Get Ready For Halloween — DIY Invisibility Cloaks Are Closer Than You Think

2014-09-11-howell-cloaking-164-crop-630x420Photo: Courtesy of University of Rochester
It's not even October yet, and we're already getting into the swing of Halloween. In a similar spirit, a few researchers at the University of Rochester have now brought us a Harry Potter-inspired, low-tech cloaking device.
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In their paper, the researchers describe using an arrangement of three or four off-the-shelf lenses to cloak an object (such as a ruler or their hand) without altering the appearance of the gridded lines behind it. Essentially, each lens has its own focal length, causing light to bend around the object as it passes through the lens. The end result is that the object is cloaked, but the stuff around it isn't. Even if the observer moves a few degrees up or down from the optimal viewing position, the target object will still be obscured. It might not be a 360-degree, wearable cloak, but we're getting there.
Previous "invisibility" devices have either not really made you invisible or have only made you invisible from a particular angle. This one gets around those limitations by using ray optics and prioritizing accessible components. And, because it doesn't require any of the fancy equipment required for other devices, you can make your own with the researchers' handy instructions. So, go ahead and pretend to be Sue Storm — just make sure your three fantastic friends have your back, because you won't quite be invisible from every angle.
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