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New cloaking device is no mirage – but it's like one

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October 4, 2011

A new 'invisibility cloak' utilizes the same effect that causes mirages to appear (Image: ...

A new 'invisibility cloak' utilizes the same effect that causes mirages to appear (Image: Institute of Physics)

You have no doubt seen mirages on the distant surfaces of hot highways before, looking like pools of water shimmering on the asphalt. Such illusions are caused by hot air above the road, which refracts light waves coming down into it from the cooler air above - in other words, the supposed "water" is actually the sky, its image being bent toward you by the low-lying hot air. Well, scientists at the University of Texas at Dallas have put the same principle to work in the lab, and created an invisibility cloak that can be easily switched on and off.

The cloak itself is composed of a thin transparent layer of highly-aligned carbon nanotubes, which are known for their ability to conduct and disperse heat. This sheet is drawn taut on a mounting apparatus, and then placed in front of the object that needs to be hidden.

When viewed through the clear sheet, the object is completely visible. When an alternating electric current or a pulse of electromagnetic radiation is ran through the sheet, however, it becomes hot, and also spreads that heat to the air immediately around it. This causes a steep temperature gradient, which in turn causes light rays reflecting off the object to bend, instead of proceeding straight to the viewer's eye. As a result, the object seems to disappear.

As soon as the current is turned off, the effect ceases. The process is said to work particularly well underwater, as the video below illustrates.

A paper on the UT Dallas research was recently published in the journal Nanotechnology.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
11 Comments

Hmmm yes and mirages only work at a very shallow angle too...

I mean this is not crap - but it's limited to flat surfaces and shallow angles - and IR free detection.

Mr Stiffy
4th October, 2011 @ 05:36 pm PDT

It is a bit crap... not that I could do better.

Gordon Torbet
5th October, 2011 @ 04:29 am PDT

Damn, those Klingons are going to be pissed when they find out somebody stole their technology........

Ianspeed
5th October, 2011 @ 04:40 am PDT

One step towards a world of mischief.

Dani73
5th October, 2011 @ 09:26 am PDT

Cloak of invisibility for real!

Joe Santarromana
5th October, 2011 @ 09:56 am PDT

I could use it to hide in plain sight whilst giggling like Peter Griffin.

Jimmy Forcyth
5th October, 2011 @ 10:23 am PDT

Come on people. This is a project in progress, don't expect miracles all at once. Although I guess we all know what they have in mind for this technology once it's perfected!

Ah, where would we be without military funding?

warren52nz
5th October, 2011 @ 12:41 pm PDT

Interesting, but this begs for a more varied demonstration.

1. How does this work at different viewing angles?

2. In the current demo, the sheet mostly hid itself. Can it hide objects sitting behind the sheet?

3. What are the current size limitations for the effect?

These are all interesting questions which I believe could be answer right now, at least in the context of the prototype.

Loving It All
5th October, 2011 @ 02:25 pm PDT

It's not crap - as in bad, it's just the mirage effect of a hot boundry layer of air sticking to a surface ONLY works in a very narrow angle....

As a child in outback (stinking hot) Australia - these were NORMAL to see on the road in the middle of the day...... that shiny layer over the road, some distance away and as you get closer or the angle changes slightly - "huffff" (sound of ghost passing) - the mirage invisibilates.....

Gone...

Mr Stiffy
5th October, 2011 @ 04:54 pm PDT

Today, portable(?) mirages. Tomorrow, portable holes!

Gregg Eshelman
5th October, 2011 @ 08:51 pm PDT

I don't get it.

Suppose an invisibility cloak is a purchasable product- than what?

Who'd use it and for what purposes?

Chi Ken Sup
6th October, 2011 @ 05:33 am PDT
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