| Autor: |
Newsome, C. J., O'Neill, M. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 8/15/2002, Vol. 92 Issue 4, p1752, 5p, 5 Graphs |
| Abstrakt: |
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°. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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