Edgard
I added two matlab scripts to find the multiplicative correction factors for the OSEM calibrations by using the ISI Suspoint drives, as described in 83605. The script is still a work in progress, but it should be compatible with lightly damped ISI-to-M1 measurements like the ones in 83940 and 80863.
The scripts live in
/ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/
and they are
extract_HLTS_ISI_dtttfs_for_OSEM_calibration.m HLTS__ISI_to_OSEM_calibration.m
I will post the calibration comparisons with in air calibrations later.
We've had an excellent week of progress on the estimator - thanks to everyone on site for the great hospitality!
Status of things as we go
1. The estimator is OFF. We set the damping of M1 Yaw back to -0.5.
2 There are new YAW estimator blends in the SR3 model. These were put into foton with autoquack. The foton file in userapps was committed to the SVN
3. We updated the safe.snap SDF file with a decent version of the OFF estimator. We HAVE NOT updated the observing.snap file. At this point, all the estimator settings should be the same in safe and observing. (I'm not sure how to update the observing.snap file)
4. All the work on the estimator design is all committed to the {SUS_SVN}/sus/trunk/HLTS/Common/FilterDesign/Estimator/
-- some detailed notes on the blend design and svn commits follow --
Design new blend filters, load them into the model, commit the updated foton file
seems like a 2% error in the peak finding makes a bunch of noise in the estimator with the agressive blend, and is not a reasonable error (judgement call by Brian and Edgard)
>> print -dpng fig_2pcnt_error.png
>> print -dpng fig_2pcnt_error_result.png
Check noise again with 2% error in model/actual using the robust blend (EB blend) - we see the peaks are not any better.
I can't get a broad notch for notch 3 without causing the OSEM filter to be larger than 1. Issue seems to be the freq of the notches going past 60 deg. Could be tuned further.
Instead - use a simple notch. This means we'll need to be quite accurate with the 3 peak - probably withing 0.5% of the actual frequency
figures
gain error - no performance hit
2% freq error - clear perf hit
1% freq error - acceptable perf hit - top mode clearly worse, but only a little
0.5% freq error - tiny perf hit at top mode only
print -dpng fig_perf1_gainerror.png
>> print -dpng fig_perf2_0p5freqerror.png
>> print -dpng fig_perf3_1p0freqerror.png
>> print -dpng fig_perf4_perfectmatch.png
turn the script into a blend design script - Estimator_blend_doublenotch_SR3yaw.m
update the yaw frequencies to 1.016, 2.297, 3.385
can we use autoquack? - yes!
Real foton file is: /opt/rtcds/userapps/release/sus/h1/filterfiles/H1SUSSR3.txt
(make a backup copy): /opt/rtcds/userapps/release/sus/h1/filterfiles$ cp H1SUSSR3.txt H1SUSSR3backup.txt
the file make_SR3_yaw_blend.m uses autoquack to put the new filters into the SR3 foton file.
(log notes)
please review the recent foton -c log file at
/opt/rtcds/lho/h1/log/h1sussr3/autoquack_foton_log_recent.log
Checking foton file to see if filters got implemented correctly
BAD - Filter SR3_M1_YAW_EST_MEAS_BP has issues in sect. 1 : DBL_notch
at least one filter got messed up, please follow up...
Autoquack process complete
initial foton call succeeded
foton file ready for updating
starting foton cleanup process
final foton call succeeded
log file updated
please review the recent foton -c log file at
/opt/rtcds/lho/h1/log/h1sussr3/autoquack_foton_log_recent.log
Checking foton file to see if filters got implemented correctly
BAD - Filter SR3_M1_YAW_EST_MODL_BP has issues in sect. 1 : DBL_notch
at least one filter got messed up, please follow up...
Autoquack process complete
>>
Check the foton file - it looks good - I checked the TFs by eye, and they look correct. the matlab error checker is irritated, but the matlab plots it makes look fine. I think it's OK.
Do a diff on the updated file and my backup - the only diffs I see are the new lines I added (that's good)
save the foton file, delete my backup.
press 'coef load' to get the new filters
(the CFC light goes green)
commit the updated foton file in userapps R31301
Save the work in the estimator folder
Estimator$ svn1.6 add fig*
A (bin) fig_2pcnt_error.png
A (bin) fig_2pcnt_error_result_EBblend.png
A (bin) fig_2pcnt_error_result.png
A (bin) fig_blend.png
A (bin) fig_perf1_gainerror.png
A (bin) fig_perf2_0p5freqerror.png
A (bin) fig_perf3_1p0freqerror.png
A (bin) fig_perf4_perfectmatch.png
$ svn1.6 add Estimator_blend_doublenotch_SR3yaw.m make_SR3_yaw_blend.m
A Estimator_blend_doublenotch_SR3yaw.m
A make_SR3_yaw_blend.m
committed in R12257
Set the model to a good state:
final switch = OFF.
gain of the normal yaw damping set back to -0.5
OSEM_Damper = populated, but off (in=off, out=off, gain=0)
Estim_Damper = populated, but off (in=off, out=off, gain=0)
OSEM bandpass = populated and set to running state (on, gain=1)
MODEM bandpass = populated and set to running state (on, gain=1)
accept SDF changes in H1:SUS-SR3_M1_
YAW_EST_MODL_BP
YAW_EST_OSEM_BP
YAW_DAMP_EST
YAW_DAMP_OSEM
save this to the safe file - I have not changed the observing file!
the SDF shows 0 differences
notes on Diff of foton file:
brian.lantz@cdsws44:/opt/rtcds/userapps/release/sus/h1/filterfiles$ diff H1SUSSR3.txt H1SUSSR3backup.txt
1025,1030d1024
< # DESIGN SR3_M1_YAW_EST_MEAS_BP 0 sos(0.00026333867650529759, [0.99999999999999867; 0; -0.9999616512111712; 0; -1.999953052714962; \
< # 0.99995343154104388; -1.9997062783494941; 0.99970796324744837; -1.9998957078482871; \
< # 0.99989686159668212; -1.9999090565491939; 0.99990984807473893; -1.9999426937932141; \
< # 0.99994346902553977; -1.9999108726927539; 0.99991163318180731; -1.9999774146135141; \
< # 0.99997744772231478; -1.9999375279667919; 0.99993768590749621; -1.999963134023643; \
< # 0.99996328560740799; -1.9999399837273171; 0.9999401295235868])
1032,1037d1025
< SR3_M1_YAW_EST_MEAS_BP 0 21 6 0 0 DBL_notch 2.633386765052975870236851e-04 -0.9999616512111712 0.0000000000000000 0.9999999999999987 0.0000000000000000
< -1.9997062783494941 0.9997079632474484 -1.9999530527149620 0.9999534315410439
< -1.9999090565491939 0.9999098480747389 -1.9998957078482871 0.9998968615966821
< -1.9999108726927539 0.9999116331818073 -1.9999426937932141 0.9999434690255398
< -1.9999375279667919 0.9999376859074962 -1.9999774146135141 0.9999774477223148
< -1.9999399837273171 0.9999401295235868 -1.9999631340236430 0.9999632856074080
1042,1047d1029
< # DESIGN SR3_M1_YAW_EST_MODL_BP 0 sos(0.99973666135688777, [-1.000000000000002; 0; -0.9999616512111712; 0; -1.999965862142562; \
< # 0.99996754725922932; -1.9997062783494941; 0.99970796324744837; -1.9999754834715859; \
< # 0.99997627502341802; -1.9999090565491939; 0.99990984807473893; -1.999975984305477; \
< # 0.99997674481928778; -1.9999108726927539; 0.99991163318180731; -1.9999871245769849; \
< # 0.99998728252160574; -1.9999375279667919; 0.99993768590749621; -1.9999876354434321; \
< # 0.99998778124317389; -1.9999399837273171; 0.9999401295235868])
1049,1054d1030
< SR3_M1_YAW_EST_MODL_BP 0 21 6 0 0 DBL_notch 9.997366613568877680151559e-01 -0.9999616512111712 0.0000000000000000 -1.0000000000000020 0.0000000000000000
< -1.9997062783494941 0.9997079632474484 -1.9999658621425620 0.9999675472592293
< -1.9999090565491939 0.9999098480747389 -1.9999754834715859 0.9999762750234180
< -1.9999108726927539 0.9999116331818073 -1.9999759843054770 0.9999767448192878
< -1.9999375279667919 0.9999376859074962 -1.9999871245769849 0.9999872825216057
< -1.9999399837273171 0.9999401295235868 -1.9999876354434321 0.9999877812431739
Edgard, Brian
We took a suite of measurements for SR3 similar the ones from 83940 with the intent of testing the OSEM estimator. We did not get quite that far, but we got data that will be useful to get a more accurate noise budget for the scheme.
The measurements were taken with the following settings
- The M1 DAMP filters were at a gain of -0.5, exchept for Yaw, which we reduced to a gain of -0.1. This is the preferred configuration to get the data for the Yaw estimator.
- The coil driver filters in state 1.
- The ISI state was ISOLATED, but HEPI is locked, so we circumvented guardian by sliding off the Isolation Gain on HEPI.
Two different sets of measurements were taken. The ISI to M1 measurements live in:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/SR3/Common/Data
and are named:
2025-04-18_1900_H1ISIHAM5_ST1_WhiteNoise_SR3SusPoint_{L,T,V,P,Y,R}_0p02to50Hz_estimator.xml
The M1 to M1 measurements live in:
/ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/SR3/SAGM1/Data
and are named
2025-04-18_2202_H1SUSSR3_M1_WhiteNoise_{L,T,V,P,Y,R}_0p01to50Hz.xml
All the changes were committed to the SVN as of revision 12258 (at the end of the day, after other work was committed too).
TITLE: 04/18 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
Vacuum team has been working hard to get the turbo pumps runnign today, and got the turbo pumps on around 23:30 or so.
I have put up an NDCOPE on NUC 23 of one of the vacuum pressure sensors on BSC8 so non-VAC people could watch the vacuum pressure go down over the weekend.
Randy & Mitchel did a run to pasco to getsme parts & got back from Pasco by 18:45 UTC
Overall it's been a quiet day.
LOG:
Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
---|---|---|---|---|---|---|
15:10 | VAC | Jordan | LVEA | N | Turning on roughing pumps | 19:10 |
15:42 | FAC | Kim | LVEA | N | Technical cleaning | 15:42 |
16:25 | EE | Fil & Marc | LVEA | N | Pulling cables | 19:25 |
19:31 | EE | Fil & Marc | LVEA | N | pulliung cables for HAM1 | 23:05 |
20:16 | Tour | Amber & Tour | Control Room & Overpass | N | Giving a tour to some local kids. | 19:46 |
20:32 | VAC | Jordan | LVEA | N | Vacuuming | 23:32 |
20:40 | SEI | Brian & Edgar | End Y & X | N | Takin a look at the End stations | 21:36 |
21:43 | SUS | Edgar | Control Rm | N | Taking TF on HAM5 | 23:43 |
FAMIS 26374
The Vibrometers for the HVAC fans look ok , no interesng feates really stand out.
Finished dressing and installing cables for the new feedthroughs on HAM1.
First we powered off the ISI interface and coil drivers for HAM1, disconnected all SEI cables from HAM1, redressed and reconnected them. Next we dressed all HAM1 RF cables and installed to feed throughs. We installed shrink tube to isolate the SMA connectors from each other.
All DSUB RM1, PM1, and ISC cables are reconnected.
There is a missing cable tray still to be dressed along the D6, D5, D4 side of HAM1. Cables are temporarily dressed in this area, awaiting tray installation. All SEI electronics remain off.
D. Sigg, F. Clara, M. Pirello
J. Kissel scribing for S. Koehlenbeck, J. Freed, and R. Short ECR E2400083 IIET 30642 WP 12453 Just writing a separate explicit aLOG for this for ease of reference in the future. Before, during and after the SPI install we measured power along respective paths, (1) The p-pol in-coming power into the whole ALS / SQZ / SPI pick-off path, (2) The "ALS COMM" path: p-pol power in transmission of the ALS-PBS01 with the newly modified ALS-HWP2 position to get more power total power in the paths (3) and (4), (3) The "SPI pick-off" path: The ~s-pol power in reflection of SPI-BS1, (4) The "ALS/SQZ Fiber Distribution" path: ~s-pol power in transmission of SPI-BS1, (see discussion in LHO:83978 as to why we're not so confident the reflection from ALS-PBS01 is entirely s-pol, which is why I say "~s-pol" here.) The BEFORE vs. AFTER power in these paths is as follows: Path Measured Between Raw Power [mW] PMC TRANS [W] Date/Time Measured Scaled Power [mW] Fractional Power [%] (1) ALS-L1 and ALS-HWP2 2060 103.2 2025-04-15 21:39 UTC 2095.9 --- % BEFORE (2) ALS-M2 and ALS-L2 1970 102.8 2025-04-15 22:17 UTC 2012.2 96% (4) ALS-M9 and ALS-FC2 48.7 103.0 2025-04-15 21:48 UTC 49.646 2% % AFTER (2) ALS-M2 and ALS-L2 1790 103.3 2025-04-17 21:13 UTC 1817.7 87% (3) SPI-L1 and SPI-L2 186 103.5 2025-04-16 22:43 UTC 188.7 9% (4) ALS-M9 and ALS-FC2 50.5 103.5 2025-04-16 22:43 UTC 51.232 2% where I've scaled all the raw power measurements by the rough nominal PMC TRANS power during recent observing times, 105 [W], i.e. (Scaled Power [mW]) = (Raw power) * (105 [W] / PMC TRANS [W]) and (Fractional Power [%]) = 100 * {Scaled Power [mW]; paths (2)-(4)} / {Scaled Power [mW]; path 1} As Ryan mentions in LHO:83989, for the purposes of safe long term storage, after all was said and done, we rotated SPI-HWP1 such that only 20 [mW] would go toward the SPI-FC1 fiber collimator, and it's dumped upstream just after SPI-L1. These AFTER power levels are what we anticipate running the rest of O4 in, with the SPI pick-off path safely out of commission. 2W Measurements Head: Ophir 10A-V2-SH SN122042 Readout: Ophir 20C-SH SN171175 Accuracy: +/-3% 200 mW Measurements: Head: Thorlabs S401C Readout: Thorlabs PM100-D Accuracy: +/- 7% The attached picture summarizes all this info. The picture was take midday 2025-04-17, so you see the Ophir power meter in the middle of the ALS COMM
Fri Apr 18 10:09:22 2025 INFO: Fill completed in 9min 18secs
I confirmed a good fill curbside.
J. Kissel scribe for S. Koehlenbeck, J. Freed, R. Short, and guest star J. Oberling ECR E2400083 IIET 30642 WP 12453 Toward the end of day two of install (LHO:83961), the team set the power at the input of the ALS-FC2 by rotating ALS-HWP2, to be 50.5 [mW] (with PMC TRANS at 103.5 [W]). The reported power for the on-table ThorLabs SM1PD1A, however, measured consistently lower at "31 [mW]," lower than the goal for this PD, a reported power of "45 [mw]" (LHO:83927), when the power of the beam between ALS-M9 and ALS-FC2 was physically measured at 48.7 [mW] (with PMC TRANS at 103.0). We think lower reported power on the PD is related to (1) The slight translation of the what-used-to-be ALS-L5 to ALS-M9 beam, because of the thickness of the SPI-BS1 that was inserted into that path, and (2) a change in the amount of s- and p- polarization in reflection of the ALS-PBS01 after rotating ALS-HWP2 to increase the power in the ALS/SQZ/SPI path, because the polarization state of the reflection of a PBS can be power dependent. To support (2), we measured the polarization today between ALS-M9 and ALS-FC2 with a temporary PBS and power meter. On 2025-04-17 at 19:02 UTC with PMC power at 103.7 [W], we measure s-pol = 49.7 [mW] p-pol = 1.8 [mW] (total = 49.7 + 1.8 = 51.5 [mW]) Regrettably, we did not measure this polarization state prior to changing anything. However, because we've *measured* equal total power at ALS-FC2 before vs. after, we're confident that at least the total power going into ALS-FC2 is the same. As such, we called in Jason to help couple the beam into ALS-FC2 using ALS-M9 and what alignment screws are on ALS-FC2 itself. Attached is the trend of that process, where we used the SPI distribution chassis PD in two forms: H1:ALS-C_FIBR_INTERNAL_DC_POWER never calibrated version, used to be 0.1 [cts] H1:ALS-C_FIBR_INTERNAL_DC_POWERMON version we'd been using, calibrated into [mW] In the end, we landed with the values of these channels at H1:ALS-C_FIBR_INTERNAL_DC_POWER 0.1 [cts] H1:ALS-C_FIBR_INTERNAL_DC_POWERMON 31.4 [mW] which matches our goals from LHO:83927. The team also adjusted the position of the SM1PD1A in transmission of ALS-M9 to account for (1). However, even after moving the PD out of maximum and back, they were not able to find any position where the PD readout exceeded H1:ALS-C_FIBR_EXTERNAL_DC_POWERMON 31.0 [mW] This why we expect that something more like (2) is going on. Though we looked through - E1300483 (doesn't list ALS-M9), - E1900246 (calls the optic ALS-M6, which is not for 1064 nm in E1300483), - E0900325 (isn't new enough to have this mirror), - Peter King's purchase orders circa 2019 (Req 122638553 for the fiber collimator parts, and Req 122583017 for the SM1PD1A parts) we couldn't find anything that was clearly and obviously the ALS-M9 optic, so we can't validate or reconstruction the reflectivity in each polarization to model the factor of 31 [mW] / 45 [mW] = 0.7x (or 30% drop) reported value change. In any event, this EXTERNAL PD channel will need to be recalibrated to better reflect the real power in this path. Also, when we re-start up anything that uses the output of the ALS / SQZ fiber distribution, it may need to be adjusted to account for the polarization change described in (2)
TITLE: 04/18 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: 0.17 μm/s
QUICK SUMMARY:
The Vacuum team had pumped down to about 2 .7 torr.
There is some effort to clean up staging areas and put some things back into storage.
Sounds like it will be a quiet day around here.
Roughing pumps are being turned back on to get us down to 1 torr so we can get the Turbo pumps running!
4-17 (Thursday) activities: - The corner pumpdown continued, we are at ~3 Torr now, today the pumping was on for 12 hours. The pumping speed is still at (~1900 l/min). Tomorrow 5-6 more hours are needed before switching on the turbos - A wide-range gauge (compatible with the supersucker cart) on a tee and along with a pumpdown port was installed on the freshly installed HAM6 turbo - The HAM6 turbo was then started up - as it was its initial test -, and keeps running, ready to be valved in tomorrow - The BSC8 annulus Ion pump is still suffering (~8E-6 Torr), but the pressure is slowly coming down - The HAM4 annulus system has been taken care of, after switching off the Ion pump last week, now the volume is being pumped with an aux cart - The GV5 annulus system is still being pumped by an aux cart, with the Ion pump switched off - The leak checking was continued, all the CF flanges on the Y-manifold were leak checked: Y+ side (6 pcs.); Turbo flange (1 pc.); vent valve (1 pc.); Varian valve (1 pc., see more info at aLog 83951 - after all, it seems that it is only an internal leak). All flanges were found leak-tight.
M. Todd, C. Compton, S. Dwyer
Over the past few weeks I've been trying to understand what we can learn from some of the ETMY ring heater power changes that we've made over the past 9 months or so. By looking at the Higher Order Mode spacing from OMC data as well as substrate lensing from the HWS data, we hope to be able to make some models or estimates of the coupling factors of the different actuators to substrate and surface defocus.
In particular, we want to use the HOM spacing to estimate how much of the surface defocus comes from self heating.
This derivation is better illustrated in the attachment below, which has a neater write up of the following logic:
1) Known values : HOM spacing, FSR, Cold-State Surface Curvature, Ring Heater Power, Coupling Factor of Ring Heater Power to Surface Defocus, g-factor of the ITM and ETM
2) Desired values: Surface Defocus from Self-heating (coupling * absorbed power)
Through solving some of the equations relating these values, with the assumption that our coupling factors are correct, we estimate the self-heating to change the surface curvature by about 13%.
TITLE: 04/17 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
The Vacuum team has been hard as work removing the air from the corner station. We seem to be below 20 torr.
The SPI team has Finished putting in their pickoff inside the PSL.
The SEI team workin on HAM1 still has more work to do.
SUS team has been cleaning optics in the Mega chamber as well
Also:
19:30 Hanford site called the LHO control room to let us know that they were performing a Take Cover Drill. The Operator Core decided to go over the protocol for shutting off the HVAC system in the case that this was not a drill.
LOG:
Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
---|---|---|---|---|---|---|
14:45 | FAC | Nellie & Kim | LVEA | NO | Technical Cleaning | 16:45 |
15:27 | VAC | Jordan | LVEA | N | Resuming pumpdown | 16:03 |
15:35 | FAC | Tyler | LVEA | N | Putting compass stickers on cranes | 16:47 |
15:44 | Plant Study | H Miss. cont | Mid X | N | Studying plants? | 17:11 |
15:47 | PCAL | Tony | PCAL | Yes | Transfer standard PCAL measurement | 15:57 |
15:58 | SEI | Jim | LVEA Racks | n | checking ADC cabling | 19:28 |
16:01 | FAC | Randy & Mitchel | LVEA | N | Moving equipment & machines Started ~16:09 | 18:35 |
16:10 | CDS | Dave B | Remote | N | Model & DAQ restart | 16:19 |
16:12 | SPI | Sina & Ryan S | LVEA | Yes | Installing SPI Pickoff | 19:16 |
16:13 | EE | Daniel | LVEA racks | N | Running Cabling | 21:01 |
16:14 | EE | Marc | LVEA | N | Running Cables with Daniel | 23:24 |
16:17 | SEI | Jim | LVEA HAM1 | N | Working on in air side feed throughs on HAM1 | 16:20 |
16:19 | SPI | Josh | Optics Lab & PSL | Yes | Working on Optics for SPI With Escort Jeff. | 19:16 |
16:48 | EE | Fil | LVEA | N | Cabling for HAM1 with Daniel & Marc | 23:24 |
17:02 | FAC | Kim | LVEA | n | Vacuuming in MSR | 17:32 |
17:04 | PSL | Jason | PSL | Yes | Helping out with SPI | 18:56 |
17:22 | SUS | Rahul & Ryan C | LVEA HAM6-7 | N | First contact of triple suspensions. | 18:14 |
18:09 | VAC | Janos & Jordan | HAM6 area | N | Checking Guages and Valves | 20:24 |
18:42 | Sun | Ryan C | Y arm | n | Taking a walk down Y arm. | 19:15 |
18:46 | HAM1 | Camilla | LVEA | N | Retreiving Parts. | 18:53 |
19:38 | OPS | Tony, Ibrahim, Ryan C, Oli, TJ, Ryan S, Eric | Mechanical Room | N | Hanford Radiation Emergency Drill Respons | 19:39 |
20:25 | VAC | Jordan | LVEA HAM4 | N | Setting up pump on HAM4 Annulus & Cap Inventory Checks | 22:28 |
20:39 | SPI | Ryan S, Sina, Josh | PSL | Yes | Installing SPI Pickoff | 22:00 |
20:54 | VAC | Travis & Janos | HAM4 Area | N | Vacuum pump activities | 21:59 |
21:02 | SUS | Rahul, Ryan C | LVEA HAM6 | N | cleaning Tripple SUS optics. | 22:14 |
21:07 | Saftey | Richard | LVEA | N | Safety checks | 21:24 |
21:29 | SEI | Jim | LVEA HAM1 | N | Restarting HAM 1 SEI Systems | 22:28 |
22:00 | Prop | Travis | End X &Y | N | Property inventory | 22:37 |
22:14 | SEI | Jim | CER | N | Checking SEI Config | 00:14 |
S. Koehlenbeck, J. Freed, J. Kissel, J. Oberling, R. Short
The SPI pick-off path installation on the H1 PSL table is now complete. The beam in the new SPI path has been reduced to 20mW and is currently being dumped with a razor dump between SPI-L1 and SPI-L2. Pictures attached reflect the final installation and layout, which will be be reflected in the updated as-built layout at a later date.
Associated entries: 83925, 83933, 83956, 83961, 83978, 83983 (and more to come)
ECR E2400083 IIET 30642 WP 12453 Here's Ryan's birdseye view labeled with all the components. For details of the components, see the SPI BOM, T2300363, exported from its google sheets to -v4 as of this entry.
Tagging EPO for photos.
83996 Power In ALS / SQZ / SPI Paths Post SPI Pick-off Install
S. Koehlenbeck, J. Freed, R. Short, J. Kissel
The mode matching of the PSL pick-off beam to the SPI fiber collimator has been implemented using two lenses. The target beam has a mode radius of 550 µm at a position 63.5 cm downstream from the SPI beamsplitter (SPI-BS).
The lens configuration that produced the closest match to the target mode used:
L1: Focal length = 100 mm
L2: Focal length = 60 mm
Attached is a beam profile fit performed using JaMMT on data acquired with a WinCamD of the beam after SPI-L2. The measured beam radii at various distances from the SPI-BS are as follows:
Distance (cm) | Horizontal Radius (µm) | Vertical Radius (µm) |
---|---|---|
70.734 | 476 | 542 |
91.054 | 470 | 543.5 |
116.454 | 558.5 | 616.5 |
Both lenses are oriented such that their planar sides face the small beam waist between the two lenses. The arrows on the lens mounts point toward the convex surfaces.
The power transmission through the fiber has been measured to be 83 %.
ECR E2400083 IIET 30642 WP 12453 Some "for the record" additional comments here: - Sina refers to the "SPI-BS" above, which is the same as what we've now officially dubbed as "SPI-BS1." - Lenses were identified to be needed after the initial measurement of the beam profile emanating from SPI-BS1. That initial beam profile measurement is cited in LHO:83956, and the lens also developed in JaMMT with the lenses that were available from the optics lab / PSL inventory. - If anyone's trying to recreate the model of the beam profile from the two measurements (LHO:83956 with no lenses, and the above LHO:83983) just note that the "zero" position is different in the quoted raw data; in LHO:83956 is the front of the rail, on Column 159 of the table, and in LHO:83983 the zero position is the SPI-BS1 reflective surface which is on Column 149 of the table, i.e. a 10 inch = 25.4 cm difference. - The real SPI-L1 installed to create this mode-shape / beam profile is labeled by its radius of curvature, which is R = 51.5 mm, and thus its focal length is more precisely f = R*2 = 103 mm. (We did find a lens that does have f = 60 mm for SPI-L2, and it's labeled by its focal length.) - "the fiber" is that which is intended for permanent use, depicted as SPI_PSL_001 in the SPI optical fiber routing diagram D2400110, a Narrow Key PM-980 Optical Fiber "patch cord" from Diamond, whose length is 30 [m]. This fiber will run all the way out to SUS-R2, eventually, to be connected as the input to the SPI Laser Prep Chassis (D2400156). - Per design, light going into this fiber is entirely p-pol, due to polarization via SPI-HWP1 and clean-up by SPI-PBS01 just upstream. We did not measure the polarization state of the light exiting the fiber. - The raw data that informs the statement that "the power transmission thru the fiber has been measured to be 83%": : We measured the input to the fiber coupler, SPI-FC1, via the S140C low-power power meter we'd been using throughout the install. The output power was measured via a fiber-coupled power meter Sina had brought with her from Stanford (dunno the make of that one). : We measured the power input to the fiber twice several hours apart (with the change in fiber input power controlled via the SPI-HWP1 / SPI-PBS01 combo)., (1) 19.9 [mW] with PMC TRANS power at 104.1 [W] at 2025-04-17 16:35 UTC (while the PMC power was in flux from enviromental controls turn on) (2) 180 [mW] with PMC TRANS power at 103.5 [W] at 2025-04-17 14:00 UTC (while the PMC power was quite stable) : We measured the output power (1') 16.6 [mW] with PMC TRANS power at 103.7 [W] at 2025-04-17 17:35 UTC (an hour later than (1)) (2') 150 [mW] with PMC TRANS power at 103.5 [W] at 2025-04-17 14:00 UTC (simultaneous to (2)) : Thus derive the transmission to be (1'') (16.6 / 19.9) * (104.1/103.7) = 0.837 = 83.7% and (2'') (150 / 180) * (103.5/103.5) = 0.833 = 83.3%
In the attachment you will find the JAMMT model for the measured beam profile of the PSL pick off with the origin a SPI-BS1, as well as the lenses used to adjust the mode of the beam for the fiber collimator FC60-SF-4-A6.2-03.
J. Kissel scribing for S. Koehlenbeck, R. Short, J. Oberling, and J. Freed ECR E2400083 IIET 30642 WP 12453 During yesterday's initial work installing the SPI pick-off path (LHO:83933), the first optic placed was SPI-BS1, the 80R/20T power beam-splitter that reflects most of the s-pol light towards the new SPI path. The pick-off is to eventually be sent into a SuK fiber collimator (60FC-SF-4-A6.2S-03), so we wanted to validate the beam profile / mode shape of this reflected beam. The without changing any power in the ALS/SQZ/SPI pick-off path, the power now reflected from newly installed SPI-BS1 measured ~40 [mW] (see LHO:83946). This is too much for the WinCam beam profiler, so they used ALS-HWP2 to rotate the polarization going into ALS-PBS01, and thus reduced the reflected s-pol light in this ALS/SQZ/SPI pick-off path to ~10 [mW]. That necessarily means there's a little more of the ~2 [W] p-pol light transmitted and going toward the HAM1 light pipe, so they placed a temporary beam dump after ALS-M2 so as to not have to think about it. The they set up a WinCam head on a rail and gathered the beam profile. With the WinCam analysis software on a computer stuck in the PSL, they simply gathered the profile information which I report here: # Distance[cm] Radius[um] Radius[um] X Y 0.0 680.5 717 17.78 465 504 25.4 389 428.5 30.48 346.5 368 38.1 281.5 300.5 where "X" is parallel to the table, and "Y" is orthogonal to the table. The "0.0" position in this measurement is the "front" of the rail (the right most position as pictured in the attachment), which is Column 159 of the PSL grid. SPI-BS1 has the center of its reflective surface is set in +/- X position in Column 149 (within the existing ALS-PBS01 to ALS-M9 beam line). It's +/- Y position is set to create a reflected beam line along Row 30 of the grid, and the WinCam head and rail are centered in +/- Y on that Row to capture that beam. Using this profile measurement, we find it to be quite different than expected from when this path was installed circa 2019 (see e.g. LHO:52381, LHO:52292, LHO:51610). Jason shared his mode matching solution from LHO:52292 with us prior to this week, and I've posted it as a comment to that aLOG, see LHO:83957. We think we can trace the issue down to an error in the as-build drawing for the PSL: - the whole beam path running in the +/-X direction from ALS-M1 to ALS-M2 is diagrammed to be on row 23 -- however, we find in reality, the path lies on row 25. That's 2 inches more between the (unlabeld) pick-off beam splitter just prior to ALS-M1 and ALS-M1 itself. Easily enough to distort a mode matching simulation. - Jason confirms that he used the *drawing* to design the lens telescope for this ALS/SQZ fiber distribution pick-off path. More on this as we work through a lens solution for the SPI path. As of this entry, we elect to NOT create a new solution for the whole ALS/SQZ fiber distribution pick-off i.e. we *won't* adjust ALS-L1 or ALS-L5 in order to fix the true problem. But, we report what we found in the event that a case is better made to help mode matching and aligning into the ALS/SQZ fiber distribution pick-off easier -- as we have verbal confirmation that it was quite a pain. For the record the fiber collimator used in the ALS/SQZ distribution pick-off is a Thor Labs F220 APC-1064.
Just a quick trend of the SM1PD1A EXTERNAL PD in transmission of ALS-M9 after they throttled the s-pol power in the ALS/SQZ/SPI path to ~10 [mW]. In that trend, you can see the different in "lights on" vs. "lights off" highlighted with the magenta vertical lines. Note, as you can see in the picture, the reflection of ALS-M9 is dumped so as to not have to think about how much power is or is not going into the ALS/SQZ fiber distribution collimator (ALS-FC2), so the INTERNAL monitor PD that's in the distribution chassis itself is "correctly" unexpectedly reading nothing, so I don't show it.
Correction to the last sentence of the main entry -- the ALS/SQZ fiber collimator is *not* an, but instead a Thorlabs Fiber Port PAF2-5A, pictured well in FinalInstall_ALSfiber.jpg from LHO:83989. I had incorrectly assumed that this collimator would be a copy of ALS-FC1, which *is* listed in E1300483 as an F220 APC-1064.
In the attachment you will find the fit with JAMMT to the measured beam profile data with offset correction:
Distance (cm) | Radius horiz. (um) | Radius vert. (um) |
17.46 | 680.5 | 717 |
35.24 | 465 | 504 |
42.86 | 389 | 428.5 |
47.94 | 346.5 | 368 |
55.56 | 281.5 | 300.5 |
Summary
Q: What is the relationship between the strength of violin mode ring-ups and the number of narrow spectral artifacts around the violin modes? Is there a clear cut-off at which the contamination begins?
A: The answer depends on the time period analyzed. There was an unusual time period spanning from mid-June 2023 through (very approximately) August 2023. During this time period, the number lines during ring-ups was much greater than in the rest of O4, and the appearance of the contamination may have begun at lower violin mode amplitudes.
What to keep in mind when looking at the plots.
1. These plots use the Fscan line count in a 200-Hz band around each violin mode region, which is a pretty rough metric, and not good for picking up small variations in the line count. It's the best we've got at the moment, and it can show big-picture changes. But on some days, contamination is present, but only in the form of ~10 narrow lines symmetrically arranged around a high violin mode peak. (Example in the last figure, fig 7) This small jump in the line count may not show up above the usual fluctuations. However, in aggregate (over all of O4) this phenomenon does become an issue for CW data quality. These "slight contamination" cases are also particularly important for answering the question "at what violin mode amplitude does the contamination just start to emerge?" In short, we shouldn't put too much faith in this method for locating a cut-off problematic violin mode height.
2. The violin modes may not be the only factor in play, so we shouldn't necessarily expect a very clear trend. For example, consider alog 79825 . This alog showed that at least some of the contamination lines are violin mode + calibration line intermodulations. Some of them (the weaker ones) disappeared below the rest of the noise when the violin mode amplitude decreased. Others (the stronger ones) remained visible at reduced amplitude. Both clusters vanished when the temporary calibration lines were off. If we asked the question "How high do the violin modes need to be...?" using just these two clusters, we'd get different apparent answers depending on (a) which cluster we chose to track (weak or strong), and (b) which time period we selected (calibration lines on or off). This is because at least some of the contamination is dependent on the presence & strength of a second line, not a violin mode.
Looking at the data
First, let's take a look at a simple scatter plot of the violin mode height vs the number of lines identified. This is figure 1. It's essentially an updated version of the scatter plots in alog 71501. It looks like there's a change around 1e-39 on the horizontal axis (which corresponds to peak violin mode height).
However, when we add color-coding by date (figure 2), new features can be seen. There's a shift at the left side of the plot, and an unusual group of high-line-count points in early O4.
The shift at the left side of the plot is likely due to an unrelated data quality issue: combs in the band of interest. In particular, the 9.5 Hz comb, which was identified and removed mid O4, contributes to the line count. Once we subtract out the number of lines which were identified as being part of a comb, this shift disappears (figure 3).
With the distracting factor of comb counts removed, we still need to understand the high-line-count time period. This is more interesting. I've broken the data down into three epochs: start of O4 - June 21, 2023 (figure 4); June 21, 2023 - Sept 1 2023 (figure 5); and Sept 1 2023 - present (figure 6). As shown in the plots, the middle epoch seems notably different from the others.
These dates are highly approximate. The violin mode ring-ups are intermittent, so it's not possible to pinpoint the changes sharply. The Sept 1 date is just the month boundary that seemed to best differentiate between the unusual time period and the rest of O4. The June 21 date is somewhat less arbitrary; it's the date on which the input power was brought back to 60W (alog 70648), which seems a bit suspicious. Note that, with this data set, I can't actually differentiate between a change on June 21 and a change (say) on June 15th, so please don't be misled by the specificity of the selected boundary.
Kiet, Sheila
We recently started looking into the whether nonlinearity of the ADC can contribute to this by looking at the ADC range that we were using in O4a.
They are showed in the H1:OMC-DCPD_A_WINDOW_{MAX,MIN} that sum the 4 DC photodiodes (DCPD). They are 18 bits DCPD, so that channel should saturate at 4* 2^17 ~520,000 counts.
Now there are instances that agree with Ansel report when there are violin mode ring up that we can see a shift in the count baseline.
Jun 29 - Jun 30, 2023 when the baseline seems to shift up and stay there for >1 months, Detchar summary page show significant higher violin mode ring up in the usual 500-520Hz region as well as the nearby region (480-500 Hz)
Oct 9, 2023 is when the temporary calibration lines are turned off 72096, the down shift happened right after the lines are off (after 16:40 UTC)
During this period, we were using a~5% of the ADC range (difference between max and min channel divided by the total range - 500,000 to 500,000 counts), and it went down to ~2.5 % once the shift happenned on Oct 9, 2023. We want to do something similar with Livingston, using the L1:IOP-LSC0_SAT_CHECK_DCPD_{A,B}_{MAX,MIN} channels to see the ADC range and the typical count values of those channels.
Another thing for us to maybe take a closer look is the baseline count value increase around May 03 2023. There was a change to the DCPC total photocurrent during that time (69358). Maybe worth checking if there is violin mode contaimination during the period before that.
Kiet, Sheila
More updates related to the ADC range investigation:
Further points + investigations:
Kiet, Sheila
Following up on the investigation into potential intermixing between higher-order violin modes down to the ~500 Hz region:
The Fscan team compiled a detailed summary of the daily maximum peak height (log10 of peak height above noise in the first violin mode region) for the violin modes near 500 Hz (v1) and 1000 Hz (v2). They also tracked line counts in the corresponding frequency bands: 400–600 Hz for v1 and 900–1000 Hz for v2. This data is available in the Google spreadsheet (LIGO credentials required).
n1_height
and n2_height
are the max peak heights of v1 and v2, and n1_count
and n2_count
are the corresponding line counts. There appears to be a threshold in violin mode amplitude beyond which line counts increase (based on {n1_height, n2_height} vs. {n1_count, n2_count} trends).Next: We plan to further investigate the lines that appear when both modes are high, the goal is to identify possible intermodulation products using the recorded peak frequencies of the violin modes.