Scanning conoscopy measurement of the optical properties of chiral smectic liquid crystals

We report on a new scanning conoscopic method which, by rotating the sample and analyzing the ellipticity of transmitted light, provides an accurate tool to measure the temperature dependence of the two indices ne, no and of the optical activity for uniaxial liquid crystals. Their determination is useful to give informations about the tilt angle θ and the macroscopic helicity in the different phases and then on the structures of the liquid crystal phases. We tested the method with the reference compound (99% S, 1% R)MHPOBC.