Corrugations on the free surface of nematic liquid crystal layers

In this paper we quantitatively treat an equilibrium problem for the free s urface of a monomeric or polymeric nematic liquid crystal layer, which has been suggested by some novel industrial applications. Think of a layer depo sited on a plane. rigid substrate, whose optical axis is anchored in such a way that the azimuthal angle is everywhere defined, whereas the polar angl e may freely vary. Let further the azimuthal anchoring be discontinuous alo ng a line on the substrate. To accommodate this singularity within a contin uous field, the optic axis must flip out of the substrate plane and become orthogonal to it at the anchoring discontinuity. Such a distortion entrains a corrugation on the free surface of the layer. Experimentally, the existe nce of corrugations at the alignment boundaries of nematic liquid crystal p olymer films on single glass substrates is demonstrated by photo-aligning a nd photo-patterning such films by the linear photopolymerization (LPP)-tech nology of ROLIC.