Here we study the effect of thermal deformation on the SRCL detuning as we increase the input power. This work shows a more signifcant impact of the spherical aberrations and HOM thermal distortions on the SRCL detuning than the mode mismatch, or misalignment. 

Building on the previous study of how mode mismatch affects SRCL detuning, I now turn to exploring the thermal effects on SRCL detuning. When laser light passes through optics, a small portion of it is absorbed, leading to some heating. This thermal absorption causes the optic to either physically deform or develop a refractive index gradient both of which can distort the wavefront. More background on this process is available.

A thermally distorted thin lens can be thought of as a combination of a quadratic lens term and a residual distortion that includes spherical aberrations and other higher-order modes. In FINESSE, we simulate this by generating an optical path difference (OPD) map based on the absorbed power. We then fit and subtract the quadratic component, which corresponds to the ideal thin lens (the effect explored in the earlier study). The remaining residuals represent the non-quadratic distortions we’re now interested in analyzing for their impact on SRCL detuning.

It’s important to note that in this model, the cavity geometry like, the radius of curvature remains unchanged. As a result, mode mismatch is not a factor in this part of the analysis.

These residual distortions have a stronger effect on detuning than the lensing term alone, as shown in the plots below. This model assumes 0.13 ppm absorption in the ITM coatings. The model fails to lock with higher absorption values. No thermal effects are applied to the ETMs in this analysis.

• The first plot shows how SRCL detuning changes as the input power—and thus the circulating power—increases from 10 W to 60 W. The right-hand y-axis shows the percentage change for reference.
• The second plot illustrates how the sensing functions shift with increasing power. These are normalized to their value at 100 Hz for easier comparison. When compared with earlier results, the impact of thermal distortion on the sensing function becomes clearly visible at low frequencies.

TITLE: 05/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

GRB-Short E571183 @ 15:36:28
Test T571184 @ 16:00:09
EX N2 fill completed.
Water tank taken to EX to wate the sand.
SEI BRS upgrade work continues , possibly pump down tomorrow.

LVEA has been transitioned to LASER SAFE

LOG:

Closes FAMIS37252, last checked in alog83817

The diode room DM was having some issues that I fixed the other week, lab2 is also a known issue. No other issues of note.

Betsy, Ibrahim

Today, Betsy and I replaced the non-plated BBSS bottom wire loop with the gold plated wire loop, which was done successfully and took roughly two hours. We've confirmed the BBSS is centered and aligned. We will monitor and inspect the BBSS in the next few days and coming week. Stay tuned for new transfer functions etc.

Gallery of the wire loop below!

- Cable table bracket for the bosem cables have been added to RM1 suspension in HAM1 - see here.

- Beam dump for catching the transmitted light through PM1 optic has also been attached as shown in several pictures attached below. Camilla and I adjusted/fine-tuned (angle etc.) it as well.

Also, I thoroughly inspected PM1 (BOSEM flags and mirror holder) for any rubbing or touching, didn't find anything. I adjusted the BOSEM bracket for my own satisfaction, since one or two of the BOSEM flags were not exactly looking centered between the PD/LED, however the adjustment was minimal (the bracket could hardly move) and didn't create much of a difference. I will be posting the measurement results asap.

Betsy, Jenne, Camilla

Day 1: 84193, Day 2: 84228, Day 3: 84230 and 84239, Day 4: 84274, Day 5: 84292, Day 6: 84314, Day 7: 84334, Day 8: 84361

This morning we finished our last laser hazard tasks in HAM1 mainly at 20W in, did some final checks and went back to laser safe. 

POP LSC Pico: This pico was too close ot the edge of its range so I turned the mirror mount so there was range and realigned onto the center of the POP LSC diode. 

• Two secondary off the REFL BDV1 that are ghost beams from the intal M7/M1/M17 optics transmitted through M1 but too close to block well before the beam divertor. As our low noise state is with this BDV1 closed, we changed the size of the places in BD5 to catch all three beams (main + 2 ghost). Note that these beams when reflected off M1 are blocked by BD7 and BD8. 
• There as also a beam being defected very low from ASC REFL B and bouncing off the ISI table, Betsy added a beamdump without post to catch this on the -Y side of the SLED. NO beam like this off the other ASC diodes. 
• Betsy and Jenne could a faint beam and disc on the +Y septum door but we couldn't understand where these were coming from. 

Final Checks: We checked ndscope for all LSC and ASC diodes while blocking and unblocking the beam to check there was signal on all. Yesterday Elenna and I removed all of the temporary metal name tags and this morning I checked that there were no thumb knobs left on any optics. As it doesn't make sense for PM1 to be misaligned, we suggest having misaligned offsets of (0,0) for this, although if we really wanted, a setting of (1500,1500) would ge the beam off the diodes. 

Have lots of component photos that will be attached later. 

Betsy, Camilla

PSL locked out at 2W. ALS shutter closed. LVEA now in laser safe.

Now nearing closeout of HAM1 ISC/IO (Final cable routing tweeks, SEI table float/bal, and final SUS TTs up next for a day or so):

Updated Tuesday 13th May to mark the following as DONE: finish BDs in front of POP diodes, 4 Pico-motors tested, center-ish in range, Finish aligning all beam dumps, Removed temp mirror knobs. All laser hazard tasks completed (we may do a final check before closeout). 

WP12529

Jonathan, Erik, Daniel, Dave:

The EDC on h1susauxb123 was restarted to ensure a clean connection to the Beckhoff slow controls EPICS channels. Following Daniel's restart of the slow controls IOC yesterday for a code change, it was noted that the EDC was still serving the old value while caget was reporting the correct value. Later when the channel was manually switched the EDC obtained and served the correct value. Testing of a random sample of about 400 channels out of 35,588 did not find any other channels in error, but to be sure we did the EDC restart this morning.

No full DAQ restart was required.

The EPICS channel data gap while the EDC was being restarted was 27 seconds. Attached plot of a vacuum channel shows the details.

Tue May 13 10:11:08 2025 INFO: Fill completed in 11min 4secs

Gerardo confirmed a good fill curbside.

Dry air skid checks, water pump, kobelco, drying towers all nominal.

Dew point measurement at HAM1 -45.8 °C.

TITLE: 05/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 5mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.29 μm/s
QUICK SUMMARY:
Workstations have already been rebooted.

Remember the LVEA is still lazer Hazard.

The Expected Work today: 

Corner station:
Restart the EDC
Workstation Updates Completed
LASER HAZ HAM1 Beam alignment work
HAM1 ISC close out  work for payload balancing
VAC Ham1 Top flange guage work
PEM PEM Coil work by clean bay
HAM1 Cable tray & cable straighting
HEPI upgrade, Software part start ?

EX - Bee aware of the bees in the area
Wind Fence Work at EX
ALS beam profiling & troubleshooting

EY
SEI BRS work
ALS beam profiling & troubleshooting

Mid stations:
chiller work

Dust mons outputs :

300nm Minor alarm do not match dcc levels for LVEA5, Clean room on?
500nm Minor alarm do not match dcc levels for LVEA5, Clean room on?

300nm Minor alarm do not match dcc levels for LVEA6, Clean room on?
500nm Major alarm do not match dcc levels for LVEA6, Clean room on?

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

TITLE: 05/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Started the day by restoring alignments of BS and ITMs to locations on Friday according to top-mass OSEMs following the h1susb123 crash yesterday. More progress with HAM1 today; ISCT1 and the viewport simulator were moved off the chamber and alignment of the POP diodes proceeded. Slow controls was restarted to fix a logic issue with the REFL beam diverter. Wind fence work at EX continued but ended early due to escalating wind speeds this afternoon.
LOG:

[Shoshana, Michael]

We've started preparing to install the BRS mass adjuster to the End-Y BRS. The plan is to follow the same procedure/same parts as the End-X install outlined in LIGO-T2400043 and SEI log 1886 (https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=1886).
 We've taken apart the BRS and discovered that doesn't match the designs on the DCC. How the parts are arranged blocks access to where the pico-motor mount should attach, but we think we have a work around that should work.
The electronics/wiring of the BRS is as expected and we've finished all the wiring for the pico-motor so that it should attach to the feed through.
Assuming all goes well we plan on installing the mass adjuster parts and begin testin.

Sheila, Betsy, Tyler, Oli, Jennie, Camilla, 

Day 1: 84193, Day 2: 84228, Day 3: 84230 and 84239, Day 4: 84274, Day 5: 84292, Day 6: 84314, Day 7: 84334

PSL ALS: we decided that the PSL ALS path was too close to the edge to the VP (84334) we tried moving M13 so the beam traveled in-between M11 and L2 but this didn't give enough separation at the bottom pericope mirror of ISCT1. We then put M1 back to a similar position to wear we started an decided that it was good enough away form clipping the VP. Photos attached of M15 location, beam on M15, beam next to L2, VP simulator, UPM, LPM.

Betsy, Camilla, Keita

Follow up to 83605.

I created a few templates to do a SR3 OSEM calibration. I called them

sus/trunk/HLTS/H1/SR3/Common/Data/
yyyy-mm-dd_hhmm_H1ISIHAM5_ST1_WhiteNoise_ISO_{X,Y,Z}_0p05to40Hz_calibration.xml

The measurement should be run with all gains on SR3_M1_DAMP_{L,T,V,R,P,Y} set to - 0.1 . Just to make sure the loop gain does not mess with the OSEM measurement of the cage above resonance.

The idea is that we ought to be able to only use the cartesian measurements of the ISI to calibrate all the OSEMs in the suspensions attached by using linear algebra. This is the first pilot for that idea. We want about 100 points between 5-10Hz to make sure we can make a "decent" fit.

___

When Oli runs these templates, the plan is to use them to calibrate the SR3 OSEMs for the estimator work (see 84171 for the latest news as of the making of this post).
We will use Oli's feedback to work out the kinks of the calibration procedure and to export it to other ISIs at a later time.