By Michael Kanellos

http://news.com.com/Crave+privacy+New+tech+knocks+out+digital+cameras/2100-7337_3-5869832.html

Researchers at the Georgia Institute of Technology have come up with
an inexpensive way to prevent digital cameras and digital video cameras
from capturing that secret shot.

The technology they’ve devised detects the presence of a digital camera
up to 33 feet away and can then shoot a targeted beam of light at the
lens, according to Shwetak Patel, a grad student at the university and one of the lead researchers on the project.

That means that someone trying for a surreptitious snapshot of, say, a
product prototype or an amorous couple gets something altogether less
useful–a blurry picture (or a video) of what looks like a flashlight
beam, seen head on. (A video of how the system works can be viewed here.)

How it works
The Georgia Tech system essentially exploits the “retroreflective”
property of digital camera lenses. When light strikes a retroreflective
surface, a portion of the light bounces back to the original source.
While eyeglasses, bottles, watches and other glass surfaces are
retroreflective, a coating on virtually all digital camera lenses puts
cameras in a class of their own.

“The film atop lenses (is) highly reflective,” said Patel. “A lot of
people probably have known this but they haven’t thought about
leveraging it.”

In this system, a device bathes the region in front of it with
infrared light. When an intense retroreflection indicates the presence
of a digital camera lens, the device then fires a localized beam of
light directly at that point. Thus, the picture gets washed out.

The neutralizing light continues until the camera lens can no longer be
detected, which prevents video cameras from capturing clear footage.

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