The annual maintenance was done on the chillers at both End Stations this morning. 

Tue Feb 03 10:07:42 2026 INFO: Fill completed in 7min 39secs

Dave confirmed a good fill curbside.

Last Checked Jan6 (alog 88698).

NOTES:

• LAB2 looks OFF (noted last back in Sept)--will send a note to RyanC on this one.
• PSL 101 & 102 (0.5um particles) pretty much zero the last month, but do have 10min of 10 counts a couple times.
• DR1  (0.5um particles) also pretty much zero the last month, but has had some dust counts 3x in the last month.

TITLE: 02/03 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: 10mph Gusts, 7mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.47 μm/s 
QUICK SUMMARY:

Reminder that the LVEA is LASER SAFE EXCEPT around HAM1/2 and at height.

Summary

We improved the IMC mode matching by repositioning JM2 and JM3 based on the calculation from yesterday. The mode mismatch was reduced from about 10% to ~2% after iterative alignment and mirror position optimization. Further improvement is expected with additional calculations and tuning, which will be continued tomorrow.

Details

We worked on improving the IMC mode matching following the calculation from yesterday. As a first step, JM2 was moved by approximately 3 inches; the new position is shown in the attached photos. The alignment to the IMC was performed using the newly placed iris in front of JAC_L2 and the iris after the output periscope, as described in the previous alog. By centering these two irises, the alignment could be brought to the level where IMC flashes were visible. From that point, adjusting JM3 allowed us to easily reach an alignment where the TEM10 content was at the ~10% level.

After achieving a reasonable alignment using a scratched mirror, we replaced it with a newly cleaned narrow-angle mirror for JM2. The scratched mirror was moved to JACR_M1. As a note, the scratch was oriented on the +y side; by keeping the beam closer to the −y side, the impact of the scratch was minimized.

With this configuration, the mode mismatch improved from about 10% to approximately 4%. Since the calculation suggested that further improvement should be possible, we continued tuning by adjusting the JM3 position. Based on the previous calculation indicating an offset in JM3, we first moved JM3 by about 1/2 inch in the −x direction (increasing the L1–L2 distance). This resulted in a degradation of the mode mismatch to about 6%. We then moved JM3 in the +x direction by a total of 1.5 inches (i.e., 1 inch further from the original position), effectively shortening the L1–L2 distance. With this adjustment, the mode mismatch recovered to approximately 2%.

We stopped the work at this point and plan to perform updated calculations tomorrow to guide the next iteration of tuning.

TITLE: 02/03 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
LVEA was Bifircated via a Laser Hazard areas around HAM 1& 2, while the rest of the LVEA is LASER SAFE unless at height. See M2600004 for details.

PM1 was mysteriously dancing & Saturating too much for Rahul's transfer function measurement all day long. While he was troubleshooting. Update!!! Rahul dragged the EE guys out and found a dead Coil Driver! Mystery solved!

JAC work continued all day starting with mode matching in HAM1, and starting a JM2 swap. JAC table now has all the mounts and Cables but no optics yet. 

HAM7 & ITMY ISI Watchdogs tripped at 23:33 UTC due to mysterious high frequency ground noise that was louder at HAM7 than ITMY.  Jim & Betsy went to go look for fallen wrenches or other watchdog tripping phenomena..... No explanation was ever found. 

OPS info: 
New conda ENV doesn't run watchdog untripping scripts unless you run Conda Kill first.  Tagging CDS. 

LOG:

Dave, Oli, Marc, Fil, Rahul

This morning I switched PM1 (Tip Tilt suspension) in HAM1 chamber from safe state to damped state and immediately the DAC output was saturating. I suspected purge air (which Travis turned it down twice during the day) and later Masayuki also covered PM1 with foil. However, nothing stopped the suspension from saturating.

Then Oli, Dave and I did a model restart and later I power cycled the Satamps for PM1 in the LVEA - nothing helped.

Next, Marc, Fil and I went to the LVEA (checked the satsamp, which was fine) and CER and found the Coil Drivers to be faulty.

New Coil driver - E2400048 s/n 22001180

Old Coil Driver - E2100430 s/n S1106046

SUS PM1 is now not saturating. I will perform the heath checks later on.

Just noting that this kind of thing can happen when platforms are in different states. Something caused large-ish high frequency ground motion in a short burst this afternoon and tripped HAM7 and ITMY, because those chambers were damped, but not any of the other chambers because they had high gain isolation loops running, or were already tripped/locked. What ever it happened was louder at HAM7, than the ITMs, as shown in the top left of the attached plot. Because the motion was high frequency, where the isolation loops had enough gain to keep the ISI seismometers from saturating, only HAM7 and ITMY tripped because their isolation loops were off, and damping only engaged. And the event was small enough to not saturate the actuators.

Oli, Rahul, Tony, Marc, Fil, Daniel, Dave.

At 15:41 we restarted the h1susham1 model as part of the PM1 noise investigation. This did not change anything.

Later (16:40) Marc and Fil found that the problem was a dead power rail in the PM1 coil driver.

Used 1W into JAC.

9 (26.8dBm into EOM), 45 (27dBm) and 118MHz (10.76dBm) -> Used a single bounce beam from ITMX and scanned OMC. Successful for 9 and 45, nothing visible for 118. Detailed will be posted later.

24MHz (IMC, 14.2dBm) -> Scanned IMC length and tried to find something in IMC transmission. Nothing visible.

43MHz (JAC, 12.2dBm) -> Scanned JAC, saw nothing in JAC transmission. Boosted RF  power with an amp to 29.67dBm -> m=0.092. Without the amp modulation index would be 0.012.

Jennie W

This morning I re-centred the beam on MC TRANS in-air camera on IOT2. This was using the IO_MCT_M5 mirror, see layout here.

I did this while the JAC was locked and the IMC was flashing through modes.

I only had to move the steering mirror in yaw to centre the mode flashes on the camera.

As noted on Friday, RLF QPD A segment 3 railed Nov 29th, and has been railed since then.  

Filiberto, Kar Meng, Marc and I went to the rack and swapped the two cables for WFS1 + WFS2 on D2000552.  The saturaed segment moved with the cable which could indicate the problem is the in vacuum QPD.  

The 105kHz segment went quiet at the same time as the problem on the DC segment.  This happened on a Saturday, before the chamber was vented.  It had been two days of not locking the squeezer or the IFO before this happened.  

Edited to add:  This is the QPD used for filter cavity length control.  We did lock the filter cavity after the segment broke, December 4th.  

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.

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.

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.