Re: Laser beam sharing via multi-mode fibers

Posted by jcv2@uw.edu on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Laser-beam-sharing-via-multi-mode-fibers-tp7584037p7584038.html

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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:

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