Contact AFM Mode
Preparation Prior to Imaging
Rev. B
MultiMode SPM Instruction Manual
89
Figure 6.1b
Laser Adjustment Knobs—Top View
6.1.2 Signal Settings
In Contact AFM Mode, the vertical de
fl
ection (
Vert De
fl
.
) signal is used to provide the dynamic
feedback signal for surface height tracking. The horizontal de
fl
ection (
Horiz De
fl
.
) is only used for
lateral force measurements in Contact Mode LFM. When disengaged in Contact AFM Mode and
preparing for engagement, set the detector
Vert De
fl
.
adjustment to between
-3.0
and
-2.0V
for
(SiNi cantilevers) or
-0.5
and
-1.0
(Si cantilevers). If performing LFM, set
Horiz De
fl
.
to
-1.0
to
+1.0V.
This is recommended for a 0.0V
Setpoint.
Note:
Large offsets are not recommended between engage and disengage (2V) with
etched silicon cantilevers in Contact Mode (450µm long only) because
breakage is likely. With etched silicon contact probes, it may be necessary to
reduce the offset between engage and disengage to a value of 1.0—1.5V. The
large difference is recommended for
fi
rst-time use of silicon nitride cantilevers.
The difference between the vertical de
fl
ection before engage and the setpoint is related to the force.
A larger, more positive setpoint voltage results in a larger contact force.
Horizontal Adj.
Ve
rtical.
Laser Spot
