| 摘要 |
A method of producing a security document or device comprising a substrate a nd an optically diffractive device, the method comprising the step of: irradiating an area of the substrate (2) on one surface with patterned laser radiation to ablate selected portions of the surface and thereby form an optically diffractive structure in said one surface. A method of producing a security document or device comprising a substrate and an optically variable device, such as a means for creating polarisation patterns, the method comprising the step of: exposing an area of the substrate on one surface to a light source which causes photo-polymerisation of the substrate which in tur n produces a polarisation state or pattern. |
