FEI Quanta FEG 250, User'S Operation Manual

Page: 162 / 228

System Options: Optional Detectors
9-14
LOW-VOLTAGE HIGH-CONTRAST DETECTOR
LENS MOUNTED / RETRACTABLE (vCD)
This is a solid State detector ideal for low accelerating voltages down
to about 200 V. The diode has an active area of approximately
100 mm
2
and it is positioned directly above the sample (optimum WD
should be from 3.5 to 7 mm) to achieve maximum detection efficiency.
Therefore it causes some limitation in a tilt range (see below).
FIGURE 9-8 Lens Mounted / Retractable vCD
Caution!
The diode is sensitive to mechanical damage so the active area (shiny
diode) should never be touched.
The detector could be mounted on a retractable arm which can be
inserted between the lens and the sample and it is parked to pole
piece to reduce vibration.
Select the Detector Settings module / Detector list box / vCD or from
the Detectors menu.
Inserting and Retracting vCD / CBS Detector
Before insertion the retractable version of vCD / CBS detector, the
user needs to check the following conditions:
• Chamber is pumped to HiVac or LoVac condition.
• The Link Z to FWD procedure must be done, the WD must be
more than 3.5 mm and the Tilt must be from - 0,5° to + 0,5°.
If the above mentioned conditions are not fulfilled, the Insert button is
not active (a tooltip occurs under the mouse cursor).
By clicking the Insert button the dialogue appears asking a
confirmation of detector insertion. The Tilt and the Z-axis stage
movements are limited to the above mentioned values.
Retracting the detector is automaticall with the Stopping / Starting the
server or venting the chamber. Otherwise user can use the
Retract
button.
When the detector is retracted, the information text is displayed in
each quad which uses it.