Instruction manual

Fluid Operation
General Fluid Operation
132 MultiMode SPM Instruction Manual Rev. B
8.2.7 Adjust the Detector Offsets and Setpoint (Contact Mode)
Adjust the detector mirror adjustment screws:
• In Contact Mode (i.e., Other Controls > Microscope mode set to Contact and
Feedback Controls > SPM Feedback set to Deflection), to achieve a vertical
deflection signal of roughly -1.0V. Set the Feedback Controls > Deflection Setpoint to
0V to begin.
• The difference between the vertical deflection signal before engaging and the setpoint
determines the amount of force that the probe applies to the sample.
• Typically, samples are softer in liquid than in air. Before engaging, verify that there is
not so large a difference between the setpoint and the vertical deflection signal as to
damage the sample.
• Verify reasonable values for scan parameters (e.g., Scan rate, Scan size, Integral gain
and Proportional gain).
• Once engaged, reduce the setpoint to minimize the tracking force.
8.2.8 Engage the Surface
1. Using the Motor down switch (and coarse adjustment screws if not using a vertical engage
scanner), lower the tip until it is just above the level of the sample surface.
• The Motor down switch is located on the MultiMode base.
• Watch the engagement closely through the 25× magnifier or using the vertical optical
microscope.
2. In the Real Time > Motor menu, click Engage, or click the Engage icon.
• The motor begins to move the AFM head and probe down to the sample.
• When the tip reaches the surface, the system should automatically stop, beep, and begin
to image the sample.
• In Contact Mode, if the system engages immediately or before the tip reaches the
surface, try increasing the Setpoint approximately 2.0V, then repeat this step.
8.2.9 Adjust Scan Parameters (Contact Mode)
1. Once engaged, adjust the scan parameters to obtain the best image.
Note: This procedure is similar to operation in air, except that samples are often softer
in fluid. Adjusting the applied force can be critical.