| 摘要 |
<p>A holographic security device comprising first and second holographic generating structures (2, 3) recorded in respective sets of substantially non-overlapping regions of a record medium. The regions of one set are interleaved with regions of the other set, whereby both interleaved line structures are substantially non-visible to the unaided eye, whereby the holographic security device generates two or more holographic images (A, B) viewed from separate viewing directions around the device and normally seen by tilting the device. Each particular holographic image in a viewing direction is generated in whole or part by the holographic structure associated with one set of interleaved lines.</p> |
