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Procedure to start up and align the IR laser in the laser room.

Assumption is that the oscillator and Regen are running, and that the auto aligner is being used as much as possible.

The controls for the laser system are found on the laser control panels (FACETHOME→Laser→LI20→PyDM Laser Control Panels). The panels contain buttons to switch back and forth between the laser room, the transport, and the tunnel. The procedure will reference the panel where the buttons are located.

The auto aligner uses the references recorded here Laser cameras and alignment references. If those change, the values have to be changed in the code as wellin the config file found on the control system at $TOOLS/pydm/display/user-facet/config/S20LaserConfig.toml. The file must be updated to change the auto-aligner targets.

If an issue appears during the startup procedure, proceed to Procedures to Fix Common Issues.

A) Preparations - in the laser room

Check status of chillers and refill if necessary:
1. Outside laser room:
  1. Regen: Check for any warning/error lights on chiller.
2. Inside : MPA crystal, Oscillator etclaser room:
  1. Oscillator: On the floor below the oscillator, check for low water light.
  2. Main-amp crystal. On the floor near the main amplifier, check for low water light.
3. Chiller load for SAGAs: https://docs.google.com/document/d/1tVj5wvT-RQI_wx3ykWPv121MkaEuvCQ05LFtRqwuRRc/
Check for any other alarms. Regen and oscillator running.
Check beam out of MPA is blocked with power meter.
1. Check Chilled Water Load.
Oscillator and regen running:
1. To verify the oscillator is running: The modelocking light should be lit and a spectrum visible on the control computer.
2. To verify the regen is running: A pulse train should be visible on the scope above the regen.
Check that the beam path out of the Main-amp is blocked with the power meter.
Check all manual irises after the main amp are open in the laser room.
Make sure the LSS-2 key (in the box) is in the off position in the laser room LSS-2 control panel.
Open a laser room control panel (FACETHOME→Laser→LI20→PyDM Laser Control Panels→Laser Room Control Panel).
Ensure the transport shutter is blocking the laser (Laser Room Control Panel→Transport Shutter).

B) Start up/warm up - in the laser room

Turn on PreAmp (the Pre-amp pump laser by pushing both the Flashlamp and Q-Switch )buttons on the remote.
Turn on both SAGAs (shutters closed): https://docs.google.com/document/d/1tVj5wvT-RQI_wx3ykWPv121MkaEuvCQ05LFtRqwuRRc/by clicking Start on both control computers.
Once the SAGAs finish their warmup procedure, open SAGA shutters by clicking Open on both control computers.

C) PreAmp and MPA alignment

Open S20 Laser Room Multi Profile Monitor (facet home → Matlab GUIs → S20 Laser Tools → S20 Laser Room Multi Profile Monitor).
Start display and check profiles look fine (cameras are running), and laser is visible.
Make sure ROIs are set somewhat tightly → set Zoom ROI in Profile Monitor GUI if needed.
Open auto align GUI (facet home → Matlab GUIs → S20 Laser Tools → S20 the auto-aligner GUI (FACETHOME→Physics Apps...→S20 Laser Tools→S20 Laser Auto Alignment), see Figure 1the panel in Fig. 3 should open.
Press 'Stop Alignment' (red button). This will stop any scripts running on other machines.
Set camera exposure time for all laser room cameras by pressing 'Amp cameras' (see Figure 1, 3. SET EXPOSURE in the Laser Room Control Panel (bottom right).
Click the 'Expert...' button in the auto-aligner. This opens a new window (see Figure 24).
Check the gain settings. No value should be above 0.20005. Higher values tend to overshoot too much and affect pointing.
Check maximum tolerances on the same panel: Global value around 5 pixels, MPA Near/Far in the end ~20 but initially >100
1. The top box is the global tolerance. Set to 50.
2. The bottom box is the tolerance for the steering into the Main-amp. Start with 150 and reduce to 50 after the alignment converges.
3. Note: The auto-aligner won't do anything if it measures an offset larger than the tolerance. It will print a warning in the log.
In the laser control panel, check profiles look fine, cameras are running, and laser is visible on the first seven screens and S20 Launch:Image Added
Verify ROIs match the above image. If the ROI is incorrect, press the ROI button for each camera on the Laser Room Control Panel.
If the laser is clipped or grossly misaligned on S20 Preamp Out, S20 Main Amp Near, or S20 Main Amp Far:
1. Tick boxes in the auto-aligner for first
three
1. two sets of laser cameras:
'
1. Pulse Picker and Regen Out
', 'Preamp Near and Far', 'MPA Near and Far'.
Click 'Clear References', then 'Grab References'. This might take a few seconds.
1. and Preamp Near and Far.
2. Click Grab References. This will take ~30 seconds. A message will be printed in the log saying grabbing is completed.
3. Click Start Alignment. The software will loop through the list of cameras (top to bottom), calculate offsets and then move motors.
4. Once the laser looks good on S20 Preamp Out, S20 Main Amp Near, and S20 Main Amp Far, click Stop Alignment (red button).
Tick boxes for first three sets of laser cameras: Pulse Picker and Regen Out, Preamp Near and Far, and Mainamp Near.
Click Grab References. This will take ~30 seconds. A message will be printed in the log saying grabbing is completed.
Click Start AlignmentClick 'Start Alignment'. The software will loop through the list of cameras (top to bottom), calculate offsets and then move motors.
1. Note: For MPA Mainamp Near and Far the offset is calculated using a 20-shot average. This step takes a bit longer than for the other motors.
Monitor the auto-aligner log to make sure that the offset tolerances were set appropriately and that the auto-aligner does its job.
1. Reduce max offset tolerance in expert panel once alignment is close.
2. 1. The auto-aligner will write a warning to the log with a reason when it skips an alignment step.
  2. To fix auto-aligner errors, see Procedures to Fix Common Issues.
3. Verify the fluorescence profile looks okay on S20Launch (see reference above).
4. Check the energy on the power meter at the output of the Main-amp.
  1. Should be above 600mJ. Any lower than 600mJ, tell the FACET laser contact so they can do a tune-up
  Open SAGA shutters
  1. .
D) DMNear and
Far alignment
DMFar alignment
1. For tunnel work, manually insert the RP attenuator. For full power laser, remove the RP attenuator.
2. If the Check if RP attenuator is at the "inout" position. If not, put , insert ND flippers in the laser room:
  1. Flip the full power laser ND filter
  in
  1. into the common beam path of the DMNear and DMFar cameras
  , and use a foam to block the laser beam path before the deformable mirror
  1. .
  2. Flip the ND filter in front of the wavefront sensor to the in position.
3. Verify the transport shutter is still blocking the laser (Laser Room Control Panel→Transport Shutter).
4. Unblock the laser after the MPA Main-amp so that the Ti:Sap Sapph laser can propagate to through the DMNear and Far DMFar beam path.
5. Open two profile monitors from Matlab GUI, one for DMNear, one for DMFar. The laser beam should appear on both cameras. If not, increase their exposure time to at least 100ms.
6. Select "Show Stats" for both profile monitors.
  1. For DMFar: If the ROI isn't set correctly, the burn spot on the camera may be visible. If this is the case, do the following:
  2. Click the zoom check box and select the half of the image that does not include the burned spot.
  3. Select the "Stats (Zoom)" checkbox so the stats panel only looks at the zoomed in region of the camera.
7. In FACETHOME, follow Laser→LI20→Infrastructure→MOC-LI20-MC06→DM Near. Use Ch1 and Ch2 to adjust the beam pointing to the reference position on DMNear, and use Ch3 and Ch4 to adjust to the reference position on DMFar. Please use the latest reference positions from Laser cameras and alignment references.
8. Step 5 may need to iterate multiple times until the alignments converge
9. Use the Up, Down, Left, and Right buttons on DM Near and DM Far in the Laser Room Control Panel to align the laser to the reference positions.
  1. The alignment on DMFar is more important. The stats position of DMNear is sensitive
  In general, it is more important to pioritize the optimization on DM Far. The Stats position of DM near is subject
  1. to the laser beam profile, so offsets
  to
  1. of ~10 pixels in each direction
  may be acceptable
E) Beam transport alignment: HeNe
As of April 2022, we use the HeNe auto alignment for B0-B3. B4-B6 are aligned manually because they are noisy.
1. Open S20 Laser Transport Multi Profile Monitor (facet home → Matlab GUIs → S20 Laser Tools → S20 Laser Transport Multi Profile Monitor)
2. Start display and check profiles look fine (cameras are running). Unblock HeNe (button on auto align GUI) if blocked.
3. Make sure ROIs are set somewhat tightly → set Zoom ROI in Profile Monitor GUI if needed
4. Press 'Stop Alignment' (red button) on auto align GUI.
5. Set camera exposure time for beam transport cameras by pressing 'HeNe cameras' (see Figure 1, 3.)
6. Tick boxes for 'HeNe Near and Far', 'B0 and B1', 'B2 and B3'.
7. Click 'Clear References', then 'Grab References'. This might take a few seconds.
8. Click 'Start Alignment'.
9. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
For manual alignment of B4 (and B5/B6 for main beam), follow these steps:
1. Set exposure times for B4-B6 (facet home → Profile Monitor → LI20 → PyDM All Cameras or specific window)
  1. B4 ~ 4 s
  2. B5 and B6 ~ 1-2 s
2. Press 'Stop Alignment' (red button) on auto align GUI.
3. Press 'Block' under HeNe status to block HeNe
4. Open Profile Monitor (facet home → Matlab GUIs → Profile Monitor...)
5. Open B4, tick box 'Use background', press button 'take background'
6. Open B5, tick box 'Use background', press button 'take background'
7. Open B6, tick box 'Use background', press button 'take background'
8. Press 'Unblock' under HeNe status to block HeNe
9. Check on Profile Monitor window that beam is visible enough for alignment
  1. if not, set longer exposure time (step 1), then repeat steps 3-9
10. Use mirrors and references from Laser cameras and alignment references to point beam
  1. Use 'Show stats' on profile monitor for B5/6. Might have to zoom in and go by eye for B4 if noisy.
11. Once done, press 'Clear References' and 'Grab References' on auto align GUI.
12. Press 'Start Alignment'
13. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
F) Beam transport alignment: IR
Once the beam transport is aligned with the HeNe, proceed to overlap the IR with the HeNe. This assumes the IR is aligned to DMNear and Far (see D).
1. Unblock the IR beam after the MPA if not done already.
2. Align to DMNear and Far if not done already (see D)
3. Turn LSS-2 key to allow IR beam to go through transport.
4. On the auto align GUI, press the button 'IR mode'. This will stop the current alignment and opens a new window (see Figure 3)
5. Use the buttons in the first line to switch from HeNe to IR:
  1. 'Block HeNe' – drives HeNe block to 10 mm (blocked) from 8 mm (open)
  2. 'Close Iris' – sets iris to -5 mm from -40 mm (full beam size)
  3. 'Set HWP' – rotates wave plate 2 to 65 from 50 (s-pol)
  4. 'Set B0 B1 exposure' – sets exposure on B0 and B1 to 1 s (from 1 ms)
  5. 'Unblock EPS Shutter' – opens EPS shutter
6. Click 'Clear IR references', then 'Grab IR References'
7. Click 'Start IR alignment'
8. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
9. Once converged, press 'Abort IR alignment'.
10. Then follow the steps in line 4 to return settings to HeNe alignment mode:
  1. 'Block EPS Shutter' – closes EPS shutter
  2. 'Open iris' – opens iris from -5 mm to -40 mm (full beam size)
  3. 'Set HWP' – rotates wave plate 2 from 65 to 50 (s-pol)
  4. 'Set B0 B1 exposure' – sets exposure on B0 and B1 to 1 ms (from 1 s)
  5. 'Unblock HeNe' – drives HeNe block from 10 mm (blocked) to 8 mm (open)
  6. Close the IR alignment window
11. On main window of auto align GUI, click 'Clear References', then 'Grab References'.
12. Then click 'Start alignment' to resume HeNe and laser room auto alignment.
13. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
G) Beam transport alignment: Drifts and fixing alignment
As long as B4 and onwards are not automatically aligned and kept aligned, slow drifts are expected over time. B4 is the first mirror in the tunnel and sees the pointing from B3 through the penetration, which is probably the longest distance between two mirrors in the beam transport. B3 pointing (seen on B4) is affecting both the main beam and the probe. The probe line is particularly complex and suffers greatly from these drifts.
The simplest way to fix up alignment is by manually re-aligning B4 (and B5/B6 for main beam alignment). See E), second part, for instructions.
1. 1. are acceptable.
Image Added