Some notes on aligning the laser through the beam transport.

Update Nov 2021: Most of the alignment is now indeed automated and can be controlled using Claudio's GUI, but camera issues still require manual alignment every now and thenMarch 2022: The auto aligner works best when aligning manually to references, set a tight ROI an let the aligner stabilise there. B4-B6 tend to be quite noisy due to radiation damage and require manual alignment. That means a combination of manual and automated alignment is currently in place.

References can be found here and are hard-coded into the auto-aligner: Laser cameras and alignment references

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• Press 'Stop Alignment' (red button). This will stop any scripts running on other machines.
• Check gain settings by clicking the 'Expert...' button. No gain should be above 0.2000. Higher values tend to overshoot too much and affect pointing.
• Then tick boxes for the references/mirrors to align and click 'Clear References', then 'Grab References', and 'Start Alignment'.

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• For the IR laser in the laser room we use the first two lines (Pulse Picker and Regen Out, Preamp Near and Far). We are NOT using MPA Near and Far at this moment (Feb 2022).
• For the beam transport we use HeNe Near and Far, B0/B1, B2/B3, B5 and B6. B5 and B6 need background subtraction. B4 is B4-B6 are currently too noisy to work reliably and we align it them manually (Feb March 2022).

• The HeNe can be blocked and unblocked using the button under HeNe status. It is recommended to press 'Pause Alignment' (orange button) to avoid issues with the aligner.

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• Go to facethome → Matlab GUIs → Profile Monitor and then the respective camera (HeNeNear etc.).
• One can check the axis orientation by printing the log book:
  
  
  
• Tick the box for 'Show Stats'. A separate smaller window should open which fits an ellipse to the beam.
  If the fit doesn't succeed, it might be necessary to change the exposure.
  If the image is saturated, it might be necessary to set the camera to 16 bit (go to camera Advanced → AD Base)
  
  
  
• Now find the pico motors: Go to Laser → Li20 → Infrastructure. Check MOC-LI20-MC0X for right pico motors.
  
  
  
• Before using the pico motors, check if they are still working by clicking on MAINT → Check Motors
  
  
  If motors are dead, go to ACSW:LI20:NW19 (found on same page as MOCs) and turn on and off again
  
  
  
  
• When motors come back, check the current and request value are the same
• When using arrows on picomotors, need to press enter when changing step size
  
  
• Note that the profile monitors indicate the beam position behind that particular mirror, e.g. behind B0. To change the beam position, one has to move the mirror BEFORE that mirror, e.g. Launch mirror for B0, B0 for B1 and so on.
• Note also that the HeNe signal gets weaker further downstream
• At B4 and further downstream one might have to use a background and long exposure (second(s)). For that either quickly turn off the HeNe (not so ideal because the laser needs to warm up) or someone goes into the laser room and blocks the HeNe.

IR:

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Matching IR to HeNe beam path

Now after aligning the HeNe, we can proceed with using the IR laser and overlapping its beam path with the HeNe.

• Check references on DMNear and Far for both pulsed and CW
• Stop/Pause auto aligner

• Block HeNe in laser room (this is now motorised):
  The
  Click 'Block' button under HeNe status in auto aligner GUI.
  
  Alternatively, the motor can be found at facet home → Laser → LI20 → Infrastructure → Controllers (mid column): XPS MOC-LA20-LS24 → Ch3
  IN is at 10, OUT is at 8. OUT means block is out and laser can pass.

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• Close Iris near the DM to 'Align' -5 mm (now motorised).
• Increase exposure on B0 and B1 to 2 s (or see Laser cameras and alignment references)
• Now someone has to bring on the laser in the tunnel (close laser curtains and turn key)
• Open shutter on Laser → LI20→ Laser and then the shutter next to LSS EPS EPICS from High to Low

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• Look at beam on B0 and B1 and use M4 and M5 in Laser room 2 tab to align to same reference coordinates as before.
  Note that the motions are not independent, so one might have to iterate a few times.
  Henrik mentioned it might be faster to start with B1 as M5 is being bumped more regularly, especially after using the rail setup in the laser room (divergence measurements or axicon characterisations).
  
  
  
• Might have to change polarization to see a good signal on B1 (wave plate). 
  Wave plate can be found on the same motor controller as the HeNe block (Ch2).
  Move by 15 units either way from 50.
  
  
• After alignment, reset wave plate and set iris back to nominal beam size.
• Reset exposure time on B0 and B1 to short exposure
• Clear references on auto aligner, grab new references and start auto alignment again.

• For main beam alignment, align now to references on CompNear/Far and PBNear/Far. Suitable iris setting is -10 mm.