Toroidal Configuration of a Cholesteric Liquid Crystal in Droplets with Homeotropic Anchoring

Orientational structures formed in cholesteric droplets with homeotropic surface anchoring have been studied by means of polarization optical microscopy and computer simulations. It has been found that, when the ratio of the size of droplets to the pitch of a cholesteric helix ranges from 1.4 to 2.9, an axisymmetric toroidal cholesteric structure is formed with a topological linear defect in the form of an equatorially located surface ring. The features of the toroidal structure in cholesteric droplets and their optical textures for various observation schemes are examined in detail.