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Abstract

A method of making a product containing a hologram which has at least two replay colours when viewed at a given angle, the method comprising the steps of: (i) recording holographic elements at each of at least two different angles in a master; and (ii) copying the master. The principle of the system is demonstrated by creating 2 surface relief objects, A and B on top of a mirror background. When a holographic recording medium is placed on top of this surface relief object and then illuminated with a coherent laser beam, interference patterns are recorded and developed within the polymer which describe the relief patterns (C-E). When the hologram is illuminated with white light and viewed normal to the hologram surface, the separation between the fringes relative to the viewing angle then becomes da and dc for surface relief objects A and B respectively (Figures C and E) and remains the same for the mirror (Figure D). This will then result in different frequencies of light or different colours being reflected at each specific viewing angle.

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First Claim