扫描电子显微镜探头系统故障诊断和排除

本文介绍扫描电子显微镜探头系统的常见故障,分析了故障产生的原因,说明了排除故障的步骤。     

原子力显微镜在液相环境中的应用研究

简要介绍了原子力显微镜的工作原理 ,着重分析了液相探头的设计 ,并利用该探头进行了液相环境的样品表面形貌测量 ,给出了测量的图像。实验表明 ,该液相探头具有良好的液态环境扫描性能 ,图像稳定 ,分辨力高。     

GapLPE半导体材料的扫描电子显微镜研究

本文论术了用扫描电子显微镜ＧａＰＬＰＥ半导体材料，二次电子像用于分析样品的表面形貌     

基于形态分析的超声探头扫描子系统的设计研究

从形态分析的原理出发,结合超声探头的特点,列出了形态学矩阵,依据扫描系统的评价标准,得到管道检测机器人系统超声探头扫描子系统的最优设计方案,并给出了具体的设计参数。     

AMDEL载流分析仪的固态探头

澳大利亚矿物研究实验室(AMDEL)生产的载流分析仪,是一种利用放射性同位素沉入式探头进行矿桨或溶液元素品位分析的仪器,我国许多选矿厂在矿浆流道中使用了这种仪器。     

场发射扫描电子显微镜JSM-IT800(SHL)探测器和观察模式的设置

型号为JSM-IT800(SHL)场发射扫描电子显微镜是日本电子株式会社（JEOL）所推出的扫描电镜。针对不同类型样品的表征需求，该电镜配置有多个探头和多种观察模式。如果熟练掌握这些探头与观察模式的选择与设置方式，能充分发挥该款电子显微镜的优势并能提高样品表征的质量。本文介绍了该款电子显微镜的4种观察模式，并针对不同类型的探头和观察模式，选取具有代表性的扫描电子显微镜图片进行对比，总结探头选择和观察模式的规律，供操作人员和初学者参考。     

基于单片机的接触式液面检测系统

介绍一种应用于医疗仪器上的液面检测系统.该系统采用单针作为检测探头,基于电容法的电路结构,包括振荡电路、滤频电路、RC电路等.使用超低功耗单片机MSP430F2013作为主控芯片,用其高精度AD模块测量单针探头电容的变化来判断单针探头是否接触液面,同时采用移动平均算法消除温漂和外部干扰信号对检测结果的影响.本系统通过了实验的验证,已广泛应用于各种医疗仪器.     

便携式拉曼光谱仪的设计

研制了适合现场使用的便携式拉曼光谱仪。介绍了仪器的特点和组成、激光光源、拉曼光纤探头和CCD光纤光谱仪。     

光纤探头脉像仪的实验研究

本文介绍了采用光纤传感器的光纤探头式脉像仪的原理、仪器的结构，以及用其实际测试的结果。初步实验表明，该检测仪器能够精确、方便地测定脉像。     

过套管仪器井下探头结构分析及应用

从过套管电阻率测井原理出发,重点介绍了国外基于过套管测井原理的两种仪器,给出了井下探头主要结构,并对重点部件进行了结构分析,详细对比总结两种仪器优缺点,结合两种仪器的市场应用情况及所需实际井况,为选择合适的仪器提高测井效率降低生产成本提供参考。     

A novel pixellated solid‐state photon detector for enhancing the everhart–thornley detector

This article presents a pixellated solid‐state photon detector designed specifically to improve certain aspects of the existing Everhart–Thornley detector. The photon detector was constructed and fabricated in an Austriamicrosystems 0.35 µm complementary metal‐oxide‐semiconductor process technology. This integrated circuit consists of an array of high‐responsivity photodiodes coupled to corresponding low‐noise transimpedance amplifiers, a selector‐combiner circuit and a variable‐gain postamplifier. Simulated and experimental results show that the photon detector can achieve a maximum transimpedance gain of 170 dBΩ and minimum bandwidth of 3.6 MHz. It is able to detect signals with optical power as low as 10 nW and produces a minimum signal‐to‐noise ratio (SNR) of 24 dB regardless of gain configuration. The detector has been proven to be able to effectively select and combine signals from different pixels. The key advantages of this detector are smaller dimensions, higher cost effectiveness, lower voltage and power requirements and better integration. The photon detector supports pixel‐selection configurability which may improve overall SNR and also potentially generate images for different analyses. This work has contributed to the future research of system‐level integration of a pixellated solid‐state detector for secondary electron detection in the scanning electron microscope. Microsc. Res. Tech. 76:648–652, 2013. © 2013 Wiley Periodicals, Inc.     

Scintillation SE detector for variable pressure scanning electron microscopes

We present results obtained with a new scintillation detector of secondary electrons for the variable pressure scanning electron microscope. A detector design is based on the positioning of a single crystal scintillator within a scintillator chamber separated from the specimen chamber by two apertures. This solution enables us to decrease the pressure to several Pa in the scintillator chamber while the pressure in the specimen chamber reaches values of about 1000 Pa (7.5 Torr). Due to decreased pressure, we can apply a potential of the order of several kV to the scintillator, which is necessary for the detection of secondary electrons. Simultaneously, the two apertures at appropriate potentials of the order of several hundreds of volts create an electrostatic lens that allows electrons to pass from the specimen chamber to the scintillator chamber. Results indicate a promising utilization of this detector for a wide range of specimen observations.     

Use of backscattered electron detector arrays for forming backscattered electron images in the scanning electron microscope

The backscattered electron (BSE) signal in the scanning electron microscope (SEM) can be used in two different ways. The first is to give a BSE image from an area that is defined by the scanning of the electron beam (EB) over the surface of the specimen. The second is to use an array of small BSE detectors to give an electron backscattering pattern (EBSP) with crystallographic information from a single point. It is also possible to utilize the EBSP detector and computer-control system to give an image from an area on the specimen--for example, to show the orientations of the grains in a polycrystalline sample ("grain orientation imaging"). Some further possibilities based on some other ways for analyzing the output from an EBSP detector array, are described.     

Quality improvement of environmental secondary electron detector signal using helium gas in variable pressure scanning electron microscopy

The quality of the image signal obtained from the environmental secondary electron detector (ESED) employed in a variable pressure (VP) SEM can be dramatically improved by using helium gas. The signal-to-noise ratio (SNR) increases gradually in the range of the pressures that can be used in our modified SEM. This method is especially useful in low-voltage VP SEM as well as in a variety of SEM operating conditions, because helium gas can more or less maintain the amount of unscattered primary electrons. In order to measure the SNR precisely, a digital scan generator system for obtaining two images with identical views is employed as a precondition.     

A systematic investigation of the charging effect in scanning electron microscopy for metal nanostructures on insulating substrates

Scanning electron microscopy is perhaps the most important method for investigating and characterizing nanostructures. A well‐known challenge in scanning electron microscopy is the investigation of insulating materials. As insulating materials do not provide a path to ground they accumulate charge, evident as image drift and image distortions. In previous work, we have seen that sample charging in arrays of metal nanoparticles on glass substrates leads to a shrinkage effect, resulting in a measurement error in the nanoparticle dimension of up to 15% at 10 kV and a probe current of 80 ± 10 pA. In order to investigate this effect in detail, we have fabricated metal nanostructures on insulating borosilicate glass using electron beam lithography. Electron beam lithography allows us to tailor the design of our metal nanostructures and the area coverage. The measurements are carried out using two commonly available secondary electron detectors in scanning electron microscopes, namely, an InLens‐ and an Everhart–Thornley detector. We identify and discriminate several contributions to the effect by varying microscope settings, including the size of the aperture, the beam current, the working distance and the acceleration voltage. We image metal nanostructures of various sizes and geometries, investigating the influence of scan‐direction of the electron beam and secondary electron detector used for imaging. The relative measurement error, which we measure as high as 20% for some settings, is found to depend on the acceleration voltage and the type of secondary electron detector used for imaging. In particular, the Everhart–Thornley detectors lower sensitivity to SE₁ electrons increase the magnitude of the shrinkage of up to 10% relative to the InLens measurements. Finally, a method for estimating charge balance in insulating samples is presented.     

Measurement technique for the incident electron current in secondary electron detectors and its application in scanning electron microscopes.

A measurement technique for incident electron current in secondary electron (SE) detectors, especially the Everhart-Thornley (ET) detector, based on signal-to-noise ratio (SNR), which uses the histogram of a digital scanning electron microscope (SEM) image, is described. In this technique, primary electrons are directly incident on the ET detector. This technique for measuring the correlation between incident electron current and SNR is applicable to the other SE detectors. This correlation was applied to estimate the efficiency of the ET detector itself, to evaluate SEM image quality, and to measure the geometric SE collection efficiency and the SE yield. It was found that the geometric SE collection efficiency at each of the upper and lower detectors of a Hitachi S-4500 SEM was greater than 0.78 at all working distances.     

Imaging deep holes in structures with gaseous secondary electron detection in the environmental scanning electron microscope

The gaseous secondary electron detector (GSED) in the environmental scanning electron microscope (ESEM) permits collection of electron signals from deep inside blind holes in both conducting and insulating materials. The placement of the GSED as the final pressure-limiting aperture of the ESEM creates a situation of apparent illumination along the line of sight of the observer. In principle, any point struck by the primary beam can be imaged. Image quality depends on the depth of the hole. In brass, features at the bottom of a 1.5 mm diameter hole that was 8 mm deep were successfully imaged.     

Application of channel electron multipliers in an electron detector for low‐voltage scanning electron microscopy

An electron detector containing channel electron multipliers was built and tested in the range of low‐voltage scanning electron microscopy as a detector of topographic contrast. The detector can detect backscattered electrons or the sum of backscattered electrons and secondary electrons, with different amount of secondary electrons. As a backscattered electron detector it collects backscattered electrons emitted in a specific range of take‐off angles and in a large range of azimuth angles enabling to obtain large solid collection angle and high collection efficiency. Two arrangements with different channel electron multipliers were studied theoretically with the use of the Monte Carlo method and one of them was built and tested experimentally. To shorten breaks in operation, a vacuum box preventing channel electron multipliers from an exposure to air during specimen exchanges was built and placed in the microscope chamber. The box is opened during microscope observations and is moved to the side of the scanning electron microscope chamber and closed during air admission and evacuation cycles enabling storing channel electron multipliers under vacuum for the whole time. Experimental tests of the detector included assessment of the type of detected electrons (secondary or backscattered), checking the tilt contrast, imaging the spatial collection efficiency, measuring the noise coefficient and recording images of different specimens.     

Medipix 2 detector applied to low energy electron microscopy

Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.     

Review and outline of environmental SEM at present

The environmental scanning electron microscope (ESEM) allows the examination of specimens in a gaseous environment. It is based on an integration of efficient differential pumping with a new design of electron optics and detection systems. Backscattered, cathodoluminescence and X-ray detectors can be designed to fit and to perform optimally in the ESEM. The secondary electron signal can be detected with the gaseous detector device, which is a new multipurpose detector. Insulating, uncoated, wet and generally both treated or untreated specimens can be studied.