Dear Dr. Robinson,

I'm glad you brought up this issues. I have been working on a NIkon RCM
confocal system for over a year.  It is also equipped with a Coherent
enterprise laser.  I found the same  problem for the
excitation filter.  Actually i have replaced the 488 nm excitation filter
two times during the past year.  The maximum laser output for the visible
light of my system is 1 W.  I have been always wondering if some
companies supply high quality exciters which can hold several walts of
laser power.

   One thought I'm going to try is to put a ND filter infront of
the excitaiton filter.  But I'm not sure whether the ND filter will
degrade if high power laser light keeps shining on it.  I will welcome any
interesting discussions on this issue.

Best!

Weijun Qian

------------------------------------------------------------------------
Weijun Qian
Department of Chemistry, P.O. Box 117200
Gainesville, 32611-7200
Phone: 352-846-0838(O)



On Fri, 29 Oct 1999, J.Paul Robinson wrote:

> Colleagues:
> I 'd like to report on a recent problem that caused us some lost time on our
> confocal microscope (BioRad MRC 1024 UV/Vis system). We have been
> doing a lot of reflection imaging lately and recently encountered a situation
> where the quality of the images suddenly dropped off badly.
>
> It turns out the problem was a burned filter. It was hard to identify because
> it was one of those problems that did not have an obvious solution (well not
> to me anyway).
>
> I took some photos for those interested and they can be seen on
> http://www.cyto.purdue.edu/flowcyt/confocal/cfcl4.htm
>
> The bottom line is yes - filters do degrade and excitation filters can be
> damaged eventually. We have been using the system continuously for 5
> years.  These particular filters are excited by the Coherent Enterprise laser.
> They only have the visible lines going through them. Has anyone else seen
> this problem?
>
> Thanks
>
> Paul Robinson
>
>
> J.Paul Robinson, PhD             PH:(765)4940757
> Professor of Immunopharmacology
> Professor of Biomedical Engineering
> Purdue University          FAX:(765)4940517
> EMAIL:[log in to unmask]
> WEB: http://www.cyto.purdue.edu
>