Influence of liquid crystal molecular stacking structure on in-plane, out-of-plane retardation switching

Abstract

An SSD (Smectic Single Domain) liquid crystal panel was investigated of its in-plane retardation switching behavior. Focused factor in terms of retardation switching behavior was azimuthal anchoring strength of an SSD panel. The empirical approach clarified that as long as azimuthal anchoring at the surface of the panel was strong enough to keep initial liquid crystal molecular alignment forming as a “quasi-Smectic A” like uniform molecular stacking, its retardation switching was completely in-plane only. A thicker panel gap of an SSD panel having not strong enough azimuthal anchoring strength throughout the panel gap provides some local twisted molecular stacking, resulting in mixing some limited out-of-plane retardation switching. These dynamic retardation switching measurements have been with relatively simple optical measurement set-ups. Using a crossed Nicols optical setting whose incident light to sample panels is linearly polarized light, light throughput behavior was observed. With using additional pair of quarter wave plates whose incident light is circularly polarized light, in-plane only retardation dynamics was measured. Although quantitative lift-up angle which causes out-of-plane retardation switching still requires further detail investigation, this series of research has clarified surface azimuthal anchoring significance on in-plane only retardation switching behavior, and such relatively simple optical measurement provides an overall molecular stacking configuration at an SSD-LC panel. The quantitative lift-up angle during the switching at an SSD-LC panel is even possible with precision light throughput amount measurement. This approach would possibly provide some local molecular twisted stacking detail at an SSD liquid crystal panel.