Patent ID: 7898648

Claim:
Optical identifier for generating an identification signal in response to an incident radiation beam, said identifier comprising: a carrier layer at least partially transparent to said radiation beam, wherein said carrier layer is covered with a protective layer, wherein said carrier layer has a first scattering face comprising a plurality of randomly oriented partial faces for scattering at least a part of said radiation beam, said identification signal being formed by said part of said radiation beam scattered traversing said carrier layer, a reflective face for at least partially reflecting a part of said radiation beam scattered by said first scattering face to said first scattering face, wherein said carrier layer has a second scattering face, opposite said first scattering surface, said second scattering surface comprising a plurality of randomly oriented partial faces for scattering at least a part of said radiation beam, a semi-transparent coating at an interface between said carrier layer and said protective layer, wherein said semi-transparent coating is adapted for a part of said incident radiation beam being reflectively scattered by said first scattering face having an intensity substantially equal to the intensity of a part of said radiation beam which traverses said carrier layer, said radiation beam being reflected by said reflective face or said second scattering surface and traverses said carrier layer again.