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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. This opens the The Cantilever Tune Window.
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. Set the Amplitude Range to 4000 mV.
HINT: It may be useful to adjust the Channel 1 Data Scale if the peak appears to be too big or too small.
  1. 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. Continue to zoom in and center the peak until the peak coincides with the vertical center line. 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 resonant frequency can decrease during engage due to the short distance between the cantilever and the sample surface. Configure the drive at a frequency lower than the resonant frequency to avoid the possibility that the resonant frequency might shift below the drive frequency upon approach of the tip to the surface.

  1. Specify the Drive Amplitude after tuning the cantilever to its resonant frequency to control the height of the amplitude peak. The desired operating amplitude depends on the sample and other scanning conditions.
  1. Click Exit to close the Cantilever Tune dialog and leave the parameters unchanged.

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