Optimum configuration for polarization photon correlation spectroscopy

Polarization photon correlation spectroscopy exploits the fluctuations in different polarization components of scattered light to deduce information about the shape of the scattering particles, in addition to the size information available from conventional photon correlation spectroscopy (PCS). The experimental arrangement is similar to that used in PCS and requires that the particles are sufficiently numerous for the scattered coherent light to be in the Gaussian scattering regime, but sufficiently sparse for multiple-scattering effects to be neglected. The cross-correlation function of intensities scattered into separate polarization states depends on the input polarization state, the scattering angle, relative refractive index and particle shape, and this information can be used to recover the aspect ratio of the particles. Combinations of input and output polarization states are analysed for their sensitivity to photon noise and other experimental uncertainties and two optimal configurations are identified. The robustness of the technique in these configurations is demonstrated using experimental data.