Director Distribution in Cano-Grandjean Wedge Influenced by Surface Anchoring

Abstract

Experimental and theoretical studies of the chiral liquid crystal (CLC) director distribution in a wedge shape cell with a weak surface anchoring as well in a planar layer with a gradient of the pitch are performed. The theory predicts that the director distribution in individual Cano-Grandjean zones as well in narrow walls dividing the zones are dependent on the strength and shape of the anchoring potential. The performed calculations for a wedge and a planar layer of variable thickness show that the experimentally distinguishable details of the director distribution in the wedge area between two consequent walls (Cano-Grandjean zone) allow one to obtain information on the shape of the surface anchoring potential and especially favorable for the measurements are several first individual Cano-Grandjean zones. The measurements of the director orientation at the wedge surface with weak surface anchoring versus the coordinate along wedge surface carried out by means of optical polarized transmission spectra were used to reconstruct the director distribution at this surface for the second Cano-Grandjean zone. The relevance of the obtained director distribution to the different model surface anchoring potentials is discussed.