A trillion frames per second

[CCIP]

This was featured on BBC earlier today, and honestly I found the footage to be mesmerizing:

A special camera imaging system built to produce images at a dizzying one trillion frames per second. That is so slow that light appears as pulses of photons traveling in a line. The video shows a laser pulse traveling through a coke bottle, which at this rate appear as a 'bullet' of light floating through the air.

That is really, really cool. Reminds me of how the speed of light is one of those things that's always hard to imagine - but here it is actually captured

[frau kaleun]

I'd say something clever but my head just asploded.

[Rockstar]

Neat, I came here just now ready to paste the same link but you beat me to it.


Here's another from MIT http://web.media.mit.edu/~raskar//trillionfps/



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[Sailor Steve]

Originally Posted by CCIP

A special camera imaging system built to produce images at a dizzying one trillion frames per second. That is so slow that light appears as pulses of photons traveling in a line. The video shows a laser pulse traveling through a coke bottle, which at this rate appear as a 'bullet' of light floating through the air.

I'm confused (which is nothing new). I thought from the description given that is was a pulse of photons travelling in a line, and this was the only way they could actually capture it. I also thought that they had to sample it several times to get it to work, and that this meant that it was effectively faked.

[CCIP]

Originally Posted by Sailor Steve

I also thought that they had to sample it several times to get it to work, and that this meant that it was effectively faked.

Basically, yeah. It's not a real 'live video' - it's a composite of several takes of the light only at millions of frames per second, with colors etc. taken from a regular static picture of the bottle. But that's still very impressive.

[Sailor Steve]

Originally Posted by CCIP

But that's still very impressive.

Oh yeah. There's no question that, however they're doing it, they're still capturing a picture of light in motion. I mildly mocked the use of the word "sampling", but I also realize that sampled music in the CD world is still real music, and that this is still real light.

[Reece]

Obviously the burst of light must be slower that the speed of light (including electrons) otherwise how could you have a camera that was taking frames faster!! Awesome what ever!

[Catfish]

Strange idea of product placement.


No, i think it's great but can't help of thinking that they staged what they wanted to see, if you look at the experimental setup ?

"We use an indirect 'stroboscopic' method that combines millions of repeated measurements by careful scanning in time and viewpoints"

If you think of light refraction, the frequency of light is indeed changed, so it moves slower in a way through e.g. glass. So there is "slower light". You can think of particle fronts instead of waves like p(ressure)-waves within other media like rock.

[Skybird]

It is not cheated, because they said what they did. But what they did is not a 1:1 observation of reality, but they helped the visual effect a little by technically setting up an observation method that added own effect to the event to illustrate what was happening in the bottle. So, the film is technically brilliant, but indeed more a trickfilm than a documentary film about a light pulse passing through the bottle. I would say almost all what is to be seen is more illustrative for the camera technology's immense capability than for the light travelling through the bottle.

At least that is how I get it.

[Penguin]

very remarkable footage, great find!

Originally Posted by Catfish

If you think of light refraction, the frequency of light is indeed changed, so it moves slower in a way through e.g. glass. So there is "slower light". You can think of particle fronts instead of waves like p(ressure)-waves within other media like rock.

Well the light source we have here is a laser, which emits light at a (nearly) constant frequency. The wavelength is influenced by the refractive index of the medium. The refraction of the glass changes the wavelength, not the frequency and by this the speed of the light in the glass. [c (speed of light) = f (frequency) * l (wavelength)]. After the light exits the glass, it goes back to the same wavelength it had before - of course under the assumption that the medium before and behind the glass are the same; in this case air.

[Catfish]

Hi Penguin,

i was just relating to Reece's

"Obviously the burst of light must be slower that the speed of light (including electrons) otherwise how could you have a camera that was taking frames faster!! "

Was just joking there IS "slower" light in e.g. a glass cube, or prism.
However in this experiment the light goes just through the bottom of the bottle, and "ends" in the plug.

I think you would not see it if the light was not trapped in the plastic bottle ? Towards the end you see the bottle is filled with water.

You wrote:
" The refraction of the glass changes the wavelength, not the frequency and by this the speed of the light in the glass. "

Err what ? The wavelength IS the frequency.

[Penguin]

Hi Catfish,

the wavelength is the length between two repeating points of a wave, measured in meters; the frequency is the number of repetitions of said wave per second, measured in Hertz. Tha'ts how we get to the speed (distance / time , m/s)
The wavelength is directly corresponding to the visible color of the light, basically higher wavelenthgs -> red, infrared, lower -> blue/violett/ultraviolet

My point was only to show that (with a laser) the frequency stays the same, only the wavelenth changes and leads to the "slower light" in a medium with a higher refraction grade.

Oh, and I didn't notice also that the bottle was filled with a liquid, so this could be also used as a helper to slow it down.

Grüße in den Norden,
Penguin

[Catfish]

Hello,

" .. My point was only to show that (with a laser) the frequency stays the same, only the wavelenth changes and leads to the "slower light" in a medium with a higher refraction grade. .."

Ah ok, yes. My god optics is a loong way behind, i see it all through a redshift, thanks

[Platapus]

Originally Posted by Sailor Steve

that this meant that it was effectively faked.

Not faked as there does not appear to be any intent to deceive.

The title of the video is misleading as it is not actually collecting at 1T FPS, it is assembling data, collected over many collections, that represents a frame rate of 1T after extensive processing.

I think it is more a synthetic representation than a fake.

[Jimbuna]

Originally Posted by Platapus

Not faked as there does not appear to be any intent to deceive.

The title of the video is misleading as it is not actually collecting at 1T FPS, it is assembling data, collected over many collections, that represents a frame rate of 1T after extensive processing.

I think it is more a synthetic representation than a fake.

Looks that way