20 November 2010, R. Ubic
7
Filament Ramping
Make sure the
Normal Setup
button is selected in the Filament Control Speed.
The filament should be set to ramp to some percentage (typically 60% - 70%) less than
the maximum limit. Do not alter this number or the filament maximum limit.
Press the filament ON button in the High Voltage Control window (or the
Beam
button
on the top left of the left-hand control panel).
The Filament window appears. While it is open you cannot access any other windows.
Alignment Procedure
Finding the beam
The last user should have left the microscope at a magnification of about 50k and with
all the apertures out. If you can't find the beam, the most likely reason is that your
sample is in the way. Try moving it around. DO NOT move apertures or use beam shift
knobs to find the beam!
If you can't find the beam, try:
1. Check that the beam current has reached its normal value (½ kV ± 10%).
2. Check that all the apertures are out.
3. Check that the spot size is set to 1 (use
SPOT SIZE
knob on left-hand panel).
4. Decrease the magnification and spread the beam.
5. Go to
LOW MAG
mode (button on right-hand panel) and spread the beam with
the
BRIGHTNESS
knob (on left-hand panel).
6. Move your sample around with the trackball.
7. If you still can't find it, turn off the filament and remove the sample holder to the
park position. Turn on the filament again and repeat the above steps to find the
beam. If you find it, center it, then shut off the filament, re-insert your sample,
and begin again.
8. Try loading a previous alignment (Maintenance - Alignment - Load Alignment
File)
9. If you still can't find the beam, get assistance from Rick Ubic.
Gun Alignment
Find a hole in the sample.
For initial alignment, set the
α
-selector to 3. In general, for magnifications less than
≈
100k,
α
= 3 is appropriate. Setting 2 is recommended for magnifications above 100k,
and setting 1 is recommended for magnifications of 400k and above.
