A bug's eye can see in almost every direction at once. Such broad vision holds tremendous appeal for the makers--and users--of artificial lenses. But current options rely on the so-called fish eye, an array of multiple lenses that must be precisely configured to produce an image. Now researchers have fabricated an artificial eye that mimics an insect's compound eye--from the lens through the light channel and down to the receptor.
Bioengineer Luke Lee of the University of California, Berkeley and his colleagues first constructed a mold, consisting of thousands of microlens shapes--no more than three micrometers wide--arrayed in a honeycomb pattern. They coated the mold in an epoxy resin that hardens when exposed to ultraviolet light. The resin formed a surface of more than 8,700 raised mounds--the microlenses--in a broad, rounded shape. Each lens allows a slightly different bit of light to penetrate, focusing it into the interior of the resin.
Because of the resin's sensitivity to ultraviolet light, it forms tiny channels over time, configured exactly to the alignment of the microlenses themselves. This allows a broad image as well as the perfect alignment of the microlenses, channels and receptors, just as in the ommatidium (individual units) of a bug's eye. "Who knows? Maybe this is how insect eyes are created too," Lee speculates. "First, there are the lenses and then, as light keeps coming in, they make their own optical paths and connect with the visual system."
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The process requires no high temperatures or precise etching and the mold can be reused, according to the paper presenting the method in today's Science. In a few years, such all-seeing lenses could be found in camera phones, at the end of medical devices, in omnidirectional surveillance systems or as tiny, hidden cameras, Lee says. Panoptic living may finally be glimpsed through a fly's eye.
