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Manual Cantilever Tuning

For Force Modulation applications or Fluid Imaging in TappingMode, it may be useful to tune the cantilever manually.

To access the manual tuning controls, click the Tune icon in the workflow toolbar or the Manual Tune button in the Tune Cantilever panel of the Setup view.
NOTE: More than one type of cantilever exists. Cantilevers can have different dimensions and different resonant frequencies. Certain parameter values, particularly the center frequency and the sweep width given in examples in the following procedure, apply to a particular cantilever type. Parameter values will vary depending on the actual cantilever used.
  1. In the Graph drop down list of the Cantilever Tune window, set the Drive Frequency parameter to a value near the center of the resonant frequencies range specified for the wafer. For example, if the frequency range is specified as 240–420 kHz, select a drive frequency of 330 kHz.
  2. Set the Drive Amplitude to 200 mV.
  3. Set the Sweep Width to the same value as the Center Frequency. The Sweep Width must be large enough to cover the frequency range specified for the wafer.
  4. Zero the setpoint.
  5. Set the Amplitude Range to 4000 mV.
  6. Center the peak on the frequency sweep plot shown using the Zoom In and Offset commands after identifying the maximum amplitude peak with the lowest frequency in the frequency response plot.
NOTE: Activate the Offset radio button to set the center frequency equal to the cursor position and shift the plot. Activate the Zoom In radio button and click and drag to define a region on the plot, decreasing the sweep width and shifting the center frequency value.
  1. Increase the Amplitude Setpoint until the peak appears.
  2. Continue to zoom in and center the peak until the peak coincides with the vertical center line within 10 Hz. The value displayed for center frequency is now used as the resonant frequency of the cantilever.
NOTE: For the system to work well in TappingMode, the drive frequency must be at or below the peak in the resonance plot. The center frequency can decrease to the point where the oscillation amplitude reaches 90 percent of the maximum value. Operate at a frequency lower than the resonant frequency to avoid shifting the resonant frequency upon approach of the tip to the surface.

  1. Specify the RMS amplitude after tuning the cantilever to its resonant frequency. The desired operating amplitude depends on the sample and other scanning conditions.
  1. Click Auto Tune. The parameters set in the Cantilever Tune control panel appear in the Realtime control panel.
  2. Click Exit to close the Cantilever Tune dialog and leave the parameters unchanged.

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