Optical anisotropy in colloidal crystals

Abstract

We use the theory of dynamical diffraction to interpret polarization-dependent light attenuation phenomena in thin colloidal crystals. We measure light attenuation anisotropies, resulting from coherent and incoherent scattering from a suspension of monodisperse aqueous polystyrene microspheres, with rotary polarization modulating polarimetry. Measured anisotropies are in excellent agreement with dynamical diffraction predictions. These measurements provide a new means to quantify crystal orientation in thin cells. We relate anisotropy to crystal color observed between crossed polarizers and to crystal structure, volume fraction and orientation.