Wide-field coherent anti-Stokes Raman scattering microscopy

We suggest a variant of coherent anti-Stokes Raman scattering (CARS) microscopy, which is a nonlinear microscopy method that has recently proven very successful in functional imaging of living cells with vibrational contrast. Whereas existing CARS microscopy techniques involve confocal scanning, in our setup excitation and detection are performed in a wide-field (nonconfocal) geometry, similar to a combination of dark-field and epifluorescence microscopy. The use of a nanosecond laser system rather than the typically used pico- or femtosecond systems furthermore implies a high spectroscopic resolution for various Raman-active substances. We demonstrate the feasibility of the wide-field approach on test samples and discuss its prospects to become a complemental method to confocal scanning CARS microscopy.