Imaging theory of nonlinear Raman confocal microscopy

A novel nonlinear Raman confocal microscopy utilizing Raman induced Kerr effect spectroscopy (RIKES) is presented in this paper. The imaging theory of RIKES confocal microscopy with Gaussian beam is derived. The imaging properties of RIKES confocal microscopy and the impact of different beam waist widths of Gaussian beam on the lateral and axial resolution have been analyzed in detail. It is proved that RIKES confocal microscopy has high sensitivity and high resolution, besides capability to characterize inherent structural features, such as vibration mode, vibration orientation, and optically induced molecular reorientation etc. Therefore, nonlinear Raman confocal microscopy that is based on RIKES has potential to provide a novel characteristic imaging method comparable to the existing imaging techniques based on other nonlinear optical processes, such as two-photon fluorescence, second harmonic generation (SHG) and coherent anti-Stoke Raman scattering (CARS).