Dear Christophe,

We had a very similar problem with one of our ASI stages (also using MM
software, but I think that's less critical). We also had the suspicion
that there was something wrong with the stability of the stage, then did
lots of measurements, then got the linear encoders cleaned et voila,
everything was fine again.
If you want to argue, the measurement you have to do is the following:
take a position on a slide with a target pattern or a pattern of beads.
Program the stage to move away from the original position and come back
to this position. Repeat in different directions from the origin.
Calculate the root mean square: Square all re-localization differences
to avoid negative values, then square root, then take the mean. At least
30 measurements was what I was told to do. Compare the value with the
specs of the stage.
We could not access the linear encoders for cleaning, because we had a
z-piezo version of the stage, so we had to send it in for cleaning. ASI
was kind enough to provide us with a replacement stage while they did
the cleaning. Excellent service, though it took us a while to convince
our system provider of the problem.

Good luck, jens.

-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]]
On Behalf Of Christophe Leterrier
Sent: Wednesday, February 18, 2009 16:47 PM
To: [log in to unmask]
Subject: XY stability of motorized stage

Dear all,

I'm concerned about the XY stability of a motorized stage. It is a ASI
MS-2000, equipped with XY linear encoders, controlled by Metamorph
Software. Using a 100X objective and a 1.6 magnifying lens, and
aquiring at a fixed position, I can get up to 1 micron drift over half
an our. That is, the amplitude of movement is inside a 1 micron
diameter circle, but the test bead can have a several micron
trajectory inside this circle (up to 5 or 10 microns total movement).
These are the worst cases, usually I have a few pixels drift (that is
around 500 nm). This is

Is that stability acceptable or should I have the stage serviced ?
What can be the cause of instability (I'm already inside a big
incubator box, on an optics air table, with all cables and wires
coming from the ceiling...).

Christophe Leterrier