Researchers at the Massachusetts Institute of Technology are using a device that bounces a laser off doors and walls to create three-dimensional images of what is out of sight.
For example, to create images inside a room around a corner, the device fires a femtosecond laser that emits bursts of light measured in quadrillionths of a second at the wall or ceiling outside the room. Some of the laser beam reflects off that surface and into the room, where it continues to bounce off objects and walls. Some of the light reemerges and strikes a photodetector that takes samples every few picoseconds (trillionths of a second). Like radar, the device measures the time it takes for reflections to return, which lets it calculate how far the beams have traveled.
The device repeats this process several times, angling the laser off different spots on the wall. Travel times from several laser bursts are assembled using various algorithms, including filtered backscatttering, a technique commonly used in CAT scans. This lets the device piece together the geometry of the room. In tests, images are said to be blurry but easily recognizable.
Once improved, the device could be a tool for police or firefighters trying to determine if it‘s safe to enter a room. It could also be used by a vehicle’s nav system to peer around corners, and in medical endoscopic cameras to see otherwise hidden areas inside the human body.