Microscope Descriptions

Electron Microscopes

Two kinds of electron microscopes were used to produce the images on this website. The vast majority of the images were taken with the scanning electron microscope or (SEM). This electron microscope uses a narrow beam of electrons produced from a tungsten filament that moves over the surface of the sample in a rectangular raster pattern emitting signals generated from the sample surface. These signals generate a wealth of information about the sample and can even be used to determine its chemical composition. The signals generally used for imaging are the low energy or secondary electrons and high energy backscattered electrons which are collected by one or more detectors and used to generate a detailed topographic map of the sample surface. This results in a black and white image of the specimen surface. The color in the image is purely arbitrary and was done using photoshop. 

The second type of electron microscope is the transmission electron microscope  (TEM). This type of microscope uses the electron beam from a tungsten filament to go through a very thin slice of preserved biological tissue and record the interior ultrastructure of a cell.  The TEM can also view a  whole sample like a virus which is naturally small enough for the electron beam to pass through to produce high resolution images not possible with a light microscope. Since electrons have much shorter wavelengths than the photons used in light microscopes, the resolution (ability to see fine detail) is greatly improved. All of the viruses images except for one were taken with the TEM. All other images on this website were recorded using the SEM.