| 摘要 |
An optical media device comprises a mask layer placed over a data layer, and that includes chemical ingredients designed to render the data layer unreadable by an optical reader in a first initial state, and allow the data layer to be read when converted to a second state. The mask layer is optically opaque in the first state, and is optically transparent in the second state. The chemical ingredients include a dye that absorbs light in the visible light and/or optical reader spectrum, and a further chemical that is activatable to shift the dye's absorption wavelength so the data layer can be read by the optical reader. The activation source is radiative emission having a wavelength different from that of visible light and/or the optical reader. The activation source can be used at the point of sale of the device to render the device readable upon purchase.
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