title: Unwinding of the uniform lying helix structure in cholesteric liquid crystals next to a spatially uniform aligning surface.
abstract: The symmetry of the cholesteric uniform lying helix (ULH) structure, where the helix axis is aligned in a single direction parallel to the device substrates, is not compatible with a uniform surface alignment and an unwinding of the helical structure is expected at the interface. Fluorescence confocal polarizing microscopy experiments are performed on the interface between a bulk ULH and a uniform aligning surface (for both planar and homeotropic alignments). The results are analyzed in the framework of a finite difference numerical simulation based on the Frank elastic distortion, to determine relevant director structures. An optical model is introduced to predict three-dimensional fluorescence profiles for the structures. Comparison of experimental and theoretical results shows that the equilibrium structure of the system involves a continuous unwinding of the helix close to the surface.
authors.affiliation: Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Salter
authors.forename: Giovanni
authors.initials: G
authors.lastname: Carbone
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Jewell
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Elston
authors.forename: Peter
authors.initials: P
authors.lastname: Raynes