"Deployable" invisibility screens have been around for some time, able to make an object invisible from one direction, but these objects have extremely limited applications, considering they only work in theory in extremely controlled environments. It seemed for a while the world of ground stealth technology would have to remain in the realm of science fiction and fantasy, but now scientists have developed a system which can conceal an object from any direction in 3D. The world may soon have a true invisibility cloak.
The study, being led by Tolga Ergin, of the Karlsruhe Institute of Technology in Germany, uses a carpet-like material to capture light and bend it around an object, and come out the other side. To understand better how the principles work, we can illustrate the principle using the basic fundamentals of exactly how seeing works. Light comes from a source, and is bounced off an object, having certain spectrums of its energy absorbed by the object. As the light bounces off, the thing we are seeing reflecting the light is visible. The only way something could be invisible, would be if light either passed through it entirely (like a perfectly clean window) or the light hitting the object passed around it, but then projected back in a way that indicated nothing was there. To absorb all light hitting an object would make it appear as a shadow. We may not be able to observe details, but we could easily tell that something was there. True invisibility could only come about as a result of a perfect screen that bent all light that hit it and sent it back the way it came.
The previous principle behind invisibility was to take tiny rods and drill them so that the light would bend through and pass from one end to another. The light source, as well as the observer, had to remain in one position in order for this to work. The new material, however, uses light itself as the tool to alter it, reacting in such a way that it will be warped into the perfect position regardless of the light source's position and the position of the observer using a photonic material.
Early invisibility cloaks would likely be large heavy suits, but eventually as materials are made as small as 20 nanometers, the photonic material could eventually be a thin clinging fabric that could have field applications and, unfortunately, applications for criminals as well. Of course looking at the principles discussed in the material, there are a few immediate countermeasures that come to mind. Since the material itself simple bends light, rather than making a subject incorporeal, a suit would have to be exceedingly clean and dry at all times, or else a ghostly outline would be visible. The suit may not work as well in extremely dimly lit areas, and unless it found a way to hide the body heat of the user entirely, the subject would still show up on infrared imaging systems. In addition, it would be impossible for a subject to see while in such a suit, as light would bend around them, and not reach the eyes.
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