1 February 1998 Determination of azimuthal anchoring energy in grating-aligned twisted nematic liquid crystal layers
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Abstract
In this work sinusoidal diffraction gratings with a range of pitches and amplitudes are used to algin nematic liquid crystal layers in a twisted homogeneous configuration. The grating profiles are accurately characterized using optical surface plasmon polariton spectroscopy which then allows a calculation of the anchoring energy as predicted by the simple Berreman expression. The experimental Rapini-Papoular anchoring energy is also obtained by a measurement of the director twist away from the alignment direction at room temperature. A linear relationship is found between the two anchoring energies except when it falls below 4 X 10-7Jm-2. Noticeably, the correlation between the two theories is hot unity, if room temperature elastic constants are used in the calculation. This apparent inconsistency is explained if the effect of surface memory on the system is considered. Indeed if elastic constant, corresponding to a higher temperature, at which surface memory effects are absent, are used in the Berreman expression, good agreement between the predicted and experimentally measured energies is found.
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Emma L. Wood, Emma L. Wood, G. W. Bradberry, G. W. Bradberry, P. S. Cann, P. S. Cann, J. Roy Sambles, J. Roy Sambles, } "Determination of azimuthal anchoring energy in grating-aligned twisted nematic liquid crystal layers", Proc. SPIE 3318, Liquid Crystals: Physics, Technology, and Applications, (1 February 1998); doi: 10.1117/12.299984; https://doi.org/10.1117/12.299984
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