If you ever wanted to see what light looks like as it travels through air, you would need the femtosecond streak camera developed by California-based researchers. The fastest optical instrument in the world, it snaps a staggering 10 trillion frames per second.
Developed by researchers from the National Institute of Scientific Research (INRS) and the California Institute of Technology (CalTech), it offers the next best thing to stopping time to take a photo of stationary particles.
Given the name "T-CUP," the femtosecond streak camera debuted in October 2018. A video showed how it captured the behavior of photons in the light as the beam passed through a bottle that contained a diluted mix of milk and water. The milk was added to the mixture to increase the visibility of the particles of light.
The researchers began the demonstration by recording the passage of a beam of light at a rate of 100 billion frames per second (fps). Photons take about 2,000 picoseconds to cross the length of a typical water bottle, with a picosecond measuring one-trillionth of a full second. (Related: Beat itchy skin – by shining a light on it?)
New T-CUP camera combines 2 different camera types to take 1o trillion fps
Even seen through the femtosecond streak camera's blistering speed of 100 billion fps, light still moved a million times faster than a bullet. So the researchers increased the rate to 500 billion fps, which lasted 450 picoseconds in real-time and slowed the photons down to just 200,000 times the speed of a bullet.
For the final part of their video, the researchers demonstrated the 10 trillion fps speed of the T-CUP camera. They recorded the beam of light as it passed through several millimeters filled with diluted milk. The scene took up just 50 picoseconds.
The CalTech-INRS camera incorporated both compressed ultrafast photography (CUP) and femto-photography. The former technique provided the base performance of 100 billion fps.
To boost the performance of the CUP camera, the researchers added a femtosecond streak camera. An integral part of scanning instruments, streak cameras measure the changes in the intensity of a pulse of light throughout a given period.
In a streak camera, photons move through a narrow slit. The device converts them into electrons during their passage. The combination of two different devices increases the number of fps that they can take.
The world's fastest camera in real-time imaging speed
CalTech researcher Wang Lihong added that femtosecond streak cameras suffered from limited image quality. So they used a data acquisition system taken from tomographic imaging.
"We added another camera that acquires a static image,” Lihong said. “Combined with the image acquired by the femtosecond streak camera, we can use what is called a Radon transformation to obtain high-quality images while recording ten trillion frames per second.”
The current holder of the world record for fastest imaging speed in real-time, T-CUP allows researchers to study the interaction between light and matter at an incredibly small scale of time. The new camera made it possible to develop a new generation of microscopes for scanning extremely small samples at incredibly slow motion.
INRS researcher Jinyang Liang said that he and his colleagues planned to integrate future developments in streak camera technologies to T-Cup and its potential successors. They wanted cameras that will take high-quality images at higher speed.
“But we already see possibilities for increasing the speed to up to one quadrillion (10 to the 15) frames per second,” explained Liang in an interview. “Speeds like that are sure to offer insight into as-yet undetectable secrets of the interactions between light and matter.”
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