This fence is not as advertised, sir.
The last time we wrote about invisibility cloaks was when metamaterials were used to conceal all of the visual spectrum except violet. Now two different research teams have discovered that a much simpler material can be used to cloak objects. The team at MIT concealed a piece of metal the size of a peppercorn and the team at the University of Birmingham went even larger, concealing a paperclip. They used two naturally-occurring calcite crystals with opposite crystal orientations:
The researchers constructed their cloaks from two glued-together calcite crystals, which have a convenient optical property called birefringence–that means they can bend a ray of light in two different directions. Then they placed the objects to be concealed in a notch beneath the crystals. [80beats]
The good news is calcite crystals as large as 23 feet long have been found in nature. The bad news is it only works under one light polarization, meaning — although it works at all angles — the light source has to be aimed dead-on. The picture to the right shows how the calcite crystal setup wor– oh, there’s Waldo! That cheating bastard.
I want more like this!
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