Epi-detected hybrid coherent Raman micro-spectroscopy

Abstract

We demonstrate efficient epi-detected coherent Raman micro-spectroscopy using a simple laser system based on a femtosecond mode-locked oscillator. In our experiment, the non-resonant background is eliminated by using a hybrid technique, which combines laser pulse shaping and timing with frequency-resolved detection, and is based on the different temporal behavior of parametric and nonparametric processes. We perform careful analysis to make sure the coherent Raman-resonant signal is generated in the backward direction, and not forward-generated and then back-scattered. This demonstration may have important implications for coherent Raman microscopy.

Evans blue dye-enhanced imaging of the brain microvessels using spectral focusing coherent anti-Stokes Raman scattering microscopy

“…In more detail, a linearly chirped and stretched (~1 ps) pump pulse generates a CARS signal only when overlapped in time with the Stokes pulse, offering spectral information according to the extent of the pump/probe time delay. As another approach to reduce the non-resonant background, researchers reported that if a tissue sample is detected in the epi-detection, non-resonant signals from tissue components as well as the solvent are almost completely eliminated [ 19 ]. Such epi-detection is possible when the sample is highly scattering.…”