On the way of reconstruction of the liquid crystal surface anchoring potential

Abstract

We extend further the theoretical and experimental studies of the actual surface anchoring potential reconstruction by polarization microscope technique in a wedge-shaped cell with weak surface anchoring forces filled by a chiral nematic liquid crystal (in Grandjean-Cano Wedge) and present the material for the sake of the reader convenience with a short coherent survey of our previous results. To realize the theoretically predicted options of observation of large director deviation angles from the easy axes φ at a wedge surfaces (up to π/2) the experimental studies of director distribution in Grandjean-Cano zones were performed. A weak surface anchoring at one wedge surface was obtained by photo-alignment technique. A strong surface anchoring at the second wedge surface was obtained by rubbing. The measurements were performed using polarizing microscope. The experimentally found director distributions in Grandjean-Cano zones were compared with theoretical ones calculated for various model surface anchoring potentials. As a result of the present studies the ways to enlarge (compared to the previous studies) angular range of the actual surface anchoring potential restoration were proposed and it was found that the experimentally found surface potential is nicely fitted by a new model surface anchoring potential, the so called model D-potential WD(φ)~φ2.