Optically-Assisted Tip Approach - AFM Workshop LS-AFM User Manual

4.5 Optically-Assisted Tip Approach

Tip approach with the LS-AFM is achieved using a woodpecker algorithm activated in the
Pre-Scan window. To save time during tip approach, move the probe as close to the surface
as possible before activating the Automatic Tip Approach function. The video microscope
can prove very helpful for manual probe approach. Below are two images of a probe as it
moves toward a standard reference sample surface.
4.5.1 Perform optically assisted tip approach
1. Focus the video microscope on the
sample surface.
2. Carefully lower the Z motor with the
Manual Z Motor Control, or manually
with the motor knob, until the cantilever
is visible in the video microscope image.
Make sure the Jog Size has been set to
a low step size and the Z motor speed
is set to 0.00 mm/sec in order to avoid
crashing the probe into the sample.
3. Slowly jog the probe down until it is only
slightly out of focus.
4. As the probe approaches the surface,
a second laser spot will appear on the
surface if the sample is reflective. Once
the second laser spot merges with the
spot on the cantilever, the tip is flush
with the surface. This effect is useful for
judging the distance from the probe to
the sample.
CAUTION: If the tip touches the surface before the feedback is activated,
the tip may be damaged or even broken.
Section 4-5
Tip Far Away From Suface
Tip Near Surface
V 1.1 / LS-AFM Users Guide