| 摘要 |
A laminar postcard with hidden information consists of the sheets of paper or paper and photograph, in which the information in the form of inscriptions, images applied by printed or other method is hidden. In this case the surface of sheets, on which hidden information is applied, along entire surface glued between them, and visual perception of hidden information is achieved only in the environment of visible spectrum of light of increased intensity, which rays are directed from the luminous source toward the eye of observer through the postcard.
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