From left to right: Professor Jinyang Liang, Yingming Lai, Doctoral Student, Heide Ibrahim, Director of ALLS, Miguel Marquez, Postdoctoral Student and Co-author of the study, and Professor François Légaré in front of the SCARF system at INRS. (Image: INRS)

Achieving speed records is not just for athletes. Researchers can also achieve this kind of feat thanks to their discoveries. This is the case of professor at the National Institute of Scientific Research (INRS), Jinyang Liang, and his team, whose research results have just been published in Nature Communications.

The group, based at the INRS Energy Materials Telecommunications Center, has developed a new ultra-fast camera system that can capture up to 156.3 trillion images per second with astonishing precision. For the first time, single-exposure 2-D optical imaging of ultrafast demagnetization becomes possible. Called SCARF (for swept-coded aperture real-time femtophotography ), this unique device captures transient absorption in a semiconductor and ultra-rapid demagnetization of a metal alloy.

This new way of doing things will contribute to expanding knowledge in many fields of study which affect modern physics, biology and chemistry as much as materials science and engineering.

Professor Liang is recognized as a pioneer of ultrafast imaging on a planetary scale. Already, in 2018, he was at the head of a major breakthrough in the field, which set the table for the development of SCARF.

Indeed, until now, ultra-fast camera systems were mainly based on an approach involving several images captured sequentially one by one. With these methods, data is acquired through brief, repeated measurements multiple times, then placed end to end to generate a film that reproduces the observed movement.

“However, this approach can only be applied to inert samples or to phenomena that reproduce exactly over time. More fragile samples, those that do not reproduce repeatedly or have ultra-fast speeds cannot be observed with this method," said Professor Liang.

“For example, studying phenomena like femtosecond laser ablation, like shock wave interaction with living cells or like optical chaos, is not possible,” specifies the researcher.

However, the first tool developed by Professor Liang's team responded to this lack. Their compressed ultrafast photography system called T-CUP (compressed ultrafast photography) was based on a femtosecond scanning and continuous image camera to acquire ten trillion (1013) images per second. This was a stunning first step in real-time, single-pulse, ultrafast imaging.

On the other hand, certain challenges persisted.

“Many systems based on compressed high-speed photography face degraded data quality as well as reduced image depth. These limitations are attributable to the operating principle which requires simultaneous cutting of the scene and the coded aperture," said Miguel Marquez, Postdoctoral Fellow and Co-first Author of the study.

However, SCARF makes it possible to overcome these challenges. Its imaging modality allows ultrafast all-optical scanning of a static coded aperture while recording an ultrafast phenomenon. The result is full sequence coding up to 156.3 THz at each pixel of a camera based on a charge coupled device (CCD). These results can be obtained in a single exposure at adjustable frame rates and spatial scales in reflection and transmission modes.

A Range of Possibilities

Thus, with the help of SCARF, the observation of unique phenomena that are not repeatable, ultrafast or difficult to reproduce becomes possible, in particular the mechanics of shock waves in living cells or in matter. These advances can potentially be used to develop better pharmaceutical products and medical treatments as well as improve the mechanical properties of materials.

In addition, SCARF promises very interesting economic benefits. Already, two companies, Axis Photonique and Few-Cycle, are working in collaboration with Professor Liang's team to produce a marketable version of their discovery which, moreover, is the subject of a patent.

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