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A method of forming a diffractive device

A technology of diffraction patterns and diffraction gratings, applied in the field of diffraction patterns

Inactive Publication Date: 2006-08-09
联邦科学和工业研究机构
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in these cases, the transparent cover film or OVD image is not personal to the individual, so there is a risk that by peeling off the transparent film and replacing the original photographic image with a substitute image, a replacement or falsified document could be produced to allow a different individual to use the ID file

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  • A method of forming a diffractive device
  • A method of forming a diffractive device
  • A method of forming a diffractive device

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Embodiment Construction

[0061] First, a preferred embodiment of the present invention is described with respect to the visual effect that may be produced when the MDI main pattern is combined with a sub-pattern in the form of a diffraction grating microstructure. Following this part of the description, some possible techniques for constructing a diffractive authentication pattern are described.

[0062] figure 1 is an illustrative example of a background OVD microstructure (or sub-pattern). exist figure 1 In , the pixel regions with different shades represent two different types of diffraction grating microstructures, which can be seen better in the enlarged section 10. For convenience, these shades are referred to as red (lighter shades) and blue (darker shades) pixel regions. Typical dimensions of a diffraction grating pixel area are 30 microns x 30 microns or 60 microns x 60 microns. For some applications, the pixel size may be smaller or larger than these figures, depending on the image resol...

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PUM

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Abstract

There is disclosed a method of forming a diffractive authentication device which generates an optically variable image which varies according to the angle of observation. The method comprises the steps of, providing a primary pattern which encodes a latent image, the primary pattern having a plurality of image elements, and providing a corresponding secondary pattern which will decode the primary pattern to allow the latent image to be observed when the primary and secondary patterns are in at least one registration, wherein the secondary pattern is provided by a diffraction grating microstructure having a plurality of each of at least two different types of diffraction elements. The primary pattern is provided such that predetermined image elements of the primary pattern render diffraction effects from predetermined diffraction elements of the diffraction grating microstructure optically ineffective at least at one observation angle when the authentication device is illuminated with a light source to thereby enable the latent image to be observed.

Description

[0001] This application claims priority from Australian Provisional Patent Application 2003903502, the disclosure of which is incorporated herein by reference. technical field [0002] The present invention relates to a diffraction pattern. [0003] When patterns made in accordance with embodiments of the present invention are illuminated with light sources, they generate one or more images that are visible around the pattern at a particular range of viewing angles. Patterns of embodiments of the present invention can be used in many different applications, and are particularly useful as ID documents (e.g., driver's licenses, credit cards, visas, passports, and other valuable documents that require secure Photocopying and computer scanning technology to counterfeit) anti-counterfeit security pattern. [0004] Embodiments of the present invention may also be used as low-cost security features for protecting banknotes, checks, credit cards, and other financial transaction docum...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B42D15/10B44F1/12B42F1/00
CPCB42F1/00
Inventor 罗伯特·阿瑟·李劳伦斯·戴维·麦卡锡格哈德·弗雷德里克·斯维格斯蒂莫西·约翰·戴维斯杰勒德·约瑟夫·威尔森
Owner 联邦科学和工业研究机构