Need model restart in week of Jan 5th to correct JAC/IMC models

Jennie W, Dave B,

 

Jeff and I put in a bypass in the h1ascimc model (see alog #88465) so we could put in the simulink infrastructure to switch between using the PSL periscope PZT as part of the IMC control or as part of the JAC control.

At the moment the switch 'H1:ASC-IMCJAC_PZTOUTSW' is set to ON which should let the IMC servo use the PZT.

However the logic I put in will not switch the feedback to take inputs from the JAC servo if I turn the switch off.

This is because Choice 2 and 3 in the picture are set to pass their first input if the switch output is '>= 0', so whichever state it is in the IMC PZT output will be sent to the DAC.

I have changed these choices to >0 so that the top input (IMC PZT output signal) will be sent to the DAC if the switch is 1 and the bottom input (JAC PZT output signal) will be sent to the periscope otherwise.

I committed the changed /opt/rtcds/userapps/release/asc/h1/models/h1ascimc.mdl to the svn.

HAM7 alignment progress

Kar Meng, Sheila

I walked FC1 back to it's original slider position 88602 while walking the two steering mirrors between the OPO and SFI1 to keep the beam transmitted towards ZM4. Once this was done the beam was hitting the beam dump meant to catch the reflection off the beam diverter from the IFO.  I touched the last mirror on the VIP, B:M4, to bring the beam towards the center on the iris in front of ZM4, and then Kar Meng was able to see a beam on the SQZT7 periscope.  

Before we started: ZM4: P -338.7 Y -1297.7 ZM5: -120 P -460 Yaw  We moved ZM4 +5 to get the transmitted beam onto the OPO IR PD, ZM4 -338 P -1297.7 Y, ZM5 -720 P 839 Y.  Then we were able to align the CLF to the cavity a bit better by watching the flashes on the scope.  We can see evidence of clipping as the ZMs drift in the purge air the transmitted power fluctuates,  

We adjusted the in chamber CLF refl steering mirror to center on the CLF top periscope mirror, and Kar Meng aligned the CLF refl shutter PD using mirrors on SQZT7.  We were able to see that the OPO was semi-locked on the dither lock, but this wasn't stable. 

FARO Survey of WBCS3 and Partial WBSC2 Support Tube Ends

R. Crouch, J. Oberling

Yesterday we began measuring the locations of the vacuum chamber support tube ends using the FARO laser tracker.  We started with the support tubes for the WBSC3 chamber and the +X ends of the WBSC2 support tubes as these were the most readily accesible.  The remaining support tubes in the LVEA (WBSC1, WBSC2 -X ends, and all WHAM chambers except WHAM7) have iLIGO-era PEM Interface Plates on them that block the support tube; some of these plates have undocumented spacers between them and the support tubes they are attached to, meaning we cannot accurately locate the support tube end w.r.t. the PEM interface plate and therefore making an accurate measurement of the support tube location impossible.  As an aside, Jim is in the process of removing these plates from the chambers (so far WHAM3 and WHAM4 are complete, WHAM1 and WHAM2 are 75% complete), so we can get at these support tube ends as the opportunity arises (he will then reinstall these plates, as they make for very convient mounts for dial indicators).

Measurement Method

This is a fairly straightforward measurement, but there is a somewhat subtle "gotcha" that needs to be accounted for to get an accurate measurement.  But first things first, we aligned the FARO to the LVEA's Building Coordinate system using our red alignment nests, then applied the X and Y axis rotations required to align the FARO to the site global coordinate system (see T0900340 for a brief overview of the coordinate systems in use).  We then loaded CAD models of the support tubes, that Ryan downloaded from the SolidWorks vault with each model in the site global coordinate system, into the FARO's control software, PolyWorks.  PolyWorks automatically reads the coordinate system information contained in the CAD files and places these models in position w.r.t. to the site global coordinate system.  This gives us nominal locations of the support tube ends, a guide for our measurements, and also a nice visual reference for where everything is positioned.

Now for the "gotcha."  The physical support tubes have a hole in the center of each end that is not represented in the CAD model, and this hole is large enough that the FARO target (a Spherically Mounted Retroreflector, or SMR, with a 1.5" diameter) sits slightly inside the hole.  This means that when you're taking a measurement of the center of the support tube end using this hole the SMR is not measuring the location of the actual support tube end, it is a few mm inside of it.  To account for this we did the following:

1. Use the SMR to get the coordinate corresponding the the axial length of the support tube on either side of the end and calculate the average (to remove any yaw in the support tube)
   • Using WBSC3 as an example, the support tubes lie parallel to the y-axis.  So we touch the SMR to either side of the support tube and record the y-axis coordinate, then calculate the average
   • We do this for each individual support tube end, as each one is slightly different
2. Use the SMR to get the same coordinate, but this time with the SMR sitting in the center of hole of the support tube
3. Calculate the difference between the two, to get the offset required for an accurate measurement
4. In the PolyWorks software:
   • Use the CAD model to create points representing the center of each end of the support tube
   • Create a line between each end point, representing the theoretical centerline of the support tube
   • Create a Measurement Point by offsetting the support tube end point along the centerline and to the inside of the support tube by the amount calculated in steps 1-3
5. Congratulations, you now have a measurement point that represents the nominal location of the support tube end, taking into account the offset required due to SMR positioning inside the center hole

To take the measurement we used the Build/Inspect mode in PolyWorks.  In this mode we have to be sure to select the "Towards Object" compensation method, which automatically compensates for the radius of the SMR (3/4", or 19.05 mm).  If "None" is selected the FARO measures to the center of the SMR, but our measurement point is at the edge of the SMR, since that's what is physically touching the support tube, so we need to compensate for that radius.  This gives us the deviations of the measurement point, which can then applied to the point representing the center of each support tube end to give their measured location.  The results of our measurements are shown in the attachment.  Since we had measurements for each end of the WBSC3 support tubes I also added a distance feature representing the measured length of each WBSC3 support tube.

Wrapping Up

Some points for discussion/further thought.  Keep in mind that the BSC support tubes are not exact representations of where their respective optics are; we only aligned the optic during aLIGO install, and in the end didn't really care where the support tubes ended up as long as HEPI had enough range to work.  This means that any deviation from nominal seen in the support tube ends is not an indication of misalignment of that chamber's optic.

1. The WBSC2 support tubes were supposed to be lowered by ~2.5 mm to account for the BS z-axis position being at -82.9 mm instead of -80.0 mm; this was done because, while the 4km arm cavities are flat in global coordinates the IFO input and output arms are not, so the BS had to be lowered to properly direct the beam (which rises in elevation while traversing the PRC) into the arms.  Therefore our expectation is that the WBSC2 support tubes are below the nominal z-axis coordinate of 1130.3 mm (we recently discovered that this change was not accounted for in the SolidWorks models for the sites).  While the global z-axis coordinate for all BSC support tubes is 1130.3 mm, if WBSC2 was lowered as required we would still expect to see a z-axis deviation in the measured points, but this is clearly not the case.
   • I was at LLO working on PRC alignment when the WBSC2 in-chamber alignment was started, so I have no memory of the initial positioning of the BS in-chamber; this was done by Hugh Radkins and Doug Cook (I had returned in time for pitch/yaw alignment).  Looking back at their notes they had to move HEPI +X by 4.6 mm, -Y by 2.3 mm, and +Z by 0.4 mm to position the BS, so this does not fully account for apparent lack of support tube lowering.  But as stated above, this does not necessarily mean the BS is too high (we'll know that for sure when we measure it once WBSC2 is opened in March 2026).
2. The measured length for the WBSC3 support tubes is shorter than their as-designed length of 3657.6 mm.  Not sure why at this point.
   • Once we get more full BSC support tube measurements we'll have more info to work from
3. The WBSC3 +X/-Y support tube end is a decent bit further in the +Y axis than expected.  Again, not sure why.
   • Looking back at my notes from install we had to move WBSC3 HEPI in the +Y dircection to properly place ITMx, so the overal deviation direction of these support tubes isn't a surprise.

This work was associated with LHO WP 12947, which also included the WBSC1 +X support tube ends.  Those support tubes still have PEM interface plates installed, so we are currently unable to measure them (will do in the future once the plates are removed).  Since we completed the rest of the measurements involved, I've closed the WP.

HAM1/2 beam positions with 2W (Betsy, Keita)

For the upcoming ISS array swap, we plan to bypass the IMC, which is known to be a pain, but we need a stable beam for the array alignment.

Once the corner volume is vent, we use the QPD on the old array and IMC-IM4_TRANS as the initial reference for bypassing the IMC. Once IMC is bypassed, we will center REFL WFS BEFORE removing the old array and record the RM1/RM2 PIT and YAW. This way, even if we somehow suspect e.g. the pointing of the beam going to the IM4 moved after removing the old array, we can still restore the pointing by looking at the REFL WFSs in addition to IM4.

We measured the beam positions on these QPDs today even though we'll repeat this later.

IFO configuration:

• IMC was locked with 2W.
• REFL beam diverter was closed so no light comes out. (POP bdv was also closed just because.) 
• The cover on the REFL septum window was removed.
• PRM, all IMs and RMs are aligned. (Watchdog of RMs were reset.) ITMs are misaligned.

Arrow ("->") means before and after the REFL centering servo (DC1 and DC2) was turned ON:

	PSL-ISS_SECONDLOOP_QPD	IMC-IM4_TRANS	ASC-REFL_A_DC	ASC-REFL_B_DC	SUS-RM1-M1_DAMP INMON	SUS-RM1-M1_DAMP INMON
PIT	-0.814	0.366	-0.884 -> 0	-0.995 -> 0	293 -> 168	-363 -> 68
YAW	0.655	-0.146	0.590 -> 0	0.220 -> 0	-176 -> -214	277 -> -70

Septum cover is left OFF but the PSL light pipe was closed after this. REFL centering was turned off but I didn't bother to offload the ASC output to RM sliders.

REFL WFS nubmers as of now are not super meaningful as we'll still have to lock HAM2 down, which potentially change the relative alignment between HAM1 and HAM2. (But it's good that the beam is still hitting REFL WFSs after HAM1 was locked down even though Jim noted that the ISI position of HAM1 is not good. )

I'll open the light pipe tomorrow and quickly repeat the measurement after Jim locks down HAM2 HEPI.

psams ramped off for HAM7 vent

Sheila, Filiberto

In prep for HAM7 vent, we ramped off the psams servo and the requested voltage.  This is different since the addition of the psams servo, screenshot shows how to get to the screens to ramp that off. 

first turned off the servo input, then ramp it's gain from 1 to 0 with 30 second ramp.  Then with 100 second ramp turned off the offset for the requested voltage.  This needs to be done for ZM4,5,2. 

We also set the guardians to down in prep for loosing high votlage to the OPO, SHG and PMC. 

We didn't do the pico controllers yet since Marc and Daniel are debugging them. 

ISI CPS Noise Spectra Check Weekly FAMIS

Closes FAMIS#27534, last checked 87787

I was supposed to do this last week but I was out, so doing it now. Last time it was done was 10/28, so this is comparing to measurements from two weeks ago.

Nothing of note, everything looks very similar to how it looked a couple weeks ago.

Workstations updated

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

Weekly In-Lock SUS Charge Measurement - FAMIS 28430

Attached are the plots for all four Test Masses.  Closing FAMIS 28430.

MY PT243B alarms bypassed, gauge is attempting to fire back up.

Bypass will expire:
Thu Nov  6 11:13:32 AM PST 2025
For channel(s):
    H0:VAC-MY_Y1_PT243B_PRESS_TORR
 

OPS Monday EVE shift summary

TITLE: 11/04 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Aligning
INCOMING OPERATOR: Oli
SHIFT SUMMARY: One lockloss, we are relocking at MAX_POWER.
LOG:                                                                                                                                                                                                                                                                                                                                                            

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
23:50	CAL	Tony	PCAL lab	LOCAL	Prep for end station meas tomorrow	00:35
00:49	CAL	Rick	Receiving	N	Pick up PSL parts	01:25
00:52	OPS	Ryan	Optics lab	N	Check on dust monitor	00:58

03:45 UTC Something started to ring up in the DCPDs and the 500Hz line looked large on DARM. None of the vioins were ringing up though, I eventually found that both ETMY and ETMX (mostly ETMX) mode1/6's drive was ringing up and once I turned off the damping the DCPDs came back down and so did the line on DARM. (tagging SUS). I then put the nominal gain back into ETMX mode6 and it started to damp back down.

04:03 UTC We dropped observing, I brought us to Hi gain ASC as a semi large earthquake from Eastern Russia was hitting us (6.0)

04:19 UTC lockloss from the Earthquake

04:55 UTC MC2 M3 tripped as the IMC was trying to relock after a lockloss from FIND_IR, a look at some of the OSEMs

04:56 UTC IA, after INPUT_ALIGN it took the IMC 6 minutes to relock itself

Explosions from east side of Yakima Training Center coupling strongly to DARM by exciting EX cryobaffle

Robert, Tony

My beating shaker data from Thursday commissioning was ruined by large scattering glitches in DARM. We also saw these glitches on Friday. I found that they were coincident with brief seismic and microphone signals (Figure 1). The coupling site has to be EX because the signals appear in DARM before they reach any other station (Figure 2). I was able to determine that they could be coming from the direction of one crater-marked site on the east side of YTC, but not a more central location that Tony and I had found. The propagation velocity of the 5-20Hz signal is the same for both seismic and acoustic sensors and about 337 m/s indicating that the dominant propagation is through the air not the ground, though it couples to the ground locally. The linear attenuation in the ground at these frequencies is much greater than it is in the air.

The scattering noise produced at EX in DARM has harmonics of about 10 Hz (Figure 1, page 2). This is about the frequency of one of the worst resonances of the cryobaffles (9.7 Hz here: 56857 ). This is a reminder that we did not reduce the light reflected back into the interferometer from the cryobaffles, we just reduced their usual velocity by damping them. The explosions apparently kick the EX one pretty hard. It would be interesting if Detchar could keep track of the YTC glitches and also see if they ever knock us out of lock.

01:29 UTC lockloss

01:29 UTC lockloss, there was a wiggle in PR_GAIN right before the LL. Lockloss tool looks to be offline for the last hour.

ADC failure on seismic front end at EY

front end server h1seiey went down at 13:05 with an ADC timeout on the last ADC.  Restart of the server did not bring the ADC back.  Dave is headed out with a replacement.

This could be the cause of the last lockloss.

Getting un-stuck from having lost lock during OMC whitening change

[Jennie, Elenna, Oli, Keita, MattT, Jenne]

One of our locklosses this afternoon happens to have been while the OMC DCPD whitening was switching (reason is under separate investigation).  It happens that the gains we use for these now are the A0 and B0 gains, in filter banks on the IOPOMC0 model, not the OMC model.  The IOPOMC0 model is not part of the SDF revert process (probably because we never thought to add it in?).  This means that upon relock, the OMC guardian was confused when it was asked to do the SET_WHITENING state and it found that the gains were 0 or 2, not 1 and 1.  

The OMC guardian's DOWN state had an old comment (from before the omc0 days) where we explicitly set DCPD_A_GAIN and DCPD_B_GAIN both to 1, in case we lose lock during a whitening switch. For now (and in case we decide we don't want to add IOPOMC0 to the sdf revert list) I've added lines to also set DCPD_A0_GAIN and DCPD_B0_GAIN both to 1.  Hopefully we won't get stuck on this small little piece again, and can get back to figuring out our bigger locking issues.

Update on the search for the site of non-linear vibration coupling in the LVEA

Summary

I found vibration coupling associated with motion of the HAM4 ISI (at a few times background),  BSC2 ST2 motion (at about 10 times background), and, likely, on the chamber walls of the ITMs (accounting for much of DARM in the 20 Hz region). The coupling associated with HAM4 may be due to reflection of the 45 degree annular beams from the BS and its cage, and may be mitigated by BBS installation and table baffles at HAM4. The coupling at the chamber walls of the ITMs may be due to the 20 degree annular beam from the ITM bevels, which would be mitigated by installation of cage baffles on the ITMs. However,  I would like some more commissionsing time to be more sure of this.

Recently, broad-band non-linear vibration coupling in the corner station was revealed by investigations of the coupling of HVAC components to DARM (86412). This is an update on searches for the site of that coupling. 

We check for sites on the internal tables (ISIs) by shaking individual ISIs or HPIs. Discriminating between sites on the vacuum enclosure is more difficult because shaking at one location tends to shake many vacuum chambers about the same amount. To identify an enclosure site, we use frequency dependance and  propagation delays (velocities on these steel membranes are only 100s of m/s). The basic idea is that if a patch of chamber wall is producing noise by reflecting scattered light back into the interferometer, then an accelerometer that is placed on the outside of that patch will, comapared to other accelerometers, produce a signal that is  precisely correlated with the signal in DARM.

Internal tables

I eliminated most of the tables in the LVEA either by injecting into the ISI control loops or by monitoring their motion during external injections. However, I did find coupling at the HAM4 ISI and the BS ISI.

Coupling at HAM4 ISI

Figure 1 shows that we found coupling at the HAM4 ISI. An increase in Y-axis motion of about 30 produced a feature in DARM that was several times background. This coupling appeared mainly linear and so was not the coupling we were looking for. A potential source of this coupling is reflection of the 45 degree annular beam from the beamsplitter that illuminates this table (83050). The BBS, its less reflective cage and planned table baffling may mitigate this coupling.

Coupling with motion of ST2 of the BS ISI

Figure 2 shows that I produced noise in DARM by shaking the BS ISI.  I did a series of injections that suggest that noise in DARM is produced by motion of BS ISI ST2 (where the cage is attached), but not motion of ST0  (where the eliptical baffles are attached) or of the BS itself.  This noise may be associated with the 45 degree annular beam from the BS (83050) and may be reduced with the new BBS cage, which is less reflective.

Vacuum enclosure

I have been using three techniques to find coupling sites on the inside walls of the vacuum enclosure. These tests, while ongoing, have narrowed down the non-linear coupling to the enclosure walls in the vertex.

1) Shaker and speaker sweeps from multiple locations

Shaker sweeps are used in two ways. First, frequency consistency - if an accelerometer is mounted at the coupling site, and shows a resonance at some frequency, then there should be an indication of greater motion in DARM at that frequency also. Second, consistency for vibration injections from multiple locations. Thus if the accelerometer is mounted at the coupling site, and it moves less for injections onto the mode cleaner tube than onto BSC8, then DARM should also be less affected by the SR tube injection. Figure 3 illustrates this for one of the sweep pairs.

The most consistent accelerometer locations in frequency:  ITMX, ITMY and BS chamber walls

The most consistent accelerometer locations in response to different shaker locations: ITMX, ITMY and BS chamber walls

2) Beating shakers technique

The Beating Shaker technique (52184) uses differences in propagation time from different shaker locations to locate the coupling site. When two shakers inject at two slightly different frequencies (e.g. 35.005 Hz and 35 Hz), the beat envelope will have a different phase at different locations due to propagation delays. If the accelerometer is at the coupling site, its beat enveope will be in phase with DARM’s for any shaking location.

The beat envelope in DARM was not as clear as it has been for past uses of the Beating Shaker technique, because of the side bands. So I fit a simulated beat envelope using a cross correlation technique. This is illustrated in Figure 4.  The best accelerometers for beat consistency were ITMY–Y, ITMY-X and ITMX-Z. I think it might be useful for DetChar or others to search for an ASC motion that could account for the side bands during the injection period shown in Figure 4.

3) Hand held mini-shaker

A small shaker made of a speaker with an attached reaction mass (Figure 5) is used to take advantage of the large amplitude near-field region right at the shaker in an attempt to find a region on the vacuum enclosure where the shaker coupling dramatically increases. This technique eliminated the BSC7 potential sites and I hope to use it to test the 20 degree ITM  beam hypothesis in future commissioning sessions.

 

Since our accelerometer array has low spatial resolution (something to think about for CE) we also mount temporary accelerometers as we narrow in on a site. This is the stage I am at, mounting accelerometers to further narrow the site. However, the results so far are consistent with coupling of the 20 degree beam from the ITM bevels (83050) . These annular beams were elimited by the cage baffles at LLO and we plan on installing them at LHO.

 

Impulses on ETMY before lockloss last night

Looking back at this alog #87678 from Ibrahim, I looked at the lockloss tool for this time and could see the 1Hz growing oscillation on DHARD_P but also three impulse/glitchy things on ETMY drive and showing up in DARM1 loop.

Ops Eve Shift Summary

TITLE: 10/21 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: TJ
SHIFT SUMMARY: H1 was locked for most of my shift until the microseism eventually got too high. After that, I started troubleshooting issues with initial alignment that were eventually tracked down to be related to a commissioning change earlier in the day; TJ will have an alog with more on this. H1 is currently relocking up to DRMI.
LOG:

• 00:00 - Dropped observing from SQZ PMC unlocking
  • Guardians brought everything back automatically
  • Reapplied nominal damping gain for ETMX mode 1
• 00:05 - Observing
• 01:29 - Turned off ETMX mode 1 damping since monitor filter was ringing up again (see alog87585 for when this happened earlier today)
• 02:29 - Dropped observing to troubleshoot SQZ - alog87594
• 02:43 - Repplied nominal damping gain for ETMX mode 6 (it did not ring up again)
• 03:09 - Observing
• 03:22 - S251021u
• 04:27 - Lockloss - alog87595
  • Troubleshooting begins (see TJ's alog)

PSL Rotation Stage Calibration

J. Oberling, R. Short

After the PSL pump diode operating current increase earlier this morning, we performed a rotation stage calibration.  The curve is attached, as well as the SDF update.  New parameters:

• Power in
  • Old: 70.0
  • New: 71.7781
• Parameter B
  • Old: -24.79
  • New: -24.8263
• All other parameters unchanged.