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Proceedings Paper

Determination of anisotropy of diamagnetic susceptibility for nematics and polar anchoring energy coefficient for nematics: substrate systems by wedge cell method
Author(s): Jerzy Kedzierski; Zbigniew Raszewski; Marek Andrzej Kojdecki; Jerzy Zielinski; Emilia Miszczyk; Ludwika Lipinska
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Paper Abstract

A wedge cell of the wedge angle of order of few milliradians was used to measure threshold magnetic fields for the magnetic Freedericksz transition. A nematic liquid crystal filling the cell was of planar orientation enforced by the treatment of the flat boundary plates. A system of interference fringes appeared in the cell placed in normally incident light between analyzer and polarizer crossed. In the vicinity of each fringe the cell could be considered as a flat-parallel one and hence it was equivalent to a system of flat cells of different precisely determined thickness. The threshold magnetic field magnitudes were interpreted as eigenvalues of the boundary eigenvalue problem for the operator of second derivative; the interaction between the nematics and the substrate was described by the Rapini-Papoular formula (i.e. weak coupling was considered). The resulting formulae were used to determine the polar anchoring energy coefficient and the anisotropy of diamagnetic susceptibility after the threshold fields measured. The method was applied to characterize the nematic liquid crystal PCB and the coupling between it and the substrates made of poly(amic acid) MP2. The estimates of material parameters agreed pretty well with those determined by the composite method.

Paper Details

Date Published: 1 September 2004
PDF: 5 pages
Proc. SPIE 5565, XV Conference on Liquid Crystals, (1 September 2004); doi: 10.1117/12.581091
Show Author Affiliations
Jerzy Kedzierski, Military Univ. of Technology (Poland)
Zbigniew Raszewski, Military Univ. of Technology (Poland)
Marek Andrzej Kojdecki, Military Univ. of Technology (Poland)
Jerzy Zielinski, Military Univ. of Technology (Poland)
Emilia Miszczyk, Radom Univ. of Technology (Poland)
Ludwika Lipinska, Institute of Electronic Materials Technology (Poland)

Published in SPIE Proceedings Vol. 5565:
XV Conference on Liquid Crystals
Jozef Zmija, Editor(s)

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