Description
- Abstract:
- This dissertation utilizes holographic exposure techniques to manipulate the periodic orientation of liquid crystal materials. Two different exposure techniques are investigated: a polarization holography interference method incident on a photo-responsive surface to induce a preferential ordering, and an amplitude holography interference method that relies on a phase separation and counter-diffusion reaction to create stratified regions of liquid crystal and polymer. In the phase holography investigations, a linear photopolymerizable (LPP) layer is selectively polymerized permanently capturing phase information from the interference patterning and transferring it to align a liquid crystal material. The underlying periodic and frustrated alignment in the one- and two-dimensional alignment configurations is discussed, including the nature of their electro-optic switching transitions. A phenomenological model is presented to describe the Freedericksz transition, or lack thereof, for the registered planar-periodic boundary conditions resulting from the interference of two orthogonal circularly polarized beams. In the amplitude holography investigations, the frustrated chiral and smectic ordering of ferroelectric liquid crystal domains encapsulated by a polymer binder were established. The refractive index modulation in these thin films is modeled as a phase grating that can be electrically addressed to erase the optical diffractive properties. A phenomenological model is developed to take into account a distribution of domain sizes and an effective field that stabilizes the ferroelectric liquid crystal domains. A diffraction model successfully predicts changes in normalized intensities for first-order diffraction with applied field. These gratings demonstrate microsecond-scale response and relaxation times for various grating pitch sizes between 3 and 12 micrometers.
- Notes:
- Thesis (Ph.D.) -- Brown University (2008)
Access Conditions
- Rights
- In Copyright
- Restrictions on Use
- Collection is open for research.
Citation
Eakin, James Nelson,
"Photo-Patterning Studies for Liquid Crystal Alignment"
(2008).
Engineering Theses and Dissertations, Electrical Sciences and Computer Engineering Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0P8496Z
Relations
Collections:
-
-
Electrical Sciences and Computer Engineering Theses and Dissertations
Theses and Dissertations for the Electrical Sciences and Computer Engineering department....