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Proceedings Paper

Determination of nematic liquid crystal material parameters by use of wedge cells
Author(s): Jerzy Kedzierski; Marek Andrzej Kojdecki; Zbigniew Raszewski; Ludwika Lipinska; Jolanta Rutkowska; Emilia Miszczyk; Jerzy Borycki
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Paper Abstract

Three wedge cells of the wedge angle of order of few milliradians were used to measure the phase shift between ordinary and extraordinary ray of transmitted light, for the stationary states, induced by magnetic or electric field. A nematic liquid crystal PCB, filling the cell, was of the planar alignment enforced by the previous treatment of the flat boundary plates. Two polyimides, MP9 and PM2, and clean glass were used as aligning substances. A system of interference fringes appeared in each cell placed in normally incident light between analyzer and polarizer crossed. In the neighborhood of each fringe a cell was considered as a flat-parallel one and hence it was equivalent to a system of flat cells of different precisely determined thickness. The dependence of the phase shift on applied external fields was measured for twenty-six interference fringes. The nematic liquid crystal material parameters (the splay and bend elastic constants, the anisotropy of diamagnetic susceptibility and the boundary tilt angle as a function of torque) were determined by comparing the calculated characteristics to the measured ones i.e. by solving the inverse problem simultaneously for all measured characteristics as input data. Each of studied cells represented distinct case of anchoring: strong, medium or weak.

Paper Details

Date Published: 1 September 2004
PDF: 6 pages
Proc. SPIE 5565, XV Conference on Liquid Crystals, (1 September 2004); doi: 10.1117/12.581140
Show Author Affiliations
Jerzy Kedzierski, Military Univ. of Technology (Poland)
Marek Andrzej Kojdecki, Military Univ. of Technology (Poland)
Zbigniew Raszewski, Military Univ. of Technology (Poland)
Ludwika Lipinska, Institute of Electronic Materials Technology (Poland)
Jolanta Rutkowska, Military Univ. of Technology (Poland)
Emilia Miszczyk, Radom Univ. of Technology (Poland)
Jerzy Borycki, Radom Univ. of Technology (Poland)

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

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