Simple method for accurate measurements of the cholesteric pitch using a 'stripe-wedge'' Grandjean-Cano cell

摘要

The classical method for measuring the inherent periodicity, or "pitch'', in the order parameter in a cholesteric liquid crystal implies using a wedge cell with well-defined boundary conditions. But the error can be large due to difficulties in controlling the wedge angle, a. A modified method is presented that significantly reduces the measurement error. A relief of indium tin oxide stripes on one of the plates shifts the disclination lines a distance proportional to both relief amplitude and to the wedge angle. With this "stripe-wedge Grandjean-Cano cell'' the pitch can be accurately determined without a priori knowing alpha.