This Camera Tracks Photons At A Trillion Frames Per Second
Researchers at the MIT Media Lab have developed an “imaging solution” that let’s you “visualize propagation of light at an effective rate of one trillion frames per second.” In other words, MIT researchers have developed a camera that captures at the speed of light.
The new technique, which they call femto-photography, involves shooting a laser pulse as a flash and recording the light at about 1 trillion FPS. The laser pulse lasts less than one trillionth of a second, and that coupled with a narrow field of view meas that what you’re about to see “is captured over several minutes by repeated and periodic sampling.”
Here’s a pretty technical explanation of the awesome light-into-a-coke-bottle video you just saw:
The new technique, which we call femto-photography, consists of femtosecond laser illumination, picosecond-accurate detectors and mathematical reconstruction techniques. Our light source is a Titanium Sapphire laser that emits pulses at regular intervals every ~13 nanoseconds. These pulses illuminate the scene, and also trigger our picosecond accurate streak tube which captures the light returned from the scene. The streak camera has a reasonable field of view in horizontal direction but very narrow (roughly equivalent to one scan line) in vertical dimension.
At every recording, we can only record a movie of this narrow field of view. In the movie, we record roughly 480 frames and each frame has a roughly 1.71 picosecond exposure time. Through a system of mirrors, we orient the view of the camera towards different parts of the object and capture a movie for each view. We maintain a fixed delay between the laser pulse and our movie starttime. Finally, our algorithm uses this captured data to compose a single movie of roughly 480 frames each with an effective exposure time of 1.71 picosconds.
What’s the use of such a technique? Medical imaging, for one. It could also serve a purpose in an industrial or scientific setting. The researchers hope that at some point in the near future, this type of camera can be available for the masses in what would be an amazing advancement in consumer photography.
Here’s a way to visualize just how fast the light is actually moving and just how amazing this really is (condensed from the NYT):
That “movie” you saw of the light traveling through that Coke bottle was created by recording around 500 frames in a billionth of a second. Like I mentioned before, a narrow field of view makes it so that this process must be repeated over and over to build a complete picture of the scene. If they tracked the flight of a bullet in this way, that movie wouldn’t last 2 minutes like the one above. It would last 3 years.
What do you think? Do you see your iPhone 10 being able to capture at the speed of light?
For a visual explanation of the technology, check out this video below: