Changing the Vacuum Mode
LV mode is generally used to observe and analyze non-conducting sample without
the need for a conductive coating (Au/Pd or C).
1.
Turn off the Beam, i.e. Click
2.
Click
Vac. Mode
A dialog box confirming the change of mode should appear.
.
3.
Click
OK
4.
When switching to LV mode, a Low Vacuum Control Dialog box appears.
.
5.
An operating pressure of
1 to 270 Pa
(2 torr) can be selected.
6.
When
HT Ready
re-appears, click it to restore the e-beam (
)
LV mode
can be used to look at and analyze uncoated non-conductive samples
without charging artifact and imaging problems. It can also be used to observe wet or
badly out-gassing samples, but this requires addition procedures (wet). In general,
use as low as pressure as possible that works for imaging the sample (1 to 10’s of Pa).
Again
BEIW
-
Shadow
mode provides secondary electron like images. Since the e-
beam will interact with the gas in the specimen chamber, increasing pressure will
result in a signal decrease and the resolution will get poorer. Also, longer working
distances generally will not work well in
LV mode
.
Starting with LV vacuum mode (sample is not suitable for HV vacuum mode)
Change mode to LV before pressing EVAC. Automatic gun alignment functions do not
function in LV mode. Strongly suggest verifying proper operation/alignment in normal
HV mode first (even if it is just on the stage, i.e. no sample)
Improving Depth of Focus or Obtaining Lower Magnifications
Move sample to a longer working distance.