Simple method for measuring the azimuthal anchoring strength of nematic liquid crystals

We present a simple method for measuring the azimuthal anchoring strength and the angular gliding of nematic liquid crystals at the surface of solid substrates. The method only needs symmetrical samples. It uses the averaging of the interference oscillations when using white light, which allows one to measure the azimuthal deviation angle at the surface delta phi directly from the polarizers angles at the minimum of light. It is then easy to determine the azimuthal extrapolation length xi (phi) on varying the cell thickness, e.g., by means of wedge cells. As an example, we measure the azimuthal anchoring strength of 5CB onto self-assembled monolayers deposited onto polished indium-tin-oxide. (C) 2001 American Institute of Physics.