Optical identification system using cholesteric liquid crystals

Abstract

Provided is an economical identification system suitable for use on commercial products which is difficult to duplicate, and highly identifiable. The system includes an identification medium having a high-polymer cholesteric liquid crystal material applied thereon. The high-polymer cholesteric liquid crystals selectively reflect a certain wavelength, and this wavelength changes with the change in the incident angle of the light. The liquid crystals also have the property to circularly polarize the reflected light in either sense. By taking advantages of such properties, it is possible to provide a highly identifiable structure which, however, is highly difficult to illicitly duplicate. In particular, by forming the reflective layer of a hologram with high-polymer cholesteric liquid crystals, the hologram can be used as an identification medium which is highly difficult to duplicate but easy to identify with a machine.

Dependencies are inferred from the claim text.