Scientists Photograph a Light Pulse
Researchers have taken a photograph of a light pulse that is just 2.5 femtoseconds (10^-15 seconds) long - the shortest pulse ever to be imaged.
They didn't use a tiny camera, but rather another even shorter light pulse. This flash lasted just 80 attoseconds (10^-18 seconds), making it the shortest light pulse ever generated.
The new record soundly beats the previous record of 130 attoseconds, set in 2007. But researcher Eleftherios Goulielmakis at the Max Planck Institute for Quantum Optics hopes that, in the future, his team will be able to generate light pulses as short as just 24 attoseconds. This is the time it takes an electron to travel across a hydrogen atom, and is known as the atomic unit of time.
But even the atomic unit of time is not an ultimate limit. It may be possible to generate zeptosecond (10^-21 seconds) light pulses. These light pulses would be so fast that they could take images of protons moving around in an atom's nucleus.
The scientists' method for taking the photograph of the 2.5-femtosecond laser pulse involved firing the pulses at a cloud of neon gas. Each laser pulse consists of just one or two wavelengths of a light wave, so their compactness means they can pack quite a punch when hitting the neon atoms.
The laser pulses cause the neon atoms to release 80-attosecond ultraviolet light pulses. Then the scientists directed these ultraviolet pulses to a second cloud of neon gas, where they were intense enough to release an electron from the neon atoms.
Finally, in a roundabout way, the researchers could use these electrons to illuminate ("photograph") the original 2.5-femtosecond laser pulses.
In the future, researchers could also use the 80-attosecond light pulses as a sort of "electron camera," where they could take images of electrons moving around larger atoms.
The study is published in a recent issue of Science .
via: New Scientist