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: Camera 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 laser 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: Check Chilled Water Load.
Check for any other alarms:
1. LSS control panel → Interlock Status Screen, see Figure 1.
2. LSS control panel → Details for the FEA LSS-2 (see Figure 1, only matters for laser work in the tunnel).
3. Regen signal delay box → Error light on the top of the front panel, see Figure 2.
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 EPS transport shutter is in (FACETHOME→Laser→LI20 Low and High buttons, green means the EPS shutter is inblocking 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 align -aligner GUI (FACETHOME→Matlab GUIs→S20 FACETHOME→Physics Apps...→S20 Laser Tools→S20 Laser Auto Alignment), the panel in Figure 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 3 SET EXPOSURE in the Laser Room Control Panel (bottom right).
Click the Expert... button button in the auto-aligner. This opens a new window (see Figure 4).
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. Start with 50 and reduce to 10 after the alignment convergesSet to 50.
2. The bottom box is the tolerance for the steering into the Main-amp. Start with 150 and reduce to 30 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.
Open S20 Laser Room Multi Profile Monitor (FACETHOME→Matlab GUIs→S20 Laser Tools→S20 Laser Room Multi Profile Monitor).
Start display and In the laser control panel, check profiles look fine (see reference image below), cameras are running, and laser is visible .Image Removedon the first seven screens and S20 Launch:Image Added
Verify ROIs are set somewhat tightly (see match the above image), if the full camera ROI is visible see Procedures to Fix Common Issues. 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 S20PreampOut, S20MPANear, or S20MPAFar (see image below for an example)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 Clear References then Grab References. This might will take a few ~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 S20PreampOut, S20MPANear, and S20MPAFarS20 Preamp Out, S20 Main Amp Near, and S20 Main Amp Far, click Stop Alignment (red button).
Insert image of the multi-profile monitor with badly aligned beam
Tick boxes for first three sets of laser cameras: Pulse Picker and Regen Out, Preamp Near and Far, and MPA Mainamp Near and Far.
Click Clear References, then Grab References. This might will take a few ~30 seconds. A message will be printed in the log saying grabbing is completed.
Click 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. 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.
Reduce max offset tolerance in expert panel once alignment is close
1. .
Open SAGA shutters by clicking Open on both control computers.
Verify the fluorescence profile looks okay on S20Launch (see reference multi-profile monitor above).
Check the energy on the power meter at the output of the Main-amp.
1. Typically expect around 600mJ, as low as 500mJ is okayShould be above 600mJ. Any lower than 500mJ and 600mJ, tell the laser is due for FACET laser contact so they can do a tune-up.

D) DMNear and DMFar alignment

For tunnel work, manually insert the RP attenuator. For full power laser, remove the RP attenuator.
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. Install the full power ND filter before the lens in the InjNear and InjFar camera line.
3. Install the full power ND filter in the wavefront sensor beam path.
4. Flip the ND filter in front of the wavefront sensor to the in position.
Verify the transport shutter is still blocking the laser (Laser Room Control Panel→Transport Shutter).
Unblock the laser after the Main-amp so that the Ti:Sapph laser can propagate through the DMNear and DMFar beam path.Open a profile monitor (FACETHOME→Matlab GUIs→Profile Monitor) for DMNear.
Check Show Stats in the profile monitor.
Launch the laser aligner (FACETHOME→Matlab GUIs→S20 Laser Tools→S20 Laser Aligner) and select DMFar, see Figure 5.
1. It is helpful to change the circle size to 50px.
Adjust the energy waveplate as needed to see the beam in both windows (FACETHOME→Laser→LI20→Infrastructure→XPS moc-la20-ls24, channel 1, see Laser Room Energy Attenuator for more info)
Use the Up, Down, Left, and Right buttons on DM Near and DM Far in the aligner Laser Room Control Panel to align DMFar to the reference position.
1. A step size of 0.1 is a good starting point.
Set the aligner to DMNear, use the Up, Down, Left, and Right buttons in the aligner to align to the reference position in the stats window.
1. Look at the beam in the profile monitor stats window, not in the aligner window.
2. The refence position is recorded at Camera Alignment References.
Repeat step 7 and 8 as needed until the alignment converges.
the laser to the reference positions.
1. The alignment
In general, the alignment
1. 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.