Dynamic Channelled Spectrum of Nematic Liquid Crystal

In this paper we analyse the optical properties of an anisotropic nematic liquid crystal with the channelled spectrum method. The nematic liquid crystal, oriented homeotropically, placed between two crossed polarizer’s and illuminated with a parallel beam of white light, is subjected to rectilinear oscillatory shear. The transmitted light by the sheared sample is projected on the slit of the spectroscope. A dynamic channelled spectrum is then observed. The number of the grooves of the dynamic channelled spectrum increases progressively according to the amplitude of shear. The channelled spectrum resulting from the interference between the ordinary and the extraordinary beams is analyzed to deduce the birefringence and the molecular orientation of the sheared nematic sample.