Slow-motion video has already shown us so much about how bullets make fruit explode, how birds fly, and how lizards run on water. Now they can capture a streak of travelling light. A team from the MIT media lab has created a camera system that can capture a trillion-frames-per-second and visualise the speed of light.
To produce a video that captured moving photons, the scientists used a streak camera, which is normally used to measure light in intensity and duration (time). A streak camera, however, reduces a scene into a single-dimensional slit by deflecting protons with an electrical field. So the video is actually a combination of trillions of slit images.
All of the images were taken through a single lens connected to a box that contains 500 camera sensors. Each sensor was programmed to take an image at a trillionth-of-a-second delay. While the sensors were firing off, the scientists rotated two mirrors so that the entire scene made its way through the slit.
The scene itself is a pulse light source directed by mirrors into an empty soda bottle (seriously). The scientists used a titanium sapphire laser because it emits regular pulses of light, so all the exposures look about the same and can be stitched together into one extremely slow motion video. This is why the scientists call it "the world's slowest fastest camera."
As for real world practical uses of a "light-speed camera," the scientists say it could be used in medical imaging such as light-based ultrasound. In cases where the camera can't record repeatable events, it could be used to capture how light scatters against an object in order to analyse its physical structure. Another possibility could be future consumer cameras that can artificially create lighting effects made by umbrellas, softboxes, and other expensive studio lighting equipment.
(Photo courtesy of MIT)
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