21. |
Volt-Contrast Curve Anisotropy in Planar-Oriented Pdchlc Films |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 259-270
Vladimir Presnyakov,
Sergei Smorgon,
Victor Zyryanov,
Vasily Shabanov,
Preview
|
PDF (1335KB)
|
|
摘要:
The structural and electrooptical properties of planar-oriented films of polymer dispersed cholesteric liquid crystals with tangential orientation of molecules at the interface were investigated. It is shown, that in this medium, a great difference is observed between the threshold parameters and the form of both polarized components of the volt-contrast characteristic. This effect is due to the specific features of structural transformations of the elongated cholesteric droplets in the electric field.
ISSN:1058-725X
DOI:10.1080/10587259808025092
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
22. |
Measurement of Azimuthal Anchoring Energy of Nematic Liquid Crystal on Photoaligning Polymer Surface |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 271-281
D. Andrienko,
A. Dyadyusha,
A. Iljin,
Yu. Kurioz,
Yu. Reznikov,
Preview
|
PDF (430KB)
|
|
摘要:
A method to determine the surface azimuthal anchoring energy of a nematic liquid crystal is proposed. The technique implies the measurement of the director deviation on the cell substrate as a function of strength and direction of the applied magnetic field. As an example, the dependence of the azimuthal anchoring coefficient on the exposure time is measured at the interface between the nematic K 15 and polyvinylcinnamate film exposed by UV light. The analogous measurements performed in a wedge cell show that the method with magnetic field is more precise.
ISSN:1058-725X
DOI:10.1080/10587259808025093
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
23. |
Diffraction Gratings in a Nematic Cell Due to Spatial Variation of Surface Order Parameter |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 283-289
D. Andrienko,
I. Pinkevich,
Yu. Reznikov,
Preview
|
PDF (288KB)
|
|
摘要:
The influence of a periodical spatial modulation of asurfaceorder parameter on the distribution of the order parameter in a nematic liquid crystal bulk is studied. The problem is treated in the framework of the Landau - de Gennes theory with an anchoring energy in the formFS∼ (S-Q)2, where S is the NLC order parameter and Qis the surface order parameter. It is shown that the order parameter grating, which damps exponentially with the distance to the cell plates, appears in the cell bulk. The damping coefficient is inversely proportional to the coherence length ξ of the nematic-isotropic phase transition. Diffraction efficiency of this grating is proportional to (ξΔQ)2, where ΔQis an amplitude of the order parameter modulation, and is sufficient for experimental observations.
ISSN:1058-725X
DOI:10.1080/10587259808025094
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
24. |
Orientational Transitions in a Nematic Cell with Reverse Director Distributions |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 291-297
D. Andrienko,
Yu. Reznikov,
Preview
|
PDF (297KB)
|
|
摘要:
We predict orientational transitions in a nematic cell with co-directed and reversed orientations of easy axes on the aligning surfaces. Aside from aforwarddirector distribution there can exist thereversedistributions with zero and π/2 polar director angle at some point in the cell bulk. In the Rapini approach for the surface free energy these distributions can be unstable and transition two the forward distribution can occur. Dimensionless parameters, controlling the director distribution are the easy axis angle and an anchoring strength parameterWL/K.
ISSN:1058-725X
DOI:10.1080/10587259808025095
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
25. |
Light-Induced Anchoring Transitions and Bistable Nematic Alignment on Polysiloxane-Based Aligning Surface |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 299-307
D. Andrienko,
A. Dyadyusha,
Yu. Kurioz,
V. Reshetnyak,
Yu. Reznikov,
Preview
|
PDF (387KB)
|
|
摘要:
We report a novel azimuthal anchoring transition of nematic liquid crystal on a polysiloxane-cinnamate treated surface under the UV irradiation. It is found, that the direction of the light-induced easy axis strongly depends on the irradiation time. Under short exposure times the orienting surface provides an orientation of LC parallel to the direction of the UV light polarization. Longer times give the orthogonal to the UV polarization orientation of LC. There is a region of exposure times that give a bistable anchoring conditions and domains with different directions of the director orientation. We propose a phenomenological model of this anchoring transition and surface bistability based on the competition between trans-cis isomerisation of the side fragments of the polysiloxane-cinnamate material and cross-linking photoreaction of the trans-form of side fragments resulting in orthogonal molecular easy axes.
ISSN:1058-725X
DOI:10.1080/10587259808025096
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
26. |
A Liquid Crystal Broad Band Stokes-Meter |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 309-316
Jörg Schirmer,
Peter Kohns,
Theodor Schmidt-kaler,
Preview
|
PDF (313KB)
|
|
摘要:
A device for the determination of the complete polarization state of light in a broad spectral interval is presented. Two tunable achromatic phase retarders with planar aligned nematic liquid crystals are used to modulate the polarization without moving components.
ISSN:1058-725X
DOI:10.1080/10587259808025097
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
27. |
A Novel Technique for Optical Imaging of Liquid Crystal Alignment Layers |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 317-322
Ju-Hyun Lee,
Chang-Jae Yu,
Sin-Doo Lee,
Preview
|
PDF (385KB)
|
|
摘要:
We have employed a phase modulation method using a photoelastic modulator to determine the uniformity and quality of the alignment layer of liquid crystals (LCs). It is demonstrated that a two-dimensional map of the phase retardation, associated with irregular rubbing and/or chemical contaminants, provides invaluable information about an early detection of defects involved for aligning the LC molecules on a substrate.
ISSN:1058-725X
DOI:10.1080/10587259808025098
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
28. |
Optical Effects in Polymer-Dispersed Liquid Crystal - Fibre Optic Devices |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 323-331
StanisławJ. Kłosowicz,
LeszekR. Jaroszewicz,
Edward Nowinowski-kruszelnicki,
Preview
|
PDF (483KB)
|
|
摘要:
Optical effects in PDLC - fibre optic systems have been studied. The main attention is devoted to intensity modulation based upon electrically driven transmittance and switching effects based upon grating structures in PDLC films. Obtained results are discussed from application point of view.
ISSN:1058-725X
DOI:10.1080/10587259808025099
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
29. |
Molecular Orientation of Perylene-Like Dyes in Liquid Crystal 80CB |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 333-347
Danuta Bauman,
Ewa Mykowska,
Eryk Wolarz,
Preview
|
PDF (499KB)
|
|
摘要:
The polarized absorption and fluorescence spectra of some dichroic fluorescent dyes (derivatives of 3,4,9-perylenetricarboxylic acid and 3,4,9,10-perylenetetracarboxylic acid) oriented in liquid crystal 80CB have been recorded as a function of temperature. On the basis of these spectra the order parameters <P2> and <P4> and orientational distribution function have been determined. The conclusions about the influence of the molecular structure of the dyes on their orienting properties in uniaxial liquid crystalline phases have been drawn.
ISSN:1058-725X
DOI:10.1080/10587259808025100
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|
30. |
Diffraction Gratings, Liquid Crystals and Guided Modes |
|
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals,
Volume 321,
Issue 1,
1998,
Page 349-358
J.Roy Sambles,
EmmaL. Wood,
Preview
|
PDF (385KB)
|
|
摘要:
The use of optical excitation of guided modes to study the director profile in thin liquid crystal layers is well established. The most commonly used coupling geometry is that of prism-coupling, the prism providing the required extra in-plane momentum to allow coupling between the external radiation and the guided modes in the liquid crystal layer. A second coupling arrangement involves the use of a grating to provide the extra in-plane momentum by diffraction. Optical modelling of grating structures with liquid crystal layers is by no means as easy as modelling the planar prism-coupled system. In this article we examine both experiments involved with, and the theoretical modelling of, grating coupling to guided modes in liquid crystals.
ISSN:1058-725X
DOI:10.1080/10587259808025101
出版商:Taylor & Francis Group
年代:1998
数据来源: Taylor
|