Real-time monitoring of the uniformity of planar textures and pitches of cholesteric liquid crystals

Two methods are proposed to evaluate the uniformity of planar textures (UoPT) and the uniformity of pitches (UoP) of cholesteric liquid crystals (CLCs). First, the real-time monitoring of UoPT and UoP of an area in CLCs is feasible by measuring the degree of linear polarisation (DoLP) of the output linearly polarised lights passing through the same CLC area. Second, the UoPT and the UoP can be evaluated by directly observing the uniformity of the transmission colour across the entire CLC sample sandwiched between two polarisers. The method that uses liquid crystals (LCs) (Δε < 0) to distinguish low DoLP values caused by non-UoPT or non-UoP in chiral azobenzene-doped LCs is also proposed.