15.
Set the Signal to
SEI
, if not already
(You can change it to
BEIW
, if desired later).
16.
Click the
HT Ready
icon to turn on the High Voltage, now should be
Some intensity should be seen in the image window. If not press
View
and
ACB
.
ACB
takes several seconds to run. Something should be visible on the
screen now.
17.
Click the
Gun
icon
. The electron gun and alignment dialog appears.
There are a couple of options at this point depending on skill level, needs, etc.
Basically you need to check gun alignment and then filament saturation.
Recommended Procedure:
Manually perform this task. It only takes a minute and
will insure optimized operation and best images. Note: We do NOT use Auto filament
heating or Auto Gun Control. We found the use of these seem to shorten filament life
significantly.
a.
Select an area on the sample or sample holder that has reasonably
homogeneous brightness at moderate magnification (1-5 kx)
b.
Adjust Tilt X and Y for maximum average image brightness at a low Spot
Size setting (<=20) by iteration.
c.
Adjust Shift X and Y for maximum average image brightness at a high Spot
Size setting (=>60).
ACB
or manual adjustment of brightness/contrast will
likely be needed as the image brightness will usually saturate. If intensity
disappears before reaching Spot Size 60, adjust shifts at highest spot size
you still have an image, then increase to above 60 and adjust again. Again
iterate controls to optimize.
d.
Steps b and c can be iterated to optimize alignment. This is usually not
necessary unless large adjustments in the first pass were required.
