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Good evening,

I have experienced this problem earlier on an older motorized stage. The
reason at that time had been a problem with a joystick. The joystick,
which presented one out of two methods to move the table - the other being
software and RS232 connection -, upon starting the system, was
mechanically not entirely in its (0|0) position. It's position was hence
some (x0|y0) at which neither x0 nor y0 were some small values, but not
really 0. Touching the joystick after complete initialization would then
bring it to the (0|0) position, which the joystick, then, interpreted as
(-x0|-y0) and thus brought the table to a slight but steady movement.

Possibly, this is your problem.

Best wishes,

Johannes


> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hello everyone
> We have an encoded (motorized) stage that drifts around 0.5 um (500nm) per
> hour to mostly but not always one direction. Putting an enclosed box to
> surround the microscope seems did not help. Is this something unavoidable
> for a motorized stage? Is using fiducial marker the only solution if
> experiment requires high accuracy of XY position over long period of time?
> I would appreciate for any thought and advice.
>
> Jianbo Chen
> HIV Drug Resistance Program
> National Cancer Institute-Frederick
> Frederick MD 21702
>
> [log in to unmask]
> 301-846-1841
>
> https://ccrod.cancer.gov/confluence/display/CCRSSSCArchive/Home
>


-- 
P. Johannes Helm

Voice:	(+47) 228 51159 (office)
Fax:	(+47) 228 51499 (office)

-- 
P. Johannes Helm, M.Sc. PhD
Seniorengineer
CMBN
University of Oslo
Institute of Basic Medical Science
Department of Anatomy
Postboks 1105 - Blindern
NO-0317 Oslo

Voice:	+47 228 51159
Fax:	+47 228 51499

WWW:	folk.uio.no/jhelm