| CPC B42D 25/378 (2014.10) [B42D 25/23 (2014.10); B42D 25/29 (2014.10); B42D 25/346 (2014.10); B42D 25/373 (2014.10)] | 15 Claims |
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1. A method of authentication, comprising:
forming a secure instrument comprising:
providing a polymer substrate having a first surface and a second surface and a first end and a second end,
coating the first surface of the polymer substrate with an inner layer, the inner layer being a conductive, absorbing, or upconverting layer and including one or more gaps therein, and
coating the inner layer with an opacity layer;
detecting, by a detector, an anisotropy associated with the one or more gaps of the inner layer; and
authenticating the secure instrument based on the anisotropy detected by the detector,
wherein the one or more gaps of the inner layer are configured as one or more unconnected lines, at least one unconnected line of the one or more unconnected lines extending across the polymer substrate from the first end of the polymer substrate to the second end of the polymer substrate.
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