MIT camera can see around corners

Posted by Emma Woollacott

MIT researchers say they've developed a camera that can see round corners - useful for peeping toms and rescue workers.

It's been working on such a system for some time; and has now revealed that its trillion-frames-per-second camera, announced late last year, was part of the same development effort.

The new camera, they say, is good enough to produce recognizable 3D images of a wooden figurine and of foam cutouts outside the camera’s line of sight.

It works on the same principle as a periscope, but does without the angled mirrors to redirect light, instead using ordinary walls, doors or floors — surfaces that aren’t generally thought of as reflective.

The system is based on a femtosecond laser, which emits super-short bursts of light. To see into a room that’s outside its line of sight, it could fire the laser at the wall opposite the doorway.

The light would reflect off the wall and into the room, bounce around a bit and re-emerge to strike the detector; and the time taken for this can indicate how far the laser bursts have traveled. After the procedure's been carried out several times at different angles, the system can piece together the room’s geometry.

The team's tested the camera by firing femtosecond bursts of laser light at an opaque screen, which reflected the light onto objects suspended in front of another opaque panel. And, they say, the 3D images produced were blurry but easily recognizable.

It could be used, they say, by emergency responders or by vehicle navigation systems, which could bounce light off the ground to look around blind corners.

The real innovation, says Andrew Fitzgibbon of Microsoft Research, was the audacity to have a go.

"Coming at it from both ends, from the raw scientific question — because, you know, it is kind of a scientific question: ‘Could we see around a corner?’ — to the extreme engineering of it — ‘Can we time these pulses to femtoseconds?’ — that combination, I think, is rare," he says.