Engineers Devise Invisibility Shield

GerritHoll points out an article in Nature according to which "researchers at the University of Pennsylvania 'say that a "plasmonic cover" could render objects "nearly invisible to an observer.' Earlier attempts at invisibility worked by colouring a screen to match its background, like a chameleon. The described technique is new, because it works by the concept of reducing light scattering. It is not a 'magic cloak,' however, because it will not work for the full range of visible light and needs to be adjusted precisely for the shape of the object. However, the concept could find an application in stealth technology."

Restrictions far too great

[jgardn]

The object being hidden has to be less than the about the wavelength of the light. So, unless you are nanometers in size, you won't be hidden from visible light.

And it only works on one frequency. Meaning, unless you are nanometers in size, and you are in a room with only red light, you won't be hidden.

This isn't that great. I wouldn't read too much into it.

Re:Restrictions far too great

[digitallife]

Whatever. *I* think its neat. When the telegraph was invented, no one could imagine a telephone... let alone an internet.

What about other wavelengths?

[Crash24]

What if this concept works for other EM waves, like radar, for instance? I don't remember the precise wavelength of most radar waves, but they are rather long (I'm thinking meters). Could an object smaller than the wavelength of a certain radar be stealthed by this "invisibility" shield?

Re:Indeed, it's pretty far from advertised...

[poopdeville]

Planes are relatively small, and the sky is big. One really needs microwaves to detect a plane flying at high speed. Notice that I said radar invisible. It's well known that the stealth aircraft skins are very bumpy, with smaller bumps on the larger, to increase unidirectional scattering at various frequencies. Moreover, they use an anti-reflective coating. I suspect that this, if tuned to microwaves and built a few layers deep, would be used (if it isn't already) by the military, as it would effectively increase the bumpiness to microscopic levels.

Re:"precise wavelength of most radar waves"

[Crash24]

I did some research [aewa.org], and I found that VHF and UHF bands (about 6 to .3 meters wavelength) are used for long range serveiliance. So hiding a small object from long range radar may be possible...but other than that it's a long shot.

Re:Invisibility cloaking

[Dunbal]

According to the site it's because the hypothetical surgeon can't see what he's doing because his hand is in the way. The only problem is I'd need to stick a camera in front of my hand to get an image, and this would sort of interfere with any instrument I was using. Oh well, it's a good thing (most) surgery is not as complicated as all that...

Re:Invisibility cloaking

[Chris Kamel]

Perhaps even more of a drawback, he points out, is the fact that a particular shield only works for one specific wavelength of light.
An object might be made invisible in red light, say, but not in multiwavelength daylight.
So this should mean that a cloak made for red light invisibility should change an object's color in multi wavelength daylight as it absorbs red and leaves the rest?

Re:Indeed, it's pretty far from advertised...

[X0563511]

This wouldn't work. The radar would pass through the molecules, only to reflect off of the aircraft skin, and pass back though the molecules.

Now, if it could be set up so that the radar would pass through once, and bounce around between the skin and the coating before finding the right angle to escape, it would probably make the radar bounce off the plane at all kinds of weird angles (making the radar useless).

The problem I'm wondering about is: What happens if the radar can't find a way out? Will it keep bouncing around, loosing energy all the while, heating up both the skin and the coating (this may become an issue)? Or would the time and energy it spent bouncing around untill it escaped be so trivial so as to not matter?

Re:front projection

[noselasd]

Oh pffft, if it was used in a film trick, what idiotic news
is it when someone makes it real ?

Re:front projection

[Metryq]

There is also a scene where Bond must sneak past some guards and get back in his car...he "hides" behind the car for coverage.

This article says nothing

[a_nonamiss]

"Blah blah blah Plasmonic shield Light scatter Blah blah blah invisibility camoflauge blah blah blah stealth technology Romulans (ha ha ha) blah blah Oh, and by the way, it can't hide anything larger that a few subatomic particles"

That's hardly groudbreaking. I'm sure the research is fascinating in the small circles that it affects, but not in the real world. They're not even pretending it will ever be able to make anything invisible. I'm sure that the real scientists who invented this never touted it as a cloaking shield, just the sensationalist news outlets that got ahold of the story.

Re:Everybody knows

[Kiryat Malachi]

That's cool. I wasn't doubting the veracity of the story; but you have to admit, 'plasmons' sounds like ones of those words made up for bullshit Trek science.

This just in....

[feloneous cat]

And crucially, the effect only works when the wavelength of the light being scattered is roughly the same size as the object. So shielding from visible light would be possible only for microscopic objects...

Which are frikkin' microscopic and therefore don't need to be hidden?

Or is it just me that can't see microscopic objects?

Re:front projection

[logophage]

The alleged surgical and pilotting applications sound equally silly. It is an infinite regression of "if we can fit a camera in front of the surgeon's hands, we can project an image behind them to make a really cool effect that they are invisible!

This isn't exactly true. You can use photogrammatric techniques to calculate what the image would like from a given angle if you have 2 or more cameras seeing the object at other (non-oblique) angles.