The Future is Here: The Invisibility Cloak!

quantum-stealth-fieldInvisibility cloaks have long been considered the next frontier of modern warfare. With stealth aircraft, stealth ships and even stealth tanks in service or on well on their way, it seems like the time is ripe for a stealth soldier. But difficulties remains. Whereas cloaking planes, ships and tanks is a matter of simply coating them in materials that can obscure them from radar and thermal imagine, soldiers need camouflage that can move, bend and flex with them.

In recent years, the efforts to produce a working “invisibility cloak” have born considerable fruit. And while most of these took the form of large, cumbersome, desk-mounted constructions that were more of a proof of concept for the material being tested, they did demonstrate that the technology itself worked. This was certainly true of the “cloak” which was created by scientists at Duke University in November of 2012.

INVISIBILITY-CLOAKAnd then came news the following month that a Canadian company named Hyperstealth developed a material that renders the wearer “completely invisible by bending light waves around the target.” Known as “Quantum Stealth”, this true cloak is an apparent follow-up to their SmartCamo – a material that could reportedly adjust its camouflage markings to match its surroundings – that was released at the International Camouflage Symposium in 2010.

Unfortunately, due to security reasons, little was ever known about SmartCamo other than its reported abilities. The same holds true for Quantum Stealth, which the company has been forced to remain clandestine about due the demands of the US Army, to whom they are contracted. So until such time as it enters widespread use, the details and inner workings of the technology will remain inaccessible.

invisibility_cloak1Luckily, the University of Texas in Austin is under no such constrictions, and it is from them that the latest and greatest news comes. In addition to being composed of conventional materials, their new cloak measures a mere 166 micrometers thick and is capable of obscuring an object from multiple directions at once. And though it may not be able to render a soldier truly invisible, it does render them all but invisible to radar detection, which is the intent here.

The fabrication process involved placing a 66µm-thick sheet of carbon (or a metascreen) onto a a 100µm-thick sheet of flexible polycarbonate. The copper is patterned specifically so that the scattered light from the cloak and the cloaked object cancel each other out. This flexible sheet also allows the cloak to conform to the shape of the object, or person, and provides cloaking from microwave radiation from all directions.

invisibility_cloak_uoftNow here’s where things get literal. The researchers responsible for this breakthrough have indicated that, in theory, this cloak could be used to cloak visible light as well. After all, microwaves, infrared and visible light are all physically identical; they are just waves that oscillate at different frequencies. And their design would be more capable of doing this than any cloak composed of metamaterials.

Still, size and scale are still an issue. Whereas their new patterned material scattering technique is capable of hiding an object from multiple directions, it also inversely scales with wavelength. That means that it is only capable of hiding micrometer-scale objects from 400-800THz of visible light. Still, this is exciting news and a step in the right direction!

Before we know it, stealth troopers could be marching all over the planet, invisible to the naked eye and any means of radar detection… Holy crap, what a scary thought! Is it too late to rethink this technology?

future_soldierSource: Extremetech.com, (2)

The Future is Here: Invisibility Cloaks (Cont’d)

An update on the ongoing efforts to create invisibility technology has been bearing some pretty interesting fruit. Earlier this year, scientists at Berkeley announced that they were working on a suit that would be capable of bending light around it. Unlike adaptive camouflage, this technology would not merely broadcast a background image to conceal a soldier, but would render them virtually invisible to the naked eye.

Well guess what? Scientists at Duke University have finally created a cloak that works. Granted, it is only capable of concealing objects on the centimeter-scale, it is the only cloak of its kind that is capable of channeling incident light around itself, creating perfect invisibility. In all previous cases, the devices created reflected a certain degree of incident light, leaving the concealed object disguised but discernible.

In addition to the small scale on which it functions, the cloak has a few additional drawbacks. For now, the Duke invisibility cloak only works with microwave radiation; and perhaps more importantly, the cloak is unidirectional, meaning it only provides invisibility from one very specific direction. But that should hardly matter, seeing as how such a device even exists. With a little time, development, and a big fat DARPA contract, soon we may be seeing cloaking devices that are capable of concealing something as large as a person, a vehicle or even a building.

The Duke cloaking device, pictured at left, is composed of metamaterials – an artificial, man-made material that almost always have a negative refractive index. A negative refractive index allows for the creation of some interesting things, such as superlenses that go beyond the diffraction limit; or in this case, invisibility cloaks. Due to their unusual index, they are capable of refracting light around an object so a viewer does not see the object, but what is behind the object.

But in addition to metamaterials, the compositional materials also need a to be arranged in such a way that the illusion is perfect. After all, a 3D object has multiple sides, and the wearer has to be expected to turn a corner and change direction at some point. All previous designers in this case have struggled to fashion metamaterials that bend waves around corners without causing reflections. In this case, it was researcher Nathan Landy, a Duke University student, who arranged the metamaterials into the shape of a diamond to acheive the desired effect, since diamonds are apparently the best shape for minimizing reflections.

According to the Duke team, the next step is to expand on their design and make their cloak omnidirectional, meaning that it can bend light around the object from all directions. Don’t worry, I’m thinking some rather interested parties (i.e. every high-tech developer and military on the planet) is likely to be knocking on their door real soon!

Source: Extreme Tech