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          33/<i>K</i>11 determination in nematic liquid crystals: An optical birefringence technique

Crawford, G. P.; Mitcheltree, J. A.; Boyko, E. P.; Fritz, William J.; Žumer, S.; Doane, J. William

doi:10.1063/1.106701

Cited by 22 publications

(11 citation statements)

References 10 publications

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“…while the disclination can be confined inside an isotropically transparent cylindrical vessel [14]. The effect of a transparent isotropic medium (the vessel) on the light will be that of a lens and is neglected here [15,16]. Despite of the common knowledge of the 3D-escape of the director for the (k=1,c=0) disclination, we assume a stable disclination due two reasons.…”

Section: Geometric Modelmentioning

confidence: 99%

Diffraction of light by topological defects in liquid crystals

Pereira

Moraes

2011

Liquid Crystals

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We study light scattering by a hedgehog-like and linear disclination topological defects in a nematic liquid crystal by a metric approach. Light propagating near such defects feels an effective metric equivalent to the spatial part of the global monopole and cosmic string geometries. We obtain the scattering amplitude and the differential and total scattering cross section for the case of the hedgehog defect, in terms of the characteristic parameters of the liquid crystal. Studying the disclination case, a cylindrical partial wave method is developed. As an application of the previous developments, we also examine the temperature influence on the localization of the diffraction patterns.

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Section: Geometric Modelmentioning

confidence: 99%

Diffraction of light by topological defects in liquid crystals

Pereira

Moraes

2011

Liquid Crystals

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“…Different structures for cells with different thicknesses can also be forecast theoretically and revealed experimentally with the use of polarizing optical microscopy [12,13]. The essence of the optical polarizing microscopy is the following.…”

Section: Resultsmentioning

confidence: 99%

“…These patterns correspond to spin configurations illustrated inFigures 1 and 2. The laser wavelength 445 nm was arbitrary chosen, and the ordinary and extraordinary refraction indices 1.544 and 1.821 correspond to NLC E7[12,13]. The real thickness was set to h = 2 m for the L = 10 cell and 6 m for the L = 30 cell.…”

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confidence: 99%

Thickness Induced Line-Defect Reconfigurations in Thin Nematic Cell

Ambrožič

Kralj

2019

Advances in Condensed Matter Physics

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We studied the impact of the cell thickness on configurations of line disclinations within a plane-parallel nematic cell. The Lebwohl-Lasher semimicroscopic approach was used and (meta)stable nematic configurations were calculated using Brownian molecular dynamics. Defect patterns were enforced topologically via boundary conditions. We imposed periodic circular nematic surface fields at each confining surface. The resulting structures exhibit line defects which either connect the facing plates or remain confined within the layers near confining plates. The first structure is stable in relatively thin cells and the latter one in thick cells. We focused on structures at the threshold regime where both structures compete. We demonstrated that “history” of samples could have strong impact on resulting nematic configurations.

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“…As in any confined environment, the system has to adopt a director field that is a compromise between the competing demands of director anchoring, surface curvature and the need to minimise the excess elastic energy within the system [29]. Cross-sections of director fields commonly seen in cylindrical confinement (fibres) [30,31] are shown schematically in Figures 2 and 3. When there is perpendicular anchoring at the surface, the simplest director field imaginable is the "planar radial" field ( Figure 2a).…”

Section: Introductionmentioning

confidence: 99%

Textures of Nematic Liquid Crystal Cylindric-Section Droplets Confined by Chemically Patterned Surfaces

et al. 2021

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The director fields adopted by nematic liquid crystals (LCs) that are confined by the surface to form long, thin droplets are investigated using polarising optical microscopy. Samples are produced by de-wetting of the LC on a surface patterned with alternating high-surface energy and low-surface energy stripes of 10–30 μm width. The droplets obtained are expected to adopt a profile which is that of a longitudinal section of a cylinder and, as this suggests, the director fields observed are variants in the case where the LC is constrained in a cylindrical capillary or fibre. Hence, when there is normal anchoring at the air interface, the textures observed are related to the well-known escaped radial texture (for the nematic LC mixture E7) or plane polar texture (for the LC mixture MLC6609). More surprising is the observation that the nematic LC mixture MLC7023, which is anchored in a planar or tilted manner at the air interface, also gives what appears to be an escaped radial director field. As an exploration of the possibility of using these systems in creating sensors, the effects of adding a chiral dopant and of adding water to the substrates are also investigated.

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K 33/K11 determination in nematic liquid crystals: An optical birefringence technique

Cited by 22 publications

References 10 publications

Diffraction of light by topological defects in liquid crystals

Diffraction of light by topological defects in liquid crystals

Thickness Induced Line-Defect Reconfigurations in Thin Nematic Cell

Textures of Nematic Liquid Crystal Cylindric-Section Droplets Confined by Chemically Patterned Surfaces

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