Uniform planar alignment

Note 2 Sometimes a uniform planar alignment is called a uniform homogeneous alignment . The latter term is not recommended. 

Molecular alignment for which the director rotates in a helical fashion when passing between two substrate surfaces having molecules in uniform planar alignments. 

Fukuda, K., Seki, T., Ichimura, K., and Komitov, L. Uniform planar alignment of nematics on photooriented linear polysilane. Mol. Cryst. Liq. Crys., 368, 535 (2001). 

The surface polarization can be measured by different means. The most straightforward one is based on the pyroelectric technique [15]. To measure P one has to deal only with one surface of a cell with uniform director alignment, either planar or homeotropic at both interfaces. The main idea is to use a spatially dependent temperature increment in order to separate the contributions to the pyroelectric response coming only from the surface under study and not from the opposite one. By definition, the pyroelectric coefficient is y = dPIdT where P is macroscopic polarization of a liquid crystal and T is temperature. If we are interested only in the polarization originated from the orientational order we can subtract the isotropic contribution to y and calculate P in the nematic or SmA phases by integrating the pyroelectric coefficient, starting from a certain temperature T, in the isotropic phase ... 

When a planar-aligned liquid crystal slab with a birefringence An and a uniform director is placed between crossed polarizers and the slab rotated between the polarizers, the total transmitted intensity varies as sin 20, where 6 is the angle between the polarization direction of the first polarizer and the direction. Starting with an incident wave with intensity /q, show that (a) the ordinary and extraordinary waves have a phase shift... 

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