整体快速擦除式激光选址液晶光阀

本文介绍一种改进的激光选址液晶光阀。它以液晶的光散射态(暗态)为显示背景,减少了对观察者眼睛的刺激;它的整体擦除时间大约0.5～1s.采用以暗态为背景的方案,必须对光阀施加高电压才能进行整体擦除,高电压容易使光阀击穿。本文采用在导电层与吸收层之间镀隔离层,就可避免因加大液晶层厚度使写入光灵敏度降低,又增加了高电压与大电流的承受能力。     

非晶硅液晶光阀

本文介绍反射式非晶硅液晶光阀的研制方法，并对其光电性能进行了研究，提出非晶硅液晶光阀的参数设计模型。     

紫外透射型液晶光阀用ZnSxSe1-x薄膜的研究

描述了透射型ZnS,Se1-x光盲紫外液晶光阀的结构和工作原理,并从器件的电学模型出发,着重讨论了整体器件对ZnSxSe1-,光敏层的特殊要求.采用分子束外延技术在ITO石英导电玻璃上制备了不同组分的三元ZnS,Se1-x多晶薄膜,通过控制反应时的生长参数,制备出了符合器件设计要求的光敏层薄膜.室温下,薄膜 的紫外/可见光响应对比度大于103,响应波长截止边可通过控制薄膜中的Se组分,在360～410nm范围内连续可调;薄膜的紫外/可见光吸收系数比大于103;在液晶光阀工作的低频段(＜200Hz),其暗阻抗在105～106Ωcm2之间;暗/亮阻抗比满足器件要求.     

单液晶光阀彩色大屏幕投影显示

设计一电路,将彩色图象信息编码到黑白CRT的亮度之中,并将其写入液晶光阀,用白光读出,当编码合适时,读出的象颜色可与原图像一致。本文讨论了这一技术原理并进行了单液晶光阀彩色大屏幕投影的实验验证。     

光寻址液晶光阀的吸收层

光寻址液晶光阀是一种高分辨率空间光调制器，是高亮度，高分辨率大屏幕光寻址液晶光阀投影机的核心部件，为了避免读出光对图像对比度和分辨率的影响，光阀结构中需要一层高光吸收能力的吸收层。本讨论了光寻址液晶光阀对光吸收层的吸收性能要求，吸收层需求在全光谱范围内都有比较强的吸收，碲化镉薄膜对蓝，绿光有较强的吸收，钒氧配套红光具有较强的吸收，它们具有近似互补的吸收光谱。碲化镉和钒氧酞菁复合多层吸收薄膜综合了两种材料的光吸收特性，在全光谱范围内都有良好的吸收，是一种制作光寻址液晶光阀的吸收层的理想方法。     

液晶光阀阻光层研究

本文研究了阻光层在液晶光阀中的作用，报导了我们首先提出的ｎｃ－Ｓｉ：Ｈ作为液晶光阀阻光层。ａ－Ｓｉ：Ｈ光导层和ｎｃ－Ｓｉ：Ｈ阻光层通过辉光放电等离子体化学气相沉积法连续制得。本文研究了不同沉积条件下ｎｃ－Ｓｉ：Ｈ薄膜结构和光电性质。ａ－Ｓｉ：Ｈ和随这沉积的ｎｃ－Ｓｉ：Ｈ形成了ａ－Ｓｉ：Ｈ／ｎｃ－Ｓｉ：Ｈ异质结。采用ａ－Ｓｉ：Ｈ／ｎｃ－Ｓｉ：Ｈ异质结构液昌光阀可改进器件的许多性能。     

紫外透射型液晶光阈用ZnSxSe1—x薄膜的研究

描述了透射型ZnSxSe1-x光盲紫外液晶光阀的结构和工作原理，并从器件的电学模型出发，着重讨论了整体器件对ZnSxSe1-x光敏层的特殊要求，采用分子束外延技术在ITO石英导电玻璃上制备了不同组分的三元ZnSxSe1-x多晶薄膜，通过控制反应时的生长参数，制备出了符合器件设计要求的光敏层薄膜，室温下，薄膜的紫外／可见光响应对比度大于10^3，响应波长截止边河可通过控制薄膜中的Se组分，在360－410nm范围内连续可调，薄膜的紫外／可见光吸收系数比大于10^3，在液晶光阀工作的低频段（＜200Hz)，其暗阻抗在10^5-10^6Ωcm^2之间；暗／亮阻抗比满足器件要求。     

利用液晶光阀实现的Joint变换

本文叙述了Joint变换的基本原理,并利用液晶光阀的偏振调制特性实现了Joint变换,液晶光阀作为实时记录器件,可以对物体的频谱进行改善,从而得到了较好的相关输出,实验结果与理论分析相符,提供了实时光学相关的一种新方法。     

液晶光阀中的α-Si:H光导膜研究

本文对在光学信息处理中应用的液晶光阀的关键性膜层——光电导膜采用新近开发的非晶硅材料作了一些探索。研究表明,响应快速的α-Si:H薄膜用于液晶光阀是很有前途的。     

分子束外延生长液晶光阀用ZnSxSe1-x薄膜的研究

描述了ZnSxSe1-x光盲紫外液晶光阀的结构和工作原理 ,并从器件的电学模型出发 ,着重讨论了整体器件对ZnSxSe1-x光敏层的特殊要求。采用分子束外延技术在ITO导电玻璃上制备了具有 (111)面定向生长结构的ZnSxSe1-x多晶薄膜 ,通过控制反应时的生长参数 ,制备出了符合器件设计要求的光敏层薄膜。室温下 ,该薄膜的紫外 /可见光响应对比度大于10 3 ;响应波长截止边可通过控制薄膜中的Se组分 ,在 (36 0～ 4 10 )nm范围内连续可调 ;薄膜的暗电阻率在 (4 32× 10 9～ 2 0 3×10 11)Ω·m之间 ,并随着晶粒的增大而减小 ;在液晶光阀工作的低频段 (<2 0 0Hz) ,其光 /暗阻抗比在 0 2 2～ 0 36之间。     

Bistable salt doped cholesteric liquid crystals light shutter

Liquid crystals have been used to make electrically switchable light shutters (windows), but most of them are monostable: opaque in the absence of applied voltage and transparent when a voltage is applied. Here we report a bistable switchable light shutter based on cholesteric liquid crystal doped with tetrabutylammonium bromide. The salt makes it possible for the liquid crystal to have different electro-optical responses to applied voltages with different frequencies. The shutter can be either transparent or opaque in the absence of applied voltage. It can be switched from the transparent state to the opaque state by applying a low frequency (60 Hz) voltage pulse and switched back to the transparent state by applying a high frequency (2 kHz) voltage pulse. Because of the bistability, it can be used for energy-saving switchable privacy control and architectural windows.     

用ARS法分析光纤面板表面粗糙分布

使用光散射空间分布自动测量系统对液晶光阀大屏幕投影系统中使用的光纤面板的表面在入射平面内的微分散射分布进行了测量，该系统的测量灵灵敏度优于１０，线性动态范围达６０ｄＢ，使用角负分布散射方法分析了光纤面板的表面粗糙分布特性及其对象质可能造成的影响。     

快速响应光阀的制备及在真三维立体显示中的应用

固态体积式真三维立体显示系统主要由数据传输,图像处理模块,高速彩色投影光路模块,显示模块(显示体)以及外围控制电路组成。显示模块由多层液晶光阀组成,光线透过显示体后能量衰减严重,造成显示画面黯淡,模糊,此外,由于光阀响应时间慢,系统刷新频率低,屏幕存在严重的闪烁问题。本文通过在液晶中添加少量聚合物和手性物添加剂制备出快速响应的聚合物稳定胆甾相液晶光阀,其开态透过率达到88%,响应时间小于1ms。将其应用于真三维立体显示系统,显示画面清晰稳定,无闪烁。     

聚合物结构对聚合物网络稳定液晶薄膜电光性能的影响

用带有联苯结构的双丙烯酸酯和单丙烯酸酯作为单体,采用紫外光引发聚合诱导相分离法制备了聚合物网络稳定液晶(PSLC)薄膜。研究了不同液晶含量、固化时间、单体结构、取向层对PSLC膜电光性能的影响。结果表明,随着液晶含量的增加,样品的关态透光率(TOFF)随之增大,驱动电压则呈减小趋势;相对而言,随固化时间的增加,样品的TOFF则降低。在PI作取向层时,由双丙烯酸酯单体制备的样品表现出了较高的TOFF,而由单丙烯酸酯单体制得的样品,因其聚合物网络结构的不稳定性,在较低电压情况下就出现了"变形"的电光曲线。     

采用液晶光阀的氦氖激光准直控制

激光光束的漂移,功率稳定性和激光光斑的强度分布对称性是影响准直精度的主要参数。通过分析液晶光阀的特性,提出了一种智能型光束准直控制方法,可同时控制激光功率的稳定性和光斑的强度分布对称性。利用热平衡技术,设计了一套温度实时反馈控制的准直装置。实验结果证实了该方法的可行性和有效性。     

Optical reconfiguration by anisotropic diffraction in holographic polymer-dispersed liquid crystal memory

Holographic polymer dispersed liquid crystal (HPDLC) memory is fabricated by a photoinduced phase separation comprised of polymer and liquid crystal (LC) phases using laser light interference exposures. The anisotropic diffraction induced by the alignment of LC in the periodic structure of the HPDLC memory is applied to reconstruct the configuration contexts for the optically reconfigurable gate arrays. Optical reconfiguration for various circuits under parallel programmability is implemented by switching the polarization state of incident light on the HPDLC memory using a spatial light modulator.     

Polarization-independent optical fiber modulator by use of polymer-dispersed liquid crystals

Ultrasmall light modulators have been made by sandwiching a polymer-dispersed liquid crystal (PDLC) between two ferrules with optical fibers. The device can modulate light independent of the state of polarization, because the PDLC becomes transparent or opaque when either sufficient or no voltage is applied to the film. The PDLC was prepared by mixing and annealing a prepolymer and nematic liquid crystal with large anisotropy. An optical fiber modulator with a 30-mum thick PDLC film had an extinction ratio of 8:1-33:1, an insertion loss of 1.3 dB, and rise and decay times of 4 ms at a wavelength of 1.3 mum.     

Light-induced transmission changes in liquid crystal displays foradaptive pattern projection

The changes in the transmission and contrast properties of a super-twisted nematic liquid crystal display panel, induced by the light impinging on the panel itself, have been studied. Upon illumination by laser radiation with power density close to that used in practice, the transmittance of the panel increases or decreases according to the brightness voltage that sets the transmittance level. The dynamics of the transmittance change are typically bi-exponential, with a shorter decay time on the order of a fraction of a second and a longer decay on the order of tens of seconds. The observed changes were interpreted and modeled by considering local temperature changes in the crystal because of the light impinging on it. The temperature changes produce a shift of the transmittance curve and a change of slope in its central region. The presence of the dip after the Frederickzs region accounts for the anomalous behavior of the transmittance in that portion of brightness voltages     

Fast, automatically darkening welding filter offering an improved level of safety

A mode of operation is introduced for the standard 90° twisted nematic (TN) liquid-crystal cell when placed together with an interference filter and positioned between crossed polarizers such that a small stimulating voltage of between ±2.0 and ±13.0 V is required in order to attain the light state. Further incrementation of the driving electronics reverts the system back to a darker phase. Such cells offer advantages over those of the standard 90° TN device operating in the normally white mode, in that the unit maintains the fast response time from the light to the dark state associated with the employment of TN cells placed between crossed polarizers. In addition, a low transmittance state is achieved when the unit is in the inactivated phase; this is an effect usually correlated with the normally black mode of operation. These cells are therefore ideal candidates for incorporation into fast, automatically darkening, welding filters that are designed to change rapidly from the light to the dark protective state, while offering an improved level of safety by not holding in a potentially hazardous light state should the controlling electronics malfunction. The requirement for this phenomenon to be observed is that the cell displays a low optical transmittance over the green wavelengths of the visible spectrum when in the inactivated phase and placed between crossed polarizers. The presence of an interference filter that possesses a peak transmittance over the central part of the visible spectrum is also necessary. It is shown that there are only two possible cell types that satisfy this criteria, and the optical properties of such cells are analyzed in some detail.     

Absolute measurement of the generated aberrations from liquid crystal spatial light modulator using a common-path interferometry

A compact common-path interferometry is proposed to measure the wavefront aberration generated from liquid crystal spatial light modulator (LC-SLM). The LC-SLM is encoded with an aberration pattern and illuminated with a linearly polarized light oriented at ±45° with respect to the fast axis of liquid crystal, which is vertically oriented. The horizontal polarization component of the incident beam is not affected by the driving signal, while the vertical polarization component is modulated to the aberration loaded to the LC-SLM. By imposing a quarter-wave plate and a rotating analyzer, these two waves create four frames of phase-stepped interferograms. The aberration to be measured can be retrieved, and the result does not include any systematic error such as the substrate error of LC-SLM. Therefore, this method can implement absolute measurement, and help us to evaluate perfectly the fitting accuracy of the LC-SLM.