| 摘要 |
The invention relates to a double-sided transparent security element (20) for protection of valuable objects having motifs in the form of patterns, characters or codings introduced into the security element, comprising a first optically active layer (24) composed of a cholesteric liquid-crystal material, which selectively reflects light with a predetermined circular polarization in a predetermined wavelength range, and a second (22) and third (26) optically active layer, which are arranged on both sides of the first optically active layer (24) and each form a phase-shifting layer for light from the predetermined wavelength range. The second and third optically active layers (22, 26) in this case contain motifs which are independent of one another, in order to verify the security element (20) from opposite sides. |
