Non-Uniform Distortions During Electric Field Induced Unwinding of a Cholesteric Liquid Crystal

Direct experimental evidence is reported for non-uniform distortions of a cholesteric array undergoing an electric field induced nematic transition. The effect is most pronounced when sample thickness is comparable to the pitch, when the helix axis is parallel to the walls, and when the electric field is applied perpendicular to the helix axis. Thicker samples display helix expansion as a uniform process as field is applied, in accord with theory, and similar to the experimentally observed thermal pitch distortions.