http://confocal-microscopy-list.275.s1.nabble.com/Objective-phosphorescence-tp7587588p7587609.html
Mt. Pleasant, MI 48859
testing with a singlet I realized it was really the glass. That said, many
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>
> On thing to note about the glue hypothesis is that the singlet lens (i.e.
> no glue) showed the brightest luminescence. Also, the glass in optical
> fibers is a whole different beast, where the glass is actually deposited
> via very high purity gasses:
https://www.youtube.com/watch?v=u1DRrAhQJtM>
> One of my favorite facts about the glass in fibers is that if the ocean was
> as clear as an optical fiber, you could clearly see the bottom. As was
> suggested by Craig, fused silica lenses should be of a similar purity, so
> they should show a similar low level of luminescence to optical fibers. If
> I had one floating around I'd try it, but we normally work in the nIR as
> opposed to UV.
>
> -Ben Smith
>
> On Tue, Nov 21, 2017 at 11:25 PM, Gerhard Holst <
[hidden email]>
> wrote:
>
> > *****
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> > *****
> >
> > Dear all,
> >
> > from my experiences with fiber optics and microscopes, I would expect
> that
> > the additional luminescence might come more from the used glue to fix the
> > lenses within the objectives. I guess for manufacturing reasons, to
> reduce
> > the times for polymerization often UV hardening might be used. As long
> as a
> > light beam just passes the lenses, there is only little issue (we are
> using
> > laser light for widefield illumination of the microscope stage, but we
> > don't have issues with such a background), in case the LED light is able
> to
> > be spread within the objective casing, some luminescence might excited
> > within the glue and part of it will be guided through the optical system
> as
> > well.
> >
> > Could the LED light be better shaped, such that I travels mainly through
> > the lenses?
> >
> > with best regards,
> >
> > Gerhard
> >
> >
> > Dr. Gerhard Holst
> > Head of Science & Research
> > +49 (0) 9441 2005 0
> > +49 (0) 172 711 6049
> >
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> Johann
> > Plöb
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Confocal Microscopy List [mailto:
[hidden email]]
> > Im Auftrag von Martin Wessendorf
> > Gesendet: Mittwoch, 22. November 2017 00:16
> > An:
[hidden email]
> > Betreff: Re: Objective phosphorescence
> >
> > *****
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> posting.
> > *****
> >
> > Interesting. I was using the widefield 'scope in my lab today and saw
> > something that I've seen a thousand times before, but never thought
> > about: Near-UV excitation causes the optics in my sub-stage condenser to
> > fluoresce yellow. However, as others have said, I don't know whether the
> > source is the glue, the glass, or the housing.
> >
> > Martin Wessendorf
> >
> >
> >
> >
> > On 11/20/2017 9:33 PM, Benjamin E Smith wrote:
> > > *****
> > > To join, leave or search the confocal microscopy listserv, go to:
> > >
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> > posting.
> > > *****
> > >
> > > Hey microscopists,
> > > We observed an odd phenomenon today on a microscope and was
> > > wondering if anyone else has ever seen it. We were using a DMD do a
> > > full field flash with 420nm light during the flyback of the scanning
> > > mirror on a 2P imaging rig. We noticed that after the light was
> > > turned off, there was a millisecond long slewing of the signal that
> > > looked a lot like phosphorescence. In the following image, you can
> > > see that the LED is on for the first portion of the scan, then turns
> > > off and the apparent
> > > afterglow:
https://goo.gl/2ENHwL> > >
> > > This afterglow was also apparent with an oscilloscope looking at the
> > > PMT and fast mirror signals:
https://goo.gl/2AMsvB> > >
> > > We then systematically removed components from the optical path,
> > > and cleaned everything, and we were eventually able to determine that
> > > the glass in the objective itself was glowing, where if the objective
> > > was removed and the DMD image was shined onto a piece of lens paper or
> > > metal, the afterglow went away:
> > >
https://goo.gl/arXYF5> > >
https://goo.gl/cVo2Ev> > >
> > > The final nail in the coffin to our suspicions was when we then
> > > mounted a plano-convex N-BK7 lens onto the microscope and the effect
> > > came back, and the thicker the lens, the stronger the effect. Also,
> > > the effect went away when we used 540nm light.
> > >
> > > With a bit of internet searching I also came across this paper that
> > > confirms there is some visible fluorescence in glass due to trace
> > elements:
> > >
http://www.schott.com/d/advanced_optics/87330898-4e56-4d70-965a-3f03c7> > > bc0c80/1.1/schott_tie-36_fluorescence_of_optical_glass_us.pdf
> > >
> > > Even when I saw the slew, and the first thing that came to mind was
> > > phosphorescence, the last thing that came to mind was that the glass
> > > in the objective itself was the offender, so I wanted to post this to
> > > both give other people a heads-up, and also to see if anyone else has
> > > run into this phenomenon.
> > >
> > > Cheers,
> > > Ben Smith
> > >
> >
> > --
> > Martin Wessendorf, Ph.D. office: (612) 626-0145
> > Assoc Prof, Dept Neuroscience lab: (612) 624-2991
> > University of Minnesota Preferred FAX: (612) 624-8118
> > 6-145 Jackson Hall, 321 Church St. SE Dept Fax: (612) 626-5009
> > Minneapolis, MN 55455 e-mail:
[hidden email]
> >
>
>
>
> --
> Benjamin E. Smith, Ph. D.
> Imaging Specialist, Vision Science
> University of California, Berkeley
> 195 Life Sciences Addition
> Berkeley, CA 94720-3200
> Tel (510) 642-9712
> Fax (510) 643-6791
> e-mail:
[hidden email]
>
http://vision.berkeley.edu/?page_id=5635 <
http://vision.berkeley.edu/>
>