Nav: Home

Holographic color printing for optical security

January 08, 2019

Researchers from the Singapore University of Technology and Design (SUTD) have invented a new type of anti-counterfeiting device that can be useful for counterfeit deterrence of important documents such as identity cards, passports and banknotes. Calling it "holographic colour prints", the research team led by Associate Professor Joel Yang demonstrated an optical device that appears as a regular colour print under white light, but projects up to three different images onto a distant screen when lit up with laser pointers. Unlike regular diffractive optical elements that have a frosted-glass appearance and projects only single images, these new holographic colour prints can be a stronger deterrent to counterfeiters while looking pretty at the same time. In addition, the prints consist of nano-3D-printed polymer structures and find particular use in optical document security.

Counterfeiting is a great menace to daily life, and the global anti-counterfeiting industry will reach more than US$ 357 billion by 2026 according to a report from Credence Research. Anti-counterfeiting products are important and essential for protecting products and documents. The most popular anti-counterfeiting products are based on holograms that can be found everywhere including on electronic device package boxes, medicine bottles, and surfaces of bank cards. However, these anti-counterfeiting hologram products only modulate the phase of light and can be easily copied.

The SUTD research team developed a new type of anti-counterfeiting device, i.e. holographic colour printing, which modulates both the phase and amplitude of light. Holographic colour printing displays a coloured image under ambient white light by tuning the amplitude of light, while projecting up to three different holograms under red, green, or blue laser illumination. This feat was achieved by fabricating a new type of nanostructured pixel strategically arranged on a plane. Each pixel acts as a speed bump (phase control) and road blocks (amplitude control) for light. The dual-function of holographic colour printing increases security and deters counterfeiting.

Associate Professor Joel Yang shared that the device's colour pixels are created by overlaying structural coloured filters onto phase plates. Nanostructured posts of different heights are employed as structural coloured filters to modulate the amplitude of light. The team developed a computer algorithm that takes multiple images as its input, and generates an output file that determines the positions of different phase and coloured filter elements. The holoscopic print was then sculpted with the aid of a nanoscale 3D printer. The team used Luigi Russolo's art painting Perfume (1910) as a colour print that is viewable under ambient white light. Different thicknesses of polymerised cuboid are used to modulate the phase plates and form three multiplexed holograms, projected as a red thumbprint, a green key, and blue lettering that reads "SECURITY". All of these images were embedded within a single print.

"The relationship of holograms in combating counterfeiting is analogous to antibiotics against infections. Every so often, new technology is needed to deter counterfeiters as the old fashioned holograms become easier to copy," said Joel Yang

He further added, "For the first time, multiple holograms that are color selective are 'woven' into a colourful image using advanced nanofabrication techniques. We are hopeful that these new holographic colour prints are user friendly but counterfeiter unfriendly: They are readily verified but challenging to copy, and can provide enhanced security in anti-counterfeiting applications."
-end-
This study was published in Nature Communications, titled "Holographic Colour Prints for Enhanced Optical Security by Combined Phase and Amplitude Control" on 3 January 2019.

Singapore University of Technology and Design

Related Holograms Articles:

Seeing the forest through the trees with a new LiDAR system
Researchers from the Naval Research Laboratory use gated digital holography methods to develop foliage penetrating LiDAR that can survey obscured ground.
New femto-camera with quadrillion fractions of a second resolution
Researchers from ITMO University have built a setup for recording holograms of tiny objects like living cells with a femtosecond speed.
World's thinnest hologram paves path to new 3-D world
Researchers pave way towards integration of 3-D holography into electronics like smart phones, computers and TVs, with development of nano-hologram 1,000 times thinner than a human hair.
Stretchable hologram can switch between multiple images (video)
The possibility of sending and receiving holographic messages has long tantalized sci-fi fans.
Holography with the Wi-fi-router
Scientists at the Technical University of Munich (TUM) have developed a holographic imaging process that depicts the radiation of a Wi-Fi transmitter to generate three-dimensional images of the surrounding environment.
Technique makes more efficient, independent holograms
Recently, a team of researchers encoded multiple holographic images in a metasurface that can be unlocked separately with differently polarized light.
Study reveals substantial evidence of holographic universe
A UK, Canadian and Italian study has provided what researchers believe is the first observational evidence that our universe could be a vast and complex hologram.
A new approach to 3-D holographic displays greatly improves the image quality
A research team led by Professor YongKeun Park of the Physics Department at the Korea Advanced Institute of Science and Technology (KAIST) has come up with a solution and developed a 3-D holographic display that performs more than 2,600 times better than existing 3-D holographic displays.
Sci-fi holograms a step closer with ANU invention
Physicists from The Australian National University have invented a tiny device that creates the highest quality holographic images ever achieved, opening the door to imaging technologies seen in science fiction movies such as 'Star Wars.'
Quasi noise-free digital holography
Noise originating from the coherent nature of laser light is the scourge of digital holography, always causing holographic images to be of lower quality than conventional photographs.

Related Holograms Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".