The World’s Fastest UV Camera

The team of Jinyang Liang, a specialist in ultrafast imaging at the Institut national de la recherche scientifique (INRS), in colla­boration with an inter­national team of researchers, has developed the fastest camera in the world capable of recording photons in the ultraviolet range in real time. Compressed ultrafast photo­graphy (CUP) captures the entire process in real time and unparalleled resolution with just one click. The spatial and temporal information is first compressed into an image and then, using a recon­struction algorithm, it is converted into a video.

Illustration of a compact, one-box UV-CUP system. (Source: J. Liang)

Until now, this technique was limited to visible and near-infrared wavelengths, and thus to a specific category of physical events. “Many pheno­mena that occur on very short time scales also take place on a very small spatial scale. To see them, you need to sense shorter wavelengths. Doing this in the UV or even X-ray ranges is a remarkable step toward this goal,” says Jinyang Liang. To record in this new range of wavelengths and to develop the technique into a user-friendly product, researchers designed a compact UV-CUP system with Christian Yves Côté of Axis Photonique Inc. via an academia-industry colla­boration.

The new system features a patterned photocathode, which is used to simultaneously detect and encode black light. “Like a standard camera, our technology is passive. It does not produce light; it receives it. Therefore, our photocathode had to be sensitive to the photons emitted as UV light. This design makes our technique a stand-alone system that can be easily integrated into various experimental platforms,” says Jinyang Liang, who has been contributing to the development of CUP since his postdoctorate. Liang worked with François Légaré, also from INRS, to generate and take images of UV pulses at the Advanced Laser Light Source (ALLS) laboratory. “The outstanding research environment at the Énergie Matériaux Télécommunications Research Centre of INRS is very helpful. It is so much more efficient when all necessary design, manufacturing, and characterization capabilities are available in the same building.”

“Taking the picture is only the first half of the job,” says Jinyang Liang. “It also has to be reconstructed.” To do this, the researchers developed a new algorithm, more efficient than standard algorithms, via their colla­boration with Boston Uni­versity. Its strength comes from a division of tasks. “Rather than solve the recon­struction problem as a lump, the algorithm divides the recon­struction into smaller problems that it tackles indi­vidually,” explains Liang.

With the innovations in both hardware and software, UV-CUP has an imaging speed of 0.5 trillion frames per second. It produces videos with 1500 frames in large format. As a light-speed imager, UV-CUP sees flying UV photons in real time. “It always fasci­nates me when you can watch the fastest object in the universe in such great detail,” says Yingming Lai, a Master’s student at INRS and the first author of the article.

The device developed through this inter­national colla­boration will be sent to the research laboratory SOLEIL Synchro­tron in France to visualize physical phenomena. It could capture laser-plasma generation, a pheno­menon that is essential for deducing certain properties of materials, and UV fluores­cence, which is important in medical imaging to identify biomarkers linked to diseases. (Source: INRS)

Reference: Y. Lai et al.: Single‐Shot Ultraviolet Compressed Ultrafast Photography, Laser & Phot. Rev. 14, 2000122 (2020); DOI: 10.1002/lpor.202000122

Link: Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique INRS, Varennes, Canada

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