Page History

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

Assumption is that the oscillator and Regen are running.

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, and that the auto aligner is being used as much as possiblethe 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 well.

Preparations

in 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

Start up/warm up

Turn on PreAmp (Flashlamp and Q-Switch)
Turn on both SAGAs (shutters closed)

PreAmp and MPA alignment

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 the Pre-amp pump laser by pushing both the Flashlamp and Q-Switch buttons on the remote.
Turn on both SAGAs 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 the auto-aligner GUI (FACETHOME→Physics Apps...→S20 Laser Tools→S20 Laser Auto Alignment), the panel in Fig. 3 should open.
Press Stop 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 Laser Auto Alignment), see Figure 1.
Press 'Stop Alignment' (red button). This will stop any scripts running on other machines.
Set camera exposure time for all laser cameras by pressing 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:
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 two sets of laser cameras: Pulse Picker and Regen Out 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)
: Global value around 5 pixels, MPA Near/Far in the end around 20 but initially much higher ~100
1. .
Tick boxes for first three sets of laser cameras: '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.
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. Open SAGA shutters.
DMNear and Far alignment
Beam transport alignment: HeNe
As of April 2022, we use the HeNe 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. Tick boxes for 'HeNe Near and Far', 'B0 and B1', 'B2 and B3'.
6. Click 'Clear References', then 'Grab References'. This might take a few seconds.
7. Click 'Start Alignment'.
8. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
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.
1. Unblock the IR beam after the MPA if not done already.
2. On the auto align GUI, press the button 'IR mode'. This will stop the current alignment and opens a new window (see Figure 3)
3. Use the buttons in the first line to switch from HeNe to IR:
  1. Block HeNe
  2. Unblock EPS Shutter
  3. Set exposure to 1s
  4. Set iris to -5 mm (from -40 mm)
  5. Set wave plate 2 to 65 (from 50)
4. Click 'Clear IR references', then 'Grab IR References'
5. Click 'Start IR alignment'
6. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
7. Once converged, press 'Abort IR alignment'.
8. Then follow the steps in line 4 to return settings to HeNe alignment mode:
  1. Block EPS Shutter
  2. Unblock HeNe
  3. Set B0 and B1 exposure to 1 ms
  4. Set iris to -40 mm
  5. Set wave plate 2 to 50.
  6. Close the IR alignment window
9. On main window of auto align GUI, click 'Clear References', then 'Grab References.
10. Then click 'Start alignment' to resume HeNe and laser room auto alignment.
11. Monitor the log to make sure that the offset tolerances were set appropriately and that the auto aligner does its job.
1. 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.
2. Verify the fluorescence profile looks okay on S20Launch (see reference above).
3. 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.
D) DMNear and DMFar alignment
1. For tunnel work, manually insert the RP attenuator. For full power laser, remove the RP attenuator.
2. If the RP attenuator is at the "out" position, insert ND flippers in the laser room:
  1. Flip the full power laser ND filter into the common beam path of the DMNear and DMFar cameras.
  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 Main-amp so that the Ti:Sapph laser can propagate through the DMNear and DMFar beam path.
5. 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 to the laser beam profile, so offsets of ~10 pixels in each direction are acceptable.
Image Added