Security holograms
AssigneeBowater Holographic Research (Malta) Limited
InventorsPatrick Flynn, John David Wiltshire, John Henry Wiltshire
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Abstract
We describe methods of mass-producing full colour, 3D holograms, potentially incorporating a personalised image, which are particularly suitable for security purposes. Broadly speaking in embodiments a method generates, electronically, an interlaced image comprising a set of different views of a 3D object from different angles. This is projected onto a diffusing screen using coherent light and mapped from the screen into an angularly encoded object beam using a lenticular array. The different views in the angularly encoded object beam are then recorded simultaneously into holographic film using a reference beam.
Claims25
A method of recording a holographic image onto holographic recording film, said holographic image comprising a hologram of a three-dimensional (3D) object from a lenticular multi-channel image generation device, the method comprising:
- forming a holographic recording stack by:
- positioning said holographic recording film over said lenticular multichannel image generation device;
- generating said three-dimensional (3D) object using said lenticular multichannel image generation device;
- and
- recording said holographic image in said holographic recording film, forming a volume hologram by illuminating said stack through said holographic recording film with a laser light of at least one wavelength.
Apparatus for recording a security hologram in holographic recording film, said holographic image comprising a hologram of a three-dimensional (3D) object formed by a lenticular multi-channel holographic image, said apparatus including a stack comprising:
- said holographic recording film;
- a lenticular screen under said holographic recording film to generate a three-dimensional (3D) object;
- and
- an optical diffuser beneath said lenticular multichannel image generation device;
- and
- a reference laser beam arranged to illuminate said holographic recording film from above;
- and
- an object laser beam arranged to illuminate said optical diffuser beneath said lenticular multichannel image generation device;
- wherein an image under said lenticular screen comprises a multiplexed image containing stereographic depth or animation.
A method of recording a hologram encoding a view of one or more objects, the method comprising:
- generating, electronically, an interlaced image comprising an interlaced set of a plurality of different views of said one or more objects;
- projecting said interlaced image onto a screen using coherent light;
- mapping said different views of said one or more objects in said interlaced image into an angular encoding of said object beam using a lenticular array to generate an angularly encoded object beam in which different angles of said object beam correspond to different said views of said one or more objects;
- and
- recording different views of said one or more objects simultaneously into holographic film by interfering said angularly encoded object beam with a reference beam to record said hologram.
Apparatus for recording a hologram, the apparatus comprising:
- an image processing system to generate an interlaced image comprising an interlaced set of different views of one or more objects;
- a coherent light projection system to project a beam of coherent light bearing said interlaced image;
- a screen to convert said beam of coherent light to an intermediate image comprising said interlaced image;
- a lenticular array to encode said intermediate image into an angularly dispersed object beam in which different views within said interlaced image correspond to different angles within said angularly dispersed object beam;
- a coherent reference beam generation system to generate a coherent reference beam to interfere with said angularly dispersed object beam;
- and
- a holder to support a hologram recording medium in a region where said angularly dispersed object beam and said coherent reference beam interfere.
A master stack for mass production of a security hologram, the master stack comprising:
- a lenticular screen;
- a hologram master;
- and
- index matching material between said lenticular screen and said hologram master;
- wherein said index matching material comprises an adhesive locking said lenticular screen and said hologram master together.
Dependencies are inferred from the claim text.