| 摘要 |
A data card (10) comprising a self-supporting, wallet size plastic card base (12) upon which is disposed a film substrate layer (22), a highly reflective layer (24) and an optical storage layer (26) which is a selected photosensitive layer which has been exposed at an actinic wavelength and developed to be substantially opaque over a portion of its extent, except for an imagewise exposure pattern of clear and partially clear data marks revealing to varying extents reflectivity in the underlying reflective layer. Data spots (17, 18, 19) may have one of four different reflectivities thereby representing a quadrinary digit 0, 1, 2 or 3 replacing two binary digits. The reflective layer is matched to the selected optical storage layer so that the reflective layer is highly reflective at a read beam wavelength in the read or near infrared and less reflective at actinic wavelengths either in the blue/green range or in the ultraviolet.
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