Video With 1 Trillion Frames Per Second Makes Light Look Slow

In photography, a shutter speed of one eight-thousandth of a second — the quickest setting on Canon's new EOS 1D-X pro digital SLR camera — is considered extremely fast. Some enterprising researchers at MIT just assembled a video that blows that spec out of the water by a factor of about 100 million.

Scientists at MIT's MediaLab have developed a video technique that results in videos made from 1 trillion frames per second — fast enough to show a light pulse moving across a room. Nothing moves faster than light, so the ability to reduce its progress to a slow-motion video is nothing short of miraculous. The team recorded a light pulse's progress through the length of a Coke bottle.

The camera uses a piece of equipment known as a streak camera, which is basically a slit that lets light pass through. The camera then uses a rapidly changing electrical field to deflect the light, measuring not just the photons coming through the slit, but also when they arrived. The result is a plot of light coming through that slit over time.

To create a picture that's more than just a slit, they had to record the "video" again and again, reflecting the light off mirrors and changing the angle every time so they would get a different part of the picture. Although the light takes an infinitesimal amount of time to move through the bottle, it took the researchers over an hour to get the material they needed — hundreds of thousands of data sets, amounting to about a trillion recorded "frames." They then crunch those numbers to manageable rates to produce the video seen above.

The methodology shows the main limitation of the system: It can only be used for recording something you can "shoot" over and over.

So what good is trillion-frame-per-second video capture? Media Lab Associate Professor Ramesh Raskar suggests medical imaging that currently uses ultrasound to scan inside a person could use light instead, presumably leading to more precising imaging (think picture-perfect sonograms of unborn children).

Another application could be better simulating studio lighting with a standalone camera flash. With a better understanding of how light progresses through a scene, a sophisticated flash could make pics from cellphone cameras look like they were taken by professionals.

Image: Di Wu and Andreas Velten, MIT Media Lab

[via MIT News]