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.