Scientists record first footage of laser bullet

23 Oct 2014

A light pulse fired from a 10 TW laser, dispersing into water vapour. The blue glow is laser light. The source of the other colours is mainly plasma fibre (filament) arising as a result of ionised matter. Image via IPC PAS

A team of researchers in Poland have captured on film what fans of Star Wars have been waiting to see for years: a laser bullet.

While the concept of a laser bullet has been around for decades in science fiction, the science behind it means that in reality, it would be impossible to see with the naked eye.

In fact, the team from the Laser Centre of the Institute of Physical Chemistry in the University of Warsaw used a particular photography trick to capture the laser pulses. The only other way to record a pulse of light would require a camera that operates at billions of frames per second, which of course do not exist.

Explaining how they managed to capture the footage, the researchers said they used an adapted camera synchronised with the laser-generating laser pulses at a rate of about 10 shots per second and done in such a way that with every subsequent pulse, the camera recorded an image minimally delayed than the previous one.

A cross-section of light pulse beam with formed plasma filament. At the top is the appearance of several laser pulses passing through a cloud of condensed water vapour. Image via IPC PAS

The actual laser pulse only lasts about a dozen femtoseconds which, if you can get your head around, is a millionth of a billionth of a second. The laser pulse was so powerful it managed to ionise all atoms it came in contact with.

Explaining what people can see in their accompanying video, Dr Paweł Wnuk, who worked on the project said, “In fact, a different laser pulse can be seen in every frame of our film. Luckily, the physics always stays the same.

“So, on the film one can observe all the effects associated with the movement of the laser pulse in space, in particular, the changes in ambient light depending on the position of the pulse and the formation of flares on the walls when the light passes through the dispersing cloud of condensed water vapour.”

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Colm Gorey was a senior journalist with Silicon Republic