Study of anchoring characteristics and splay-bend elastic constant based on experiments with non-twisted nematic liquid crystal cells

Opto-Electronics Review - Tập 16 - Trang 390-394 - 2008
J. Kędzierski1, M. A. Kojdecki2, Z. Raszewski1, J. Rutkowska1, W. Piecek1, P. Perkowski1, J. Zieliński1, E. Miszczyk3
1Institute of Applied Physics, Military University of Technology, Warsaw, Poland
2Institute of Mathematics and Cryptology, Military University of Technology, Warsaw, Poland
3Institute of Physics, Radom University of Technology, Radom, Poland

Tóm tắt

Possible influence of a nematics splay-bend elastic constant and corresponding free energy functional term on adequacy of description of nematics states is studied by comparing results of theoretical considerations and computer simulations with experimental data. Planar deformation states enforced in flat nematics cells by symmetric aligning cover coatings and external electric or magnetic fields are studied in one-dimensional approximation. Nematics material parameters and nematics-substrate coupling characteristics are determined from experimental data by immediate measurement or by solving inverse problems. Two series of cells with thicknesses between twenty and forty-four micrometers (in fact two wedge cells) with two different orienting substrates are investigated by measuring a cell optical response in a birefringence experimental system. Good agreement between optical retardation measured and simulated is observed. Posterior comparison of free energy contributions from substrate interactions and a hypothetical surface-like term leads to a conclusion that the last one together with a splay-bend elastic constant should be very small and can be neglected.

Tài liệu tham khảo

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