Re: white light laser

Posted by Zdenek Svindrych-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/white-light-laser-tp7590046p7590067.html

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Let me add - it was kind of mentioned already - that Leica WLL+AOBS does
not have the excitation-suppression capability of filter-based systems.
The're trying to improve it with the time gating, but that only works with
HyDs.
As an example, with LSM780 and their low-angle dichroics (and the meta
detector, 488nm Ar-ion) you can see the Raman scattering of water and you
don't even have to try hard. You can't achieve this with AOBS.
Also, the fluorophore saturation (and other nonlinearities) will manifest
at lower power (at least 10x lower, whatever that means practically, but it
depends on temporal pulse width, which is not specified in Fianium or NKT
datasheets, maybe because it varies with wavelength - ask your Leica rep!).
My $0.02 (and no further commercial interest).
zdenek

On Thu, Oct 24, 2019 at 10:53 AM Steffen Dietzel <[hidden email]>
wrote:

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>
> Dear Konstantin,
>
> apart from things that were already mentioned by others, the fact that
> they are pulsed is an advantage and disadvantage. Gated detection with
> the HyDs is an extremely cool feature to get rid of reflected background
> noise. Plant people also seem to love this since you can gate out the
> very short lifetime chlorophyll fluorescence. On the downside, you can
> excite any fluorochrome only every 12.5 seconds, so you may run into
> saturation faster than with a cw laser. Another downside is that the
> excitation line is not as narrow as with single lasers. In other words,
> it seems that the AOTF is not 100% tight against neighboring lines. In
> spectral detection we advise our users to keep 10 nm between excitation
> and detection. This is a very cautious approach, and if you are careful
> and know what you are doing you can get closer. But as a general rule
> we'd prefer to be on the safe side for the HyDs. Now you could argue
> that the gated detection reflection suppression is a problem that you
> wouldn't have without the WLL, but I don't think so. Some samples
> somehow create a strong reflection near the coverslip that I don't think
> is coming from the WLL, I know this pattern also from single line systems.
>
> Also, the option of exciting with 670 opens up another channel above 630
> excitation that you don't reach with a 488/552/594/633 battery of lasers.
>
> Maybe in some experiments it is helpful to know that there will be zero
> misalignment between the laser lines (except for the 405 and the WLL)
>
> Just my two euro-cents.
>
> Steffen
>
>
>
> Am 21.10.2019 um 15:28 schrieb Konstantín Levitskiy:
> > *****
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> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
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> posting.
> > *****
> >
> > Dear Microscopists,
> >
> > Do you know if any other company, besides Leica, include white light
> laser
> > in their confocals. Or if any other technology can replicate the free
> > selection wavelength laser light? On the other hand, what are
> disadvantages
> > of the WLL?
> >
> > Best regards,
> >
> > Dr. Konstantín Levitskiy
> >
> > Servicio de Microscopía
> >
> > InstitutodeBiomedicinadeSevilla - IBiS
> >
> > Email:  <mailto:[hidden email]> [hidden email]
> >
> > Web:  <http://www.ibis-sevilla.es/> www.ibis-sevilla.es
> >
> >
> >
> --
> ------------------------------------------------------------
> Steffen Dietzel, PD Dr. rer. nat
> Ludwig-Maximilians-Universität München
> Biomedical Center (BMC)
> Head of the Core Facility Bioimaging
>
> Großhaderner Straße 9
> D-82152 Planegg-Martinsried
> Germany
>
> http://www.bioimaging.bmc.med.uni-muenchen.de
>

--
--
Zdenek Svindrych, Ph.D.
Research Associate - Imaging Specialist
Department of Biochemistry and Cell Biology
Geisel School of Medicine at Dartmouth