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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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.
