Azimuthal anchoring strength

By measuring the twist angle, the azimuthal anchoring strength can be obtained. This method is called the twist angle method (TAM) [15,16]. 

The angle a that gives the minimum transmittance is found by 

In the experiment, the analyzer is rotated to find the minimum transmittance and thus to determine a . (po is calculated from Equation (5.86). 

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In real SmC cells both Wf and W are finite. A finite azimuthal strength would create an additional surface torque trying to move the director from its angular positions at (p = 0 or

easy axis z, Fig.13.13. On the cone surface, the minimum anchoring energy W corresponds to director position at (p = 7t/2 and the minima of are at

anchoring energies with equal amplitudes W... 

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