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利用微机建立了液晶电光效应的控制和探测系统,该系统不仅可以实时、精确、细致地演示和探测液晶的电控双折射效应,而且可以用来研究液晶对外加电压的瞬态响应特性参数。文中提供了液晶光阀在不同波形的驱动电压下的测试结果。 相似文献
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频率驱动液晶光阀的电光特性研究 总被引:4,自引:1,他引:3
讨论了液晶光阀频率驱动方式的原理, 并分析了液晶光阀在频率驱动方式下的电光特性。在特定的交流电压下改变外加电场频率, 测量了TB3639型液晶光阀在频率驱动方式下的电光特性关系曲线。测量结果表明,TB3639液晶光阀在可见光区域具有电光显示灰度变化特性,不仅能实现黑白显示,也能实现不同灰度级显示。频率驱动方式在可见光的范围内对不同波长的透射率变化趋势影响大致相同,在应用中可避免出现色差较大的现象。这种新型频率驱动方式对液晶器件的显示有改善作用,将开拓液晶显示器件的新应用, 具有实际应用价值。 相似文献
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提出了一种高性能液晶透镜的设计方法。该方法结合了电极结构的设计并利用了液晶材料线性响应区。所设计的电极结构用于产生抛物线的电压分布,将驱动电压控制在液晶材料的线性响应区内可以实现抛物线的相位分布。通过该方法设计的液晶透镜,其孔径可以是任意大小,且不依赖高阻膜。所设计的电极结构简单,加工只需要一次光刻。透镜由两个低电压驱动,驱动方法简单,其焦距可通过两个驱动电压进行调节。理论上这种液晶透镜的相位分布在变焦过程中保持理想的抛物线分布,且光焦度正比于两个驱动电压的差值。实验上,通过光刻法加工了所设计的电极结构,测量了液晶材料的线性响应区,制作了液晶层厚度为50μm的液晶透镜。通过偏振干涉原理采集了干涉条纹,并从中提取了相位信息。实验结果表明,透镜的相位服从抛物线分布,且光焦度与驱动电压的差值成正比。实验结果与理论分析一致。 相似文献
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针对氢化非晶硅/铝/铁电液晶结构的光寻址空间光调制器(OASLM),依据其等效电路模型,利用Pspice和Matlab软件对其分辨率、响应速度、对比度及灰度响应等性能进行了分析。结果表明:在铁电液晶(FLC)层厚度一定的情况下,减小光敏感层(a-Si:H层)的厚度可以提高FLC-OASLM的调制传递函数,从而提高分辨率;在其他参量一定的情况下,FLC-OASLM的响应速度随写入光光强增大而增大(写入光从0.08 mW/cm2增大到10 mW/cm2,延迟时间减小110 s,上升时间减小154 s),随擦除光光强增大而减小(擦除光从0增大到1 mW/cm2,延迟时间增大41 s,上升时间仅增加3 s);FLC-OASLM的对比度随控制光光强增大而增大,最终趋于一个稳定值21∶1;在其他参量不变时,随着擦除光光强的增大,输出光响应呈现等级下降,且发现当擦除光光强达到一定值(3 mW/cm2)后,擦除光的改变主要影响下降时间而对上升时间几乎无影响;合理设计激励源信号波形,可以得到超过十级灰度输出,表明擦除光具有实现FLC OASLM的灰度响应的功能。 相似文献
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液晶空间光调制器相位调制测量及波前校正 总被引:3,自引:1,他引:2
提供了一种简单且精度较好的测量液晶空间光调制器相位调制特性的方法,即相位与电压(灰度)之间的关系。采用数字波面移相干涉仪,由干涉仪直接给出不同灰度对应的相位差,从而得到液晶空间光调制器的相位调制曲线。利用液晶空间光调制器实现了波前校正。由干涉仪作波前测试,对待校正的畸变波前进行泽尼克多项式描述,根据液晶空间光调制器的相位与灰度的关系,产生相应的灰度图,获得畸变波前的共轭波前,从而完成静态波前的校正,使相关参数如PV值、RMS值和Strehl比值得到了改善。 相似文献
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液晶响应时间是描述液晶显示器性能的重要参数,研究驱动电压对液晶响应时间的影响对确定液晶显示器最佳工作电压具有重要意义。本研究通过理论分析确定了强、弱锚定条件下指向矢上升和下降时间的计算方程,根据电光效应曲线确定了驱动电压选取范围,分析了驱动电压范围内的响应时间变化规律。结果表明:对于本研究所采用的液晶,响应时间随驱动电压的增加呈现先增大后减小的特征,拐点在3 V左右;随着驱动电压的增加,下降时间具有驱动电压成反比的特点,而上升时间则呈现明显的分段特征,驱动电压在2~2.5 V的范围,上升时间几乎不变,驱动电压在2.5~5 V的范围,上升时间增加;结合液晶分子在驱动电压作用下的动力学响应过程,通过强、弱锚定条件下指向矢上升时间和下降时间的计算方程进行模拟可以解释上升时间呈现分段特征的原因。 相似文献
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提出在电压驱动下液体透镜的响应包括固有响应和强制响应,固有响应信号的函数形式由液体透镜的各种参数决定,与驱动电压无关,但其系数与驱动电压有关,强制响应与驱动电压具有相同的函数形式,液体透镜暂态过程的变化规律取决于固有响应,同样与驱动电压无关。因此,对同一液体透镜改变驱动电压仅改变暂态过程的响应幅度,不改变暂态过程的变化规律,从而也不改变液体透镜的响应时间。实验验证了液体透镜的响应可分解为固有响应和强制响应,测量了不同电压驱动下液体透镜的响应过程及响应时间,并对测试结果进行了理论分析。另外,观察到电润湿液体透镜的反冲现象,该现象出现在加载电压和撤去电压的初始阶段。 相似文献
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MOLECULAR ORIENTATION AND COLOR ALTERNATION OF SURFACE STABILIZED FERROELECTRIC LIQUID CRYSTAL CELL 下载免费PDF全文
Molecular orientation configurations across zig-zag defects and thin-line defects of the surface stabilized ferroelectric liquid crystal (SSFLC) cell are presented. The transmission spectra of the SSFLC cell of non-uniform states are numerically calculated using the asym-metric chcvron structure model. The calculations agree well with experimental results, which confirms the continuity of the N-director across the chevron interface. The color alternation of the SSFLC cell between crossed polarizers is well explained. 相似文献
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We propose a strategy for a micromanipulation method using SSFLC (surface stabilized ferroelectric liquid crystals). By adjusting the frequency of the applied ac electric field, the surface layers that cannot follow an applied ac electric field are constructed in SSFLC. In addition, by applying a sawtooth wave voltage, net flow along the smectic layer is generated. The flow direction is reversed by changing the polarity of the sawtooth wave. Consequently, the particles dispersed in SSFLC can be driven bidirectionally along the smectic layer. The particle velocity depends on the temperature, amplitude, and frequency of the applied voltage. 相似文献
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An analysis of consistency of dielectric and optical response methods is carried out for surface stabilized ferroelectric
liquid crystals (SSFLC) with chevron geometry. The consistency is found both theoretically and experimentally for weak external
electric fields of intermediate frequencies, for which the response of SSFLC is dominated by collective relaxation processes
due to azimuthal reorientation of molecules arranging chevron layers. The methods are experimentally shown to lack consistency
within very low, relatively low, and high field-frequency ranges. The disagreement appearing at relatively low frequencies
is argued to be a consequence of different recording by dielectric and optical techniques the dynamics of zig-zag walls, forming
defects in chevron structure. 相似文献
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G. Padeletti S. Pergolini G. Montesperelli A. D’Alessandro F. Campoli P. Maltese 《Applied Physics A: Materials Science & Processing》2000,71(5):571-576
Atomic force microscopy (AFM) has become a powerful technique for submicron investigation of surface properties. In this work
we use the capability of this technique to investigate dielectric films used to align ferroelectric liquid crystals (FLC).
In fact, the final performance of a surface stabilized FLC (SSFLC) flat panel display strongly depends on the alignment layer
properties and quality. This work focuses on a comparison of two alignment films: the more conventional polyamide, nylon 6,
and polytetrafluoroethilene (PTFE, commercially known as Teflon), only recently used as a new aligning material.
A micromorphological characterization of the sample surfaces has been carried out in order to correlate structure with alignment
properties of both polymer films. The results show varying roughness and periodicity wavelengths for the two alignment layers.
These different properties can be related to different anchoring forces between aligning surfaces and FLC molecules and therefore
to a different electrooptical response of SSFLC cells. In addition to the topographic characterization, AFM non-conventional
measurements have been performed on alignment layers deposited on different transparent conductive oxides, such as indium
tin oxide (ITO) and SnO2, used to make electrodes in SSFLC displays. These measurements provide local information on the adhesive properties of the
studied alignment materials as a function of substrate coating. These observations indicate less adhesion of PTFE with respect
to nylon 6.
Received: 16 April 2000 / Accepted: 16 April 2000 / Published online: 13 September 2000 相似文献
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Electro-optical properties and(E,F) phase diagram of fluorinated chiral smectic liquid crystals 下载免费PDF全文
Fluorinated smectic liquid crystals each with a biphenyl benzoate rigid core are investigated. Molecular structures of the studied compounds have difference only in fluorine position and the length of the carbon chain. Dielectric relaxation study and electro-optical measurements are carried out with the classical SSFLC geometry. The field-induced phase transitions are studied and the(E,T) phase diagram is established. 相似文献
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Generalized Theory of One-Dimensional Steady-State Optical Spatial Solitons 总被引:1,自引:0,他引:1 下载免费PDF全文
We present a generalized soliton theory based on the one-dimensional generalized nonlinear Schroedinger equation,from which one can easily obtain the bright, dark, and grey soliton waveforms, and their existence curves. We show that the forming conditions of spatial solitons are directly dependent on the relationship between the index perturbation and the intensity, no matter whether the index perturbation is positive or negative. Some relevant examples are presented when the solitons are supported by the photoisomerization nonlinearity. 相似文献
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We present the operational principles and results of a temporal imaging system, configured as a time microscope, that achieves 103 x magnification of waveforms with 300-fs resolution and a 5.7-ps field of view. The quadratic-phase time-lens element is realized by upconversion of the dispersed input waveform with a linearly chirped 5-THz bandwidth pump. The system allows expansion of ultrafast optical waveforms to a time scale that is directly accessible with slower conventional technology, in real time, on a single-shot basis. 相似文献
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M. A. Geday D. P. Medialdea B. Cerrolaza N. Bennis X. Quintana J. M. Otón 《Opto-Electronics Review》2009,17(2):140-143
The ferroelectric-antiferroelectric transition in greyscale generation of antiferroelectric liquid crystal displays (AFLC)
is a heterogeneous process. The process has been described as the growth of finger-like domains [1]. We have previously studied
the ferroelectric-antiferroelectric phase transition, relaxation that follows the data pulse in surface stabilized asymmetric
antiferroelectric liquid crystal displays using biasless video frequency waveforms [2]. This relaxation involves an intensity
decay of the light transmitted by a pixel and depends on several parameters such as surface stabilization, rotational viscosity
of the AFLC, magnitude of the data pulse, and bias voltage.
The usual multiplexed driving of AFLC displays leads to long-term stabilisation of the grey levels induced by the data pulses
within the selection time. However, depending on the bias level, alternative greyscale mechanisms may be obtained by allowing
the grey levels to decay during the frametime. These greyscales may be advantageous in some instances since they improve the
dynamic response of the AFLC device and reduce the reset time of the waveform.
In this study we extend the previous work to include the effect of bias. We present the measured data, in terms of growth
pattern and speed and present an extension of the previously model on order to explain the results. 相似文献
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Ryszard Piasecki 《Physica A》2009,388(12):2403-2409
An entropic measure for the analysis of grey level inhomogeneity (GLI) is proposed as a function of length scale. It allows us to quantify the statistical dissimilarity of the actual macrostate and the maximizing entropy of the reference one. The maximums (minimums) of the measure indicate those scales at which higher (lower) average grey level inhomogeneity appears compared to neighbour scales. Even a deeply hidden statistical grey level periodicity can be detected by the equally distant minimums of the measure. The striking effect of multiple intersecting curves (MICs) of the measure has been revealed for pairs of simulated patterns, which differ in shades of grey or symmetry properties only. In turn, for evolving photosphere granulation patterns, the stability in time of the first peak position has been found. Interestingly, the third peak is dominant at initial steps of the evolution. This indicates a temporary grouping of granules at a length scale that may belong to the mesogranulation phenomenon. This behaviour has similarities with that reported by Consolini, Berrilli et al. [G. Consolini, F. Berrilli, A. Florio, E. Pietropaolo, L.A. Smaldone, Astron. Astrophys. 402 (2003) 1115; F. Berrilli, D. Del Moro, S. Russo, G. Consolini, Th. Straus, Astrophys. J. 632 (2005) 677] for binarized granulation images of a different data set. 相似文献