Opsec Security Group, Inc.

University of East Anglia

Paul Dunn

Robert Edward Renton

Dean Hill

Andrew K Rowe

Donald William Tomkins

Andrew Neil Cammidge

Andrew Rowe

The invention generally relates to optically variable devices, methods of preparation and applications or uses therefor. In particular, the invention includes trigger molecules employed as a dopant for a liquid crystal material. The liquid crystal material contains helical elements having a natural twist. The dopant is effective to change the natural twist of the helical elements when the dopant is addressed with incident light. Suitable dopants are selected from binaphthalene and derivatives thereof.

Security device using liquid crystals

A security device includes an optically variable device (OVD) having diffraction-based micro-optics including at least one moir&#xe9; magnified visual representation of a micro-object. A diffractive structure provides micro-objects with unique optical effects when the OVD is viewed through the micro-object structure from a predetermined relative observation point. In addition to magnifying the micro-objects, the diffractive structure can impart optical effects such as change in observed color, enhanced contrast, animation of the observed visual representation, and change in size or shape of the observed visual representation. The micro-objects and the diffractive structure can be disposed on the same or different portions of a substrate. A method of making OVDs, and an article employing such OVDs are also disclosed.

Optically variable device with diffraction-based micro-optics, method of creating the same, and article employing the same

An optically variable device ('OVD') with an integral image system that includes a focusing element and an array of micro-objects which, when viewed through the focusing element, changes in appearance depending on the relative location from which the OVD is observed. A security device including the OVD and methods for creating the OVD are also disclosed.

Optically variable devices, security device and article employing same, and associated method of creating same

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Paul Dunn