SPATIALLY-RESOLVED STUDY OF THE FREEDERICKSZ TRANSITION IN THIN NEMATIC CELLS

We present a novel method for spatially resolved measurements of the a mplitudes of thermal fluctuations and surface pretilt angles in thin c ells filled with nematic liquid crystals (LC). We use the idea that th e dynamical response of the director field during a switching process critically depends on the initial conditions of the director field whi ch vary over the cell plane. The applied switching voltage acts as an amplifier which augments initial director deformations by orders of ma gnitude. By means of a CCD line scan camera combined with a polarizing microscope, we study the time dependence of the optical transmission curves. Their slopes give information on viscoelastic parameters where as their delay can be related directly to the initial director angle.