Instructions for Use of the Scanning Electron Microscope (SEM)

Aligning the Gun

To maximize resolution (SEM) and xray counts (EDS), the electron beam must be centered.

  1. Turn on the beam and bring up the Control Panel (Ctrl-G). Adjust the following parameters to set up for gun alignment:
    • Detectors: Auto BC = BC
    • Gun: Spot = 400
    • Gun: EHT Target = 20kV
    • Scanning: Scan speed = 2
  2. In main menu, go to Beam > Gun Align.
  3. Select Emission to look at the image of the beam pattern. The image should be a solid elipse, centered on the green crosshairs. (If the elipse isn�t solid, this will be adjusted when you saturate the filament.)
  4. If the beam isn�t centered, select Auto Align. Check the alignment at the end of the process by selecting Emission again.
  5. You must check filament saturation after any gun alignment.