Chinese scientists develop laser that can spot hidden object from more than a kilometre away
- Previously it was only possible to find things a few metres away by using non-line-of-sight imaging but the range has now greatly expanded
- The technology could be used to help self-driving cars spot other vehicles and pedestrians or help law enforcement
Chinese scientists have developed a way to see an object hidden behind a screen more than a kilometre away.
They said the technique, known as non-line-of-sight (NLOS) imaging, could be used for everything from defence and policing to transport.
The team of scientists at the University of Science and Technology of China set up a laser emitter at their university campus in urban Shanghai and hid a mannequin behind a screen inside a flat 1.43km (0.89 miles) away, according to a paper published earlier this month in the Proceedings of the National Academy of Sciences.
The researchers projected a pulsed laser onto a wall inside the flat, which then scattered in multiple directions. Some of the light particles, or photons, were reflected on to the hidden mannequin and some others travelled to a sensor located next to the laser emitter.
The photons that hit the mannequin were then reflected back onto the wall and bounced back a third time to hit the sensor.

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Chinese scientists use lasers to ‘see’ around corners over 1km away
By analysing the travel duration of light that bounced against the wall once –compared with light that bounced between the wall, the mannequin and the sensor – the researchers were able to calculate how far the each part of the mannequin was positioned from the wall and reconstruct a fuzzy, three-dimensional image via an algorithm.
