| 摘要 |
A counterfeit-resistant document (10) comprises a substrate (22) and a nano-pattern (32) of nano-structures (38) disposed on the substrate (22), wherein the nano-pattern (32) is configured for forming a latent message (24) (e.g., a warning or alert message) that appears on a copy (20') of the document (20). The nano-pattern (32) forms one of a foreground (28) and a background (30) of the latent message (24); and another pattern, e.g., a conventional pattern (30) or another nano-pattern, forms the other of the foreground (28) and background (30) of the latent message (24). The nano-pattern (32) and the other pattern are configured, such that the foreground (28) and background (30) exhibit substantially similar visual densities on an original of the document, and exhibit substantially different visual densities on the copied document (20').
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