FEI Quanta FEG 250, User'S Operation Manual

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Software Control: xT microscope Control Software
4-12
Full Frame (Ctrl + M)
is the default scanning mode, typical for navigation and imaging.
Spot (Ctrl + K)
In this mode, the image pauses and the scanning is switched off. The
actual beam position is represented by a green cross in all paused
electron images. You can move the cross or click anywhere around
the screen to change its position.
Line
In this mode, the green horizontal line is displayed in all paused
electron images. The beam scans along this line. You can move it or
click anywhere around the screen to change its position.
External
switches to activate external control of the scanning system, such as
beam control from an EDX system. The external scanning mode is
indicated by the External label displayed in the upper right corner of all
imaging quads.
Beam Blank (Ctrl + B)
deflects the beam off axis high in the column and protects the
specimen from unnecessary exposure. When the beam is blanked the
toolbar icon is highlighted. Clicking it releases the blanker and returns
the beam to scan the specimen.
Slow / Fast Scan (Ctrl + Shift + , / .)
brings the scanning condition to the preset
Slow (left icon) / Fast (right icon) scan value (see the
Preferences… /
Scanning tab). When either of the two presets are active or selected
the respective icon is highlighted.
Slower / Faster Scan (Ctrl + , / .)
sets the scanning condition to the next preset Slower (left arrow) /
Faster (right arrow) value (see the
Preferences… / Scanning tab).
The spinner box shows the actual dwell time, but does not enable to
change or select directly its value - the values are changed one step
up or down (see Preferences).
Mains Lock
When ticked, the scanning (line or frame sawtooth signal) is
synchronized with the mains AC oscillation. This greatly diminishes
blurring and jittering of the electron image resulting in smooth image
edges at higher magnifications and slow scan conditions. It has no
influence on fast scan images.
Line Integration
With this function each line scan is repeated several times (from 2 to
100) before proceeding to the next line. Signal data collected from
these passes are integrated and displayed as an actual image line.
This imaging method reduces sample charging (in comparison with
single pass with longer dwell time) and improves overall image quality.
Scan Interlacing
This function splits an imaging area into blocks defined by the number
of lines (from 2 to 8). In the first instance the first line of each block is
scanned, then the second one etc. This imaging method significantly
reduces sample charging.