ABSTRACT
The Poincaré sphere representation, a geometrical method for solving problems involving the propagation of polarized light through birefringent and optically active media, is applied to several electrooptic liquid crystal problems. The emphasis is on the twisted nematic case, for which the quiescent state solution was given by Mauguin in 1911. The Poincaré construction shows that the normal modes for the undeformed twisted nematic layer are slightly ellipticity. polarized and suggests convenient experiments for measuring the ellipticity. For the field-activated state, a construction is indicated as an alternative to matrix-multiplication methods.
ABSTRACT
This paper describes a simple electrooptic effect that can be achieved by placing. a thin nematic liquid crystal layer between two glass prisms of appropriate refractive index. For a range of angles of incidence on the prism-liquid crystal interface, light is partially transmitted or totally reflected, depending upon the electric-field-controlled orientation of the optic axis in the nematic layer.
ABSTRACT
The diffraction of light by a sinusoidal perturbation of the optic axis in a nematic liquid crystal is discussed. This corresponds to experiments at the electrohydrodynamic instability thresholds. An interesting qualitative feature appears: The diffraction pattern exhibits a contribution at half of the expected spatial frequency, corresponding to nonorthogonal traversals of the thick phase grating.
