Femtosecond camera can peek around a corner

Photography is all about light. Typically, a lens is used to focus the light reflected from an object, striking a light-sensitive surface inside a camera to create an image recognizable to the human eye.

Until now, that light required a direct line of sight, but at MIT Media Lab's Camera Culture group, Ramesh Raskar and Andreas Velten have devised a new way of capturing light bouncing from around a corner -- a femtophotography. In traditional photography, the speed of light is infinite and does not play a role. The Media Lab's femtocamera, however, has a finite amount of time light takes to travel from one surface to another, which provides useful information.

Using a beam-splitter and what they call a femtosecond laser to send out a laser pulse that lasts less than one-trillionth of a second, the light returning from the scene is collected by a camera at the equivalent of close to 1 trillion frames per second, analyzed, and decoded to record the location, and ultimately shape of an object outside of the direct line of sight.