Somewhere, Doc Is Smiling
To the annals of the unbelievably cool, add this: a camera that can image one trillion frames per second. That’s fast enough to make a movie of light in motion.
Let me say that again: this apparatus is sufficiently precise and capable of such extreme slow motion photography that it can make a moving images of light in transit:
My favorite part of the movie itself (as opposed to the ridiculously cool tech and the gorgeous underlying science) is the choice of target, amidst all that ferociously exact equipment. Yup. Coke does rule our world.
From the MIT press release linked above, here’s a basic explanation of what’s going on:
The system relies on a recent technology called a streak camera, deployed in a totally unexpected way. The aperture of the streak camera is a narrow slit. Particles of light — photons — enter the camera through the slit and pass through an electric field that deflects them in a direction perpendicular to the slit. Because the electric field is changing very rapidly, it deflects late-arriving photons more than it does early-arriving ones.
The image produced by the camera is thus two-dimensional, but only one of the dimensions — the one corresponding to the direction of the slit — is spatial. The other dimension, corresponding to the degree of deflection, is time. The image thus represents the time of arrival of photons passing through a one-dimensional slice of space…
…But it’s a serious drawback in a video camera. To produce their super-slow-mo videos, Velten, Media Lab Associate Professor Ramesh Raskar and Moungi Bawendi, the Lester Wolfe Professor of Chemistry, must perform the same experiment — such as passing a light pulse through a bottle — over and over, continually repositioning the streak camera to gradually build up a two-dimensional image. Synchronizing the camera and the laser that generates the pulse, so that the timing of every exposure is the same, requires a battery of sophisticated optical equipment and exquisite mechanical control. It takes only a nanosecond — a billionth of a second — for light to scatter through a bottle, but it takes about an hour to collect all the data necessary for the final video. For that reason, Raskar calls the new system “the world’s slowest fastest camera.”
And yup, somewhere, Doc Edgerton is one happy camper.
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