J. Phys. III France
Volume 7, Numéro 12, December 1997
Page(s) 2459 - 2474
DOI: 10.1051/jp3:1997105
J. Phys. III France 7 (1997) 2459-2474

Optical Characterization of the Director Field in a Distorted Nematic Layer

Emmanuel Plaut, Alain Joets and Roland Ribotta

Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay Cedex, France

(Received 30 June 1997, accepted 22 August 1997)

We develop new optical methods using transmitted polarized light for the characterization of the out of plane component nz 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 nz distortion. In ordinary light, a new type of contrast due to the anisotropic light scattering is shown to give the map of nz2. We apply our methods to the study of the director distortions occuring in the thermal convection.

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