The optical properties of twisted nematic liquid crystal structures with twist angles ⩽90 degrees

Abstract

Liquid-crystal twisted nematic structures can be made with twist angles other than the conventional 90 degrees . It is shown that theoretically the transmission of such a structure when placed between two polarizers aligned parallel and perpendicular to the respective surface molecular directors is given by T=(1+u2)-1 sin2( theta (1+u2)12/) where u= pi d Delta n/ theta lambda , and theta is the twist angle, d being the cell thickness, Delta n the refractive index anisotropy of the nematic material, and lambda the wavelength of the transmitted radiation. In the idealized case T is taken to be zero. The departures from this, predicted by the above expression, are due to the fact that plane-polarized light becomes elliptically polarized as it passes through the nematic structure. Experiments confirm the validity of the theoretical model.

Tunable and Memorable Optical Devices with One-Dimensional Photonic-Crystal/Liquid-Crystal Hybrid Structures

“…2 that the extent of buleshift for E7 is greater than that for CYLC43. This result can be explained by their Mauguin parameters (Gooch & Tarry, 1975) 2d n u,…”

“…Generally, the M-mode TN, abbreviated as MTN, combines the polarization-rotation effect as well as birefringence effect. A traditional TN is primarily characterized by its polarization-rotation effect, which is manifested when the multiplication of the mesogenic bulk thickness and the optical birefringence (i.e., optical anisotropy), dn, is larger than the Gooch-Tarry first minimum condition, namely, √ /   0.866, where  is the wavelength (Gooch & Tarry, 1975). If dn is smaller than that condition, then the polarization-rotation effect is incomplete.…”

Geometric phase ando-mode blueshift in a chiral anisotropic medium inside a Fabry-Pérot cavity

“…The condition was obtained for minimal TN cell transmittance [32]. In Gooch-Terry minima both resonator phase ρ and twisted anisotropy phase υ are multiples of π .…”

Liquid crystal cell for space-borne laser rangefinder to space mission applications

“…When polarized light of the wavelength l incidents nor− mally on a TN structure and the plane of polarization of this light is perpendicular to n at the entrance of a TN layer and the transmission axes of "ideal" analyzer is parallel to n at the exit surface, the coefficient of transmission T of TN can be given by [3][4][5][6] …”