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Optics and photonics

The laser-based apparatus receives a steady drip of single photons to craft portraits of distant targets.

A remote-sensing device can transform a trickle of incoming photons into a high-fidelity image of an object more than 200 kilometres away. Similar technology works over distances of only tens of kilometres.

In the imaging method called lidar, a device fires a laser at a target and analyses the reflected light. The longer it takes light to make a round trip, the greater the distance. By combining the data from many incoming photons, lidar systems can build up a 3D profile of the target.

Pan Jianwei, Xu Feihu and their collaborators at the University of Science and Technology of China in Hefei built a type of single-photon lidar device that sends and receives one photon at a time. The researchers’ system relies mainly on off-the-shelf components, but its custom light sensor detects single photons with high efficiency and low noise. To improve accuracy, the device uses just one telescope, which both shoots light at the target and collects the reflected photons.

The device’s high penetration through the atmosphere makes it suitable for long-distance airborne sensing, the authors write.

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