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 Post subject: Slo-mo video of light beam
PostPosted: Tue Dec 13, 2011 5:59 pm 
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I saw this and had to share, very cool!

http://futureoftech.msnbc.msn.com/_news ... ough-space

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Tue Dec 13, 2011 7:23 pm 
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Wow that was cool. A trillion frames per second for one row of pixels, impressive.

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Tue Dec 13, 2011 10:17 pm 
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Metroid wrote:
Wow that was cool. A trillion frames per second for one row of pixels, impressive.
Indeed, and since light "only" travels at 300 million meters per second, that means you can watch the beam of light advance in steps of just 0.3mm per frame!

...and to make this thread *slightly* relevant to twistypuzzles, that's about the same resolution as 3D printing on Shapeways. Wow! :shock:

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Tue Dec 13, 2011 11:22 pm 
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Quote:
According to the researchers, it takes only a nanosecond — a billionth of a second — for light to scatter through a bottle, but it takes nearly an hour to collect enough data to stitch together a video


I found this to be the most impressive. It just puts the speed of light into perspective for those who are unfamiliar with its speed (which is probably very little on this forum :P )

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Wed Dec 14, 2011 1:42 am 
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I felt like the video took the speed of light out of perspective actually.

For example, we're watching a beam of light propagate and we're still thinking in terms of the everyday world that we're used to, not realizing that we are observing light with light. That is, although the beams looks as though it is frozen midway through the bottle, in reality we know it must be much past that point because the light has had time to propagate to our eyes (or the camera in this case) to see it.

Ignoring the fact that this is stitched together from many events and just pretending that it was one continuous take, the camera is farther away than the bottle is long which means the entire event that we see happened (started and ended) before the video capturing started.

Also, we don't know the real pulse length of the light. I assume it is actually much shorter than the teardrop looking thing that propagates through the bottle in the video. My reasoning is that because we are seeing the pulse seemingly frozen midway through the bottle, the light that we see was scattered to the camera and some of the scattered light must have taken a longer path and hasn't had time to reach the camera yet. The light that takes a longer path will look more spread-out / blurry than the light that took a direct path to the camera. That is why there is a tail-like effect of the beam as it moves. The light at the leftmost part is the light that is just now reaching the camera even though the wavefront of light has moved past that point.

Interesting video...

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Wed Dec 14, 2011 7:37 am 
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bmenrigh wrote:
although the beams looks as though it is frozen midway through the bottle, in reality we know it must be much past that point because the light has had time to propagate to our eyes (or the camera in this case) to see it ... the camera is farther away than the bottle is long which means the entire event that we see happened (started and ended) before the video capturing started.

Yes, we see the light only when it hits the eye (via the camera, internet and then your video screen) after scattering from the smoke in the bottle, by which time the main beam will have already passed through the bottle. We wouldn't even see the light if it wasn't for the smoke inside the bottle, otherwise it would pass straight through and would never be deflected into the camera (except where it hits the plastic on entry and exit). In fact we don't even see the light that passes through the bottle at all - we only see the portion of that light which is scattered from the main beam and therefore does not pass through the bottle.

bmenrigh wrote:
Also, we don't know the real pulse length of the light. I assume it is actually much shorter than the teardrop looking thing that propagates through the bottle in the video. My reasoning is that because we are seeing the pulse seemingly frozen midway through the bottle, the light that we see was scattered to the camera and some of the scattered light must have taken a longer path and hasn't had time to reach the camera yet. The light that takes a longer path will look more spread-out / blurry than the light that took a direct path to the camera. That is why there is a tail-like effect of the beam as it moves. The light at the leftmost part is the light that is just now reaching the camera even though the wavefront of light has moved past that point.

I don't agree entirely with this. Most of the streaky tail/teardrop effect comes from a natural decline (half life) in the intensity of light (i.e., decreasing density of photons leaving the laser) at the end of a laser pulse, as the population of photons bouncing back and forth in the laser "gradually" find their way out of the laser. Remember that the exit of a laser is only partially mirrored, so (for example) 50% of the photons will exit at first pass while the other 50% will bounce back inside the laser, then 50% of that remaining 50% (i.e., 25%) will exit slightly later at second pass, 12.5% at third pass, and so on. This explains the streaky tail.

In fact secondary scattering of light in the smoke will be very rare, which is why the width of the pulse still looks quite sharp. Otherwise if the streaky tail was primarily due to secondary scattering in the smoke, then the blurring of light across the width of the pulse would be as great as that seen along the tail (more like a fuzzy sphere/circle), but that is not what we see in the video.

Therefore, the video shows very well the real shape and length of the pulse.

Still, I think it's incredible that we can effectively watch the pulse of light travel in slow motion at such high resolution (0.3mm per frame!!!), even though the video is "stitched together" by repeating the measurement many times.

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 Post subject: Slow motion footage of light !!!
PostPosted: Wed Dec 14, 2011 6:17 pm 
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Did anyone else see this ?

It's a new 'camera' (not really a camera but extremely close, the video explains it well) which can shoot at 1 Trillion frames per second !!!!

You can also find a footage of the light beam travelling slowly inside a water filled bottle on the internet, ut I think this video of the light beam's progression on a table with an apple and a reference clinder or whatever is enough. I think it's truly breathtaking to see light in slow motion... It basically means anything is visible in slow motion in the universe now ! I hope it'll help new scientific discoveries in the LHC ho knows =)

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 Post subject: Re: Slow motion footage of light !!!
PostPosted: Wed Dec 14, 2011 6:31 pm 
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:shock: :shock: :shock: :shock: :shock:

That is all.

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 Post subject: Re: Slow motion footage of light !!!
PostPosted: Wed Dec 14, 2011 6:35 pm 
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Kelvin posted it Here
Still it’s amazing.


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 Post subject: Re: Slow motion footage of light !!!
PostPosted: Wed Dec 14, 2011 6:46 pm 
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Ohh stupid -.- I'm sorry, I must've skipped the line, I didn't see :/

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 Post subject: Re: Slow motion footage of light !!!
PostPosted: Wed Dec 14, 2011 9:07 pm 
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That is just the best thing ever. Period.

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 Post subject: Re: Slow motion footage of light !!!
PostPosted: Thu Jan 05, 2012 2:04 pm 
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RubixFreakGreg wrote:
It basically means anything is visible in slow motion in the universe now !
Not really. It means anything that we can purposely recreate and record over and over again can visible in slow motion.

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 Post subject: Re: Slo-mo video of light beam
PostPosted: Thu Jan 05, 2012 7:26 pm 
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At first I didn't think this was "really" real so I read. I was thinking how the heck can a camera break the laws of the universe?

Turns out they came up with a nifty solution. This technique works like this

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