Photonic crystal security device and method

摘要

A method of forming an optically variable security device is provided. In the method, a photonic crystal material is provided and a process is performed upon the material which causes deformation of the material so as to form a first region (A) for which incident light received by the crystal material is selectively reflected or transmitted to generate a first optically variable effect, and a second region (B) for which incident light received generates an optical effect, different from the first optically variable effect. Corresponding devices having first and second regions are also disclosed.

主权项

1. An optically variable security device comprising at least a first region and a second region that each region comprises a photonic crystal material, whereby:
in the first region the photonic crystal material is configured such that incident light received by the photonic crystal material is selectively reflected or transmitted by the photonic crystal material to generate a first optically variable effect when illuminated and viewed under a predetermined set of conditions; and in the second region the photonic crystal material is configured such that incident light received by the photonic crystal material is reflected or transmitted by the photonic crystal material to generate a second optical effect different from the first optically variable effect when illuminated and viewed under the same said predetermined set of conditions, wherein:
each of the first and second regions has a respective degree of crystal ordering; andthe degree of crystal ordering of the second region that generates the second optical effect is greater than or less than the degree of crystal ordering of the first region that generates the first optically variable effect.