Optical Characterization of the Director Field in a Distorted Nematic Layer

(Received 30 June 1997, accepted 22 August 1997)

Abstract
We develop new optical methods using transmitted polarized light for the characterization of the out of plane component n_z of the director field in a weakly distorted planar nematic layer. In extraordinary light, we relate the angles of aperture of the caustic surface to the local amplitudes of the n_z distortion. In ordinary light, a new type of contrast due to the anisotropic light scattering is shown to give the map of n_z². We apply our methods to the study of the director distortions occuring in the thermal convection.