TED: Ramesh Raskar - Imaging at a trillion frames per second (2012) | Текст песни

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• TED: Ramesh Raskar
• Imaging at a trillion frames per second (2012)

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Doc Edgerton inspired us with awe and curiosity with this photo of a bullet piercing through an apple, and exposure just a millionth of a second. But now, 50 years later, we can go a million times faster and see the world not at a million, or a billion, but one trillion frames per second.

I present you a new type of photography, femto-photography, a new imaging technique so fast that it can create slow motion videos of light in motion. And with that, we can create cameras that can look around corners, beyond line of sight or see inside our body without an X-ray, and really challenge what we mean by a camera.

Now if I take a laser pointer and turn it on and off in one trillionth of a second -- which is several femtoseconds -- I'll create a packet of photons barely a millimeter wide, and that packet of photons, that bullet, will travel at the speed of light, and, again, a million times faster than an ordinary bullet. Now, if you take that bullet and take this packet of photons and fire into this bottle, how will those photons shatter into this bottle? How does light look in slow motion?

Now, the whole event -- (Applause) (Applause)

Now, remember, the whole event is effectively taking place in less than a nanosecond — that's how much time it takes for light to travel — but I'm slowing down in this video by a factor of 10 billion so you can see the light in motion.

But, Coca-Cola did not sponsor this research. (Laughter)

Now, there's a lot going on in this movie, so let me break this down and show you what's going on. So, the pulse enters the bottle, our bullet, with a packet of photons that start traveling through and that start scattering inside. Some of the light leaks, goes on the table, and you start seeing these ripples of waves. Many of the photons eventually reach the cap and then they explode in various directions. As you can see, there's a bubble of air, and it's bouncing around inside. Meanwhile, the ripples are traveling on the table, and because of the reflections at the top, you see at the back of the bottle, after several frames, the reflections are focused.

Now, if you take an ordinary bullet and let it go the same distance and slow down the video again by a factor of 10 billion, do you know how long you'll have to sit here to watch that movie? A day, a week? Actually, a whole year. It'll be a very boring movie — (Laughter) — of a slow, ordinary bullet in motion.

And what about some still-life photography?

You can watch the ripples again washing over the table, the tomato and the wall in the back. It's like throwing a stone in a pond of water.

I thought, this is how nature paints a photo, one femto frame at a time, but of course our eye sees an integral composite. But if you look at this tomato one more time, you will notice, as the light washes over the tomato, it continues to glow. It doesn't become dark. Why is that? Because the tomato is actually ripe, and the light is bouncing around inside the tomato, and it comes out after several trillionths of a second. So, in the future, when this femto-camera is in your camera phone, you might be able to go to a supermarket and check if the fruit is ripe without actually touching it.

So how did my team at MIT create this camera? Now, as photographers, you know, if you take a short exposure photo, you get very little light, but we're going to go a billion times faster than your shortest exposure, so you're going to get hardly any light. So, what we do is we send that bullet, those packet of photons, millions of times, and record again and again with very clever synchronization, and from the gigabytes of data, we computationally weave together to create those femto-videos I showed you.

And we can take all that raw data and treat it in very interesting ways. So, Superman can fly. Some other heroes can become invisible, but what about a new power for a future superhero: to see around corners? The idea is that we could shine some light