Northwestern University researcher reveals cloak of invisibility


Northwestern researcher Cheng Sun is working on a 3-D cloaking deviceNorthwestern researcher Cheng Sun is working on a 3-D cloaking deviceImagine you’re alone in your room watching television. Suddenly, your annoying younger sibling disturbs your tranquility. He pelts you with popcorn, unplugs your television and breaks your favorite pen. You get up, and he cloaks himself with an invisibility device as he runs away laughing.

This may sound like an episode of the Twilight Zone or Star Trek, but Cheng Sun, an assistant professor in the mechanical engineering department at Northwestern University, is working to bring the concept of invisibility to fruition. While Sun will not be boarding the Star Trek Voyager anytime soon, he has been conducting his research for about a year and is completing the final stages of his 3-D cloaking device experiments. He is hoping to have his work published in an academic journal sometime in this summer.

What is meta-material science?

Meta, referring to the definition, is something that goes beyond the ordinary. The concept of meta-material is somewhat that all the material is made by atoms or molecules. So we want to create the same terminology. If a structure can be designed that the structure is much smaller than the wavelengths, so the wave would not be able to see individual building elements, but still we can design the properties that can be substantially different from the natural materials. Essentially, we’re creating man made or artificial crystals and material properties that never existed.

How did you get the idea for the cloaking device?

Initially, there was a theoretical paper published in the Physical Review Letters, and they were just giving a form letter to indicate the possibility that this could happen. Later, I think there were two or three papers published in a different publication. All those demonstrations were in the 2 dimensional. That’s the reason I became interested to see if this technology could work in a 3-D field. If I do the optical cloak, you definitely want to hide something of a certain size but if you only use 2-D technology it probably won’t work.

What can you share about your 3-D optical cloaking device?

It’s nothing special.  It can help to compensate the light on a curved surface. The light that comes out just appears to be not affected. In that case, it appears that light is reflected by a flat surface.

What are some of the uses of this research?

Generally if you want to hide something that could be a very useful technology. On the other hand, I think it is important to know how people can hide something. In this case, imagine you are working for the Transportation Security Administration. You would want to know how people could hide an object and would want to know the technology needed to counteract that kind of technology. I think it would be dangerous if the bad guy was able to get a hold of that technology without letting others know.

How will the 3-D cloaking device be similar to what has been shown on science fiction shows like Star Trek?

In terms of the final goal, it will be very similar. We’re basically taking a more realistic approach that hopefully will make the sci-fi adaptation of 3-D cloaking a little closer to being a reality in our lifetime.


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