Re: optical filters
Becky Bonner (Becky.Bonner@CCLINK.NET.uokhsc.edu)
Wed, 13 Jul 94 18:27:57 CST
Hi Kris,
I don't know a thing about indol so I can't help you there. I do know
something about filters and what happens to them when they are bad ...
First, there is no time limit that one can set on how long a filter
will last. What happens is that the coatings on the glass
deteriorate. The closer your filters are positioned to the mercury
lamp probably the shorter the life. Some coatings have been fried in
2 weeks some 6 months, others never (15 years). Why? I don't really
know ... vendors, manufacturing, humidity, wavelength, number of hours
of continuous operation, and other mysterious stuff.
How can you tell ... at least my experience ... the field is no
longer anywhere near uniform ... and can't be made any better by lamp
realignments or standing on your head. If you put something that
fairly uniformly glows on the microscope stage (like an H&E Liver or a
piece of gelatin filter) and look, you will see cracks, or dark
nondiscrete holes (dark areas) and the like. These coatings don't
seem to deteriorate evenly and have splotches that get worse and worse
over time. Any lense in the system is susceptable to this problem ...
not just your excitation/emission filters since they ALL have
coatings.
Measurements of beads that excite and emit at the desired wavelengths
will give big cv's and broad histograms.
regards,
becky-bonner@uokhsc.edu
>1. Traditionally we have used a 405bp filter and a 350 lp (after a 550dl) for
>co llection of short and long indo1 wavelengths. It has been suggested to me
>that we use a 3 95+/-5nm for short and a 525bp for long. Any opinions?
>2. How long do filters last? I read in Dr. Shapiro's book that this is a very
>individual thing and each filter must be inspected periodically, but is there
>an outer limit ? We have filters that we are using that are 7-10 years old.
>Is this unreasonable? They don't look hazy, but I just wonder if the coatings
>can degenerate in such a way that would n ot be
>visible to my naked eye. I have not noticed problems, but I wonder if I
would necessarily notice a problem with beads or such.
Thanks in advance.
Kris Weber
PS Thanks to all who offered suggestions on the platelets. I should be able to
t ry a lot
of them within the next month.
CD ROM Vol 2 was produced by staff at the Purdue University Cytometry Laboratories
and distributed free of charge as an educational service to the cytometry community.
If you have any comments please direct them to Dr. J. Paul Robinson, Professor & Director, PUCL,
Purdue University, West Lafayette, IN 47907. Phone:(317) 494-0757; FAX (317) 494-0517; Web http://www.cyto.purdue.edu
EMAIL robinson@flowcyt.cyto.purdue.edu
