Science

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

New cloaking device is no mira...
A new 'invisibility cloak' utilizes the same effect that causes mirages to appear (Image: Institute of Physics)
A new 'invisibility cloak' utilizes the same effect that causes mirages to appear (Image: Institute of Physics)
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A new 'invisibility cloak' utilizes the same effect that causes mirages to appear (Image: Institute of Physics)
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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.

Mirage effect helps researchers hide objects

11 comments
Mr Stiffy
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.
Gordon Torbet
It is a bit crap... not that I could do better.
Ianspeed
Damn, those Klingons are going to be pissed when they find out somebody stole their technology........
Dani73
One step towards a world of mischief.
Joe Santarromana
Cloak of invisibility for real!
James Forsyth
I could use it to hide in plain sight whilst giggling like Peter Griffin.
warren52nz
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?
Loving It All
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.
Mr Stiffy
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... http://www.youtube.com/watch?v=kAaNhStwhLs
Gregg Eshelman
Today, portable(?) mirages. Tomorrow, portable holes!