Dew point measurement taken this morning read at -43.6 ^oC.  Measurement taken before any activity inside chambers.  Soft covers were on HAM5 and HAM6, HAM7 is isolated.

A slow motion video of the fast shutter, firing with the high voltage driver in air, is here:  slow motion video

Thu Aug 01 08:07:40 2024 INFO: Fill completed in 7min 36secs

TITLE: 08/01 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: 1mph Gusts, 0mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

Today we'll be closing upu HAM6!

After transition to laser safe, I unlocked HAM6 ISI, did a small balance adjustment and ran some close out tfs. TFs look okay. I think SEI is ready for doors to go on.

TITLE: 07/31 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
SHIFT SUMMARY:
I know that there have been a lot of Laser trasitions done today...
But

The LVEA IS  currently in LASER SAFE.

OFI work has continued all day :

1. ✅Measure Isolation - new simpler plan suggestion from LLO (cube between SRM and OFI…)  Backup - Need Aux laser in HAM6 as LLO#58791, 58848
   1. If out of spec, adjust TGG crystal location (slots in mount)
2. ✅ Inspect/deal with beam dumps if not done already
3. ✅Squeeze beam alignment Check, AS and WFS
4. ✅Check OFI rejected PD path alog59906 KPT fwd rejected (use WP before OFI)

Before closeout 

1. ✅ Robert in-chamber pictures
2. ✅Finish testing Fast Shutter, trigger HV
3. See HAM6 closeout checklist
4. ✅ Correct OFI osem magnet(s)
5. ✅ Rebalance  OFI
6. Reinstall OFI Glass shroud
7. ✅ Re Check AS and WFS (Not checking WFS)
8. ✅ Turn on laser for final alignment check 
9. ✅ Remove all retro reflector, iris and AUX laser parts
10. Unlock ISI ( Jim is unlocking HAM5 but not HAM6)

LOG:

Ryan Crouch has Transitioned the LVEA to LASER SAFE.

Work Permit 12014

Betsy, Rahul

This afternoon, Betsy adjusted the SD magnet on the OFI and we confirmed that it is sitting correctly in it's place. Next, she inserted the AOSEM and centered it on the magnet (polarity was already checked). We also took this opportunity to take the OLC/offsets/gain for the SD aosem, which is given below,

OLC = 17000, offsets = -8500, Gain = 1.739 (30,000/OLC). This has accepted in the SDF.

The in-air transfer function measurement results are attached below (we took only 3 averages) and they look healthy for all three dof - template at /ligo/svncommon/SusSVN/sus/trunk/OFIS/H1/OFI/SAGM1/Data

We then started attaching the OFI shroud as per D11800103 - the top two, side (+X side) and front shroud has been attached. Mitchell joined us to help with attaching the top and one of the shrouds. There are two/three more panels left to be attached, which will be done once Sheila is done with the beam alignment check.

Sheila has Transitioned the LVEA to LASER Hazard.

Work Permit 12013

Sheila, Betsy, Keita, Camilla. Continuing from 79373. Measured in 2021 in the lab in 59410.

Betsy and Sheila set up of the power meter in location B of 79373 with the wave-plate rotated such that the beam is visible. Distance between OM1 and retro-mirror is ~350mm, before the fast shutter.

The retro-refection wasn't perfect. Betsy and Sheila found that the HAM5 iris centered on the forward aux laser isn't well centered on the beam retro-reflected from the mirror in HAM6. This made it hard to block the ghost beam (direct reflection, no change in polarization) without also blocking the retro-beam that we want to measure. There is also a bright rejected beam headed to ZM6 which is only there as the waveplate is changing polarization is making some of the beam rejected by the TFP.  They touched the retro mirror to improve it.

They alternated power measurements from position B (the beam that should be isolated by the OFI) and then position A (to measure the power from the laser). Used 10 seconds of statistics mode data for each with the Thorlabs power meter.

Starting measurements at 10:01 PT:

• Position B (isolated by the OFI): 1) mean 1.025uW stdev 25.55nW, Blocked/Background 809.0nW stdev 2.227nW, 2) mean 1.056uW stdev 12.11nW, Blocked/Background 845nW stdev 8nW, 3) mean 1.015uW stdev 1212nW, Blocked/Background 822nW stdev 4nW
• Position A (power from the laser): 1) mean 7.589mW, stdev 96.83uW. Blocked/Background 685.7nW stdev 12nW 2) mean 7.708mW, stdev 41.13uW 3) mean 7.742mW, stdev 47.93uW

Similar measurements by LLO in 58791 and 2021 from LHO in lab 59410.

AS_C sees this beam, measuring 360uW. It is not centered, -0.4 in Pit and -0.4 Yaw, see attached. When we set up the aux laser it was also off in this direction (-0.6, -0.6) 79300: similar enough.

Betsy and Shieal added a waveplate before the OFI in the AUX path and checked that the forward KTP rejected beam to OFI_B was seen, attached.

In parallel, we turned on the SQZ laser and checked that the SQZ dither lock was stable (0.94mW on OPO_IR_PD) with 75mW of SEED injected. Keita and I opened SQZT7 and adjusted ZM4 and ZM5 to be better centered on the irises. We still didn't have much beam on AS_C but after I further adjusted ZM4 (sdf's not saved), we could see it, see attached.

Betsy is working on replacing the osem magnet I knocked from it's correct position in 79316.

Dew point measurement taken this morning read at -43.9 ^oC.  Measurement taken before any activity inside chambers.  Soft covers were on HAM5 and HAM6, HAM7 is isolated and a bit pressurized.

Sheila, Keita, Jennie, Camilla

After practicing with the damaged Fused Silica (FS) wedge, Sheila and I installed the new FS wedge. Labeled E1900361 S/N 07 Run# P20-378, 379. We noticed some dust/fiber on the FS after install (didn't inspect before) so Keita wiped with a clean swab. Photo's after cleaning are first and second attachments.

Yesterday 79351 we found indium foil between part (3) and (5) of the FS assembly D2000037 where the (6) screw contacts. Rodica reccommended we add a new piece of indium foil. Third photo attached.

Keita installed the FS holder ot the assembly and we adjusted roll by eye. We installed the assembly onto the OFI. We reinstalled the beamdump bar (never moved dumps on it but wiped them yesterday) and the baffle bar and baffle. Baffle was installed in the same location, touching the double thick beamdump. We then unlocked the OFI and reinstalled the nominal motion limiter screws.

We then transitioned to laser hazard, the retroflection of the aux beam looked good and we checked that SRM was in it's nominal position. No reason to go to SR2.

The beam through the OFI started very (50mm?) low and was hitting the fast shutter. We then adjusted the roll of the FS wedge assembly to correct for any pitch,  it was hard to make fine adjustments and tightening the screw moved the beam. It was a little off in yaw. Keita has photos of the beam position.

We repeated yesterday's 79344 throughput power measurements with more laser power:

• Before OFI after SRM, 1) mean 9.627mW, stdev 198.1uW over 10sec 2) mean 9.862mW, stdev 289.6uW over 10sec 3) mean 9.901mW, stdev 287.8uW over 10sec
• SQZ beam power to ZM6: 1) mean 20.71uW stdev 367.3nW, Blocked/Background 200.1nW stdev 1.387nW, 2) mean 21.84uW stdev 481.9nW, Blocked/Background 251.1nW stdev 2.457nW, 3) mean 22.69uW stdev 548.6nW, Blocked/Background 228.9nW stdev 1.547nW,
• Input to HAM6 1) mean 11.10mW, stdev 306.4uW over 10sec 2) mean 11.10mW, stdev 268.0uW over 10sec 3) mean 11.50mW, stdev 270.3uW over 10sec
• Repeat before OFI after SRM @11:52PT (as laser power/polarization appears to be drifting), 1) mean 11.36mW, stdev 274.9uW over 10sec 2) mean 11.35mW, stdev 184.9uW over 10sec 3) mean 11.45mW, stdev 207.8uW over 10sec
• Repeat Input to HAM6 1) mean 11.49mW, stdev 255.6uW over 10sec 2) mean 11.46mW, stdev 217.1uW over 10sec 3) mean 11.55mW, stdev 195.4uW over 10sec
• Sheila will calculate the throughput and post in a comment.

The rejected beam to SQZ goes through ZM6 baffles, and around the middle of the HAM7 GV.

Sheila then headed to SR2 and checked that the beam was centered in pitch and yaw.

Sheila, Keita, Betsy, Camilla

In the last power measurements in 79313 we were loosing 25% through OFI and another 15% from lost through incorrect polarization through the TFP.

Today's measurements:

• Before OFI after SRM, 1) mean 5.212mW, stdev 40uW over 10sec 2) lights out mean 5.134mW st 35uW 3) lights out mean 5.098mW stdev 39uW, mean
• Input to HAM6 1) mean 5.173mW stdev 32uW, 2) mean 5.199mW stdev 40uW 3) mean 5.066mW stdev 23.4uW
• SQZ beam power to ZM6: 1) mean 10.09uW stdev 78nW, Blocked/Background 1.175uW stdev 0.3nW, difference 8.915uW 2) mean 9.92uW stdev 64nW, Blocked 1.16uW stdev 0.5nW, difference  8.76uW  3) mean 9.944uW stdev 76nW, Blocked/Background 1.185uW stdev 16nW difference 8.759uW
• Max power out of laser collimator at iris with 220mAmp setting, 38mW+13mW dumped ~50mW

From the mean of these measurements Sheila and Louis calculated the rejected ratio (power sent to ZM6) is 0.17 ± 0.002%. The transmission through to HAM6 is 99.96 ± 1.45%. The sum of these is 100.13%, which is within the margin off error.

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.

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

We aligned the AUX laser in HAM5 so that it is roughly centered on OM1 AND is retroreflected by SRM. We haven't checked anything else.

Retroreflection was measured/evaluated using an iris right in front of the AUX laser launcher telescope. First the iris was well centered relative to the input light (1st attachment shows the scattering around the iris when it was closed down a bit), and we used a steering mirror and a beam splitter installed between the AUX laser and the SRM to get the SRM reflection coming back to the iris AND SRM transmission hitting the center of OM1 without touching SRM. It was easy. 2nd attachment shows the return beam on the iris after REALLY closing down the iris so the return beam clips on it. Centering on OM1 was based on just eyeballing using a sensor card.

We don't know where on the SRM or OFI the beam was (no easy reference). It seems that the beam was seen by ASC-AS_C but not centered on it.

The above was done before we were informed about a large ISI/HEPI rotation in YAW (alog 79272) so probably we'll do it again after moving SRM to compensate to get closer to the right alignment quickly (rather than walking the beam from where we are now slowly, checking the OM1 centering and SRM retroreflection many, many times).

In the end, we should make the SRM transmission hit the center of AS_C, make the beam retro reflected by SRM, and make the SRM reflection hit the center of SR2, all at the same time. For that, probably we'll have to make a minor adjustment to SRM.