Physics

Spectral imaging

Microsecond

Laser

Optics

Astronomy

Ranging

Spectral resolution

Artificial intelligence

Ultrashort pulse

Materials science

Fingerprint (computing)

Computer science

Spectral line

Telecommunications

arXiv (Cornell University)

Label-free vibrational imaging by stimulated Raman scattering (SRS) providesunprecedented insight into real-time chemical distributions in living systems.Specifically, SRS in the fingerprint region can resolve multiple chemicals in acomplex bio-environment using specific and well-separated Raman signatures.Yet, fingerprint SRS imaging with microsecond spectral acquisition has not beenachieved due to the small fingerprint Raman cross-sections and the lack ofultrafast acquisition scheme with high spectral resolution and high fidelity.Here, we report a fingerprint spectroscopic SRS platform that acquires adistortion-free SRS spectrum with 10 cm-1 spectral resolution in 20microseconds using a lab-built ultrafast delay-line tuning system. Meanwhile,we significantly improve the signal-to-noise ratio by employing aspatial-spectral residual learning network, reaching comparable quality toimages taken with two orders of magnitude longer pixel dwell times.Collectively, our system achieves reliable fingerprint spectroscopic SRS withmicrosecond spectral acquisition speed, enabling imaging and tracking ofmultiple biomolecules in samples ranging from a live single microbe to a tissueslice, which was not previously possible with SRS imaging in the highlycongested carbon-hydrogen region. To show the broad utility of the approach, wehave demonstrated high-speed compositional imaging of lipid metabolism inliving pancreatic cancer Mia PaCa-2 cells. We then performed high-resolutionmapping of cholesterol, fatty acid, and protein in the mouse whole brain.Finally, we mapped the production of two biofuels in microbial samples byharnessing the superior spectral and temporal resolutions of our system.

Fingerprint Spectroscopic SRS Imaging of Single Living Cells and Whole Brain by Ultrafast Tuning and Spatial-Spectral Learning