Light Scattering Characteristics in Nematic-Cholesteric Mixtures with Positive Dielectric Anisotropy

The angular dependence of light scattering in nematic-cholesteric mixtures with positive dielectric anisotropy was measured; the quiescent transparent satate S , the focal-conic state F , the storage focal-conic state F 0 , and the field-induced nematic state H were investigated. The F 0 state showed Bragg scattering peaks caused by the lattice spacing of P 0 /2 where P 0 was the helical pitch of the mixture used. While, the light scattering profile for the F state under an applied electric voltage was found to be characterized by scattering peaks caused by the optical lattice spacing of P 0 itself, though the detailed physical reason has not yet been fully understood. The contrast ratio of the light scattering between F 0 and S was also discussed in connection with application to storage-type liquid crystal displays.