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Invisibility

A new invisibility cloak developed at the Karlsruhe Institute of Technology (KIT) is reportedly able to hide any object that can fit inside a one-inch diameter cylinder. The cloaking device is among the first to rely on common materials like polymers and acrylic paint, and could be used for a practical demonstration of cloaking technology.

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Two scientists at the University of Rochester have taken invisibility cloaking back to basics. Their novel arrangement of four standard, off-the-shelf lenses keeps an object hidden (and the background undisturbed) as the viewer moves up to several degrees away from the optimal viewing angle. Read More
Scientists at Karlsruhe Institute of Technology have developed a method of concealing objects from the sensation of touch that would finally meet the exacting standards of Hans Christian Andersen's fairy tale princess, who felt a single pea prodding her beneath 20 mattresses and 20 feather beds. Read More
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
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
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
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
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
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
When we think of invisibility cloaks, probably the first things that come to mind are Harry Potter-like contraptions that allow people or large objects to instantly disappear. Scientists from the University of Maryland and nearby Towson University, however, today announced their development of something a little different – little being the key word. They have crammed 25,000 tiny “invisibility cloaks” onto a gold sheet, which itself only measures 25 millimeters per side. While the resulting biochip array may not allow any young wizards to vanish from sight, it could allow them to identify biological materials. Read More
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