Human eyes are good, but if you want a panoramic view or the ability to track moving objects, compound eyes like a fly's are the way to go. Not only can they see in all directions, but there's actually less distortion - and insects can cram all that into a tiny space.
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That ability to see in all directions and pick up on motion easily would be really useful for robots, driverless cars, and 3D imaging. So a team at the Swiss Federal Institute of Technology (EPFL) built an artificial version.
It isn't as easy as it sounds, though. The light sensors, lenses and electronics all had to be smaller than anyone has made them before, and in order to shape the artificial eye the printed circuit had to be flexible.
To accomplish this the group, led by Dario Floreano, designed three layers. One is a microscopic array of lenses, the next is a light-sensitive array that mimics the circuitry of an insect brain, and a flexible printed circuit board that provides structural support and handles signal processing. They put it in a tiny curved, thin package, so that they would get a field of view comparable to that of a fly. It's curved so that the light-sensors an fit around the electronics. "Just like compound eyes of insects are wrapped around their brains," Floreano told Discovery News.
The device gives a near-panoramic, undistorted view. Floreano added that it can pick up motion at 150 frames per second, and work in anything from bright sunlight to moonlight, adapting to a new level of illumination in in a millisecond.
One reason for duplicating the inset eye is size and weight. There are a number of designs for flying, autonomous robots – such as the tiny robo-fly. But they can't always see well, because the amount of light a single lens can take up is directly proportional to its size. A compound eye combines lots of small lenses, simulating a bigger one – and offering the 180 degree field of vision flies are famous for (especially when trying to sneak up behind them).
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A robot compound eye on a small, flying drone could see motion better than a single lens, and that's important when you're flying around with other moving objects.
The work is in the current issue of Proceedings of the National Academy of Sciences.
Image: courtesy Dario Floreano / Swiss Federal Institute of Technology