Observation of Edge Dislocations in Smectic Liquid Crystals

Abstract
Isolated single-layer edge dislocations in smectic liquid crystals are observed by polarization microscopy. The modification of the smectic-A—smectic-C transition temperature by the strain field of the dislocations is used to make them visible. Observations of periodic arrays in thin samples, by various polarization-contrast mechanisms, and the measurement of the Burgers vector confirm the nature of the defects observed.