Photo-patterned e-wave polarizer

Yip, W.C.; Kwok, Hoi‐Sing; Kozenkov, Vladimir M.; Chigrinov, Vladimir G.

doi:10.1016/s0141-9382(01)00051-8

Cited by 39 publications

(36 citation statements)

References 4 publications

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“…[2][3][4] A few reports are known on patterned polarizers based on the combination of lyotropic dyes and photoalignment layers. [5,6] In all cases the polarization performance is insufficient for almost all mainstream LCD applications (N < 25).Here we report on thin-film polarizers based on highly ordered guest-host systems. These thin-film polarizers hold all of the advantages mentioned above and can meet the polarization performance of traditional sheet polarizers (N > 50) at film thicknesses of only 5 lm, whereas conventional sheet polarizers have a thickness of approximately 100 lm.…”

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confidence: 95%

High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

et al. 2006

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The most essential passive optical element in liquid-crystal displays (LCDs) is the polarizer. Polarizers are indispensable for the displaying of the information content and important front-of-screen performance parameters, such as brightness and contrast, are strongly influenced by the performance of the polarizer. Currently, the most widely used polarizers for LCD applications are derivatives of the H-sheet polarizer as invented by E. H. Land in 1938.[1] These dichroic polarizers are based on uniaxially stretched poly(vinyl alcohol) that is impregnated with iodine or doped with dichroic dyes. These sheet polarizers show excellent optical performances that can be expressed by the polarization efficiency (PE) in combination with the single-piece transmittance (T sp ; transmission of unpolarized light through a single polarizer) aswhere T p and T c are defined as the transmission of unpolarized light through two polarizers with their transmission axis parallel and perpendicular, respectively, and where A ʈ and A ⊥ are defined as the absorbance parallel and perpendicular to the average orientation of the long axis of the chromophores, respectively. The polarizer performance can also be expressed by a single parameter; the dichroic ratio (N)For high-end sheet polarizers such as those applied in LCD monitors or flat-panel televisions, the performance exceeds a polarization efficiency (PE) of 99.9 % at a single-piece transmission of 43.5 %, corresponding to N exceeding 50. Unfortunately, two triacetylcellulose (TAC) layers are needed in conventional polarizers to protect the stretched poly(vinyl alcohol) film on both sides against moisture and to obstruct relaxation effects under influence of heat and/or humidity by which the PE value would deteriorate. Further, an adhesive layer is needed in order to laminate the polarizer to the display. The necessary use of protective and adhesive layers adds unnecessary thickness to H-sheet polarizers. Finally, these polarizers show limited thermal stability and low resistivity against solvents. Numerous advantages are foreseen when the traditional sheet polarizers are replaced by ultrathin coatable polarizers situated on the inside of the cell (in-cell). Apart from a significant reduction in display thickness and weight, the positioning of the polarizers inside the cell eliminates all parallax-related issues and is beneficial to the robustness of the display. Furthermore, substrates that otherwise would be rejected because of their birefringence, e.g., thin, low-weight, and strong plastic foils or cheap, low-quality glass substrates, can be used when the polarizers are situated inside the LCD cell. The optimal position of the coatable polarizers inside the LCD cells can vary between display designs, however, it is beneficial to place the polarizers beneath the electrodes in order to prevent the need for increased driving voltages of the LCD panels.One possible approach to obtaining thin, coatable polarizers is based on the use of lyotropic liquid-crystalline dyes that form a crys...

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High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

et al. 2006

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“…Following the early works of Dryer [18], different research groups have explored the possibility of using dye-based LCLCs in the fabrication of polarizing [19][20][21][22][23][24][25][26] and optical compensating elements [27,28]. The main feature allowing such an application is that when water evaporates, the resulting dry film still preserves an orientational order and thus anisotropic optical properties.…”

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confidence: 99%

Pretransitional fluctuations in the isotropic phase of a lyotropic chromonic liquid crystal

Nastishin

Liu²,

Shiyanovskii³

et al. 2004

Phys. Rev. E

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We have studied isotropic-to-nematic pretransitional fluctuations in an aqueous solution of disodium cromoglycate (cromolyn) by static and dynamic light scattering. Cromolyn is a representative of lyotropic chromonic liquid crystals with building units being elongated rods formed by aggregates of disk-like molecules. By combining light-scattering and viscosity measurements we have determined the correlation length and relaxation time of the orientational order-parameter fluctuations and estimated the size of the cromolyn aggregates. The pretransitional behavior of light scattering does not completely follow the classic Landau-de Gennes model. This feature is most probably associated with the variable length of cromolyn aggregates. We have observed a dramatic increase of the shear viscosity near the transition to the nematic phase, the fact which correlates with the idea of growing supramolecular aggregates. The steep temperature dependence of the viscosity is accompanied by a practically temperature-independent translational diffusion coefficient.

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“…Figure 7 shows photos of such a patterned polarizer. Patterned broadband polarizers were demonstrated in [22,23] using photoalignment of chromonic lyotropic LC dyes. In situ photopolymerization of reactive LC was used in [24] for producing thin high efficiency guest-host polarizers and patterning them using photoalignment techniques.…”

Section: Spectrally Selective Polarizersmentioning

confidence: 99%

Polarization Imaging Components Based on Patterned Photoalignment

Nersisyan

Tabiryan

2008

Molecular Crystals and Liquid Crystals

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The photoalignment technique was used for creating liquid crystal (LC) and LC polymer based polarization imaging components comprising areas of different orientation of optical axis. We discuss applications of such components for visualization of the state of polarization of a light beam and for producing microlens arrays. We used the technique also for producing patterns of cholesteric LCs (CLCs) with different azimuthal anchoring angle at the cell boundaries. The interface between different orientation states prove visible when viewed from the side of patterned orientation and they are invisible from the side of homogeneous planar orientation of the CLC.

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Photo-patterned e-wave polarizer

Cited by 39 publications

References 4 publications

High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

Pretransitional fluctuations in the isotropic phase of a lyotropic chromonic liquid crystal

Polarization Imaging Components Based on Patterned Photoalignment

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