Security label which is optically read by terahertz radiation

Abstract

The present invention relates to security label (12) for securing or authenticating goods or services or a security document. Currently radio frequency ID cards, having an inductive loop and a microchip containing security information, are used. However, such RF ID cards are expensive to manufacture. Therefore it is proposed to use a security label or document (12) including a terahertz image or tag (14, 15, 76) which may beta hologram. Security information can then be read by reflection or transmission of terahertz radiation which is not visible to the unaided eye. The terahertz image or tag may be covered by a material (66, 68) opaque to visible light, but transparent or transmissive of terahertz wavelengths, making it difficult for potential fraudsters to investigate the terahertz image. A method of making such a security label or document, a security or authentication method and system using terahertz radiation are also disclosed.

Dependencies are inferred from the claim text.