MIT researchers used a streak camera system to construct the world's fastest slow motion camera at 1 trillion frames per second. With it, the team slowed a light pulse down enough to distinctly see its propagation through a medium, a plastic bottle in this case.
A streak camera takes the temporal profile of a light pulse into a spatial profile on a detector. In other words, it applies a time-varying deflection of the light across the internal detector. Hamamatsu Streak Camera tutorial states, "Light pulse enters the instrument through a narrow slit along one direction. It gets then deflected in the perpendicular direction so that photons that arrive first hit the detector at a different position compared to photons that arrive later." (See the Hamamatsu website for a video demonstration.)
Mechanical streak cameras use mirrors to deflect the light as needed. Optoelectronic streak cameras turn photons into electrons via the photoelectric effect in a photocathode. Electric potential can then change the direction of the electrons between two charged plates after cathode-ray tube acceleration.
Media Lab Associate Professor Ramesh Raskar and Lester Wolfe Professor of Chemistry Moungi Bawendi performed the experiment multiple times to collect the final motion set. They would first take the streak image at one point. After incrementing to the next slice position, another set of images were collected. They would time the light pulse and camera accordingly to mimick having hundreds of streak cameras in a row. In the end, the video was stitched end to end, creating the final video above. That one light pulse in the film is actually a collection of hundreds. Raskar commented about the system, calling it "the world’s slowest, fastest camera.”
Between the laser and streak camera, the team paid out $250,000 USD to equipment provider Bawendi. A small price to pay to understand the way light moves.
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