Scanning Distortion with Bio-Rad 1024

[Michael Hendrickson]

Hello,

We recently replaced the power supply (all five subunits) for our
Bio-Rad 1024 control tower.  After starting the system, there was an
obvious distortion along the X-dimension in all images.  It appears
that the X galvo is zoomed by a factor of ~3.6, resulting in
magnification along only the X-dimension.  The characteristic scanning
sound produced with a zoom factor of 1 (no zoom) is not present,
suggesting that indeed the galvo is set to a zoom of ~3.6.  An image
of 15-micron green beads collected with the system can be seen here:
http://www.keck.bioimaging.wisc.edu/15umbeads.jpg.  All other aspects
of the system work fine, including the zoom function, which allows
zooming but maintains the distortion.  The software calibration
settings do not appear to have changed.

Any insights into the cause of the problem (and how to fix it) would
be greatly appreciated.

Thanks,

Michael Hendrickson
Assistant Manager
W.M. Keck Laboratory for Biological Imaging
University of Wisconsin-Madison
www.keck.bioimaging.wisc.edu

[Mark Cannell]

Most scanning systems have pots that are used to set the scan amplitude.
Simply swapping connectors to x-y motors may reveal a defective scan
motor but you have to watch out if the loop gain of the servo is
critical as the swapped motor may break into oscillation. I'd guess you
need a service book to find the connections and signals to 'tune up' the
motor response. If the Biorad 1024 scanner uses the commercial scan
boards (e.g General Scanning) some tech. info may be available on the web.

Good luck.

Mark

Michael Hendrickson wrote:

> Hello,
>
> We recently replaced the power supply (all five subunits) for our
> Bio-Rad 1024 control tower.  After starting the system, there was an
> obvious distortion along the X-dimension in all images.  It appears
> that the X galvo is zoomed by a factor of ~3.6, resulting in
> magnification along only the X-dimension.  The characteristic scanning
> sound produced with a zoom factor of 1 (no zoom) is not present,
> suggesting that indeed the galvo is set to a zoom of ~3.6.  An image
> of 15-micron green beads collected with the system can be seen here:
> http://www.keck.bioimaging.wisc.edu/15umbeads.jpg.  All other aspects
> of the system work fine, including the zoom function, which allows
> zooming but maintains the distortion.  The software calibration
> settings do not appear to have changed.
>
> Any insights into the cause of the problem (and how to fix it) would
> be greatly appreciated.
>
> Thanks,
>
> Michael Hendrickson
> Assistant Manager
> W.M. Keck Laboratory for Biological Imaging
> University of Wisconsin-Madison
> www.keck.bioimaging.wisc.edu
>  

[Stephen Cody-2]

Dear Michael,

 

Warning: These instructions are only those for the highly computer and confocal competent.

 

There is a hidden menu to set up the waveforms that control the sweep of the galvos. This was done on site by the Bio-Rad service engineer on installation of every system. They use a grid as a specimen, I think of 50 x 50 um. But i see no reason why you couldn't use a bead of known dimensions. The settings under this hidden menu will effect every aspect of the scan mechanism. So before you alter anything you must write down EVERY setting. So that at least you can get back to your starting point if you make it worse. And to begin with you probably will.

 

To get into this hidden menu, whilst running the LaserSharp software hit "Ctrl L". This worked with DOS and OS2 versions of the software I presume it also is part of the NT platform.

 

It has been many years since I tweaked these parameters so I can't give advice on what will need tweaking. In this menu you can bring up a grid overlay as well, set the dimensions of the overlay, then tweak the scan parameters until your beads match the grid.

 

Things to lookout for:

When scanning at 768 x 512 you may see a corner is partially obscured with a circular mask. This too is controlled under the same menu, and allows you to centre the scan area in the microscope better.

 

Check the performance with a straight edge in both x and then Y orientations on your stage. A grid of known dimensions as a specimen is ideal.

 

Good luck,

 

Stephen H. Cody

2009/2/11 Michael Hendrickson <[hidden email]>

Hello,

We recently replaced the power supply (all five subunits) for our
Bio-Rad 1024 control tower.  After starting the system, there was an
obvious distortion along the X-dimension in all images.  It appears
that the X galvo is zoomed by a factor of ~3.6, resulting in
magnification along only the X-dimension.  The characteristic scanning
sound produced with a zoom factor of 1 (no zoom) is not present,
suggesting that indeed the galvo is set to a zoom of ~3.6.  An image
of 15-micron green beads collected with the system can be seen here:
http://www.keck.bioimaging.wisc.edu/15umbeads.jpg.  All other aspects
of the system work fine, including the zoom function, which allows
zooming but maintains the distortion.  The software calibration
settings do not appear to have changed.

Any insights into the cause of the problem (and how to fix it) would
be greatly appreciated.

Thanks,

Michael Hendrickson
Assistant Manager
W.M. Keck Laboratory for Biological Imaging
University of Wisconsin-Madison
www.keck.bioimaging.wisc.edu

--
Stephen H. Cody
Consulting Microscopist