Invisibility cloak how does it work

But with the cloak in place, the distortion was dramatically reduced. The device has another important limitation — it works only at a single specific frequency of microwave.

But Smith now hopes to build a 3D structure that could hide an object completely from view. So far, the technology works only in the microwave region of the spectrum. The problem with visible light is that it has a much smaller wavelength, meaning an optical metamaterial would have to be built on the nanoscale, which is beyond the limits of current nanotechnology.

It, too, would only work at a specific frequency. By Justin Mullins An invisibility cloak that works in the microwave region of the electromagnetic spectrum has been unveiled by researchers in the US. In order for us to see an object, light needs to reflect off it and hit our eyes. It's simple optics and this is the reason why we can't see black holes: Their intense gravity prevents light from escaping.

There have been several attempts at cloaking devices by projecting the light from behind the object in front of it, but the biggest problem with them up until now is that the object and the person viewing it had to be completely still in order for the illusion to work. However, scientists from the University of Rochester have found a somewhat simple way around this: They figured out a way to bend light around an object so it can move and still appear to be invisible to the viewer.

And all they need to make it happen is four standard lenses. The trick in making it work is figuring out the exact placement of the lenses and their magnification. Really, the panels and windowsills that appear behind the screen are images from the left and right parts of the shield being pressed together in the center, explains Joseph Choi , an optical engineer at Raytheon.

Cramer demonstrates this in his video by shining a laser through the lenticular material. The light goes in and is dispersed by the lens, then splits when it hits the object behind the screen.

From the front of the screen, the lenticular lenses distort and magnify this split in the light, stretching the images to either side of the object and pinching them together. The first version of the Quantum Stealth cloak was extremely simple: just one huge sheet of lenses running vertically.

Although Cramer largely disappears behind the screen, the cloaking was blurry and a little distorted. Version 2 improves upon the first —Cramer added a second piece of lenticular material to the back of the first. This creates a much clearer image, especially when the person or object is about 12 feet away.

Since that version, Cramer has cycled through at least a dozen other iterations of his Quantum Cloak. For a more recent version, Version 13, Cramer puts together two sheets back-to-back that are offset slightly from each other, creating an interference pattern in the light that obscures a target almost completely.

So if a person or a soldier were to stand behind a Quantum Stealth screen or hold it in front of them as a riot shield, from a certain distance away the soldier would seemingly disappear. There have also been plenty of legitimate, non-hoax attempts at invisibility cloaks and related tech. The military tech space is understandably intrigued by camouflage that actively adapts to the background.