UV lasers

Larry Arnold lwarma at med.unc.edu
Tue Feb 5 17:25:39 EST 2002


I would suggest getting the laser refurbed.  As long as the plasma tube is
not cracked it is easy for them to do.  I would suggest contacting Phil at
Evergreen Laser (www.evergreenlaser.com).  He has done several I-90
rebuilds for me.  When operating an I-90 in UV you have to be careful not
to let the tube overfill which is what the over pressure means.  If it
overfills beyond a certain point it does away with the UV but may still
operate in visible.  Try switching it over to visible and see.  To prevent
overfilling disconnect the fill circuit and move it to the "spare" position
on the main terminal strip on the side of the magnet on the tube (have to
remove the cover to get to it).  If the laser will operate it may burn off
enough to get the UV back.  Call Phil and talk this over with him to
confirm what I say is correct.  If you get it back leave the fill circuit
disconnected.  Ever once in a while you will have to reconnect it for a day
to let it refill.  If operating the I-90 in visible you don't need to keep
the fill circuit disconnected.  Good luck.


At 02:51 PM 2/1/2002, you wrote:

>Hi, everyone:
>I'm running an EPICS Elite with a gated amplifier and 5 PMTs.  We have 3
>lasers, one of which is an old Coherent Innova 90 which we have been using
>for its UV wavelengths.  Unfortunately, it has been running "over pressure"
>for some time, and now gives me an "under voltage" error message.  It now
>will not operate in "light regulation" mode, so I think that it's
>usefullness as a UV source is at an end.  So, what to do now (with a
>limited budget)?
>I've heard that there are air-cooled UV lasers now available.  Do any of
>you have experience using one of these for flow?  Are they adequate for
>doing calcium studies with indo-1 or DNA with Hoechst 33342?  What
>manufacture/model do you recommend?
>Or, are water-cooled lasers still preferred for flow work?  If so, please
>give me your recommendation for getting the plasma tube replaced in our old
>Innova 90.  (Or is there some reason not to try to repair the Innova 90?)
>Thanks in advance for your advice.
>Rick Meister
>* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>*  Richard K. Meister                  Email:  meister.1 at osu.edu  *
>*  The Ohio State University           Voice:  (614) 292-9716     *
>*  Dept. of Veterinary Biosciences     FAX:    (614) 292-6473     *
>*  Cytometry Instrumentation Lab                                  *
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Larry W. Arnold, Ph.D.
Associate Professor
Director, Flow Cytometry Facility
Department of Microbiology and Immunology
Lineberger Comprehensive Cancer Center
CB# 7290
University of North Carolina at Chapel Hill
Chapel Hill, NC 27599
Phone: 919-966-1530
FAX: 919-962-8103

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