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Microscopy

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Use of the microscope is an invaluable tool when studying small particles. Different microscopes yield different information, but all are useful to help classify and identify small particles or mixture of small particles. Download a printable version of the Microscopy services offered..

We have available the following Microscopic capabilites:

  • Variety of Optical Light Microscopes
  • SEM - Scanning Electron Microscopy
  • TEM - Transmission Electron Microscopy
  • EDS - Energy Dispersive X-Ray Spectroscopy
  • micro FTIR - Fourier Transform Infrared Spectroscopy
  • SWLIM - Scanning White Light Interference Microscopy
  • Confocal Raman Microscopy/Spectroscopy

Light Microscopy
We see objects in our environment every day by observing the light that is reflected from them. We note their shape, color and how they react to other variables such as wind and weather. These observations help us navigate through our day.

The classification and identification of small particles begins with observation of the particle through a microscope using a combination of transmitted and reflected light. The light microscopist adds several degrees of control to his observations. He immerses the particles he is to characterize in a liquid of known refractive index and records the color and contrast of the particle as he applies polarized light and measures the optical properties of the particle. Many times there are sufficient optical characteristics present to identify the particle. Particles photographed through the microscope can be measured and displayed for a report or an advertisement especially when the particles' harbor unique characteristics.

Scanning Electron Microscopy (SEM)


When a second test is needed to confirm an observation made by light microscopy, or when a particle is opaque, the particle can be imaged and analyzed using electrons instead of light. The immediate difference is that the images produced by the SEM are gray scale with no color (unless they are falsely colored at a later time). The images reveal a depth of field and detail that is superior to light microscopy with an added bonus that as electrons are bombarding the sample, x-rays are produced that are representative of the elements present in the sample. So adding an energy dispersive x-ray spectrometer (EDS) enables the microscopist to determine the elements present in the sample while imaging the sample.

Transmission Electron Microscopy (TEM)
Particles too small to be analyzed and imaged by light microscopy or scanning electron microscopy must be observed and analyzed in the transmission electron microscope. For thin samples or samples that can be made thin, TEM imaging techniques can reveal the crystalline structure of the particle as well as its elemental composition (EDS). Clays, pigment particles, thin films and other nanometer-sized particles can be analyzed and identified in the TEM. Some materials such as thin mineral fibers, clay particles, and soot need very little preparation to be analyzed. Other materials require considerable sample preparation prior to analysis.

Micro-Fourier Transform Infrared Spectroscopy (FTIR)
Particles that are plastic (easily deformed) can be characterized using a microscope that uses reflected and transmitted infrared light. Polymeric materials that need to be characterized and identified can be prepared for FTIR. The resulting infrared spectrum can be compared to thousands of reference spectra to determine the type of polymer. Manufacturing facilities that occasionally have undesirable particles appear in their finished products will keep a reference library of infrared spectra that identify the materials used in their processes to aid in the characterization of customer returns.


Scanning White Light Interference Microscopy (SWLIM)

The characterization of surfaces requires a slightly different approach using a microscope that can measure surface roughness and provide a three-dimensional image of the surface. This microscope utilizes reflected white light while scanning through focus to create a three-dimensional data set from which surface roughness parameters can be calculated. Unlike stylus profilometry, SWLIM is a non-contact technique with little or no sample preparation required.