Vibrational dephasing time imaging by time-resolved broadband coherent anti-Stokes Raman scattering microscopy

Time delay control in broadband coherent anti-Stokes Raman scattering (CARS) allows acquisition of time-resolved CARS images free of nonresonant background (NRB). We demonstrate that, in some cases, CARS image contrast is not chemical contrast but simply due to differences in NRB. Time-resolved CARS is used to rectify this by eliminating the NRB. We also construct a vibrational dephasing time image from a sequence of time-resolved CARS images of polystyrene beads in toluene. In doing so, we demonstrate the potential of imaging local molecular interactions between molecules and their surrounding in a structured medium.