Security device
AssigneeDe La Rue Holographics Limited
InventorsBrian W. Holmes, Kenneth J. Drinkwater, David Ezra, Jon Andreassen
Life of this patent
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Abstract
A security device includes first and second diffractive structures contained within a surface relief structure. The structures are such that the device responds to illumination at a first, visible wavelength to generate a first, visible pattern while any pattern generated by the second structure is not substantially visible at that wavelength, and the device responds to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading while any pattern generated by the first structure is substantially suppressed relative to the machine readable pattern at that wavelength.
Claims19
A security device comprising first and second diffractive structures contained within a surface relief structure, the surface relief structure being responsive to illumination at a first, visible wavelength, by a white light source, to generate a first, visible pattern, wherein all patterns generated by the second diffractive structure are not substantially visible at the first wavelength, and the surface relief structure being responsive to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading, all patterns generated by the first diffractive structure being substantially Suppressed at the second wavelength, wherein upon illumination at the second wavelength, all patterns generated by the first diffractive structure are diffracted under the horizon of the security device.
A security device comprising first and second diffractive structures contained within a surface relief structure, the surface relief structure being responsive to illumination at a first, visible wavelength, by a white light source, to generate a first, visible pattern, wherein all patterns generated by the second diffractive structure are not substantially visible at the first wavelength, and the surface relief structure being responsive to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading, all patterns generated by the first diffractive structure being substantially suppressed at the second wavelength, wherein upon illumination by the white light source, the pattern generated by the second diffractive structure is positioned angularly close to the direction of propagation of the illumination by the white light source and is thereby obscured from view.
A security device comprising first and second diffractive structures contained within a surface relief structure, the surface relief structure being responsive to illumination at a first, visible wavelength, by a white light source, to generate a first, visible pattern, wherein all patterns generated by the second diffractive structure are not substantially visible at the first wavelength, and the surface relief structure being responsive to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading, all patterns generated by the first diffractive structure being substantially suppressed at the second wavelength, wherein the second generated pattern is formed at a greater distance from the device than the first generated pattern upon illumination by the white light source.
Apparatus for authenticating a security device comprising first and second diffractive structures contained within a surface relief structure, the surface relief structure being responsive to illumination at a first, visible wavelength, by a white light source, to generate a first, visible pattern, wherein all patterns generated by the second diffractive structure are not substantially visible at the first wavelength, and the surface relief structure being responsive to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading, wherein all patterns generated by the first diffractive structure are substantially suppressed at the second wavelength, the authenticating apparatus comprising illumination means for illuminating the device at the second wavelength;
- detection means for detecting the resultant pattern generated by the second diffractive structure;
- and processing means for analyzing the detected pattern by comparison with a reference, wherein the illuminating means also includes means for illuminating the device with a white light source so that the pattern generated by the first diffractive structure may be viewed.
Dependencies are inferred from the claim text.