De La Rue International Limited

Maria King

Brian William Holmes

Frederic Fournier

Fred Fournier

An optical device is provided that exhibits a variable optical effect upon illumination. The optical device has a diffractive structure comprising: a portion of a first kinoform diffractive structure that encodes a first image, arranged to form a first diffractive region () of the diffractive structure; and a portion of a second kinoform diffractive structure that encodes a second image, arranged to form a second diffractive region () of the diffractive structure; wherein the first diffractive region and the second diffractive region are laterally separate; and each of the first diffractive region and the second diffractive region are discernible by the naked human eye. Methods of manufacture of such optical devices are also disclosed.

Optical devices and methods of manufacture thereof

A security device includes a diffractive structure, including grating elements and having a first area, the grating elements within a region have a constant pitch or spacing; the first area regions pitches or spacings increase from one region to the next between a first region having a grating element pitch or spacing of less than or equal to 0.6 microns and an end region having a grating element pitch or spacing of greater than or equal to 5 microns; upon illumination and viewing along a first viewing direction substantially orthogonal to the first axis, the device exhibits a first optical effect in that at least one region exhibits a diffractive colour; each region has at least first and second sub-regions having different grating element orientations within the plane of the device such that the first optical effect is exhibited at more than one angle of tilt about the second axis.

Security device and method of manufacture thereof

A security element including: a first layer having a first surface; an array of image regions across the first surface arranged along at least a second direction, each region including at least a first image sub-region having an average inclination defining an angle, relative to a plane of the security element, about an image region axis extending along a first direction; a diffractive optically variable effect generating structure provided in or on the first surface across the first image sub-regions, the structure including diffractive elements that extend along a direction within 45&#xb0; of the first direction, wherein the structure is provided across the first image sub-regions and spatially arranged and/or modulated across the first image sub-regions in accordance with a first image so the first image is displayed by the first image sub-regions in combination at least at a first viewing angle. Also, a method of manufacturing the security element.

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Basingstoke, United Kingdom

Maria King