e.
Manually check filament saturation. This is best done at a higher spot size
setting (40-60) and a high contrast setting. Click the Filament Heating down
arrow (left side of slider control) several times until you see the average
brightness decrease somewhat. Click the Filament Heating up arrow one
step at a time while noting the change in brightness.
The slider might fully
overlap and slightly past (<1mm) the left edge of the orange bar for new
filaments. It should never be set higher!
The average brightness should
increase with each step but the change between steps decreases. At the step
where there is virtually no perceptible increase, click the down arrow two-
three times. There should be a very slight decrease in average brightness.
The filament is now properly saturated. Note: If brightness decreases after
going through a maximum (before beginning of orange indicator), the gun
tilt/shifts are misaligned. This is usually because the filament was
significantly under saturated when you started. Restart the procedure, with
the right edge of the slider lined up with the orange bar.
Quick and Simple Modification
:
Simplified procedure, especially useful, where you do not want to expose
sample to high probe currents. Works well when starting point is correct or
almost correct.
a.
Just adjust both Tilt X and Y and Shift X and Y at a selected spot size
setting (the value you’re going to use) for maximum average brightness. A
noisy image (low spot size values), however, makes this more difficult. You
could increase the averaging in the scans setup dialog to decrease the noise
but remember the response time will be slower.
b.
Perform step e above.
Note:
Auto Alignment (Auto
button in Alignment box
)
may be run at any time but is
usually not necessary (manual alignment is more reliable and just as fast to do). When
