Instruction manual

Magnetic Force (MFM) Imaging
Installation of the Extender Electronics Modules
232 MultiMode SPM Instruction Manual Rev. B
13.2.2 Frequency Modulation
With the Basic Extender Module, it may be desirable to use frequency modulation. This activates a
feedback loop which modulates the Drive Frequency to keep the cantilever’s phase lag at 90
degrees relative to the drive, corresponding to resonance. The frequency Data Type displays the
resulting shift in Drive Frequency in Hz, and gives the most direct, quantitative image of force
gradients.
To enable frequency modulation, follow the procedure above for obtaining an MFM image with
phase detection. In the Interleave Controls panel set the Input Feedback to Frequency and turn it
on by selecting the bullet next to the parameter (the bullet will turn from gray to green). Switch the
Channel 2 image Data type to Frequency. Try a Data Scale (frequency shift) of approximately
10Hz. Select Other Controls, then adjust the frequency modulation gains. A good starting point is
to set both frequency modulation Integral gain and Proportional gain to 50 for a Basic Extender,
and 0.6 for a Quadrex Extender or NanoScope IV. As with the topography gains, the scan can be
optimized by increasing the gains to maximize feedback response, but not so high that oscillation
sets in.
13.3 Installation of the Extender Electronics Modules
13.3.1 Basic Extender
For MultiMode systems, the Basic Extender is installed using a 37-to-37 pin ribbon cable between
the NanoScope III or IIIA SPM controller and the Basic Extender Module, and a 37-to-25 pin
ribbon cable from the Basic Extender to the microscope. The hardware change consists of replacing
a circuit board in the base of the microscope (this may be done by either the customer or a factory
representative). Detailed installation instructions are provided with the new hardware when
shipped. For more information, contact Veeco.
The Basic Extender box is equipped with a slider switch for switching internal electronics between
Dimension-series and MultiMode SPM signals. This switch may be accessed through a hole on the
underside of the box. In the drawing below, the switch is set to “MultiMode.”
For MultiMode SPMs, it should always be set to “MultiMode.” Use a pencil to access the switch
through the hole.
Note: This switch is not required for Quadrex Extender use.
Dimension
MultiMode