Patterns in hybrid nematic liquid-crystal films: Topography and topology -art. no. 195507

Spontaneous pattern formation in hybrid nematic liquid-crystal films on gly cerol was studied with both polarized transmission and unpolarized monochro matic reflected light microscopy. These observations reveal that the patter ns that are found in 1 to 10-mum-thick films are due to a combination of fi lm. topography, gradients in film. thickness that act as an aligning field, and topology, connectivity requirements on the vector field. The patterns studied include cellular patterns, disclinations connected by 2 pi -walls, and 2 pi -walls that narrow to a point at the edge of the films.