Mechanisms of optical anisotropy induction in azopolymer films

The process of optical anisotropy indiction in azopolymer films upon irradiation by polarized UV light is studied by means of UV and IR birefringence spectroscopy. A substantial dependence of the character of the relaxation of the induced anisotropy on the exposure time to the exciting light is revealed: whereas the process of anisotropy induction is reversible at small exposure times, at large exposure times the induced anisotropy virtually does not relax and even increases after the irradiation is terminated. A difference between kinetic curves of dichroism and birefringence induction is shown: at exposure times corresponding to the saturation of the induced dichroism a slow increase in the birefringence curve is observed. Results obtained are explained in terms of the assumption of partial ordering of macrochain fragments in irradiated films. The assumption is substantiated by measurements of polarized IR spectra. Institute of Physics of the National Academy of Sciences of Ukraine, 46, Nauka Ave., Kiev, 252650, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 121–125, January–February, 1998.     

Electro-optical properties of polymer stabilized cholesteric liquid crystal film

Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications.In this paper,normal mode polymer stabilized cholesteric LC film is prepared and studied.The effects of chiral dopant and monomer concentrations on the electro-optical properties,such as contrast ratio,driving voltage,hysteresis width and response time,are investigated.The reasons of electro-optical properties influenced by the concentrations of the materials are discussed.Through the proper material recipe,the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.     

Electro-optical properties of doped anthracene films

Electroluminescence in anthracene doped with anthraquinone (10^?3 mole%) films are presented. Films are deposited at room temperature in a vacuum of 10^?5 torr. It is observed that at constant frequency the brightness/voltage relationship follows the relation $\text{B = B}{}_0\text{exp}\text{(?b/V}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}$. The results show that electroluminescent brightness increases linearly with frequency. At lower frequencies green electroluminescent (EL) emission and at higher frequencies blue EL emission is observed. Similar nature for I–V and brightness/voltage relationship are found in anthracene doped with 10^?4 mole% anthraquinone.     

全息聚合物弥散液晶器件电光特性的研究

研究了全息聚合物弥散液晶(HPDLC)器件的电光特性，研究了添加不同表面活性剂对聚合物界面对液晶的锚定能的影响机理，寻求到了低工作电压的实现方法. 分析了聚合物基体与液晶折射率不匹配性对器件对比度的影响，测量了HPDLC器件的响应时间和弛豫时间，得到了平均100μs的快速响应. 关键词： 全息聚合物弥散液晶 电光特性 表面活性剂 对比度 响应时间     

Electro-optical properties of high birefringence liquid crystal compounds with isothiocyanate and naphthyl group

Liquid crystal(LC) compound with isothiocyanate and naphthyl group is an attractive high birefringence LC material,and can be used in optical devices. In this paper, the electro-optical properties of a series of this type of LC compounds were investigated. The melting points and enthalpy values of these LC compounds were higher than those of corresponding compounds with the phenyl group. These compounds exhibited high birefringence with a maximum value of 0.66. Fluorine substitution in the molecular almost does not affect the birefringence value. When these LC compounds with the naphthyl group were dissolved in a commercial LC mixture, the electro-optical properties depending on temperature were investigated. In the low-temperature region, LC mixtures with the naphthyl-group LC compounds exhibited higher viscosity than pure commercial LCs. In the high-temperature region, viscosity values very closely approached each other. When response performance was investigated, figure-of-merit(Fo M) values were measured. The Fo M values of LC mixtures containing LC compounds with naphthyl group were lower than those of reference benzene LCs in the low-temperature region. However, in the high-temperature region, the results were reversed. These isothiocyanate LC compounds with naphthyl group can be applied in special fast-response LC device, particularly the ones used under high-temperature conditions.     

光电干扰与微光夜视

微光夜视与激光器几乎同时应用于战场,并各自得到迅速发展。随着战术技术的不断发展,发现战场上的微光夜视与激光器有某种制约关系。同时,微光夜视还受到其它有源和无源干扰。因此,激光夜视技术面临如何对抗光电干扰,尤其是激光加固的重要课题。     

Electro-optical Kerr effect in the isotropic phase of the two antiferroelectric liquid crystal mixtures

We have experimentally studied for the first time the electro-optical Kerr effect and the pre-transitional behavior in the isotropic phase of two antiferroelectric liquid crystal mixtures, W-232 and W-204D, composed of rod-like ester molecules exhibiting the direct smectic-A to isotropic (SmA-I) phase transition. The Kerr law has been confirmed for the two compounds and the variation of inverse Kerr constant with temperature above the smectic–isotropic transition temperatures were determined. Both the mixtures with very broad antiferroelectric phase around room temperature have similar sequence of the phases (i.e., Cr-SmC*A-SmC*-SmA-I). Although, the pre-transitional behavior is usually complex in the isotropic phase of the chiral smectic liquid crystal compounds, the investigated compounds showed a similar behavior compared to that of nematic–isotropic behavior.     

快速耦合光纤过程与半导体激光器电光特性实验的研究

详细地介绍了怎样快速耦合半导体激光器所发射激光与普通光纤输入端端面的方法,使耦合效率尽可能达到最大,并使用简单的方法测量了光纤的剩余长度或者测量光速,最后给出据测量半导体激光器电光特性曲线可准确方便地获得阈值电流的方法。     

Monte Carlo study on bilayer thin films magnetic properties dependence with discontinouos anisotropy parameters

In the last few years there has been significant interest in the field of thin films, due to numerous specific phenomena related to the low dimension of these systems, and to the large opportunities in development of high technologies based on their specific magnetic and electronic properties. When dealing with systems of reduced dimensionality it is important to take into account the influence of magnetic anisotropies. In this paper we investigate the magnetic properties of bilayer thin film. This behavior is modeled using Monte Carlo simulations, in the Extended Anisotropic Heisenberg Model. The magnetization, out-of-plane and in-plane magnetic susceptibilities, and also the specific heat bearings according to temperature are investigated in order to find the potential magnetic ordering phases and the critical temperatures, for two sets parameter assignments. For quasi-uniform anisotropy parameters of the film we detect the ferromagnetism-paramagnetism transition and then, by changing the model parameters values, we relieve a short range ferromagnetic ordering phase arising from the antiferromagnetic base layer coupling influence and from easy-plane anisotropy discontinuity on the layers interface.      

Galvanomagnetic properties of thin films with unidirectional anisotropy

Galvanomagnetic effect was used for studying the magnetization reversal processes in thin NiFe-NiFeMn films with the unidirectional anisotropy. The experimental results were compared with the simple coherent magnetization rotation model. A large contribution of rotation of the magnetization vectorM _s to the reversal process in easy direction was found (around 22°). The dependence of angular dispersion ₄₅ on external fieldH was also measured.     

Electrical and piezoresistive properties of ion beam deposited DLC films

In present study diamond like carbon (DLC) films were deposited by closed drift ion source from the acetylene gas. The electrical and piezoresistive properties of ion beam synthesized DLC films were investigated. Diode-like current–voltage characteristics were observed both for DLC/nSi and DLC/pSi heterostructures. This fact was explained by high density of the irradiation-induced defects at the DLC/Si interface. Ohmic conductivity was observed for DLC/nSi heterostructure and metal/DLC/metal structure at low electric fields. At higher electric fields forward current transport was explained by Schottky emission and Poole–Frenkel emission for the DLC/nSi heterostructures and by Schottky emission and/or space charge limited currents for the DLC/pSi heterostructures. Strong dependence of the diamond like carbon film resistivity on temperature has been observed. Variable range hopping current transport mechanism at low electric field was revealed. Diamond like carbon piezoresistive elements with a gauge factor in 12–19 range were fabricated.     

Processing parameters and transport properties of vacuum evaporated CdSe thin films

Semiconducting thin films of cadmium selenide have been grown by conventional thermal evaporation technique on glass substrate. Films evaporated at substrate temperature equal 523 K are stoichiometric and homogeneous. Effect of various growth parameters like rate of deposition and substrate temperature on the electrical properties has been studied in details. Also, the annealed at 673 K under vacuum for 1 h films have been analyzed for resistivity and Hall effect.     

星载光电跟踪系统连续帧图像快速识别定位算法研究

为了解决星载光电跟踪系统对连续帧图像快速识别、准确定位的要求.在深入分析连续图像序列特性和星载光电跟踪系统特点的基础上,利用光电跟踪系统转台的角度变化信息,对图像序列进行帧间差值运算以获得目标残差图,并基于残差图和原始图像信息提出了一种新的目标识别定位算法,大大地减小了运算量.结合中值滤波和自适应波门跟踪算法,实现了运动目标的快速跟踪定位.通过对目标实测图像序列的实验,结果证明,该算法具有快速、稳定等优点,能满足星载光电跟踪系统实时图像跟踪的要求.     

Electro-optical properties of excitons in polydiacetylene chains

We show how to compute the optical functions (reflectivity, transmission, and absorption) of polydiacetylene chains diluted in their monomer matrix exposed to a uniform electric field in the chain direction, in the excitonic energy region. Adopting a model electron-hole potential, we derived an analytical expression for the effective chain susceptibility, which gives the optical functions. The resulting absorption shows excitonic peaks below the gap and Franz-Keldysh oscillations above the gap. The method has been applied for a 3BCMU polydiacetylene chain, showing a good agreement with experimental spectra. Received 5 November 1998 and Received in final form 23 February 1999     

Phase polymorphism and electro-optical properties of a ferroelectric liquid crystal containing the biphenyl system

ABSTRACT

In this article we present results concerning phase transitions and physical properties of the ferroelectric phase of the compound (S)-4-(1-methylheptyloxy)biphenyl–4'-(heptyloxy phenyl)-4-carboxylate (MHOBOPO7). The compound has the following phases: smectic ferroelectric C (SmC*), chiral nematic N*, and two defected phases, TGB_C and blue phase. The mesomorphic properties were investigated by means of three complementary methods: differential scanning calorimetry, polarizing light optical microscopy, and transmitted light intensity. The electro-optical measurements were carried out on an ordered sample in a middle electric field during very slow cooling from the nematic phase to the ferroelectric phase.     

高度取向的半导体聚合物薄膜的溶液浸涂法生长及其电荷传输特性研究

有效地控制有机半导体分子取向和堆积特性对实现高性能电子器件具有非常重要的意义,而发展简便高效的溶液相成膜技术是实现这一目的的重要途径.本文采用改进的溶液浸涂法,成功地成长出大面积宏观取向的半导体聚合物P(NDI2OD-T2)和PTHBDTP薄膜.偏光显微镜和极化的紫外-可见光吸收谱测量显示,薄膜中聚合物分子主链骨架沿成膜时液面下移方向择优取向.原子力显微镜观察到聚合物薄膜由纳米尺度的取向有序晶畴构成,畴的取向与分子链的取向一致.采用衬底-溶液界面处表面张力和溶剂蒸发诱导的分子自组织过程来解释浸涂法生长聚合物取向薄膜的微观机理.使用取向的P(NDI2OD-T2)薄膜制备场效应晶体管,显著地提高了电子迁移率(可达4倍),并实现高达19的迁移率各向异性度.这可归因于共轭的聚合物主链骨架择优取向引起电荷传导通路的变化.     

Thermo-e.m.f. anisotropy in magnetic films of Co and Ni and its comparison with anisotropy in electrical conductivity

Summary Films of cobalt and nickel were electroplated in the presence of an external magnetic-induction field. This resulted in the deposition of magnetic films which show, in addition to a magnetic anisotropy, also thermo-e.m.f. anisotropy. The latter is a new effect, not deriving from the anisotropy in electrical conduction deduced earlier by Kornevet al. on the basis of measurements of transmission coefficients of polarized RF field.     

掺杂钛酸钡薄膜的合成及性能研究

通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化（P）-电场（E）磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。     

掺杂钛酸钡薄膜的合成及性能研究

通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化（P）-电场（E）磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。     

掺杂钛酸钡薄膜的合成及性能研究

通过化学溶液沉积法制备的BiFeO3-BaTiO3薄膜在室温下能够同时显现铁电性及铁磁性。在600-700℃的条件下,以Pt/TiOx/SiO2/Si为载体,能够成功得到钙钛矿单相0.7BiFeO3-0.3BaTiO3薄膜。随着结晶温度上升,晶粒持续增长,最终在700℃到达更高的结晶度。由于0.7BiFeO3-0.3BaTiO3薄膜的绝缘电阻较低,它所显现的极化（P）-电场（E）磁滞回线较弱。尽管如此,由于在0.7BiFeO3-0.3BaTiO3薄膜铁的位置上添加锰,高作用场的漏电流有效地减少,最终铁电性质得到了提高。在室温下,添加了摩尔分数5%的锰的0.7BiFeO3-0.3BaTiO3薄膜同时显现铁电极化和铁磁磁化磁滞回线。