Keysight 5500 SPM
User’s Guide
6
AC Modes
In AC Mode, introduced in
sinusoidal voltage is applied to a piezo element or magnetic coil in the
nose assembly or sample plate. The piezo or magnetic coil causes the
probe tip to oscillate, typically at or near one of its resonance
frequencies, and the tip is brought close enough to the sample surface
that it taps gently on the surface. The tip is then raster-scanned over the
region of interest while the amplitude of oscillation is monitored to
control the height of the tip above the sample. Through this method,
lateral forces on the tip are virtually eliminated, enabling higher
resolution imaging than is possible with Contact Mode.
The process for imaging in AC Mode is similar to that of Contact Mode,
with one additional step: the cantilever must be tuned to determine the
resonant frequency.
There are two methods for providing the oscillation: Acoustic (AAC)
and Magnetic (MAC). Both AAC and MAC Modes require the
additional AC/MAC Mode or AC/MAC Mode III controller.
The AC/MAC mode modules utilize “lock-in amplifier” technology to
precisely determine the oscillation frequency, amplitude and phase
response of the cantilever, resulting in excellent force regulation and
NOTE
This chapter references material in
review and understand
before continuing with AC Mode.