Invisibility Cloaks: Fact or Fiction?

Subject: Invisibility Cloaks: Fact or Fiction? Sun Aug 21, 2016 11:30 pm

From Ancient Greek myths to the Harry Potter series, cloaks of invisibility have wooed imaginations and inspired daydreams. Heroes, villains, giants, and fairies have donned this mythical mantle in folklore and fantasy, fascinating readers and researchers alike. In fact, many researchers have tried to push the limits of physics to hide items and people from view.

Invisibility Cloaks: Fact or Fiction? X354-q80

Invisibility Cloaks: Fact or Fiction? X354-q80

Although recent studies suggest that making a real invisibility cloak is possible, several major challenges have thwarted its creation. Now, writing in Optica, researchers explain the physical limits of electromagnetic “invisibility” cloaks for objects of different sizes and present a quantitative framework to direct the design of future invisibility efforts.

Studying Human-sized Cloaking

“The question is, ‘Can we make a passive cloak that makes human-scale objects invisible?’” said University of Texas electromagnetics researcher Andrea Alù in a press release. “It turns out that there are stringent constraints in coating an object with a passive material and making it look as if the object were not there for an arbitrary incoming wave and observation point.”

Cloaking makes items invisible by not only hiding the object but also by showing what is directly behind the object. More technically, cloaking takes the light coming from behind an object, guides it around the object, and brings it toward the viewer, making it look like the object was never there. Making something invisible means making it transparent under visible wavelengths. However, the visible spectrum is only a tiny part of the overall electromagnetic spectrum.

To define the specific limits of cloaking, Alù partnered with graduate student Francesco Monticone to develop a theory confirming that cloaks could hide an object completely at a specific wavelength. Using this quantitative framework, researchers now can calculate the functionality and performance of passive invisibility devices, in terms of bandwidth and expected scattering reduction, before actually constructing a specific design.

http://www.biotechniques.com/news/biotechniquesNews/biotechniques-364962.html#.V7jUeWXrCPI

Invisibility Cloaks: Fact or Fiction?

Invisibility Cloaks: Fact or Fiction?

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