Using superconducting nanowires and lasers, a new camera system can produce high-resolution 3-D images of objects from up to a kilometer away. The technology works by sending out a low-power infrared laser beam, which sweeps over an object or scene. Some light gets reflected back, though most is scattered in different directions. A detector measures how long it takes one particle of light, a photon, to return to the camera and is then able to calculate the distance from the system to the object. The technique can resolve millimeter-size bumps and changes in depth from hundreds of meters away.
The new camera takes advantage of superconducting nanowires, materials with almost no electrical resistance that have to be cooled to extremely low temperatures. These superconductors are very sensitive and can tell when just a single photon has hit them. "That's the beauty of this system," said physicist Gerald Buller of Heriot-Watt University in Edinburgh, Scotland, co-author of a paper on the system that appeared Apr. 4 in Optics Express. "Each laser pulse contains many photons, but we only need one photon to return for every 10 optical pulses."
The technology is similar to LIDAR, a remote sensing technique that also uses laser light to measure the distance to different objects. By using infrared light, Buller's camera is able to detect a wide variety of different items that don't reflect laser beams well, like clothing. And the long-wavelength infrared light is safer than other lasers because it won't harm people's eyes when it scans them.
Buller said the technology could have a lot of different scientific applications. The system could be placed on airplanes and used to scan the vegetation in a forest, helping to determine the size and health of the plants. The team is also interested in making the camera work well underwater, which would allow people to scan the depth of oceans or lakes and determine their shape.
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