Multi-layer body with volume hologram

Abstract

Described is a method for producing a multi-layer body having a volume hologram with at least two different image information items, wherein a photosensitive layer (46) of the multi-layer body is brought into contact with the front side of a master (44) directly or by interposing a transparent optical medium (44s, 45), into which front side nested areas with different asymmetrical surface structures or kinoform structures are formed which embody the at least two different image information items. The photosensitive layer (46) and the master are exposed using a coherent light beam (47), by means of which a volume hologram is formed in the photosensitive layer (46). A master for producing the multi-layer body and a security element with said multi-layer body are further described.

Description

technical field [0001] The invention relates to a process for the production of multilayer entities with volume holograms, a body for volume hologram production, and a security element with multilayer entities. Background technique [0002] Holograms are used as security elements to protect security documents such as banknotes, ID cards or passports, security cards, etc. to achieve a high level of anti-counterfeiting. For mass-produced products, surface holograms are often used, which on the one hand do not produce the best image effects and on the other hand are easily reproduced by replicating the surface concave-convex shape. [0003] Volume holograms, also known as white-light holograms or reflection holograms, are based on the diffraction of light at Bragg planes called transparent layers whose refractive indices are locally different and which produce sharp image effects. They cannot be reproduced by surface relief. [0004] However, it should be noted that writing ...

AI Technical Summary

Problems solved by technology

[0008] Admittedly, such volume holograms are more secure than bulk holograms, but they are not as optically quality as surface holograms

Images