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.

• Received 23 June 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.1393