| 摘要 |
An optical device comprises an encoding surface having a micro-relief pattern (22) over at least part thereof designed to produce a predetermined diffracted first image when illuminated in use, and an optically anisotropic layer (26) such as a polymerised liquid crystal provided whereby at least part of said micro-relief pattern (22) induces local orientation of said optically anisotropic layer (26) thereby to impose a predetermined polarization modulation, thereby to produce a predetermined polarization dependent second image when illuminated in use. |
