymer (CLCP) layer, said method comprises the following steps:
- step 1—coating a CLC mixture on a substrate to form a CLC layer;
- step 2—partially polymerizing the entire said CLC layer by exposing it to ultraviolet radiation to form a CLCP layer;
- step 3—optionally surface modifying the entire said partially polymerized CLCP layer in a first direction at the CLCP-air interface;
- step 4—surface modifying said partially polymerized CLCP layer at the CLCP-air interface in selected areas in a second direction or in a plurality of other distinct directions;
- step 5—completely polymerizing said partially polymerized and surface modified CLCP layer;
- and
- step 6—applying a top coating onto said surface-modified and completely polymerized CLCP layer at the CLCP-air interface.
4 more elements
Dependencies are inferred from the claim text.