Fully leaky guided wave determination of the polar anchoring energy of a homogeneously aligned nematic liquid crystal

Optical excitation of a series of fully leaky guided modes has been used to explore the director distortion of a homogeneously aligned nematic liquid crystal (Merck-BDH E7) under application of an ac electric field (1 kHz) normal to the cell wall. Homogeneous alignment is realized by rubbed polyimide films on glass plates with indium-tin-oxide coatings. By using continuum theory to model the director profile through the cell to fit the fully leaky guided mode reflectivity and transmissivity data, both with and without applied fields, the changes of surface tilt angle and its gradient can be obtained from which the polar anchoring coefficient, W-theta, is derived. At 26.8 degrees C we find that W-theta = 1.2 x 10(-4) Jm(-2). (C) 2000 American Institute of Physics. [S0021-8979(00)00306-6].