Security label which is optically read by terahertz radiation

• US 20060231625A1
• Filed: 03/12/2004
• Published: 10/19/2006
• Est. Priority Date: 03/12/2003
• Status: Abandoned Application

• Current Assignee: The University Court Of The University Of Glasgow
• Original Assignee: The University Court Of The University Of Glasgow
• Inventors: Cumming, David R., Drysdale, Timothy D.
• Application Number:
  US10/548,529
• Publication Number:
  US 20060231625A1
• Time in Patent Office: Days
• US Class Current: 235/454
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G03H 2001/0016 Covert holograms or holobjects requiring additional knowledge to be perceived, e.g. holobject reconstructed only under IR illumination microholograms G03H2230/10
• CPC Class Codes: G03H 5/00 Holographic processes or apparatus using particles or using waves other than those covered by groups G03H1/00 or G03H3/00 for obtaining holograms; Processes or apparatus for obtaining an optical image from them G03H1/22 takes precedence; construction of electron microscopes H01J37/26; investigating or analysing materials by the use of microwaves G01N22/00, by the use of particles wave or X-rays G01N23/00, G21K7/00
• CPC Class Codes: G06K 19/16 the marking being a hologram or diffraction grating
• CPC Class Codes: G07D 7/0032 using holograms

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.

Claims

1. A security label or document that includes one of a terahertz image and tag.

2. A security label or document as claimed in claim 1, wherein the terahertz image comprises a hologram.

3. A security label or document as claimed in claim 1, wherein the terahertz image is sensitive to the wavelength of the illuminating radiation.

4. A security label or document as claimed in claim 1, wherein the terahertz image comprises a fractal structure.

5. A security label or document as claimed in claim 1, wherein the terahertz image comprises a frequency selective surface.

6. A security label or document as claimed in claim 1, wherein the terahertz image is adapted to transmit terahertz radiation.

7. A security label or document as claimed in claim 1 wherein the terahertz image is adapted to reflect terahertz radiation.

8. A security label or document as claimed in claim 1 wherein the label is laminated.

9. A security label or document as claimed in claim 8 wherein the terahertz image or tag is formed or defined in one of the layers of the label.

10. A security label or document as claimed in claim 9, wherein the layers of the label comprise at least one of paper, plastic and ceramic.

11. A security label or document as claimed in claim 1 wherein a plurality of terahertz images or tags are provided.

12. A security label as claimed in claim 1 wherein the terahertz image or tag is encapsulated or enclosed or laminated within a material that is transparent to terahertz radiation, but opaque to visible radiation.

13. A security label or document as claimed in claim 1 wherein the label is flexible.

14. A security label or document as claimed in claim 1 wherein the label is rigid.

15. A security label or document as claimed in claim 1, wherein the terahertz image is defined using at least one of wires, punched foil and any other metallic or dielectric medium that can be patterned to provide an image forming contrast.

16. A security label or document as claimed in claim 1, wherein the terahertz image is formed in any one of polycarbonate, polymethylmethacrylate, polystyrene, epoxy, polyethylene, Teflon, nylon, polyvinylchloride, polyaniline, poly (3,4ethylenedioxythiophene), alkyd resins, phenolic, polaymide, polyanhydride, polyimide, polyurethane, resorcinol, silicone and urea resins or any other mouldable plastic.

17. A method for making a security label or document comprising embedding or enclosing a terahertz image within a main body portion.

18. A method as claimed in claim 17, further involving forming the terahertz image.

19. A method as claimed in claim 18, wherein the step of forming the terahertz image is done using hot-embossing techniques or by etching.

20. A method as claimed in claim 17 wherein the step of embedding or closing the terahertz image involves encapsulating the image within an opaque material.

21. A method as claimed in claim 20, wherein the opaque material comprises a ceramic or polymer based material.

22. A method as claimed in claim 17, wherein the step of embedding or enclosing the terahertz image involves including the image in a laminated structure.

23. A method as claimed in claim 22, wherein the laminated structure comprises layers of at least on of paper, plastic and ceramic.

24. A method as claimed in claim 23, wherein said layers are opaque.

25. A security or authentication method for determining secure information on a security label or document and/or authenticating a security label or document, the method comprising:

irradiating the label or document with terahertz radiation ; and

detecting radiation either transmitted or reflected from the label or document, thereby to perform at least one of;

(i) determining secure information contained in the label; and

(ii) authenticating the label.

26. A method as claimed in claim 25 further involving decoding the secure information to provide it in a human readable or legible format.

27. A security or authentication system for determining secure information on a security label or authenticating a security label, the system comprising a source for irradiating the label with terahertz radiation;

a detector for detecting radiation either transmitted or reflected from the label; and

means for using the detected radiation to perform at least one of;

(i) determining secure information contained in the label; and

(ii) determining the authenticity of the label.