H. Schmiedel et al., DETERMINATION OF VISCOELASTIC COEFFICIENTS FROM THE OPTICAL-TRANSMISSION OF A PLANAR LIQUID-CRYSTAL CELL WITH LOW-FREQUENCY MODULATED VOLTAGE, Journal of applied physics, 74(10), 1993, pp. 6053-6057
The viscoelastic response of the nematic director field to low-frequen
cy modulations of the driving voltage was studied by means of optical
transmission measurements. An external ac voltage above the critical f
ield U(c) was weakly amplitude modulated with frequencies in the range
of 1 to 100 Hz. The viscosity coefficients alpha1, gamma1, gamma2, an
d eta(b) influence the time dependence of the director field. They wer
e determined by fitting the phase and amplitude of theoretically calcu
lated optical transmission curves to measured data.