Today, Keita and Oli turned up the power to the fiber again so we are getting about 30 mW out. This is enough power that you can see the beam transmit the input coupler of the OMCs easily on a card. With the room lights dim, you can see flashing of the beam at both DCPDs with a card. Using the IR sensitive camera, we are able to fine tune the input alignment further.

The beam has been well-aligned to OMCA, and the flashing present at the DCPDs looks mostly like mode mismatch, which makes sense because we made no effort to mode-match our input beam to the OMCs.

The beam alignment to OMCB still needs some work. It looks predominantly like a yaw misalignment, so we need to make some finer adjustments of the upstream optics.

Since all of the BHSS optics have been pre-angled using the clocking tool, I followed the map on slide 86 of T2100190 to place the lenses, mirrors and beam dumps. Just by eye, I can tell we will need to fine tune this alignment further once we have laser beam. I was unable to place one beam dump because it goes roughly where we are pooling the OMCA cables. Once we can route and clamp those cables properly, there will be room for the dump. I haven't placed the QPDs yet, they are still bagged. I also placed the three head optics randomly, since they can't be placed until the OMC iris template is removed.

As a reminder, the order of operations here is to use the iris alignment template to get good input alignment to both OMCs. Then, this template is removed so we can use other precision templates to align the three optics that go at the head of the manta ray: mirrors A/B-R1 and 36-R1. Then, we can finish the rest of the beam paths to the OMC QPDs.

I took a phone video of OMCA flashing and managed to screengrab these two photos from the videos: DCPDA, DCPDB

I returned to the slider positions where we had good green and IR flashes in the filter cavity from Wed 89629.  Since this time of good flashes the H:M2 pico was reverted to 0 (it's setting during in chamber work), so the green flashes weren't as high as they were on Wed.  Screenshot attached here. In this alignment I went to SQZT7 and looked at the green reflection, it looks like an oval but is coming to the persicope.  (photo)

While at the table, I moved the picomotor for H:M2 X to -710, which is where Tony and I had put it 89596 and where we had both IR and green flashes good.  I could see the beam move on SQZT7, but it wasn't a big move, and after pico'ing it looks like we still have an oval beam making it to the table..  (photo, screenshot)  On the cameras we can clearly see cavity flashes in green but the IR flashes were off the camera, so I went to FCES and centered the flashes on the IR camera (using the seed).  I also went back to sqzt7 and aligned the FC green refl onto the diode.  

While I was there, I watched the green beam on a card while I moved suspensions to see how much freedom we have to move the suspensions and still get the green beam out of the viewport.  I could move ZM1,2,3 and FC1 by a couple hundred urad in both pitch and yaw (although not in either direction), so there is a reasonable adjustment range.  Moving these didn't impact the oblong shape of teh beam, so it doesn't seem like that is caused by clipping.  I then moved the ZM2 psams settings, and saw a big change in beam shape, it became more round looking on a card for strain guages of 4.15 or 5.15 (our usual setting is 3.15).  

I left the alignment back at the one that gave good flashes for IR and green (up to 10, is off in pitch), and with the CLF IR flashes are max 0.15 counts.  

TITLE: 03/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The +/- Y doors were taken off HAM1 this afternoon alog89672, See Jims' alog89673 for the current CS seismic configuration. I'm not sure if the intercom is working, I didn't hear myself after plugging it in and trying the offices. THe LVEA is now is LASER HAZARD, as is the optics lab.
LOG:

• 16:08 UTC HAM3 and BSC2 SUS to safe, their SEI states were already in safe (ISI_DAMPED_HEPI_OFFLINE, and READY / LOCKED) for Fil and Marcs cabling/electronics work
• 16:12 UTC SUS BS wd trip, OSEMs inputs are disconnected it looks like, came back at 21:00 UTC, the pointing still looks the same pretty much the same
• 18:08 UTC SPI laser shuttered in Optics lab
• 18:15 - 18:40 Sophie to CHETA lab
• 22:21 UTC BS ISI ST1,2 WD trip, CPS glitch a minute later

Closes FAMIS39757

Laser Status:
    NPRO output power is 1.83W
    AMP1 output power is 70.39W
    AMP2 output power is 138.8W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 20 days, 23 hr 13 minutes
    Reflected power = 26.87W
    Transmitted power = 104.4W
    PowerSum = 131.3W

FSS:
    It has been locked for 0 days 2 hr and 21 min
    TPD[V] = 0.4974V

ISS:
    The diffracted power is around 3.9%
    Last saturation event was 0 days 2 hours and 25 minutes ago

Possible Issues:
    PMC reflected power is high

Closes FAMIS39341

As expected from the vent and HEPI's being locked on HAMs 1,2,3 and BSC 2,3 the plots look noisier. I don't see any glaring issues with the other chambers.

[Jenne, DaveB, RyanC, Jason, Betsy, Jennie, Keita, Fil, Marc]

Several folks prepping to align optics for HAM1 work noticed at about the same time that several HAM1 and HAM2 suspensions were not behaving as expected.  Eg, I tried misaligning and aligning PR3, but nothing happened (I did this because the sliders hadn't changed, but the OSEM readbacks had changed).  The team prepping to go into chamber similarly noticed that there were no counts going out to the IOP models.

Fil and Marc had a quick look at the sat amps for the HAM2 suspensions (just in case, even though no one had been near them), and everything looked fine.

Upon going back to the control room, I finally noticed on the CDS overview screen that IOPSUSH12 had its DAC Kill light illuminated. After some clicking around, we found the dac kill watchdog screen, and hit RESET.  However, PM1's RMS was still larger than threshold, because HAM1 is at air and the purge air is on, so its undamped motion was too high.  I clicked BYPASS on PM1, which let signal go through to damp PM1.  PM1 quieted down, and I un-bypassed it by hitting RESET again. 

At this point, it seems like all of the suspensions on HAMs 1 and 2 are again behaving as expected.

Rahul, RyanC

Over the past few weeks we've prepped the two basic HXDS assembly (structure sn 035, alog88828 - OMA3 with B2-03 optic, and structure sn 029, alog87998 - OMA2 with A1-03 optic) that we received from LLO. Rahul and Camille assembled these PSAMs at CIT. We attached the wires using the provided HDS Bottom Mass Wire Plate ASSY D2000395 setting the top blade height first using the blade height gauge then feeding the wire down, and the bottom mass (PSAM) with its fixture assembly plate. The wire clamps really wanted to clock when I was doing the final turn, turn and a half on their fasteners so I had to tighten them very slowly. For OMA2 we had some trouble trying to remove the intermediate mass fixture plate D2000230 to replace it with the BOSEM Cam Adj Mtg ASSY as there was a stuck dowel pin. The fixture plate was a V1 version which did not have the emergency release feature that the later version has. We brute forced it out without damaging any components or wires but the intermediate mass shifted a decent amount despite my efforts to keep it still. OMA3 did not have this issue as it was as the V2 plate.

Once we had OMA2 fully assembled, we balanced it then brought it over to the test stand and connected the four OSEMs to the top stage. This first suite of phase 1a measurements was done without the M2 PSAMs cable connected.

The OLV counts were as follows (we later swapped LR and UR, which is reflected below) for OMA2:

UL: 28460 UR: 31900

LL: 29720 LR: 30860

The data/templates live in: /ligo/svncommon/SusSVN/sus/trunk/HXDS/X1/OMA2/SAGM1/Data

and the result pdfs are in: /ligo/svncommon/SusSVN/sus/trunk/HXDS/X1/OMA2/SAGM1/Results

I ran 3 sets of measurements on Wed with a bw of 0.02. The first measurement 2026-03-25_1730 showed some weirdness with LR and lots of cross coupling from Length into Pitch and a bit into Yaw, the shapes were a little different, as well along with the magnitude but that's probably from the coil driver gain. Rahul then swapped the LR and UR OSEMs and double checked the centering, and I ran another measurement 2026-03-25_1900, which looked about the same. Rahul then went and improved the balancing as best he could (the masses were pitching a bit) and I ran a final measurement 2026-03-25_2130.

Overall the Transfer Functions look ok but there's still room for improvement. 

On Thursday Rahul balanced and set up OMA3 on the test stand. Unfortunately while manipulating OMA2 one of the bottom M2 stage wires broke, so we will have to replace it and remeasure it next week.

The OLV counts were as follows for OMA3:

UL: 27030 UR: 32100

LL: 27500 LR: 28900

The data/templates live in: /ligo/svncommon/SusSVN/sus/trunk/HXDS/X1/OMA3/SAGM1/Data

and the result pdfs are in: /ligo/svncommon/SusSVN/sus/trunk/HXDS/X1/OMA3/SAGM1/Results

This set of transfer functions, 2026-03-26_1900 also looks ok and similar to OMA2, see the comparison plot of OMA2 and OMA3. Both measurements shows some weirdness with LR that is not seen in an OSEM noise spectra that we're still looking into.

The next steps are to repair the bottom wire on OMA2, attach PSAMs cables, remeasure then fine tune both OMA2 and OMA3.

Tagging EPO for Corey for the pictures. I'm realizing I only have pictures of OMA3, I might comment with more photos on Monday of OMA2.

(Travis, Randy, Fil, Betsy, Marc, Jim, Gerardo)

Both doors for HAM1 are off, +Y and -Y. 
    - Y Door we had one of the O-rings get stuck to the door, used the tool to set the O-ring back into its groove without a problem.  No further issues.
    + Y door, we took a peek at the O-rings and they looked suspiciously good all over, even with a small gap, but then out of the sudden one of the O-rings jumped out and dropped to the floor.  So, the +Y door has the flange protectors over a single O-ring.

Purge air was turned up.  A photo of the dew point is attached, this as measured this morning by Travis.

A big "thank you" for those that helped with the cleanroom moves.

As of right now, HAM1-2-3 and BSC 2 & 3 HEPI are locked, and after doors came off HAM1 ISI is also locked. HEPIs are all bypassed in the model (by setting ISO master gain to 0). HAM1 should just be left tripped for the work in that chamber, HAM 2 &3 and the BSCs should be left with damping loops engaged, unless there is a need for better alignment to the IFO.

Writing this alog to clarify some mistakes we have made regarding the naming of DCPDs. Jeff clarified to us on call this morning that the naming convention is A- photodiode on reflection, B- photodiode on transmission.

Therefore, here is the now corrected information about which high QE photodiodes are installed where, along with cabling and pin numbers:

OMCA (SN 103)

• DCPD B (TRANS)
  • DCPD: 1D-20
  • Housing: SN 10
  • cathode/anode/case wired to pins 1/2/6 of cable D2300118
• DCPD A (REFL)
  • DCPD: 1C-12
  • Housing: SN 06
  • cathode/anode/case wired to pins 4/5/9 of cable D2300118
• PZT cable D2300120

OMCB (SN 105)

• DCPD B (TRANS)
  • DCPD: 1C-14
  • Housing: SN 002
  • cathode/anode/case wired to pins 4/5/9 of cable D2300119
• DCPD A (REFL)
  • DCPD: 1C-10
  • Housing: SN 008
  • cathode/anode/case wired to pins 1/2/6 of cable D2300119
• PZT cable D2300121

Fri Mar 27 10:10:14 2026 INFO: Fill completed in 10min 10secs

I've added a "degraded state" indicator to the VACSTAT block on the CDS Overview MEDM (magenta oval in attachment). This circle is either the same light green as the block colour, or is a darker green to show at least one gauge has been disabled.

Currently we are running with HAM1 PT100 disabled in VACSTAT due to the vent.

The VACSTAT detailed MEDM (snippet in lower part of attachment) has a "NUM_GAUGES_DISABLED" line added, which turns RED if non-zero.

TITLE: 03/27 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: 4mph Gusts, 1mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.27 μm/s 
QUICK SUMMARY:

• HAM1 doors are coming off today +Y, -Y
  • Later... set tables back up to lock JAC in air and work on REFL and POP paths

Since yesterday, we have received an answer from Ali and Keita, that the determination is that the cathode and anode pins are in the correct location. There is a longer explanation about what's going on here and which diagrams are wrong, but I will leave that to them. Therefore, the only cable work that needs to be done is to adjust the pins on our "bad" cable, and then switch the DCPD cables between OMCA and OMCB.

Morning (no cable work):

Oli and I pulled the first contact that we left from yesterday. We just need one 50/50 45 deg AOI mirror for BHSS, and we were able to completely clean two of this type. More of these mirrors will be needed for the greater BHD layout, so Oli and I need to revisit the other three that still are not clean. For now, they are stored on the flow bench in clean single cases.

We went to begin the BHSS alignment, and found that no laser beam was coming out of the fiber. Some time between this alog, when Camilla and Oli aligned the beam into the fiber, and now, the beam was misaligned again. We think one of the mirrors to the fiber coupler was bumped. Correcting this took a little while. Oli had to leave, so Keita and I continued with the alignment. Luckily, our downstream alignment is still good- with the iris alignment template placed on the BHSS, we can see the beam comes down the center of both irises to OMCA.

Most of the beam reflects off the OMC, so Keita and I started turning up the power into the fiber. At some point, we turned up to 20 mW coming out of the fiber. We could see a faint beam transmit from the input coupler and make it to the output coupler. However, we still had a hard time seeing any beam make it to the DCPDs, probably because the power is still very low. We set up a beam block of the OMC REFL path for now, since it just goes right back off the suspension. At this point, we realized it's probably not a good idea to put so much power into the fiber, so we lowered the power again to have about 2 mW coming out of the fiber.

Afternoon (cable work):

Keita and I proceeded to fix the cables. We first checked which cables went to which pins:

Cable D2300119 (for OMCB): longer is on trans PD, goes to pins 4/5, shorter on refl PD, goes to pins 1/2

On Monday, Randy, Jordan and the FAC team craned the HAM3 cleanroom over into the appropriate place for HAM3 entrance for installation planned next week.  The cleanroom is now up against the BSC2 Platform.  As well, Kim and Nellie have been cleaning the HAM3 cleanroom.

On Tuesday, Randy craned into place and attached the new Installation Platform Sections G and F to the BSC2 platform.  Handrails will be installed next.  These platforms allow access from the eMod cleanroom to the BSC2 cross flow Dome cleanroom and platform, as well as provide added walking space between BSC2 and BSC3.  They also form 2 sides of the BSC3 platform which will be needed in subsequent vents.  Recall, this new LHO BSC2 Installation setup is part of the readiness review for install at https://dcc.ligo.org/E2400329-v1, and is part of a bigger plan to add sections around BSC3 and BSC1 to make a larger platform instead of moving them and encountering interferences other items like racks, trays and equipment.

"It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife"

- Jane Austen, opening line of Pride and Prejudice

But unfortunately for both us and them, sometimes those men are winged termites in the Optics Lab.

As Elenna and I were cleaning up our work in the back optics table this afternoon, we noticed a few winged termites, and ended up finding maybe almost 10 in total walking around on the floor in the back area of the optics lab near the wall mounted cabinets between the two cleanrooms. We got rid of them but couldn't find where they had come from. I'm wondering if they're maybe coming from an opening under one of those cabinets? Last year this happened but those came out from under the flow benches along the wall - not sure if this is part of that same colony that survived or a different colony.

Sheila, Camilla.

We decided to pause on looking for the FC alignment and look at SQZ alignment into the IFO. To check our irises and possibly look for scattering shelves. 

Locked SEED_DITHER with 75mW into fiber. Moved ZM3 to get OPO_IR PD up to max 0.9mW. Opened BeamDiv and after aligning SRM, mis-aligning SR2, could see beams on AS_A,B and C. AS_A and B had a similar size ~60 to reported before (e.g. 86965), but there was less power on AS_C: 4e-4 rather than the previous 7e-4.

We used Ryan's DRMI time from 89573 to put OM1, OM2 and SRM back. The with the SQZ SEED injected, we tried to use SQZ centering loops to center on AS_A and AS_B, this didn't work quite as expected. ZM4 kept saturating although these loops had worked Janaury 19th, before moves were done on the VOPO to help with clipping e.g. 88966.

Then went back to alignment on Jan 31st with 88976 with ZM1,2,3, 4,5,6 FC1. And took OM1,2,SRM to the January 19th positions. However here we saw no light on SQZT7 OPO IR PD, HAM7 WFs or in HAM6 on the AS_A,B,C diodes. This was done at 23:10 UTC. Comparisons of osems attached. The sliders to get these osems values are fairly different, see attached, so I also tried going to these slider values, that gave me some light on SQZT7 IR PD, HAM7 WFS and FCES with SEED injected, see attached. HAM6 AS diodes saw nothing. 

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

Elenna, Oli

Summary: OMCB has its DCPDs installed and most of its stoppers (barring one that needs to be retapped + helicoiled). OMCA has been aligned according to the OMCA / OMCB install template and is ready for laser alignment. Cabling for both OMCs should be good to go.

After last week's issue of the OMCB DCPD A (TRANS) missing a diode hole (89583), we were able to clear up the issue and fix it (89606). Elenna then installed the DCPD B (REFL) diode. Note that once again there were tiny metal shavings below where the DCPD's were installed, which we picked up with a qtip that we wet with iso. Once we had both installed (pic), we installed the rest of the stoppers around OMCB. The only one we didn't install is one of the vertical stops. This is because there was an issue with the helicoil last week, and we ended up having to remove it. We think this might be due to an issue with the threads, so we are waiting on a 3/8"-24 tap to retap the hole before installing a new helicoil. Because we don't have this stop yet, it doesn't really make sense to fasten on the butter dish, but we might just sit it on today to hinder dust accumulation.

We also realized that the PZT cables were going to be way too short to reach the cable pylons for both OMCA and OMCB, so we very carefully opened the peak cable wraps on the OMCs and took out what we think should be enough. On OMCB we noticed that the little copper wrap for one of the PZTs was not right above the PZT as it should be, but instead was on the other side of the peak cable wrap and was only wrapped loosly around one of the cables. Because of this we just removed the wrap. The cables right above the PZT are looking fine and don't look like they need anything to hold them together.

I had been confused about the OMCA / OMCB install template for the past few days, since installing it was putting OMCB further back in its slot than OMCA, but I was able to confirm yesterday in eDrawings that OMCB is actually supposed to be an extra 1 mm away from the front of its slot as compared to OMCA, so we moved OMCA into position and bolted it down.

I also went in and installed the magnet mounts for the OSEM magnets (without the magnets), as well as the big mass on the back of the BHSS.

Installed serial numbers:

OMCB (SN 105)

• DCPD A (TRANS)
  • DCPD: 1C-14
  • Housing: SN 002
• DCPD B (REFL)
  • DCPD: 1C-10
  • Housing: SN 008

Elenna, Keita, Oli

Input alignment:

Today Elenna and I finished fine-tuning the alignment into the BHSS, so now our beams pass through both sets of irises on the alignment tooling plate, so they should be well aligned to go into the OMCs nicely.

OMCA in cradle:

We also opened up what is going to be OMCA (SN 103) and placed it in its cradle. We followed the installation instructions and placed the OMC 1mm away from the three installed horizontal stops, but then we noticed that lining the short end up against the side horizontal stop led to the OMC overhanging the cradle on that side by a few mm. We're not sure if these end stops are also supposed to be further inwards than 1mm (the instructions just specify that they (the horizontal stops) will be touching the OMC 1mm in), but if we placed the other end stop in with the way that the OMC is currently positioned, that other stop would have to screw in at least 3 or 4 mm to meet up with the OMC. We will add photos of this tomorrow.

Installing DCPDs onto OMCA:

Keita and Elenna (who was chained to the optics table via grounding strap) very carefully trimmed the DCPD wires for D1-20 and C1-12 and placed them in the DCPD mounts for DCPD A (which is what we think TRANS is), and DCPD B (which is what we think REFL is), respectively. Faceplate SN 10 was installed onto DCPD A, and faceplate SN 06 was installed onto DCPD B to hold the PDs in place. It was very hard to get the length of the DCPD pins right, and getting the faceplates on and secured. There seems to be a small gap in between the faceplates and the DCPD housing (pic1, pic2), but LLO has the same thing happening so it seems okay. 

Checking pins

After we used a multimeter to check that the case pins followed D220027. According to D220027 the case pins should be going to pins 6 and 9, but we found that they went to what we thought were pins 1 and 4 when we were looking at the prongs. Later we found that the DB9 pin layout is read the other way, so that means that it was actually pins 2 and 5. This still doesn't line up with D220027, but looking at the schematic for the cable D2300119, it turns out that the wires for the Cases for the two DCPDs are shifted so that the Cases do actually go to pin 2 and pin 5, so they're wired correctly! It's just that D220027 is wired up incorrectly and appearantly the cable pins are read with the prongs facing away from you for some reason.

OMCA is looking pretty good so far! (pic3, pic4)

Summary of installed serial numbers:

OMCA (SN 103)

• DCPD A (TRANS)
  • DCPD: 1D-20
  • Housing: SN 10
• DCPD B (REFL)
  • DCPD: 1C-12
  • Housing: SN 06