How to align an AOTF?

[Mark Willett]

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Hi folks,

I need a bit of advice if possible.

I am attempting to configure a spinning disk system (a Ti Eclipse stand with a Yokagawa head).

The lasers are mounted on a separate breadboard with a fibre to the scan head.  I'm having a few problems getting the AOTF to work and this is not my field of expertise.

The setup is:
405 nm laser reflected direct to the collimating lens on the fibre coupling and modulated via voltage using Micromanager.
The 488, 561 and 660 nm lasers are reflected into the same light path which is then directed through the AOTF into the collimating lens. These lasers are all aligned with each other at the point where they enter the AOTF.

The AOTF (Gooch & Housego) is mounted on a post with 2 D.O.F. and has an additional adjustment knob on top which allows it to be rotated vertically in relation to the light path.

We have a power meter on the opposite end of the fibre, and we can't detect any deflection of the laser light when it is aligned with the collimating lens and the AOTF is modulated, so the AOTF appears to be out of alignment.

Can anybody provide any insight into a useful method for aligning the AOTF?

Many thanks for your help!
Mark

Dr Mark Willett
Manager, Imaging and Microscopy Centre

Centre for Biological Sciences
3103 Building 85
University of Southampton
SO17 1BJ
Tel: [phone]
http://www.southampton.ac.uk/microscopy/

[George Peeters-2]

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Hi Mark
We used the same AOTF set-up prior to switching our lasers to directly modulated lasers in 2009.

The AOTF from G&H has two beams exiting the AOTF Out-window; the top one is lined up with the fiber optic the lower beam ~ 15 degrees deflected is tossed.

You need to measure just the top beam with ony the 488 line on (turn off or shutter the other lasers) and compare it to the power in both beams. You should get > 90% into the top beam if the freq. and the power of the RF signal is tuned correctly, and the beam is passing thru the AOTF in the ~ 2mm window.  We remove the FO collimator to improve the access to the top beam and physically adjust the tilt and position of the AOTF to acheive this level of selection.

If you have the G&H model that is programmable via USB you can fine tune the freq. and Power;  if you have the older model with radio buttons then you grossly line it up with the preset channel and open the driver box to access fine tuning of the power and freq. (8 channel model).

 Tools:  fast response Si-wand for the power meter, small screw driver


Good Luck

George
George Peeters, M.D., M.S.
Pres. Solamere Technology Group inc.
1515 Military Way
Salt Lake City, UT.  84103

Cell    801 232-6911





On Apr 29, 2016, at 9:09 AM, Willett M. <[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 folks,
>
> I need a bit of advice if possible.
>
> I am attempting to configure a spinning disk system (a Ti Eclipse stand with a Yokagawa head).
>
> The lasers are mounted on a separate breadboard with a fibre to the scan head.  I'm having a few problems getting the AOTF to work and this is not my field of expertise.
>
> The setup is:
> 405 nm laser reflected direct to the collimating lens on the fibre coupling and modulated via voltage using Micromanager.
> The 488, 561 and 660 nm lasers are reflected into the same light path which is then directed through the AOTF into the collimating lens. These lasers are all aligned with each other at the point where they enter the AOTF.
>
> The AOTF (Gooch & Housego) is mounted on a post with 2 D.O.F. and has an additional adjustment knob on top which allows it to be rotated vertically in relation to the light path.
>
> We have a power meter on the opposite end of the fibre, and we can't detect any deflection of the laser light when it is aligned with the collimating lens and the AOTF is modulated, so the AOTF appears to be out of alignment.
>
> Can anybody provide any insight into a useful method for aligning the AOTF?
>
> Many thanks for your help!
> Mark
>
> Dr Mark Willett
> Manager, Imaging and Microscopy Centre
>
> Centre for Biological Sciences
> 3103 Building 85
> University of Southampton
> SO17 1BJ
> Tel: [phone]
> http://www.southampton.ac.uk/microscopy/