Operating Procedures:
Obtaining an Image
5-5
SELECTING VACUUM MODE
When a specimen and appropriate detector(s) are inserted correctly,
close the specimen chamber door and continue the procedure (see
above):
6.
In
Vacuum
module, select the
High Vacuum
/
Low Vacuum
/
ESEM
radio button.
7.
For Low Vacuum / ESEM modes use water or select the desired
gas environment (option) from the drop down list box and the
target pressure that the system pumps to in the
Chamber
Pressure
adjuster.
8.
In the
Vacuum
module click on the
Pump
button. While pumping,
choose the highest specimen point and bring it to the 10 mm WD
(yellow line in an optical quad).
Note:
Under normal operation, the system knows the
PLA size
for the
detector installed. This allows the system to set automatic
pressure range limits for the aperture installed, thus avoiding
vacuum errors when setting chamber pressure. In some cases the
user is prompted for the PLA size by the PLA Configuration
dialogue.
WA R N I N G !
The system can be damaged by using the Low Vacuum / ESEM
mode without an appropriate PLA. Do not select a PLA Cone
which is not actually mounted onto the objective pole piece.
9.
Wait for the vacuum status
Pumped
, represented in the
Status
module at the base of the page by the green icon.
Low Vacuum and ESEM Modes
Which one of these modes is used depends on either the detector
installed or some special conditions (working with the cooling stage
implies ESEM mode for instance).
Purging
The microscope provides automatic sequencing for purging the
specimen chamber according to the settings of
Purge Mode
in the
Preferences… / ESEM
tab. There may be certain applications (e.g.,
working with a sensitive sample) where the operator needs to change
the purging parameters:
•
Select
No Purge
when purging the specimen chamber is not
desired. The chamber goes to the set pressure directly and the gas
mixture in the chamber slowly changes to the selected gas type.
•
Select
Automatic
to use pre-defined values for
Minimum /
Maximum Pressure
and
Number of cycles
. The
Purge Settings
displays the actual default values.
•
Select
Custom
to change the
Minimum / Maximum Pressure
and
the
Number of cycles
manually using the
Custom
Edit
boxes.
Caution:
The maximum allowed pressure is 200 Pa (1.5 Torr) for all actually
available PLA Cones.
Summary of Contents for Quanta FEG 250
Page 8: ...C vi...
Page 28: ...System Operation Quanta FEG System States 3 10...
Page 108: ...Alignments 1 Gun Alignment 6 6...
Page 114: ...Alignments 154 Water Bottle Venting 6 12 154 Water Bottle Venting...
Page 152: ...System Options Automatic Aperture System 9 4...
Page 154: ...System Options Nav Cam 9 6 401 NAV CAM AUTOBRIGHTNESS...
Page 177: ...System Options Cooling Stage Waterless Cooling Stage 9 29...
