MIT Researchers Developing Camera That Sees Around Corners

Posted on March 21, 2012

MIT Media Lab researchers are developing a camera that can see round corners. The researchers have used their system to produce recognizable 3-D images of wooden figurines and foam cutouts outside their camera's line of sight. The researchers say the principle behind the system is similar to the periscope. But instead of using angled mirrors to redirect light, the system uses ordinary walls, doors or floors - surfaces that are not typically thought of as reflective. The system uses a femtosecond laser to bounce light off walls and doors. Here is MIT's description of the camera:
The system exploits a device called a femtosecond laser, which emits bursts of light so short that their duration is measured in quadrillionths of a second. To peer into a room that's outside its line of sight, the system might fire femtosecond bursts of laser light at the wall opposite the doorway. The light would reflect off the wall and into the room, then bounce around and re-emerge, ultimately striking a detector that can take measurements every few picoseconds, or trillionths of a second. Because the light bursts are so short, the system can gauge how far they've traveled by measuring the time it takes them to reach the detector.

The system performs this procedure several times, bouncing light off several different spots on the wall, so that it enters the room at several different angles. The detector, too, measures the returning light at different angles. By comparing the times at which returning light strikes different parts of the detector, the system can piece together a picture of the room's geometry.
Ramesh Raskar, an associate professor at the MIT Media Lab, who led the new research, believes the system could be used by emergency responders, such as firefighters looking for people in burning buildings or police determining whether rooms are safe to enter.

Here is a video demonstration:

The research was published here in the journal Nature Communications.

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