F. Sorin et al., Nano Letters, Online edition (2009)

All seeing. Light-sensitive detectors drawn into very thin fibers can produce images (inset) without the need for lenses.

Futuristic Fibers Could Replace Camera Lenses

Picture a wall that stares back at you. Or a uniform that shows a soldier a 360-degree view of the battlefield. Both scenarios are possible courtesy of a new generation of flexible, translucent fibers developed by researchers at the Massachusetts Institute of Technology (MIT) in Cambridge. These so-called multimaterial fibers can turn incoming light waves into images without the need for a camera lens. And unlike fiber optic cables, they can transmit images that have been captured across their entire length.

Current cameras rely on lenses to produce a recognizable image. The curved glass or plastic of a lens focuses light waves reflected off an object onto a surface that can display the resulting images, either film or, in the case of digital cameras, charged-coupled devices. The idea has worked well for decades, but it's always contained an Achilles' heel: Damage the lens, and you lose or diminish the ability to see.

The multimaterial fibers developed by the MIT team could solve this problem and provide a host of other benefits. The fibers consist of an array of metal electrodes connected to a semiconductor and are covered by an insulating polymer sheath. The semiconductor layer in the fiber detects light and relays signals via the electrodes to a microprocessor, which combines the signals from an array of the fibers to determine the light's intensity, direction, and color. Visualization software then takes that data and recreates the source image and displays it on a monitor screen. And the whole process is accomplished without a lens.

In experiments reported online this week in Nano Letters, the MIT researchers were able to create an image of a smiley face on a video screen by placing a web of the fibers in front of the drawn image. They also demonstrated how the multimaterial fibers could be woven into an optical fabric--a flexible camera--that could serve as stealth wallpaper or be incorporated into a soldier's uniform to scan the battlefield in all directions and send images to a video monitor in the soldier's helmet.

Materials scientist and co-author Yoel Fink says the technology eliminates the drawback of lenses by allowing the entire surface area of the fabric to collect images. So if one part gets damaged or degraded, the remainder can still function.

It's an interesting concept that "should inspire others to find ways to integrate nanoscale components," says materials scientist Rod Ruoff of the University of Texas, Austin. "I found myself wondering, for example, whether such components might conceivably be embedded in glass fibers, as well as in polymer fibers."

Posted in Technology