New method of determination of the Fr eedericksz threshold based upon precise fluctuation measurement

Abstract : In this paper we report a new method for determining the critical threshold of the Fr eedericksz transition driven by an electric field. It is based on the measurement of the amplitude of the molecule fluctuations as a function of the voltage di erence applied to a planar nematic cell. The precise measurement of the director fluctuations of the liquid crystal is made possible by the use of a very precise and sensitive polarization interferometer. The great advantage of the method is that it does not depend on complex ts as it is usually done in literature.