World-Fastest Camera

The trillion-frame-per-second compressed ultrafast photography system. (Source: INRS)

What happens when a new technology is so precise that it operates on a scale beyond our charac­terization capa­bilities? For example, the lasers used at INRS produce ultrashort pulses in the femto­second range that are far too short to visualize. Although some measure­ments are possible, nothing beats a clear image, says ultrafast imaging specialist Jinyang Liang. He and his col­leagues, led by Caltech’s Lihong Wang, have developed what they call T-CUP: the world’s fastest camera, capable of capturing ten trillion frames per second. This new camera literally makes it possible to freeze time to see pheno­mena in extremely slow motion.

In recent years, the junction between inno­vations in non-linear optics and imaging has opened the door for new and highly efficient methods for micro­scopic analysis of dynamic pheno­mena in biology and physics. But to harness the potential of these methods, there needs to be a way to record images in real time at a very short temporal reso­lution in a single exposure. Using current imaging techniques, measure­ments taken with ultrashort laser pulses must be repeated many times, which is appropriate for some types of inert samples, but impos­sible for other more fragile ones. For example, laser-engraved glass can tolerate only a single laser pulse, leaving less than a pico­second to capture the results. In such a case, the imaging technique must be able to capture the entire process in real time.

Compressed ultrafast photo­graphy (CUP) was a good starting point them. At 100 billion frames per second, this method approached, but did not meet, the specifications required to integrate femto­second lasers. To improve on the concept, the new T-CUP system was developed based on a femtosecond streak camera that also incor­porates a data acqui­sition type used in appli­cations such as tomo­graphy.

“We knew that by using only a femto­second streak camera, the image quality would be limited,” says Lihong Wang, the Bren Professor of Medial Engi­neering and Electrical Engineering at Caltech and the Director of Caltech Optical Imaging Labo­ratory (COIL). “So to improve this, we added another camera that acquires a static image. Combined with the image acquired by the femto­second streak camera, we can use a Radon trans­formation to obtain high-quality images while recording ten trillion frames per second.”

Setting the world record for real-time imaging speed, T-CUP can power a new generation of micro­scopes for biomedical, materials science, and other appli­cations. This camera represents a funda­mental shift, making it possible to analyze inter­actions between light and matter at an unparal­leled temporal reso­lution. The first time it was used, the ultra­fast camera broke new ground by capturing the temporal focusing of a single femto­second laser pulse in real time. This process was recorded in 25 frames taken at an interval of 400 femto­seconds and detailed the light pulse’s shape, intensity, and angle of incli­nation.

“It’s an achieve­ment in itself,” says Jinyang Liang, who was an engineer in COIL when the research was conducted, “but we already see possi­bilities for increasing the speed to up to one quadrillion frames per second!” Speeds like that are sure to offer insight into as-yet undetec­table secrets of the inter­actions between light and matter. (Source: INRS)

Reference: J. Liang et al.: Single-shot Real-time Femtosecond Imaging of Temporal Focusing, Light: Sci. & App. 7, 42 (2018); DOI: 10.1038/s41377-018-0044-7

Link: Laboratory of Applied Computational Imaging, Institut National de la Recherche Scientifique, Varennes, Canada

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