Ultrafast laser spectroscopy allows the determination of dynamics over very short periods of time, making it an extremely useful tool for many scientific and industrial applications. The biggest drawback is the significant measurement time this technique typically requires, which often results in long acquisition times ranging from minutes to hours. Researchers have developed a technique to speed up spectroscopic analysis. The results of a project led by Hanieh Fattahi, research group leader at the Max-Planck-Institute of the Science of Light, in collaboration with industrial partners in Germany and France, were recently published. High-speed scientific journals.
Ultrashort pulses play an important role in spectroscopy applications. Wide spectral bandwidth allows simultaneous characterization of samples at multiple frequencies, eliminating the need for repeated measurements or laser tuning. Moreover, extreme temporal constraints allow for temporal isolation of the sample's response from the main excitation pulse. This response, which conveys comprehensive spectral information, takes place from tens of femtoseconds to nanoseconds (10-15 up to 10-9 seconds) are typically probed with shorter pulses at varying time delays. When integrated with other techniques such as multidimensional coherent spectroscopy or hyperspectral imaging, ultrafast spectroscopy facilitates the identification of unknown components. However, the goal of real-time measurements faces obstacles, primarily due to the extensive data recording required across the high-bandwidth spectrum of each pixel, resulting in significant delays in data capture, extended processing times, and increased data volume.
Researchers have developed a technique to speed up spectroscopic analysis. PhD student Kilian Scheffter, working with Hanieh Fattahi, head of the “Femtosecond point-of-care endoscopy” group at MPL, explains: “The response of molecules to ultrashort excitation pulses is typically sparse in many samples, at a frequency known as the molecular fingerprint. By strategically randomizing the measurement points, an established approach called compressive sensing allows the response of molecules to be less than the limit determined by the Nyquist criterion. The data points can be used to efficiently reconstruct the signal, and in collaboration with partners in Germany and France, we have successfully used acoustic waves to randomly modulate this temporal overlap. extended the application of compressive sensing to real-time spectroscopic measurements.”
“Accelerating time-domain spectroscopy offers several advantages, including simplified label-free imaging of fragile specimens, real-time environmental monitoring, field diagnostics of toxic and hazardous gases, and molecular in situ endoscopy,” says Dr. Hanieh Fattahi.