Scientists in China have developed a laser that can see an object that’s hidden behind a screen more than a kilometre away. The technique is dubbed NLOS or non-line-of-sight imaging and it could help self-driving cars get better in future. The technology (published in Proceedings of the National Academy of Sciences) was developed by a team of scientists at the University of Science and Technology Of China. They installed a laser emitter at their university campus in Shanghai and roughly 1.43 kilometres away, they hid a mannequin behind a screen.
The scientists then flashed a pulsed laser onto a wall inside the flat which then dispersed into several directions. Many light particles reflected on the hidden mannequin with some travelling to a sensor located next to the laser emitter, nearly two kilometres away.
The light particles or photons that managed to hit the mannequin were then reflected back to the wall and bounced back for the final time before they hit the sensor. Analyzing the time it took for the light to bounce against the wall once researchers were able to figure out how far each part of the mannequin was positioned from the wall in a rather strange 3D image with the help of an algorithm.
They were able to locate the hidden object based on a photon’s travel time as the speed of light is constant. This was also capable of determining different objects placed around 9.4 centimetres apart.
To tackle the issues that are normally encountered due to distance, scientists fabricated a laser emitter and sensor to use different telescopes that limited signal interference between them. Moreover, the sensor was equipped with multiple lenses to prevent stray light from affecting laser light particles while it returned from the flat.
Researchers in the study reveal that this feat is three times longer than what was previously achievable, this range is about three orders of magnitude longer than previous experiments. The results will open avenues for the development of NLOS imaging techniques and relevant applications to real-world conditions.
Researchers state that this technology could help self-driving cars better detect other cars, pedestrians that are behind buildings. Moreover, it could also be helpful for law enforcement to detect hostages in an unpredictable area to be better prepared.