Scientists at Heriot-Watt University in Edinburgh, Scotland have utilized ultra-high speed cameras to capture the flight path of of laser photons as they bounce off a series of mirrors, rather than just the visible dot detectable by the naked eye. Beams can be viewed by firing lasers into smoke or other opaque gas to give the photons molecules to reflect off of, but the effect is much more difficult to recreate in normal atmospheric air.
The team arranged the camera to film a side-on view of a green laser firing at an arrangement of mirrors. By firing 2 million pulses over a 10 minute period and subtracting background noise, they were able to build up enough air-scattered photons in the camera to track the laser’s path as it bounced.
via New Scientist