Device with anti-counterfeiting diffractive structure
AssigneeOptaglio Limited
InventorJohn Drinkwater
Life of this patent
Estimating the term…
Abstract
An optical device for security and anti-counterfeit applications comprises a diffractive structure comprising a discrete region that in response to white light illumination generates an image by a process of diffraction in close angular proximity to the specular reflection and which is thus substantially non-visible to an observer, and which under coherent illumination generates a laser projection covert image which forms an image in an image plane located away from the physical plane of the device and which is angularly co-located in close proximity to the direction and position of the specular reflection.
Claims27
An optical device comprising at least one discrete region comprising a diffractive structure wherein the diffractive structure is arranged to replay in response to white light illumination exhibiting specular reflection a first image in close angular proximity to the specular reflection of the white light such that the first image is non-visible to an observer, and wherein the diffractive structure is arranged to replay in response to coherent light illumination exhibiting specular reflection a second covert image visible to an observer when imaged on a separate image plane located away from the physical plane of the optical device and replaying in close angular proximity to the specular reflection of the coherent light.
Dependencies are inferred from the claim text.