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Proceedings Paper

Polymer Dispersed Liquid Crystals Incorporating Isotropic Dyes
Author(s): John L. West; Winifred Tamura-Lis; Renate Ondris
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Paper Abstract

Colored polymer dispersed liquid crystal, PDLC, shutters are formed by the inclusion of isotropic dyes in the epoxy resin and liquid crystal used to make the shutter. Upon curing, the dye is dissolved in both the epoxy binder and the liquid crystal droplets. The shutters are highly colored and scattering in the absence of an aligning electric field, OFF state. Application of an electric field across the film aligns the director of the liquid crystal in the droplets, switching the shutter to a lightly colored, transparent, ON state. In the ON state, light passes through the film unscattered and its path length is essentially equal to the thickness of the cell. In the scattering, OFF, state the path length of light is increased due to Rayleigh-Gans and multiple scattering. The optical density, OD, of the shutter is directly proportional to the path length of the light. The shutter OD is measured in both the ON and OFF states using a LTV-visible spectrophotometer equipped with an integrating sphere and an undyed PDLC shutter used as a reference. The ratio of the OD in the OFF to the ON state is a direct measure of the scattering efficiency of the shutter. Using this ratio, it is possible to calculate the dye concentration that will maximize the change in percent transmission through the film between the ON and OFF states. High contrast, colored displays have been made using isotropic dye containing PDLC films and complementary colored backgrounds.

Paper Details

Date Published: 25 July 1989
PDF: 5 pages
Proc. SPIE 1080, Liquid Crystal Chemistry, Physics, and Applications, (25 July 1989); doi: 10.1117/12.976400
Show Author Affiliations
John L. West, Kent State University (United States)
Winifred Tamura-Lis, Kent State University (United States)
Renate Ondris, Kent State University (United States)

Published in SPIE Proceedings Vol. 1080:
Liquid Crystal Chemistry, Physics, and Applications
J. William Doane; Zvi Yaniv, Editor(s)

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