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Thank you for many list members who responded on and off-list.

I can summarize the responses as follows:

1. Some suspect the AOTF and/or the AOBS. Although other lasers do not 
exhibit the problem, these devices are tuned for each line. However, the 
fact that this problem occurs for each of the 4 argon lines, and not for 
561 , 594 and 633, makes me doubt it is the AOTF.

2. Some suggest thermal issues. I checked the fans, and they all work 
(if they did not, that laser would shut down pretty fast). However, I 
cannot rule out a faulty thermal sensor, and am contacting Lasos to see 
how this can be checked.

3. I ran some scans with a fluorescent plastic slide. The results are 
uploaded to http://cl.ly/3K1L1S321925 . This is a LIF file, so you need 
a LIF reader for it. ImageJ will do, but it is easier to see the 
metadata with LAS Lite. Seems hard to find, but this link seems ok:
http://cifweb.unil.ch/index.php?option=com_docman&task=doc_details&gid=26&Itemid=57
This time I included the transmitted light images, which show the same 
effect. I think I can rule out photobleaching. There are various 
combinations of channels, simultaneous, and sequential scanning, using 
488nm or 514nm (argon ion laser) and 561nm (DPSS laser).

I again thank everyone who responded, and will update on the list as I 
obtain more information.

--aryeh
-- 
Aryeh Weiss
Faculty of Engineering
Bar Ilan University
Ramat Gan 52900 Israel

Ph:  972-3-5317638
FAX: 972-3-7384051


>
> -----Original Message-----
> From: Aryeh Weiss <[log in to unmask]>
> Sender: Confocal Microscopy List <[log in to unmask]>
> Date:         Fri, 31 Aug 2012 15:35:44
> To: <[log in to unmask]>
> Reply-To: [log in to unmask]
> Subject: horizontal dark lines appearing
>
>
> We see (apparently) periodic horizontal dark lines with our Leica SP5,
> when using the argon ion laser. Images that show these lines can be seen
> at the following link:
> http://cl.ly/2m2h0R1u1J2w
>
> There were some some posts on the list about this, with the suggestion
> that the laser is dying. However, when last I checked (a few weeks ago),
> that laser was putting out plenty of power (although the 488nm line was
> relatively weak compared to the 514nm line). Also, the lines have some
> periodicity (50Hz?). Faster scan rates increase the line spacing, but it
> does not appear to be linear with scan speed.
> Frame averaging will average it out, so it is not correlated with the
> scanning system. So the lines are annoying, but average signal seems fine.
>
> None of the other lasers do this, and it is independent of detector.
> Therefore, we assume that the problem is upstream of the vis laser
> combiner/AOTF. That leaves the fiber, laser head, and power supply.
>
> We suspect the laser, but it would be more satisfying to understand what
> causes this behavior. Understanding the cause may lead to knowing how to
> fix it without replacing the laser, but even if not, I like to know why
> things work (or dont work) the way they do.
>
> Has anyone has seen something similar?
>
> Thanks in advance
> --aryeh
>