STATIC AND TRANSIENT ELECTRIC-FIELD EFFECT ON HOMEOTROPIC THIN NEMATIC LAYERS

The experiments give a way to determine two elastic constants K//1//1 and K//3//3 and one viscosity coefficient gamma //1 of a nematic liquid crystal. ac electric field stresses applied to a thin layer of nematic liquid crystal modify its cooperative molecular alignment. So, the electrically controlled rotation of molecules induces a variable birefringence as a function of applied voltage and time. The experimental results in relation with the static and dynamic behavior lead to the determination of these previously stated parameters. Temperature dependence of these parameters is given in the nematic range.