Determination of azimuthal anchoring energy in grating-aligned twisted nematic liquid-crystal layers
作者:
E. L. Wood,
G. W. Bradberry,
P. S. Cann,
J. R. Sambles,
期刊:
Journal of Applied Physics
(AIP Available online 1997)
卷期:
Volume 82,
issue 5
页码: 2483-2487
ISSN:0021-8979
年代: 1997
DOI:10.1063/1.366060
出版商: AIP
数据来源: AIP
摘要:
In this work sinusoidal diffraction gratings with a range of pitches and amplitudes are used to align 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 (easy axis) at room temperature. A linear relationship is found between the two anchoring energies, except when it falls below4×10−7 J m−2.Noticeably, the correlation between the two theories is not 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 constants, 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. ©1997 American Institute of Physics.
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