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article imageFirst stretchable holographic display revealed

By Tim Sandle     Aug 10, 2017 in Technology
By using gold nanorods embedded into a contact lens material, technologists have succeeded in creating a new kind of holographic display. The display is based on a special film which is stretchable.
Holographic displays are likely to have a big take-up by businesses, advertisers and by the entertainments industry. Imagine, for instance, a novel tabletop display system that allows multiple viewers to simultaneously view a hologram showing a full 3-D image as they walk around the tabletop, giving complete 360-degree access? This could be used for video conferencing, showcasing new products like cars or for broadcasting movies. This type of technology is developing at a fairly rapid pace. Such developments are featured in a recent Digital Journal article “Holography will be the next big thing in electronics.”
With the new development, based on gold nanorods, the display is possible due to advances in materials sciences, especially with metamaterials and metasurfaces that possess optical properties. These materials work through repeating elements which are able to interact with electromagnetic waves. These waves reflect, bend, and distort light in new and interesting ways and form holograms. A hologram is a physical structure that diffracts light into an image. The word ‘hologram’ refers to both the encoded material and the resulting image.
What the researchers behind the development have done is to design materials with all the features of negative refractive index and super-resolution lenses. This is down to metasurfaces acting as computer-generated holograms, which is outlined in new research conducted by Professor Stephanie Malek and colleagues, who work at the University of Pennsylvania in Philadelphia. The research group, as Technology Review reports, has succeeded in printing a hologram onto a metasurface; the long-term aim is to develop a new type of display that switches the information it displays as it stretches. Stretching is key since pulling the substrate enlarges the hologram image and changes the location of the image plane.
Watch a hologram change shape:
An electromagnetic metasurface is an artificial sheet material that possesses sub-wavelength thickness and electromagnetic properties on demand. The flexible polymer film surfaces are formed from an array of tiny conducting gold nanorods. These rods influence the way light reflects off them. By spatially varying the orientation of the rods, differing patterns can be formed in the reflected light, with the optimal patterns needed for create a hologram determined by a computer. A computer is needed to calculate how much a holographic image expands as the material generating it stretches, and how far the image plane moves away from its original position.
Professor Malek created his surfaced by covering a silicon wafer with plastic (polydimethylsiloxane) and then using photolithographic techniques to create the desired pattern. The remaining plastic was next coated with gold and then the film is poured on to the surface to create a layer that covers the gold nanorods. The end product is a thin layer of material containing gold nanorods in a pattern that creates a hologram. This prototype technology could one day be used for a new type of display.
A white paper has been produced, describing the technology in more detail. It is titled “Strain Multiplexed Metasurface Holograms on a Stretchable Substrate.”
If you found this article on ultrathin holograms of interest, please read our look new ultra-thin hologram which could one day be integrated into tablets and smartphones: “World’s thinnest hologram developed.”
More about Hologram, holography, display screen, Visual, Nanotechnology