De La Rue International Limited

Thomas De La Rue Limited

Drinkwater, Kenneth John

Kenneth John Drinkwater

Brian William Holmes

Ralph Kay

Paul Howland

Marianne Michelle Anton

Philip M Hudson

A diffuse reflector comprises a substrate () having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection hereinbefore defined.

Diffuse reflector and method

A diffuse reflector comprises a substrate () having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection hereinebefore defined.

An optically variable security device comprising a thin film reflection filter structure () which exhibits a first optically variable effect; and a relief structure () on or in the thin film reflection filter structure which exhibits a second optically variable effect.

Optically variable security device

A security device includes a holographic optically variable effect generating structure having at least two discrete section. The sections that generate in response to white light illumination an optically variable image having at least two defined graphical elements located at or near an image plane either on or adjacent to the plane of the device. In response to coherent illumination, the sections generate at least two discrete covert images, in the form of indicia, whose image planes are located at a distance away from the real place of the device. The covert images are reconstructed at different angles to a normal to a substrate supporting the device such that the covert images are spatially separated on their image plane, the covert images being non-visible under white light illumnination.

Security device

A security device comprises an optically variable effect generating structure ( ). An obscuring layer ( ) is located, in use, between the optically variable effect generating structure and a substrate ( ) to which the device is secured. A color layer ( ) is also included which exhibits one or more predetermined colors when viewed under certain viewing conditions from the side of the device remote from the obscuring layer. The obscuring layer ( ) is substantially opaque under the said certain viewing conditions.

A holographic security device comprising first and second holographic generating structures ( ) recorded in respective sets of substantially non-overlapping regions of a record medium is disclosed. The regions of one set are interleaved with regions of the other set, whereby both interleaved line structures are substantially non-visible to the unaided eye, whereby the holographic security device generates two or more holographic images (A,B) viewed from separate viewing directions around the device and normally seen by tilting the device. Each particular holographic image in a viewing direction is generated in whole or part by the holographic structure associated with one set of interleaved lines.

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Hampshire, United Kingdom

Kenneth John Drinkwater