平面偏振光场光弹性实时相移法

光弹性法可广泛用于二维、三维应力或应变场的研究。根据偏振相移法的原理,提出一种新的积分相移法,并设计了用于全场等倾线和等差线实时分析的光弹性仪。在正交偏振光场下,按一定速度同步旋转起偏镜和分析镜,CCD摄像机可连续获取四幅相移光弹图像,由CCD像敏单元积分获得其光强值,通过所提出的相移法运算,可以迅速地得出全场等倾角和等差线的相位值。该方法和装置不仅可用于光学原件及玻璃制品的高速检测,而且也可用于随时间缓慢变化的光弹性分析中。     

Fine structure extraction without analyser function measurement

A method for fine structure extraction from spectra of charged particles is described. Two experimental spectra are registered from the same object but with different and unknown analyser functions. The relation between these two analyser functions is known. The method is illustrated by fine structure extraction from silver Auger electron spectra.     

Comparison of in vitro breast cancer visibility in analyser‐based computed tomography with histopathology,mammography, computed tomography and magnetic resonance imaging

High‐resolution analyser‐based X‐ray imaging computed tomography (HR ABI‐CT) findings on in vitro human breast cancer are compared with histopathology, mammography, computed tomography (CT) and magnetic resonance imaging. The HR ABI‐CT images provided significantly better low‐contrast visibility compared with the standard radiological images. Fine cancer structures indistinguishable and superimposed in mammograms were seen, and could be matched with the histopathological results. The mean glandular dose was less than 1 mGy in mammography and 12–13 mGy in CT and ABI‐CT. The excellent visibility of in vitro breast cancer suggests that HR ABI‐CT may have a valuable role in the future as an adjunct or even alternative to current breast diagnostics, when radiation dose is further decreased, and compact synchrotron radiation sources become available.     

衍射增强成像信息分离方法研究

衍射增强成像（DEI）是一种功能强大的相位衬度成像技术,对于软组织,它能获得比基于吸收的传统X射线成像技术更高的衬度.研究了一种基于DEI的信息分离方法,它能同时获得三种参数图像,即吸收像、折射像和小角散射像.信息分离利用解析方程求解,获得的参数图像质量取决于在三个不同的分析晶体角度处获得的DEI图像.利用矩阵条件数对方程求解的稳定性进行了讨论,推导出理论上的折射角和小角散射宽度的最大值.最后,利用豚鼠耳蜗DEI图像对研究结果进行了验证. 关键词： 信息分离 衍射增强成像 矩阵条件数 豚鼠耳蜗     

The alignment of spectrometers and quantitative measurements in X-ray photoelectron spectroscopy

The alignment of the sample in X-ray photoelectron spectrometers is usually made to optimize the spectral intensities. There are two important classes of spectrometer: (i) those in which the analyser acceptance area is independent of the analysed electron kinetic energy; and (ii) those in which this area varies. Model experiments show how an example of a VG ESCALAB II conforms to class (i) whereas an example of an SSI X-probe is of class (ii) and shows an analyser acceptance area which depends approximately inversely on the emitted electron kinetic energy. This latter result means that the SSI X-probe spectrometer must be aligned for the electrons of the highest kinetic energy (smallest analyser acceptance area). A misalignment of 0.1 mm in the sample height can cause a 10% change in the relative intensities between 0 and 1000 eV binding energies. This dependence of the analyser acceptance area with energy is an effect likely to be common in the advanced electron optical systems of modern electron spectrometers and should be understood in order to use such spectrometers effectively. Such dependencies should be determined by analysts for their own instruments in the operating mode that is used for conducting work in which the repeatability of intensity measurements is important.     

A design for a cylindrical mirror analyser for use in auger spectroscopy

The design of a cylindrical mirror analyser for use in Auger spectroscopy is discussed. The main feature of the design is the use of hemicylinders in place of the usual full cylinders. Although there is a consequent loss in solid angle of collection the loss is offset by a relaxation in machining tolerances, greater access to the specimen, and a simpler method of construction. An analyser built to this design has been operated and found to have a resolution of 0.35% for a semiangular aperture of ± 6°. The limitation on resolution appears to be set by the size of the incident electron beam on the target.Auger and loss spectra obtained with the analyser are shown and compared with those for the same material obtained with a conventional retarding-field analyser.     

Monodispersion of the Investigated Flow in the Sorting Unit of a particle size optical and electrical analyser

The use of a compact cylindrical piezoelectric transducer in the jet dispersion unit of the sorting system of an optical or electrical particle size analyser is discussed. Solving two equations for the shift distribution in a piezoelectric transducer with a running fluid chamber, important expressions for the vibrational velocity of acoustic terminal, mechanical impedance, of the stable part of the jet are obtained. The practical application of this technique is illustrated by the calculation of desi parameters for an industrial dispersion unit used in an H.cytophotometer (Ortho Instruments, USA). Good agreement between theoretical and experimental results is shown.     

Nondestructive and complete Bell-state analysis for atomic qubit systems

This paper realizes a nondestructive and complete Bell-state analysis for atomic qubit systems by a designed nondestructive and complete Bell-state analyser. In the scheme, Bell states are completely discriminated by two bits of classical informations which comes from the locality single atom detection on two auxiliary atoms, during which the Bell states are not affected. The needed devices are well within the bounds of current technology, and then the scheme is experimentally feasible.     

全自动通用胶片判读仪光学装调

GP-111B判读仪,是光机电结合的一种高精密仪器,本文只对光学系统方面的装校调试作以介绍。     

Angle-resolved ups measurements in a modified LEED system

A LEED chamber has been modified to include a differentially pumped discharge lamp (He or Ne) and an additional retarding grid electron energy analyser for UPS. This small analyser is located at right angles to the LEED analyser and does not interfere with normal LEED and Auger operations. The UPS signal is amplified by a channel plate multiplier and accelerated onto a phosphor-coated screen. Directional information is obtained by scanning this screen with a collimated photomultiplier detector. A phase-lock amplifier is used to differentiate the signal from the photomultipler. Alternatively the phosphor screen can be used as a collector to measure a total spectrum. The acceptance angle of the UPS analyser is 90°. In the angular resolving mode it is possible to observe emission from a (100) fcc crystal in the 〈100〉, 〈110〉 and 〈111〉 directions with a fixed incident photon angle in the range 20–40° to the normal. The acceptance angle of the detector was usually ~7° but this can be varied by changing the collimating tube on the photomultipler. The direction dependent features of the d-band spectrum of clean nickel with a (100) surface have been examined. Characteristic features were observed for each of the 〈100〉, 〈111〉 and 〈110〉 directions. These are compared with those reported for crystals with the corresponding surface orientations. The effects resulting from the chemisorption of nitric oxide on this nickel crystal have also been investigated.     

含缺陷光子晶体传光特性的实验研究

选择MgF2和ZnSe两种材料设计制作了一维缺陷光子晶体,从理论和实验上对带有缺陷的一维光子晶体的传光特性进行了研究.在实验中,一般用光谱仪来测量通过光子晶体的透射光谱,由于光谱仪价格较贵,这种方法不利于制作实用的光子晶体传感器.我们用CCD和光栅代替光谱仪,利用白光光源代替激光器,建立自动测量实验系统进行了实验研究.实验中利用压电陶瓷来改变缺陷层厚度,模拟缺陷层的变化,通过CCD测量衍射光位置来测量透过的光频.实验结果表明,缺陷层厚度的变化和透射光频率之间呈线性关系,通过测量透射光频的变化,可以测量引起缺陷层变化的物理量,这与理论分析一致,说明本实验方法可行.本实验方法研制实用的光子晶体传感器具有一定意义.     

The quantitative interpretation of peaks in photoelectron spectra obtained with dispersive electrostatic analysers

General expressions are obtained which show the relation between the height and area of a photoelectron peak and the partial photoionisation cross-section. It is shown that, if the height is used as a measure of intensity, the energy spread of the incident photon beam and the analyser bandpass must be considered. The importance of having a complete knowledge of the variation of analyser efficiency with electron energy is stressed, the cylindrical mirror analyser being given as an example.     

Esca microscope — a new approach for imaging in XPS

This work demonstrates the feasibility of a novel yet simple method of obtaining XPS images using a conventional X-ray photoelectron spectrometer with a minimum of modification. A spherical sector electron energy analyser is operated in the selected area mode (small input aperture, moderate lens magnification) and deflection plates are introduced between the input lens and the sample, allowing the virtual image of the input aperture to be raster-scanned across the sample surface. The image is then formed by using the customary spectrometer output to z-modulate a synchronously raster-scanned video monitor. At present, the resolution is 150 μ but improvements to 10 μ should eventually be possible. Examples are given of studies on electronic components with insulating and conducting areas.     

Annihilation-in-flight of polarised positrons with polarised electrons as an analyser of the positron polarisation from muon decay

The use of annihilation-in-flight of arbitrarily polarised positrons with arbitrarily polarised electrons as an analyser for the positron polarisation from muon decay is discussed. Analysing powers for the longitudinal and the two transverse positron polarisation components are derived and algorithms for the simulation of polarised muon decay and of annihilation-in-flight are given. PACS 13.88.+e; 13.35.Bv; 12.60.-i; 11.30.Er; 02.70.Uu     

Experimental mode coupling analysis in optical waveguides for sensor and component optimization

A computer controlled mode coupling analyser is conceived and described in detail to characterize and to analyse mode coupling in all known kinds of cylindrical, multimode, step index, optical waveguides (CMSIOWs) by experimental measurement. These waveguides can be present in many ways like simple fibres, multimode fibre-optic sensors (MFOS) or other optical components like couplers or modulators. The computer processed results of measurements lead to transfer matrices and modulation transfer matrices. The transfer matrices describe the light distribution in the far field of these waveguides depending on the direction and power of the light that is injected into it. By visualizing the modulation transfer matrices in the form of mesh diagrams, the influence of external physical parameters, like a measured variable, on the mode coupling mechanisms inside CMSIOWs can be shown directly. The computer controlled mode coupling analyser will make the optimization of MFOS more efficient and, moreover, it will ease modelling of CMSIOWs and define their properties. The potential field of applications for the mode coupling analyser will be in engineering and optimization of intrinsic multimode fibre-optic sensors and their components.     

Measurement of the transmission function of the hemispherical energy analyser of ADES 400 electron spectrometer

For determination of the transmission function of a hemispherical energy analyser of an ADES 400 photoelectron spectrometer (V. G. Sci.) a direct method is used. This method is based on the definition of the transmission coefficient of an energy analyser. The number of impinging electrons from an electron gun is measured by a Faraday cup and the current of passed electrons is determined as a peak area of the current signal from the channel multiplier which is used as the Faraday cup. The transmission function of the energy analyser of the ADES 400 photoelectron spectrometer is measured for four values of the analyser pass energy.Presented at the Seminar on Secondary Electrons in Electron Spectroscopy, Microscopy, and Microanalysis, Chlum (The Czech Republic), 21–24 September, 1993.     

Multiple‐element spectrometer for non‐resonant inelastic X‐ray spectroscopy of electronic excitations

A multiple‐analyser‐crystal spectrometer for non‐resonant inelastic X‐ray scattering spectroscopy installed at beamline ID16 of the European Synchrotron Radiation Facility is presented. Nine analyser crystals with bending radii R = 1 m measure spectra for five different momentum transfer values simultaneously. Using a two‐dimensional detector, the spectra given by all analysers can be treated individually. The spectrometer is based on a Rowland circle design with fixed Bragg angles of about 88°. The energy resolution can be chosen between 30–2000 meV with typical incident‐photon energies of 6–13 keV. The spectrometer is optimized for studies of valence and core electron excitations resolving both energy and momentum transfer.     

Measurements of Young’s and shear moduli of rail steel at elevated temperatures

The design and modelling of the buckling effect of Continuous Welded Rail (CWR) requires accurate material constants, especially at elevated temperatures. However, such material constants have rarely been found in literature. In this article, the Young’s moduli and shear moduli of rail steel at elevated temperatures are determined by a new sonic resonance method developed in our group. A network analyser is used to excite a sample hanged inside a furnace through a simple tweeter type speaker. The vibration signal is picked up by a Polytec OFV-5000 Laser Vibrometer and then transferred back to the network analyser. Resonance frequencies in both the flexural and torsional modes are measured, and the Young’s moduli and shear moduli are determined through the measured resonant frequencies. To validate the measured elastic constants, the measurements have been repeated by using the classic sonic resonance method. The comparisons of obtained moduli from the two methods show an excellent consistency of the results. In addition, the material elastic constants measured are validated by an ultrasound test based on a pulse-echo method and compared with previous published results at room temperature. The measured material data provides an invaluable reference for the design of CWR to avoid detrimental buckling failure.     

A preliminary study of pure metal surfaces using Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS)

A system is described which incorporates Auger spectroscopy (AES), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) in one UHV chamber. The system has been used to determine sensitivity factors for XPS for a number of pure metals. These factors are then compared with ion yields from surfaces using SIMS. By performing similar XPS measurements in another, more conventional, system, comparison has been made of the electron transmissions of the double-pass cylindrical analyser in the XPS (retarding) mode and of the hemispherical analyser.