Coherent anti-Stokes Raman scattering microscopy using tightly focused radially polarized light.

We report a radially polarized coherent anti-Stokes Raman scattering (RP-CARS) microscopy for facilitating longitudinally oriented molecules detection. We observe that under tight focusing of radially polarized pump and Stokes light fields with a high-NA objective, RP-CARS radiation from molecules oriented along the longitudinal direction is approximately threefold stronger than that using linearly polarized CARS (LP-CARS) technique. The lateral resolution of RP-CARS imaging can be improved by about 10% compared to the LP-CARS imaging. We demonstrate this RP-CARS technique by imaging the sectioned cottonwood leaf vascular bundles.