| Popis: |
Optical textures in liquid crystals are due to the self-organization of molecules and can be easily obtained in a cell with simple alignment techniques. These optical textures usually have nonuniformity or randomness, and then each cell fabricated by the same process has the different pattern of the optical textures. This kind of randomness is not suitable to general applications. In the security systems, however, randomness plays an important role. We have proposed an application of photopolymerized nonunifonn liquid crystal films to security devices, which are embedded in the artificial materials requiring authenticity. The information read from these films should be unique due to the randomness and can be used as the identification information. |
