Bio-Rad 1024 laser alignment

[Stephen C. Kempf]

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We've decided to go ahead and get the  laser rebuilt for our BioRad 1024 confocal system. In order to ship the laser for rebuild, I have to remove the fiber optic cable. I've removed the plate on the top of the laser that says "Do Not Open" and can see that the fiber optic cable inserts into a barrel with 4 screws that I assume are used both to hold the cable in place and also for alignment of the cable with the laser beam. So, I assume that the beam will have to be aligned with the laser end of the cable when the cable is reinstalled after the laser is rebuilt.

I am familiar with aligning the beam in the scan head, however, I have never done it at the laser end of the cable. Is this difficult? Do you need any special tools? Any information on this would be most welcome.

Thank you,

Steve

[Craig Brideau]

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I've aligned laser launchers on numerous occasions like you describe.  The
screws are very twitchy in assemblies like these, but with patience you can
align them.  I find the best way is to put a power meter on the other end
of the fiber while I adjust the screws until I have maximum throughput.  It
requires a fair bit of playing around; it helps to figure out which screw
tilts the fiber coupler in what dirrection.  Usually it is a see-saw
configuration where one screw is a pivot and the other two push on opposite
sides of the lever.  This means when you tighten one screw you tend to have
to loosen another to get significant movement.  Once you get close to
maximum you then just very slightly tighten the screws sequentially until
you reach max power.

Craig


On Tue, Mar 6, 2012 at 10:07 AM, Stephen Kempf <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> We've decided to go ahead and get the  laser rebuilt for our BioRad 1024
> confocal system. In order to ship the laser for rebuild, I have to remove
> the fiber optic cable. I've removed the plate on the top of the laser that
> says "Do Not Open" and can see that the fiber optic cable inserts into a
> barrel with 4 screws that I assume are used both to hold the cable in place
> and also for alignment of the cable with the laser beam. So, I assume that
> the beam will have to be aligned with the laser end of the cable when the
> cable is reinstalled after the laser is rebuilt.
>
> I am familiar with aligning the beam in the scan head, however, I have
> never done it at the laser end of the cable. Is this difficult? Do you need
> any special tools? Any information on this would be most welcome.
>
> Thank you,
>
> Steve

[Andrew Ridsdale]

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Hello Steve,

You are mostly right about the function of the screws.  When I did this
there was a fifth on the underside.  That is the locking screw.  It's
probably best to loosen it and not touch the others since the ferrule on
the end of the fiber  should be aligned close to the center of the barrel.

The launcher was essentially a Point-Source Kineflex.

You can also check the orientation of the ferrule in the barrel before
removing since it could be a polarization maintaining fiber.

When the laser comes back you can try to re-insert the ferrule and
tighten up locking screw to see if there is coupling;  but, since the
laser will be re-mounted relative to the launcher there might not be
anything.

Then you need to leave the locking screw partially loosened while
adjusting the alignment screws.  Here you really should have a tool that
should have come with the Bio-Rad.  It was an anodized metal tube
similar in size to the ferrule (about 10x 50 mm) with a ~ .5 mm pinhole
in one end.

Insert the pinhole toward the laser first and adjust the two screws on
that end to maximize light through.  Flip it over to do the other end,  
loosening then gently re-setting the locking screw to insert the tool.  
Iterate flipping a couple of times while tightening the locking screw
slightly more each time. This should bring alignment close enough to get
some coupling into the fiber.  From here you can further optimize.

Without the tool be prepared for some frustration.  I don't know if
there is a good protocol for doing this and it can be quite tedious
because there is really almost no coupling into a single-mode fiber
until the alignment is very close.

Beware also of coupling into the fiber cladding.

On 03/06/2012 12:07 PM, Stephen Kempf wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> We've decided to go ahead and get the  laser rebuilt for our BioRad 1024 confocal system. In order to ship the laser for rebuild, I have to remove the fiber optic cable. I've removed the plate on the top of the laser that says "Do Not Open" and can see that the fiber optic cable inserts into a barrel with 4 screws that I assume are used both to hold the cable in place and also for alignment of the cable with the laser beam. So, I assume that the beam will have to be aligned with the laser end of the cable when the cable is reinstalled after the laser is rebuilt.
>
> I am familiar with aligning the beam in the scan head, however, I have never done it at the laser end of the cable. Is this difficult? Do you need any special tools? Any information on this would be most welcome.
>
> Thank you,
>
> Steve

[David Baddeley]

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This probably only makes sense if you're going to be aligning fibres regularly, but replacing the power meter with a light to frequency converter, (http://www.ti.com/lit/ds/symlink/tsl235.pdf), an integrating sphere (ie a ping pong ball), and a small amplified speaker makes the process somewhat less painful (you can keep your eyes and attention on the launch end of the fibre and you get a very distinctive audio feedback as to whether you're increasing or decreasing the coupled power).

cheers,
David


________________________________
 From: Craig Brideau <[hidden email]>
To: [hidden email]
Sent: Wednesday, 7 March 2012 8:17 AM
Subject: Re: Bio-Rad 1024 laser alignment
 
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I've aligned laser launchers on numerous occasions like you describe.  The
screws are very twitchy in assemblies like these, but with patience you can
align them.  I find the best way is to put a power meter on the other end
of the fiber while I adjust the screws until I have maximum throughput.  It
requires a fair bit of playing around; it helps to figure out which screw
tilts the fiber coupler in what dirrection.  Usually it is a see-saw
configuration where one screw is a pivot and the other two push on opposite
sides of the lever.  This means when you tighten one screw you tend to have
to loosen another to get significant movement.  Once you get close to
maximum you then just very slightly tighten the screws sequentially until
you reach max power.

Craig


On Tue, Mar 6, 2012 at 10:07 AM, Stephen Kempf <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> We've decided to go ahead and get the  laser rebuilt for our BioRad 1024
> confocal system. In order to ship the laser for rebuild, I have to remove
> the fiber optic cable. I've removed the plate on the top of the laser that
> says "Do Not Open" and can see that the fiber optic cable inserts into a
> barrel with 4 screws that I assume are used both to hold the cable in place
> and also for alignment of the cable with the laser beam. So, I assume that
> the beam will have to be aligned with the laser end of the cable when the
> cable is reinstalled after the laser is rebuilt.
>
> I am familiar with aligning the beam in the scan head, however, I have
> never done it at the laser end of the cable. Is this difficult? Do you need
> any special tools? Any information on this would be most welcome.
>
> Thank you,
>
> Steve

[Craig Brideau]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

That's a really neat idea!  In fact, many power meters have an analog
output jack; just wire that to the voltage-to-frequency converter, add a
speaker, and away you go!

Craig


On Tue, Mar 6, 2012 at 5:30 PM, David Baddeley
<[hidden email]>wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> This probably only makes sense if you're going to be aligning fibres
> regularly, but replacing the power meter with a light to frequency
> converter, (http://www.ti.com/lit/ds/symlink/tsl235.pdf), an integrating
> sphere (ie a ping pong ball), and a small amplified speaker makes the
> process somewhat less painful (you can keep your eyes and attention on the
> launch end of the fibre and you get a very distinctive audio feedback as to
> whether you're increasing or decreasing the coupled power).
>
> cheers,
> David
>
>
> ________________________________
>  From: Craig Brideau <[hidden email]>
> To: [hidden email]
> Sent: Wednesday, 7 March 2012 8:17 AM
> Subject: Re: Bio-Rad 1024 laser alignment
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> I've aligned laser launchers on numerous occasions like you describe.  The
> screws are very twitchy in assemblies like these, but with patience you can
> align them.  I find the best way is to put a power meter on the other end
> of the fiber while I adjust the screws until I have maximum throughput.  It
> requires a fair bit of playing around; it helps to figure out which screw
> tilts the fiber coupler in what dirrection.  Usually it is a see-saw
> configuration where one screw is a pivot and the other two push on opposite
> sides of the lever.  This means when you tighten one screw you tend to have
> to loosen another to get significant movement.  Once you get close to
> maximum you then just very slightly tighten the screws sequentially until
> you reach max power.
>
> Craig
>
>
> On Tue, Mar 6, 2012 at 10:07 AM, Stephen Kempf <[hidden email]> wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > *****
> >
> > We've decided to go ahead and get the  laser rebuilt for our BioRad 1024
> > confocal system. In order to ship the laser for rebuild, I have to remove
> > the fiber optic cable. I've removed the plate on the top of the laser
> that
> > says "Do Not Open" and can see that the fiber optic cable inserts into a
> > barrel with 4 screws that I assume are used both to hold the cable in
> place
> > and also for alignment of the cable with the laser beam. So, I assume
> that
> > the beam will have to be aligned with the laser end of the cable when the
> > cable is reinstalled after the laser is rebuilt.
> >
> > I am familiar with aligning the beam in the scan head, however, I have
> > never done it at the laser end of the cable. Is this difficult? Do you
> need
> > any special tools? Any information on this would be most welcome.
> >
> > Thank you,
> >
> > Steve
>

[Stephen C. Kempf]

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Thank you, Aryeh, Nick, Craig, David, and Andrew (if I forgot anyone, I apologize) for the information and your suggestions about laser alignment. I'm sure it will be helpful when the time comes. It's possible I may have more questions at that time. So, I may be in touch again. I really appreciate the willingness of people on this list to provide helpful suggestions when questions are asked.

Steve

______________________________________________________________________________
Stephen C. Kempf E-mail: [hidden email]<mailto:[hidden email]>
Associate Professor Tel:  [phone]
Department of Biological Sciences
331 Funchess Hall Fax: [phone]
Auburn University, AL  36849
Lab Web site - http://gump.auburn.edu/kempflab/
Course web sites:
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   Histology  - http://www.auburn.edu/academic/classes/zy/hist0509/index_histology.html