An optically readable media (10) has an information-encoding layer (16)
and at least one color-forming layer (12) that embodies an optical readout-limiting
mechanism. In a first embodiment the at least one color-forming layer contains
an additive that does not interfere with the optical readability of the media for
a duration of a readout period. The additive, upon exposure to a source of optical
radiation that is suitable for reversing the color-forming layer from an optical
readout inhibiting state to an optical readout enabling state, undergoes a transformation
that maintains the color-forming layer in the optical readout inhibiting state.
More specifically, exposure to the source causes the color-forming layer to photobleach
and the additive to oxidize, where the oxidation of the additive permanently inhibits
the optical readability of the media. The additive may be a leuco dye. In one embodiment
the color-forming layer is comprised of 3-[2,2-bis(4-diethylaminophenyl)vinyl]-6-dimethylaminophethalide
and the additive is comprised of benzoyl leucomethylene blue. In a further embodiment
the additive is placed into a protective layer (18) that overlies the color-forming layer.