[Philip Lelyveld comment: watch the excellently produced 3 minute video for a quick understanding of how this works.]
[CNET / MIT Media Lab]
…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.
See the full article here: http://news.cnet.com/2300-11386_3-10011717.html
Learn more about the project here: http://web.media.mit.edu/~raskar/cornar/