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Proceedings Paper

Photoinduced and grating alignment of polyimide using excimer lasers for liquid crystal displays
Author(s): Christopher J. Newsome; Mary O'Neill; Guy P. Bryan-Brown
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Paper Abstract

Recently there has been renewed interest in the grating alignment of liquid crystals because of its application in bistable nematic displays. In this paper, gratin and photoinduced liquid crystal alignment techniques based on excimer laser exposure of thin polyimide films are discussed. Gratings are etched into the alignment film using a KrF laser illuminated through a phase mask. These give homogeneous liquid crystal alignment with the liquid crystal directors aligned along the grooves of the grating. The observed azimuthal anchoring strength is compared with that predicted using Berreman theory. No pretilt is observed because of the grating symmetry. When a polarized excimer laser beam is incident on the film with a fluence below that required for ablation, an anisotropy is created photochemically by selective depletion of the polymer chains. Exposure of the polyimide with elliptically polarized light at non-normal incidence gives pretilted alignment. Grating etching followed by photoinduced alignment can be used to obtain pretilted grating alignment with a pretilt angle of 3 degrees.

Paper Details

Date Published: 15 July 1999
PDF: 9 pages
Proc. SPIE 3618, Laser Applications in Microelectronic and Optoelectronic Manufacturing IV, (15 July 1999); doi: 10.1117/12.352677
Show Author Affiliations
Christopher J. Newsome, Univ. of Hull (United Kingdom)
Mary O'Neill, Univ. of Hull (United Kingdom)
Guy P. Bryan-Brown, Defense Evaluation and Research Agency (United Kingdom)

Published in SPIE Proceedings Vol. 3618:
Laser Applications in Microelectronic and Optoelectronic Manufacturing IV
Jan J. Dubowski; Henry Helvajian; Ernst-Wolfgang Kreutz; Koji Sugioka, Editor(s)

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