View Full Version : Invisibility-Cloak Materials Bend Light "Backward"

16-08-08, 04:23
This should be interesting, especially to Invisible Man & Harry Potter fans :D :wve:

Invisibility cloaks may be a bit closer to reality, researchers say, thanks to the development of two new materials that are the first to bend visible light the "wrong" way in three dimensions.

The so-called metamaterials are artificial composites designed to manipulate light in ways that natural materials can't—in these cases by refracting it backward.

If their cloaking capabilities are fully realized, metamaterials could make an object invisible by bending light waves so that they curve around the object and then reconnect, seemingly unaltered, on the other side—similar to the way water flows around a boulder.

"Of course cloaking captures everybody's attention, but these papers aren't [just] about cloaking," said Xiang Zhang, a professor at the University of California, Berkeley, and head of the research teams publishing related papers in two different journals this week.

"[The studies] are about the ability to engineer these material properties that never exist in nature. With that ability one can do many things, and cloaking is only one of them."

Such materials could also boost the power of microchips and antennas and allow the creation of "superlenses" that could image objects smaller than the wavelength of light, the study authors report.

Negative Refraction

One new metamaterial, described in Science, is a microscopic arrangement of silver wires—each about 20 times thinner than a human hair—embedded in aluminum oxide.

The other metamaterial, detailed online in Nature, is a layer cake of alternating nanoscale strips of silver and magnesium fluoride that were cut into a fishnet pattern.

Both materials exhibit negative refraction—bending visible light in a different direction than expected in nature.

A pencil sticking out a glass of water, for example, normally appears slightly bent at the point where it meets the water's surface but is still seen submerged. With negative refraction, the pencil would appear to stick back out of the water.

Previous metamaterials have been able to achieve a cloaking effect only in two dimensions in larger microwave wavelengths that are not visible to humans.

In addition to having 3-D negative refraction for a broader visible light spectrum, the new advances help overcome the sticky problem of energy loss.

Previous metamaterials actually absorbed most of the light, rather than bending it away, reducing the "invisible" properties. The new materials were designed to keep energy away from the most absorbent materials.

"It's like when you try to cross a river and keep your feet dry. You may jump across stones and cross without getting your feet wet," study leader Zhang said.

"That's exactly what we did. We tried to engineer these materials such that energy passing through is hopping through [other materials] and not the metal—because in the metal you have a big energy loss."

Scaling Up

David Schurig, a physicist and metamaterial expert at North Carolina State University in Raleigh, called the types of materials discussed by both papers "probably the most exciting metamaterials in existence today."

"Even in their current state, or maybe a few generations [later], they could have applications in optical communications or imaging," added Schurig, who was not involved with the research.

But, he noted, efforts to cloak anything above microscopic size are likely quite a ways off.

"You want to cloak things that are big, otherwise they are already essentially invisible, because they are [microscopic]," Schurig said.

"To cloak a person, you need metamaterial that's on that length scale, and that's much, much bigger than what [these papers] have demonstrated."

Link (http://news.nationalgeographic.com/news/bigphotos/89286476.html) to image of metamaterial prism :)

Source (http://news.nationalgeographic.com/news/2008/08/080812-invisibility-cloak.html)

16-08-08, 04:29
that's interesting...

16-08-08, 05:24
I saw this on msn a couple of days ago.- its absoloutely amazing. i cant wait to see the sorts of things we will be able to do in the future!!

17-08-08, 22:03
This should be interesting, especially to Invisible Man & Harry Potter fans :D :wve:


...and to all the pervs near the ladies' room. :p

17-08-08, 22:28
I saw this news being talked about on TV a couple of days ago!

This si gonna be so interesting! :)

17-08-08, 22:37
ive actually seen on discovery channel (or something like that) years ago where they were showcasing an invisibility cloaking device that was used on both people and a TANK. If i recall correctly, the technology that made it possible was fiber-optics.

edit: it was something similar to what was in this article here:

but was more effective than that actually... matter of fact.. after reading the article, it was nothing like that cause they showed the person moving and there was no video camera or projector. :vlol:

Nitro Typhoon
17-08-08, 23:05
Heard it on the radio a while ago. Sounds fascinating! :cln:

17-08-08, 23:11
OMG, i heard my dad telling me abou this a while ago. I thought he was pulling my leg. Thanks for verfying it Jo. :tmb:

18-08-08, 00:53
Metal Gear turns real! :tmb:

18-08-08, 01:04
Amazing! :tmb: They will never be mass marketed though. Imagine how high the crime rate would get. :p

18-08-08, 01:08
Intriguing, thanks for posting. :)

18-08-08, 01:16
I wonder what the military forces around the world will make of this technology. World War 3 will be a very scary time I'm sure with all this new technology.

18-08-08, 03:00
can anyone say "ninja":D

18-08-08, 03:18
^^ Ninja. ;)

This sounds very cool, and scary. :o

18-08-08, 07:47
wow....breakthrough after breakthrough....

18-08-08, 07:48
:yik:This is crazy!! Where can I purchase one??:p

18-08-08, 08:00
:vlol: ^exactly wat i was thinking....so taht i could "test" it out :mis:

18-08-08, 09:54
Would this be so effective against heat sensing equipment? I can see how it could be useful in a combat situation, but not so much so if more advanced technologies were being used by both combatants.

Nevertheless, it's awesome. I remember seeing this on Discovery Channel too a few years ago.

18-08-08, 10:01
^ If it won't work so great in open war, then at least they can use it on us civilians if we are deemed suspicious :tmb: :o

Metal Gear turns real! :tmb:

But of course.. :confused: was there ever any doubt it wouldn't?

: p

But this is definitely something worth keeping an eye on..

18-08-08, 10:06
I thought as much, still it would be good to see how this turns out.

As you said, definitely something to keep an eye on.

Wolf Angel
18-08-08, 10:30
omg I'd love to try that out! There are certain things I'd like to do with it :mis:

18-08-08, 10:54
Er, visual contact is not the only way to detect an object, and in warfare probably one of the least important anyway.

As you said, definitely something to keep an eye on.

Yes, I'll be on the lookout as well!

18-08-08, 11:30
Wow!:yik:Interesting! I do have to admit that invisibility cloaks can be very useful:D

18-08-08, 16:10
The question is, does it bend all light or just visible light?