aLIGO LHO Logbook

H1 IOO - IMC scan for mis-polarization measurement

masayuki.nakano@ligo.org — Sun, 01 Feb 2026 21:37:07 -0800

Author: masayuki.nakano@ligo.org

Report ID: 88984

LIGO git repo: https://git.ligo.org/masayuki.nakano/lho_jac_installation/-/tree/2bd2518c1e08635017066b16d4b7c5f752ed0ea5/

Summary

We performed IMC scans to evaluate mis-polarization and spatial mode content associated with the JAC installation. First, reference measurements were taken before the EOM installation using intentional MC2 yaw/pitch misalignment to robustly identify higher-order modes. After the EOM installation, the same type of IMC scan was repeated. The post-EOM measurement shows that the mis-polarization signature observed before the EOM is strongly reduced, while a significantly larger higher-order mode content is present, indicating substantial mode mismatch in the current post-installation layout.

Procedure

The HAM1 output beam was aligned to the IMC as well as possible using HAM1 mirrors.
The FSS autolocker was stopped, and a laser frequency scan was applied using the laser PZT:
- Triangle ramp: 0.1 Hz, ±8 V.
IMC alignment was slightly optimized using MC2, but not perfectly:
- Some TEM10/01 content was intentionally kept to aid robust peak identification.
Data acquisition:
- Channels recorded:
  - JAC-PZT_DRV_OUT_DQ (frequency proxy)
  - IMC-MC2_TRANS_NSUM_OUT_DQ (IMC transmission)
- Each scan was recorded for 200 s.
Pre-EOM reference scans were taken with three alignment conditions:
- Nominal alignment (reference) GPS: 1453668961
- MC2 pitch returned to the initial (bad-alignment) value: GPS: 1453672393
- Pitch restored, MC2 yaw returned to the initial value: GPS: 1453677200

After the EOM installation, a representative post-EOM scan was taken with the same scan settings. For this measurement, the IMC transmission whitening gain was set to 30 dB. Unfortunately, the GPS start time for the post-EOM dataset was not logged at the time of measurement.

Notes

The IMC is free-swinging during the scan; the JAC PZT signal is used as a proxy for the instantaneous laser frequency.
Intentional yaw/pitch misalignment in the pre-EOM scans enhances TEM10/TEM01 as expected, confirming reliable mode identification and peak labeling.
The IMC scan after the EOM installation exhibits noticeably stronger higher-order mode resonances than the pre-EOM reference scans.
Calculation details can be found in the LIGO Git repo.

Result

In the pre-EOM scans, the p-polarization resonance (π-shifted from s-pol) is visible at the \sim 0.1\% level, indicating a small but measurable mis-polarization component as shown in the second attached plot. The wider peak at the center is the p-pol resonance. The MC mirrors has higher transmissivity for p-pol the finesse for p-pol is lower than s-pol peaks.
After the EOM installation, this p-polarization signature is no longer apparent, indicating that the mis-polarization is strongly reduced. It might be due to the filtering effect of the EOM. The mispolarized component caused by the input periscope is filtered by the EOM birefringence.
In contrast, the post-EOM scan shows a substantially larger higher-order mode content (notably a large 2nd-order component ~10%), indicating significant mode mismatch in the current post-installation layout.
A dedicated mode-matching calculation based on the as-built post-EOM layout will be reported separately in the near future.

IOO

Images attached to this report

LHO VE - Sun CP1 Fill

david.barker@ligo.org — Sun, 01 Feb 2026 10:24:18 -0800

Author: david.barker@ligo.org

Report ID: 88983

Sun Feb 01 10:08:16 2026 INFO: Fill completed in 8min 12secs

Images attached to this report

LHO VE - Sat CP1 Fill

david.barker@ligo.org — Sat, 31 Jan 2026 11:29:53 -0800

Author: david.barker@ligo.org

Report ID: 88982

Sat Jan 31 10:06:56 2026 INFO: Fill completed in 6min 52secs

Images attached to this report

H1 INS - Comment to New Horizontal HEPA Filter Fan Array Installed On BSC2 Elevated Work Platform (for upcoming BBSS installation)

betsy.weaver@ligo.org — Fri, 30 Jan 2026 21:33:54 -0800

Author: betsy.weaver@ligo.org

Report ID: 88981

Note, the HEPA bank wall is intended to be moved from platform to platform when needed, so any interference of other areas due to them is somewhat temporary.

H1 IOO - Measuring EOM mod depth with new EOM

jennifer.wright@ligo.org — Fri, 30 Jan 2026 19:10:24 -0800

Author: jennifer.wright@ligo.org

Report ID: 88979

Jennie W, Jason O, Masayuki N, Keita K, Jim W,

Summary: To check the function of the new EOM in chamber we made a measurement of the modulation indexes by locking the IMC and aligning the beam to AS_C with SR2. We couldn't get a good measurement of the sideband heights but this is probably due to the RF power being down by a factor of 100 from nominal. Will check with EE/Daniel on Monday.

First order of business was checking for stray beams at 100mW input power. Jason moved the BD we already placed for JM2 as we had moced this mirror position yesterday. We also put a new beam dump right after unused JAC port (output side there is tranismission through the curced mirror).

After this we turned the power up to 1W.

Lastly we found a stray beam exiting the table in the -Y direction, this was traced to the JAC REFL path. The REFL beam was hitting the side of a beam dump (near the -X side/PSL of the table) which is meant to cath a beam reflecting off the SEPTUM plate. This beam reflected off the beam dump causing a stray beam. We re-aligned the REFL path so the beam does not do this and instead bounces off the three REFL path steering mirrors and heads into a previously placed beam dump for this purpose on the -Y side of the table. This path will have to be re-aligned in order for the beam to get onto the IOT1 table.

No further stray beams were found so Jason de-energised the waveplate.

Photos to come.

After realising that the beam did not reach the AS_C,A and B QPDs yet we came to the control room to re-align to the output port. This is with the ITMY, PRM and SRM mirrors mis-aligned to allow us to mode scan the OMC in the 'single bounce' IFO configuration.

After Jim re-isolated HAM4,5 and 6 and BSC2 for us we were able to use SR2 to bring back the alignment to AS_C and then turn on the DC centering loops for AS_A and AS_B.

The OMC ASC did not work at first as the suspensions were railed. I cleared the ASC history, this did not help. We cleared the locking filter banks for OM1-3 and this unrailed the outputs and allowed us to turn on the OMC ASC.

We took an OMC scan at 1W input power, shown here. Roughly calibrated into MHz with the known FSR.

We cannot identify the 45MHz or 9MHz peaks, but after checking we realied that these RF driver powers were lowered 15 days ago. See image.

We will come back to this Monday.

Jason put back the rotation stage, locked it out and closed the light pipe.

ISC, PSL

Images attached to this report

H1 PEM - Dust monitor in the optics lab got huge for about 30 minutes

keita.kawabe@ligo.org — Fri, 30 Jan 2026 18:56:07 -0800

Author: keita.kawabe@ligo.org

Report ID: 88980

In the control room, the alarm handler was complaining about opticsd lab dust monitor.

It seems that it surged up and stayed there for about half an hour. I acknowledged the alarm (the dust conts are already back to normal, it seems).

Not sure what happened but this seems to happen kind of regularly.

PEM

Images attached to this report

H1 IOO - Beam Dumps Added and Moved for JAC

jason.oberling@ligo.org — Fri, 30 Jan 2026 18:53:58 -0800

Author: jason.oberling@ligo.org

Report ID: 88978

J. Wright, J. Oberling

As part of WP 13006, we added another beam dump and moved one to ensure all stray beams that we could find were properly dumped.

We added the required beam dump on the unused output port of the JAC, to dump the unused beam here. We also moved the beam dump that catches the leakage beam through JM2 so that it continues to dump this leakage beam in JM2's new location (needed to move JM2 as a result of EOM installation). See the 2 attached pictures.

While scanning for other stray beams, I noticed a beam on the outside of the large beam dump that was temporarily relocated to the +X side of the new JAC input periscope. This was traced to the JAC REFL path. Turns out that when the REFL path was installed, the beam was erroneously reflected off of this beam dump on its way from JACR-M1 to JACR-M2. To fix this we had to loosen the dog clamps for JACR-M1 and physically rotate it until the beam was centered on JACR-M2 (there wasn't enough range in the yaw actuator). We then had to loosen and physically rotate JACR-M2 so that the REFL beam was once again captured in its temporary beam dump (dump located on the -Y side of the ISI). Both mirrors were re-secured to the table. Unfortunately, this means that we will have to revisit REFL path alignment to the new IOT1 table.

Images attached to this report

H1 PSL - PSL Rotation Stage Status (WP 13006)

jason.oberling@ligo.org — Fri, 30 Jan 2026 18:43:05 -0800

Author: jason.oberling@ligo.org

Report ID: 88977

Modulation depth measurement work has been completed for the day, so I have returned the PSL power in HAM1 to 0.1 mW and de-energized and locked out the PSL rotation stage. The PSL shutter has also been closed and locked out for the weekend.

We will need to revisit the modulation depth measurement on Monday, so I am leaving WP 13006 open and extending its date.

OpsInfo

H1 SQZ - HAM7 wrapping up laser work

sheila.dwyer@ligo.org — Fri, 30 Jan 2026 17:58:22 -0800

Author: sheila.dwyer@ligo.org

Report ID: 88976

Today Rahul and I worked on reducing the last bit of clipping in HAM7. The power budget shows a couple of percent more loss than we've expected previously, but I don't think we can improve it much right now so this is good enough. QPDA segment 3 is railed.

This morning we found that we had some loss on B:L2, see Rahul's power budget alog as of lunchtime: 88971. In hindsight, this was also possible in the power budget that Kar Meng reported before the suspension work this week, 88847. We translated the beam in the -Y direction in the SFI2 aperture, so it would make sense that we might need to translate the lens in the -Y direction. However, there is no space to move it because the mount is already as close as it can be to SFI2 (photo). So, we translated the beam using B:M3, using the power meter to judge when we were improving the alignment. We found that this aperture is very small, there isn't much of a plateau where we aren't clipping.

After doing what we could to reduce the yaw clipping here we did a careful power budget with the thorlabs power meter, we seem to have 8% loss to SQZT7, 11-14% loss from output of the OPO to the homodyne, which is a bit worse than past measurements ( 65066):

Opo 0.97-1mw
Input to sfi1 0.97 mW
Output sfi1 0.95 to 0.97 mW
Hitting zm1 0.95 to 0.97 mW
Return from filter cavity after sfi1 0.92 to 0.97 mW
After BL1 0.93 mW
Input to sfi2 0.92-0.94 mW
Output from sfi2 0.91-0.92 mW
After B:L2 0.86-0.91mW
After bm4 0.86-0.90 mW
On the table bottom of the periscope 0.87-0.89 mW
Before the homodyne 0.86 mW
Refl power 24mW

We attempted to move B:M3 in pitch to see if we could reduce clipping on B:L2 that way, but that did not improve the transmission. In pitch we also saw that we increased the clipping with small moves in either direction. I will try to look up the beam size and aperture size next week to see if this makes sense.

We adjusted B:B4 and ZM4 a bit to align onto the two irises on SQZT7.

We also walked the two picomirrors used to center the FC QPDs, with the seed beam which saturates the diode. From the control room I reduced the power and was able to mostly center, but it seems that QPDA segment three has been railed at 33.9 since November 29th.

After we finished up, I went back to check the FCGS alignment onto SQZT7, which was not good, so I went back in for a few minutes to get that beam onto the filter cavity reflection diode. I also had a look at the red + green co-alignment, which looks similar to what Kar Meng posted in 88859.

We also checked that the new cable routing doesn't block the beam onto H:PD1, we couldn't see the beam but we think it looks like a clear path. Rahul also took a photo of where the beam exits SFI2.

Images attached to this report

H1 General - Friday Ops report

anthony.sanchez@ligo.org — Fri, 30 Jan 2026 16:31:40 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88975

TITLE: 01/31 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
JAC team seems to have made some progress today... the MC was locked in air today.
SQZ Team went to align the beams in HAM7.

Rotation stage is de-energised, Lightpipe is currently open. The JAC team are hoping to get some tests done before EOD, and the LightPipe will be closed before they leave.

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
22:49	SAF	LVEA IS LASER HAZARD	LVEA	YES	LVEA IS LASER HAZARD \u0d26\u0d4d\u0d26\u0d3f(\u239a_\u239a)	16:49
15:41	FAC	Nellie	LVEA	N	Technical Cleaning	17:20
15:50	FAC	Christina	MEch room	n	Unloading paper products into Mech room	16:20
17:01	Saftey	McCarthy & Randy	LVEA	N	Looking at HAM1 & HAM7 work	17:10
17:25	JAC	Jason , Masasuki	LVEA HAM1	Y	In chamber work on HAM1	19:34
17:28	SQZ	Rahul & Sheila	LVEA HAM7	yes	SQZr Laser path alignment work	20:01
17:44	JAC	Keita	Optics Lab	n	Looking for parts.	18:14
17:48	FAC	Corey & Randy	LVEA	yes	Craning from Highbay to Biergarden.	19:00
19:19	SPI	Jeff	Optics lab	yes	SPI colimation!	20:42
19:50	Cheta	Jason & Jennie W	Cheta LAB	yes	CHETA work	19:55
20:32	FAC	Randy	LVEA	y	BSC2 work	21:46
20:46	VAC	Gerardo	LVEA HAM1	y	Turning down the purge air.	21:05
21:11	SPI	Jeff	Optics Lab	y	SPI collimation	22:38
21:13	JAC	Jennie W & Jason	LVEA HAM1	y	Beam Measurements	21:20
21:29	SQZ	Rahul & Sheila	LVEA HAM1	y	SQZ beam alignment. Rahul out first.	00:29
21:30	EE	Marc & Yuri	MY	N	dropping off parts.	21:51
21:46	VAC	Gerardo	LVEA HAM1	y	Turning up purge air	21:50
21:51	JAC	Jason Jennie W & Masiuki	LVEA HAM1	yes	placing beam dumps on HAM1	23:46

H1 IOO - First IMC lock with new EOM

masayuki.nakano@ligo.org — Fri, 30 Jan 2026 15:45:33 -0800

Author: masayuki.nakano@ligo.org

Report ID: 88974

[Keita, Jason, Masayuki]

Summary

The beam alignment inside HAM1 was carried out using JM2 and JM3 after the EOM installation. Alignment was optimized by observing higher-order modes (HOM) and maximizing TRANS peak power. After verifying the presence of a PDH error signal at IOT2, the demodulation phase was adjusted since the new EOM will change the modulation phase due to the location difference. The IMC was then successfully locked using the common mode servo, following the Guardian sequence manually. The tuned IMC-REFL_A_PHASE was 20.87°

Detailed Procedure

Beam alignment inside HAM1 was performed using JM2 (scratched) after EOM installation. The beam was aligned to an iris placed between JM2 and JM3 using JM2’s mirror position and angle. The beam position matched the iris within approximately ±1 mm.
Further alignment between JM2 and JM3 was done using the iris after the periscope. A beam walking procedure was used: JM2 aligned the first iris and JM3 aligned the second.
After this, the Septum window cover was removed. The beam reached the IOT2 table, but there was a yaw offset. JM2 was further adjusted to correct it (note: yaw in HAM1 corresponds directly to yaw on the IOT2 table).
A small sweep of JM2 in pitch and yaw revealed a very weak resonance peak. To excite the cavity, a 0.1 Hz, 300 cnts signal was sent to the TEST filter of MC2 M1.
The TRANS camera showed the presence of a higher-order mode (HOM) with a pitch misalignment. Beam walking was repeated: small adjustments to JM3, followed by peak maximization with JM2. After several iterations, yaw HOM became dominant, so the axis was adjusted accordingly. A final pitch correction increased the TRANS power to approximately 6 cnts, concluding the alignment.
Returning to the control room, the IOT2 shutter was opened. A PDH error signal was observed, confirming that modulation was present. Since the signal appeared primarily in the Q-phase, the demodulation phase was rotated by 45° using a delay line circuit.
The common mode servo gain was set to 14 dB. When the input switch was engaged, the system began to catch resonance. By enabling the Lock filter on MC2 M3, the cavity successfully locked. The Lock filter for MC2 M2 was then engaged with gain 0.1, and FM3 was turned on, allowing stable long-term lock. These steps followed the Guardian sequence.
A 50 Hz, 400 cnts excitation signal was injected into the IMC_L filter, and the delay line phase was tuned to minimize the RF25_Q_ERR peak. The optimal demodulation phase (IMC-REFL_A_PHASE) was determined to be 20.87°.

IOO

LHO FMCS - Using Vibration Sensors To Gauge Health Of HVAC Fans Site

anthony.sanchez@ligo.org — Fri, 30 Jan 2026 14:48:15 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88973

Using Vibration Sensors To Gauge Health Of HVAC Fans Site Famis 27735
No big changes here, got a few spikes that are likely DAQ restarts.

Images attached to this report

H1 TCS - TCS Monthly Trends

anthony.sanchez@ligo.org — Fri, 30 Jan 2026 14:09:37 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88970

TCS Monthly Trends Famis 38836
There are some large spikes in this data on days where we have someDAQ restarts.

Images attached to this report

H1 INS - New Horizontal HEPA Filter Fan Array Installed On BSC2 Elevated Work Platform (for upcoming BBSS installation)

corey.gray@ligo.org — Fri, 30 Jan 2026 13:56:11 -0800

Author: corey.gray@ligo.org

Report ID: 88972

(Randy Thompson, Corey Gray)

In preparation for the upcoming Bigger BeamSplitter Suspension (BBSS) Installation at BSC2 in a few weeks (~midMarch), a new type of cleanroom infrastructure was needed too allow for more vertical space for the cartridge to be craned in/out of BSC2. Instead of using our standard large mobile cleanroom (which are used for HAM & BSC chamber work), a smaller clean space will be attached to the elevated work platform for BSC2. There will be a "cleanroom tent" on this platform (here's the platform [white] with 2-sets of 4 "tent poles") and a new array of (qty-4) HEPA Filters Fans (same type as the ones on top of the large mobile cleanrooms which blow down) will be on the side of this cleanroom tent to push air flow horizontally for this elevated workspace for the BBSS install.

Randy designed a unistrut framework for this 4-HEPA fan Array (weighs 377lbs). This morning this assembly was carefully craned into place on top of 3 unistrut brackets attached to the BSC work platform (in between BSC1 & BSC2). For added support, this afternoon, Randy added a "leg support" on both ends of this HEPA Filter Fan Array (here is a photo of one of these legs that is in the Beer Garden).

EPO, FMP, INS

Images attached to this report

H1 SQZ - Comment to HAM7 work today

rahul.kumar@ligo.org — Fri, 30 Jan 2026 12:53:20 -0800

Author: rahul.kumar@ligo.org

Report ID: 88971

Power measured this morning in HAM7,

0.95mW out of OPO

0.92mW out of SFI2

0.83mW ou of B L2

0.83mW on table (and looks centered on both the iris on the able).

We are somehow clipping on the lens (placed after the SFI2), we might move it mechanically since adjusting the beam using mirror is not helping.

SQZ

LHO VE - Fri CP1 Fill

david.barker@ligo.org — Fri, 30 Jan 2026 10:18:51 -0800

Author: david.barker@ligo.org

Report ID: 88969

Fri Jan 30 10:07:58 2026 INFO: Fill completed in 7min 54secs

Images attached to this report

H1 General - Friday Ops

anthony.sanchez@ligo.org — Fri, 30 Jan 2026 08:00:51 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88967

TITLE: 01/30 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 3mph Gusts, 1mph 3min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.40 μm/s
QUICK SUMMARY:
LVEA is LASER HAZARD with HAM1 & HAM7 still open for in chamber work.

Potential HAM7 work:
Tweak Alignment from cable Rubbing, OBO & TF

Potential HAM1 work:
Align Path out
IOT2L Beam profile measurement at 100 mW
Replace JM1/JM3 fixed mirrors with HTTS
Lock MC with HAM1 in air
Bifricate LVEA HAM1/South Bay/Work at Height all Laser Haz, rest of LVEA Laser Safe

H1 ISC - Comment to JAC EOM Thursday (Jennie, Elenna, Jason, Masayuki, Betsy, Keita)

corey.gray@ligo.org — Fri, 30 Jan 2026 07:58:42 -0800

Author: corey.gray@ligo.org

Report ID: 88968

EPO Tagged.

EPO

H1 SQZ - HAM7 work today

sheila.dwyer@ligo.org — Thu, 29 Jan 2026 21:39:22 -0800

Author: sheila.dwyer@ligo.org

Report ID: 88966

This morning Rahul took a transfer function of the OPO suspension and found that adding a zip tie to the new connector didn't help the transfer function, which is still similar to 88921. We decided with Jeff to live with this as it is, and we spent the rest of the day working on resolving the clipping through the VIP introduced by alignment shifts that happened as we were addressing the cables.

We moved A:M3 enough that we no longer see evidence of clipping in the SFI1 both passes, we measure 0.96mW out of the OPO and about the same power in transmission from SFI1 on the the return from the filter cavity. We then saw that the beam was clipping in SFI2, and adjusted B:M1 until we were measuring about 0.88- 0.9mW after SFI2, but we had clipping on the aperture attached to B:L2. We had nearly lost the beam to SQZT7 by this time, so we spent some time restoring that by adjusting pitch on B:M3 and yaw on B:M4 (with the platform unlocked it is difficult to adjust pitch on the tough pitch knob for B:M4). This brought us to a point where we can see 0.7 counts on the OPO IR PD on SQZT7.

At the end of the day, we were still seeing loss at B:L2, where the beam was only about 0.82mW. We also need to restore the alignment onto the irises on SQZT7.

We will need to readjust the alignment onto the filter cavity QPDs before we close the chamber.

H1 ISC - Comment to JAC EOM Thursday (Jennie, Elenna, Jason, Masayuki, Betsy, Keita)

keita.kawabe@ligo.org — Thu, 29 Jan 2026 21:04:33 -0800

Author: keita.kawabe@ligo.org

Report ID: 88964

EOM tuning results

It's worth noting that we haven't done any tuning after EOM was transported from the lab to HAM1. Frequencies changed a bit but nothing to worry about.

Below is a table of the dip frequencies and S11 coefficients when the EOM was placed in its final location. They aren't bad, 9 and 45 are as good as anybody can do.

(We also measured them when EOM was placed at the edge of the table, there were measurable differences but nothing disastrous.)

nominal / measured center frequency [MHz]	measured S11 coeff [dB] at nominal / center frequency
9.100230 / 9.1015282	-21.96 / -22.29
24.078360 / 24.074976	-25.84 / -26.74
45.501139 / 45.499614	-23.19 / -23.15
118.30299 / 118.294670	-25.29 / -26.0

Connection

FieldFox network analyzer was connected to the modulation patch panel at the bottom of PSL rack (which is kind of hard to find, see the first picture). Back of that panel is connected to the in-air cable that runs all the way to the vacuum feedthrough on HAM1.

By connecting 50 Ohm terminator to each in-vac cable, we confirmed from FieldFox that ISC_RF5-B1, B2, B3 and B4 correspond to 9, 45, 118 and 24MHz as specified in D1900511-v12 page 43 and 24.

Before connecting the cables to the EOM, we performed S11 calibration by connecting a short plug, 50 Ohm plug and nothing to the SMA connector of in-vac cables via class B SMA elbow.

After the EOM was relocated to its final location, RF sources were connected to the front of the patch panel.

RF levels of the signals directly coming from the 118MHz and 24MHz RF patch panel were: 10.76dBm for 118MHz, 14.2dBm for 24MHz according to FieldFox.

45MHz and 9MHz come from the EOM driver and I didn't bother to measure the power.

Other things

In three_persons_untangling.jpg, Jennie, Jason and Elena (left to right) are untangling JAC EOM cables together.

Images attached to this report

H1 ISC - Comment to JAC EOM Thursday (Jennie, Elenna, Jason, Masayuki, Betsy, Keita)

elenna.capote@ligo.org — Thu, 29 Jan 2026 17:07:45 -0800

Author: elenna.capote@ligo.org

Report ID: 88965

About the cable strain relief posts:

The four SMA cables were connected to the SMA elbow connectors on the EOM. The strain relief posts appear to be designed such that each cable is sandwiched between the two viton pieces, with one screw above and one screw below. I was a bit confused about how exactly to use the screws with hex nuts attached. I instead used the third bottom screw to loosen to slide the cable in, and then tighten. It was helpful to have someone else pinch the viton at the top while I tightened the screw. This is how it looks.

The two cables on the right hand side of the EOM mount feed straight through the strain relief into the SMA connection, this is fine. However, the placement of the post on the left hand side is a bit short of where the SMA connections are, so the cable bends a bit to make it through the strain relief post and go to the connector. This is tricky because the SMA cable is also very stiff. I don't know if this is a problem. I took several pictures of how this looks just in case. You can see how one side is straight and the other side is "S" shaped through here.

There are two more angled shots of the EOM in its place on the table.

About EOM placement:

Jason and I lifted and placed the EOM carefully together while Jennie held the cables. We roughly dog-clamped the cables to the table for now. Jason fine-tuned the EOM alignment by lining up the mechanical mount to holes on the table.

Overall, not bad for placement. We opened the light pipe after placement, locked the JAC and saw the beam go in to the EOM and then come out of the EOM on the other side!

To confirm, we used the thorlabs power meter to check. We measured about 82-84 mW before the EOM, and then 79-80 mW coming out of the EOM.

Further alignment work:

We proceeded to try to realign the beam from JM2 to JM3, given the significant deflection of the beam due to the EOM crystal. There are two irises between the mirrors to guide the alignment. Jason found it very tricky to align the beam to both. During the process, JM2 was knocked over and now has some scratching and cracks near the edge of the mirror. It is fine to use it for alignment now, but the mirror will need to be replaced. The team is working on finding a spare now.

Images attached to this report

H1 ISC - JAC EOM Thursday (Jennie, Elenna, Jason, Masayuki, Betsy, Keita)

keita.kawabe@ligo.org — Thu, 29 Jan 2026 16:55:23 -0800

Author: keita.kawabe@ligo.org

Report ID: 88963

EOM was put in chamber and moved to its final location. One temporary iris, a cable bracket for the picomotors and one dog clamp for the last lens for JAC needed to be relocated as they interfered with the EOM pivot base.
In-vac cables were identified and were connected to the EOM. Minor annoyance about the cable strain relief.
EOM S11 coefficients were measured and were acceptable though the dip frequencies were not the same as in the lab, so we haven't retuned it.
EOM was connected to the RF sources (now we're modulating!).
The light goes into and comes out of the EOM.
We forgot that the EOM wedge has a big effect to deflect the beam. We started working on the alignment downstream of the EOM and this will continue tomorrow.

Details to follow.

EPO, INS, ISC

H1 General - Ops Day Shift End

oli.patane@ligo.org — Thu, 29 Jan 2026 16:32:20 -0800

Author: oli.patane@ligo.org

Report ID: 88962

TITLE: 01/30 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: EOM is in!! Still some work to be done for HAM1 and HAM7. LVEA IS LASER HAZARD
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
15:44		Corey	LVEA	YES	Running HAM1 cable brackets out	15:52
16:18	FAC	Kim, Nellie	LVEA	YES	Tech clean (Nellie out 16:30)	17:48
16:22	FAC	Randy	LVEA	YES	Measuring on BSC2 platform	16:52
16:29	FAC	Nelllie	EY, MY	n	Tech clean	17:39
17:28	JAC	Keita	OptLab/LVEA	n	EOM work	19:35
17:31	SQZ	Rahul, Sheila	LVEA	YES	HAM7 alignment	19:59
17:34	FAC	Randy	LVEA	YES	BSC2 platform work	19:37
17:38	VAC	Jordan	MY	n	Looking for parts	17:56
17:51	JAC	Betsy, RyanS	LVEA	YES	Moving IOT1 away from chamber (RyanS out 19:35)	19:43
17:57	SPI	Jim	OptLab	n	SPI work	19:11
18:01	EE	Fil, Marc	LVEA	YES	Pulling cables	19:14
18:03	JAC	Elenna	OptLab/LVEA	n	EOM work	19:35
18:04	FAC	Kim	LVEA	YES	Tech clean	18:24
18:10	JAC	Masayuki	LVEA	YES	EOM	19:35
20:30	FAC	Randy	LVEA	YES	BSC2 platform work	22:49
20:43	EE	Fil	LVEA	YES	Cabling for BHD	21:56
20:43	JAC	Keita	LVEA	YES	EOM installation work	20:58
20:49	JAC/VAC	Jason, Jennie, Jordan, Keita	LVEA	YES	Replacing septum cover (Jordan out 21:13)	ongoing
21:02	EE	Marc	LVEA	YES	Helping with JAC	21:21
21:10	JAC	Elenna	LVEA	YES	JAC	ongoing
21:26	SQZ	Sheila, Rahul	LVEA	YES	HAM7 aligning	00:01
22:25	EE	Marc, Yuri	LVEA	YES	Looking around	23:25
22:39	BHD	Betsy, Jenne	OptLab	n	BHD things	23:54
23:19	JAC	Masayuki	LVEA	YES	JAC work	ongoing
23:27		Richard	LVEA	YES	Checking in on everything and being nice to people	22:57
00:21	FIT	Matt	YARM	n	Running	ongoing

H1 PSL - Comment to Input power to HAM1 at 1W

jennifer.wright@ligo.org — Thu, 29 Jan 2026 11:57:27 -0800

Author: jennifer.wright@ligo.org

Report ID: 88960

Pictures of the beam dump positions are attached.

BD one: BD for beam reflected towards PSL from JAC (-x direction).

BD two: beam transmitted through temporary JM3, BD (right one in photo) at edge of table nest to JM1 tip-tilt (in its temporary position in bottom right of photo).

BD three: BD in bottom of picture added for beam transmitted through temporary JM1.

Photo of both BD 1 and 3 zoomed out.

BD four: BD on -x side of table (towards HAM2) catching beam transmitted through JM2, shown in mid-left of photo.

Images attached to this report

H1 AOS - Comment to Wed. Jan/28: JAC EOM is ready to be transported to the chamber (Elenna, Keita)

elenna.capote@ligo.org — Thu, 29 Jan 2026 11:55:40 -0800

Author: elenna.capote@ligo.org

Report ID: 88961

Just want to add some notes:

once the EOM was mounted on the base plate, we used a multimeter to check the isolation of the EOM assembly and the base plate. There was no continuity between the sides, face plate, and bottom of the EOM and the base plate
the strain relief posts required different amounts and types of washers to ensure that when the posts were screwed down they faced the correct direction according to the drawing. You can see this in the third image in Keita's original alog. The left side strain relief post uses one 0.025" washer and eight 0.002" washers. The right side post uses one of the given slotted washers and one thick washer, I can't remember the size (but not one of the already-mentioned washers). Figuring out which washer combination was correct was a very annoying process.
For tuning: this is a very tricky process because the trim pots are very sensitive. To make this extra hard, it's important to note that just bringing the yellow tool in to connect to the washer changes the capacitance significantly, and removing the tool and your hand changes it back. This means that you have to over/undershoot the tuning while your tool is in, and then check to see if you have it right by removing the tool. This requires a lot of trial and error to determine exactly how much overshoot is required. I'll admit that I got it mostly through guessing and luck. I don't see how it would be possible to do this tuning without being right next to the EOM, so in-chamber adjustments are going to be incredibly difficult.

LHO VE - Thu CP1 Fill

david.barker@ligo.org — Thu, 29 Jan 2026 10:21:54 -0800

Author: david.barker@ligo.org

Report ID: 88959

Thu Jan 29 10:07:23 2026 INFO: Fill completed in 7min 20secs

Images attached to this report

LHO FMCS - HVAC Fan Vibrometers Check FAMIS

oli.patane@ligo.org — Thu, 29 Jan 2026 09:12:00 -0800

Author: oli.patane@ligo.org

Report ID: 88958

Closes FAMIS#39852, last checked 88845

Corner Station Fans (attachment1)
- MR FAN1_170 has been relatively loud since it was turned on on Tuesday.
- All other fans are looking normal and within range.

Outbuilding Fans (attachment2)
- MY FAN1_270_1 is quite noisy, but since it's at the midstation I think that's okay
- All other fans are looking normal and are within range.

PEM

Images attached to this report

H1 SUS - HAM7 OPO cable dressing (round 2) - Yaw shows no further improvement

rahul.kumar@ligo.org — Thu, 29 Jan 2026 09:07:42 -0800

Author: rahul.kumar@ligo.org

Report ID: 88957

Sheila, Jeff, Rahul

Yesterday afternoon we moved around two more cables on the OPO (see picture attached for reference). For the first cable (marked by circle) we lifted the cable connector from the OPO and attached it to the nearby pillar using a PEEK tie. For the second cable (marked by arrows in my picture) I provided more relief to it.

This morning I took transfer function measurements for Y dof (0.02Hz bw and 5 averages, with Yaw dof. un-damped and other dof. being damped during the measurement) - see screenshot attached below. I don't see any improvement (in frequencies splitting) - red trace is the latest measurement and blue is the previous one taken by Jeff two days ago.

SUS

Images attached to this report

H1 SQZ - OPO suspension cabling and clipping in HAM7

sheila.dwyer@ligo.org — Thu, 29 Jan 2026 08:49:20 -0800

Author: sheila.dwyer@ligo.org

Report ID: 88956

Yesterday Rahul and I went to HAM7 and adjusted A:M3 in the negative pitch direction to relive the saturation of ZM1 noted in 88939. This was partially sucsesful, after the shift the beam was no longer clipping on the SQZT7 periscope without offsets on ZM1, but it was a little low in pitch on the first iris and the power on the OPO IR trans PD was 0.4 rather than 0.6 counts. With the power meter we can see that there is still clipping between the input to SFI1 and the return beam from the filter cavity out of SFI1.

Rahul adjusted the cables a bit, adding more slack to the one for the OPO temperature controler (before photo shows this as the lighter colored cable with the S routing on the nearby pillar). The beam was still After that the PSL FSS would not lock, preventing us from dither locking the OPO.

Rahul moved the connector for the new translation stage from the lid of the OPO and zip tied it to the pillar on the rear blade spring.

Oli and Jeff are looking at suspension transfer functions right now. I was able to improve the power on the PD from the control room by pitching ZM1 + 400 urad and yawing +500 urad, but there is still not as much light as we expect on SQZT7 IR PD, so we will have to continue this in laser hazard today.

H1 AOS - Comment to Wed. Jan/28: JAC EOM is ready to be transported to the chamber (Elenna, Keita)

corey.gray@ligo.org — Thu, 29 Jan 2026 08:37:58 -0800

Author: corey.gray@ligo.org

Report ID: 88955

EPO tagged.

EPO

H1 AOS - Comment to Wed. Jan/28: JAC EOM is ready to be transported to the chamber (Elenna, Keita)

keita.kawabe@ligo.org — Thu, 29 Jan 2026 08:36:15 -0800

Author: keita.kawabe@ligo.org

Report ID: 88954

We modernized the measurement apparatus and used FieldFox (Agilent/Keysight's handheld network analyzer) instead of 4396B. This was really convenient and helpful because one person could hold the analyzer at a convenient position/angle for the other who was turning the trim cap.

Also it has a splitter and a directional coupler built in so there's no need to connect any such external devices, it's just the analyzer, a cable and the EOM. (But of course you still have to calibrate with short/open/load like in 4396B, see alog 88887.

H1 General - Ops Day Shift Start

oli.patane@ligo.org — Thu, 29 Jan 2026 07:34:37 -0800

Author: oli.patane@ligo.org

Report ID: 88953

TITLE: 01/29 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 4mph Gusts, 3mph 3min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.58 μm/s
QUICK SUMMARY:

HAM1 and HAM7 work continuing today

H1 AOS - Wed. Jan/28: JAC EOM is ready to be transported to the chamber (Elenna, Keita)

keita.kawabe@ligo.org — Wed, 28 Jan 2026 21:24:23 -0800

Author: keita.kawabe@ligo.org

Report ID: 88952

We've assembled the whole EOM assembly including the pivot base/plate assy and the strain relief post and confirmed that the EOM face/side/bottom plates are isolated from the pivot base/plate.

We've tuned the EOM such that S11 parameter at the modulation frequencies are all within 1dB of the bottom of the dip.

We still saw that the frequency shifted for 118 and 45MHz when we tapped the EOM body around, even though there was no appreciable change in 24 and 9MHz. Each jump was small, like 5kHz or 10kHz or nothing sometimes, but they jumped. Surprisingly, at least for 118MHz peak, after the frequency jumped in one direction due to my tapping on the side plate (e.g. the input side), I tapped the other side plate (e.g. the output side plate) and the frequency jumped back into the opposite direction. This was very consistent.

This means that my expectation was wrong. An expectation that somehow something (like coil wires) is caught by something else (like the core by the friction), and that tapping things will release these "something"s into lower potential state and that eventually they all settle.

Realizing this, we stopped tapping, we just tuned as good as we could and stopped.

Tools and parts were wrapped and bagged. EOM assy was wrapped in a foil. These things will be transported to HAM1 tomorrow.

In the first two attachment, Elenna is tuning the trickiest frequency (118MHz).

Following pictures show the fully assembled unit from the back (+Y), input (-X), output (+X) and front (-Y). In front.jpg, note that I'm only using one washer for the low profile 10-32 socket head cap screw. I used to use two, but the screw still stuck out just enough to make things tedious and inconvenient when lowering the pivot plate over the pivot base. Though the screw is 0.5" long and not the initially specified 10-32 x 0.375", with one washer it seems to work.

Next, look at one 1/4-20 screw below the above mentioned 10-32 in caution.jpg. When tightening/loosening that screw, don't use a T-handle wrench unless it's a ball end tool, because you WILL damage the SMA connector thread. Even if you use an L-shaped tool, if you don't pay attention you can damage it. Be careful.

Last picture showcases a happy mood in the optics lab after the successful day.

Images attached to this report

H1 PSL - Comment to Input power to HAM1 at 1W

jason.oberling@ligo.org — Wed, 28 Jan 2026 17:13:55 -0800

Author: jason.oberling@ligo.org

Report ID: 88951

PSL power into HAM1 has been returned to ~100mW and the PSL rotation stage is de-energized and locked out once again.

H1 SQZ - Removed a few parts from HAM7

anthony.sanchez@ligo.org — Wed, 28 Jan 2026 16:55:26 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88878

Friday Jan 23rd Sheila, Karmeng, & myself removed 3 Irises, and swapped out a PD for a beam dump.
First Karmeng & I Turnt up the purge air & took pictures of the table.
Then we found all the irises Sheila wanted to remove:
Iris 1.... which was one of the 3 Sheila wanted to remove along with Iris 2 and Iris3 near by.

We decided to swap a Photodiode for a Beam Dump due to the scattered light documented in this here FRS ticket, as putting a beam dump infront of the PD was not possible due to Space constraints.
Swapping this PD out required some expert level HAM7 Yoga so Shelia did the switcheroo.

I'm sure it will be fine, but the PD was in place to catch light that is there when the IFO is locked.... and well since the IFO wasn't locked... we Eyeballed the placement of that beam dump that took it's place. So we are fairly sure the Beam Dump is in the right place. Oh! I took a few before pics of the PD too just to do some comparing with the after pics of the Beam Dump.
We did check all the beam paths in HAM 7, but that last beam dump we can't check so ¯\_(ツ)_/¯ Looked good to us.

Thanks to Jordan for the last minute purge air cram session.

Later!

EPO

Images attached to this report

H1 General - Ops Day Shift End

oli.patane@ligo.org — Wed, 28 Jan 2026 16:30:12 -0800

Author: oli.patane@ligo.org

Report ID: 88950

TITLE: 01/29 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The LVEA is LASER HAZARD. Lots of HAM1 and HAM7 work today
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
15:36	FAC	Randy	LVEA	YES	Taking down cable tray struts using crane	19:23
16:06	FAC	Nellie, Kim	LVEA	YES	Tech clean	17:12
17:07	TCS	Matt, Sophie	JOAT Lab	n	Installing parts	18:13
17:29	EE	Daniel	LVEA	YES	Testing cabling work from yesterday by HAM6	18:42
17:40	FAC	Kim, Nellie	LVEA	YES	Tech clean	18:13
17:42	JAC	Jennie	LVEA	YES	Catching strays (beams)	18:55
17:46	JAC	Jason	LVEA	YES	Helping Jennie, moving rotation stage	20:01
18:13	FAC	Kim	EX	n	Tech clean	19:43
18:36		Richard	LVEA	YES	Checking in on Randy	18:49
18:47	JAC	Keita	OptLab	n	EOM work	20:56
18:51	PCAL	Tony, Dripta	EX	n	PCAL work	20:12
19:07	JAC	Elenna	OptLab	n	EOM work	20:56
19:23	JAC	Jennie	LVEA	YES	Catching more strays (beams)	20:01
20:38	SPI	Jim	OptLab	n	Working on SPI	21:36
21:46	FAC	Randy	LVEA	YES	Walkaround	22:33
21:51	JAC	Jennie, Jason	JOAT Lab	n	Popping in quickly	22:09
22:08	SQZ/SUS	Sheila, Rahul	LVEA	Y	HAM7 work, OPO (Sheila out 23:03)	23:16
22:14	JAC	Jason, Masayuki	LVEA	YES	JAC work	ongoing
22:17	JAC	Betsy, RyanS	LVEA	YES	Dumping beams and moving tables	ongoing
22:22	JAC	Keita	OptLab	n	EOM work	ongoing
22:41	JAC	Elenna	OptLab	n	EOM work	ongoing
23:05		RyanC, Rahul	LVEA	YES	Moving in table	23:35
23:43	CDS	Dave	EX	n	Turning EX HWS computer back on	ongoing

H1 CAL - PCAL TX Module Maintenance.

anthony.sanchez@ligo.org — Wed, 28 Jan 2026 16:16:23 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88949

Yesterday Dripta & I went to the End X Station to do a TX module Maintenance.
The results of this TX Module Maint can be found here T1600436 :

Laser SN01	Incoming laser power from T1300100
Date	6/4/2013	Aug. 3, 2018	Mar. 19, 2019	Jan-18-2024	April-22-2025	Jan-27-2026
Laser Shutter Check		PASS	PASS	Pass	Pass	Pass
Max OFS Offset		9.9 V	7.8 V	7.7V	7.7V	7.75
95% OFS Offset		9.405 V	7.4 V	7.3V	7.315	7.36
Operating OFS Offset		4.7025 V	3.7 V	3.85V	3.6575	3.68
Laser Output Power	2.05 W	1.72 W	1.75 W	1.67W	1.7	1.662
After-Laser Rejected Power		56.5 mW	54 mW	36.6mW	34.6mW	35.7mW
AOM Input Power		1.60 W	1.69 W	1.59W	1.65	1.64
Max Diffracted Power		0.967 W	1.13 W	1.1W	1.14	1.1
Un-Diffracted Power		0.359 W	0.306 W	266mW	0.307W	0.297
AOM Diffraction Efficiency		60.44%	67%	69.00%	0.690909090909091	0.670731707317073
After-AOM Rejected Power		12.8 mW	13.7 mW	14.7mW	15.2mW	16.7mW
TxPD Power		11.1 mW	6.06 mW	6.36mW	11.9mW	6.14mW
OFSPD Power		5.7 mW	6.56 mW	6.36mW	5.7mW	6.58mW
Outer Beam Power		228 mW	0.257 W	265mW	0.536	512
Inner Beam Power		228 mW	0.255 W	260mW	0.526	501
Output Beam Power Ratio		1	0.992217898832685	0.9811	0.98134328358209	0.978515625
OFS Gain		38.19 dB	41 dB	39.6db	39.6	39.79
OFS Phase Margin		60.9 degrees	55 degrees	43deg	42.1	42.3
ALOG				75484		88949

Images attached to this report

Non-image files attached to this report

PCalTxModuleMaintenanceLog-June2025.xlsx

H1 PSL - Input power to HAM1 at 1W

jennifer.wright@ligo.org — Wed, 28 Jan 2026 13:04:04 -0800

Author: jennifer.wright@ligo.org

Report ID: 88948

Jennie W, Jason O

Jason and I added four beam dumps - two before we turned the power up, two after.

There were no beams leaving the table at 100mW but we dumped two beams going towards the PSL septum plate (one was transmission through JM1).

Jason saw one leaving the table after we were at one watt so this and the transmission throuhg JM3 + JM2 are now dumped.

OpsInfo

H1 TCS - CHETA Update

sophie.muusse@ligo.org — Wed, 28 Jan 2026 12:04:06 -0800

Author: sophie.muusse@ligo.org

Report ID: 88946

S. Muusse, M. Todd

Lens realigned on X-arm CHETA table for corrected focal lengths and the beam profiled which had better agreement with the model. ITM beam size from fit are much closer to ideal beamsize on ITM (≈ 52.7mm).

Model was updated to use measured L1 focal length replacing manufactorer spec which was given for 588nm.
Lens were repositioned based on the updated model
Beam was profiled after L2 and used to fit q-parameters (attached). This was completed using a non-linear fit where M2 was fixed to 1
Modelled beam parameters are just outside of the uncertainty bounds on the fit. We are suspicious of higher order mode contibutions effecting our fit especially in the vertical axis.
Beam profiler is being shipped to LLO

Fit for profile after L2 vs model

	Fit	Model
w_0x,w_0y [um]	[970.5 ± 28.7, 940.8 ± 23.3]	[1023.9, 981.71]
z_0x,z_0y[mm]	[-1078.1 ± 32.0, -901.9 ± 22.5]	[1.046 , 0.928 ]
qx [mm]	1.078 ± 32.0 + 0.643 ± 38j	1.046 + 0.708j
qy [mm]	0.902 ± 22.5 + 0.604 ± 30j	0.928 + 0.651j
Beam radii at ITM [mm]	[54.442, 55.885]	[52.311, 54.385]

Beam radii at ITM is foudnfrom fit by propagating the fit q to the ITM.

Images attached to this report

H1 ISC - Whitening concentrators installed

daniel.sigg@ligo.org — Wed, 28 Jan 2026 11:52:06 -0800

Author: daniel.sigg@ligo.org

Report ID: 88947

We commissioned the 2 whitening concentrators in the ISC-R6 rack, after some of the chassis were rearranged, see alog 88922.

The whitening concentrators control the ASC-AS_C, the OMC_A and the OMC_B QPDs, and will in the future also control the ASC-LO_A and the ASC-LO_B WFS, as well as the ASC-LO_C QPD.

The slow controls software needed to be updated to support this.

All whitening controls channels were verified using the binary IO tester.

X1 DTS - Comment to SPI Pathfinder, Comprehensive Phase Noise measurements

joshua.freed@ligo.org — Wed, 28 Jan 2026 11:15:34 -0800

Author: joshua.freed@ligo.org

Report ID: 88944

Applying the equation found in 88293 to the data in the modified method, we get a new plot Keyrad3.png that shows the SPI noise budget for phase noise of oscillators used in the build/install of SPI. We can come to the same conclusion as last time, that since SPI has a reference interferometer the noise drops significantly at low frequency (the area where SPI operates). The noise from SPI's selected oscillators for the build/install is expected to have a negligible effect on our noise budget.

Images attached to this report

LHO VE - Wed CP1 Fill

david.barker@ligo.org — Wed, 28 Jan 2026 11:11:55 -0800

Author: david.barker@ligo.org

Report ID: 88945

Wed Jan 28 10:05:11 2026 INFO: Fill completed in 5min 8secs

Images attached to this report

H1 CDS - Comment to Tuesday afternoon DAQ restart for Beckhoff slow controls channel change

david.barker@ligo.org — Wed, 28 Jan 2026 10:05:33 -0800

Author: david.barker@ligo.org

Report ID: 88943

Tue27Jan2026
LOC TIME HOSTNAME MODEL/REBOOT
16:08:03 h1daqgds0 [DAQ] <<< 0-leg restart
16:08:10 h1daqfw0 [DAQ]
16:08:10 h1susauxh56 h1edc[DAQ] <<< EDC restart for new Beckhoff channels
16:08:11 h1daqnds0 [DAQ]
16:08:11 h1daqtw0 [DAQ]

16:16:15 h1daqdc1 [DAQ] <<< 1-leg restart, new daqd.
16:16:21 h1daqfw1 [DAQ]
16:16:21 h1daqtw1 [DAQ]
16:16:22 h1daqnds1 [DAQ]
16:16:31 h1daqgds1 [DAQ]
16:17:06 h1daqgds1 [DAQ]

H1 CDS - Tuesday afternoon DAQ restart for Beckhoff slow controls channel change

david.barker@ligo.org — Wed, 28 Jan 2026 09:58:18 -0800

Author: david.barker@ligo.org

Report ID: 88942

WP12980 DAQD code upgrade.

Jonathan, Daniel, Dave:

The DAQ was restarted at 16:08 Tue 27jan2026 for Beckhoff ISC-CS changes, applied when Daniel restarted the slow controls system earlier that afternoon. This was an EDC + DAQ restart.

We took this opportunity to complete the upgrade of DAQD on the 1-leg (it has been running on the 0-leg for over a week).

the 0-leg was a standard retstart, the 1-leg was a staggered restart node-by-node to implement the upgrade, followed by a full restart of the 0-leg.

H1 IOO - Comment to HAM1 update - JAC damper

jason.oberling@ligo.org — Wed, 28 Jan 2026 09:41:37 -0800

Author: jason.oberling@ligo.org

Report ID: 88941

Masayuki and I fully tightened the JAC body mode dampers yesterday. We were only able to get the screws ~1/2 turn past finger-tight before we could no longer tighten them. No changes in JAC alignment were observed while we were doing this.

H1 ISC - JAC EOM Heliax Cable Testing

marc.pirello@ligo.org — Wed, 28 Jan 2026 09:39:58 -0800

Author: marc.pirello@ligo.org

Report ID: 88925

I tested these in the morning with the Fieldfox TDR and found two of the Heliax terminations were bad on the HAM1 end of the run. I reterminated them and completed the install to the feedthrough, then took new TDR scans, they are uploaded here.

Images attached to this report

Non-image files attached to this report

CSVFiles.zip

JACEOMHeliax.xlsx

H1 SQZ - clipping of SQZ beam after cable dressing

sheila.dwyer@ligo.org — Wed, 28 Jan 2026 08:51:31 -0800

Author: sheila.dwyer@ligo.org

Report ID: 88939

Yesterday Rahul and I went to HAM7 to try to address the suspension problems reported in 88913.

I watched the beam on SQZT7 irises in the homodyne path while Rahul moved cables away from the suspended platform, the beam moved as he shifted the cables near the V3/H3 osems (the hard to reach ones) away from the platform, but not so much that we lost the beam. He also tried lifting the cable connector for the new translation stage on and off the OPO, this had a similar impact on the alignment but we never lost the beam.

We left the connector as it was, but moved the cables away from the platform. The beam coming out of the chamber was hitting the top of the upper periscope mirror on SQZT7, clipping somewhat there. We took the power meter in chamber and measured 20-30% losses between the beam leaving the platform towards the filter cavity and the beam returning in transmission of SFI1, which was pretty consistent with the power measured on SQZT7.

Jeff re-evaluated the suspension health 88921 yesterday afternoon. This morning from the control room I moved ZM1 in pitch -1800 urad which seems to have relieved the clipping according to the OPO IR TRANS PD, but has saturated ZM1 pitch. This can probably be offloaded to A:M3 to relieve the saturation.

H1 SUS - Comment to HAM7 OPO health check investigation - took fresh pictures (in chamber) for comparison, looking for cable inteferances.

corey.gray@ligo.org — Wed, 28 Jan 2026 08:37:59 -0800

Author: corey.gray@ligo.org

Report ID: 88938

EPO tagged

EPO

H1 ISC - Comment to JAC EOM update Friday Jan/23 (MattT, Mitch, Keita)

corey.gray@ligo.org — Wed, 28 Jan 2026 08:35:52 -0800

Author: corey.gray@ligo.org

Report ID: 88937

EPO tagged

EPO

LHO VE - Comment to Removal of the Relay Tube Viewport Assembly

corey.gray@ligo.org — Wed, 28 Jan 2026 08:33:08 -0800

Author: corey.gray@ligo.org

Report ID: 88936

EPO Tagged.

EPO

H1 SQZ - Comment to HAM7 and SQZT7 iris photos

corey.gray@ligo.org — Wed, 28 Jan 2026 08:30:20 -0800

Author: corey.gray@ligo.org

Report ID: 88935

EPO tagged.

EPO

H1 IOO - Comment to HAM1 update - JAC damper

corey.gray@ligo.org — Wed, 28 Jan 2026 08:27:57 -0800

Author: corey.gray@ligo.org

Report ID: 88934

EPO-tagged.

EPO

H1 SUS - Comment to 2nd HXDS received from LLO

corey.gray@ligo.org — Wed, 28 Jan 2026 08:25:59 -0800

Author: corey.gray@ligo.org

Report ID: 88933

EPO tagging

EPO

H1 SEI - BRS Drift Trends - Monthly FAMIS

oli.patane@ligo.org — Wed, 28 Jan 2026 08:25:42 -0800

Author: oli.patane@ligo.org

Report ID: 88932

Closes FAMIS#38813, last checked 88386

BRS Driftmon
Auxiliary BRS Channels

Everything is looking normal

Images attached to this report

H1 General - Ops Day Shift Start

oli.patane@ligo.org — Wed, 28 Jan 2026 07:32:13 -0800

Author: oli.patane@ligo.org

Report ID: 88931

TITLE: 01/27 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 4mph Gusts, 3mph 3min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.33 μm/s
QUICK SUMMARY:

LVEA is still LASER HAZARD

H1 ISC - Comment to JAC EOM update Tue/Jan/27 (Elenna, Keita, phone consultation with Valera)

valery.frolov@ligo.org — Wed, 28 Jan 2026 06:56:23 -0800

Author: valery.frolov@ligo.org

Report ID: 88930

I was also wondering why the S11 (return loss) is narrower then the transmission curve back when we did the prototype testing at LLO. So I did the math myself - the attached plot shows the calculated curves for voltage across the crystal for 1 W incident RF power and S11 for 9.1 MHz (similar for other f's). Initially I also made the same mistake estimating the Q - the Q is actually about 100 not ~1000 as one can see from the transmission curve (voltage on the crystal).

Images attached to this report

H1 ISC - Comment to JAC EOM update Tue/Jan/27 (Elenna, Keita, phone consultation with Valera)

keita.kawabe@ligo.org — Tue, 27 Jan 2026 23:35:57 -0800

Author: keita.kawabe@ligo.org

Report ID: 88929

Tuning is done, larger capacitance than obtained before with alumina, looks good. (But why do the dips have to be so narrow?)

We noticed that the frequencies were lower than what we have previously obtained with alumina, i.e. the capacitance is bigger. This is probably a good sign even though we don't know if this is due to the indium or something else. Especially, 118MHz dip was a MHz or two lower than nominal.

We were able to tune all four frequencies using trim cap, except that the trim cap for 45.5MHz hit the minimum and we could not increase the frequency any more, so we bent the winding of the coil a bit to spread loops apart. Below is the table of center frequencies (actual vs nominal). In the attached photos, cursor is placed close to the nominal frequency. They all look good in that the frequency is close enough to nominal that we're only loosing less than a dB, but the resonances are all very narrow (for my preference, anyway). The Q values are from 640 for 9MHz to 1300 for 118MHz, going higher as the frequency. A small change in frequency will result in a big degradation in the modulation depth.

(Added later: Read Valera's entry below, thanks Valera! The numbers here are not the real Q, they should be smaller. To make it more embarrassing, I somehow mixed up 3dB and 6dB. Given that all dips are smaller than -20dB, a quick thing to do is probably to define the width of the peak as full width of the -3dB points in S11, not +3dB points from the bottom but really -3dB measured from 0dB full reflection. If you do that the numbers are more like 100 instead of 1000.)

If you look at the pictures, you'll also notice that the reflection dips at the center are -23dB (9MHz), -24.5dB (24MHz), -23dB (45MHz) and is -25dB (118MHz) so a bit smaller than 10% in amplitude is coming back. It's not really matched to 50 Ohm transmission line, and that on its own is OK, but because of that, I wonder if we can add a bit of resistance to bring down Q values without any negative impact (like worse matching with increased reflections) in the future design.

Tuned center	Nominal	~~Full width of 6dB points from the bottom / Q~~
9.0995	9.100230	~~14.3k / 636~~
24.07705	24.078360	~~29.7k / 810~~
45.5043	45.50115	~~57k / 798~~
118.3055	118.30299	~~89k / 1329~~

After this first round of tuning, three set screws on the front plate were all extracted, and there was no change in the tuning of 118MHz dip.

I changed the orientation of the EOM and the frequency jumped a bit

Up to this point, tuning was done with the front plate facing down and put on the ceramic insulator placed on the EOM base (because it's convenient to access trim caps that way).

When I changed the orientation of the EOM so the front plate becomes upfront (i.e. like intended), the frequency of 118MHz dip shifted a bit, from 118.3055MHz to 118.31745MHz, it's just 12kHz shift so not the end of the world but it's still meaningful. Maybe it's the interaction of the magnetic field from the coil and the metals nearby?

Then I tapped the front plate and side plates and it shifted again, fortunately by smaller amount (from 118.31745 to 118.3113MHz, a negative 6kHz jump).

What we'll do tomorrow is to fully assemble the unit, tune it again as good as we can, then tap and retune if necessary. Hopefully, tapping enough and things will settle to the bottom of the potential.

Once the EOM goes into chamber we'll measure the resonances again, and we might have to retune in chamber.

Images attached to this report

H1 ISC - Comment to JAC EOM update Tue/Jan/27 (Elenna, Keita, phone consultation with Valera)

keita.kawabe@ligo.org — Tue, 27 Jan 2026 21:36:24 -0800

Author: keita.kawabe@ligo.org

Report ID: 88928

How crystal mounting was done.

We did "in-between" method (alog 88900) and inserted two pieces of 3/8IDx5/8ODx0.025" thick shim washers between the front plate and the input side plate. shim_washers_spacers.jpg shows the washers and the front plate before the rest of the EOM structure is placed on top. Note that the front plate still has the alumina piece on top, not the RTP. Important points in this picture:

We're using two pieces of alumina pieces as a convenient 4mm thick shim to raise the front plate. It doesn't have to be alumina pieces, but the front plate must be raised enough so the shim washers "clear the ground".
Three set screws are pre-adjusted so each sticks out just shy of 3.5mm. This is the height of the crystal (4mm) minus the depth of the shallow groove (nominally 0.02" or 0.508mm). This made it somewhat easier to to make sure that there's a good contact between the crystal and the metals.

(Added later: If I were to do this again, I'll set the set screws with alumina piece in place such that all touch the board when there's a good contact between board/plate/alumina (of course no indium). Insertion of indium foil with the real RTP later will automatically ensure that the screws are just shy.)

Next we cut a 40mmx4mm piece of indium sheet with a clean pair of scissors and installed it in a groove in the front plate. I tried to set the edge of the sheet to be 7.6mm from the outside edge of the front panel (this is 7mm plus the thickness of 0.025" washer). Judging from indium.jpg, I was mildly successful, maybe it's more like 7.4mm but it's not 7mm nor 8mm.

rtp.jpg shows the side view of the crystal. Maybe it's hard to see but it's wedged, in this picture the shortest face is down, the longest side is up.

I placed the crystal on top of the indium sheet, making sure that the edge of the crystal is well aligned with the edge of the indium as good as I can. We also made sure that the shortest face mates with the front panel. You cannot see any of that in the crystal_installed.jpg but you can at least see that the crystal is there.

Then we went through the same procedure we've already done more than several times, i.e. tighten the screws on the input panel until the panel touches the washer and the washer touches the front panel, tighten the scrwes on the output panel so the screws touch that panel, then go balanced tightening, moving just a tiny amount at a time, always applying small downward pressure for the EOM side/board/bottom assy otherwise the assy will shift when the screws are tightened. When all of the screws are tightened stronger than finger tight, screws on the input side are tightened just a bit more. After this, neither Elena nor I weren't able to undo screws by finger.

Sorry no picture of the assembled unit.

Images attached to this report

H1 ISC - JAC EOM update Tue/Jan/27 (Elenna, Keita, phone consultation with Valera)

keita.kawabe@ligo.org — Tue, 27 Jan 2026 21:00:30 -0800

Author: keita.kawabe@ligo.org

Report ID: 88927

Summary:

A day of success.

We installed the RTP crystal with "in-between" mounting method (alog 88900) with an indium foil between the crystal and the front plate but not between the crystal and the electrode.
Crystal is captured in EOM (no slipping out).
Frequencies before tuning were in general smaller than we got previously with alumina. Not sure if that is due to indium or something else.
Tuning was successfully performed.
The tuning was done with the front plate facing down on an isulator plate because it's easier that way. As soon as the EOM was oriented correctly, there's a small but non-negligible frequency shift. Tapping made a small change, too.
We will retune tomorrow with the correct orientation, tap repeatedly (in a hope that eventually we'll get to the bottom of whatever potential) and retune if necessary.

ISC

H1 AOS - HAM1 alignment work

masayuki.nakano@ligo.org — Tue, 27 Jan 2026 18:55:24 -0800

Author: masayuki.nakano@ligo.org

Report ID: 88926

[Jennie, Jason, Masayuki]

Summary:

We aligned the HAM1 output beam to the IMC and verified the power transmission through HAM2. The beam path through JAC_L2/L3 was centered, and alignment to the IMC was improved. Preparation for EOM installation is nearly complete, with final measurements planned for tomorrow.

Details:

IMC Alignment and Transmission Recovery:

We initially aligned the HAM1 output beam to the IMC. The IMC transmission signal (TRANS_NSUM) peaked at ~8 counts (with 30 dB whitening) under optimal alignment. However, after Jennie and Jason reverted the MC suspensions, the transmission dropped to <4 counts. We re-aligned JM2 and JAC_M3, successfully recovering the signal to ~6 counts. The second-largest peak was the TEM01 mode, approximately 1/6 the height of TEM00, which we considered acceptable for now.
Power Check on IOT2 Table:

With the recovered alignment, we measured 51 mW of power between the periscope mirrors on the IOT2 table. The HAM1 output was measured at 52 mW, confirming that no significant power loss occurred through HAM2. We then centered the output irises accordingly.
Beam Centering at JAC_L2/L3 and Final IMC Alignment:

The beam at JAC_L2/L3 was offset by about a quarter inch. We transversely shifted the lenses to center the beam, followed by re-alignment of JM2 and JAC_M3 to re-optimize the IMC transmission. Although JM2 adjustments typically disturb beam alignment through the lenses, only a single iteration was needed to restore IMC alignment. The peak height was slightly better than before this work.
Irises for EOM Installation:

Irises were installed between JM2 and JM3 in preparation for the EOM. With this, we believe most of the pre-installation alignment work has been completed.
Next Steps (Planned for Tomorrow):
- Measure polarization purity via IMC transmission.
- Measure the beam size on the IOT2 table.
- Perform finer alignment of the JAC input.
- Measure JAC throughput prior to EOM installation.

H1 CAL - PCAL EX End Station Measurement.

anthony.sanchez@ligo.org — Tue, 27 Jan 2026 17:42:40 -0800

Author: anthony.sanchez@ligo.org

Report ID: 88924

Dripta & I went to the EX to do a PCAL End station measurement followed by a TX module maintenance.

Obligitory Beam spot pic.
We followed T1500062-V21, with out much deviation until the measurements were finished. We did continue on with a TX module maintenance that we have not yet finished yet. Our plan is to go back tomorrow to finish the OLTF Optical Follower Servo measurement. We did leave the LASER HAZARD STATUS at EX in SAFE.

The ES measurement went smoothly.
Beam spot after ES measurement & TXmodule maintence!

python generate_measurement_data.py --WS PS4 --date 2025-11-03
Reading in config file from python file in scripts
../../../Common/O4PSparams.yaml
PS4 rho, kappa, u_rel on 2025-11-03 corrected to ES temperature 299.5 K :
-4.7017855975867215 -0.0002694340454223 2.686163396659873e-05
Copying the scripts into tD directory...
Connected to h1daqnds1
martel run
reading data at start_time: 1453573090
reading data at start_time: 1453573550
reading data at start_time: 1453573950
reading data at start_time: 1453574260
reading data at start_time: 1453574700
reading data at start_time: 1453575050
reading data at start_time: 1453575167
reading data at start_time: 1453575840
reading data at start_time: 1453576170
Ratios: -0.4588903912882054 -0.46880057152484483
writing nds2 data to files
finishing writing
Background Values:
bg1 = 9.720121; Background of TX when WS is at TX
bg2 = 4.686352; Background of WS when WS is at TX
bg3 = 9.770692; Background of TX when WS is at RX
bg4 = 4.628189; Background of WS when WS is at RX
bg5 = 9.797052; Background of TX
bg6 = 0.801247; Background of RX

The uncertainty reported below are Relative Standard Deviation in percent

Intermediate Ratios
RatioWS_TX_it = -0.458890;
RatioWS_TX_ot = -0.468801;
RatioWS_TX_ir = -0.453881;
RatioWS_TX_or = -0.463503;
RatioWS_TX_it_unc = 0.073150;
RatioWS_TX_ot_unc = 0.076593;
RatioWS_TX_ir_unc = 0.078168;
RatioWS_TX_or_unc = 0.089042;
Optical Efficiency
OE_Inner_beam = 0.989262;
OE_Outer_beam = 0.989063;
Weighted_Optical_Efficiency = 0.989162;

OE_Inner_beam_unc = 0.049361;
OE_Outer_beam_unc = 0.054133;
Weighted_Optical_Efficiency_unc = 0.073259;

Martel Voltage fit:
Gradient = 1636.767509;
Intercept = 0.537748;

Power Imbalance = 0.978861;

Endstation Power sensors to WS ratios::
Ratio_WS_TX = -1.077945;
Ratio_WS_RX = -1.393587;

Ratio_WS_TX_unc = 0.045600;
Ratio_WS_RX_unc = 0.039824;

=============================================================
============= Values for Force Coefficients =================
=============================================================

Key Pcal Values :
GS = -5.135100; Gold Standard Value in (V/W)
WS = -4.701786; Working Standard Value

costheta = 0.988362; Angle of incidence
c = 299792458.000000; Speed of Light

End Station Values :
TXWS = -1.077945; Tx to WS Rel responsivity (V/V)
sigma_TXWS = 0.000492; Uncertainity of Tx to WS Rel responsivity (V/V)
RXWS = -1.393587; Rx to WS Rel responsivity (V/V)
sigma_RXWS = 0.000555; Uncertainity of Rx to WS Rel responsivity (V/V)

e = 0.989162; Optical Efficiency
sigma_e = 0.000725; Uncertainity in Optical Efficiency

Martel Voltage fit :
Martel_gradient = 1636.767509; Martel to output channel (C/V)
Martel_intercept = 0.537748; Intercept of fit of Martel to output (C/V)

Power Loss Apportion :
beta = 0.998895; Ratio between input and output (Beta)
E_T = 0.994017; TX Optical efficiency
sigma_E_T = 0.000364; Uncertainity in TX Optical efficiency
E_R = 0.995117; RX Optical Efficiency
sigma_E_R = 0.000365; Uncertainity in RX Optical efficiency

Force Coefficients :
FC_TxPD = 7.900822e-13; TxPD Force Coefficient
FC_RxPD = 6.178276e-13; RxPD Force Coefficient
sigma_FC_TxPD = 4.646331e-16; TxPD Force Coefficient
sigma_FC_RxPD = 3.364222e-16; RxPD Force Coefficient
data written to ../../measurements/LHO_EndX/tD20260127/

Images attached to this report

Non-image files attached to this report

LHO_EndX_PD_ReportV5.pdf

LHO General - OPS Day Shift Summary

ibrahim.abouelfettouh@ligo.org — Tue, 27 Jan 2026 16:44:15 -0800

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 88923

TITLE: 01/28 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE for PLANNED MAINTENANCE

Good progress on activities today.

HAM7 - Cables were nudged in suspicion of rubbing due to OPO transfer functions that were "off" (alog 88917, alog 88913). The result were much better OPO Transfer Functions - alog 88921 Work will continue tomorrow.
HAM1 - Work has continued on the EOM which was successfully tuned, but there are still frequency changes that are unstable. Frequencies are 10, 20 kHz off. Work is continuing.
BSC2 - Inspection and walkabout.
EX - PCAL Measurements successful. They will transition to Laser Safe shortly.

Other:

Fire Pump Test at 10AM - successful
Beckhoff Restart
DAQ Restart
HVAC Work on airhandlers done across the site

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
22:49	SAF	LVEA IS LASER HAZARD	LVEA	YES	LVEA IS LASER HAZARD \u0d26\u0d4d\u0d26\u0d3f(\u239a_\u239a)	16:49
15:44	FAC	Nellie	LVEA	Y	Technical Cleaning	17:06
15:51	SUS	Betsy	LVEA	Y	BSC2 Inspection	17:51
15:51	FAC	Randy	LVEA	Y	BSC2 Inspection	16:22
16:01	FAC	Kim	LVEA	Y	Technical Cleaning	17:06
16:33	FAC	Richard	LVEA	Y	BSC2 Inspection	17:07
16:33	FAC	Randy	LVEA	Y	BSC2 Inspection	23:04
16:42	PCAL	Tony, Dripta	PCAL Lab	N	PCAL Meas.	17:13
17:10	FAC	Eric, Chris	EX, EY, MX, MY	N (YES EX)	Air Handler and HVAC Maintenance	18:28
17:14	PCAL	Tony, Dripta	EX	Y	PCAL Measurement	19:17
17:16	EE	Fil	LVEA	Y	Moving electronics by HAM6	20:21
17:33	ISC	Jennie	LVEA	Y	Turning on light pipe	17:35
18:06	FAC	Kim, Nellie	LVEA	Y	Technical Cleaning	18:44
18:08	SUS	Rahul	LVEA	Y	HAM7 OPO	18:31
18:14	TCS	Matt, Sophie	JOAT/Vac-Prep Lab	N	CHETA	15:14
19:05	EE	Marc	HAM1	Y	EOM Electronics	20:11
19:06	EE	Daniel	LVEA	Y	HAM6 Electronics	20:11
19:07	OPS	Oli	LVEA	Y	Reminding Daniel about a meeting	20:21
19:07	COC	Masayuki, Jennie	LVEA	Y	HAM1 EOM	20:45
19:08	SUS	JAson	LVEA	Y	HAM1 EOM	20:46
21:08	EE	Fil	LVEA	Y	HAM6 Electronics	23:06
21:11	PCAL	Tony, Dripta	EX	Y	PCAL Meas.	01:11
21:37	SUS	Sheila, Rahul	LVEA	Y	HAM7	22:48
21:45	COC	Elenna, Keita	Optics Lab	N	EOM	00:34
22:05	SUS-FAC	Travis, Jim, Betsy, Gerardo, Tyler, Randy	LVEA	Y	BSC2 Inspection	23:04
22:10	COC	Masayuki, Jason	LVEA	Y	HAM1 JAC	00:07
22:13	TCS	Marc, Jennie	Vac-Prep/JOAT Lab	N	CHETA Lable Table Cable	23:59
00:41	EE	Marc	LVEA	Y	EOM Reconnection	01:41

H1 SUS - Dramatic Improvement in H1SUSOPO TFs after Adjusting Cable Dressing; Still Some Work Tho

jeffrey.kissel@ligo.org — Tue, 27 Jan 2026 16:09:56 -0800

Author: jeffrey.kissel@ligo.org

Report ID: 88921

J. Kissel Took a set of TFs after Rahul and Sheila re-dressed the cables surrounding the H1SUSOPO (LHO:88920). The TFs -- especially Y to Y look a *lot* better with the higher frequency modes re-aligning with historical measurements and the model. There's still some mode splitting in the lowest mode, that I suspect is the transverse/vertical/yaw system not quite yet as soft as it used to was. Rahul mentions they did *not* address the cables that were zip-tied to the H3/V3 spring post so that could be it. We'll discuss and game plan more with the crew tomorrow. Data templates saved here: /ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_L_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_P_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_R_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_T_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_V_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_Y_0p02to50Hz.xml Again ran in the configuration where only the DOF being driven was undamped.SQZ

Non-image files attached to this report

alloposs_2026-01-27_H1SUSOPO_CableRubbingRelieved_ALL_TFs.pdf

alloposs_2026-01-27_H1SUSOPO_CableRubbingRelieved_ALL_ZOOMED_TFs.pdf

H1 CDS - Field Racks ISC-R5 and ISC-R6

filiberto.clara@ligo.org — Tue, 27 Jan 2026 16:05:25 -0800

Author: filiberto.clara@ligo.org

Report ID: 88922

WP 12991
WP 12994
D1200196 ISC-R5 Layout
D2400300 - ISC-R6 Layout
D1900511 - ISC/SQZ Wiring Diagram

In preparation for the installation of BHD, the following work was done to the HAM6 field racks:

1. ISC-R3 is now on its own set of power supplies for ±18V
2. ISC-R5 and ISC-R6 share a set of power supplies for ±18V
3. ISC-R3, ISC-R5, and ISC-R6 share a set of power supplies for ±24V
4. ISC-R5 was updated to D1200196-v15
5. ISC-R6 was updated to D2400300-v1

Racks are not complete. Missing electronics will be installed when available.

F. Clara, D. Sigg

ISC

H1 CDS - WP 12998 cont Installing the new VM cluster

jonathan.hanks@ligo.org — Tue, 27 Jan 2026 15:45:32 -0800

Author: jonathan.hanks@ligo.org

Report ID: 88919

Test stand log book entries that document the setup and testing prior to production

Physical layout

The following components are racked together in rack 12.

sw-msr-pve0 - switch that connects the nodes to each other and to the core. It runs the internal cluster traffic, and contains the links to the outside world.
1. Connected to the core via a lag. I have spare ports in both the core and the switch so that I can increase the bandwidth if needed
pve-node[0,1,2] - the nodes

Basic setup

When I updated the ipmi address in the bios I also did the install of the proxmox nodes. I follow the basic routine in reworking the proxmox setup for pve-node0.

Created a zfs raid z1 using /dev/sda & /dev/sdb
Gave the nics descriptive names:
- onboard 10g copper port 0 - nic1 - 10.20.0.50 (the web interface)
- onboard 10g copper port 1 - nic2 - not used
- solar flare 10g nic port 0 - nicdata0 - will be used as a bonded interface for VM traffic
- solar flare 10g nic port 1 - nicdata1 - will be used as a bonded interface for VM traffic
- intel e810 port 0 - niccluster0 - for the cluster corosync network
- intel e810 port 1 - nicceph0 - for the ceph networks

Repeat this for pve-node1 & 2, incrementing the ip addresses.

Cluster network configuration creation

Configured the niccluster0 interface on each node

Set to 10.200.0.50
Set mtu to 900
Set to autostart
Added comment "PVE Corosync Network"

Did the same on each node, and a ping test.

Cluster creation

On pve-node0 go to the datacenter / cluster and click on create cluster

Pick a name, "CDS-VM"
Select the 10.200.0.50 interface

Then on the other nodes to to datacenter / cluster and click join cluster

Get the join information from pve-node0 datacenter / cluster / join information, copy it to the clipboard
Paste the join information into the join window
Put in pve-node0's root password in the password box
Select the 10.200.0.5? link

Support subscription activation and updates

Now that the basic pieces are in place and will not need a reinstall, it is time to enable the subscription on each node.

Go to each node to the subscription section and upload the subscription key.

Now run updates against the enterprise repo and reboot each machine.

Configure the ceph network

Assign 10.201.0.5?/24 to the nicceph0 interface
Enable autostart
Set comment "Ceph Network"
Set mtu 900
Apply the configuration

Repeat for all nodes

Install Ceph

Go to datacenter / ceph page. When prompted, select install ceph

Install squid (Ceph 19.2)
Use the enterprise repositories
Do the install
Set the configuration
- Select the 10.201... interface
- Use the public network for the cluster network
- Set the initial monitor node as pve-node0
- Leave the replicas and minimum replicas values at default.
Go to the other nodes
- Only the install process is needed, not the config

Clean up disks

We had used these machines for other testing in the test stand, we will go through and clean up the disks prior to use.

remove partitions from the disks w/ fdisk (as needed)
then clean up the disk with "ceph-volume lvm zap /dev/sd[X] --destroy"

This was done on /dev/sdc and /dev/sdd on the systems

Create the Ceph OSD (Object Storage Deamon)

On each machine go to ceph/OSD

Create OSD
Disk /dev/sdc
DB Disk use OSD Disk
Encrypt OSD
WAL Disk use OSD/DB disk

Repeat for /dev/sdd.

After a minute they should show up on the ui.

Add more Ceph monitors

Add pve-node1 and pve-node2 as ceph monitors and managers.

Add a Ceph pool

pve-node0 /ceph / pool

Create Pool
name StoragePool

Setting up the VM data links, a bonded bridged network

Go to network / Create / Linux Bond

Name bond0
autostart
slaves nicdata0 nicdata1
mode LACP (802.3ad)
Comment VM Data Bond
mtu 9000
Apply Configuration

Create a data bridge, network / Create / Linux Bridge

Name vmbr1
autostart
vlan aware
Bridge ports bond0
Comment VM Data Bridge
mtu 9000
VLAN IDs 2 3 20 21 22 98 99 101 105 106

Do this on each of the nodes.

Notes

When creating VMs we want to connect the network to vmbr1 and specify the vlan tag that should be used as this setup gives us access to more than one vlan.

H1 SUS - Comment to HAM7 OPO health check investigation - took fresh pictures (in chamber) for comparison, looking for cable inteferances.

rahul.kumar@ligo.org — Tue, 27 Jan 2026 15:11:19 -0800

Author: rahul.kumar@ligo.org

Report ID: 88920

This afternoon Sheila and I went into the chamber and nudged some of the cables away from the OPO - Jeff will re-check the TF measurements to look for any improvements.

There is a cable connector sitting on the OPO (which is a new addition to the OPO). I lifted that cable connector and then Sheila looked for alignment shifts - which she confirmed. For now we left the cable connector at the same spot on the OPO. We will think of moving it away after Jeff's results.

Sheila also found some changes in the beam alignment since last week - not sure if this is due to our work (AOSEM re-centered LHO alog 88910) from yesterday - although centering aosem-flag should not change the mechanical alignment.

H1 ISC - Comment to JAC EOM Monday (Elenna, Keita, with remote help from Stephen, Michael, Matt and Gabriele)

keita.kawabe@ligo.org — Tue, 27 Jan 2026 13:06:55 -0800

Author: keita.kawabe@ligo.org

Report ID: 88918

Why (change in) the gap might matter.

Gabrilele asked me why a tiny gap matters so I made a quick calculation.

Suppose that we can ignore the edge effect at the edge of the electrode for convenience, we can replace the 4x4x40mm crystal with an infinitely wide and long crystal that is 4mm thick, and replace the capacitance with the capacitance per area.

In the attached, the electrode, the crystal and the face plate are all inifnitely larger in a plane orthogonal to the surface of my log book. Thickness of the crystal is d (4mm). There's a gap of delta between the electrode and the crystal, and there's no gap between the crystal and the face plate (but it's not important where exactly the gap is).

Under such a configuration, if you do the math, the capacitance per area is equal to the no-gap capacitance per area multiplied by 1/(1+epsilon*delta/epsilon_0/d) where epsilon and epsilon_0 are the permittivity of the alumina and vacuum, respectively, and the former is 10 times the latter.

In the end, the capacitance with the gap is a factor of

1/(1+10*delta/4mm)

smaller than without the gap.

The capacitance with a 0.1mm gap is 80% of that without the gap, 0.2mm and it's 67%, 0.3mm (12 thou) and it's 57%. If the gap doesn't change, maybe that's OK. If the gap changes it will change the tuning via capacitance change. There are other effects (like coil winding) but the capacitance change via the gap change cannot be ignored/dismissed.

Images attached to this report

H1 SUS - HAM7 OPO health check investigation - took fresh pictures (in chamber) for comparison, looking for cable inteferances.

rahul.kumar@ligo.org — Tue, 27 Jan 2026 10:59:57 -0800

Author: rahul.kumar@ligo.org

Report ID: 88917

Jeff, Sheila, Rahul

Details about OPO health check issues (Yaw dof. - frequencies are off and unnecessary peak observed) is currently being analyzed - see Jeff's alog 88913.

This morning we discussed about possible cable interferences in OPO.

I went into the chamber and took fresh pictures of the OPO from several angles, focusing on cable routing, cable resting on the OPO etc - please find them attached below. I will compare them with the pictures posted in LHO alog 61643 (by Sheila in 2022) and look for possible culprits (a few of them already).

Moving cables could cause some misalignment, hence we will start doing so once Sheila gives us a green light.

SUS

Images attached to this report

H1 SUS - H1SUSOPOS TFs post-OPO Crystal Swap / Translation Stage Improve -- Something Quite Off

jeffrey.kissel@ligo.org — Tue, 27 Jan 2026 10:48:56 -0800

Author: jeffrey.kissel@ligo.org

Report ID: 88913

J. Kissel, R. Kumar, B. Weaver, S. Dywer Context After the SQZ team felt done with OPOS suspension the re-install of the OPO (with an upgraded translation stage) we're following up on - Ryan's first look of the suspension's health (LHO:88851) - After restoring the OPOS to normal control system configuration (LHO:88872) - After recentering the AOSEMs (LHO:88910) Measurement I gathered more standard health check TFs. In doing so, I spruced up the excitation frequency response and data gathering templates to ensure good coherence. I also ran the TFs with all the damping loops besides the excitation degree of freedom ON to reduce incoherent motion from cross-coupling. The refreshed templates are /ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_L_0p02to50Hz.xml 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_P_0p02to50Hz.xml 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_R_0p02to50Hz.xml 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_T_0p02to50Hz.xml 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_V_0p02to50Hz.xml 2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_Y_0p02to50Hz.xml Results Attached is comparison of - the opos dynamical model (Equations of Motion matrices: ssmake_voposus.m rev 12322; parameter set: oposopt_h1susopo_fit rev 12322) - the most recent, best at-vacuum, measurement of L1's OPOS - the last, best, at-vacuum measurement of H1's OPO prior to moving from HAM6 to HAM7 - the last, bext, at-vacuum measurement of H1's OPO after moving to HAM7 (with a payload almost identical to what's installed now) - yesterday's measurement described above. Focusing on page 6 first, one can clearly see that YAW to YAW transfer function is wildly different, implying a significant change to the dynamics of the suspension. There's more supporting (but less signficant) evidence in - pages 1 and 2 which shows and increase in the primary L / T resonance from 1.25 Hz to a split 1.32 Hz / 1.39 Hz - pages 1 thru 6 (all diagonal elements of the TF matrix) and pages 7 thru 20 (most off-diagonal elements) all showing a huge (tho incoherent) resonance in yaw at 4.98 Hz that was not there before - Nominally an oversight in the design, the expected large V to Y coupling looks quite impeded. Discussion After conversing with Sheila about what might have changed, or what might be impacting the dynamics, she reviews the changes: - The OPO cavity assembly (D1500296) has only a few changes -- the translation stage within is new, and there are now thin remote-control cables coming out of the assembly that weren't present before. - Those new remote control cables have been bundled into a pre-existing bundle, potentially making the system stiffer. We guess that this is the likely culprit of our problems. - Further the re-placement of the OPO assembly on the OPOS was not precise. It's plausible that the physical location of the cavity is now *slightly* different position, *potentially* changing the balance and mass ratio of how much moving mass is in which translational DOF. Maybe the source of L / T resonance shifts, but I doubt it. Also, conversing with Betsy and Rahul about the state of cables they found while centering the OSEMs: - They see a collection of cables (OSEM and SQZ) on the "far" (+Y) H3/V3 side of the OPOS that are resting on the platform without a good, dressed, soft connection between the platform and where the cable stress is relieved on the base. Conclusion We need to address / free-up the dynamics of this suspension before closing up the chamber.SQZ, SUS

Non-image files attached to this report

alloposs_2026-01-26_H1SUSOPO_PostOPOCrystalSwap_HAM7Vent_Check_ALL_TFs.pdf

H1 TCS - Comment to CHETA Progress - second table

matthewrichard.todd@ligo.org — Tue, 27 Jan 2026 10:48:31 -0800

Author: matthewrichard.todd@ligo.org

Report ID: 88914

This morning we continued profiling to characterize the true L2 focal length and install the modeled telescope and characterize it.

We replaced L1 with L2 in the telescope and made several measurements to fit for a q-parameter after L2, because we think we know the q going into it quite well. Then with the q parameters, you can estimate the focal length using ABCD matrix for a thin lens (our estimates yield relatively low complex angles, less than 1 deg, making confident estimates).

Parameter	x [m]	y [m]
Input q (coming from the laser)	0.411 + 0.067i	0.376 + 0.056i
Output q (fit from profiles)	1.496 + 1.289i	1.221 + 0.632j
Focal Length (-q1/(q1/q2 - 1)	0.503	0.511

Average focal length of L2 = 0.507 m. Which is around 1.5% different from the spec'd value. To reiterate Sophie's log above, the focal length of L1 is estimated to be 0.217 m. Which is almost 9% different than the spec'd value. With these values in hand (as well as the updated value for CaF2 refractive index at 4.6um), we can make a more accurate model and see if measurements of the outgoing q-parameter from the telescope match that model.

We installed a telescope as set up in a model and measured several proviles to fit for the q-parameter after L2. The modeled waist size in both the horizontal and vertical are within the fit uncertainty; however the waist position of the modeled beam is roughly 20cm off in both directions. I think this is because of the Gouy phase regime that we are sampling gives better estimates of the waist size and since we did not sample near the waist we do not have a good idea of where it is.

This afternoon we will try and re-build the telescope as optimized in our models with these measurements to see if we can get a q-parameter that will be 53mm at the "ITM" (propagated 35m from L2).

Images attached to this report

H1 IOO - Restored sliders on IMC SUS to December 3rd state

jennifer.wright@ligo.org — Tue, 27 Jan 2026 10:42:54 -0800

Author: jennifer.wright@ligo.org

Report ID: 88916

Jennie W, Jason O, Sheila D, Masayuki N,

Following Jim bringing HAM3 HEPI online (alog #88909) and isolating HAM3 ISI.

Jason and I restored the MC1, 2 and 3 sliders to their position on December 3rd during a lock when the mode-cleaner was locked with 2W input, HAM2 and 3 ISO Gain was , HAM2 and 3 ISI Guardian was set to 'isolated' and 2 and 3 HEPI guardian was set to 'RoBUST ISOLATED'.

This lock state for the IMC Guardian is 100.

Before any adjustments today, we had 45 dB whitening gain on MC2 trans, and 91% of the power was in the 00 mode. This gave us 46 counts on MC2 trans nsum.

After HEPI, ISI, and suspensions are restored, we have mostly 10 mode, with 17.9 counts on MC2 trans sum, still 45 dB whitening gain.

I lowered the whitening gain to 30 dB to restore us to the normal whitening gain.

If we restore the alignment so that 90% of the power is in the 00 mode again, we should have 8.2 counts MC2 trans nsum

ISC, OpsInfo, SEI

Images attached to this report

LHO General - HVAC fan bearings greased

eric.otterman@ligo.org — Tue, 27 Jan 2026 10:36:32 -0800

Author: eric.otterman@ligo.org

Report ID: 88915

All fan bearings at Corner, Mids and Ends were greased this morning.

LHO VE - Tue CP1 Fill

david.barker@ligo.org — Tue, 27 Jan 2026 10:13:02 -0800

Author: david.barker@ligo.org

Report ID: 88912

Tue Jan 27 10:06:26 2026 INFO: Fill completed in 6min 22secs

Images attached to this report

LHO General - Comment to OPS Day Shift Start

david.barker@ligo.org — Tue, 27 Jan 2026 10:09:30 -0800

Author: david.barker@ligo.org

Report ID: 88911

Fire pump alarms bypassed for next 4 hours while churn testing is ongoing.

H1 SUS - HAM7 work - OPO AOSEMs (H1, H2, H3) re-centered.

rahul.kumar@ligo.org — Tue, 27 Jan 2026 09:50:06 -0800

Author: rahul.kumar@ligo.org

Report ID: 88910

Karmeng, Betsy, Jeff, Rahul

Following the recommendation given in LHO alog 88872, yesterday (01/26/2026, Monday) we went into HAM7 chamber and re-centered the three horizontal AOSEMs (H1, H2 and H3) as best as we could. All three AOSEM counts (raw inmons) are now between 11-15k.

Next, Jeff will re-take the transfer function measurements and confirm if OPO is healthy.

Also, Sheila et al will re-confirm if the beam is well aligned with other suspension in HAM7 chamber.

OPO is currently unlocked and suspended.

SUS

H1 SEI - Current seismic state in the corner

jim.warner@ligo.org — Tue, 27 Jan 2026 09:48:30 -0800

Author: jim.warner@ligo.org

Report ID: 88909

Because there was some confusion about the mechanical states in the corner station, I'm posting a summary of things as they stand today. The only HEPIs that are locked are HAM1,2 and BSC2, and HEPI Isolation are still bypassed. The white board in the control room says HAM1-4 are locked, this is not true. I have re-enabled the isolation loops for HAM3 HEPI (set H1:HPI-HAM3_ISO_GAIN to 1) and set HAM3 SEI back to ISOLATED. HAM1&2 HEPI are still bypassed. HAM1 & 7 ISI are also still locked.

HAM1,2, BSC2 HEPI - LOCKED, BYPASSED

HAM1,7 ISI - LOCKED

Everything else should be able to be run as normal.

H1 SUS - Comment to Current Status of SUS-C1/C2 Racks vs Final O5 Build

oli.patane@ligo.org — Tue, 27 Jan 2026 09:21:35 -0800

Author: oli.patane@ligo.org

Report ID: 88908

To clarify a bit on the status of SUSB13 and SUSB2H34, "as of these Jan 2026 changes, the SUSB13 racks and IO chassis are 'fully upgraded,’ as only the ITM QUADs are left in this system and there are no changes to the QUAD control system electronics for O5, and we’ve now upgraded the whole chassis to use 28-bit 32CH LIGO DACs. For the SUSB2H34 racks and IO chassis, while we’ve imported the existing BSFM beam splitter control system electronics, that’s all we can do at this point and we need the BS under control as it was for the Feb 2026 commissioning period. After that’s done, and as the suspensions get installed, we’ll add electronics to upgrade the BSFM BS to become a BBSS BS (with M1 QOSEMs replacing the M1 BOSEMs, and new M3 OSEMs for sensing and control there), and we install the LO1 and LO2 HRTS electronics for BHD as needed. So, it may be a while before the wiring diagrams match reality again".

(Thanks to Jeff for the clearer wording!)

H1 CDS - Move cdswiki server to make space for new cluster

david.barker@ligo.org — Tue, 27 Jan 2026 09:03:44 -0800

Author: david.barker@ligo.org

Report ID: 88907

WP12997 Jonathan, Erik, Dave:

The cdswiki server, which actually is now just our CDS Apache web server after the wiki moved to GC, was physically moved from MSR-RACK12 [U17,18] over the MSR-RACK11.

We decided to put it where the unpowered netmonitor machine was in U16,17. The netmonitor machine was removed and is now in H2 storage.

cdswiki has only a 10.20 ethernet cable connection, I used a shorter 6-footer (E5B-006-0001) which was dangling in the rack.

H1 CDS - Comment to VACSTAT alarms for EY BY Ion Pump Issues 00:09:33 Tue 27 Jan 2026

david.barker@ligo.org — Tue, 27 Jan 2026 08:37:37 -0800

Author: david.barker@ligo.org

Report ID: 88906

vacstat_ioc.service was restarted at 07:57 to reset this alarm.

LHO General - OPS Day Shift Start

ibrahim.abouelfettouh@ligo.org — Tue, 27 Jan 2026 07:55:32 -0800

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 88905

IFO is in IDLE due to PLANNED MAINTENANCE

Work continues on in-chamber JAC alignment and EOM work is continuing (RTP installation planned for today). Work is being done to close out HAM7.

H1 CDS - VACSTAT alarms for EY BY Ion Pump Issues 00:09:33 Tue 27 Jan 2026

david.barker@ligo.org — Tue, 27 Jan 2026 07:53:01 -0800

Author: david.barker@ligo.org

Report ID: 88904

VACSTAT detected a gas release at EY originating at the EY BT Ion Pump and rapidly propagating to EY. Cell phone alarms were sent to team-VAC.

Gerardo determined that the Y2-8 ion pump turned off for 1 min 41 seconds and then recovered.

Images attached to this report

H1 CDS - Workstations updated

erik.vonreis@ligo.org — Tue, 27 Jan 2026 06:51:29 -0800

Author: erik.vonreis@ligo.org

Report ID: 88903

Workstations were updated and rebooted. This was an OS packages update. Conda packages were not updated.

CDS