FEI Quanta FEG 250, Руководство пользователя

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System Options: Optional Detectors
9-9
SCANNING TRANSMISSION ELECTRONS
MICROSCOPY DETECTOR (STEM I)
The STEM I is a two segment solid-state diode mounted underneath
the STEM I holder. It can be used at any available working distance
(preferably close to the lens for high resolution) or at the eucentric
position for simultaneous use of the EDX. It works best at a slow scan
conditions.
The mounting pin below the detector locates into the standard conical
single stub mount. The detector is connected to an SSD pre-amplifier
input board.
Note:
When the STEM I detector is mounted to the chamber, stage rotation
and tilt are locked automatically for the safety. It is possible to unlock
these stage movements manually, but beware of possible detector
cable damage while rotating or tilting the stage.
FIGURE 9-4 STEM I DETECTOR
Settings for STEM I Detector
The detector segments A (left) and B (right) can be switched
independently, enabling the bright field (BF) or dark field (DF) contrast
mode.
The STEM I holder has 8 positions for TEM sample grids. The
following table refers to the positions numbering and their related
capabilities.
The A+B condition (default) can be used for the first time since the
entire detector is working, which facilitates to get an image. To switch
BF / DF choose
Segment A / B in the Detector Settings module.
Choosing A-B gives a negative image that although will not be used
frequently may highlight features by contrast not easily seen
otherwise.
TABLE 9-1 STEM I HOLDER POSITIONS
Grid Position Observation Mode and Diode switching
1D and 5D The object is left / right of the segment separator:
Segment A gives BF / DF
Segment B gives DF / BF
2,3,4 BF – use Segment B only
6,7,8 BF – use Segment A only