If cameras could see around corners, they could warn drivers of danger waiting around the bend, help firefighters search burning buildings and enable surgeons to see hard-to-reach areas inside the body. A few years ago researchers at the Massachusetts Institute of Technology's Media Lab figured out how to build such a camera, but it was an expensive early prototype. The device used a laser pulse to bounce light from a wall or door onto a stationary object in the next room. A $500,000 camera then recorded the light that bounced back, and software recorded the arrival time of individual photons, calculated distances and reconstructed the unseen object. Since then, the M.I.T. team has improved the technology significantly. Now it can record moving objects beyond the line of sight, and instead of a laser and a $500,000 camera, an LED and a $100 Microsoft Kinect sensor will do.

Illustration by Don Foley