Optical characterization of chevron texture formation in nematic electroconvection

Abstract

We characterize the director structures in electroconvection patterns of nematic liquid crystals by means of polarising microscopy. This study was stimulated by a theory put forward by Rossberg et al. (patt-sol/9701005) who propose a mechanism for chevron texture formation. We characterize the relation between the wave vector modulation and in-plane twist modulations of the director field. In addition to the standard optical setup, a circular analyzer is used. The results provide new insight into the interplay of director and wave vector field leading to the chevron texture and fluctuating conductive rolls. Our experimental results confirm the theoretical predictions.