Cellphones could offer night vision

Posted by Staff writer

A University of Florida engineering researcher has developed a tiny night vision device that would be incorporated into everything from cellphones to eyeglasses and car windscreens.

The nickel-sized imaging device uses organic light-emitting diode technology similar to that found in cellphone or laptop screens for night vision. But unlike night vision goggles, which are heavy and expensive, the device is paper-thin, light and inexpensive.

"Really, this is a very inexpensive device," said Franky So, a UF professor of materials science and engineering. "Incorporating it into a cellphone might not be a big deal."

Standard night vision goggles use a photocathode to convert invisible infrared light photons into electrons. The electrons are accelerated under high voltage and driven into a phosphorous screen, producing greenish images of objects not visible to the eye in darkness. The process requires thousands of volts and a vacuum tube made of thick glass.

So's imaging device replaces the vacuum tube with several layers of organic semiconductor thin film materials. The structure is simple: It consists of a photodetector connected in series with an LED. When operating, infrared light photons are converted into electrons in the photodetector, and these photo-generated electrons are injected into the LED, generating visible light. The device – versions range from millimeter to nickel-size - currently uses glass, but it could be made with plastics, which would make it lighter weight.

Conventional night vision goggles or scopes weigh up to two pounds, with price tags ranging from hundreds to thousands of dollars. Sized for cell phones, So said, his imaging devices weigh just a couple of ounces and would be inexpensive to manufacture because factories could use the same equipment used today to make laptop screens or flat-screen televisions.