Surface polarization and flexoelectricity in nematic liquid crystals

We propose a technique for the measurement of the surface electric polariza tion in nematic liquid crystals from the birefringence variations of the te xture under weak vertical electric field. We study experimentally 5CB align ed on SiO layer with strong tilted anchoring. We show that in this system t he surface polarization is one order of magnitude stronger than the bulk fl exoelectric polarization of 5CB reported before. We discuss the sign and th e magnitude of the surface polarization and the reliability of the proposed method.