| 摘要 |
<p>In order to provide comprehensive and multipurpose security, an optical security device comprises a substrate (10), and at least a first optically structured layer (14) which is such as to provide first, second and third optical inspection levels, namely a first inspection level (2) where a first optical property can be discerned with the naked eye, a second level (4) in which an object can be discerned with the aid of an optical inspection tool (26), and a third level (6) in which an encrypted object can be discerned with a decrypting optical inspection tool (20). The first layer (14) is constructed as a retarder plate of LCP material, having an array of elemental areas having different predetermined orientations.</p> |
