温度梯度制备宽波反射液晶薄膜

合成了大螺旋扭曲力的手性化合物4,4′-2(戊基-环己基)苯甲酸异山梨醇酯(ISBB)。对60.0μm厚ISBB/液晶性单体/向列相液晶/光引发剂复合体系的液晶层的上、下表面温度施加不同温度,液晶层中形成了温度梯度。由于高温区域的液晶溶解ISBB的能力强,低温区域的ISBB会向高温区域扩散,从而在液晶薄层中形成了ISBB的浓度梯度与螺距梯度。紫外光聚合复合体系中的光可聚合单体,单体间交联聚合形成网络固定住了液晶层内的螺距梯度,从而制备出反射可见光波段的右旋圆偏振光的宽波反射液晶薄膜。     

多彩液晶微胶囊的制备及性能研究

采用手性剂掺杂向列相混合液晶制备出具备类似胆甾相液晶温变显色性能的液晶混合物。通过控制向列相液晶中手性剂的添加量,调节混合液晶的颜色,制备出系列室温下呈颜色转变的液晶混合物。在此基础上,探究3种不同添加剂对混合液晶显色性能的影响,确定具备最佳温变显色性能的液晶混合物配方。以上述液晶混合物为芯材、异佛尔酮二异氰酸酯(IPDI)为壁材,采用界面聚合法在不同反应条件下制备出一系列液晶微胶囊,并确定最佳反应条件。结果表明:最佳反应条件下,制备的液晶微胶囊粒径范围在50～105μm之间,平均粒径在68.06μm左右,囊芯材料含量约占35%。液晶微胶囊呈规则球形,粒径比较均匀,具有良好的温变显色性能,且热稳定性较高,热分解温度达330℃以上。     

光学双向反射分布函数的测量装置研究

介绍了双向反射分布函数的测量原理和方法,搭建了双向反射分布函数的测量装置。该装置可以测量可见光和红外两个波段的双向反射分布函数。在可见光波段采用卤钨灯作为光源,采用光纤光谱仪作为光接收器,以10 nm的波长间隔测量双向反射分布函数。在红外波段采用碳化硅作为红外光源,采用热释电探测器作为光接收器,采用标准板相对定标的方法测量待测样板的双向反射分布函数。可见光波段双向反射分布函数的测量重复性不大于1.5%;3μm~5μm红外波段双向反射分布函数的测量重复性分别小于或等于2.5%、8μm~12μm波段的小于或等于3.0%。测量结果表明,该测量装置的有效性较高。     

超声对纤维素纳米晶体的溶致胆甾相液晶的影响

通过偏光显微镜法、紫外-可见光光谱学、XRD和电导率分析方法研究了大功率超声对纤维素纳米晶体(CNC)的溶致胆甾相液晶(N*-LC)螺距的影响及其在干燥状态下所制得薄膜的光学性能。研究结果表明,溶致N*-LC的螺距随着超声功率的增大而增大,其干燥薄膜的反射波波长红移,且红移幅度与超声功率有关。但是,CNC的晶型和尺寸没有明显变化。电导率测试结果表明,超声处理使溶致N*-LC的电导率提高。由此推测溶致N*-LC的螺距增大的主要原因是大功率超声处理使束缚在双电层中的带电离子释放出来,进而CNC粒子之间的静电斥力变大所致。     

聚合物分散液晶薄膜中随机激光辐射的实现

设计制作染料掺杂聚合物分散液晶薄膜激光器件,研究随机激光辐射行为。利用微胶囊法将激光染料、向列相液晶、手性剂、聚乙烯醇混合,制备掺杂两种激光染料的聚合物分散液晶薄膜。利用输出激光532 nm的Nd:YAG倍频脉冲激光器进行泵浦,在582～607 nm波段获得尖锐、离散的随机激光输出,阈值能量约为9 mJ,线宽约为0.3～0.4 nm。对于器件产生激光辐射的机制,利用环形腔理论进行了分析。对比掺杂单种激光染料的聚合物分散液晶薄膜激光器件,实验结果显示,同时混合不同类型的激光染料制备的聚合物分散液晶薄膜,能够实现较宽波段的随机激光输出。     

非直流电压对N*-SmC*相序铁电液晶排列的影响

半"V"字形铁电液晶器件中使用N* -SmC*相序的铁电液晶材料,获得此种器件单畴排列的常用方法是在N*-SmC*相变过程中施加直流电压,但是这种方法引入了损害器件性能的剩余电荷.通过研究在相变过程中施加各种非直流电压对液晶排列织构的影响,发现直流电压不是得到N*-SmC*相序的铁电液晶均一排列的必要条件,通过选择双极性电压为V1=7V/μm,V2=3 V/μm,一个脉冲周期20 ms内施加双极性电场时间比为D1/D2=3/7,不仅获得了电光特性曲线不存在迟滞回线的均一层排列器件,同时也解决了剩余电荷对器件的影响.     

高温超导红外测辐射热计

根据超导测辐射热计的理论，以YBCO为材料，制备的高温超导薄膜型红外测辐射热计，黑体响应度Rv＞104V／W，D*＞1010cmHz1／2W－1，NEP≈10－14WHz-1／2。测量和分析了器件的频率响应、噪声特性和其对1～15μm波段及118．8μm，337μm，570．5μm，699μm，1009．4μm等波长的光谱响应。测量结果表明，高温超导红外测辐射热计对整个红外波谱都有响应，但其性能在远红外波段衰减很厉害，因此，对器件的表面处理应是提高其长波性能的一个关键。     

离子束溅射氧化物薄膜的中红外特性

以离子束溅射沉积(IBSD)方法制备了Al2O3、Nb2O5单层膜,用红外可变角度光谱椭圆偏振仪(IR-VASE)测试了薄膜的光学常数。用原子力显微镜(AFM)测量了单层膜的表面形貌及表面粗糙度,计算了单个表面的总积分散射(TIS)。以Nb2O5和Al2O3为高低折射率材料设计并制备了2.7μm高反射膜。最后对单层膜进行了环境实验检测。结果表明,制备的薄膜在中红外波段具有高的折射率和低的消光系数,光滑的表面特性和极低的表面散射损耗;在2.7μm波段没有发现由于水吸收导致的消光系数的增大;制备的反射膜在2.7μm反射率达到了99.63%,接近于理论计算值。薄膜顺利通过了一系列环境实验,显示其优良的环境稳定性。     

平面反射镜光学薄膜的制备

以薄膜原理为基础,通过Essential Macleod软件进行膜系设计.采用电子束加热蒸发的镀膜方式,利用设计工装制备了介质ZrO2-SiO2高反射膜层和金属铝反射膜层.介质高反膜层在1.064μm波长处的反射率达到95%,金属铝反射膜层的在3μm～5μm波段内的平均反射率超过95%.膜层的技术指标和环境适应性能具有优质的质量.     

改性蓝蒽酮溶致液晶的偏振性能研究

采用氯磺酸磺化对蓝蒽酮进行改性处理，其水溶液在一定浓度下出现了溶致液晶相，织构呈带状和条状分布。无水乙醇改善了溶致液晶的涂布性能，它是黏稠溶致液晶涂布湿膜时一种良好的添加剂。试验结果表明，厚度为1～1．5μm磺化蓝蒽酮剪切固态薄膜是一种良好的偏光材料。     

Reflective spectrum broadened by nano-particle-network in chiral liquid crystals

Based on the analytical expression of the electromagnetic field solution of a helical symmetric dielectric material, the relationship between spectral reflectivity and birefringence of a chiral liquid crystal and the blue shift of the Bragg reflection in the condition of oblique incidence are presented in this paper. The theoretical results indicated that: 1) If birefringence (An)of the liquid crystal is greater than 0.2 and the thickness of the liquid crystal layer reaches 3μm, the liquid crystal layer will reflect more than 90% of the incident light; 2)To reflect the whole visible spectrum by Bragg reflection,An of the liquid crystals in plane alignment state should exceed 0.6; 3) When the incident beam inclines to 60°from the normal direction, the blue shift of the reflective spectrum will reach to 100 nm. On the other hand, since the An of the commercial chiral liquid crystals is not larger than 0.2, to get the entire visible reflective spectrum, it needs to introduce a polymer network into the liquid crystals and make a sagging structure on the surface of substrates. The contribution of the network is to establish random anchorage that makes the pitch varied, hence broadening the Bragg reflection spectra.The random distribution of the sagging structure on the surface substrate is used to induce random screw axes of the chiral liquid crystal, which not only causes a blue shift of Bragg reflection but also further stretches the reflection spectra. Experiments demonstrated that the Bragg reflection spectrum could be broadened from by introducing both polymer network and sagging structure on the substrate surface cell.     

Liquid-crystal light deflector

It is shown experimentally that the cell with an n-type nematic liquid crystal may have two functions, light deflection and shutter, and that the cell with a reflective coating film may deflect a light beam about twice the angle achieved with a transmission type of cell.     

Dye-doped photorefractive liquid crystals for dynamic and storageholographic grating formation and spatial light modulation

The basic mechanisms of photo-induced space charge field formation, director axis re-orientation, and refractive index changes in fullerene C60- and dye-doped nematic liquid crystals films are presented. In particular, in aligned methyl-red-doped nematic liquid crystal film, we observe a nonlinear index change coefficient as high as 10 cm²/W, associated with purely optically induced liquid crystal director axis re-orientation. Experimental observations of dynamic and high-resolution storage holographic grating formation, two beam coupling with gain of nearly 3000 cm^-1, optical limiting action at nanowatt cw laser power, and incoherent-coherent image conversion at μW/cm² light intensity level are discussed     

用全漏光导波技术测量反射式混合型扭曲向列相液晶盒的指向矢分布

架设了全漏光导波测量系统并对反射式混合型扭曲向列相液晶盒进行了光学测量,氦氖激光经过处理后变为s偏振光或p偏振光,然后通过棱镜耦合使某一偏振状态的光进入液晶盒并采集不同电压下与入射角相关的不同偏振光组合的反射信号。进而结合多层光学4×4矩阵和弹性连续体理论对液晶盒的不同状态组合的反射信号模拟预测并与实验数据进行拟合,就得到了指向矢在液晶盒内的倾角和扭曲角以及在不同电压下的分布情况。     

一种光学状态可由电场控制的液晶复合材料的制备与表征

液晶材料对电、热、磁、光等外界物理量的变化具有不同的响应特性,向其中添加具有一定特性的化合物,可以得到具备一定响应特性的液晶复合材料。利用所制备的液晶复合材料对于电场变化具有响应特性的特点,制备出具有信息记录功能的复合材料。合成手性离子液体,按一定配比将其加入手征向列相液晶(N~*-LC)中,得到反射波段可电控的手征向列相液晶/手性离子液体复合材料。实验结果表明:材料初始状态为光透射状态;对材料施加直流电压40V时,样品表现为光散射状态,透过率低于10%;施加高频交流电压40V时,样品表现为半透明镜面反射,反射范围覆盖400～750nm,透射率为45%左右;撤去电场后,可恢复至初始状态,并且每种状态都具有一定的记忆效应。该种液晶复合材料制备简单,无需紫外辐射工艺,且具有电场响应特性,可以通过电场控制在可见光范围内表现出光透射、强烈光散射、半透明镜面反射3种不同状态,具有记忆效应,操作简单方便。     

Chiroptical Resolution and Thermal Switching of Chirality in Conjugated Polymer Luminescence via Selective Reflection using a Double‐Layered Cell of Chiral Nematic Liquid Crystal

An optically resolvable and thermally chiral‐switchable device for circularly polarized luminescence (CPL) is first constructed using a light‐emitting conjugated polymer film and a double‐layered chiral nematic liquid crystal (N*‐LC) cell. The double‐layered N*‐LC cell with opposite handedness at each layer is fabricated by adding each of two types of N*‐LCs into each of the cells, and the N*‐LCs consist of nematic LCs and chiral dopants with opposite chirality and different mole concentrations. The selective reflection band due to the N*‐LC is thermally shifted so that the band wavelength is close to the luminescence band of the racemic conjugated polymer, such as disubstituted polyacetylene (diPA), yielding CPL with opposite handedness and high dissymmetry factor values (|g_lum|) of 1.1–1.6 at low and high temperatures. The double‐layered N*‐LC cell bearing the temperature‐controlled selective reflection is useful for generating CPLs from racemic fluorescent materials and for allowing thermal chirality‐switching in CPLs, which present new possibilities for optoelectronic and photochemical applications.     

Analytic solution of film compensated bistable twisted nematic liquid crystal displays

In this paper, we studied the optics of transmissive bistable nematic liquid crystal displays by using the Poincare sphere approach. We derived analytical solutions of the polarization state of the outcoming light for the two bistable states. We have found the optimum modes of film compensated bistable twisted nematic liquid crystal displays. Our results show that the number of optimized modes at a fixed wavelength of film-compensated bistable twisted nematic (BTN) is infinite. We identified the optimized modes for displays operated in the whole visible light wavelength region. We calculated the transmission spectra of the two bistable states of the optimized modes.     

Large Area Self‐Assembly of Nematic Liquid‐Crystal‐Functionalized Gold Nanorods

Fascinating nematic‐ and smectic‐like self‐assembled arrays are observed for gold nanorods partially capped with either laterally or terminally attached nematic liquid crystals upon slow evaporation of an organic solvent on TEM grids. These arrays can be manipulated and reoriented by applying an external magnetic field from quasi‐planar to vertical similar to a Fréedericksz transition of common organic nematic liquid crystals. Birefringence and thin film textures of these self‐assembled gold nanorod arrays observed by polarized optical microscopy are strongly reminiscent of common organic nematic liquid crystal textures between crossed polarizers and, additionally, support the formation of ordered liquid crystal‐like anisotropic superstructures. The ordering within these arrays is also confirmed in bulk samples using small angle X‐ray scattering (SAXS).     

一种新型光敏小分子用于光控取向的研究

通过在3,5-二羟基苯甲醇分子中的双酚基基团上引入双肉桂酰酯光敏基团的酯化反应,合成了一类新型的分子顶部为羟基极性基团,整个分子构型类似于树枝状的光敏小分子化合物。将此种光敏材料配成一定浓度的溶液,旋涂在玻璃基板上成膜,经过线性偏振紫外光辐照后发生交联反应,制备成光控取向膜。以此种取向膜制成向列相液晶的平行液晶器件,在偏光显微镜下观察,发现取得了均一、稳定的取向效果,并且该取向膜具有良好的热稳定性能。