High contrast coherent anti-Stokes Raman scattering microscopy using tightly focused cylindrical vector beams

Abstract

We report on a unique annular aperture detection scheme in radially and linearly polarized coherent anti-Stokes Raman scattering (RP- and LP-CARS) microscopy to effectively remove the solvent background for high contrast vibrational imaging. Our finite-difference time-domain (FDTD) calculations show that the far-field CARS radiation from the scatterer with size comparable to the excitation wavelength is stronger than that from the solvent at large cone angles (from 45° to the maximum collection angle of the objective). The annular detection provides about one to two orders higher contrast for forward detected RP- and LP-CARS microscopy. © 2011 SPIE.