Digital cameras may soon get disabled via security systems that temporarily blind them. The process exploits a property of the image sensors used by digital cameras— namely, that they are retroreflective, sending light back directly to its origin rather than scattering it. Researchers at the Georgia Institute of Technology developed a prototype that uses light beams and cameras to scan areas for retroreflective dots matching sensors in shape. It then flashes a beam directly at those sensors, overwhelming them. Future versions might use infrared lasers at low, safe energy levels instead of light beams.

The camera-neutralizing technology could thwart clandestine photo graphy or tackle the $3-billion-a-year problem of movie piracy. It would prove ineffective against conventional film cameras, however, or single- lens reflexdigital cameras, which use folding mirrors that mask their sensors except when a photo graph is actually taken.