The most important differences between a transmission electron microscope and a scanning electron microscope are: Rather than the broad static beam used in TEM, the SEM beam is focused to a fine point and scans line by line over the sample surface in a rectangular raster pattern.
So, how is an image formed in a scanning electron microscope?
Scanning Electron Microscopy (SEM) An SEM image is formed by a beam of electrons focused to a few billionths of a meter that is swept across the surface of a sample in a series of stacked rows until a complete two dimensional pattern is formed.
How does SEM produce images?
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the sample's surface topography and composition.
How is an image formed in a transmission electron microscope?
In the process of forming the primary image the objective lens produces a diffraction pattern at its back focal plane. The primary image is the Fourier transform of the diffraction pattern. This two-step process forms the basis of image formation during high-resolution transmission electron microscopy (HRTEM).
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