Duke University Creates Perfect, Centimeter-scale Invisibility Cloak

MrSeb writes "Scientists at Duke University have created the first invisibility cloak that perfectly hides centimeter-scale objects. While invisibility cloaks have been created before, they have all reflected some of the incident light, ruining the illusion. In this case, the incident light is perfectly channeled around the object, creating perfect invisibility. There are some caveats, of course. For now, the Duke invisibility cloak only works with microwave radiation — and perhaps more importantly, the cloak is unidirectional (it only provides invisibility from one very specific direction). The big news here, though, is that it is even possible to create an invisibility cloak of any description. It is now just a matter of time before visible-light, omnidirectional invisibility cloaks are created."

Comments

Hmmm

[ciderbrew]

I'll believe it when I see it.

Re:Hmmm

[vlm]

Unidirectional microwave-only cloak -> omnidirectional visible light cloak?
It's gonna take a little more than "a few years".

The biggest problem I see from having done lots of RF engineering in the lower microwave range (mostly FCC part 97, but some telco work, aside from the wifi stuff that "everyone" does) is specs always improve, but the basic layouts / schematics / ideas don't change very much.

Higher freqs? Sure. A heck of a lot of orders of magnitude? Um, maybe, over the course of a lifetime and billions of bucks. Unidirectional to omni? Um no.

You can make a "better" horn antenna. You can do crazy stuff to eat the sidelobes. You can make it lighter, or wider bandwidth, or better behavior when it multimodes. You can make it lower loss. But fundamentally, its still a microwave horn antenna. This fundamental issue is analogy to trying to make a unidirectional cloak.

This doesn't mean its useless. You know what would be funny? A anti-anything missile that is radar invisible from the pointy end. Who cares if you can see it from the back or side, its too late by then. To the best of my limited knowledge from playing Harpoon, etc, all American anti-anti-ship missiles are radar guided as are the ancient Phalanx miniguns.

One interesting RF observation is its a serious challenge to "really" do microwave RF work over a factor of 2 in freq. Can be done, but doesn't mean its easy or its more than cheating (multiple colocated systems... making a big pile simply isn't technologically interesting). The relevance is an X-band invisible car would probably not be invisible at K band. Or something invisible to red is probably going to be blue visible, unless you run multiple systems. Or something invisible to blue is probably not going to be invisible to IR targeting lasers.

Optimism.

[Anonymous Coward]

"It is now just a matter of time before visible-light, omnidirectional invisibility cloaks are created."

Wow. Just Wow. Just because we sent men to the moon, it does not mean that we'll be traveling to other galaxies soon.

Unless of course by "just a matter of time", they mean like a hundred thousand years.

Re:Optimism.

[CastrTroy]

I always like to refence this Hitchhiker's Guide quote

Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

There's a big different between going to the moon and even something like going to Mars. It only took Apollo 11 astronauts 3 days to get to the moon. Even the shortest trips to Mars have taken close to 300 days. And Voyageur 1 has been travelling for 25 years and is only now reaching the edge of the solar system.

While warp speed and worm holes could allow matter to travel vast distances over short periods of time, I don't know if actual things could travel though a worm hole or at warp seed without being torn apart.

Re:Optimism.

[slim]

Buzz Aldrin's proposed Mars Cycler would take about 5 months to shuttle "stuff" to and from Mars' orbit.

Haven't they learned from Star Trek?

[Tastecicles]

Surely it's gotta have a tailpipe...

Re:Cloaking first?

[captainpanic]

Looking at the capabilities of mobile phones today, I would suggest the tricorders arrived before the cloaking.

What I am saying is that it's one thing to develop an invisibility cloak. It's another thing altogether to avoid being tagged while wearing it.

perfect

[HPHatecraft]

now all we need to do is drag Stuart Little out of rehab (child stars... what more needs to be said?), and get him trained up over in Langley. With this invisible cloak, we can take rodint (rodent intelligence) to the next level.

Can someone look up cat populations in Iran at CIA's World Fact Book?

And with this...

[samazon]

My Harry Potter cosplay will be complete! Win!

Re:And with this...

[somersault]

"What do you mean I wasn't at your Halloween party? I was Invisibility Cloak Harry!"

Re:De facto legalization of murder.

[wbr1]

It has always been an internal moral compass that guides us. Few people do not commit murder or any other crime because of the fear of law enforcement.
The question becomes, does that moral compass derive from superstitious psuedo-belief in some omniscient power, government instilled fears, or a true sense of what is the path of the least harm to the fewest numbers of others?
If I really want to kill someone, or rob them, or rape them, I will find a way to do it, law and others be dammed. It simply becomes a matter of proper planning and (ahem) execution.
The invention of the knife did not 'legalize' murder, neither did the invention of the gun, or the fist for that matter. What legalizes it is our own mind and definition of moral. Regardless of the tools used.
Law enforcement, like much religion, is simply a fear mongering device used to direct the thoughtless masses.

Perfect?

[guttentag]

From the Oxford English Dictionary:

Perfect
adj. /'perfikt/
Having all the parts and qualities that are needed or wanted, an no flaws or weaknesses.

If there are caveats, it's not perfect. Don't slap false labels on things to make them sound more impressive. Call it what it is.

I don't think so...

[some1001]

The idea that we're "soon" to have invisibility cloaks that are both omni-directional *and* handle visible light is an unfounded one. True, maybe the underlying foundations are set well and the science is understood. But here's the issue: metamaterials ("invisibility cloaks" as a rule, fall into this category since they're properties are determined by the structure of the materials - not the material itself) have specific patterns in the structure. Microwave radiation has a wavelength between 1 mm and 1 m. Visible light has a wavelength of 390 to 750 nm. We are talking about four orders of magnitude.

The structure of the metamaterial needed to handle visible light is going to be out of our reach for quite some time until we can design a better way of handling structural details on the nanoscale and beyond (right now, the best methods are self assembled, and those methods usually aren't good for the massive complexity you'd desire).

Well, that's easy.

[Minwee]

I already perfected a centimeter scale invisibility cloak which works in visible light, but is unidirectional.

It involves using a digital camera, a printer, one square centimeter of paper and a bit of tape. Naturally, there are some limitations to where it can be used, but those are just details for the engineers to deal with.