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

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.

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.

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. 

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

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.

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!





 

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:

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 : 

 

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.

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 

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

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.

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

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.

J. Freed,

Continuing From 88293, I took phase noise measurements of waveform generators relevant to SPI pathfinder with two different methods. This first method is the standard method that LIGO uses which follows the BluePhase 1000 manual. I used this method to highlight the issues this method has in the context of SPI. The second method is a slight modification to the standard method which shows a lower noise floor in the area of interest for SPI.

First Method:  BluePhase1000_Setup.png (from LIGO-T2400324) Shows a simplified Phase noise measurements set up of what the BluePhase 1000 manual provides. A simple way to take phase noise measurements is to mix the signal from the Device under Test (DUT) with a reference device (REF) outputting the same frequency but at quadrature. Ideally, this mix outputs only the differential noise between the two devices. If the reference device has much better performance, then the mix ideally outputs only the DUT noise. In this method, a feedback loop is used to keep the REF at quadrature with the DUT. For the REF device, I used the 80MHz OCXO housed in LIGO-D1100663. 

OCXOComparisonTOCXO.png Shows the results from the first method, I used 3 different devices as the DUT; a 80MHz OCXO here at LIGO LIGO-S1000565, a SRS SG382, and a Keysight 33600A. The main thing of note is that OCXO is expected to have a much lower noise floor than any other device; however, below ~60Hz the noise is not limited by the different DUTs. Since the REF is another OCXO, I believe the feedback loop that keeps the REF device in quadrature is limiting measurements below 60Hz.  Since SPI is interested in phase measurements well below 60 Hz this first method will not work for taking phase noise measurements for SPI. Especially since SPI has both an 80Mhz and an 80MHz -4096Hz signal and LIGO  does not have a 80MHz -4096Hz OCXO to use as a ref. 

Second Method: PhaseNoiseSetUp.png shows the modified set up; where the REF device is the SRS SG382. This method puts the REF device at quadrature by setting it manually and holding it there through the 10MHz timing port created by dividing by 8 the 80MHz OCXO signal. Since both the REF and DUT are referenced to the same OCXO (or the DUT is the OCXO itself), ideally both devices will be held at quadrature bypassing the need for a feedback loop. In practice, I did notice a small amount of drift from quadrature over time. 

OCXOComparisonSRS.png Shows the results from this method. This graph shows both the OCXO and the Double Mixer have phase noise performances well below the noise performance of a typical waveform generator (Keysight) below 100Hz. Though combined with the last alog, still very much better than SPI requirments.

Difference: OCXOComparisonSRSOC.png (ignore the title on this plot) shows the mix of an 80MHz OCXO and the SRS using the two different methods to hold one at quadrature with the other. With the modified method, we are not limited as much below 60Hz, except those peaks at ~0.16Hz, ~0.45Hz, etc.. which I believe are caused by the divide-by-8, not the SRS; as the SRS measurement using the first method did not have these peaks. 

Extra:

OCXOComparisonFull.png Shows all measurements on one graph.

OCXOComparisonKey.png Shows that Keysight had strange harmonics at multiples of 5kHz but disappeared 12 hours later. 

Jason. JennieW, Rahul

This morning we added the damper parts to the JAC in HAM1 chamber - see picture attached. The cables were re-routed slightly so that they don't interfere with the damper.

I have finger tightened the screws of the damper for now - since no torque spec was provided and we were worried that tightening them too much might affect its position/angle.