Scientists create cloaking technology, make Harry Potter jealous

The stealthy B2 Bomber uses advanced stealth technology based on wave dynamics to hide from the enemy. Future advances may allow aircraft to appear completely hidden.

Remember when you first saw Harry Potter's invisibility cloak and your childhood imagination imploded? It turns out that science is making great leaps in the field of transformation optics, and we may not be too far away from a Harry Potter-esque invisibility cloak. Unfortunately, this latest tech is no perfect cloak, but it's the next best thing.

Until now, most cloaking technologies worked by using illusion optics which traditionally uses a two-fold operation to cloak an object. When you look at an object, electromagnectic waves hit the object and excite electrons, and light gets reemitted from the object. This creates a specific scattering signature—an image of sorts that's similar to what a radar would create—which in turn allows us to differentiate between one object and another.

In two-fold illusion optics, the light (or other electromagnetic radiation) hitting the object to be cloaked interacts with a special metamaterial, eliminating the scattering that would normally be caused by the object. The electromatic waves (like light waves) need to go somewhere, so the metamaterial creates your desired scattering signature (this can be anything from a different object's image, to the background behind the object). In other words, this process cancels the old light-scattering signature and creates a new one.

This two-fold method is extremely difficult to pull off with current technology capabilities and may result in large losses in the illusional performance (meaning that there may be gaps in the cloak or other faults that make it a poor illusion and easier to identify). If you are trying to completely hide an object, this is obviously a problem.

To address this concern, several university researchers built a device that transforms the scattering signature of a real object into three or more scattering signatures (one new but different image of the original object and at least two ghost images off to the sides of the original object). This new method only uses a single-step process that directly metamorphosizes the scattering to a new pre-determined pattern.

The researchers call this new technology a ghost cloak. Instead of making it look like the object isn't there, this technology can make it look like there are multiple objects in place of the original object.

"Creation of Ghost Illusions Using Metamaterials in Wave Dynamics" on arXiv
Object radar images with and without cloak.

In the figure above you can compare an original object (a) with its radar image (d), the designed ghost device which fits over the original object (b) and its radar image (e), and the original object with its ghost images (c) and its radar image (f).  As you can see, the "ghost" technique gives off a radar image that is completely unlike the radar image of the original object by itself.

The researchers say that this work in wave dynamics may help in the fields of light-matter behavior control and security enhancement. I can see where this would be useful in the military where they might want to mask a secret vessel with something that seems less irregular.

To learn more about this research and about how the actual device that they built works make sure to check out the full paper on arXiv (Cornell University Library).

[arXiv via MIT Technology Review / Top photo: Mr Fujisawa/Flickr (CC BY-ND 2.0)]

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