New liquid‐crystal alignment agents based on fluorinated polyimides with trifluoromethyl‐substituted benzene or diphenylether in the side chain

Fluorinated copolyimides derived from 4,4′‐oxydiphthalic anhydride (ODPA) with 4,4′‐oxydianline (ODA) and trifluoromethyl‐containing aromatic diamines have been synthesized and characterized. The trifluoromethyl‐containing diamines include 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, 3,5‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] benzamide, 3,5‐diamino‐1‐[(3′‐trifluoromethyl) phenyl] benzamide, 1,4‐bis(4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl) benzene, 3,5‐diaminobenzenetrifluoride, 4,4′‐diamino‐4″‐(p‐trifluoromethyl phenoxy) triphenylamine, and 4‐[(4′‐trifluoromethylphenoxy) phenyl]‐2,6‐bis(4″‐aminophenyl)pyridine. Strong and flexible copolyimide films, produced by casting the polyamic acid solution followed by thermal imidization, exhibited great thermal stability and high mechanical properties. The polyimides had an ultraviolet–visible absorption cutoff at 330–340 nm and pretilt angles as high as 20° for nematic liquid crystals, making them great potential candidates for advanced liquid‐crystal display applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1583–1593, 2002     

显示技术的演进与应用

This paper overviews some display technologies which play main roles on today＇s display market. And new technologies which may be used for tomorrow＇s display technologies have been discussed. New technologies will boost the development of display technologies.     

基于PC机的虚拟现实技术研究

本文利用所需额外硬件很少的立体显示技术,研制了一种基于微机平台的虚拟现实系统。这个系统利用最新推出的微机版的三维图形标准Open GL建模,以实时动画形式实现了真正的交互性,立体视觉效果明显,可以给观赏者提供真实的临场感和亲自控制的参与感。与已研制出的“三维立体显示系统”相比,有了实质性的进步。     

Display and applied holography in museum practice

Possible applications of holography for cultural heritage study, demonstration and restoration, particularly in practical museum applications, are discussed. In this respect two main applications of holography are of interest: display holography and technical holography. The latter includes holographic NDT methods, three-dimensional measurements of objects, memory systems, and so on.     

投影阵在空间解析几何中的应用

本文得到了空间直线和平面的投影阵，并举例说明了它在空间解析几何中的应用。     

Functional integrals in the statistical theory of turbulence and the burgers model equation

The functional integrals appearing in master equations for turbulent flow of an incompressible fluid and for the Burgers model equation are treated. A possible way is described to define the integration properly and related problems are discussed. For the simple example of the Burgers model equation of turbulence some results are presented.     

基于DSP的新一代液晶光电图形发生器

液晶光电图形发生器选用先进的液晶显示器件,在计算机的控制下可根据实际测量的需求产生出各种所需的目标图形。针对第一代光电图形发生器数据传输速度过慢等问题,研制了新一代基于DSP的光电图形发生器,采用通用异步接收/发送通信外设的接口方式,通过高性能DSP与FPGA进行图形传输,利用专用的液晶驱动芯片完成图形显示。结果表明,该装置提高了传统光学测量中对目标更换的效率和图形传输速度,实现了从目标到探测的全光电化测量。     

微型投影机光学引擎的研究

设计了一种针对个人用户使用的微型投影机光学引擎,系统为单片式数字光线处理器结构,采用红绿蓝三色大功率高亮度发光二极管作为光源,使用X棱镜作为合色元件,从而实现38.1～50.8 cm的彩色投影显示.对设计结果进行理论分析后可知,设计结果满足投影显示对颜色的要求,光学引擎的理论效率为16.1%.同时利用Light Tools仿真软件对系统进行建模分析,300万条光线追迹仿真的结果表明,光学引擎的效率为14.6%,与理论分析结果基本符合,屏幕上光通量为22.8 lm,其美国国家标准协会规定的九点照度均匀性达到91.55%和-93.36%,满足设计要求.     

一种新的三维计算全息图的计算方法

介绍了一种制作真实三维物体计算全息图的新方法。用摄像机记录三维物体在非相干光照明条件下两个正交方向上不同视角的一系列投影像，将这些投影像导入计算机，在MATLAB中对其作快速傅里叶变换。对这一系列二维投影像的傅里叶变换图进行抽样，得到三维物体在透镜后焦平面上的光场分布，进而制成一张计算全息图。结果证明该方法可以实现对真实物体三维全息图的合成，并且在算法实现上更加简单，提高了程序的运行速度，有利于改善全息图再现像的质量。为解决真实物体相干全息记录中光源功率和相干长度对全息记录可行性的限制指出了一个新的方向。     

生长温度对纳米氧化锌场发射性能的影响

采用锌粉和银粉为蒸发源,用热蒸发法不同温度下制备了四针状纳米氧化锌,并以单独的锌粉做对照。采用扫描电子显微镜(SEM)观察其形貌,X射线衍射(XRD)谱表征其晶体结构。采用丝网印刷方法将其制备为场致电子发射阴极,将阴极与印刷有荧光粉的阳极板组装成二极结构场致发射显示屏,并进行了场致电子发射特性对比实验。结果表明较高温度制备的氧化锌具有较好的场致发射性能;掺杂银粉的蒸发源制备的样品的发射性能明显优于没有掺杂银粉的样品。实验证明ZnO是一种优良的场致发射冷阴极材料,在真空电子方面具有广阔的应用前景。