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Description of the Microscope
11
MIRA3 FEG-SEM
FIELD Mode
The FIELD mode utilizes the intermediate lens IML for the electron beam focusing while the
objective OBJ is off.
Characteristics:
large field of view
high depth of focus
worse resolution
The beam aperture is very small and the depth of focus is usually
higher than the field of view. As the objective OBJ is off in this case,
it does not affect the middle beam and thus does not need to pass
near the centre of the objective OBJ. The position of the pivot point
of scanning is optimized according to the field of view. The
centering coils IML center the supplemental intermediate lens IML
to avoid image movement during focusing. The DC component
of the scanning coils is set up so that no image shift occurs
if switched from RESOLUTION mode to FIELD mode.
The disadvantage of this mode is a bigger spot size; the maximum
magnification used is a few thousand. The mode is used for the
searching of the parts of the specimen to be examined.
Содержание MIRA3
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