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Cloaking

The acoustic cloak was constructed from several sheets of plastic plates dotted with repea...

Metamaterials are already being used to create invisibility cloaks and "temporal cloaks," but now engineers from Duke University have turned metamaterials to the task of creating a 3D acoustic cloak. In the same way that invisibility cloaks use metamaterials to reroute light around an object, the acoustic cloaking device interacts with sound waves to make it appear as if the device and anything hidden beneath it isn't there.  Read More

View of the equipment supporting an active invisibility cloak and the cloak itself (Photo:...

Sometimes everything can seem to happen at once. The new game in town is active invisibility cloaks (AIC), which use electronics and antennas to generate a cloaking field to hide an object. Two types of active cloaks have just been revealed (excuse the pun). While being impressive feats of technology, such cloaks could easily be defeated in practice.  Read More

While one would hope to make an invisibility cloak that performs like the central image, i...

It's often a case of swings and roundabouts. If you save money by buying a house out of town, you spend more time and money commuting. If you really measure the momentum of an electron, you have no idea where the little guy is located. And now, according to a new analysis by a pair of University of Texas electrical engineers, the better an object is hidden by an invisibility cloak at a given wavelength of light, the easier it is to see at other wavelengths. Swings and roundabouts.  Read More

A Stanford breakthrough in optical metamaterials could enable fabrication of a wide-spectr...

To make a Harry Potter-style invisibility cloak requires that the materials from which it is made have a negative refractive index over all optical wavelengths, from red to violet. However, the artificially-structured optical materials from which cloaks are made thus far have been restricted to a very narrow range of optical wavelengths, limiting their ability to cloak over a range of colors. That obstacle to progress ends now, as a group of Stanford optical engineers at Stanford has succeeded in designing a broadband metamaterial that exhibits a negative refractive index over nearly the entire rainbow.  Read More

Yaroslav Urzhumov with the 3D-printed invisibility cloak developed at Duke University

Invisibility cloaks have been around in various forms since 2006, when the first cloak based on optical metamaterials was demonstrated. The design of cloaking devices has come a long way in the past seven years, as illustrated by a simple, yet highly effective, radar cloak developed by Duke University Professor Yaroslav Urzhumov, that can be made using a hobby-level 3D printer.  Read More

Brazilian oil platform P-51 (Image: Agência Brasil/Wikipedia)

Recent years have seen much progress in the development of invisibility cloaks which bend light around an object so it can't be seen, but can the same principles be applied to ocean waves that are strong enough to smash steel and concrete? That's the aim of Reza Alam's underwater “invisibility cloak.” The assistant professor of mechanical engineering at the University of California, Berkeley, recently outlined how to use variations of density in ocean water to cloak floating objects from dangerous surface waves.  Read More

Mathematicians are proposing a cloaking system, which could allow buildings to be rendered...

While “cloaking” technology may have once been limited exclusively to the realm of science fiction, regular Gizmag readers will know that it is now finding its way into real life – just within the past few years, scientists have demonstrated various experimental cloaking systems that prevent small objects from being seen, and in one case, from being heard. Such invisibility systems involve the use of metamaterials, which are man-made materials that exhibit optical qualities not found in nature. These are able to effectively bend light around an object, instead of allowing it to strike the object directly. Now, mathematicians from the University of Manchester are proposing technology based on the same principles, that would allow buildings to become “invisible” to earthquakes.  Read More

Cornell researchers have demonstrated a working temporal cloak that creates a gap in the f...

Last year researchers at Imperial College London proposed that along with being used to cloak physical objects metamaterials could also be used to cloak a singular event in time. A year later, researchers from Cornell University have demonstrated a working "temporal cloak" that is able to conceal a burst of light as if it had never occurred.  Read More

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

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.  Read More

Scientists have determined that it's theoretically  possible to create a spacetime cloak t...

Take some light bending metamaterials, incorporate them into flexible fabric and you have yourself an invisibility cloak. That's the theory anyway, and it doesn't stop at hiding objects. Building on the optical invisibility research of Professor Sir John Pendry, researchers from Imperial College, London, have now proposed that similar metamaterials could be used to conceal entire events – get ready for the "Spacetime cloak".  Read More

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