http://confocal-microscopy-list.275.s1.nabble.com/Objective-phosphorescence-tp7587588p7587600.html
Great points Zdenek. As you say, it seems unusual in a modern objective. I
glass of the lens for these effects. I suppose if the laser is powerful
enough a focus might not be necessary. Ben also mentioned using a singlet
> *****
> To join, leave or search the confocal microscopy listserv, go to:
>
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy> Post images on
http://www.imgur.com and include the link in your posting.
> *****
>
> Hi Craig,
> I'm not that surprised, I've seen luminiscence (in the 0.1 ms range) from
> glass coverslips in a two-photon setup. You won't see this effect in a
> confocal microscope unless you use strong laser power, high gain, and focus
> somewhere into the glass (but be careful, the coverslip chips off easily if
> you focus your 2P laser to the glass-water interface :-).
>
>
> And it's well known that some lenses are better for fluorescence imaging
> than others. You won't see the luminiscence decay with a widefield
> microscope, the cameras are usually not fast enough. It will just increase
> the background in your images. But, to be honest, I would expect this
> effect
> to be extremely weak for modern lenses...
>
> I would definitely double check the LED, too. Many UV LEDs show lot of
> luminescence. But if Ben is using DMD to control the illumination (not the
> LED itself), this can probably be ruled out, and the DMD itself should be
> pretty fast (10 us ?)...
>
> Best, zdenek
>
> --
> Zdenek Svindrych, Ph.D.
> Research Associate - Imaging Specialist
> Department of Biochemistry and Cell Biology
> Geisel School of Medicine at Dartmouth
>
> ---------- Původní e-mail ----------
> Od: Craig Brideau <
[hidden email]>
> Komu:
[hidden email]
> Datum: 21. 11. 2017 10:17:12
> Předmět: Re: Objective phosphorescence
> "*****
> To join, leave or search the confocal microscopy listserv, go to:
>
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy> Post images on
http://www.imgur.com and include the link in your posting.
> *****
>
> That is quite an unusual finding, Ben. It would be interesting to try a
> fused silica lens to see if that gives the same result or not. Glass can
> exhibit all sorts of emissions at shorter wavelength but I have never seen
> this particular situation. Some LEDs use fluorescence or phosphorescence in
> their emission but you seem to have ruled that out. Fused silica *should*
> be pure enough to avoid issues at that wavelength.
>
> Craig
>
>
> On Nov 20, 2017 8:34 PM, "Benjamin E Smith" <
[hidden email]>
> wrote:
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
>
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy> Post images on
http://www.imgur.com and include the link in your 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-3f03c7bc0c80/1.1/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
>
> --
> 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/>
> "
>