TITLE: 03/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: GV7 is still broken and will not hard close, HAM1 vent prep work, the PSL incursion was completed, and the BHSS work continues in the Optics lab.
LOG:

• 19:19 UTC Tony keyed off TCSY

J. Kissel, M. Pirello

While in SUS-R2 and thinking SPI, and looking at the proposed rack layout from G2401479, and accounting for all the SUS (BBSS, LO1, LO2) that's incoming for O5 -- I found that SPI can have a bit more space if we just move the SUS-PR3 optical lever whitening chassis up 5 U-heights from "32" to "27." I put the u-height in quotes because this is an old style rack with the u-heights labeled from top down, rather than the bottom up per industry convention. I would have and could have gone higher, but the 27 slot already had mounting clips in it, so I went there. We can go as high as "25" if need be in the future.

Pics of before vs. after are attached.

F. Clara, J. Kissel, S. Koehlenbeck, J. Oberling, M. Pirello
D2400110

Today we picked up where we left off with the install of SPI into H1. 
Where we last left things, we'd installed a new SPI pick-off of ALS/SQZ beam in Apr 2025 (see ECR E2400083 and results in LHO aLOGs 83989, 83996, 83978). Back then, we had ended the work with the input to the fiber collimator within the PSL dumped.

With Jason and Sina in the PSL, we confirmed that the SPI path was still blocked. 

However, we also realized/remembered/confirmed that the entire ALS/SQZ/SPI path had 25% less power -- We've been running the PSL at lower power allocation downstream of the PMC since Sep 2025 to prevent issues we'd found with the currently installed EOM after a power outage triggered a dust monitor to spew out dust into the PSL (see that saga in e.g. LHO:87109 LHO:86966). They found the power at the SPI pick-off was 140 [mW] instead of the 188 [mW] we left in Apr 2025 (see LHO:83996).

(Using labels in the half-up-to-date drawing D1300348)
Jason and Sina rotated ALS-HWP2 upstream of ALSPBS01 to restore the nominal 50 [mW] into the ALS/SQZ pick-off and ~200 [mW] (190 [mW] measured). This means there's ~50 [mW] less out to ALS / ISCT1 than before today.

Then with the SPI pickoff still dumped, we installed a 30 [m] patch cord*** from the PSL optical table, out the mouse hole between the +X wall of the PSL enclosure and HAM1, then up running along the upper racks to waterfall down at SUS-H2. The fiber sits within the typical orange tubing. Per D2400110, this is SPI_PSL_001, and it's labeled as such on both ends.

After install, I connected the SUS-R2 end to a Thorlabs S121C power meter with S120-APC2 fiber adapter. 
With this installed (making the system laser safe at SUS-R2 end), Jason/Sina unblocked the SPI pickoff input. 
With 190 [mW] in, we measure 187 [mW] out on the other end. 98% transmission, pretty excellent. Almost unbelievably excellent but we weren't rigorous with our uncertainty and systematics.

Happy with this result, we then blocked the SPI path again, and re-capped the SUS-R2 end for final dressing in the racks.
We'll unblock again when we're read to connect it to the Laser Prep Chassis.

***Patch cord details:
Manufacturer DIAMOND
DIAMOND Part Number: ENS/1094388
Customer Part Number: 9711228
Patchcord SM L=30 PM
2xFC 2mm APC (i.e. 2mm narrow key FC/APC on both ends)
tran 6,6/125/245 PAND 980nm



 

WP 13105
WP 13113

During the last two days CDS EE has completed the following:

1. SPI Optical Fiber pulled from the PSL enclosure to SUS-R2
2. Heliax cable pulled from ISC-C3 to SUS-R2, part of SPI
3. Two Heliax cables pulled from ISC-C4 to ISC-R2, part of JAC
4. Cabling disconnected to IOT1 and ISCT1

This completes dirty work over HAM1 and HAM2. In the next two weeks, will close out work in SUS-R2 before HAM3 is vented.

List of items needed for SUS-R2:

1. Install power supplies in CER Mezzanine
2. Terminate power cables and install junction box
3. Terminate Heliax cable
4. Test and install two SAT Amp Chassis
5. Installation of DC sequencer
6. Install QOSEM Sat Amp
7. Pull cabling from SUS-R2 to HAM3
8. Installation of SPI electronics

F. Clara, J. Kissel, J. Oberling, M. Pirello, T. Sanchez, and R. Thompson

S. Muusse, C. Compton

0920 QCL unit failure summary:

We were beam profiling the laser and I had the profiler ~8” from the laser head, with a steering mirror to steer onto the scanner. Laser was at 1A. I blocked and unblocked the beam but as it was unblocked there was a beep and there laser controller turned off with message “LD output voltage protection was tripped”.

I then turned controller off and back on again with power down to 0.5A and it would not turn on.

Camilla then came into the lab, we turned off and unplugged controller. It was turned on again, would not turn on. Remembering LLO's issues, on the Temperature Protection screen we eased the +-5 deg requirement to +-6. Laser then appeared to turn on with “laser current reading 0.500 A” and “laser voltage reading 10.440V”, temperature 25deg. However no beam was coming from the laser.

We then turned off and on laser. Again appeared on but no beam, slowly turned up current from 0.5A towards 1A, at 0.84A controller beeped with “LD output voltage protection was tripped” message again.

QCL Unit q-parameter dependance on laser temperature:

Unit failure happened while profiling the laser to check if the q-parameter of the QCL has a temperature dependence. This profiling was done largely at a 23mm offset with one point near the waist. However, there was not an opportunity to take more measurements around the waist in this new data because of the failure which may cause some inaccuracies in the fitted q. I used a non linear fit where M2=1. This is consistent with the fitting by Matt. His measurements were completed at 20 deg but after advisement from thorlabs we have increased operating temperature to 25 deg. 

With the new q factors there is slightly better agreement between the fitted q-parameter for L2 and the model.

Vertical

Horizontal

Wed Mar 25 10:11:55 2026 INFO: Fill completed in 11min 52secs

Sheila, Camilla

While we had good green (20) and IR (1) FC flashes, we had to move 100urad in ZM3 positive PIT to get any light on SQZT7 OPO IR PD, see -2h30 on screenshot.

We then walked ZM1 and ZM2 both in negative PIT (which seems a bit weird but worked) until we only had to move ZM3 13urad to get light on SQZT7. However in doing this move, we lost the majority of IR light and some green light, see t-cursor #1 of screenshot. I injected the SEED beam at this point and the IR FC camera looked again like a strange cross or swallow bird.  I hoped to move ZM3, FC1 and FC2 to bring back IR light but wasn't able to.

I was able to get good green flashes simultaneously with SQAT7 IR light but then I had no IR FC light,  see t-cursor #3 of screenshot, 22:35UTC.

Vicky reminded us of 2022 when we had to pico to get FC green/IR co-resonance: 66017, 66281

TITLE: 03/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.23 μm/s 
QUICK SUMMARY:

• The JAC and IMC were held DOWN/OFFLINE overnight (IOT1 is disconnected)
• Test stand craning, cabling, SPI, and BHSS work continues
• The CEBEX workshop continues in the front MPR

The JAC seems to be failing to lock. I'm not sure why, but since it's just scanning I assume it's fine for the night. But, if someone with more JAC experience thinks it's useful to log in and set it to DOWN for the night, that would be good.

TITLE: 03/24 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Hard closing GV7 continues (no luck today).  New platform craned into place between BSC2+3.  Filter Cavity gate valves opened for more Squeezer alignment.  Lots of cable/fibers pulled in the LVEA.  Optics Lab was busy with Team SPI & Team BHSS work (as well as Team CHETA lab next door).

LOG:

• 1442 LVEA technical cleaning begins (kim, nellie)
  • 1550-1630 break 
  • 1630 back out to LVEA (kim,nellie)
    • 1712 nellie out
    • 1749-1841 kim out, and then back in the lvea one more time from 1841-1916
• 1457-1507 Closing Filter Cavity GVs (total of 6) [jodan]
• 1503 Untripping Hardware Watchdog (jonathan)
  • did not work but couldn't reset
  • fil check wiring?
  • may have to boot
  • it got booted during Dec power outtage 
• 1508 Prepping for "furniture moves" & craning:  main work today is a new platform between BSC2 & 3 probably this morning (randy)
  • 1526-1552 Mitch joining 
• 1525-1727 Norco LN2 @MX CP6
• 1540 SQZ bay clean-up & TCSy laser power ON (camilla)
• 1542 Getting big cable spool ready for cable pulling (fil, tony, randy)
• 1605 Cable pulling begins! (fil, tony, marc)
  • HAM1 HAM2 taken to DAMPED
  • 1842--break for lunch, most cables run.  Dressing cables remains (marc)
• 1611-1742 Locking HEPIs:  HAM3, BSC2, BSC3 (jim)
  • Above chambers taken to DAMPED
  • Betsy asked for HAM1+2 to be added as well!
  • (If they are tripped, leave them that way since there is lots of activity out there anyway.)
• 1612-1632 PSL anteroom prep to cover hardware for HEPA fan replacement (jason)
• 1629-1858 BSC2/3 platform (randy.mitch)
  • This concludes craning WITH a load. Platform still rigged to the crane as Randy gets ready to secure it in place.  But now craning loads over the Filter Cavity Beam Tube is technically complete (Randy notifying Betsy)
• 1704-1728 Picking up battery charger part for scissor lift (chris)
• 1737-1920 Norco LN2 truck delivering to EX's CP8
• 1745-1929 BHSS laser hazard alignment in optics lab (elenna, oli)
• 1752-1836 ergo arm tests (ibrahim, ryanC)
• 1750-1811 Jenne tour in CR
  • 1811-1904 Moving to LVEA with small group
• 1811-1828 Maggie Mt. Adams Middle School (8th grade) tour
• 1853-1912  transition FCES to safe (camilla)
• 1907-1920 Filter Cavity mini-gate valves closing (gerardo)
• 1931 Finish off cable pulling (fil, marc)
  • Switching to SPI optical fiber 
  • disconnecting some cables from HAM1/2 in-air tables
• 1941-2135 Secure platform (& then disconnect off crane) [randy]
• 2003-2014 Quick cable check for BHSS (oli)
• 2005 Gathering up gas containers in lvea for GV7 (travis)
  • 2103 Joining travis for GV7 work (gerardo)
  • 2225-2259 joining VAC crew at GV7 (jordan)
  • 2306 no luck on GV7's hard close (travis,gerardo)
• 2034-2047 Packaging up the ERGO Arm after earlier tests (ibrahim)
• 2037 SPI layout work (jeff,sina, bram)
• 2043 Optics Lab and LVEA walkabout (betsy)
• 2056 Tracter w/ Loader & back hoe heading to CEBEX site
• 2118-2239 Inventory C3 covers in Cleaning Room (ibrahim)
• 2128-2229 BHSS work (elenna,oli)
• 2210 CHETA table work (sophie)
  • 2234 camilla joining

J. Oberling, R. Crouch

In talking with Calum about the upcoming pre-deintall BS measurements, I realized that in the middle of JAC install I completely forgot to write an alog about the WBSC2 support tube FARO survey Ryan and I did at the beginning of February.  So, here it is.

Following the same procedure we used to survey the support tubes for WBSC3 and the +X ends of WBSC2 (alog 88620), we surveyed the -X WBSC2 support tube ends.  The results are shown in the 3 attachments; the first 2 are in the LHO Global Coordinate system and are the images I will be discussing.  The 3rd attachment contains all info from the first 2, but in the Corner Station building Local Coordinate system (included for completeness; for more on LIGO coordinate systems, see T0900340).  The first attachment shows the surveyed locations of the support tube ends, while the 2nd shows information regarding the midpoint location of the support tubes and their angles w.r.t. the IFO axes (the line shown represents the centerline of the support tube created from one end point to the other; the Nominal column (Nom) comes directly from the CAD model, while the Measured column (Meas) is our measured data.  Some interesting things to note here:

• Both support tubes are shifted in the -X direction, with the +Y support tube shifted 2.3mm more than the -Y support tube.  This is seen in the Midpoint X row in the centerlines image (2nd attachment).
  • This implies a CCW yaw of the WBSC2 cartridge assembly, in addition to the -X position shift
  • Averaging out the shift, this implies a -2.6 mm shift in the X axis position, and a 1.36 mrad CCW yaw
• My expectation was to find the support tubes too low in their Z axis position by ~2.5mm, but that is clearly not the case.
  • The BS SUS is the same length as the QUAD SUSs, but the BS sits lower in the coordinate system than the QUADs do (-82.9mm vs -80.0mm); this difference was to be made up with HEPI (i.e. shifting the support tubes lower), since physically making the BS SUS longer isn't exactly practical
  • The support tube end survey in the 1st attachment show the ends are not lower by ~2.5mm as expected, but rather fairly close to the nominal Z axis position
• No real comments re: Y axis position, this looks good

Now keep in mind that the support tube locations may not be indicative of a misalignment of the BS optic itself.  When we installed this we only cared about putting the BS where it needed to be, and HEPI (and by extension the support tube ends) was wherever it (they) needed to be to support that.  We will be taking measurements of the BS SUS cage and the optic itself once the corner is vented (likely to be one of the 1st activities after the vent), and we'll know more about the location of the BS optic once we have done so.

(Travis S., Jordan V., Richard M., Gerardo M.)

Last Friday we tried to "hard close" GV7, but we only achieved a "soft close" status.  After looking at the system that uses instrument air at the gate valve, we did noticed that the solenoid valve to "open" and "close" the gate valve was "leaking" air, lots of instrument air, to fix the air leak we decided to replace the solenoid valve with a new one.
Then when it was time to "hard close" GV7, its pressure regulator broke, we were not able to open the regulator.  We ordered a couple of new regulators and should be here on Wednesday.  Meanwhile we are going to "hard close" the gate valve using a bottle of nitrogen.
Attached is a photo of the broken regulator, yes the knob is off, but the metal piece within is free floating and not able to do its job.

We previously reported that the wiring to ground on the OMCA DCPD dsub9 cables seemed odd, see 89562. There appears to be two conflicting diagrams of the pin wiring, D2200276 and D2300119. Neither of these diagrams follow the correct pin naming practice either.

Today, Oli and I checked the ground connectivity for the OMCB DCPD dsub9. The case ground is wired to what is labeled pins 6 and 9, according to both of the diagrams above and also proper convention. However, this is different from OMCA, where the case ground is wired to pins 2 and 5 (following the incorrect naming of the diagrams above), or pins 1 and 4 (following correct naming conventions).

So either way, we have two different wiring set ups for OMCA and OMCB. We have only checked the ground pins so far, and it seems like we should confirm the cathode and anode wiring as well.

To summarize:

- we have two different diagrams for pin wiring

- OMCA and OMCB are wired differently from each other

- the diagrams are not following proper pin naming convention which is making this more confusing

R. Crouch, J. Oberling

Yesterday we began measuring the locations of the vacuum chamber support tube ends using the FARO laser tracker.  We started with the support tubes for the WBSC3 chamber and the +X ends of the WBSC2 support tubes as these were the most readily accesible.  The remaining support tubes in the LVEA (WBSC1, WBSC2 -X ends, and all WHAM chambers except WHAM7) have iLIGO-era PEM Interface Plates on them that block the support tube; some of these plates have undocumented spacers between them and the support tubes they are attached to, meaning we cannot accurately locate the support tube end w.r.t. the PEM interface plate and therefore making an accurate measurement of the support tube location impossible.  As an aside, Jim is in the process of removing these plates from the chambers (so far WHAM3 and WHAM4 are complete, WHAM1 and WHAM2 are 75% complete), so we can get at these support tube ends as the opportunity arises (he will then reinstall these plates, as they make for very convient mounts for dial indicators).

Measurement Method

This is a fairly straightforward measurement, but there is a somewhat subtle "gotcha" that needs to be accounted for to get an accurate measurement.  But first things first, we aligned the FARO to the LVEA's Building Coordinate system using our red alignment nests, then applied the X and Y axis rotations required to align the FARO to the site global coordinate system (see T0900340 for a brief overview of the coordinate systems in use).  We then loaded CAD models of the support tubes, that Ryan downloaded from the SolidWorks vault with each model in the site global coordinate system, into the FARO's control software, PolyWorks.  PolyWorks automatically reads the coordinate system information contained in the CAD files and places these models in position w.r.t. to the site global coordinate system.  This gives us nominal locations of the support tube ends, a guide for our measurements, and also a nice visual reference for where everything is positioned.

Now for the "gotcha."  The physical support tubes have a hole in the center of each end that is not represented in the CAD model, and this hole is large enough that the FARO target (a Spherically Mounted Retroreflector, or SMR, with a 1.5" diameter) sits slightly inside the hole.  This means that when you're taking a measurement of the center of the support tube end using this hole the SMR is not measuring the location of the actual support tube end, it is a few mm inside of it.  To account for this we did the following:

1. Use the SMR to get the coordinate corresponding the the axial length of the support tube on either side of the end and calculate the average (to remove any yaw in the support tube)
   • Using WBSC3 as an example, the support tubes lie parallel to the y-axis.  So we touch the SMR to either side of the support tube and record the y-axis coordinate, then calculate the average
   • We do this for each individual support tube end, as each one is slightly different
2. Use the SMR to get the same coordinate, but this time with the SMR sitting in the center of hole of the support tube
3. Calculate the difference between the two, to get the offset required for an accurate measurement
4. In the PolyWorks software:
   • Use the CAD model to create points representing the center of each end of the support tube
   • Create a line between each end point, representing the theoretical centerline of the support tube
   • Create a Measurement Point by offsetting the support tube end point along the centerline and to the inside of the support tube by the amount calculated in steps 1-3
5. Congratulations, you now have a measurement point that represents the nominal location of the support tube end, taking into account the offset required due to SMR positioning inside the center hole

To take the measurement we used the Build/Inspect mode in PolyWorks.  In this mode we have to be sure to select the "Towards Object" compensation method, which automatically compensates for the radius of the SMR (3/4", or 19.05 mm).  If "None" is selected the FARO measures to the center of the SMR, but our measurement point is at the edge of the SMR, since that's what is physically touching the support tube, so we need to compensate for that radius.  This gives us the deviations of the measurement point, which can then applied to the point representing the center of each support tube end to give their measured location.  The results of our measurements are shown in the attachment.  Since we had measurements for each end of the WBSC3 support tubes I also added a distance feature representing the measured length of each WBSC3 support tube.

Wrapping Up

Some points for discussion/further thought.  Keep in mind that the BSC support tubes are not exact representations of where their respective optics are; we only aligned the optic during aLIGO install, and in the end didn't really care where the support tubes ended up as long as HEPI had enough range to work.  This means that any deviation from nominal seen in the support tube ends is not an indication of misalignment of that chamber's optic.

1. The WBSC2 support tubes were supposed to be lowered by ~2.5 mm to account for the BS z-axis position being at -82.9 mm instead of -80.0 mm; this was done because, while the 4km arm cavities are flat in global coordinates the IFO input and output arms are not, so the BS had to be lowered to properly direct the beam (which rises in elevation while traversing the PRC) into the arms.  Therefore our expectation is that the WBSC2 support tubes are below the nominal z-axis coordinate of 1130.3 mm (we recently discovered that this change was not accounted for in the SolidWorks models for the sites).  While the global z-axis coordinate for all BSC support tubes is 1130.3 mm, if WBSC2 was lowered as required we would still expect to see a z-axis deviation in the measured points, but this is clearly not the case.
   • I was at LLO working on PRC alignment when the WBSC2 in-chamber alignment was started, so I have no memory of the initial positioning of the BS in-chamber; this was done by Hugh Radkins and Doug Cook (I had returned in time for pitch/yaw alignment).  Looking back at their notes they had to move HEPI +X by 4.6 mm, -Y by 2.3 mm, and +Z by 0.4 mm to position the BS, so this does not fully account for apparent lack of support tube lowering.  But as stated above, this does not necessarily mean the BS is too high (we'll know that for sure when we measure it once WBSC2 is opened in March 2026).
2. The measured length for the WBSC3 support tubes is shorter than their as-designed length of 3657.6 mm.  Not sure why at this point.
   • Once we get more full BSC support tube measurements we'll have more info to work from
3. The WBSC3 +X/-Y support tube end is a decent bit further in the +Y axis than expected.  Again, not sure why.
   • Looking back at my notes from install we had to move WBSC3 HEPI in the +Y dircection to properly place ITMx, so the overal deviation direction of these support tubes isn't a surprise.

This work was associated with LHO WP 12947, which also included the WBSC1 +X support tube ends.  Those support tubes still have PEM interface plates installed, so we are currently unable to measure them (will do in the future once the plates are removed).  Since we completed the rest of the measurements involved, I've closed the WP.