MIT camera so fast you can see light photons, around walls

A camera created by scientists at MIT can capture a trillion frames per second – so fast that it can track photons of light and map objects around corners.

The video below by technology journalist David Pogue shows a packet of photons moving through a bottle of water, at 600 million miles per hour. The video lasts twenty seconds. If a bullet were shot through the same bottle and filmed by the same camera, the video would last a year.

The camera works by shooting a laser into the bottle. But a laser isn’t a single thread; it’s more like a long line of little pulses, one after another. The mirror in the camera moves slightly hundreds of times, so that it captures many cross sections of the same object. So it will capture the very tip of the cap, then a tiny slice right next to it, all the way until it captures a slice at the bottom of the bottle.

Each time it’s capturing a different one of those little light pulses as it passes through the bottle. The camera then stitches together each of those different cross sections into one image. This works because each light pulse that comes through basically looks the same as any other.

The video also shows how the camera can capture light shining on an apple: you can see the light reflecting off the floor, hit the apple, hit the wall behind it and finally create a shadow.

The video also explains how this camera can figure out what objects look like around corners by measuring how quickly the reflected light particles return from around the corner, since their speed is constant. It’s similar to sonar that tracks changes in the reflected speed of sound waves to create an image.

This story was originally published September 25, 2015 at 1:38 PM with the headline "MIT camera so fast you can see light photons, around walls."