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.

PCAL has had a Paper Log of all the measurements taken from Spring2023 to Summer2024.
Since Jun24, We have switched over to a google Doc PCAL-Lab-Log, a new log will likely be made by the scripts in the near future.

Closes FAMIS#27794, last checked 79168

TCSX: At 30.3. No water added.

TCSY: At 10.5. No water added.

No leak in water cup

FAMIS 26270

Laser Status:
    NPRO output power is 1.822W (nominal ~2W)
    AMP1 output power is 65.16W (nominal ~70W)
    AMP2 output power is 138.0W (nominal 135-140W)
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 15 days, 21 hr 10 minutes
    Reflected power = 18.79W
    Transmitted power = 108.0W
    PowerSum = 126.8W

FSS:
    It has been locked for 7 days 17 hr and 43 min
    TPD[V] = 0.7268V

ISS:
    The diffracted power is around 2.4%
    Last saturation event was 8 days 18 hours and 55 minutes ago

Possible Issues:
    PMC reflected power is high

Thu Jul 25 08:08:24 2024 INFO: Fill completed in 8min 20secs

Jordan confirmed a good fill curbside.

TITLE: 07/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 2mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY: We went to laser safe yesterday afternoon and are ready for today's work

Today's plan:

• Move the AUX laser out of the way
• Door crew removes HAM6 door in the morning
• In the afternoon: Secure the OFI and remove the KTP wedge assembly (following the written steps and safety precautions in the googledoc)

Jason, Jenne, Camilla, Keita, Francisco, Naoki, Sheila. (Please see Francisco's alog for more details 79300)

Today we got the alignment laser set up and the sqz beam checks done in a way that we think is good enough to move forward with removal of the KTP tomorow.  There are more detailed notes in other alog drafts, and photos coming. 

We found this morning that the beams were not where they were left last night on the OM1 + retro reflection irises.  We decided that this was likely due to the wobbly mount with sticking knobs that the steering mirror was in, this would change the alignment from being touched, and sometimes turning the knob did not adjust the alignment because the knob wasn't engaged.  We decided to swap this mount out which took some time, but after that things went smoothly, and with about 3 iterations we were able to center the beam on SR2.  We then did a quick check of the squeezer beam, which goes through the OFI and returns to OM1.  We got some cool photos of showing a hole in the middle of the beam; we intentionally set it's alignment to go through the most recent crater. 

We are ready to go to laser safe, and the door crew plans to take HAM6 door off in the morning.  After that we will remove the KTP assembly.

Camilla, Jason, Jenne, Keita, Sheila, Francisco, Naoki

Summary: We are done for AUX laser alignment and power measurement of AUX laser. SQZ beam got to OM1, but we did not do power measurement due to noisy seed dither lock. The following are a mixture of notes between Camilla, Francisco, and Naoki regarding the changes done today:

Aiming for 2 1/4" above EQ stop as 4" between vertical stops and the center of SR2 optic is 5.5mm above center line of EQ stops.

At start of the day, someting had drifted (mainly pitch), re-centered AUX laser on irises.

*Iterating moving auxiliary laser mirror and beamspiltter to center in om1 and retroreflection irises.*

Checking position at SR2:

• 1 1/4 in above EQ stop
• 1cm in +x from the center

Swapped the AUX laser steeing mirror to a better optic mount and not woberly perdistal, we are blaming this for our drift.

Jenne also adjusted SRM sliders to yesterdays values.

*Iterating moving auxiliary laser mirror and beamspiltter to center in om1 and retroreflection irises.*

Checking position at SR2:

• 1 1/2 in above EQ stop
• 1cm in +x from the center

Moved SRM osems from (175, 140) to (50,190). In pitch moved -125urad from 175 to 50 on osems. In yaw moved +50urad. this was 140 to 190 on osems
Aiming to center the beam on SR2

*Iterating moving auxiliary moving mirror to center in om1 and retroreflection irises.*

Checking position at SR2:

• 2 1/4 in above EQ stop
• 3/4 in from +x EQ stop
• yaw got "worse"

EQ stops are 2 1/2 in away from each other; center is 1 1/4 in from horizontal EQ stop

Will do 100 microrad in -YAW, then check retro in OM1. -100urad in yaw is 190 to 90 on osems

*Iterating moving auxiliary moving mirror to center in om1 and retroreflection irises.*

Checking positions at SR2:

• 1/2 in away from horizontal EQ stop
• Went wrong direction

In yaw going +300 urad. This is 90 to 390 on osems.

*Iterating moving auxiliary moving mirror to center in om1 and retroreflection irises.*

Checking positions at SR2:

• 1 1/4 in away from horizontal EQ stop (nice.)
• 2 1/2 in above bottom of EQ stop

*LUNCH BREAK*
 

Sheila back to SR2;

• 2 1/2 inch above bottom of EQ stop
• yaw is still good

earlier today SRM P moved from 179 to 50. 1 1/4 inch move on SR2

Moved 1/4 inch backward. moved SRM P from 50 to 76

Sheila is happy with SR2 centering.

Jason is setting iris on OM1. Beam on OM1 ugly? due to crater on OFI?

ASC_AS_C P -0.6 Y -0.6

open GV for HAM7. send SQZ beam. seed dither lock is very noisy.

SQZ beam is close to AUX laser?

AUX power measurement

• 1.72mW before SRM
• just after SRM 0.605mW
• before OM1 0.380mW
• 0.45mW after TGG before TFP

Dew point measurement taken this morning by Jordan, read at -43.9 ^oC.  Some demand by HAM5/6, small crew at work.

TITLE: 07/24 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY: The OFI team was able to get the AUX laser aligned and verified that the SQZ beam can get to OM1. Tomorrow morning first thing we will be transitioning the LVEA to laser safe and continuing the OFI work by taking the KTP out and taking the HAM6 -X door off.
LOG:

- Continuing work on aligning AUX laser

- Aligning sqz beam

- Getting ready to transition to laser safe

Keita, Jennie W

Keita and I worked out the distance behind SRM we have to place the AUX launcher to match the beam radius the IFO beam normally has on SRM on its way into the OFI.

This is based on measurements of beam profile Keita made in the optics lab with the aux laser mounted with a collimator on it.

The code used to do this is saved in ligo/home/jennifer.wright/ModeMatching/beam_diverg.py

The graph attached shows the measured points in orange and the fitted points in blue.

FAMIS 21009

The stabilization trends are especially interesting this week; PMC reflected power is steadily increasing while transmitted power (along with RefCav transmission and ISS diffracted power) is decreasing. This is particularly interesting as we thought this behavior might disappear when we swapped in the new PMC.

Sam and I have been investigating a ~40 Hz peak in the HAM ISIs and PEM accelerometers, first noticed by Camilla and Sheila in alogs 79001 and 78879. Jim also investigated and suggested the peak may be caused by gain peaking from the isolation loops (alog 79145). The peak is strongest in HAMs 2, 6, and the LVEAFLOOR YCRYO Z accelerometer. We tracked the first appearance of the peak to May 20th. We've found there are actually two peaks roughly 0.2 Hz apart, which drift a bit in frequency from ~39.45 Hz (20/05/24 16:00 UTC) to ~40.2 Hz (20/05/24 22:00 UTC), measured from the point between the two peaks (see 1st attachment). The peaks consistently remain about 0.2 Hz apart in frequency but they do not always have the same magnitude ratio, even between channels measured at the same time (see 2nd attachment). Overall, the peaks vary in magnitude, occasionally disappearing altogether, but we have yet to find a time when one peak disappears and the other doesn't (see 3rd & 4th attachments for peaks disappearing and reappearing, respectively). We'll continue looking into surrounding peaks and the coherence with DARM.

16:09 Tue 23 July 2024 PDT the atomic clock jumped to +0.42S out from the Timing system.

This is the third time this has happened in the past month. Prior to that it had only happened once in the past year, on 4th May. Here is a table of the atomic clock out-of-syncs for the past year

I have extended the timing comparator's tolerance to 0.9999999 seconds to 'green up' the corner station timing.

Wed Jul 24 08:05:48 2024 INFO: Fill completed in 5min 44secs

Jordan confirmed a good fill curbside.

Genevieve and Sam asked about HAM1 and HAM2 motion around 40 hz. I hadn't look in detail in this frequency band for a while, this is typically higher frequency than we are worried about with ISI motion. But it turns out HAM2 is moving a lot more than HAM3 generally over 25-55hz, and particularly around 39hz. It looks like it might be due to gain peaking from the isolation loops, but could also be from something bad in the HEPI to ISI feedforward. The extra motion is so broad I don't think it's just one loop has a little too much gain, so I'm not sure what is going on here. 

First image are spectra comparing the motion of the HEPIs for those chambers (HAM2 HEPI is red and HAM3 is blue) and the ISIs (HAM2 ISI is green, HAM3 is brown). The HEPI motion is pretty similar, so I don't think it's a difference in input motion. HAM2 is moving something like 10x as much as HAM3 over 25-55hz. The sharp peak at 39 hz looks like gain peaking, but I'm not sure that explains all the difference.

Second plot shows the transfer functions from HEPI to ISI for each chamber. Red is HAM2, blue is HAM3. The 25-55hz tf for HAM3  is not very clean probably because HAM3 is well isolated. HAM2 tf is pretty clean, it makes me wonder if maybe something is messed up with feedforward on that chamber. Maybe that is something I could (carefully) fix while other troubleshooting for the detector is going on.