New and highly efficient methods for microscopic analysis of dynamic phenomena in biology and physics has been made possible in recent years by the junction between innovations in non-linear optics and imaging. However, there needs to be a way to record images in real time at a very short temporal resolution—in a single exposure – to really harness the potential of these methods.
What has happened is, this new technology is so precise that it operates on a scale beyond our characterization capabilities. For instance, lasers used at INRS produce ultrashort pulses in the femtosecond range (10–15 s) that are far too short to visualize. As INRS professor and ultrafast imaging specialist Jinyang Liang say, even though some measurements are possible, nothing beats a clear image.
Measurements taken with ultrashort laser pulses must be repeated many times using current imaging techniques, which is appropriate for some types of inert samples, but impossible for other more fragile ones. For instance, laser-engraved glass can tolerate only a single laser pulse, leaving less than a picosecond to capture the results. In this sort of situation, the imaging technique must be able to capture the entire process in real time.
That is why he and his colleagues, led by Caltech’s Lihong Wang, decided to develop what they call T-CUP: the world’s fastest camera, capable of capturing ten trillion (1013) frames per second! This new camera literally makes it possible to freeze time in order to see phenomena—and even light!—in extremely slow motion.
They began by improving upon the concept of compressed ultrafast photography (CUP). Even though it captured an image at 100 billion frames per second, CUP still did not meet, the specifications required to integrate femtosecond lasers. So, the new T-CUP system was developed. It is based on a femtosecond streak camera that also incorporates a data acquisition type used in applications such as tomography.
Professor Lihong Wang, the Bren Professor of Medial Engineering and Electrical Engineering at Caltech and the Director of Caltech Optical Imaging Laboratory (COIL), said:
“We knew that by using only a femtosecond streak camera, the image quality would be limited. 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 what is called a Radon transformation to obtain high-quality images while recording ten trillion frames per second.”
The new and improved T-CUP sets the world record for real-time imaging speed. In so doing, it has proven itself capable of powering a new generation of microscopes for biomedical, materials science, and other applications. This camera makes it possible to analyze interactions between light and matter at an unparalleled temporal resolution.
The ultrafast camera broke new ground the very first time it was used 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.
Jinyang Liang, the leading author of this work, who was an engineer in COIL when the research was conducted, said:
“It’s an achievement in itself, but we already see possibilities for increasing the speed to up to one quadrillion (1015) frames per second!”
Those as-yet undetectable secrets of the interactions between light and matter will surely be uncovered, at least partly, with speeds like that!
