Re: white light laser

Posted by Steffen Dietzel on
URL: http://confocal-microscopy-list.275.s1.nabble.com/white-light-laser-tp7590046p7590073.html

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Dear Zdenk,

this Raman thing sounds very interesting, but I have not much knowledge
about this field. Can you explain at which wavelength you expect this
signal when exciting with 488 nm?

Best

Steffen

Am 24.10.2019 um 18:17 schrieb Zdenek Svindrych:

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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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>> posting.
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>>>
>>> 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
>>
>
--
------------------------------------------------------------
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