The ULTRAFAST project is based on the FRAME technique that, in short, is an imaging technique that allows the user to store several images in a single photograph (i.e. a film in a picture) using an image-coding approach. Exactly how many images a single photograph can hold depends on a variety of factors, such as the resolution of the sensor, the object under study, how the images are being coded. In the project we have investigated how these factors influence the obtained result and demonstrated the potential of achieving +1000 images within a single photograph. The number of images a sensor may hold simultaneously is an important factor since the amount of images the photograph holds sets the length of the extracted film, which needs to be long enough to cover the entire event - the more images the film contains, the more information and conclusions can be drawn from the film.
As described, ultrafast videography by means of FRAME requires ultrafast laser technology. However, FRAME videography can be performed using less complex light sources as well, which can facilitate the spread and usage of the technology. We have investigate the flexibility of FRAME and demonstrated how it can be combined with modern, state-of-the-art, yet inexpensive LED illumination technology to breach MHz frame rate videography, thus offering a cost-effective alternative to high-speed cameras.
The unique image-coding methodology with FRAME can be used for more than videography and we have also demonstrated the ability to store (1) spectral information into a single photograph for highly sensitive snapshot hyperspectral imaging and (2) three-dimensional data, demonstrated by, for the first time, visualising a plasma channel in 3D. Hyperspectral imaging is routinely used within both industry and science and we believe the versatility of image-coding using FRAME will open new technological avenues. Coded light can make inherently “colorblind” cameras, such as intensified cameras, spectrally sensitive, which also has been demonstrated within the ULTRAFAST project.
The world's fastest detector is called a streak camera, commonly used to study molecular dynamics occurring on a picosecond timescale. The technical solutions that make the streak camera fast do, however, yield certain issues such as image blur and loss of temporal contrast. In the ULTRAFAST project we have investigated whether these artifacts can be suppressed by simply applying a similar image-coding strategy as used in FRAME and have, thus far, been able to demonstrate experimentally an improved temporal contrast when combining the streak camera with FRAME-based image-coding.
Besides the above mentioned work, the two core research directions in the ULTRAFAST project have been the development and application of (i) interferometric ultrafast videography, and (ii) a novel diagnostic concept we refer to as coherence lifetime imaging (CLI), designed for visualizing ultrafast chemical processes. Interferometry, while highly sensitive, has previously been incompatible with ultrafast videography. By redefining FRAME’s analysis algorithms, we succeeded in extracting hidden interferometric signals, achieving high-fidelity imaging of nature’s fastest events.
Inspired by fluorescence lifetime imaging (FLI), CLI overcomes key FLI limitations. While FLI is restricted to fluorescent targets and nanosecond timescales, CLI probes spectral features from molecular rotation and vibration—about 100 times faster—thus accessing a new class of ultrafast chemical phenomena.
