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Optical measurements of the twist constant and angle in nematic liquid crystal cells

Optical measurements of the twist constant and angle in nematic liquid crystal cells
Optical measurements of the twist constant and angle in nematic liquid crystal cells

We present a reliable optical method for measuring the twist elastic constant K 2 and for assessing the total twist angle in a standard nematic twist cell. The method relies on the use of a non-standard configuration of crossed polarisers and a twist cell, which allows us to measure accurately the twist-cell parameters by reducing the degeneracy between them. Grid patching and an efficient beam propagation method are utilised in the numerical models used for fitting the experimental data. The modelling shows that the polarisation dynamics in a twist cell is non-trivial and much more complex than in a planar cell. The twist elastic constant of three commonly used liquid crystals (5CB, 6CHBT and E7) was successfully extracted from cross-polarised intensity measurements.

Liquid crystals, Nematic liquid crystals, optical measurement technique
2045-2322
Bankova, Denitsa
34388d3d-0094-4a1d-9297-49ce10fec1d3
Podoliak, Nina
0908b951-00a7-48a5-bc82-631640910b9c
Kaczmarek, Malgosia
408ec59b-8dba-41c1-89d0-af846d1bf327
D'alessandro, Giampaolo
bad097e1-9506-4b6e-aa56-3e67a526e83b
Bankova, Denitsa
34388d3d-0094-4a1d-9297-49ce10fec1d3
Podoliak, Nina
0908b951-00a7-48a5-bc82-631640910b9c
Kaczmarek, Malgosia
408ec59b-8dba-41c1-89d0-af846d1bf327
D'alessandro, Giampaolo
bad097e1-9506-4b6e-aa56-3e67a526e83b

Bankova, Denitsa, Podoliak, Nina, Kaczmarek, Malgosia and D'alessandro, Giampaolo (2024) Optical measurements of the twist constant and angle in nematic liquid crystal cells. Scientific Reports, 14 (1), [17713]. (doi:10.1038/s41598-024-68812-x).

Record type: Article

Abstract

We present a reliable optical method for measuring the twist elastic constant K 2 and for assessing the total twist angle in a standard nematic twist cell. The method relies on the use of a non-standard configuration of crossed polarisers and a twist cell, which allows us to measure accurately the twist-cell parameters by reducing the degeneracy between them. Grid patching and an efficient beam propagation method are utilised in the numerical models used for fitting the experimental data. The modelling shows that the polarisation dynamics in a twist cell is non-trivial and much more complex than in a planar cell. The twist elastic constant of three commonly used liquid crystals (5CB, 6CHBT and E7) was successfully extracted from cross-polarised intensity measurements.

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Accepted/In Press date: 29 July 2024
Published date: 31 July 2024
Keywords: Liquid crystals, Nematic liquid crystals, optical measurement technique

Identifiers

Local EPrints ID: 493724
URI: http://eprints.soton.ac.uk/id/eprint/493724
ISSN: 2045-2322
PURE UUID: e9cdf2f3-4bf3-49bf-af31-5ed1f2eaeb55
ORCID for Denitsa Bankova: ORCID iD orcid.org/0000-0002-2511-5133
ORCID for Nina Podoliak: ORCID iD orcid.org/0000-0002-3146-0355
ORCID for Giampaolo D'alessandro: ORCID iD orcid.org/0000-0001-9166-9356

Catalogue record

Date deposited: 11 Sep 2024 17:21
Last modified: 12 Sep 2024 01:59

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Contributors

Author: Denitsa Bankova ORCID iD
Author: Nina Podoliak ORCID iD

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