An ultra-fast camera has captured a video of light as it bounces between mirrors.
Although light isn鈥檛 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 pulse鈥檚 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 a聽camera with a shutter speed of聽about a trillionth of a second to聽take聽pictures and video of a laser聽beam following a 3D path.
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Knowing exactly how long the pulse took to get to the camera, along with the pulse鈥檚 trajectory in a flat plane, allowed a machine learning algorithm to reconstruct the entire 3D path of the burst of light.
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This could be useful in chemistry, says Marty Baylor at Carleton College in Minnesota. 鈥淵ou could watch light interacting with a molecule in real time鈥�, 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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