Single-Acquisition 2-D Multifocal Raman Spectroscopy Using Compressive Sensing.

Confocal Raman microscopy is a powerful method for nondestructive and noninvasive detection of chemicals with high spatial resolution, but its long acquisition time hinders its applications in large-scale monitoring of fast dynamics. Here, we report the development of a compressive sensing technique for single-acquisition multifocal Raman spectroscopy, which is capable of improving the speed of conventional confocal Raman spectroscopy by 2-3 orders of magnitude. A sample is excited with a 2-D multifocus pattern, and the Raman scatterings from the multiple foci were projected onto the spectrometer's entrance in a 2-D array. The superimposed spectra within each row of the array were processed with an algorithm such that the spectra from the individual foci were retrieved in a single acquisition and with reduced noise. The performances of the developed technique were demonstrated by parallel Raman spectroscopy of multiple individual particles as well as by single-acquisition confocal Raman imaging of a large scale with high spatial resolution when combined with spatially sparse sampling. The technique is expected to find wide applications in investigating fast dynamics in large-scale biological systems.