At the EX station, the purge air supply was switched on from 09:46 until 18:16 with the highest load possible, according to WP #12001. The temperature of the mechanical room and the environment was monitored periodically.
It can be concluded, that the HVAC system was able to hold a ~5 deg F temperature difference with the outside temperature. For more details, see graph.
The temperature was rising rapidly after switching on the purge air supply. Then, a big decrease can be seen - this could have 2 reasons: (i) the sunlight just went away from the front of the building, and/or (ii) the HVAC system reacted like this.
In the end, the HVAC system consolidated the temperature at 91.4 deg F.

This whole measurement was carried out as additional information for the installation of the new purge air supplies.

TITLE: 07/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Tony
SHIFT SUMMARY: More KTP work in the optics lab, the wedge broke during work today but we have a spare. The LVEA remains in SAFE.
LOG:                                                                                                                                                                                                                                                                                                                                                                

Keita, Sheila

Summary:  We chipped the spare KTP crystal this morning, and this afternoon installed the back up spare that Rodica had shipped.  We've adjusted the roll, and the pitch angle seems better than the crystal that we removed.  So this should be ready to go into the chamber first thing Monday morning.  We have many photos from today, which will be attached and annotated to this alog later. 

Following on From Jason's alog 79319

With this placement of the damaged KTP in it's assembly, where the assembly is bolted perpendictular to the beam path, and a wave plate to mix the polarizatoins upstream of the KTP,  we have 13.5mW in the p polarized beam (see first attachment which is a diagram Paul sent us this morning), 16.3mW in the s polarized beam, and 2.3 mW in the AR surface.  This is not set up with the AOI that the AR coating is designed for, which is why the AR beam is large, we can take advantage of this to set the pitch by setting the AR reflection parallel to the table.. 

With the original KTP in place, the AR reflection isn't parallel to the table it is pitched up by 10/(530 +405 mm) about 11 mrad. The optic lab beam is hitting the KTP a little below the burned spot, which would have been on the +X side in chamber.  The burned spots are on the side closer to our alignment laser.

Before taking it out of the mount we took a variety of photos showing the damage spots position.  We did not find any indium foil in the mount, Paul had warned us that there might be indium between part 5 and part 9 of D2000038. 

As we were placing the new crystal in the mount, we left the set screws (11) that hold the peek loose, and held the piece upsidedown while we screwed in the bolts labeled #10 to hold on the aliuminum plate.  It chipped as we were tightening the bolts labeled 10 in D2000038. After some discussion with Rodica, Paul, Gabriele, we went back to the lab to take photos of the chip and try to understand how the chip happened.  We have photos showing that the crystal was proud of the top of part 5, the orientation of the black metal piece.  After we removed the black front plate, we could see that the KTP was firmly stuck in part #5, with the wedge stuck.  Keita had to push on the back of the crystal to get it loose. 

Keita made a series of measurements using calibers:

Chipped KTP: (agrees well with the drawing: E1900284)

• height on thicker side: 0.8850 inches
• heght on thinner side: 0.8845 inches
• width (center to center): 0.8870 inches
• width from one corner to the other (longest width): 0.9360 inches
• thickness: 0.5055 for thicker side

part 5: https://dcc.ligo.org/DocDB/0171/D2000567/001/D2000567_A%2B_OFI_KTP_Wedge_Holder.pdf

• side to side width of the opening for the crystal (measured on the side where the black part attaches) 0.9225 inches
• depth of the slot 0.515 inches on the deeper side.
• depth of the slot 0.458 on the thinner side
• height of the slot, including space for peek, 1.003 inches

peek:

• thickest part 0.1105 inches
• thinnest part: 0.1095 inches

total height (max): crystal + peek = 0.885+0.1105 = 0.9955 inches, smaller than 0.2mm than the height of the slot.

cratered KTP:

• height of crystal at thick side 0.8855 inches
• height of crystal at thinner side: 0.8835 inches
• width (center to center): 0.887 inches
• width diagonal: 0.9345 inches
• thickness of thicker side: 0.5095 inches

We then did a trial run (using the chipped KTP) of an approach that we think avoids the problem of letting the KTP get wedged in the holder.  We set the KTP on several wipes on the bench, and set the peek underneath it.  We then slid the holder (part #5) over this whole thing, which went smoothly, and tightened the set screws.  After flipping it over, we can see that the KTP is not proud of part #5, and it sits nearly flush to the front of the holder.  We could then easily attach the black front plate.  We decided to do this with the final spare, which had 2 small chips on the edge. 

With that spare installed in the assembly, we adjusted roll using the alignment laser that Camilla and Jason set up.  We wanted to adjust roll so that the transmitted beams were level to the table, since we know that the laser bea we started with were parallel to the table.  The roll adjustment was sticky, and tightneing the set screw tended to lower the transmitted beams.  The beams transmitted are off in yaw compared to the ones from the cratered KTP, by about 7mm/870mm + about 8 mrad.  We had difficulty seeing the AR reflected beam, but we can see a tiny beam with all the lights off (this suggest that the reason the beam was so bright before was the coating damage, not the AOI of the crystal in our set up.). At 820 mm from the KTP, the AR beam was about 1 mm too low, so it's pitched down by 1mrad. 

We think this is about as good as we can do by adjusting with this mount, so we are satisfied and will leave the KTP assembly under wipes and foil to be reinstalled on Monday.

Closes FAMIS26445 last checked in alog78733

BRS-X appears to be drifting towards the upper limit, the temperature seems stable.

Closes FAMIS26319 , last checked in alog79120.

For the out buildings there were some fans turned off and on, EX looks like a fan was repaired yesterday.

For the CS, MR_FAN3_170_1 looks like it has gotten a touch more unstable the past day, and MR_FAN5_170_1&2 is quite noisy.

Fri Jul 26 08:08:56 2024 INFO: Fill completed in 8min 52secs

TITLE: 07/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 0mph Gusts, 0mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s
QUICK SUMMARY:

• Currently getting hit by a 4.8 from Texas
• The docket for today from E2400260:
  • Reinstall KTP (1)  D2000038 assembly.  
  • Check that optics lab roll adjustment was good enough by checking beam sent to sqz path (TFP rejected beam), 
  • measure OFI throughput, and check that alignment beam is still going to both irises and SR2 center.
  • Pull out whole FS (1) D2000037 Assembly  SEE NOTES FROM PAUL BELOW
    • Remove XX
    • Disassemble XX
    • Ultrasonic clean mount to remove spatter from KTP
    • Reinstall XX
  • Transition back to Safe when done.

Dew point measurement taken this morning read at -43.4 ^oC.  Measurement taken before removing HAM6 -X door.  Some demand from HAM5, and HAM6 with soft covers on.

C. Compton, S. Dwyer, J. Oberling

This afternoon we prepared the KTP wedge assembly for swap and realignment.  Camilla had already mostly prepped a beam path for this using the beam reflected from the PBS cube in front of the Prometheus laser, but there was some oddness with the beam so Sheila and I moved one of the mirrors so we could use the beam transmitted by the PBS cube.  There was still oddness with the beam when at low power (looked like it had a bit of a halo around it), but it went away at a slightly higher power (a couple mW vs just under 1 mW).  Moving on, we aligned the beam along a row of holes and then installed the KTP wedge assembly (after Sheila wiped the area down several times with IPA wipes).  We had removed the beam dump assembly before placing the KTP wedge in the beam path, and the bolts were very tight.  It looked like the black coating on the assembly was also in the threaded bolt holes; this coating had been rubbed off by the bolts during assembly, and it looked like this was the cause of the difficulty in removing the beam dump assembly (there was coating visiblt deep in the threads but none on the outside where the bolt fully contacts the threads).  A HWP was placed in the beam so we could adjust the power in the beams transmitted by the KTP wedge.

With the KTP wedge assembly in place we found the two transmitted beams and set irises in the near and far field, 2 irises for each beam.  We also found the beam reflected from the front surface of the KTP wedge and placed an iris in this beam as well.  I placed beam dumps to block the beams so there are not unblocked beams when the laser gets turned on.  To preserve the cleanliness of the KTP wedge assembly I placed several layers of dry wipes over the assembly and then covered it with foil; I then wiped the area down again with IPA wipes.  The KTP wedge assembly is now ready for the damaged KTP wedge to be swapped with a spare and realigned; Keita and Sheila plan on starting the swap and realignment tomorrow.

I've attached several pictures of the setup and they are, in order:

1. The 2 near field irises behind the KTP wedge (with beam dump between KTP wedge and the irises)
2. The near and far field irises
3. The reflected beam iris and its beam dump
4. Another picture of the KTP wedge assembly
5. Foil covering over KTP wedge assembly (with several layers of dry wipes between the foil and the KTP wedge assembly)

NOTE: There is now a Class A assembly in the Optics Lab.  Please observe ALL posted contamination control signs when entering the Optics Lab, and DO NOT enter the far cleanroom (with the Prometheus laser on it) unless you are working on the KTP wedge assembly swap.  This assembly is going back into the vacuum envelope, so we have to do our absolute best to preserve its cleanliness.  Thank you.

Today's activities:
- The purge air dew point was measured at the purge port: (9:15 am) -43.9 deg C, so it is consistently dropping in time. Some more specifics here: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=79306
- HAM6 -X door has been removed. The O-rings seem to be intact
- The opportunity was taken for replacing the HAM6 RGA. It will be also re-wrapped with heat tapes, and after the chamber work ends, will be baked out.
- Pressures: the arms' pressures slowly dropping (probably because of the weather is getting colder). The Y-manifold pressure is stabilized around 2-3E-8 Torr.

TITLE: 07/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: KTP has been removed from the OFI and is in the Optics Lab(79315), where it will be removed and replaced.
LOG:

C. Compton, S. Dwyer, J. Oberling

This morning we removed the KTP wedge assembly (D2000038) from the OFI and moved it into the OSB Optics Lab.

We began by trying the "transport shims" that are supposed to help secure the OFI.  Unfortunately, these did not work.  The slot in the shims was not wide enough to fit around the OFI Earthquake Stop Posts we were supposed to fit them around, and the shims were too skinny (the posts bottomed out before contacting the shims).  So we had to pivot to Plan B, which was to use dog clamps instead.  This mostly worked, but the OFI still moved around enough that we decided one of us would try to support the OFI while the other turned bolts.  Camilla has some pictures of this and will post as a comment to this alog.  Even still, we managed to almost immediately dislodge one of the OSEM magnets (the one near the lone +X/+Y OSEM) as soon as we started trying to remove the KTP wedge assembly (the magnet is still stuck to the flag on the OFI, will need to have its polarity checked and be put back in place).

We first placed a teflon sheet in between the KTP wedge and the quartz rotator assembly.  Using non-magnetic tools (a titanium hex key that had been bent so it would fit in the space between the KTP and FS wedges, and a beryllium copper one that had been cut short) we attempted to remove the beam dump assembly from the KTP wedge assembly.  Camilla held the OFI and I tried to loosen the bolts holding the beam dump on the KTP wedge.  I say "tried" because the bolts are frozen in place.  We were unable to get them to move, at all.  Pivoting again, we found that the beryllium copper hex key was short enough to fit under the beam dump assembly, so we began loosening the two bolts on the +Y side of the KTP wedge assembly; Camilla had to crawl in the -X door to access the -X bolt while I held the OFI.  This worked until the -X bolt was loose enough that we could no longer fit the hex key under the beam dump assembly.  At this point Sheila used a T-shaped titanium hex key to loosen the -Y bolt on the KTP wedge (the bolt directly under the quartz rotator) while I held the OFI, and then I loosened the +X bolt.  With these 2 bolts loose we were able to lift the KTP wedge assembly enough that Camilla could fit the hex key under the beam dump assembly again.  In this way were able to slowly work the -X bolt free.  With all bolts free I carefully removed the KTP wedge assembly while Sheila held the OFI.  We Ooohh'd and Ahhhh'd at the craters in the KTP wedge for a bit and took some photos (see attached), and Camilla and Sheila grabbed some more pictures of the back side of the FS wedge (more access, and therefore better viewing, with the KTP assembly out of the way).  We also removed the teflon sheet from in front of the quartz rotator.

We ensured all of the non-magnetic tools were separate from other tools in the cleanroom, safely wrapped up the tools we would need as well as the KTP wedge assembly, and moved everything to the optics lab to start prepping for swapping and realigning the KTP wedge assembly (the beam dump assembly will have to be removed in the Optics Lab).  I've attached a few closeup pictures of the KTP; 2 are viewing the front surface and one is viewing the back surface (better view of the coating damage around the craters).  Camilla has several other pictures that she'll attach as a comment to this alog.