Abstract
Polarization-resolved coherent Raman scattering (polar-CRS) provides rich information on molecular orientational organization, with the strong advantages of being a label-free and chemically specific imaging method. Its implementation, however, strongly reduces the imaging acquisition rate, due to limits imposed by polarization tuning. Here we demonstrate fast-polar-CRS imaging based on combined electro-optic polarization and acousto-optic amplitude modulations, applicable to both stimulated Raman scattering and coherent anti-Stokes Raman scattering imaging. The proposed scheme adds polarization information without compromising the capacities of regular CRS intensity imaging; increases the speed of orientational imaging by two orders of magnitude as compared with previous approaches; and does not require post-processing analyses. We show that this method permits sub-second time-scale imaging of lipid order packing and local lipid membrane deformations in artificial lipid multilayers, but also in red blood cell ghosts, demonstrating its high sensitivity down to a single lipid bilayer membrane.
Highlights
Coherent Raman scattering (CRS) imaging has progressed considerably over the past decade, making coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) powerful tools to monitor the presence of specific molecules in cells and tissues [1,2,3,4] with real-time imaging capabilities [5,6]
CARS results from a nonlinear induced anti-Stokes radiation, which is enhanced at the resonance condition ωp − ωs Ωr [Fig. 1(a)], whereas SRS is quantified by the amount of energy transfer from the pump to the Stokes when both beams are in resonance with a molecular vibration frequency Ωr [4] [Fig. 1(b)]
Electro-optical modulation of polarization at a rate of a few kHz has been used in second-harmonic generation (SHG), the SHG modulation phase being detected by lock-in amplification in regions of oriented molecules [25], or in homodyne SHG by interference with a reference SHG beam [26]
Summary
Coherent Raman scattering (CRS) imaging has progressed considerably over the past decade, making coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) powerful tools to monitor the presence of specific molecules in cells and tissues [1,2,3,4] with real-time imaging capabilities [5,6]. Typical molecular order imaging is performed at the rate of minutes for sequential polarization tuning on images of 150 × 150 pixels [17,19,21,22], to tens of seconds in schemes using synchronization between line scanning and polarization rotation [20] This limits the current applicability to minute-scale processes, with the obvious inconvenience of sensitivity to sample motion and lack of dynamics information. Electro-optical modulation of polarization at a rate of a few kHz has been used in second-harmonic generation (SHG), the SHG modulation phase being detected by lock-in amplification in regions of oriented molecules [25], or in homodyne SHG by interference with a reference SHG beam [26] These schemes did not extract molecular order information. To SRS, this scheme is applicable to polarization-resolved CARS, with fast dynamics and high sensitivity down to single lipid bilayer in cells
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
