Scanning Electron Microscope (SEM)

An instrument which uses a rastered electron beam to produce a variety of imaging modes from rough and polished samples.

Energy Dispersive X-Ray Spectrometer (EDS or EDX)

An instrument attached to an electron beam instrument used to detect and analyze x-rays emitted from the sample surface when impinged upon by the primary electron beam.

Secondary Electron Image (SE)

SEM image depicting surface topography

Backscattered Electron Image (BS)

Grey level intensity related to average atomic number

Cathodoluminescence (CL) Image

Image based upon photons emitted from the sample

X-Ray Maps

Elemental distribution presented as a concentration of dots where pre-selected element(s) present

• Cambridge S-200/Oxford EDS

  The major instruments in this system are the Cambridge Instruments S-200 scanning electron microscope with the Oxford XP3 pulse processor, x-ray microanalyser.

  • The SEM is equipped with a stage motorized in the X, Y and Z axes which can be controlled manually using a joystick, or externally by software.
  • The electron beam can be generated either by a standard tungsten hairpin filament or high brightness LaB6 cathode.
  • A quadrant design solid state backscattered electron detector is used for atomic number contrast imaging.
  • Cathodoluminescence (CL) detector with imaging and spectral CL designed by Electron Optic Services.
  • The S-200 uses 4pi software on a MAC based computer for digital capture and image transfer
  • The Oxford EDS can display a spectrum of elements from Boron to Uranium.
  • Digital x-ray mapping software by 4pi Analysis Inc, is capable of acquiring any number of discrete elemental maps simultaneously, using a resolution up to 1024x1024 and a user determined dwell time per pixel.
• Cambridge S-360/Link eXL-II

  The SEM from Leica Cambridge, a Stereoscan 360, is fully integrated with an Oxford Instruments (Link) eXL-II energy dispersive x-ray microanalyser. Key features of these instruments are described below.

• The Cambridge Stereoscan 360 is equipped with a fully automated stage, with a maximum travel of 100 mm in the X and Y axes, and 50 mm in the Z axis. In addition to all of the features of the S-200 this instrument has the following capabilities:
  • High resolution digital capture and storage of SEM images using the PC based Orion software. Capture and store images at 2992x2272 resolution in tiff or jpeg format.
  • Once files are captured digitally onto the PC they can be imported into Photoshop or other image based programs for further processing and manipulation.
  • Dynamic anaglyph stereo imaging, allowing 3-D viewing and distance measurements in the third dimension.
  • Storage of stage positions, allowing the user to return to any preselected position.
  • Complete integration with the EDS system for image and x-ray analysis.
  • Cathodoluminescence (CL) Imaging. When certain specimens are irradiated with electrons, they emit photons in the visible and infra-red spectrum. The cathodoluminescence system detects light from the specimen, instead of the normal secondary and backscattered electrons. The spectral response of this CL system is 350 to 850 nanometers.

• The Oxford Instruments (Link) eXL-II energy dispersive x-ray analyser has the following major features:
  • High resolution, low element x-ray detector capable of detecting down to boron.
  • External control of the SEM for full automation and image analysis applications.
  • Feature detection and classification which integrates four discrete software programs, including automation of the electron beam and motorized stage of the SEM. This application is used to characterize a sample by classifying features by elemental composition (up to 32 classes per study) and geometric measurements. The x-ray analyser utilizes the backscattered electron signal to detect features, the brightness of which falls within user selected grey level thresholds (0-255). An element file is established to include all elements of interest, after which standards are analyzed to derive a chemical classification file. This chemical classification file is then used by the automation software to categorize all detected and analyzed features. This application is referred to as feature analysis as it goes beyond the strictly geometric measurements of standard image analysis techniques.

• SEM images on the S360 can also be viewed in stereo. When producing stereo images directly from the SEM hard copies can be made by laser or ink-jet printer. Either format can be examined on a stereo viewer. In addition, quantitative measurements can be made of any feature, regardless of orientation.
• A second type of stereo imaging, termed anaglyph stereo is also possible. In this case images of differing tilt angles are transferred to the x-ray analyser, where they are displayed as superimposed red and green images. They are then viewed in stereo using matched red/green filter glasses. Included in the stereo software is the provision for distance measuring of any feature, regardless of orientation. Contour maps can also be produced.
• The S-360 SEM has the additional capability of dynamic stereo, which permits viewing of live stereo images. One of the major advantages of this system is the ability to produce depth measurements on the fly. Hard copies can be printed or saved as digital images to view on a PC.

All images are stored in digital format. They can be viewed and processed using a wide variety of imaging software for both PC and Mac platforms. Hard copies of images can be produced directly from the digital image by way of printing to a laser or injet printer.