共查询到20条相似文献,搜索用时 93 毫秒
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激光散射和光电子技术是目前测试液晶特性最先进和可靠的手段.此技术通过静态光散射和动态光散射两种测试方法,测得液晶的分子量、浊度系数、相关长度、相变温度、展矩和扭矩等许多物理参数,因此可判断液晶的类型,了解液晶的结构、形态,相转移及动态变形的过程,为液晶在许多领域的应用提供可靠的理论依据. 相似文献
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相位型液晶空间光调制技术已经广泛应用于自适应光学、信息光学等领域,然而一直存在着响应速度较低的问题。为了提高相位型液晶空间光调制器的响应速度,采用聚合物网络液晶制备近红外波段亚毫秒响应相位调制器,并对其光散射特性和瞬态响应特性进行了研究。通过降低聚合反应温度并提高紫外(UV)固化照度,可以降低器件的光散射强度,实现较好的相位调制。在此基础上,初步研究了聚合物网络形貌对最大光散射强度的影响。在高电压加载下,聚合物网络的电致伸缩效应会极大降低聚合物网络液晶的响应速度,使其达到秒级,经分析认为通过采用高介电各向异性的液晶材料可以降低阈值电压,提高器件的响应速度。 相似文献
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外加电场可以改变液晶膜的透光性能,这称为液晶的电光效应.目前应用于显示技术上的液晶的电光效应一般为扭曲效应或动态散射效应.但这两类效应或者对外电场的响应速度慢,或者对比度不佳,往往不能满足显示的要求.我们利用电场诱导下的胆甾相与向列相间的相变效应[1],制成的液晶光阀可克服上述缺点,满足快速、高对比度、低功耗的显示技术要求.电场诱导下的胆甾相与向列相间的相变过程中,一般经历着三种不同的结构状?... 相似文献
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基于偏振门的动态光散射颗粒测量法的研究 总被引:1,自引:1,他引:0
为了解决动态光散射纳米颗粒测量技术无法测量高浓度颗粒粒径的难题,提出了一种基于偏振门的动态光散射测量法。从动态光散射和Mie理论出发,理论分析了在高浓度溶液下多重散射效应对散射光偏振态和颗粒粒度测量结果的影响。根据散射光偏振特点,结合偏振门检测技术,改进了传统的动态光散射光学系统。实验研究了在低浓度和高浓度溶液时,不同偏振角度下的散射光强和粒度测量值,完善了散射光的偏振理论。采用90°偏振门检偏,通过各种浓度下的实验,证明了方法的可行性。该方法较之目前同类方法具有原理和结构简单,系统易于维护的特点。 相似文献
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铁电液晶缺陷光子晶体调谐滤波器的设计 总被引:2,自引:0,他引:2
将铁电液晶作为缺陷层引入一维光子晶体中,用电场改变液晶分子的取向,形成光子晶体快速可调谐滤波器.用传输矩阵法研究了铁电液晶缺陷光子晶体的可调谐滤波特性,计算了电压和液晶材料参量对滤波器透射谱的影响.结果表明:改变电压能容易改变光子晶体滤波器透射峰的位置、强度、个数和带宽,实现良好的调谐滤波功能. 相似文献
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选用双轴性并含有多个手征中心的分子作用势,引入手征中心分布结构因子ζχ,采用格胞模型,求得液晶SmC*相的螺距表达式和螺旋性反转条件.计算了TDOBAMBCC,FLC,PACMB和H6/10等4种典型SmC相液晶的螺距随温度的变化及其受ζχ的影响.结果与实验相符.
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《中国物理快报》2016,(10)
Ultrashort pulses complicate the frequency conversion in a nonlinear crystal,where group velocity mismatch becomes the main obstacle due to dispersion.We present a design for group velocity compensated second harmonic generation in a modulated nonlinear structure,embedded in a liquid crystal box.In this structure,nonlinear crystals act as sources of signal and liquid crystals compensate for group velocity mismatch originating from nonlinear crystals.There are the advantages of the flexible,controllable birefringence of liquid crystals.Meanwhile,a method calculating the parameters of this type of structure is presented.To make it clear,an example is provided.Furthermore,the structure can also be shaped as a waveguide to support integration into other optical devices,applicable to all-optical processing systems. 相似文献
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We examine the effect of shear flow on the orientational phase transitions induced by a magnetic field in ferronematic liquid crystals. Continuum approach based on the generalized Leslie–Ericksen theory is used to describe the dynamics of ferronematic liquid crystals. We consider three orientations of the magnetic field in a plane of shear flow. Stationary solutions for the director and the magnetization are obtained as functions of the magnetic field strength for different values of material parameters. Our results show that shear flow can lead to the shift of the field thresholds or to a “smoothing” of the magnetic field-induced transitions in ferronematics. In the limiting case of pure nematic liquid crystals, we revealed threshold effects, which are unstipulated by the orientational elasticity of a liquid crystal, in contrast to the conventional Fréedericksz transition. 相似文献
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The propagation velocity and absorption coefficient of ultrasound in the range of 0.6–150 MHz in a series of liquid crystal
emulsions prepared on the basis of thermotropic liquid crystals and isotropic liquids were studied. The dispersity parameters
of emulsions were controlled by polarization microscopy and dynamic light scattering. Features of the temperature dependences
of the acoustic parameters of emulsions due to the structural transformations and nematic-isotropic liquid transition in disperse
and dispersion phases of liquid crystal emulsions were established. 相似文献
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Yasuo Ito Yasuhiro Miyake Yoneho Tabata Bill W. Ng John M. Stadlbauer David C. Walker 《Hyperfine Interactions》1984,18(1-4):733-738
The diamagnetic and muonium fractions and their decay constants were measured for cyclohexane, neopentane andn-hexane for the temperature region covering liquid, plastic and non-plastic crystals. The muon and muonium parameters were almost the same for liquids and plastic crystals, but they showed a marked change in non-plastic crystals; a rapid decay of Mu precession, relaxation of the diamagnetic muon component and an increase in the lost polarization have been found to be characteristic of non-plastic crystals. 相似文献
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TU Mei & HUANG Yaoxiong Institute of Biomedical Engineering Jinan University Guangzhou China Correspondence should be addressed to Huang Yaoxiong 《中国科学G辑(英文版)》2004,47(1)
Theelasticconstantsandtheviscositycoefficientsarethekeyparametersforthephysicalpropertiesofnematicliquidcrystals(LCs)[1,2],fortheyarecorrespondingtothethresholdvoltageandtherespondingtimeofliquidcrystaldisplaydevices[3,4].Sofarnotechniquethatcansimultaneouslymeasurethetwoparametersinsituhasbeenreported.TheelasticconstantsandviscositycoefficientsofnematicLCsatthepresentaremeasuredusingdifferentmethodsindependently.TheviscositycoefficientsisgenerallymeasuredwithOstwaldviscosimeter,andtheelasti… 相似文献
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The liquid crystal technology is one of the most popular at the present time. To the most important parameters of liquid crystals
belong optical anisotropy, viscosity, and twist elastic constants. One of the most difficult and problematic to measure parameters
is a twist elastic constant K22. For new liquid crystalline materials, we have to characterize their physical properties, also a twist elastic constant K22. 相似文献
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The possibility of determining the relaxation time of cholesteric liquid crystals with a large helix pitch from the parameters of acoustic streaming is demonstrated experimentally. 相似文献
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A. Piccardi M. Trotta M. Kwasny A. Alberucci R. Asquini M. Karpierz A. D’Alessandro G. Assanto 《Applied physics. B, Lasers and optics》2011,104(4):805-811
We investigate the propagation of nematicons in various nematic liquid crystals. Following some general considerations on
the role of material parameters in light self-trapping via a reorientational nonlinear response, we discuss numerical results
on light self-action and transverse localization. Finally, we validate our findings with experimental measurements in three
liquid crystalline mixtures featuring different amounts of birefringence. 相似文献