Structure of the Blue Phase of a Cholesteric Liquid Crystal

Abstract

Bragg diffraction of visible and near-ultraviolet light in the blue phase of a cholesteric liquid crystal have been observed. It is found that there are two distinct blue phases: One is stable from about 0.5\ifmmode^\circ\else\textdegree\fi{}C below the clearing point to about 0.2\ifmmode^\circ\else\textdegree\fi{}C below it and has either a body-centered-cubic or simple-cubic structure. A second, clearly distinct phase appears in the 0.2\ifmmode^\circ\else\textdegree\fi{}C range immediately below the clearing point. The nature of this phase is unclear at this time.