| 摘要 |
An information-bearing laminar assembly, suitable for use as an identification card, is disclosed. The assembly is characterized by the provision therein of an embedded halftone image security feature that becomes visible essentially only when the assembly is view in transmitted light. The information-bearing laminar assembly comprises an inner information-bearing layer interposed between a first and a second light-transmissive protective outer layer. The inner layer contains both visible information-bearing indicia and an imagewise halftone pattern of laser-ablated microholes. The light-transmissivity of the information-bearing inner layer within said half-tone pattern is imagewise differentiated at each microhole as a function of the microhole's penetration depth. Sandwiched between the protective outer layers, the halftone pattern is imperceptible when the information-bearing laminar assembly is viewed in reflections and perceptible when the information-bearing laminar assembly is viewed in transmission.
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