Thermo-Optic Effect of Smectic A Liquid Crystals in Hybrid Cells

Abstract

For cells having a hybrid boundary condition, the thermo-optic effect has been investigated during the cooling process from a nematic to a smectic A phase under the influence of an electric field. The texture and the transmission that occurs during the smectic A phase strongly depend on the bias voltage. To investigate the layer alignment in smectics, the capacitance of the cell is measured for various textures, and the relationship among textures, transmission, and capacitance is discussed. Also investigated is the phenomenon of textural relaxation near the smectic A to nematic phase transition temperature. It was found that the field-induced homeotropic texture relaxes to the preferred scattering texture through the nucleation of spherulites.

Key Words:

• smectic A liquid crystal
• thermo-optic effect
• textural change
• textural relaxation
• capacitance analysis