Contact AFM Mode
Preparation Prior to Imaging
90
MultiMode SPM Instruction Manual
Rev. B
6.1.3 Adjust tip height above sample surface
Next, use the adjustment screws to adjust the tip height just above the sample surface. The
magni
fi
er can be used to monitor the tip while this is done. The coarse adjustment screws (if so
equipped) are located in front and may be used to make gross adjustments. The tip should be
positioned just high enough to reach the surface when engaged, but not so low as to risk crashing
into it. Use the motorized screw to ensure the head is reasonably level. (This is not a problem on
single-screw scanners.)
One method employed to adjust the height of silicon nitride tips on noncritical samples is to very
slowly lower the tip using the adjustment screws until a sudden change is noted on the sum display
of the MultiMode base. Most silicon nitride cantilevers are
fl
exible and, if lowered slowly and
carefully, may be gently touched to the surface without damage to either the tip or the surface.
Watch for the change on the elliptical sum signal display! When the sum signal change is noted,
stop lowering immediately. The
Tip Up
switch may then be toggled brie
fl
y to lift the tip just above
the surface (the sum signal should resume its normal value). This method works well on samples
which are not delicate and which can be imaged without concern for damage.
6.1.4 Position Tip with OMV
Focus the OMV on the sample, then increase the OMV focus until the sample is just out of focus.
Lower the tip until the sample is back in focus.
