MIT’s created a camera that can capture a trillion frames a second – the ultimate in slow motion, say its developers.
It’s fast enough to produce a slow-motion video of a burst of light traveling the length of a one-liter bottle, bouncing off the cap and reflecting back to the bottle’s bottom.
“There’s nothing in the universe that looks fast to this camera,” says Media Lab postdoc Andreas Velten, one of the system’s developers.
The system’s based on a streak camera, which has a narrow slit for an aperture. 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 early-arriving ones.
The image thus has only one spatial dimension — the one corresponding to the direction of the slit – but also represents the time of arrival.
To produce their super-slow-motion videos, the MIT team used the streak camera to build up a two-dimensional image of a light pulse being passed through a bottle by repeating the experiment multiple times, continually repositioning the camera.
Unfirtunately, this means it takes about an hour to collect all the data necessary for the final video; algorithms then stitch that raw data into a set of sequential two-dimensional images.
This means the camera can’t record events that aren’t preciselyrepeatable. Any practical applications will probably involve cases where the way in which light scatters is itself a source of useful information.
One example might be analysis of the physical structure of manufactured materials and biological tissues — “like ultrasound with light,” says associate professor Ramesh Raskar.
Raskar also sees a potential application in the development of better camera flashes.
“An ultimate dream is, how do you create studio-like lighting from a compact flash? How can I take a portable camera that has a tiny flash and create the illusion that I have all these umbrellas, and sport lights, and so on?” he says.
“With our ultrafast imaging, we can actually analyze how the photons are traveling through the world. And then we can recreate a new photo by creating the illusion that the photons started somewhere else.”
See the video, below.
