An ultra-fast camera has captured a video of light as it bounces between mirrors.
Although light isnāt normally visible in flight, some photons from a laser pulse will scatter off particles in the air and can be picked up by a camera. Using these photons to recreate the pulseās trajectory is difficult, because by the time they reach the camera, the pulse has moved to a new location.
Edoardo Charbon at the Swiss Federal Institute of Technology in Lausanne and his colleagues used aĀ camera with a shutter speed ofĀ about a trillionth of a second toĀ takeĀ pictures and video of a laserĀ beam following a 3D path.
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Knowing exactly how long the pulse took to get to the camera, along with the pulseās trajectory in a flat plane, allowed a machine learning algorithm to reconstruct the entire 3D path of the burst of light.
[video_player id=āORa3W5Cyā access_level=āeveryoneā]
This could be useful in chemistry, says Marty Baylor at Carleton College in Minnesota. āYou could watch light interacting with a molecule in real timeā, giving a more detailed understanding of certain chemical reactions, she says.
A similar method could also be used to see around obstacles, says Charbon. If you bounced a laser pulse off a wall, then off an obscured object around a corner and back off the wall again before capturing it, the algorithm could potentially reconstruct an image.
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