Fast polarization imaging in coherent Raman scattering for the observation of lipid order dynamics in real-time

摘要

Polarization resolved coherent Raman scattering (polar-CRS) provides information on molecular orientationalorganization, with the strong advantages of being a label free and chemically specific imaging method. Polarizationtuning imposes however slow imaging acquisition rates. Here we demonstrate two strategies to fasten polarizationresolved CRS and reach real time capabilities. First, fast polar-CRS imaging is obtained by a combined electro-opticpolarization and acousto-optic amplitude modulations, applicable to both Stimulated Raman Scattering (SRS) andCoherent anti-Stokes Raman Scattering (CARS) point scanning imaging. The proposed scheme increases the speed oforientational imaging by two orders of magnitude as compared to polarization tuning approaches, and does not requirepost processing analyzes. Second, a combination of circular-based polarizations is used to directly filter the organizationcomponents of the probed samples, benefiting from symmetry matching properties between light and molecularassemblies. We demonstrate the potential of those methods for sub-second time scale imaging of lipid order packing andlocal lipid membrane deformations in artificial lipid multilayers, single cell ghosts, and myelin-rich tissues from spinalcords in live mice. Notably, these images permit to extract molecular scale signatures that bring for instance newinformation on the early stage of the development of neurodegenerative diseases.