Researchers from Heriot-Watt University’s Extreme Light Group in Scotland have developed a camera that can see around walls to find objects that are hiding. “We can now track hidden objects in real time... and can picture them in considerable detail,” says Professor Daniele Faccio, from the University’s School of Engineering and Physical Science.
While previous object-detection methods that employed camera technology have demonstrated that it is possible to reconstruct the shape of an object hidden from view, these methods do not enable the tracking of movement in real-time.
The researchers demonstrated a compact non-line-of-sight laser ranging technology that relies on the ability to send light around an obstacle using a scattering floor and then detect the return signal from a hidden object within only a few seconds of acquisition time. According to the team’s paper, published in Nature Photonics, “By detecting this signal with a single-photon avalanche diode (SPAD) camera, we follow the movement of an object located a meter away from the camera with centimeter precision. We discuss the possibility of applying this technology to a variety of real-life situations in the near future.”
The camera system works by sending light from the camera toward the hidden object, then getting it back. When the team measured how long it takes for the light to return from the camera, it was able to get a sense of how far away the object was. The team then recorded the shape of the laser’s “echo” so that it could determine the direction it was coming from.
Since it only took about a second for the camera to record the information, the team was able to track objects in real-time – even if it was moving. “The ability to detect the 3D shape of static, hidden objects has been demonstrated before, but the long acquisition time required by existing methods meant locating and monitoring the objects was a major challenge,” says Professor Faccio.
Now that they’re capable of tracking objects, the researchers are going to explore further how the light identifies the objects and is able to picture them in detail. “We’ve already increased the distance from which the camera system will work, which is over several meters. We’re also focusing on how we could attempt 3D reconstruction of the objects captured by the camera,” adds Faccio.