| 摘要 |
In order to provide comprehensive and multi-purpose security, an optical security device is provided that comprises a substrate and at least a first optically structured layer. The optical security device may provide first, second and third optical inspection levels, including a first inspection level where an optical effect can be discerned with the naked eye, a second level in which an object can be discerned with the aid of an optical inspection tool, and a third level in which an encrypted object can be discerned with a decrypting optical inspection tool. The first layer may be constructed as a retarder plate of LCP material, having an array of elemental areas with different predetermined orientations.
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