Digitale Medien
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
92 (2002), S. 1752-1756
ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
We discuss the formation of pretilt by oblique irradiation of photosensitive polymers that homogeneously align liquid crystals in the direction corresponding to the maximum density of unreacted polymer. We show that a tilted polymer distribution is formed by oblique illumination with one beam of unpolarized or partially polarized light. When unpolarized radiation is used, a small azimuthal anisotropy is generated and the polymer tilt angle increases with incident angle. Pretilted liquid crystal alignment is possible up to a threshold angle at which the azimuthal alignment direction changes. Irradiation with partially polarized light gives a higher azimuthal anisotropy but smaller polymer tilt angles. We obtain liquid crystal pretilt angles up to 4° by oblique irradiation of polyimide with light from an excimer laser operating below the threshold for ablation. A simple two step process is used to obtain pretilted alignment for liquid crystals using surface gratings: a grating etched into polyimide by laser ablation is subsequently irradiated at oblique incidence to give planar liquid crystal alignment with a pretilt angle of 3°. © 2002 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.1492863
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