Nanowire-based light detectors work like gecko ears

Geckos and many other animals have heads that are too small to triangulate the location of noises the way we do, with widely spaced ears. Instead, they have a tiny tunnel through their heads that measures the way incoming sound waves bounce around to figure out which direction they came from.
Facing their own problem of minuscule size and triangulation, researchers from Stanford University have come up with a similar system for detecting the angle of in-coming light. Such a system could let tiny cameras detect where light is coming from, but without the bulk of a large lens.
“Making a little pixel on your photo camera that says light is coming from this or that direction is hard because, ideally, the pixels are very small – these days about 1/100th of a hair,” said Mark Brongersma, professor of materials science and engineering who is senior author of a paper about this system, published in Nature Nanotechnology (“Subwavelength angle-sensing photodetectors inspired by directional hearing in small animals”). “So it’s like having two eyes very close together and trying to cross them to see where the light is coming from.”
These researchers are working on tiny detectors that could record many characteristics of light, including color, polarity and, now, angle of light. As far as they know, the system they’ve described in this paper is the first to demonstrate that it’s possible to determine angle of light with a setup this small.
“The typical way to determine the direction of light is by using a lens. But those are big and there’s no comparable mechanisms when you shrink a device so it’s smaller than most bacteria,” said Shanhui Fan, professor of electrical engineering, who is a co-author on the paper.
More detailed light detection could support advances in lens-less cameras, augmented reality and robotic vision, which is important for autonomous cars.
Read more at nanowerk.com

Image Credit:    Shutterstock

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2018-11-09T02:47:03+00:00

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