Holographic security element and method of forming thereof

Patent metadata

Field	Value
Publication number	US-2020331283-A1
Application number	US-201816754317-A
Country	US
Kind code	A1
Filing date	Nov 2, 2018
Priority date	Nov 3, 2017
Publication date	Oct 22, 2020
Grant date	—

Abstract

There is provided a holographic security element including a substrate; and an array of nano-reflectors configured to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the substrate when irradiated with a predetermined light source. In particular, the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern. There is also provided a method of forming the holographic security element, and an article having one or more holographic security elements incorporated therein.

First claim

What is claimed is:

1 . A holographic security element comprising:
a substrate; and an array of nano-reflectors configured to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the substrate when irradiated with a predetermined light source, wherein the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern.

2 . The holographic security element according to claim 1 , wherein the size of the pattern is at most of micron scale and the size of the holographic image is at least of centimeter scale.

3 . The holographic security element according to claim 2 , wherein the size of the pattern has a largest lateral dimension that is smaller than about 1,000 micrometers, and the size of the holographic image has a smallest lateral dimension that is larger than about 1 centimeter.

4 . The holographic security element according to claim 2 , wherein the size of the holographic image is at least 50 times larger than the size of the pattern.

5 . The holographic security element according to claim 1 , wherein the array of nano-reflectors is configured to directly generate the holographic image at the predetermined distance.

6 . The holographic security element according to claim 1 , wherein spatial locations of the array of nano-reflectors on the substrate are configured to form the pattern such that interference of the reflected light from the array of nano-reflectors when irradiated with the predetermined light source generates the holographic image having substantially said size at the predetermined distance.

7 . The holographic security element according to claim 1 , wherein the predetermined light source is a laser light source.

8 . The holographic security element according to claim 1 , wherein each of the array of nano-reflectors is a nano-mirror.

9 . A method of forming a holographic security element, the method comprising:
providing a substrate; and configuring an array of nano-reflectors to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the holographic security element when irradiated with a predetermined light source, wherein the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern.

10 . The method according to claim 9 , wherein the size of the pattern is at most of micron scale and the size of the holographic image is at least of centimeter scale.

11 . The method according to claim 10 , wherein the size of the pattern has a largest lateral dimension that is smaller than about 1,000 micrometers, and the size of the holographic image has a smallest lateral dimension that is larger than about 1 centimeter.

12 . The method according to claim 10 , wherein the size of the holographic image is at least 50 times larger than the size of the pattern.

13 . The method according to claim 9 , wherein the array of nano-reflectors is configured to directly generate the holographic image at the predetermined distance.

14 . The method according to claim 9 , wherein said configuring the array of nano-reflectors comprises configuring spatial locations of the nano-reflectors in the array of nano-reflectors on the substrate to form the pattern such that interference of the reflected light from the array of nano-reflectors when irradiated with the predetermined light source generates the holographic image having substantially said size at the predetermined distance.

15 . The method according to claim 14 , wherein the spatial locations of the nano-reflectors are configured based on a genetic algorithm, and
wherein based on the genetic algorithm, said configuring the spatial locations of the nano-reflectors comprises: mutating a current chromosome array comprising nano-reflector location information to produce a mutated chromosome array; computing an interference of reflected light at the predetermined distance based on the nano-reflector location information of the mutated chromosome array; and determining whether to accept the mutated chromosome array based on whether the computed interference associated with the mutated chromosome array is closer to a target interference of reflected light at the predetermined distance for generating the holographic image than a computed interference of reflected light at the predetermined distance associated with the current chromosome array.

16 . The method according to claim 15 , wherein the current chromosome array comprises a plurality of elements, each element respectively corresponding to a possible nano-reflector location on the substrate and indicates a presence or an absence of a nano-reflector at the possible nano-reflector location, and said configuring the spatial locations of the nano-reflectors comprises performing iteratively, for each element of multiple elements or each subset of multiple subsets of elements of the plurality of elements, said mutating a current chromosome array, said computing an interference and said determining whether to accept the mutated chromosome array.

17 . The method according to claim 16 , wherein said configuring the spatial locations of the nano-reflectors further comprises generating an initial chromosome array comprising the plurality of elements, each element being randomly set to indicate either a presence or an absence of a nano-reflector at the corresponding possible nano-reflector location.

18 . The method according to claim 9 , wherein the predetermined light source is a laser light source.

19 . The method according to claim 9 , wherein each of the array of nano-reflectors is a nano-mirror.

20 . An article having one or more holographic security elements incorporated therein, each of the one or more holographic security element comprises:
a substrate; and an array of nano-reflectors configured to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the holographic security element when irradiated with a predetermined light source, wherein the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern.

Assignees

• Agency Science Tech & Res

Inventors

• Huang Kun
• Teng Jinghua
• Goh Xiao Ming
• Tan Junhao Shawn

Classifications

• B42D25/373

  Metallic materials · CPC title

• G06K19/06178

  the marking having a feature size being smaller than can be seen by the unaided human eye · CPC title

• G06K19/06037

  multi-dimensional coding · CPC title

• G06K19/06084

  the marking being based on nanoparticles or microbeads · CPC title

• G03H1/0011

  for security or authentication (holograms on information-bearing cards B42D25/328; testing papers with holograms G07D7/0032) · CPC title