Stereo Scan 440 - DCU

Each zone has its individual detector assignment, so in quad mode as many as
four different detectors could be displayed. The detector controlled by the signal
level functions is detemlined by the current zone, although if that detector is
assigned to more than one zone then more than one part of the quad image may
be affected.
~
It is possible to set up different auto signal level controls for different
zones. If there is a conflict between two zones which have the same detector
assigned to them, then the first zone with that detector will take precedence.
Collector Bias
The Collector Bias can be assigned to mouse control from the option in the
Detectors menu. It can be varied in the range -250V to +4OOV. For nonnal
operation of the secondary electron detector this value should be set to maximum.
Four Quadrant BSD
The four quadrant back scattered detector has a configuration panel dedicated to
it, which can be selected from the Detectors menu. Each quadrant of the detector
can be in one of three states (Off, Normal or Invert). When normal the signal
from that quadrant is added to the total signal, when inverted the signal is
subtracted. Clicking on the quadrant fields allows each one to be configured as
desired.
Qf
Notmal
02
NotmaJ
01
kIVett
02
krveIt
03
Nom8J
04
NomIaI
03
Normal
04
NomIai
Cof1f)OSIkJn
T~y
FIgUre 2.5
Two predefined configurations of quadrants are available to set the detector to
give best perfonnance for composition (Compo), that is atomic number contrast,
or surface topography (Topo). Selecting these predefined configurations will set
up the detector quadrants according to Figure 2.5.
Stereoscan 440 Operator Manual