A new imaging system could use opaque walls, doors, or floors as 'mirrors' to gather information about a given scene. The camera produced recognizable 3-D images of a wooden figurine and of foam cutouts outside of the device’s line of sight.

The principle behind the system is essentially that of the periscope. But instead of using angled mirrors to redirect light, the system uses ordinary walls, doors or floors — surfaces that aren’t generally thought of as reflective.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.

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Also: Learn about a wide-field imaging systemand rapid direction of optical zoom.