Laser marked optically variable device
AssigneeCanadian Bank Note Company, Limited
InventorsThivaharan THURAILINGAM, Silviu CRISAN
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Abstract
A security device for security documents provides an angle-dependent Moire effect. A security device for a security document and method for making the security device are provided. At least two interlaced laser engraved images form an angle dependent parallax effect. First and second images are laser engraved at a substrate of the security document. To render the security device more difficult to copy, a colour changing effect or a nonreciprocal transmission effect may be achieved by adding a coloured (absorptive or emissive) layer between or within non-laser engravable layers situated between the laser engravable layers, and/or by adding a patterned phase diffraction grating situated between the laser engravable layers.
Claims18
A security device for a security document comprising at least two interlaced laser engraved images forming an angle dependent parallax effect wherein first and second images are laser engraved at a surface of a substrate of the security document, and the security device comprises a colour image on or within at least one non-laser-engravable layer situated between laser engravable layers.
A security device for a security document comprising at least two interlaced laser engraved images forming an angle dependent parallax effect wherein first and second images are laser engraved at a surface of a substrate of the security document, and the security device comprises a diffraction grating between laser engravable layers.
A method for making a security device for a security document comprising at least two interlaced laser engraved images forming an angle dependent parallax effect wherein first image and second images are laser engraved on a substrate of the security document, and the security device comprises a colour image on or within the at least one non-laser-engravable layer situated between laser engravable layers.
A method for making a security device for a security document comprising at least two interlaced laser engraved images forming an angle dependent parallax effect wherein first image and second images are laser engraved on a substrate of the security document, and the substrate comprises a diffraction grating between laser engravable layers.
Dependencies are inferred from the claim text.