Trillion-frame-per-second video
web.mit.edu
web.mit.edu
Could an admin please change the link to a primary source like this one: http://web.mit.edu/newsoffice/2011/trillion-fps-camera-1213....
Or even this one: http://www.nytimes.com/2011/12/13/science/speed-of-light-lin...
[Edit]
gmaslov's comment provides an even better link, although not as 'newsy': http://web.media.mit.edu/~raskar/trillionfps/
It uses a 5ns long pulsed laser "photon torpedos" at 30hz to illuminate the scene and then captures the at a much higher sampling rate where the MIT system just scans a line at a time. So, unlike the MIT one, it's a small, hand-hold-able, system that captures full motion. [2]
You get full scene 3D without the drawbacks of scanning.
They flew one of their cameras on the last Discovery Mission.
[1] http://asc3D.com
[2] http://www.youtube.com/watch?v=3L91F9o600E
http://video.google.com/videoplay?docid=-3656494784112768834
I had the chance to play with it a couple years ago - quite amazing.
The Google Tech Talk goes into a little bit of detail about how they capture a stack of frames (slices in Z) into a buffer right behind the sensor and then dump that out for each snapshot.
A normal video camera records a frame at a time, this one records a scanline-sized movie at a time. The raw data is noisy but the scene is static so they can sample the same line over many flashes.
After a few minutes of scanning they have a trillion fps video where you can see a wavefront propagate at the speed of light. Amazing.
http://www.youtube.com/watch?v=EtsXgODHMWk
> MIT researchers have created a new imaging system that can acquire visual data at a rate of one trillion exposures per second. That's fast enough to produce a slow-motion video of light traveling through objects.
I wonder if the in-room impulse response of an LED light source could be exploited for ultra-high-bandwidth data transmission through open air.
I'm skeptical because.. how would you see a photon? Unless photons themselves give off light as they travel, but that would mean photons emit photons...
This would be very close to watching the light pulse travel across the scene...except for that second effect: that the parts of the scene are different distances from the camera.
They can. It's a non-classical concequence of Quantum Electrodynamics. If you are interested in the cross-sections, check out Berestetskii et al., 1982.
I think they were using the word "virtual" to describe the array of camera sensors as one camera. It sounds like basically they had an array of sensors all snapping as fast as they could, but offset in time from each other by some amount, to achieve the effect of having 1 frame for every N fractions of a second. They also had to break down the scene into long strips and repeatedly use the sensors take the same picture on each strip and re-combine the strips later.
> I'm skeptical because.. how would you see a photon? Unless photons themselves give off light as they travel, but that would mean photons emit photons...
What you were seeing in the video were the photons entering the camera after having bounced off of the scene. It's kind of misleading that they're making it sound like you're seeing the photons as they're hitting the object in real time, When in fact, the photons had already hit the object and are bouncing back into the camera. But the resolution with which they're detecting the incoming photons conveys the "shape" of the waves bouncing and propagating off/around objects. That's my take on it at least.
It was misleading in the way the commentator said we can now watch the photons as they travel through space.
Space is full of photons from stars and galaxies. We only ever see the source of their current direction, which is why space is black, but we see the the bodies within it.
Regarding the "seeing a photon," it's just an analogy.
It may be the laser being refracted by the air, just like commercial green lasers are refracted by fog. I actually think is the only explanation.(And neutrinos, because seriously, neutrinos rock).
Also, I can see some interesting uses to this camera, beyond light studying...
It is. Seeing is interacting with photons, so you can't 'see' a photon that didn't just hit your camera. The process is similar to how I heard we can see speed of light in space, as light from exploding star propagates through a nebula and reflects back to us. I can't find a reference for that though, I heard it as a story from a physics professor.
> And neutrinos, because seriously, neutrinos rock
And magnets.
Imaging Systems Applications Paper "Picosecond Camera for Time-of-Flight Imaging": http://www.opticsinfobase.org/abstract.cfm?URI=IS-2011-IMB4
ACM paper "Slow art with a trillion frames per second camera": http://dl.acm.org/citation.cfm?doid=2037715.2037730
They're not directly observing the photons in motion, they're observing what parts of the scene they're scattering off at a given point.
Also, photons don't "move" in their own reference frame, in which the entire universe is a zero-dimensional point with no time; for everybody who has mass, they are moving. At the risk of being mass-o-centric, I think it's not that wrong to speak of their "motion". Some of my best friends have mass.
http://en.wikipedia.org/wiki/Spacetime#Light-like_interval
You might be thinking of the fact that no proper time elapses along such a path, which is true but not relevant from an observer's perspective.
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Now imagine this: instead of registering images, camera emits them in the reverse sequence, effectively making the surrounding environment send concentrated coherent impulses to the point where the laser initially was.
Pew-pew.
Don't misunderstand me, this is really impressive and potentially has some important applications...
...but, because the final product showing the plastic bottle is a series of similar scenes, the video seems more akin to a cell or stop motion animation rather than to what is typically considered high speed photography which captures a single event and expands time rather than compressing it. Ten seconds of traditional high speed film contains images captured in a fraction of a second. In this video, ten seconds was captured over the course of many minutes.
In other words, there is a significant degree of editorial decision making regarding the manner in which events are depicted - even if that decision making is now handled by software.
But cool nonetheless.
In particular, check out "Flash" example in the downloads section.
I am not doubting it,that they've made a superb machine, but which photons does the camera catch to see photons that travel parallel to that same camera?
Imagine that you are in super slow-mo mode for a second. You hold up your hand and shine a flashlight on it. Since everything is in super slow-mo, you can watch as the photons strike your hand first, and it lights up. The photons that don't strike your hand continue on towards the wall next to you, and then some time after your hand lit up, the wall lights up, with a shadow of your hand.
> you can watch as the photons strike your hand first, and it lights up. The photons that don't strike your hand continue on towards the wall next to
This analogy doesn't work. In order to watch, some photons have to enter our eyes, but they haven't got there yet, as they're just now interacting with our hand, etc. I.e until sufficient photons enter our eyes (sensors), there's nothing to watch.
This points to the fact that the technique is not imaging the whole scene at once, but doing some kind of reconstruction on an assumed static scene.
The actual imaging device is just a long line of photosensors. The camera aperture uses a varying electric field to deflect photons that arrive later to sensors further down the line, producing an image in effective 2D - 1D of space and 1D of time. By repeating the scene and slowly scanning the camera's mirror, a composite video is built that shows diffusion of a picosecond laser pulse.
blink
They're using photon-photon scattering? Wow. I thought in order to pull that off you needed very high powered lasers.
Edit: "But while both systems use ultrashort bursts of laser light"
Depending on how they define "ultrashort" this might be the key.
So a photo cathode generates electrons which are deflected.
http://www.advancedscientificconcepts.com/technology/applica...
While cool, it's not a true 1 trillion fps camera.
Here's true 1 million fps footage:
Sounds a lot like a CRT. Or some of the oldest video capturing techniques (scanning line by line into a photo diode, and then using that signal to vary light on the output following the same scanning pattern).
The only thing that this camera is missing from other high-speed cameras is 1000 more lines in parallel, and a faster cool-down between frames. And many high-speed cameras in the past got around the cool-down by using multiple cameras, each taking a different slice of the action, and stitching them back together afterwards, but they're still considered high-speed cameras.
This could be 100% identical if they built a million of them and took a video in one shot, but it isn't currently feasible or cost-effective. And, since their 'bullet' is non-destructive, there's no reason to not simply repeat it with a cheaper technique.
So, you could assume that the scene is static, but that's just not true in any scene.
Look up Debevec's Light-stage work on Digital Emily. One of the unanticipated benefits of fast, high-detail face capture is that we get to see how skin really deforms. This after decades of papers on how skin is supposed to deform.
This new camera has limitations of course, but it has a time resolution literally 1,000,000 times the one in your video.