Laser beam sharing via multi-mode fibers

[Kyle Michael Douglass]

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Hello everyone,

In my lab we have two microscope setups in two different rooms separated
by a hallway between them. One of our microscopes has a free-space laser
that must remain in place; however, I would like to use this laser with
the microscope located in the other room while maintaining its ability
to be used with its current microscope. Both microscopes accept
free-space beams as inputs for fluorescence microscopy in an
epi-illumination geometry.

I am considering the following solution: introduce a flipper mirror
before the fixed laser to allow me to switch between a path that would
send the beam into its current microscope and another path that would
couple the beam into a long multi-mode fiber. I would then run the fiber
above the ceiling panels between the labs and onto the table of the
other setup, where the output light would be collimated and introduced
like normal into the other microscope. I do not require a single-mode
beam for the second microscope. In fact, I am proposing to use a
multi-mode beam to achieve a better power coupling efficiency into the
fiber and to prevent burning the fiber cladding by allowing for larger
focal spot sizes when coupling. I also am not concerned about the
speckle on the sample since I am averaging over multiple speckle
patterns during the acquisition of a single frame.

My primary concern is the stability of the input and output couplers.
The microscopes are used by people with little optics experience and
this solution must be as easy as possible to switch between the two
paths. Ideally, the only action required would be to flip the mirror up
or down (after the initial alignment, of course).

Here are my questions:
1. Has anyone tried such an approach with satisfactory results and would
be willing to comment?
2. Would vibration of the fiber significantly affect its propagation
direction upon leaving the output coupler?
3. Would a "standard" flipper mirror or magnetic mount have sufficient
return accuracy to avoid having to adjust the input coupler alignment
every time we switched between microscopes?
4. Is there another obvious solution I am missing?

Thanks for the responses!
Kyle

--
Kyle M. Douglass, PhD
Post-doctoral researcher
The Laboratory of Experimental Biophysics
EPFL, Lausanne, Switzerland
http://kmdouglass.github.io
http://leb.epfl.ch

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Dear Kyle,

I believe a good flipper mount would have sufficient return accuracy when
aligned carefully to flip in the plane of the mirror (e.g., 'sideways') but
it is a little bit of a hassle and someone will eventually bump the mirror.

How about using a polarizer to split the beam and in front of that install
a half waveplate to allow you to select the ratio of power between the two
paths? This seems more robust for general use in my opinion.


Best regards,
Josh

On Thu, Jul 30, 2015 at 12:25 AM, Kyle Douglass <[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.
> *****
>
> Hello everyone,
>
> In my lab we have two microscope setups in two different rooms separated
> by a hallway between them. One of our microscopes has a free-space laser
> that must remain in place; however, I would like to use this laser with the
> microscope located in the other room while maintaining its ability to be
> used with its current microscope. Both microscopes accept free-space beams
> as inputs for fluorescence microscopy in an epi-illumination geometry.
>
> I am considering the following solution: introduce a flipper mirror before
> the fixed laser to allow me to switch between a path that would send the
> beam into its current microscope and another path that would couple the
> beam into a long multi-mode fiber. I would then run the fiber above the
> ceiling panels between the labs and onto the table of the other setup,
> where the output light would be collimated and introduced like normal into
> the other microscope. I do not require a single-mode beam for the second
> microscope. In fact, I am proposing to use a multi-mode beam to achieve a
> better power coupling efficiency into the fiber and to prevent burning the
> fiber cladding by allowing for larger focal spot sizes when coupling. I
> also am not concerned about the speckle on the sample since I am averaging
> over multiple speckle patterns during the acquisition of a single frame.
>
> My primary concern is the stability of the input and output couplers. The
> microscopes are used by people with little optics experience and this
> solution must be as easy as possible to switch between the two paths.
> Ideally, the only action required would be to flip the mirror up or down
> (after the initial alignment, of course).
>
> Here are my questions:
> 1. Has anyone tried such an approach with satisfactory results and would
> be willing to comment?
> 2. Would vibration of the fiber significantly affect its propagation
> direction upon leaving the output coupler?
> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> return accuracy to avoid having to adjust the input coupler alignment every
> time we switched between microscopes?
> 4. Is there another obvious solution I am missing?
>
> Thanks for the responses!
> Kyle
>
> --
> Kyle M. Douglass, PhD
> Post-doctoral researcher
> The Laboratory of Experimental Biophysics
> EPFL, Lausanne, Switzerland
> http://kmdouglass.github.io
> http://leb.epfl.ch
>

--
Joshua C. Vaughan
Assistant Professor
Department of Chemistry
Box 351700
University of Washington
Seattle, WA 98195
206-543-4644

[Mark Cannell-2]

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Yes, this could work or for a no moving part solution how about an acousto-optic deflector which could also provide intensity modulation?

HTH

M

On 30/07/2015, at 9:12 am, Joshua Vaughan <[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.
> *****
>
> Dear Kyle,
>
> I believe a good flipper mount would have sufficient return accuracy when
> aligned carefully to flip in the plane of the mirror (e.g., 'sideways') but
> it is a little bit of a hassle and someone will eventually bump the mirror.
>
> How about using a polarizer to split the beam and in front of that install
> a half waveplate to allow you to select the ratio of power between the two
> paths? This seems more robust for general use in my opinion.
>
>
> Best regards,
> Josh
>
> On Thu, Jul 30, 2015 at 12:25 AM, Kyle Douglass <[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.
>> *****
>>
>> Hello everyone,
>>
>> In my lab we have two microscope setups in two different rooms separated
>> by a hallway between them. One of our microscopes has a free-space laser
>> that must remain in place; however, I would like to use this laser with the
>> microscope located in the other room while maintaining its ability to be
>> used with its current microscope. Both microscopes accept free-space beams
>> as inputs for fluorescence microscopy in an epi-illumination geometry.
>>
>> I am considering the following solution: introduce a flipper mirror before
>> the fixed laser to allow me to switch between a path that would send the
>> beam into its current microscope and another path that would couple the
>> beam into a long multi-mode fiber. I would then run the fiber above the
>> ceiling panels between the labs and onto the table of the other setup,
>> where the output light would be collimated and introduced like normal into
>> the other microscope. I do not require a single-mode beam for the second
>> microscope. In fact, I am proposing to use a multi-mode beam to achieve a
>> better power coupling efficiency into the fiber and to prevent burning the
>> fiber cladding by allowing for larger focal spot sizes when coupling. I
>> also am not concerned about the speckle on the sample since I am averaging
>> over multiple speckle patterns during the acquisition of a single frame.
>>
>> My primary concern is the stability of the input and output couplers. The
>> microscopes are used by people with little optics experience and this
>> solution must be as easy as possible to switch between the two paths.
>> Ideally, the only action required would be to flip the mirror up or down
>> (after the initial alignment, of course).
>>
>> Here are my questions:
>> 1. Has anyone tried such an approach with satisfactory results and would
>> be willing to comment?
>> 2. Would vibration of the fiber significantly affect its propagation
>> direction upon leaving the output coupler?
>> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
>> return accuracy to avoid having to adjust the input coupler alignment every
>> time we switched between microscopes?
>> 4. Is there another obvious solution I am missing?
>>
>> Thanks for the responses!
>> Kyle
>>
>> --
>> Kyle M. Douglass, PhD
>> Post-doctoral researcher
>> The Laboratory of Experimental Biophysics
>> EPFL, Lausanne, Switzerland
>> http://kmdouglass.github.io
>> http://leb.epfl.ch
>>
>
>
>
> --
> Joshua C. Vaughan
> Assistant Professor
> Department of Chemistry
> Box 351700
> University of Washington
> Seattle, WA 98195
> 206-543-4644

Mark  B. Cannell Ph.D. FRSNZ
Professor of Cardiac Cell Biology
School of Physiology &  Pharmacology
Medical Sciences Building
University of Bristol
Bristol
BS8 1TD UK

[hidden email]

[Sudipta Maiti]

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*****

A mirror on a good quality translation stage may be more stable. Of
course, a large core (50 microns or bigger) multimode fiber is rather
forgiving and a flip mount may do just fine.
Sudipta
On Thu, 30 Jul 2015 01:12:34 -0700, Joshua Vaughan 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.

> *****
>
> Dear Kyle,
>
> I believe a good flipper mount would have sufficient return accuracy
> when aligned carefully to flip in the plane of the mirror (e.g.,
> 'sideways') but it is a little bit of a hassle and someone will
> eventually bump the mirror.
>
> How about using a polarizer to split the beam and in front of that

install

> a half waveplate to allow you to select the ratio of power between
> the two paths? This seems more robust for general use in my opinion.
>
> Best regards,
> Josh
>
> On Thu, Jul 30, 2015 at 12:25 AM, Kyle Douglass <[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.
> > *****
> >
> > Hello everyone,
> >
> > In my lab we have two microscope setups in two different rooms
separated
> > by a hallway between them. One of our microscopes has a free-space
laser
> > that must remain in place; however, I would like to use this laser
with the
> > microscope located in the other room while maintaining its ability to
be
> > used with its current microscope. Both microscopes accept free-space
beams
> > as inputs for fluorescence microscopy in an epi-illumination geometry.
> >
> > I am considering the following solution: introduce a flipper mirror
before
> > the fixed laser to allow me to switch between a path that would send
the
> > beam into its current microscope and another path that would couple
the
> > beam into a long multi-mode fiber. I would then run the fiber above
the
> > ceiling panels between the labs and onto the table of the other setup,
> > where the output light would be collimated and introduced like normal
into
> > the other microscope. I do not require a single-mode beam for the
second
> > microscope. In fact, I am proposing to use a multi-mode beam to
achieve a
> > better power coupling efficiency into the fiber and to prevent burning
the
> > fiber cladding by allowing for larger focal spot sizes when coupling.
I
> > also am not concerned about the speckle on the sample since I am
averaging
> > over multiple speckle patterns during the acquisition of a single
frame.
> >
> > My primary concern is the stability of the input and output couplers.
The
> > microscopes are used by people with little optics experience and this
> > solution must be as easy as possible to switch between the two paths.
> > Ideally, the only action required would be to flip the mirror up or
down
> > (after the initial alignment, of course).
> >
> > Here are my questions:
> > 1. Has anyone tried such an approach with satisfactory results and
would
> > be willing to comment?
> > 2. Would vibration of the fiber significantly affect its propagation
> > direction upon leaving the output coupler?
> > 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> > return accuracy to avoid having to adjust the input coupler alignment
every

> > time we switched between microscopes?
> > 4. Is there another obvious solution I am missing?
> >
> > Thanks for the responses!
> > Kyle
> >
> > --
> > Kyle M. Douglass, PhD
> > Post-doctoral researcher
> > The Laboratory of Experimental Biophysics
> > EPFL, Lausanne, Switzerland
> > http://kmdouglass.github.io
> > http://leb.epfl.ch
> >
>
> --
> Joshua C. Vaughan
> Assistant Professor
> Department of Chemistry
> Box 351700
> University of Washington
> Seattle, WA 98195
> 206-543-4644

Prof. Sudipta Maiti
Dept. of Chemical Sciences
Tata Institute of Fundamental Research
Homi Bhabha Road, Colaba
Mumbai 400005, India
Ph. [phone]
Alternate e-mail: [hidden email]
webpage: biophotonics.co.in

[George McNamara]

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*****

Hi Kyle,

It would be a lot simple to just split the power between the two with a
50/50% beamsplitter.

One of the replies mentioned using a polarizing beamsplitter - that
assumes the laser output is not polarized at the location of the splitter.

Robert H. Chow, USC, has two or more microscopes driven from a single
Argon ion laser.

This paper (or same group in other papers) may have useful advice:

Optics clustered to output unique solutions: a multi-*laser* facility
for combined single molecule and ensemble microscopy.
<http://www.ncbi.nlm.nih.gov/pubmed/21974592>

Clarke DT, Botchway SW, Coles BC, Needham SR, Roberts SK, Rolfe DJ,
Tynan CJ, Ward AD, Webb SE, Yadav R, Zanetti-Domingues L,
Martin-Fernandez ML.

Rev Sci Instrum. 2011 Sep;82(9):093705. doi: 10.1063/1.3635536.

PMID:
    21974592


Optics clustered to output unique solutions (OCTOPUS) is a microscopy
platform that combines single molecule and ensemble imaging
methodologies. A novel aspect of OCTOPUS is its laser excitation system,
which consists of a central core of interlocked continuous wave and
pulsed laser sources, launched into optical fibres and linked via laser
combiners. Fibres are plugged into wall-mounted patch panels that reach
microscopy end-stations in adjacent rooms. This allows multiple
tailor-made combinations of laser colours and time characteristics to be
shared by different end-stations minimising the need for laser
duplications. This setup brings significant benefits in terms of cost
effectiveness, ease of operation, and user safety. The modular nature of
OCTOPUS also facilitates the addition of new techniques as required,
allowing the use of existing lasers in new microscopes while retaining
the ability to run the established parts of the facility. To date,
techniques interlinked are multi-photon/multicolour confocal
fluorescence lifetime imaging for several modalities of fluorescence
resonance energy transfer (FRET) and time-resolved anisotropy, total
internal reflection fluorescence, single molecule imaging of single pair
FRET, single molecule fluorescence polarisation, particle tracking, and
optical tweezers. Here, we use a well-studied system, the epidermal
growth factor receptor network, to illustrate how OCTOPUS can aid in the
investigation of complex biological phenomena.
PMID:
21974592


If you cannot find the paper easily online, the corresponding author's
contact information is available at

http://scitation.aip.org/content/aip/journal/rsi/82/9/10.1063/1.3635536

enjoy,

George


On 7/30/2015 2:25 AM, Kyle Douglass 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.
> *****
>
> Hello everyone,
>
> In my lab we have two microscope setups in two different rooms
> separated by a hallway between them. One of our microscopes has a
> free-space laser that must remain in place; however, I would like to
> use this laser with the microscope located in the other room while
> maintaining its ability to be used with its current microscope. Both
> microscopes accept free-space beams as inputs for fluorescence
> microscopy in an epi-illumination geometry.
>
> I am considering the following solution: introduce a flipper mirror
> before the fixed laser to allow me to switch between a path that would
> send the beam into its current microscope and another path that would
> couple the beam into a long multi-mode fiber. I would then run the
> fiber above the ceiling panels between the labs and onto the table of
> the other setup, where the output light would be collimated and
> introduced like normal into the other microscope. I do not require a
> single-mode beam for the second microscope. In fact, I am proposing to
> use a multi-mode beam to achieve a better power coupling efficiency
> into the fiber and to prevent burning the fiber cladding by allowing
> for larger focal spot sizes when coupling. I also am not concerned
> about the speckle on the sample since I am averaging over multiple
> speckle patterns during the acquisition of a single frame.
>
> My primary concern is the stability of the input and output couplers.
> The microscopes are used by people with little optics experience and
> this solution must be as easy as possible to switch between the two
> paths. Ideally, the only action required would be to flip the mirror
> up or down (after the initial alignment, of course).
>
> Here are my questions:
> 1. Has anyone tried such an approach with satisfactory results and
> would be willing to comment?
> 2. Would vibration of the fiber significantly affect its propagation
> direction upon leaving the output coupler?
> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> return accuracy to avoid having to adjust the input coupler alignment
> every time we switched between microscopes?
> 4. Is there another obvious solution I am missing?
>
> Thanks for the responses!
> Kyle
>

--



George McNamara, Ph.D.
Single Cells Analyst
L.J.N. Cooper Lab
University of Texas M.D. Anderson Cancer Center
Houston, TX 77054
Tattletales http://works.bepress.com/gmcnamara/42

[Michael Giacomelli]

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I agree with George that a beam splitter is a better solution (power
permitting).  I have done this with a single mode fiber and had to
adjust the coupling every week or so due to drift.  With multimode you
will be much less sensitive to this (in proportion to the core size),
but larger cores may result in you losing power anyway due to the
larger output core diameter.  If you do go with the flip mirror, I'd
recommend having the deflected beam go into the microscope rather than
the fiber.

As for your second question, vibration can have some small effect on
light propagating through fibers with more than one mode as any
bending of the fiber will alter the distribution of power between
modes.  Probably though if you are routing this fiber through a
ceiling you'll end up randomizing the mode distribution fairly well
anyway so it shouldn't matter too much.

Mike

On Thu, Jul 30, 2015 at 3:25 AM, Kyle Douglass <[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.
> *****
>
> Hello everyone,
>
> In my lab we have two microscope setups in two different rooms separated by
> a hallway between them. One of our microscopes has a free-space laser that
> must remain in place; however, I would like to use this laser with the
> microscope located in the other room while maintaining its ability to be
> used with its current microscope. Both microscopes accept free-space beams
> as inputs for fluorescence microscopy in an epi-illumination geometry.
>
> I am considering the following solution: introduce a flipper mirror before
> the fixed laser to allow me to switch between a path that would send the
> beam into its current microscope and another path that would couple the beam
> into a long multi-mode fiber. I would then run the fiber above the ceiling
> panels between the labs and onto the table of the other setup, where the
> output light would be collimated and introduced like normal into the other
> microscope. I do not require a single-mode beam for the second microscope.
> In fact, I am proposing to use a multi-mode beam to achieve a better power
> coupling efficiency into the fiber and to prevent burning the fiber cladding
> by allowing for larger focal spot sizes when coupling. I also am not
> concerned about the speckle on the sample since I am averaging over multiple
> speckle patterns during the acquisition of a single frame.
>
> My primary concern is the stability of the input and output couplers. The
> microscopes are used by people with little optics experience and this
> solution must be as easy as possible to switch between the two paths.
> Ideally, the only action required would be to flip the mirror up or down
> (after the initial alignment, of course).
>
> Here are my questions:
> 1. Has anyone tried such an approach with satisfactory results and would be
> willing to comment?
> 2. Would vibration of the fiber significantly affect its propagation
> direction upon leaving the output coupler?
> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> return accuracy to avoid having to adjust the input coupler alignment every
> time we switched between microscopes?
> 4. Is there another obvious solution I am missing?
>
> Thanks for the responses!
> Kyle
>
> --
> Kyle M. Douglass, PhD
> Post-doctoral researcher
> The Laboratory of Experimental Biophysics
> EPFL, Lausanne, Switzerland
> http://kmdouglass.github.io
> http://leb.epfl.ch

[Neil Kad]

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*****

Alternatively a motorised flip mirror would prevent users from touching anything useful:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3962

http://www.newport.com/Motorized-Flipper-Optical-Mounts/955083/1033/info.aspx

I've used the Thorlabs one - it has a remote control (useful), and although I don't have a s sensitive an application for it, I do find it to be very good.

Neil

> Date: Thu, 30 Jul 2015 17:08:12 +0630
> From: [hidden email]
> Subject: Re: Laser beam sharing via multi-mode fibers
> To: [hidden email]
>
> *****
> 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.
> *****
>
> A mirror on a good quality translation stage may be more stable. Of
> course, a large core (50 microns or bigger) multimode fiber is rather
> forgiving and a flip mount may do just fine.
> Sudipta
> On Thu, 30 Jul 2015 01:12:34 -0700, Joshua Vaughan 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.
> > *****
> >
> > Dear Kyle,
> >
> > I believe a good flipper mount would have sufficient return accuracy
> > when aligned carefully to flip in the plane of the mirror (e.g.,
> > 'sideways') but it is a little bit of a hassle and someone will
> > eventually bump the mirror.
> >
> > How about using a polarizer to split the beam and in front of that
> install
> > a half waveplate to allow you to select the ratio of power between
> > the two paths? This seems more robust for general use in my opinion.
> >
> > Best regards,
> > Josh
> >
> > On Thu, Jul 30, 2015 at 12:25 AM, Kyle Douglass <[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.
> > > *****
> > >
> > > Hello everyone,
> > >
> > > In my lab we have two microscope setups in two different rooms
> separated
> > > by a hallway between them. One of our microscopes has a free-space
> laser
> > > that must remain in place; however, I would like to use this laser
> with the
> > > microscope located in the other room while maintaining its ability to
> be
> > > used with its current microscope. Both microscopes accept free-space
> beams
> > > as inputs for fluorescence microscopy in an epi-illumination geometry.
> > >
> > > I am considering the following solution: introduce a flipper mirror
> before
> > > the fixed laser to allow me to switch between a path that would send
> the
> > > beam into its current microscope and another path that would couple
> the
> > > beam into a long multi-mode fiber. I would then run the fiber above
> the
> > > ceiling panels between the labs and onto the table of the other setup,
> > > where the output light would be collimated and introduced like normal
> into
> > > the other microscope. I do not require a single-mode beam for the
> second
> > > microscope. In fact, I am proposing to use a multi-mode beam to
> achieve a
> > > better power coupling efficiency into the fiber and to prevent burning
> the
> > > fiber cladding by allowing for larger focal spot sizes when coupling.
> I
> > > also am not concerned about the speckle on the sample since I am
> averaging
> > > over multiple speckle patterns during the acquisition of a single
> frame.
> > >
> > > My primary concern is the stability of the input and output couplers.
> The
> > > microscopes are used by people with little optics experience and this
> > > solution must be as easy as possible to switch between the two paths.
> > > Ideally, the only action required would be to flip the mirror up or
> down
> > > (after the initial alignment, of course).
> > >
> > > Here are my questions:
> > > 1. Has anyone tried such an approach with satisfactory results and
> would
> > > be willing to comment?
> > > 2. Would vibration of the fiber significantly affect its propagation
> > > direction upon leaving the output coupler?
> > > 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> > > return accuracy to avoid having to adjust the input coupler alignment
> every
> > > time we switched between microscopes?
> > > 4. Is there another obvious solution I am missing?
> > >
> > > Thanks for the responses!
> > > Kyle
> > >
> > > --
> > > Kyle M. Douglass, PhD
> > > Post-doctoral researcher
> > > The Laboratory of Experimental Biophysics
> > > EPFL, Lausanne, Switzerland
> > > http://kmdouglass.github.io
> > > http://leb.epfl.ch
> > >
> >
> > --
> > Joshua C. Vaughan
> > Assistant Professor
> > Department of Chemistry
> > Box 351700
> > University of Washington
> > Seattle, WA 98195
> > 206-543-4644
>
>
> Prof. Sudipta Maiti
> Dept. of Chemical Sciences
> Tata Institute of Fundamental Research
> Homi Bhabha Road, Colaba
> Mumbai 400005, India
> Ph. [phone]
> Alternate e-mail: [hidden email]
> webpage: biophotonics.co.in

     

[Joao Lagarto]

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*****

Hi Kyle,
I don't know if this is a problem for you but in case you have a pulsed
laser, the fibre will also cause temporal dispersion of the pulses. This
may be a problem for time-critical applications such as FLIM.
João

Às 08:25 de 30/07/2015, Kyle Douglass escreveu:

> *****
> 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.
> *****
>
> Hello everyone,
>
> In my lab we have two microscope setups in two different rooms
> separated by a hallway between them. One of our microscopes has a
> free-space laser that must remain in place; however, I would like to
> use this laser with the microscope located in the other room while
> maintaining its ability to be used with its current microscope. Both
> microscopes accept free-space beams as inputs for fluorescence
> microscopy in an epi-illumination geometry.
>
> I am considering the following solution: introduce a flipper mirror
> before the fixed laser to allow me to switch between a path that would
> send the beam into its current microscope and another path that would
> couple the beam into a long multi-mode fiber. I would then run the
> fiber above the ceiling panels between the labs and onto the table of
> the other setup, where the output light would be collimated and
> introduced like normal into the other microscope. I do not require a
> single-mode beam for the second microscope. In fact, I am proposing to
> use a multi-mode beam to achieve a better power coupling efficiency
> into the fiber and to prevent burning the fiber cladding by allowing
> for larger focal spot sizes when coupling. I also am not concerned
> about the speckle on the sample since I am averaging over multiple
> speckle patterns during the acquisition of a single frame.
>
> My primary concern is the stability of the input and output couplers.
> The microscopes are used by people with little optics experience and
> this solution must be as easy as possible to switch between the two
> paths. Ideally, the only action required would be to flip the mirror
> up or down (after the initial alignment, of course).
>
> Here are my questions:
> 1. Has anyone tried such an approach with satisfactory results and
> would be willing to comment?
> 2. Would vibration of the fiber significantly affect its propagation
> direction upon leaving the output coupler?
> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
> return accuracy to avoid having to adjust the input coupler alignment
> every time we switched between microscopes?
> 4. Is there another obvious solution I am missing?
>
> Thanks for the responses!
> Kyle
>

[Craig Brideau]

*****
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.
*****

Depending on how straight the run between the rooms is, you might be able
to run a beam tube across the hallway in the ceiling and do it free space
with a periscope. This would save you the headaches of fiber coupling and
reduce any long-term stability issues. I'm guessing you are not up for that
level of 'infrastructure modification' though, so the multimode fiber may
be the way to go. Try to match the design wavelength of your optics as best
as you can to the wavelength of your laser. Assuming you have a
monochromatic source, you can get away with simpler, cheaper optics by
using single-wavelength components. If your laser is a common wavelength
these should be easy to get.

Craig

On Thu, Jul 30, 2015 at 9:59 AM, João Lagarto <[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.
> *****
>
> Hi Kyle,
> I don't know if this is a problem for you but in case you have a pulsed
> laser, the fibre will also cause temporal dispersion of the pulses. This
> may be a problem for time-critical applications such as FLIM.
> João
>
>
> Às 08:25 de 30/07/2015, Kyle Douglass escreveu:
>
>> *****
>> 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.
>> *****
>>
>> Hello everyone,
>>
>> In my lab we have two microscope setups in two different rooms separated
>> by a hallway between them. One of our microscopes has a free-space laser
>> that must remain in place; however, I would like to use this laser with the
>> microscope located in the other room while maintaining its ability to be
>> used with its current microscope. Both microscopes accept free-space beams
>> as inputs for fluorescence microscopy in an epi-illumination geometry.
>>
>> I am considering the following solution: introduce a flipper mirror
>> before the fixed laser to allow me to switch between a path that would send
>> the beam into its current microscope and another path that would couple the
>> beam into a long multi-mode fiber. I would then run the fiber above the
>> ceiling panels between the labs and onto the table of the other setup,
>> where the output light would be collimated and introduced like normal into
>> the other microscope. I do not require a single-mode beam for the second
>> microscope. In fact, I am proposing to use a multi-mode beam to achieve a
>> better power coupling efficiency into the fiber and to prevent burning the
>> fiber cladding by allowing for larger focal spot sizes when coupling. I
>> also am not concerned about the speckle on the sample since I am averaging
>> over multiple speckle patterns during the acquisition of a single frame.
>>
>> My primary concern is the stability of the input and output couplers. The
>> microscopes are used by people with little optics experience and this
>> solution must be as easy as possible to switch between the two paths.
>> Ideally, the only action required would be to flip the mirror up or down
>> (after the initial alignment, of course).
>>
>> Here are my questions:
>> 1. Has anyone tried such an approach with satisfactory results and would
>> be willing to comment?
>> 2. Would vibration of the fiber significantly affect its propagation
>> direction upon leaving the output coupler?
>> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
>> return accuracy to avoid having to adjust the input coupler alignment every
>> time we switched between microscopes?
>> 4. Is there another obvious solution I am missing?
>>
>> Thanks for the responses!
>> Kyle
>>
>>

[Kyle Michael Douglass]

*****
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.
*****

Thanks for the feedback, everyone. I appreciate the help quite a lot.

One thing that is still not clear to me, though, is whether and how the
direction of the laser beam may be affected at the output coupler due to
fiber vibrations. As mentioned by a few others, the speckled intensity
profile at the fiber's output face is going to be randomly modulated as
the fiber vibrates. From my college days, I seem to recall that spatial
mode fluctuations are linked to pointing stability
(http://www.rp-photonics.com/beam_pointing_fluctuations.html) in laser
cavities. Could vibrations of the fiber result in something similar,
whereby the laser leaving the fiber points in random directions with
time? Or would this effect likely be too small to matter for aligning
the beam at the second microscope?

I have an idea that this will not be a serious issue, but I am wondering
if anyone can comment before I invest the time in doing this.

Thanks again everyone!
Kyle

On 07/30/2015 06:18 PM, Craig Brideau 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.
> *****
>
> Depending on how straight the run between the rooms is, you might be able
> to run a beam tube across the hallway in the ceiling and do it free space
> with a periscope. This would save you the headaches of fiber coupling and
> reduce any long-term stability issues. I'm guessing you are not up for that
> level of 'infrastructure modification' though, so the multimode fiber may
> be the way to go. Try to match the design wavelength of your optics as best
> as you can to the wavelength of your laser. Assuming you have a
> monochromatic source, you can get away with simpler, cheaper optics by
> using single-wavelength components. If your laser is a common wavelength
> these should be easy to get.
>
> Craig
>
> On Thu, Jul 30, 2015 at 9:59 AM, João Lagarto <[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.
>> *****
>>
>> Hi Kyle,
>> I don't know if this is a problem for you but in case you have a pulsed
>> laser, the fibre will also cause temporal dispersion of the pulses. This
>> may be a problem for time-critical applications such as FLIM.
>> João
>>
>>
>> Às 08:25 de 30/07/2015, Kyle Douglass escreveu:
>>
>>> *****
>>> 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.
>>> *****
>>>
>>> Hello everyone,
>>>
>>> In my lab we have two microscope setups in two different rooms separated
>>> by a hallway between them. One of our microscopes has a free-space laser
>>> that must remain in place; however, I would like to use this laser with the
>>> microscope located in the other room while maintaining its ability to be
>>> used with its current microscope. Both microscopes accept free-space beams
>>> as inputs for fluorescence microscopy in an epi-illumination geometry.
>>>
>>> I am considering the following solution: introduce a flipper mirror
>>> before the fixed laser to allow me to switch between a path that would send
>>> the beam into its current microscope and another path that would couple the
>>> beam into a long multi-mode fiber. I would then run the fiber above the
>>> ceiling panels between the labs and onto the table of the other setup,
>>> where the output light would be collimated and introduced like normal into
>>> the other microscope. I do not require a single-mode beam for the second
>>> microscope. In fact, I am proposing to use a multi-mode beam to achieve a
>>> better power coupling efficiency into the fiber and to prevent burning the
>>> fiber cladding by allowing for larger focal spot sizes when coupling. I
>>> also am not concerned about the speckle on the sample since I am averaging
>>> over multiple speckle patterns during the acquisition of a single frame.
>>>
>>> My primary concern is the stability of the input and output couplers. The
>>> microscopes are used by people with little optics experience and this
>>> solution must be as easy as possible to switch between the two paths.
>>> Ideally, the only action required would be to flip the mirror up or down
>>> (after the initial alignment, of course).
>>>
>>> Here are my questions:
>>> 1. Has anyone tried such an approach with satisfactory results and would
>>> be willing to comment?
>>> 2. Would vibration of the fiber significantly affect its propagation
>>> direction upon leaving the output coupler?
>>> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
>>> return accuracy to avoid having to adjust the input coupler alignment every
>>> time we switched between microscopes?
>>> 4. Is there another obvious solution I am missing?
>>>
>>> Thanks for the responses!
>>> Kyle
>>>
>>>

--
Kyle M. Douglass, PhD
Post-doctoral researcher
The Laboratory of Experimental Biophysics
EPFL, Lausanne, Switzerland
http://kmdouglass.github.io
http://leb.epfl.ch

[Zdenek Svindrych-2]

*****
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 Kyle,
if you plan to use the fiber output for microscope illumination, you either
need a uniform far-field angular distribution (for Kohler illumination) or a
uniform intensity at the fiber end facet (for critical illumination). I have
tried many tricks to get uniform output from a multimode fiber (e.g. weak
rotating diffusers, shaking coupling lens, shaking the fiber), but it never
worked perfectly (at least in the critical illumination mode, 50 um step
index fiber).

However, there are commercial fiber shakers, e.g. Borealis (Spectral Applied
Research, later bought by Andor, now part of Oxford Instruments) that works
really great, as you can appreciate in Vutara superresolution microscopes
and the new Andor spinning disc systems.
There are no pointing stability issues with multimode fibers, the output
beam (or speckle pattern) is always within the NA of the fiber, though the
pattern changes randomly with time. Just try to focus your laser into a
piece of mm fiber, it's a few USD investment. Or just shine your laser into
a liquid light guide that you find laying around, that might give you an
idea how seriously compromised the uniformity might be...
Good luck!

zdenek



---------- Původní zpráva ----------
Od: Kyle Douglass <[hidden email]>
Komu: [hidden email]
Datum: 31. 7. 2015 2:43:22
Předmět: Re: Laser beam sharing via multi-mode fibers

"*****
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.
*****

Thanks for the feedback, everyone. I appreciate the help quite a lot.

One thing that is still not clear to me, though, is whether and how the
direction of the laser beam may be affected at the output coupler due to
fiber vibrations. As mentioned by a few others, the speckled intensity
profile at the fiber's output face is going to be randomly modulated as
the fiber vibrates. From my college days, I seem to recall that spatial
mode fluctuations are linked to pointing stability
(http://www.rp-photonics.com/beam_pointing_fluctuations.html) in laser
cavities. Could vibrations of the fiber result in something similar,
whereby the laser leaving the fiber points in random directions with
time? Or would this effect likely be too small to matter for aligning
the beam at the second microscope?

I have an idea that this will not be a serious issue, but I am wondering
if anyone can comment before I invest the time in doing this.

Thanks again everyone!
Kyle

On 07/30/2015 06:18 PM, Craig Brideau 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.
> *****
>
> Depending on how straight the run between the rooms is, you might be able
> to run a beam tube across the hallway in the ceiling and do it free space
> with a periscope. This would save you the headaches of fiber coupling and
> reduce any long-term stability issues. I'm guessing you are not up for

that
> level of 'infrastructure modification' though, so the multimode fiber may
> be the way to go. Try to match the design wavelength of your optics as
best

> as you can to the wavelength of your laser. Assuming you have a
> monochromatic source, you can get away with simpler, cheaper optics by
> using single-wavelength components. If your laser is a common wavelength
> these should be easy to get.
>
> Craig
>
> On Thu, Jul 30, 2015 at 9:59 AM, João Lagarto <[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.
>> *****
>>
>> Hi Kyle,
>> I don't know if this is a problem for you but in case you have a pulsed
>> laser, the fibre will also cause temporal dispersion of the pulses. This
>> may be a problem for time-critical applications such as FLIM.
>> João
>>
>>
>> Às 08:25 de 30/07/2015, Kyle Douglass escreveu:
>>
>>> *****
>>> 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.
>>> *****
>>>
>>> Hello everyone,
>>>
>>> In my lab we have two microscope setups in two different rooms separated
>>> by a hallway between them. One of our microscopes has a free-space laser
>>> that must remain in place; however, I would like to use this laser with
the
>>> microscope located in the other room while maintaining its ability to be
>>> used with its current microscope. Both microscopes accept free-space
beams
>>> as inputs for fluorescence microscopy in an epi-illumination geometry.
>>>
>>> I am considering the following solution: introduce a flipper mirror
>>> before the fixed laser to allow me to switch between a path that would
send
>>> the beam into its current microscope and another path that would couple
the
>>> beam into a long multi-mode fiber. I would then run the fiber above the
>>> ceiling panels between the labs and onto the table of the other setup,
>>> where the output light would be collimated and introduced like normal
into
>>> the other microscope. I do not require a single-mode beam for the second
>>> microscope. In fact, I am proposing to use a multi-mode beam to achieve
a
>>> better power coupling efficiency into the fiber and to prevent burning
the
>>> fiber cladding by allowing for larger focal spot sizes when coupling. I
>>> also am not concerned about the speckle on the sample since I am
averaging
>>> over multiple speckle patterns during the acquisition of a single frame.
>>>
>>> My primary concern is the stability of the input and output couplers.
The

>>> microscopes are used by people with little optics experience and this
>>> solution must be as easy as possible to switch between the two paths.
>>> Ideally, the only action required would be to flip the mirror up or down
>>> (after the initial alignment, of course).
>>>
>>> Here are my questions:
>>> 1. Has anyone tried such an approach with satisfactory results and would
>>> be willing to comment?
>>> 2. Would vibration of the fiber significantly affect its propagation
>>> direction upon leaving the output coupler?
>>> 3. Would a "standard" flipper mirror or magnetic mount have sufficient
>>> return accuracy to avoid having to adjust the input coupler alignment

every
>>> time we switched between microscopes?
>>> 4. Is there another obvious solution I am missing?
>>>
>>> Thanks for the responses!
>>> Kyle
>>>
>>>

--
Kyle M. Douglass, PhD
Post-doctoral researcher
The Laboratory of Experimental Biophysics
EPFL, Lausanne, Switzerland
http://kmdouglass.github.io
http://leb.epfl.ch"