Schlieren textures in smectic liquid crystals

Abstract

The details of well developed schlieren textures have been observed at smectic C and B modifications. In these textures whole numbered point singularities occur and inversion walls with strong similarities to nematic schlieren textures. It is shown that the occurrence of smectic schlieren textures is due to suppositions derived theoretically by Nehring and Saupe. These suppositions are: tilted structure and plane layers with the layers parallel to the supporting glass slides.In smectic B inversion walls occur which allow to conclude on variable tilt angles of the structure.