• Title/Summary/Keyword: Cholesteric liquid crystal

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Improving switching time from homeotropic state to planar state in cholesteric liquid crystal by olymer stabilization

  • Kim, Tae-Jin;Lim, Tong-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.437-438
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    • 2005
  • A polymer stabilization method is employed to reduce the transition time from field-induced homeotropic(H) state to reflecting planar(P) state in the cholesteric liquid crystal(ChLC) display. To stabilize ChLC by polymer, we mixed ChLC with diacrylate of 2 $wt%{\sim}6$ wt%. Two samples were made with different method of stabilization. For one sample the diacrylate of 2 wt% was polymerized with the ChLC in P state, while for the other sample diacrylate of 16 wt% was polymerized with ChLC in H state. In the former case, the transition time was 1000 times faster then those in the pure sample. In the latter sample, the transition time was 1700 times faster than those in pure ChLC sample.

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Femtosecond nonlinear optical shift in photonic bandgapedges of a cholesteric liquid crystal (롤레스테릭 액정의 광결정 가장자리에서의 펨토초 비선형 광학 이동)

  • Jisoo Hwang;N. Y. Ha;H. J. Chang;Park, Byoungchoo;J. W. Wu
    • Proceedings of the Optical Society of Korea Conference
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    • 2003.07a
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    • pp.164-165
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    • 2003
  • A cholesteric liquid crystal (CLC) system exhibits one-dimensional (1-D) Photonic bandgap (PBG) characteristics in the transmission spectrum through a selective Bragg reflection. Related to the nonlinear optical (NLO) processes in a PBG structure of CLC, the inherent periodicity has been exploited to Phase-match the fundamental and the harmonic waves through the umklapp Processes. Near bandgap edges of a CLC, harmonic generations have been shown to be enhanced significantly through the field localization. (omitted)

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Membrane from Liquid Crystal Composite of Cellulose Acetate and Poly (4-vinyl pyridine) (셀룰로오스 아세테이트와 폴리비닐 피리딘 액정중합체의 박막에 관한 연구)

  • Hong, Young-Keun;Cho, Bong-Heuy
    • Textile Coloration and Finishing
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    • v.3 no.2
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    • pp.43-48
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    • 1991
  • Cellulose acetate (CA) and poly-4-vinyl pyridine (PVP) in various weight proportions were mixed in a mixed solvent of trifluoroacetic acid: methylene chloride/6:4 (v:v). CA was miscible with PVP in that solvent system. CA/PVP/solvent show liquid crystal in a certain range of concentration and the nature of that liquid crystal was cholesteric. Films of the liquid crystal composite cast from the liquid crystal solutions of CA/PVP were tested in a viewpoint of biomembrane. Results show that considering permselectivity CA/PVP membrane is better than that of CA and CA/PVP membrane is closer to cell membrane.

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New Flexible Applications Using $Reflex^{TM}$ Display Technology

  • Khan, Asad;Davis, Donald J.;Ernst, Todd;Marhefka, Duane;Miller, Nick;Montbach, Erica;Pishnyak, Oleg;Schneider, Tod;Doane, J.W.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.167-170
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    • 2008
  • $Reflex^{TM}$ display technology based on bistable, reflective, and flexible Cholesteric Liquid Crystal Displays is being developed and mass produced for new and non-traditional applications. These applications allow for personalization of mobile devices, very low cost display systems, and more. This display technology, its status, and new applications are discussed in this paper.

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Pitch Variations in Cholesteric Liquid Crystals by Phase Separation (상 분리에 의한 콜레스테릭 액정의 피치 변화)

  • Park Han-Soo;Kim Beom-Kyung;Kim Whan-Ki;Kim In-Sun;Song Ki-Gook
    • Polymer(Korea)
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    • v.30 no.2
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    • pp.182-186
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    • 2006
  • Due to their periodic helical structure, cholesteric liquid crystals (CLC) have a unique ability to selectively reflect light. CLC films reflecting a broad wavelength band were prepared by inducing a pitch gradient in CLC layer through a phase separation. The reflection bandwidth of the CLC cell was broaden as irradiation light intensity decreased and as the amount of the UV absorbing dye increased. Initial reflection bandwidth of 50 nm was broaden to 300 nm Various pitch distributions in the CLC cell was observed using SEM and ATR-IR technique was used to prove that the pitch distributions are induced through the phase separation.

Fiber optic circular polarizing mirror using polymer cholesteric liquid crystal and it's application in the mode-locked fiber laser (콜레스테릭 액정 폴리머 박막을 이용한 광섬유 원편광 거울 제작 및 이를 이용한 모드 록킹 된 광섬유 레이저)

  • 장도일;김경헌;김인선;김성태
    • Korean Journal of Optics and Photonics
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    • v.11 no.2
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    • pp.91-96
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    • 2000
  • We propose a novel in-line fiber optic circular polarizing mirror utilizing cholesteric lIquid crystal (CLC) polymer [11m for the fiber laser applications. Ions matrix representation of this device has been derived and venfied experimentally. In a Fabry-Perot cavity configuration, a CLC fiber optic rmrror has been used to achieve longitudinal mode suppression as well as to obtain passively mode~locked laser operations with 630 fs laser pulses via nonlinear polarization evoluhon.oluhon.

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FLEXMatters;A Consortium for Production of Flexible Devices

  • West, John L.;Khan, Asad
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.203-206
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    • 2007
  • The FLEXMatters initiative is building a collaboration of companies and universities to develop and produce flexible devices. Kent Displays leads the production of flexible displays using their bistable cholesteric technology. The FLEXMatters members are collaborating to develop the flexible manufacturing process that will are common to a wide variety of devices.

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Electro-controllable omni-directional laser emissions from a helical polymeric network composite film

  • Jang, Won-Gun;Park, Byoung-Choo;Kim, Min-A;Kim, Sun-Woong;Kim, Yun-Ki;Choi, Eun-Ha;Seo, Yoon-Ho;Cho, Guang-Sup;Kang, Seung-Oun;Takezoe, Hideo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.883-886
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    • 2008
  • In optical information technology, an electro-controllable Photonic Band Gap (PBG) in a photonic crystal (PC) material is potentially useful for the manipulation of light. Despite a great deal of research on PBGs, the reliable use of electro-active PBG material systems is restricted to only a few cases because of the complex and limiting nature of the structures involved. Here, we propose a PBG system that uses a liquid crystal (LC) polymer composite. The composite is made of nematic LCs (NLCs) embedded in polymeric helical networks of photo-polymerized cholesteric LCs (CLCs). The composite film shows a large field-induced reversible color shift over 150 nm of the reflection band, due to the reorientational undulation of the helical axis, similar to the Helfrich effect.

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A Study of the Stability and Moisturizing Effect of Non-Animal Cholesteric Liquid Crystal (비동물성 콜레스테릭 액정의 안정성과 보습효능에 관한 연구)

  • Woo, Byoung Young;Min, Dae Jin;Baek, Heung Soo;Kim, Shin Hyoung;Hwang, Joon Young;Park, Young Ho;Lee, John Hwan;Shin, Song Seok
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.40 no.2
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    • pp.141-153
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    • 2014
  • This study is about the development of cholesteric liquid crystals (CLCs), which are highly applicable to cosmetics formulation. The CLCs made from non-animal origin were chosen not only because they are free of animal viruses but also because they give a sense of security to the cosmetic consumers. Three kinds of new cholesteric derivatives (CI, CC, CN) were synthesized using non-animal cholesterol [NAB cholesterol (ARCH LONZA)], which was originally made by fermentation process. To develop high applicability to cosmetics formulation, we attempted to find out the optimum compositions in which CLCs can maintain their color over a wide range of temperature. The CLCs in 41 different compositions were prepared by the combinations of three cholesteric derivatives and a visual evaluation method was employed to determine the range of temperature at which the CLCs display their color. The 205 UV-VIS spectral data obtained from 41 CLCs at various temperatures were simultaneously analyzed to investigate the critical factors affecting the characteristics of the CLCs. Results showed that A4, A5, A6 and A7 were the best compositions to cosmetics formulation. A6 composition had a great moisturizing effect by the artificial skin test ($AmoReSkin^{TM}$).