An ultra-fast camera has captured a video of light as it bounces between mirrors. Although light isn't 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's 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 camera with a shutter speed of about a trillionth of a second to take pictures and video of a laser beam following a 3D path. Knowing exactly how long the pulse took to get to the camera, along with the pulse's trajectory in a flat plane, allowed a machine learning algorithm to reconstruct the entire 3D path of the burst of light.

An ultra-fast camera has captured a video of light as it bounces between mirrors. Although light isn't 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's 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 camera with a shutter speed of about a trillionth of a second to take pictures and video of a laser beam following a 3D path. Knowing exactly how long the pulse took to get to the camera, along with the pulse's trajectory in a flat plane, allowed a machine learning algorithm to reconstruct the entire 3D path of the burst of light.