液体CT探测器控制系统的设计与实现

为加强航空器的安全防范工作,实现液体的不开瓶安全检测而研发的液体CT探测器是一种用射线源对液体进行CT检测的装置。本文针对液体CT探测器设计了基于PLC的控制系统,实现了液体CT扫描探测所需的扫描运动控制,旋转台的自动精密定位,射线源自动训管,射线源高低压及束流控制选择、以及PLC与主机的RS232双向链接闭环控制,PLC与探测器板的RS232通信,自动报警等功能,并在VB6．0环境下,开发了上位机监控程序,实现了上位机对PLC的系统初始化、控制命令发送、系统状态显示等任务。整个系统结构简单,可靠,调试方便,为CT成像实验建立了一个精密量化的,可视的,参数可调的数控实验平台。     

X射线平板探测器背板工艺研究进展

从高像素填充因子、低噪声、高帧频、高空间分辨率及柔性五个方面对近些年X射线平板探测器背板工艺的研究进展进行了综述.通过对研究过程中的材料选择、像素结构和读出电路优化的详细阐述,分析了X射线平板探测器背板工艺的研究现状及改善方向.文章同时从新结构、新材料、电路设计及三维探测设计四个方面给出了X射线平板探测背板技术未来的发展趋势.     

一种基于石墨烯电场效应的软X射线探测器简

针对脉冲星导航对软X射线探测的实际要求,研究分析了一种基于石墨烯电场效应的软X射线探测器的性能.通过理论计算,并利用COMSOL Multiphysics有限元仿真软件,给出了探测器时间分辨率和能量分辨率的估值公式.在5.9 keV软X射线入射硅吸收层的情况下,时间分辨率的理论值可达7.2ns,能量分辨率的理论值约为90 eV(1.5％).结果表明,该探测器能够初步满足脉冲星软X射线的探测需求.     

基于嵌入式系统的X射线探测与数据采集系统

本文提出了一种基于嵌入式系统的脉冲式X射线源探测与数据采集系统的设计方法,能够很好地实现X射线到电信号的转化,再由高速A/D转换器转换为数字信号.系统利用基于ARM的嵌入式Linux操作系统对数字信号进行数据存储和管理,并通过以太网进行数据传输,减小了数据传输的误码率,提高了系统的抗干扰能力.     

X射线探测技术

1 引言X射线探测器是用来接收X射线，并把它转化成为可测量或可观察的量的仪器。所有X射线探测器都是基于X射线和物质相互作用的各种特性制成的。根据测量原理，可把X射线探测器分成三类，即：1）零维探测器，包括各种类型的正比计数器和半导体探测器等；2）二维探测器，包括X射线底片、电荷耦合器件（CCD）、X射线成像板、电子变焦管等；3）三维探测器，目前主要是光刻胶。2 X射线零维探测技术所谓零维探测，是指只能探测X射线光子数或X射线强度的技术。零维探测器包含各种计数器，如正比计数器、盖革计数器、闪烁体及半导体探测器等…     

离子注入型Si-PIN半导体探测器的研制

本文系统地介绍了Si-PIN探测器对带电粒子、中子、射线的探测原理.针对灵敏面积为φ30mm×420μm的Si-PIN探测器,详细地介绍了设计方法和工艺流程,并指出了影响探测器性能的关键工艺.采用离子注入和平面工艺不仅能够降低漏电流,提高探测器的能量分辨率,而且使得探测器对高温环境和真空都很稳定.最后初步介绍了探测器的电特性(I-V特性,C-V特性)的变化趋势,以及探测特性参数的测量方法.     

空间X射线数据信息的组织管理和提取

针对空间X射线观测的数据结构复杂、数据量庞大,难以很好地利用的问题,文章研究了空间X射线的探测原理、X射线数据信息的组织管理和数据的探测平台,提出了快速提取空间X射线的信息的方法。通过文章的研究不仅能够使空间X射线数据的有效组织管理优化,而且能快速的提取X射线源的有用信息。     

基于多元约束的小型软X射线偏振望远镜光学设计及优化

作为揭示物质在强磁场、强引力场中的行为方式以及天体辐射偏振产生原因的重要手段，X射线偏振探测在近40年来一直是高能天体物理的研究热点。小型软X射线天文偏振探测望远镜采用抛物面聚焦方式将X射线会聚至探测器处，通过在反射镜表面镀制多层膜实现高反射率和能量分辨。文中对小型天文偏振望远镜抛物面的两种空间布局方式，即中心环绕旋转式镜面布局和交叉对称式镜面布局进行了理论分析，构建了综合集光面积和制作难度的优化模型，基于多元约束方式进行了参数优化。结果显示，在系统口径受限、探测器有一定尺寸的实际应用环境中，参数优化后的交叉对称式镜面布局方案较常规中心环绕式设计更有优势，既能获得较大的集光面积，又能兼顾镜面加工的可行性。     

碘化汞(HgI_2)半导体探测器Ⅹ射线能谱仪

本文概述了HgI_2室温半导体探测器的原理.用这种探测器构成的X射线能谱仪,具有体积小,重量轻,能量分辨率好,探测效率高,灵敏度高等特点.文章还给出了谱仪系统的能谱特性,并简略介绍了在X射线荧光分析中的应用.     

基于X射线检测的电力电缆常见缺陷分析

X射线数字成像技术由于高灵敏度、无损检测等优势,可以检测出常规手段较难直观判断的设备缺陷部位及老化状况,近年来在电力电缆的缺陷检测中的应用越来越多。本文在阐述了X射线检测原理和检测参数的基础上,例举了2个X射线检测现场受损电缆的实际案例。在电缆外护套受损的情况下,通过X射线成像,可以快速判断主绝缘层是否有缺陷。非破坏性的X射线检测方法是一种高效的、节约成本的现场检测技术。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.