When Time Freezes

The cameras we use in everyday life, especially the smartphone cameras, are quite slow. An average movie camera captures footage at 25 frames per second (fps). But there are also ultrafast cameras which can capture frames by the trillion.

A light-capturing camera from MIT, which has been around since 2001, can shoot one trillion frames per second. Of course, it is too fast for the human eye to register as we stop at about 1,000 fps.

Now a group of researchers from INRS (under the University of Quebec) and California Institute of Technology have made a further breakthrough and developed the world's fastest camera that can shoot 10 trillion (1013) frames a second. That massive frame rate means any dynamic phenomenon, even an ultrashort pulse of light, can be captured in extremely slow motion. As a result, time seems to 'freeze' and every minute detail can be watched which would not have been possible otherwise.

In a paper published in Light: Science and Applications, the researchers have described the tricky physics and mathematics behind the concept. Simply put, the new camera called T-CUP is a huge improvement on the existing imaging technique known as compressed ultrafast photography or CUP. Although CUP can capture 100 billion frames per second, its performance falls short when it comes to recording a dynamic phenomenon at a very short temporal resolution (the time it takes to capture a single frame), in a single exposure.

As of now, measurements taken with ultrashort laser pulses have to be repeated several times to obtain that kind of results, and it may not be too accurate in case of fragile samples. In contrast, the T-CUP provides single-shot, femtosecond (10-15 second) imaging in real time and the frame intervals could be as low as 100 femtoseconds in a single exposure.

According to the research team, the first time it was used, T-CUP managed to capture the temporal focussing (a time-related image focussing concept) of a single femtosecond laser pulse and detailed its shape, intensity and angle of inclination. The team has also put together a femtosecond streak camera and a camera for obtaining static images to improve image quality. Their next target is to increase the speed to up to one quadrillion (1015) frames per second.

The researchers say that the new camera represents a fundamental shift, making it possible to analyse interactions between light and matter at an unparalleled temporal resolution. It will also help create a new generation of microscopes and other equipment required for biomedical, materials science and other applications.