metamaterial masking moves toward practical application

24 02 2011

Via Rachel Courtland, New Scientist. Issue 2800

NOW you see it, now it looks like something else. Radar images might never be the same again, thanks to an illusion device that can change an object’s appearance. The technology could ultimately be used to hide military aircraft.

The device is part of a growing family of metamaterials – structures designed to steer light along curved paths. They have already been used to make objects appear invisible and to disguise a gap between two objects.

Wei Xiang Jiang and Tie Jun Cui’s team at Southeast University in Nanjing, China, have created a structure that changes the way radio waves interact with a copper cylinder so that it appears to be composed of another material altogether.

Copper conducts electricity well and reflects incoming radio waves, giving it a bright radar signature. To alter this behaviour, the team built a device made of 11 concentric rings of circuit boards etched with small metal-lined channels that prevent electromagnetic waves reflecting away. Instead, they guide the waves in a direction that the researchers choose specifically to make the hidden object appear to have different electrical properties.

Placed around a copper cylinder, the arrangement created the illusion that the cylinder was made of a dielectric, a class of materials including porcelain and glass that do not conduct electricity and are more transparent to radio waves.

"Electromagnetic cloak"

A similar waveguide that rendered small objects invisible was tested in 2009.

The illusion only worked when the cylinder was viewed from the side; what’s more, the imaginary object it generated was the same size as the original. Future designs would have to account for all three dimensions, and might produce an illusion quite different from the object they disguise.

“In principle, this technology could be used to make an illusion of an arbitrary shape and size,” says Cui, whose team created an electromagnetic “black hole” for light in 2009. Similar illusion devices could eventually be used for stealth technology: for example, to “convert the radar image of an aircraft into a flying bird”, Cui says.

The work, which will be published in Physical Review E, is still at an early stage, however. At 45 millimetres, the team’s illusion device is three times as wide as the cylinder it disguised. “Their device is still fairly bulky relative to the original object, so further work needs to be done before a real device can be deployed,” says John Pendry of Imperial College London.

Although invisibility devices were invented first, the illusion technology might win the race to be put to practical use. “It is easier to falsify something than to hide it,” Pendry says.

The team next plans to explore ways to design devices with more complex shapes.





metamaterials, laser resin and invisibility cloaks

6 08 2010

Metamaterials can bend light around objects to render them near-invisible, begins a recent report in New Scientist. But it is an imperfect, lossy process, meaning some light is absorbed on its way through the metamaterial, and therefore the object remains semi-visible.

Now a team of scientists at Purdue University in West Lafayette, Indiana have invented a light amplifying resin ‘sandwich filling’ which, when stimulated by a laser, creates gain in the electro-optical signal, restoring the ‘lost’ light. The “negative-index metamaterial” means that an object can now conceivably be made  invisible to specific wavelengths of light.

Previous metamaterials, utilising nanoholes in a carbon matrix, IIRC, were able to mask objects in the microwave end of  the electromagnetic spectrum, but visible light has until now been elusive.

A wearable device is still light years away (pardon the pun!), but military installations, ships and even armoured vehicles are most definitely foreseeable near-term applications for the invisibility treatment.

Watch this space. Not that you’ll see anything ;-)





coast clear for invisibility cloak?

21 08 2009

An illustration of a person wearing an invisibility cloak

For now, the invisibility cloak remains a thing of science fiction

From BBC News, Thursday 20th August 2009

A physicist has said he hopes to make major advances in the field of invisibility in the next two years.

Professor Ulf Leonhardt at St Andrews University is working on a blueprint for a cloaking device that could also be used to shield coast lines.

The researcher, who cites the Invisible Woman and Harry Potter as inspiration, has been working on the concept of invisibility since 2006.

The project will focus on a connection between light and curved space.

Prof Leonhardt, who describes his invisibility work as “geometry, light and a wee bit of magic”, hopes to manipulate modern metamaterials – or “designer atoms” to create an invisibility device using the laws of refraction.

He believes that in bending light, transparent materials like glass or water appear to distort the geometry of space, which is the cause of many optical illusions, including invisibility.

‘Extreme ideas’

Prof Leonhardt said: “The idea of invisibility has fascinated people for millennia, inspiring many myths, novels and films.

“In 2006, I began my involvement in turning invisibility from fiction into science, and, over the next two years, I plan to develop ideas that may turn invisibility from frontier science into applicable technology.”

Although the professor admitted it was difficult to predict possible applications, he suggested invisibility research could be used to improve visibility, leading to the development of the perfect retroreflectors (cats eyes), better microscopes and improved lenses.

He added: “I will most certainly find easier ways of cloaking, but it remains to be seen how practical they are.

“The important thing is to understand the foundations and come up with something new or take an existing idea to extremes; using technology and ideas to make things happen – technology we cannot imagine would ever exist.”

The project is being funded by the Royal Society’s Theo Murphy Blue Skies Award.





camo for cameron

1 08 2009

A rumour came to my attention today. The rumour has it that James Cameron, director of classics such as The Terminator and Terminator 2, Aliens and the Abyss, as well as True Lies and Titanic, has been wearing my company’s PenCott digital fractal camouflage on the set of his latest film project: Avatar. The rumour appears to have grown from a photograph in the latest edition of Empire magazine, showing Cameron demonstrating how to man the door-gun of a troop transporter, wearing a pair of trousers in an unusual digital camouflage.

35565

NOT gunning for PenCott. Copyright: Empire magazine

Much as I would love one of my movie idols to be wearing PenCott in association with a futuristic film, sadly he is not. His lower half seems to be clad in a commercial camo (note the bigger, more obvious pixels and the black areas). Should James Cameron like some genuine Hyde Definition trousers in our cutting-edge PenCott pattern, he is welcome to get in touch and I will happily furnish him with a pair or two, plus shirts and hats to boot. Someone pass the message to him, eh?





transformed: Megan Fox in futuristic camo

20 06 2009

Megan Fox was at the premiere of this summer’s expected big box-office blockbuster, Transformers 2, in Berlin recently. Here’s how she could have looked if that dress was made with PenCott camouflage material…





scientists claim closer to success with invisibility shield

20 08 2008

Looks like a great story, doesn`t it? From scence fiction to science fact. But the full scoop from Defence Tech is another example of “nothing to see here, move along please”.

There is a pie in the sky - can you see it?

There is a pie in the sky - can you see it?

The article states that

according to Dr. Richard Hammond, a theoretical physicist with the Optical Physics and Imaging Science department of the Army Research Office, engineers are closer than they’ve ever been to developing a material that can bend light around an object rendering it invisible to certain wavelengths — light being one of them.

It claims

there are some significant obstacles to making a usable “invisibility cloak,” however.

But get this:

“in early applications we could shield an object from radar,” Hammond added.

So apparently some boffins have reinvented RAM (radar absorbent material) as used on stealth planes and ships. Whoopee-frickin`-doo!

Hey, you know what? I`ve come up with this great concept: It`s basically a disc with a hole in the middle. I think if you put some sort of rod through the hole you could rotate the disc around it, and if you had a disc on the other end, you would be able to hold the rod off the ground with them. I call it a centrally rotating axial perambulation device. I`m sure there must be thousands of practical applications for it. Perhaps the guys at the Army Research Office could find a use for it. If they haven`t already invented it, that is.








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