Determination of viscoelastic coefficients from the optical transmission of a planar liquid crystal cell with low-frequency modulated voltage

Abstract

The viscoelastic response of the nematic director field to low‐frequency modulations of the driving voltage was studied by means of optical transmission measurements. An external ac voltage above the critical field U c was weakly amplitude modulated with frequencies in the range of 1 to 100 Hz. The viscosity coefficients α1, γ1, γ2, and η b influence the time dependence of the director field. They were determined by fitting the phase and amplitude of theoretically calculated optical transmission curves to measured data.