A team of researchers at the Massachusetts Institute of Technology have created a novel imaging system that has the capability to make light look “slow”.
Media Lab postdoc Andreas Velten, left, and Associate Professor Ramesh Raskar with the experimental setup they used to produce slow-motion video of light scattering through a plastic bottle. Photo: M. Scott Brauer
They deployed streak camera technology to obtain video at one trillion exposures per second. Andreas Velten, Media Lab postdoc, stated that it was an outstanding slow motion product. The data acquired was sufficiently fast enough for production of a slow-motion video of light that travelled from the bottom of a bottle to the cap and back.
The streak camera has a narrow slit as its aperture, which allows light particles to enter. The photons are made to go through an electric field, which deflects the particles in a perpendicular direction. The photons that arrive late are deflected more. The streak camera image is a two-dimensional image with the dimension corresponding to the slit direction being spatial, and the other dimension that corresponds to the degree of deflection being time.
Visualizing video at the speed of light — one trillion frames per second
The streak camera has the capability to register only a single spatial dimension, which is a drawback for video cameras. The experiment has to be repeated for constructing a two-dimensional image. Advanced optical equipment and mechanical control devices are required to synchronize the pulse-generating laser and the camera. The light scatters through a bottle in a nanosecond, but it requires an hour for collecting the data, justifying the name – “the world’s slowest fastest camera.”
Events that are not exactly repeatable cannot be recorded by the imaging system, as the imaging system needs multiple passes for production of videos. The trillion-frame-per-second imaging system can lead to better flashes for cameras. A portable camera with a tiny flash that can simulate sports lights and umbrellas is a possibility. The imaging system can also help analyze the travel of photons.
Ramesh Raskar, Moungi Bawendi, Velten and other researchers at the Media Lab Camera Culture group developed algorithms for stitching the raw data into sequential two-dimensional images. Quantum dots researcher, Bawendi, provided the $250,000 streak camera and light pulse-generating laser. The trillion-frame-per-second imaging system was presented at the Siggraph and at the Optical Society's Computational Optical Sensing and Imaging conference. This system is a spinoff of a camera project for seeing around corners.
Professor of applied holography at Sweden’s Royal Institute of Technology, Nils Abramson, pioneered a light-in-flight holography technique, which had the capability to capture light wave images at 100 billion fps. This technique required coherent light, while the MIT method used ordinary light, which allows viewing of photons. The trillion-frame-per-second imaging system can help in materials research and medical imaging.