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Setting scanning parameters
5-28
TMPM5200-2
Alt
e parameters differ depending upon the specimen and the purpose of
obse
Scan Size
Click
highlighted, enter 1.000 (1 um) using the keyboard and press the Tab key to
Before carrying out an approach, set the scanning parameters required for observation.
hough thes
rvation, you usually set the parameters as follows.
on the Scan Size selection box. When the numerical value is
finalize the input. Or, click on the
button in the Scan Size selection box
and select a numerical value near 1 000 nm.
The maximum scan
ning range depends on the scanner installed. In actual practice,
the scanning area should be changed to the region you want to observe.
Clock/ms
C
lick on the
button in the Clock/ms selection box and select 100.00 us.
This is the parameter that determines the scan speed. Naturally, this parameter
should be changed according to the observation area and the unevenness of the
specimen surface.
Filter/Hz
Click on the
button in the Filter/Hz selection box and select 1.0 from the
p
ull-down menu.
Filter/Hz is the parameter that determines the response speed of the feedback circuit.
The larger the set value is, the faster the response speed becomes, thus producing a
sharp image. But the feedback circuit easily oscillates. As a general rule to follow,
set the highest speed at which the feedback circuit does not oscillate while watching
the image during scanning.
Loop Gain
Click on the
button in the Loop Gain selection box and select 8 from the
pull-down menu.
e gain of the feedback circuit. The larger the set value is,
The setting determines th
the higher the response gain becomes, thus obtaining a good image from an uneven
specimen surface, but the feedback circuit easily oscillates.
