New MIT video camera shoots a trillion frames per second


December 13, 2011

Media Lab postdoctoral associate Andreas Velten explains how the camera works

Media Lab postdoctoral associate Andreas Velten explains how the camera works

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We've been hearing about trillions in the news so much lately, it's easy to become desensitized to just what a colossal number that is. Recently, a team of researchers at MIT's Media Lab (ML) built an imaging system capable of making an exposure every picosecond - or one trillionth of a second. Just how fast is that? Why, a thousand times faster than a nanosecond, of course. Put another way, one picosecond is to one second as one second is to about 31,700 years. That's fast. So fast, in fact, this system can literally slow down light itself and it does so in a manner unlike any other camera.

High-speed photography pioneer Harold "Doc" Edgerton established his groundbreaking laboratory at MIT, so it seems fitting that such work continues there today. But aside from the high speed aspect, any similarity between Edgerton's famous bullet-through-the-apple shots and the Media Lab's project abruptly ends. Whereas Doc shot on film illuminated by powerful strobes, the new "picocam" employs a bright titanium-sapphire laser light source and captures images with an array of about 500 sensors sequentially triggered one trillionth of a second apart. In the words of ML postdoctoral associate Andreas Velten, one of the system's developers, "there's nothing in the universe that looks fast to this camera."

A key component in this complex imaging system is a re-purposed streak camera, an instrument originally designed for measuring temporal variation in the intensity of light pulses. On the ML rig, the streak camera's aperture consists of a narrow slit. Light particles or photons enter here and encounter a rapidly-changing electrical field that deflects them perpendicularly to the slit. This field variation causes later-arriving photons to deflect more than those that arrived earlier, so the 2D images created represent time in one dimension (the degree of deflection) and space in the other (defined by the direction of the slit).

Unfortunately, individual one-dimensional slices of space do not an image make. To get a fully recognizable video of an event, say, a light pulse traveling the length of a one-liter plastic bottle, the event must be precisely repeatable thousands of times. After each light pulse, a mirror supplying the image to the streak camera is repositioned slightly until, slice by slice, the entire subject is captured - an additive process reminiscent of 3D printing that incorporates a bevy of delicate instruments and requires about an hour to complete. The voluminous raw data is then crunched into viewable two-dimensional image sequences by special algorithms developed by other members of the team. A lengthy process overall, the irony of which isn't lost on ML Associate Professor Ramesh Raskar, who dubbed their system "the world's slowest fastest camera."

Obviously, the need for exact repeatability is a significant limitation for a video camera, but the potential discoveries about the picosecond properties of light alone will probably more than make up for that. At US$250,000 for the laser and camera alone, it's not a system likely to be available for home use any time soon, but this valuable new tool will hopefully begin unlocking more of light's hidden secrets... quick as a flash!

Source: MIT

Check out the video below to get the full scoop on how the system works:

About the Author
Randolph Jonsson A native San Franciscan, Randolph attended the U.S. Naval Academy at Annapolis, Maryland before finding his way to the film business. Eventually, he landed a job at George Lucas' Industrial Light + Magic, where he worked on many top-grossing films in both the camera and computer graphics departments. A proud member of MENSA, he's passionate about technology, optimal health, photography, marine biology, writing, world travel and the occasional, well-crafted gin and tonic! All articles by Randolph Jonsson

This could open up our minds to new phenomenon. I can\'t wait to find out what can be seen like this.

Carlos Grados

Hasn\'t got a thing on my Box Brownie Camera.

I mean for one thing you can\'t get an extension cord long enough to take it anywhere.

Mr Stiffy

Can\'t wait to upgrade from my 120Hz high-def flat-screen.

Sambath Pech

First - I don\'t doubt the that the camera does that - though I\'ve never used it - but from common sense - I think those images were edited - I mean if an apple gets a bullet like we have in the image -three things are supposed to happen in that image -but only one did correctly - The three things are -

1) - From the bullet entry point, the spot was not supposed to explode since the bullet passed in and not out.

2) - It don\'t matter how strong the apple holder was - the apples ought to have dislocated on impact of the bullet.

3) - The left explosion of the apple is correct - but the hole size looks small for that bullet size especially when it\'s an apple - If I\'m left to judge that - I\'d say that apple was supposed to burst completely on the impact of the bullet.

Now - the flying bottle - that too is weird to me - I mean if a bottle with liquid content not full to the top flies at a speed where it moves that straight - then the liquid content should be totally relaxed on the bottom - and the top of the bottle gets the space - And maybe if the shot was taken immediately the bottle was fired - then the liquid should relax to the top while the bottom whole fully keeps the space -

Someone should just tell me I\'m wrong please .::

Victor Dammie Dammie

@Victor, the image of the apple wasn\'t shot with that camera - it was an example of current high speed photography. Besides, I doubt whether anyone could be bothered to fake it - it\'s not hard to photograph.

Flying bottle? The bottle in the video is stationary and light is moving through it, so I\'m not sure what you mean.

This camera looks very cool to me. Photography at a photonic level has got to be going places...

Marcus Carr

@Marcus Carr - thanks - it's clear now .::

Victor Dammie.::

why does he keep saying that they can see a photon moving through space? that's obviously impossible. sure you can see a pulse of light moving through water, but why doesn't he say that. it doesn't make sense.

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