Modes; Laser Align; Tune Frequency - AFM Workshop LS-AFM User Manual

3.2.1.2 Modes

There are two scanning modes: Vibrating mode and Non-Vibrating (contact) mode. The
modes are selected with the Scan Mode button. When Vibrating mode is selected, the fre-
quency sweep window is activated. When Non-Vibrating mode is selected, the frequency
sweep window is deactivated.

3.2.1.3 Laser Align

The position of the laser on the four-quadrant photo-detector is presented numerically and
visually in the Laser Align window. These two indicators are both updated in real time and
are used for aligning the light lever. There is a switch for turning the laser On and Off. This
switch will automatically turn the laser off after the system has been inactive for a certain
length of time.
NOTE: After the TT-2 AFM light lever is set up for the first time (see Appendix
A.6), the thumb screws used for laser alignment should not need to be turned
more than a few turns.

3.2.1.4 Tune Frequency

The Tune Frequency window is used for selecting the optimal conditions for producing vibrat-
ing-mode images. There are two oscilloscope windows: the upper window shows the ampli-
tude of the probe's vibration, while the lower window shows the phase between the drive
frequency and the measured frequency. The variable controls are:
1. Amplitude and Phase sliders: Adjusting the amplitude scroll bar will alter the driving
amplitude of the probe's vibration. Adjusting the phase scroll bar alters the phase
degree. For optimal scanning, the amplitude should not exceed 2.5V or the resonance
will become saturated (see section 5.4).
2. Lower, Selected, and Upper Frequency: The lower, selected, and upper frequencies cor-
respond to green, blue, and red vertical bars in the oscilloscope windows, respectively.
V 1.1 / LS-AFM Users Guide
Section 3-3