亚微米聚焦离子束的漂移现象

研究李亚微米聚离子束（ＦＩＢ）系统的漂移现象，给出了测量漂移的方法，分析引起漂移的原因及降低漂移的措施，发现了偏转电极上的钝化层及污染物充电电荷所引起的漂移现象；测出了各电极电压变化所引起民漂移的大小；发现了由于外壳温度不均匀引起离子枪轴线相对样品变化所引起的漂移。提出了制作透镜电极时保持轴对称、特别是限制光栏必须位于透镜光轴的必要性。所给出的数据漂移数据既包含早期的单组透镜ＦＩＢ系统的数据，也包     

计算电容与电学阻抗的绝对测量

本文叙述中国计量科学研究院研制的计算电容的结构特征,给出了由于电极系统几何形状偏离理想状态所引起的平均电容量误差计算公式,并给出了计算电容的综合误差。文中还介绍了基于计算电容所进行的电阻单位的绝对测量以及复现绝对亨利的工作,并对为此目的而研制的整套测量装置和标准作了简要介绍。     

强流微束斑电子束系统的研究和设计计算

本文研究了强流微束斑电子束的形成问题。提出了一种采用新型磁透镜的电磁复合聚焦系统，这种新型电子束系统的轴上磁场在电子束束腰附近达到极大值，并且轴上磁场分布关于其极大值不对称。利用附加电极在磁场较强的区域构成具有拒斥电场的电透镜，以充分抑制空间电荷推斥力的散焦作用。利用描述电流密度分布演化的变态伏拉索夫方程，研究了强流微束斑电子束系统，数值分析研究了透镜激励和电子束初始条件对于电流密度分布演化的影响。发现侧极靴透镜和相应电极形成的电磁复合聚焦场对于强电流电子束具有优秀的聚焦效果，设计出了利用侧极靴磁透镜的新型电子光学系统，这种系统可以形成电流达到1．96mA、束斑半径仅为4．2μm的强电流微束斑电子束。     

基于微扰理论的静电电子透镜的缺陷电场计算

研究了用于计算电子光学系统的缺陷电场和容差的微扰理论。基于微抗原理，推导了计算静电电子透镜由于电极偏心、倾斜和加工不圆造成的电场变化及其旁轴多极场展开函数的九点有限差分公式，编制了计算软件。建立了两个电场解析模型，通过该模型的解析解与数值计算结果的对比，证实了算法及软件的正确性，并据此讨论了微扰理论用于容差计算的适用范围。计算了几个静电电子透镜的例子，给出了不同电极缺陷的电位分布和微扰多极场分布。     

基于复杂类型数据的发现特征子空间模型(DFSSM)的研究

探讨围绕知识发现领域中较为宏观、较为重大的问题。首先，根据复杂类型数据（包括Web数据、多媒体数据、空间数据、时间序列数据等）所具有的非线性动力学性质和特征，采用模式（定义为Hilbert空间中的矢量）来定量地表征复杂类型数据的多变性及具有的不确定状态和行为，并用模式的变化来刻画其整体知识发现过程的发展和演变规律；其次，以知识发现系统内在机理的研究为基础，构造了复杂类型数据知识发现系统的总体结构模型——发现特征子空间模型DFSSM；最后，用基于Web的文本挖掘系统和基于图像信息（气象云图）的知识发现系统作为实例进行了验证，结果表明DFSSM方法对于非结构化的文本数据及图像数据类型的知识发现过程具有指导性作用。因此，该结构模型具有较好的实用性与普适性，有望拓展到其他复杂类型数据的知识发现过程中。     

反射式光纤测振仪的研究

提出了一种反射式光纤测振系统。为克服环境、温度、光源输出、光路损耗等变化引起的漂移，它采用与反射面距离不等的两根接受光纤为参考通道，并利用两根接受光纤输出的信号比构成自补偿网络。本文给出该网络的理论依据，并介绍如何在电路设计上采用相应措施来提高稳定性和保证测试精度     

微通道板电极表面的XPS分析

为探索微通道板的噪声来源，利用X射线光电子能谱对国内和国外MCP电极表面进行组分分析。实验发现，在国外MCP电极表面上只检测到Ni，Cr，C，O等原子谱峰，而在国内的MCP电极表面还检测到K，Na，Si等原子谱峰，且在国产未镀电极的MCP表面检测出K的原子谱峰。分析认为，MCP体内的K有向表面偏析的现象；MCP电极表面上的杂质，如K，Na，Si等是MCP噪声来源之一；国产MCP表面的杂质不仅与MCP镀膜材料纯度、系统真空度有关，而且还与电极膜层的致密性有关。     

多面体转镜扫描系统入瞳漂移现象的讨论

在激光扫描测量中，扫描器的引入误差是影响测量精度的因素之一。本文对多面体转镜扫描系统的入瞳漂移现象进行了详细讨论，推导出入瞳漂移量的数学表达式，为实际应用中选择扫描系统的布局方案和减小入瞳漂移引起的测量误差提供了理论依据。     

德国联邦物理技术研究院（PTB）气体微流量计量评介

在真空技术应用中，高精度气体微流量计用于连续膨胀法校准系统压力的产生、漏孔漏率的测量以及真空泵抽速的测定。FIB先后研制了三代气体微流量计，第一代为手动型，第二代为半自动型，第三代为全自动型。本详细介绍了FIB研制的气体微流量计的性能和特点，并介绍了气体微流量计在真空漏孔的漏率测量方面的应用。另外，还介绍了FIB最近研制的大气压力下漏孔漏率测量系统的性能和特点。     

大型试件的精确定位方法与调控系统的研究

本文深入分析了在大型精密仪器上对大型试件精确定位时，调控系统产生机械＂爬行＂和机械＂漂移＂的机理；提出了实现精确定位的状态一致原则和功能分离原则。介绍了根据上述原则研制的自动精确定位系统，该系统在调整５００ｋｇ大型试件时的定向精度可达２×１０－７ｒａｄ。     

长距离同轴度测量方法及实验

本文介绍了一种新型的自适应双频激光同轴度测量系统，该系统利用两个完全对称的渥拉斯顿棱镜，一个作为测量元件，另一个作为补偿元件，采用比相技术处理测量信号，因而测量元件可以暂时移出光路，能够进行同轴度的测量，系统的光学设计使激光光束的平衡和角漂不影响测量结果，对激光的漂移有自适应性，两束干涉光基本符合共光路原则，因而对大气湍流，空气扰动的影响具有更强的适应性，可用于长距离直线度，同轴度的测量。该系统与     

亚稳态氪原子束流诊断系统结构设计与优化

亚稳态氪原子具有较高的内能,在金属表面碰撞时会激发产生电子,利用电子透镜对退激发电子进行成像与检测,即可实现亚稳态氪原子束流强度以及空间分布的表征。基于该原理设计了一种亚稳态氪原子束流成像系统,采用有限元分析方法研究了电极间距、厚度与电势对退激发电子束流运动的影响规律。结果表明:成像弥散随着电子透镜聚焦能力的提升而减小。其亚稳态氪原子束流各物点成像误差在2mm以内,成像大小为 16.5mm,平均误差为3.71%,最大误差为9.38%。     

折反射式连续变倍扩束系统的设计

为了用同一台仪器获得不同口径的激光准直光束,设计了一个连续变倍激光扩束系统,系统扩束比可在55～155之间连续变化,可以得到比传统扩束系统更大的激光光斑,满足对大口径激光束应用的要求.该系统由两级扩束子系统构成,一级折射式无焦变倍扩束系统实现激光光束口径连续变化,变焦系统选用仅有4片透镜的三组元结构,并采用"正-负-正"的形式,有利于减小系统整体结构尺寸.考虑到可能产生的热形变,对入射光斑较小的变倍移动组的材料进行了分析选择.二级折反射系统实现激光束的高倍率扩束,由球面反射镜取代离轴抛物面镜,用一片弯月透镜补偿像差.由于单透镜折射元件对系统性能影响很大,对其结构形式和材料进行了分析,确定了透镜的厚度与材料.应用光学设计软件CODEV给出了系统的优化设计,设计结果显示该系统像差得到了很好地校正,成像质量达到衍射极限.最后用Light tools软件进行三维建模分析,系统准直度与理论设计值相符.     

The effect of the conductivity of drift chamber walls on the dynamics of a relativistic electron beam with a virtual cathode

The effect of conductivity of walls of a drift chamber of the axial vircator on the behavior of a relativistic electron beam with a supercritical current was investigated. The dynamics of a relativistic electron beam is shown to be characterized by the formation of a virtual cathode of complex structure with two or three potential minima in the azimuthal direction, which rotate around the drift space axis. It is established that variation in the conductivity of drift chamber walls leads to stepwise switching of the generation frequency and a sharp change in the output power. Dependences of the output radiation power of the investigated vircator system on the conductivity of drift chamber walls for two characteristic regimes of the dynamics of a relativistic electron beam were obtained.     

High-aperture diffraction of a scalar, off-axis Gaussian beam

A scalar treatment for Gaussian beams offset from the optic axis and then focused by a high-numerical-aperture lens is presented. Such a theory is required for describing certain types of Doppler microscopes, i.e., when the measurement is simultaneously performed by more than a single beam axially offset and then focused by a lens. Analytic expressions for the intensity in the focal region of the high-aperture lens are derived. From these expressions we calculate the intensity in the focal region with parameters of beam size, beam offset, and the numerical aperture of the lens. The relative location and variation of the intensity around the focal region are discussed in detail. We show that for small-diameter Gaussian beams the Strehl ratio increases above unity as the beam is offset from the optic axis. This is explained by the increase in the effective numerical aperture of the offset beam compared with the one collinear with the optic axis. From examining the focal distribution, we conclude that it rotates for small beam size and that increasing beam diameter causes the focused distribution to rotate and shear, i.e., to distort. We also show that the distortion of the distribution increases with increasing numerical aperture.     

Energy spectrum of a multicomponent flux of accelerated ions

We have experimentally studied the energy spectrum of an accelerated ion beam moving in a drift gap upon separation by a grid electrode system from a metal plasma jet of a pulsed high-current vacuum arc. It is established that the average energy per unit ion charge in the beam is below the value corresponding to the accelerating voltage. The width of the energy spectrum of accelerated ions is close to their average energy and significantly exceeds the width of the energy spectrum of the initial beam. The results of model calculations show that the observed phenomena can be explained by the action of a nonstationary electric field of the space charge of the ion beam transported via the drift gap.     

Reshaping of a Divergent Elliptical Gaussian Laser Beam Into a Circular, Collimated, and Uniform Beam With Aspherical Lens Design

In this paper, we present a specific optical system of two aspherical lenses designed to circularize, collimate, and expand an edge-emitting semiconductor laser beam and transform its irradiance distribution from Gaussian to a uniform-square distribution for possible application in light detection and ranging sensors. It is verified that the diffraction effects are negligible so that geometrical ray optics is used to design this optical system. To accomplish the design, the source beam profile is decoupled into two independent beam profiles represented in two transverse directions. Analytical equations specific to this lens system are derived and MATLAB is used to solve these equations and simulate a design example. Results are presented for a specific example.      

Focal shift and focal switch of partially coherent flat-topped beams passing through an alignment and misalignment lens system with aperture

The focal shift and focal switch of partially coherent flat-topped (PCFT) beams passing through a lens system with an aperture are studied in detail. We have shown that a focal shift is also present for beams propagating through an aligned optical system and the amount of the focal shift depends not only on the radius aperture of the focusing system, but also on the spatial coherence and order of the flat-topped beam of the incident partially coherent light. A new phenomenon called ‘focal switch’ occurs for misaligned optical systems, i.e. the focal shift experiences a sudden transition as the aligned optical system becomes misaligned, and the influence of the spatial coherence, order of flat-topped beam and aperture size reduction, on the focal switch is investigated in detail. Finally, the necessary conditions for the focal switch to take place are investigated.     

Interaction between a vortex and an edge dislocation nested in a cos‐Gaussian beam passing through a tilted lens

The interaction between a vortex and an edge dislocation nested in a cos‐Gaussian beam passing through a tilted lens was studied analytically and numerically. It is shown that in the presence of the tilted lens, by varying the cos‐part parameter of the beam, the slope of the edge dislocation, or the tilt coefficient of the lens, the topological charge is conserved for the case of the off‐axis edge dislocation, while charge conservation does not hold true for the case of an on‐axis edge dislocation, irrespective of the on‐axis or off‐axis vortex. The relation between the transverse positions (x, y) of vortices and the tilt coefficient is linear, and is interpreted.     

矩形弹性中厚板的短梁函数解法

本文给出承受均布载荷和集中载荷作用的短梁的梁函数。应用梁函数构造矩形中厚板的基函数系。应用最小势能原理可以求得承受任意载荷作用的矩形弹性中厚板弯曲问题的多项式近似解。计算结果表明精度较高。当板的剪切刚度C→∞时,本文结果与结果相一致。