Three-dimensional imaging of dielectric patterns in electrohydrodynamic convection of a nematic liquid crystal.
The transition from surface to bulk normal dielectric rolls in a nematic liquid crystal is imaged by fluorescence confocal polarizing microscopy. The three-dimensional director structure and the liquid flow are scanned in both the layer plane and the transverse plane. Two systems of small-scale convective flow are formed, one at each electrode. Strong anchoring makes director oscillations difficult and charges accumulate by the Carr-Helfrich mechanism. The middle region is a structureless convection where the director oscillates with the frequency of the applied voltage. The small-scale flow eventually fills the cell from one electrode to the other as one system of thin and elongated rolls. The true dielectric mode is not a director pattern, rather a surface flow instability.
Gheorghiu
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Liquid Crystal Institute, Kent State University, Kent, Ohio 44242-0001, USA. ngheorghiu@brynmawr.edu
Smalyukh
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Lavrentovich
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Gleeson
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