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Proceedings Paper

Azimuthal anchoring energy of liquid crystals aligned using laser-ablated gratings in polyimide
Author(s): Christopher J. Newsome; Mary O'Neill; Robert J. Farley; Guy P. Bryan-Brown
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Paper Abstract

Gratings etched into polyimde thin layers are used to align nematic liquid crystals. The gratings are prepared by illumination of a 1.1 micrometer period phase mask with a KrF excimer laser at 248 nm. Fluences of 87 mJ cm-2 and 128 mJ cm-2 with one and two shots were used to ablate the gratings. Modelling of the fluence distribution behind the phase mask predicts a grating period equal to that of the phase mask and this is found experimentally. The amplitudes of the gratings are obtained from diffraction using a HeNe laser and are between 100 nm and 150 nm deep. The alignment layers are used in twisted nematic cells and the azimuthal anchoring energy is measured as a function of grating fabrication conditions. Anchoring energies of the order of 10-5 J m-2 are found in agreement with the Berreman theory.

Paper Details

Date Published: 1 April 1998
PDF: 7 pages
Proc. SPIE 3297, Liquid Crystal Materials, Devices, and Applications VI, (1 April 1998); doi: 10.1117/12.304542
Show Author Affiliations
Christopher J. Newsome, Univ. of Hull (United Kingdom)
Mary O'Neill, Univ. of Hull (United Kingdom)
Robert J. Farley, Univ. of Hull and Defence Evaluation and Research Agency (United Kingdom)
Guy P. Bryan-Brown, Defense Evaluation and Research Agency (United Kingdom)

Published in SPIE Proceedings Vol. 3297:
Liquid Crystal Materials, Devices, and Applications VI
Ranganathan Shashidhar, Editor(s)

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