Coherent intensity fluctuation model for autocorrelation imaging spectroscopy with higher harmonic generating point scatterers-a comprehensive theoretical study

We present a general analytical model for the intensity fluctuation autocorrelation function for second and third harmonic generating point scatterers. Expressions are derived for a stationary laser beam and for scanning beam configurations for specific correlation methodologies. We discuss free translational diffusion in both three and two dimensions. At low particle concentrations, the expressions for fluorescence are retrieved, while at high particle concentrations a rescaling of the function parameters is required for a stationary illumination beam, provided that the phase shift per unit length of the beam equals zero.