Scanning Electron Microscope EM-30PLUS Operating Manual
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8 Alignment Operation
8.1 Summary of E-Gun Alignment
E-gun is equipped inside of EM-30PLUS equipment.
When there is the filament replacement, a change of acceleration voltage, or a sudden
change of Spot size, the e-gun alignment is needed.
Because the path of electron beam can vary due to the movement and contact of
equipment without the changes above, the e-gun alignment is needed.
The structure of e-gun in equipment is as follows.
The e-gun alignment is the process to align filament and electron beam in a straight line
with Spot size(d) opened to the utmost limit and find out the optimum point of Filament
current. Normally, as Spot size gets bigger, screen gets brighter, and vice versa. However, if
e-gun is not aligned properly, the change of brightness of screen appears differently even
when Spot size values vary and lifespan of filament can be reduced.
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