THE STATIC NEMATIC DIRECTOR FIELD AT ELECTRODE EDGES

We have investigated planar LC cells with striped electrodes and two t ypes of surface alignment of the director. Their optical properties ar e studied by means of polarizing microscopy, and a simple model is pre sented to determine the twist and tilt deformation of the director fie ld. The optical patterns are simulated by computing the transmission f unction of the cell with model director deformations using the 4 x 4 m atrix formalism. Depending on the director alignment at the surfaces, different types of inversion walls have been observed. They form struc tures of a characteristic geometry influencing the optical performance of LC devices. LC parameters may be calculated from the geometrical p atterns of the observed defects. Any further attempt to calculate the exact static two-dimensionally (2D) deformed director fields in struct ured NLC cells ought to be checked by its consistency with the experim ental effects reported here.