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Fastest-Ever Flashgun Captures Image of Light Wave
loconet writes to tell us that a team of researchers have created the shortest-ever flash of light. Weighing in at just 80 attoseconds, this flash has already been used to capture an image of a laser pulse and could possibly be used in the future to capture the electron movement around large atoms.
From the article it sounds like a pump-probe experiment. They excite the neon with a 2.5 femtosecond pulse and then image the excited state with a 80 attosecond pulse. (You obviously need the imaging pulse to be shorter than the excitation pulse.) I'm not sure how much detail you would be able to get from this though, as the wavelength and brightness of the light source would be a limiting factor.
Ok, first you have this coherent photon beam. This means that they are all traveling at the same direction. So how do you take a picture of THAT?
In a different way that a standard photograph.
You are bombarding the photon beam with photons,
No, you aren't. That doesn't make sense.
What they do is have the laser pulse travel through something they call a "chirped mirror". This packs the photos from the laser pulse into a smaller space. This then travels through a neon cloud, which then creates a flash of light. This flash of light is the "shortest-ever flash of light".
To photograph this flash of light, they direct it into a second neon cloud, which ionizes atoms, releasing electrons. Those electrons are then recorded. Multiple flashes were required to produce enough electrons to build up the image shown in the article, so what you really have is an image of many flashes overlaid.
Consider a 35mm film camera with a mechanical shutter... what degree of force and mechanism would be required to move that shutter to open AND close the height of 24mm in 80 attoseconds? IANAPhysicist, but I doubt human hands could hang on to it.
Apparently we're not realizing just how short 80 attoseconds is. You doubt human hands could hang on to it? Moving 24mm in 80 attoseconds is faster than the speed of light. Not only is it faster than the speed of light, it's a million times faster than the speed of light.
Light only travels 24 nanometers in 80 attoseconds.
ZFS: because love is never having to say fsck
Or people who don't like to have their search results artificially curtailed by someone else's sense of unreasonable morality.
Check out the book QED: The Strange Theory of Light and Matter, by Richard Feynman. The answer is basically that the photon doesn't bounce off of anything! It "interacts" with an electron, and another photon is emitted. Why is it emitted at the particular angle? That's what the book is all about. Way too much to explain here. But if you want to understand in layman's terms how reflection and refraction work, and why glass is transparent, get that book, it's wonderful.