Cloaking device makes objects invisible – to infrared light

[Supreme_Warlord]

Scientists are a step closer to creating a Star Trek-style cloaking device after demonstrating a material that makes objects beneath it appear to vanish.

The material was used to hide a bump on a surface by interfering with the way light bounced off it, making it seem as though neither the cloak nor the bump was there.

The cloak was designed to make objects invisible to infrared light, but the work paves the way for more advanced materials capable of cloaking objects in visible wavelengths.

Some scientists believe cloaking materials could be used to hide unsightly buildings or high-security facilities, and even make vehicles seem to disappear from view.

Tolga Ergin and Nicolas Stenger at the Karlsruhe Institute of Technology in Germany used a technique called direct laser writing lithography to create a sheet of cloaking material from tiny plastic rods. The spacing of the rods, each of which measured one thousandth of a millimetre wide, alters a property of the material known as the refractive index, which changes the speed of light inside it.

The researchers placed a piece of the material over a dimple in a gold sheet and used infrared cameras to see what happened. When the cloak was in place, it altered the speed of light around the bump in such a way that the gold sheet appeared to be flat. The experiment was equivalent to hiding something under a carpet and having the carpet disappear too.

It is the first time researchers have demonstrated a cloak that works in three dimensions. Previous devices have hidden objects when looked at head-on, but did not work if viewed from the side. "We were surprised that the cloaking effect was still so good, Ergin told the US journal, Science.

Inside the material, the plastic rods are arranged like planks of wood piled up on each other. The high precision of the structure means it is possible to control the refractive index so it varies in just the right way to bend light around whatever object is hidden beneath it.

"The material has a higher refractive index on top of the bump, so light hitting that part is slowed down a little bit compared with light impinging on the rest of the surface," said Stenger. "That compensates for the shape of the bump, and in the end, it is exactly as if there was no bump."

Research into cloaking devices has attracted funding from military organisations, such as the US Defence Advanced Research Projects Agency, which backs high-risk science research for the Pentagon. In the near term, cloaking materials are expected to be used to hide aircraft from radar more effectively.

As yet, scientists have not been able to develop cloaking materials that make objects invisible to the eye, because visible light has shorter wavelengths that are more difficult to manipulate in the right way.

Beyond military applications, cloaking devices are drawing interest from telecommunications companies, who see them as a way to send information by light more efficiently. One idea is to use the new materials to build "superantennas" that can concentrate light and other electromagnetic waves to make laser-like beams.

"We are focusing on a new way to control light," said Stenger. "In the future of technology, light is going to have more and more importance."

Source

[Havok]

So it is just a matter of time then. That's a pretty cool and worrying discovery.

[phred]

So someday I may be able to have a real cloaking device, instead of just the social one I seem to have now?

Seriously though, that's pretty awesome.

[Fingolfin_Noldor]

Creating a wideband metamaterial is extraordinarily hard because the structures must be comparable to the wavelength of light. Red light is about 633nm, which implies that the structures must be close to this wavelength in terms of size. While it might be relatively easier to make the material narrowband to work on one wavelength, making the material wideband is a totally different matter.

In any case, a metamaterial really is akin to an RLC circuit for electric fields really. It's taking an old idea often used in RF electronics, and translating it for other EM frequencies.

[Havok]

Wow, I totally understood that. Just say' hey cool cloaking device!' like the rest of us will ya?

[JME2]

So it is just a matter of time then. That's a pretty cool and worrying discovery.

$5 says there's a Romulan disguised as one of the researchers...

[open_sketchbook]

Wouldn't this be hella awesome for a soldier to wear during night fights against enemies with low light vision systems? If it's a really dark night out, the standard procedure is an infrared spotlight that "illuminates" objects for the night vision systems. So if you had this going, wouldn't you remain more or less invisible even if the spotlight passed right over you? If this stuff ends of being practical, expect to see special forces types in it.