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The Slowest Slo-Mo Ever Recorded

Posted August 19, 2012 1:40 PM

From mental_floss:

"How does light look in slow motion?" asks Ramesh Raskar in this brief TED Talk, demonstrating his "femto-photography," a slow motion technique that achieves one trillion frames per second. He proceeds to show us: the camera captures so many frames that you can SEE LIGHT TRAVELING THROUGH WATER. You can see light moving across the surface of a tomato.

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#1

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 6:44 PM

This is definitely worth a look/see. Five stars!

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#2

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 7:27 PM

Like to try that with a higher energy wavelength...

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#3

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 8:52 PM

Great pun at the end: "It's a about time."

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#5
In reply to #3

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 9:29 PM

And an excellent presentation overall. I'm very interested in that camera. The bloke said the whole thing was Open Source for DIYers and so forth, though I doubt that a home-brew version will be featured in Make anytime soon lol.

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#6
In reply to #5

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 10:01 PM

Just another 555 timer project?

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#7
In reply to #6

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 10:03 PM

Not just another 555 timer project: one which actually uses the CV input on Pin 5.

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#4

Re: The Slowest Slo-Mo Ever Recorded

08/19/2012 9:05 PM

Another 5 *****

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#8

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 12:55 AM

The list of applications for this sampling and image building technique were pleasantly planted in reality. Nice to see folk being practical with their paradigm changing developments.

I could see the military taking a keen interest in this. Once they turn it into a tool it won't be long before it's available to the rest of us. Bring it on!

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#9
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Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 1:08 AM

"I could see the military taking a keen interest in this. Once they turn it into a tool it won't be long before it's available to the rest of us."

Given recent developments, I would change the phrasing ever so slightly to read,

"The government will take a keen interest in this. Once they turn it into a tool it won't be long before it's turned on the rest of us."

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#10

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 1:40 AM

As i understand it, thisonly works on completely static objects or completely repeatable occurrence. The entire slow mo video was built up from million of picture frame by frame over a long time. The entire motion is not real time. Real time slow mo is totally different. This is nonetheless, amazingly impressive!

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#11
In reply to #10

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 2:09 AM

There is no such thing as real-time slo-mo. Duh.

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#12
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Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 2:33 AM

You haven't seen me before the morning's coffee - or CR4's responsiveness this evening.

Did their server fall into a vat of cold molasses or what?

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#13
In reply to #12

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 2:58 AM

Yeah, out of the morning's frying pan and into the fire.

(Oops, wrong metaphor.)

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#14
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Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 3:28 AM

You getting that too?

Are you located near me?

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#15
In reply to #14

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 3:43 AM

Having the the same problem all night here out in the middle of North Dakota so I dont think its just your area.

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#17
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Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 4:53 AM

Minot is so far from everything that you weren't supposed to see these problems until tomorrow.

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#20
In reply to #15

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 6:49 AM

I am so far out in the sticks that you have to ride a pregnant mare to the mail box so that you will have something to ride back, so slow downloads are normal.

Even sunlight has a hard time finding this place.Doesn't get here till about noon elsewhere.

One thing I've learned is patience.Relax.

Sip Scotch..rock in chair...relax...sip Scotch...rock,repeat.

If it really matters, it will come.If not, back to R+R........

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#16
In reply to #11

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 4:42 AM

There is. It means the whole event is captured real time at very high frame rate at the very instant when the event occur, i.e. "one shot"

In the case of this camera, the full motion is made up of different frames captured from millions of repeated shots of event which were created exactly the same but repeated .

The amazing thing about this experiment is in the synchronisation of firing of the light "bullet", different frames from differrent event and compositing them together correctly to make it look like 1 event .

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#18
In reply to #16

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 5:21 AM

I doubt if they're doing it as you suggest, for several reasons: 1) they could not truthfully state the frame rate claimed, 2) they would be swamped with timing jitter if they were using repeated shots. In order to repeat those shots as you suggest would require sub-picosecond, possibly attosecond-level control over the timing jitter in order to produce the smooth motion seen in the video and 3) variations in laser output would require comparably fine control, else the image of the pulse would flicker noticeably. The pulse you see in the video is a single pulse.

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#22
In reply to #18

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 9:44 AM

I think not. That is, no brightness pulsing.

The experiment is repeated a large number of times with the same exposure delay so as to get a stacking or layering effect.

Astrophotographers use the same technique of multiple exposures of the same scene to magnify the light intensity.

In this case they precisely time the moment of exposure relative to the firing of the laser. Then repeat the sequence at the same time interval again and again until enough photons have been captured for correct exposure.

Then the process is repeated again with a slightly longer delay interval between laser firing and exposure each time, capturing multiple exposure for the next frame.

The reason you do not see pulsing is that each frame is an aggregate of many, many exposures, which accumulate to the same luminosity from the previous frame.

Dithering in time will not produce variation in brightness, but slight variation in position of the light packet. The net result is a somewhat fuzzy light wave packet of consistent intensity.

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#19

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 6:11 AM

OK, I'm impressed!

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#21

Re: The Slowest Slo-Mo Ever Recorded

08/20/2012 8:53 AM

Excellent.
Del

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