FREQUENTLY ASKED QUESTIONS ABOUT ATOMIC FORCE MICROSCOPY (AFM FAQ)
by Peter Eaton
2. Scanner Artifacts - Effects due to the peculiarities of the piezoelectric scanner
Piezo creep occurs because when you apply a set voltage to the piezo(scanner), and then try to maintain it,
in order to move to a certain location,
the piezo tends to continue to move in the same direction for a certain period of time.
Essentially, this means that when you start a new scan, you will get some stretching or compression of features at the
beginnning of the image, and then the image will start to appear more normal over time.
The effect will be particularly pronounced if you move to a new place within your scan range.
See the example below.
In the example above, the image is distorted at the top due to scanner creep. You can read more about the reason for this effect here.
How to avoid it.
The simplest thing to do is just wait until it dissapears, and start scanning again.
Even better, your AFM should allow you to scan one line continuously. Do this, to start,
(pick the line at the top or bottom of the area you want to scan), wait until the image "stabilises"
(i.e. that line is always the same), then start scanning the image properly.
AFMs with linearised scanner do not suffer form this effect.
Note that distorted features all over your image are due to some thing else, maybe sample drift.
Artifacts Index Page
This document was written by, and is maintained by Peter Eaton (firstname.lastname@example.org)
Reproduction or distribution not allowed without my permission.
Please feel free to email me comments / questions / answers.
Document updated on 14th September 2007.