CONTROL OF AN EASY-AXIS ON NEMATIC-POLYMER INTERFACE BY LIGHT ACTION TO NEMATIC BULK

An appearance of an easy orientation axis of a nematic liquid crystal on the isotropic aligning surface under the light absorption by in-bulk azo dye molecules is observed. It is shown that orientation of LC molecules in the irradiated region is close to the direction of the exciting beam polarization. Accompanying to aligning, the surface driven reorientation effect has been studied. A threshold as well as a nonthreshold reorientation of the director toward the light-induced easy axis were observed. The value of the light-induced anchoring energy depends on the exposure time and achieves 2.5x10(-3)erg/cm(2). The experimental data are explained within the framework of adsorption of phototransformed molecules from the LC bulk onto the aligning surface.