| 摘要 |
<p>An optical storage medium 7 (provided in a credit card for example) e.g. a glass ceramic, the optical characteristics of localised regions of which can be selectively changed by conversion from an amorphous form to a crystalline form. Conversion may be, by a scanned modulated laser beam. Reading may be by scanning or flooding with light (including infrared/u.v. as appropriate). The optical material may be in strips or a spiral for example. Fig. 1 also shows printed data 2, signature strip 3, magnetic security strip 4, logos and security holograms 5, 6. <IMAGE></p> |
