Hologram recording in glass and direct reconstruction using visible-wavelength laser beam

We propose a method of hologram recording in a glass plate by corona charging. The holographic recording materials used in this study are conventional soda-lime glass and azobenzene polymer film. A Fourier transform hologram on an azobenzene polymer film coated on the glass plate is recorded in the glass plate by corona charging. After removing the polymer film, the hologram recorded in the plate can be reconstructed using a visible-wavelength laser beam. The first-order diffraction efficiency of the hologram at a wavelength of 532 nm is 0.03%; the efficiency depends on the depth of the surface relief structure on the azobenzene polymer film and the corona-charging time. The hologram recorded in the glass plate has high environmental resistance.     

Application of Surface Relief Hologram Using Azobenzene Containing Polymer Film

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.     

The influence of UV-irradiation and support type on surface properties of poly(methyl methacrylate) thin films

Thin poly(methyl methacrylate) (PMMA) films were prepared by a solution casting on different supports (glass and aluminium plates with different gloss). UV-irradiation (λ = 254 nm) was used for polymer modification. Surface properties of PMMA were studied by contact angle measurements, attenuated total reflection infrared spectroscopy and optical microscopy. It was found that support type has no influence on surface properties of virgin PMMA, however, the changes in these properties were observed during UV modification of polymer film. The most efficient photochemical reactions appeared in sample placed on the rough Al, whereas the smallest effect was observed in polymer on the glass.     

Recording a binary computer-generated hologram on a thermoplastic film

A computer-generated hologram was recorded on a thermoplastic film using an electron-beam recording device. The hologram was a binary one of detour phase type and of surface relief type. A bright image was reconstructed from the recorded hologram.     

新型含偶氮侧链聚合物中光致各向异性及偏振全息记录

研究了偶氮侧链聚合物中光致各向异性和偏振全息, 确认在这种聚合物中分析光致各向异性动力学过程时, 必须考虑光漂白效应的影响, 测量表明该聚合物具有大的光致双折射（Δｎ ＝７．８×１０－ ３）, 并在其中记录了高衍射效率（η＝ １９．３％ ）的偏振全息图     

Direct Fabrication of Surface Relief Holographic Diffusers in Azobenzene Polymer Films

We propose a direct fabrication of light diffusers using azobenzene polymer films. Holographic recordings of surface relief diffusers are formed on the polymer film by exposure to an Nd:YAG laser (532 nm) through source diffusion materials. No post-treatment is needed, and it can be erased by heating or irradiating uniform laser beam. Diffusion pattern can be controlled by the polarization of the laser. Transmittance of over 88% is obtained at the wavelength of 633 nm.     

Ion crater healing and variable temperature ellipsometry as complementary probes for the glass transition in thin polymer films

Poly(methyl methacrylate) (PMMA) thin films of various tacticity and thickness were bombarded at grazing angles by 20 MeV Au ions at different temperatures. The shape of the tracks was investigated by scanning force microscopy (SFM) after annealing for various time at different temperatures and constant quenching rate. The thickness dependent glass transition temperature, T(g)(h), was estimated from the temperature of relaxation of ion-caused nanodeformations in the films. T(g)(h) obtained from the thermal healing of the holes and hillocks is found in good agreement with the one determined by variable temperature ellipsometry for PMMA film thickness of 80 nm and corresponds to the T(g) of each bulk PMMA stereoisomer. Below this thickness, some significant divergences are observed between the T(g) measured by the two techniques. We propose that the healing of ion crater hillock and the kink in the thermal expansion arise from the different nature of chains motions which are perturbed to different extents according to the main polymer chain preferential orientation in the thin film. This can be tentatively interpreted by a so-called "anisotropic" character of the glass transition.     

Reversible light-induced capacitance switching of azobenzene ether/PMMA blends

Fully reversible light-induced switching of the capacitance with changes larger than 50% has been achieved by using photo-active thin polymer films. The films consist of PMMA polymer blended with high concentrations of branched azobenzene ether dye molecules. Polymer thin sheet capacitors can be easily produced by spin coating and drop casting in various thicknesses ranging from 100 nm to 8 μm, respectively. Reversible capacitance switching is induced by illumination with UV and visible light, respectively. The capacitance change is correlated to the trans to cis isomerization of the azobenzene ether molecules and the alignment of the molecular dipoles in the film. Switching times depend on chromophore concentration, film thickness and light intensity used. The influence of wavelength of the light, of the temperature as well as of an electrical field applied during illumination on the capacitance change is addressed.     

恒流电晕充电对聚四氟乙烯多孔薄膜驻极体驻极态的影响

利用常温下恒流和恒压电晕充电、充电后的等温表面电位衰减、热刺激放电和扫描电镜等实 验手段研究了恒流和恒压电晕充电技术对聚四氟乙烯多孔薄膜驻极体驻极态的影响.与恒压电晕充电相比较，恒流电晕充电时由于流过薄膜的电流恒定，增加了注入电荷在多孔结构厚度方向界面处的俘获概率，使沉积电荷密度上升，改善了驻极体的储电能力.然而，这些位于不同层深多孔界面处的俘获电荷在这类功能膜储存或使用过程中，经外激发从脱阱位置 以跳动（hopping）模式输运至背电极的路径相对缩短将导致脱阱电荷衰减较快. 关键词： 恒流电晕充电 聚四氟乙烯多孔膜 驻极体 电荷稳定性     

电晕充电多孔PTFE/PP复合驻极体过滤材料的电荷存储特性

报道采用电晕充电方法，对用高温熔融粘合工艺制备得到的双向拉伸多孔PTFE与PP复合过滤材料进行驻极体改性，并采用热刺激放电和表面电位测量等方法研究了材料的电荷存储稳定性,根据驻极体相关理论，对实验结果进行了解释. 结果表明，电晕充电的多孔PTFE/熔喷或纺粘PP覆膜材料中，既存在空间电荷又存在极化电荷，复合膜的界面是电荷陷阱的主要来源. 从不同面对复合膜材料进行充电时，材料具有完全不同的电荷存储特性. 由于材料体内空间电荷和极化电荷的极性相反、相互补偿，表面电位测定并不能真正反映材料内部电荷的存储状态. 关键词： 驻极体 电晕充电 聚合物复合膜 热刺激放电     

Some relevant parameters affecting the glass transition of supported ultra-thin polymer films

We have measured, the thickness dependence of the glass transition temperature T(g)( h), using ellipsometry at variable temperature, for poly(methyl-methacrylate) (PMMA) of various tacticity in confined geometry. We report that several factors significantly affect T(g)( h): i) polymer microstructure (stereoregularity of PMMA) related to local dynamics; ii) interfacial interactions; iii) conformation of the polymer chains. These results raise many fundamental questions on the origin of the thickness-dependent glass transition. Why and how do the interactions with the substrate significantly affect T(g)( h)? Does T(g)( h) depend on the modifications of conformational parameters of the chains (their entropy)? What is the correlation between local dynamics and T(g)( h) in thin films? The aim of this paper is to summarise these open questions, which should stimulate further investigations in the thin polymer film scientific community.     

界面极化注极聚丙烯薄膜驻极体的电荷存储特性研究

本文报道一种基于双层介质界面极化机理的新型驻极体注极技术: 借助辅助层对PP薄膜进行注极. 采用表面电位测试方法考察了注极温度、注极电压对所获PP薄膜驻极体电荷存储性能的影响, 并利用热刺激放电技术研究了其高温电荷存储性能, 同时测试了PP薄膜驻极体在X和Y方向的静电场分布. 结果表明: 界面极化注极是一种比电晕注极更为优异的驻极体形成方法. 在一定温度下, 驻极体表面电位随注极电压的增加而增加, 而且两者呈线性关系, 这一结果与注极过程的电荷积聚方程的分析完全一致. 注极温度的影响研究表明, 在保持注极电压不变(注极电压范围为0.5–3.0 kV)的情况下, 温度低于75 ℃时, 温度的变化对于注极效果的影响不明显; 当注极温度大于75 ℃ 时, PP薄膜驻极体的表面电位随注极温度的增加而增加. 表面电位随时间的变化研究表明, PP薄膜驻极体具有良好的电荷存储稳定性. 对其表面电位分布的测试表明, 界面极化注极所形成的PP薄膜驻极体呈现均匀的静电场分布.     

Biomimetic, hierarchical structures on polymer surfaces by sequential imprinting

Thermal nanoimprint lithography (NIL) is based on the thermo-mechanical deformation of a polymer film above the glass transition temperature (T_g) and at an applied pressure. Sequential imprinting extends the process of thermal NIL to create hierarchical structures by carrying out secondary and tertiary imprintings at temperatures below the T_g of a polymer. In this work, we demonstrate the use of sequential imprinting technique to fabricate two- and three-level hierarchical structures on polystyrene (PS) and poly(methyl methacrylate) (PMMA) films over a temperature range of 70-130 °C, with the aim to mimic the hierarchical structures found in biological systems. By mimicking the hierarchical structure in a plant leaf, the water contact angle of PS film was increased from 95° to 128°, while the water contact angle of PMMA film was increased from 71° to 104°, without any chemical treatment.     

聚四氟乙烯多孔膜的压电活性及其稳定性

研究了经单向机械拉伸形成的非极性空间电荷型薄膜驻极体聚四氟乙烯(PTFE)多孔膜的压电性.讨论了由PTFE多孔膜和非多孔的聚合物薄膜（PTFE，聚酰亚胺PI，氟化乙丙烯共聚物FEP 和聚三氟氯乙烯PCTFE）组成的双层膜的突出压电活性.初步研究结果指出：在优化的极化条 件下形成的上述双层压电膜以外电极测量的准静态压电d₃₃常数可达186 pC/N， 这个数值与压电陶瓷锆钛酸铅PZT的相应常数接近，而比铁电聚合物聚偏氟乙烯(PVDF)的相 应常数约高出一个数量级.还研究了这类柔性多孔膜 关键词： 聚四氟乙烯多孔膜 压电性 空间电荷驻极体 充电参数 压电活性的热稳定性     

Effect of ground electrode on charge injection and surface potential of corona charged polyethylene film

The surface potential decay measurement is a simple and low cost tool to assess electrical properties of insulation materials; therefore, understanding the physical mechanisms of the surface potential decay becomes necessary. With our recent space charge measurement results on corona charged samples, bipolar charge injection on corona charged samples had been observed. Based on this new fact, it is anticipated that the ground electrode should have significant effect during corona charging and subsequently decay processes. In the paper, low density polyethylene (LDPE) film with gold ground electrode was compared with LDPE film with aluminium ground to study effect of ground electrode on charge injection and surface potential decay processes. Charging current during the corona charging, surface potential decay and space charge dynamics after corona charging in the samples with either gold coated or aluminium ground electrode were measured. Differences have been observed for gold ground electrode when compared with aluminium ground electrode. Higher work function of gold electrode is responsible for the observed differences. A preliminary simulation has also attempted to show that the bipolar injection may take place in corona charged LDPE films.     

Enhancement of the measurement sensitivity in multiple-exposure holographic interferometry

Specific features of reconstruction of enhanced-sensitivity interferograms in the optical processing of a multiple-exposure hologram recorded under linear conditions are considered. To enhance the measurement sensitivity when visualizing the changes in the state of an object under study that take place during the time between exposures, it is proposed that the holographic structures corresponding to these exposures on a new carrier be rewritten and the double-exposure hologram thus obtained under nonlinear conditions be recorded. The proposed technique of enhancement of the measurement sensitivity was experimentally tested when visualizing a change of the temperature field in a flat glass plate.     

Improving electret properties of PP filaments with barium titanate

Barium titanate (BaTiO₃) containing polypropylene (PP) composite filaments were melt spun to modify polymer electrostatic charging characteristics. Sample filaments were charged with a corona instrument and their surface potentials were measured. Initial surface potential as well as potential stability was monitored through an accelerated decay procedure. It was found that both BaTiO₃ concentration and charging temperature influence the charging characteristics of the fibers. When BaTiO₃/PP composite filaments were charged at 130 °C, significant enhancements were observed when compared to samples charged at room temperature. The distribution of BaTiO₃ particles within the filaments and changes in the crystal structure were also examined.     

含咔唑与偶氮分散红共聚物的表面增强共振拉曼光谱研究

借助于表面增强共振拉曼光谱散射(SERRS)技术,研究了一种新型的偶氮聚合物材料侧链含咔唑与偶氮分散红共聚物(CAP)在化学沉积法制备的银膜表面的拉曼峰增强和吸附行为。实验结果显示,CAP在银表面的状态为: 聚合物通过咔唑单体中咔唑基团和偶氮单体中硝基与银膜衬底发生物理吸附,而聚合物的主链与衬底相距较远没有相互作用。可以推测,聚合物在衬底表面的这种状态将对偶氮光存储器件的稳定性和工作效率产生不良影响。     

Electrical properties of polylactides

A PLA film with low crystalline-phase content was investigated in a DC field within the temperature range of 25–70 °C. The polymer exhibits low electrical conduction with increasing activation energy within the area of the glass transition temperature. Electrets were made from the PLA film precursor using an isothermal polarization method. The charge on the electrets was assessed by measuring the field intensity. The surface charge of an electret has the character of a hetero-charge. After 4 months from termining the isothermal charging and cooling, the PLA film polarized at E_p > 16.7 MV/m was affirmed the applicable electret properties.     

Interferometry for measuring large aspherical surfaces with holographic optical elements

Interferometry for measuring the shape of large aspherical surfaces is reported. The interference fringe pattern between the parallel reference beam and the reconstructed wavefront from the master zone plate which is drawn by an electron-beam drawing machine is recorded on a hologram plate with off-axis optical arrangement. The hologram plate used as the standard element is reconstructed by the conjugate beam in a modified Twyman-Green interferometer. Insufficient parallelism of commercial hologram plates can be compensated by this method. It is also easy to make replicas. Some experimental results are also presented.