Bessel beam coherent anti-Stokes Raman scattering microscopy

We report about laser scanning coherent anti-Stokes Raman scattering (CARS) microscopy using a Bessel beam to enhance the lateral resolution. This study covers a numerical investigation that predicts an improvement in the lateral resolution by a factor of up to 1.33, while the axial depth of view increases up to a factor of 2 for an ideal Bessel beam serving as both a pump and a probe. Further, we present a simple experimental implementation of a Bessel-like beam by adding only two axicons and a telescope to a conventional CARS laser scanning microscopy setup. The predicted resolution improvement is demonstrated for well-scattering, structured polymer samples.