A slow motion video of the fast shutter, firing with the high voltage driver in air, is here: slow motion video
Thu Aug 01 08:07:40 2024 INFO: Fill completed in 7min 36secs
TITLE: 08/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 1mph Gusts, 0mph 5min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.05 μm/s
QUICK SUMMARY:
Today we'll be closing upu HAM6!
Dust monitor 6 needs a restart, dm5 is reporting low battery on the medm which I haven't seen before. I also thought I left dm5 off as it was a noisy pumped dm, I'll take a quick look.
After transition to laser safe, I unlocked HAM6 ISI, did a small balance adjustment and ran some close out tfs. TFs look okay. I think SEI is ready for doors to go on.
TITLE: 07/31 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
SHIFT SUMMARY:
I know that there have been a lot of Laser trasitions done today...
But
The LVEA IS currently in LASER SAFE.
OFI work has continued all day :
Before closeout
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 17:22 | SAF | Laser HAZARD | LVEA | YES | LVEA is Laser HAZARD | 20:01 |
| 14:32 | FAC | Eric | FTCE | No | Working on Air Handler | 14:52 |
| 15:03 | FAC | Kim & Karen | LVEA | LASER Hazard | Technical Cleaning Kim out first | 15:53 |
| 15:16 | VAC | Gerardo | LVEA | yes | Dew Point measurements. | 15:26 |
| 15:29 | OFI | Sheila & Betsy | LVEA | Yes | Isolation ratio measurements, Betsy out first | 19:30 |
| 15:49 | PCAL | Francisco | PCAL Lab | Yes | PCAL PS45 measurement | 16:49 |
| 15:55 | OFI | Camilla, Keita | Optics lab & LVEA | Yes | Getting parts and helping the HAM5,6 crew | 19:16 |
| 16:10 | PEM | Robert, Milly, Carlos | End X | N | Testing PEM equipment | 20:01 |
| 16:18 | FAC | Karen | Mid Y | N | Dropping off supplies/ technical cleaning. | 17:04 |
| 17:04 | EE | Fil & Richard | LVEA | Yes | Checking on HAM5 | 17:04 |
| 17:47 | VAC | Gerardo | Relay tube | Yes | Relay tube valve open | 17:48 |
| 18:52 | EPO | Amber +10 | Ctrl Rm & Overpass | n | Tour | 18:52 |
| 19:29 | SAF | Oli & Ibrihim | LVEA | Yes | LASER Transition to safe. | 19:54 |
| 20:01 | OFI | Rahul & Betsy | LVEA | No | SUS OFI work, Rahul out first | 00:19 |
| 20:23 | VAC | Gerardo | LVEA | No | Isolating HAM7 | 21:03 |
| 20:28 | Staff Tour | Jenne + 15 | LVEA | No | Checking out the HAM5 & 6 Chamber. | 21:12 |
| 21:29 | PCAL | Francisco | PCAL Lab | yes | Checking Config | 21:39 |
| 21:59 | SAFE | Sheila | LVEA | Yes | LASER HAZARD Transition | 22:26 |
| 22:06 | OFI | Camilla | LVEA | Yes | Working on OFI with Sheila | 23:45 |
| 22:49 | SAFE | Ryan C. | LVEA | Yes | Laser Transition | 23:19 |
| 23:19 | VAC | Janos | HAM8 | N | Checking Vacuum system | 23:59 |
| 23:36 | SEI | Jim | HAM5 | N | Seismic system checks | 01:36 |
| 23:44 | SAF | LAZER SAFE | LVEA | YES | THE LVEA IS LASER SAFE :) | 22:24 |
| 23:48 | OFI | Richard | LVEA | N | Checking on the Status of OFI crew | 00:48 |
Ryan Crouch has Transitioned the LVEA to LASER SAFE.
Betsy, Rahul
This afternoon, Betsy adjusted the SD magnet on the OFI and we confirmed that it is sitting correctly in it's place. Next, she inserted the AOSEM and centered it on the magnet (polarity was already checked). We also took this opportunity to take the OLC/offsets/gain for the SD aosem, which is given below,
OLC = 17000, offsets = -8500, Gain = 1.739 (30,000/OLC). This has accepted in the SDF.
The in-air transfer function measurement results are attached below (we took only 3 averages) and they look healthy for all three dof - template at /ligo/svncommon/SusSVN/sus/trunk/OFIS/H1/OFI/SAGM1/Data
We then started attaching the OFI shroud as per D11800103 - the top two, side (+X side) and front shroud has been attached. Mitchell joined us to help with attaching the top and one of the shrouds. There are two/three more panels left to be attached, which will be done once Sheila is done with the beam alignment check.
I also took out an iris (and post holder) which was sitting in front of the OFI on the ISI table.
Sheila has Transitioned the LVEA to LASER Hazard.
Sheila, Betsy, Keita, Camilla. Continuing from 79373. Measured in 2021 in the lab in 59410.
Betsy and Sheila set up of the power meter in location B of 79373 with the wave-plate rotated such that the beam is visible. Distance between OM1 and retro-mirror is ~350mm, before the fast shutter.
The retro-refection wasn't perfect. Betsy and Sheila found that the HAM5 iris centered on the forward aux laser isn't well centered on the beam retro-reflected from the mirror in HAM6. This made it hard to block the ghost beam (direct reflection, no change in polarization) without also blocking the retro-beam that we want to measure. There is also a bright rejected beam headed to ZM6 which is only there as the waveplate is changing polarization is making some of the beam rejected by the TFP. They touched the retro mirror to improve it.
They alternated power measurements from position B (the beam that should be isolated by the OFI) and then position A (to measure the power from the laser). Used 10 seconds of statistics mode data for each with the Thorlabs power meter.
Starting measurements at 10:01 PT:
Similar measurements by LLO in 58791 and 2021 from LHO in lab 59410.
AS_C sees this beam, measuring 360uW. It is not centered, -0.4 in Pit and -0.4 Yaw, see attached. When we set up the aux laser it was also off in this direction (-0.6, -0.6) 79300: similar enough.
Betsy and Shieal added a waveplate before the OFI in the AUX path and checked that the forward KTP rejected beam to OFI_B was seen, attached.
In parallel, we turned on the SQZ laser and checked that the SQZ dither lock was stable (0.94mW on OPO_IR_PD) with 75mW of SEED injected. Keita and I opened SQZT7 and adjusted ZM4 and ZM5 to be better centered on the irises. We still didn't have much beam on AS_C but after I further adjusted ZM4 (sdf's not saved), we could see it, see attached.
Betsy is working on replacing the osem magnet I knocked from it's correct position in 79316.
Daniel, Sheila, Camilla. We checked that when we turned the OFI TEC control off (before venting) the "room temp" of the chamber is 21.1 deg. WE might not be able to get this low with the TEC on but will plan to run the OFI TEC closer to 22deg than 25deg once back up.
Retro reflected beam should have been ~80% of the size of the IFO beam in the OFI.
According to Sheila the retro mirror was placed ~35cm downstream of OM1 (between OM1 and OM2). Using this number and the measured beam size of the AUX laser in the lab, the beam width of the AUX beam forward (green) and back (blue) propagating beam are plotted in the attached together with the IFO beam size. In this plot, x axis would be zero at OM1.
As a visual aid, I drew the central 18" part of the OFI cage in the HAM5 drawing. On the plot, again as a visual, aid, this 18" range is drawn as two vertical lines. All optical components of OFI should be in this 18" range, FYI they are all mounted on a single 16"-long metal plate (D2000043) though I don't know the position of that plate relative to the cage.
LVEA LASER Safe transition:
Oli and Ibrihim have transitioned the LVEA to LASER safe.
Work Permit: 12011
Dew point measurement taken this morning read at -43.9 oC. Measurement taken before any activity inside chambers. Soft covers were on HAM5 and HAM6, HAM7 is isolated and a bit pressurized.
End of the day dew point measurement, at -43.0 oC.
Wed Jul 31 08:08:59 2024 INFO: Fill completed in 8min 55secs
Gerardo confirmed a good fill curbside.
TITLE: 07/31 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
SEI_ENV state: MAINTENANCE
Wind: 10mph Gusts, 6mph 5min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.07 μm/s
QUICK SUMMARY:
H1 is still down for maintenance:
Expected LVEA work today as descriped in the LHO HAM5 V1 Document ES400260:
Measure Isolation - new simpler plan suggestion from LLO (cube between SRM and OFI…) Backup - Need Aux laser in HAM6 as LLO#58791, 58848
If out of spec, adjust TGG crystal location (slots in mount)
Inspect/deal with beam dumps if not done already
Before closeout
Robert in-chamber pictures
Finish testing Fast Shutter, trigger HV
See HAM6 closeout checklist
Rebal OFI
Reinstall OFI Glass shroud
Check AS and WFS, Viewport simulator to check beams coming out
Unlock ISI
Unlock retest SUS/SEI
HAM5 closeout FIRST CONTACT ON SRM 1” WITNESS OPTIC, RH READER
Opportunistic Tasks during vent and pump down work (see Betsy for coordination after July 29th:
ZnSe Window install(s) - would need to vent manifold section(s)
HAM8 in-vac cable troubleshooting
HAM2 SEI controls tune-up
Sheila, Keita, Jennie, Camilla
After practicing with the damaged Fused Silica (FS) wedge, Sheila and I installed the new FS wedge. Labeled E1900361 S/N 07 Run# P20-378, 379. We noticed some dust/fiber on the FS after install (didn't inspect before) so Keita wiped with a clean swab. Photo's after cleaning are first and second attachments.
Yesterday 79351 we found indium foil between part (3) and (5) of the FS assembly D2000037 where the (6) screw contacts. Rodica reccommended we add a new piece of indium foil. Third photo attached.
Keita installed the FS holder ot the assembly and we adjusted roll by eye. We installed the assembly onto the OFI. We reinstalled the beamdump bar (never moved dumps on it but wiped them yesterday) and the baffle bar and baffle. Baffle was installed in the same location, touching the double thick beamdump. We then unlocked the OFI and reinstalled the nominal motion limiter screws.
We then transitioned to laser hazard, the retroflection of the aux beam looked good and we checked that SRM was in it's nominal position. No reason to go to SR2.
The beam through the OFI started very (50mm?) low and was hitting the fast shutter. We then adjusted the roll of the FS wedge assembly to correct for any pitch, it was hard to make fine adjustments and tightening the screw moved the beam. It was a little off in yaw. Keita has photos of the beam position.
We repeated yesterday's 79344 throughput power measurements with more laser power:
The rejected beam to SQZ goes through ZM6 baffles, and around the middle of the HAM7 GV.
Sheila then headed to SR2 and checked that the beam was centered in pitch and yaw.
After taking IR photo, the beam position on the iris close to OM1 seems to be off by about ~2.75mm/2 radius from the center of the iris at 45 degrees angle, i.e. it's too low by ~1mm and to the +X direction in YAW by ~1mm. Look at the 1st picture looking at the iris from the direction of HAM5. There's no parralax though its more focused on visible light than IR.
1mm too low and 1mm to +X don't sound like a big deal, once we have the IFO we should be able to change the beam positions on SRM/OFI and SR2 to get back higher and to the -X if necessary. Remember that the iris was set using the beam we believe to reproduce the alignment before the second crator incident, and we have found that the beam was too high on OM1 using that beam. So the beam being too low on the iris could be a good thing. But we'll make sure that we can see the beam on ASC-AS_C.
The 2nd picture shows that the diameter of the iris hole is a tiny bit larger than 2.5mm but smaller than 3mm.
Roll adjustment of the fused silica wedge is not that easy at this level (1mm over maybe 2.5m? distance), a tiny rotation results in big change and loosening/tightening the set screw for the rotation seems to change the deflection. As far as we see the beam on ASC-AS_C we won't adjust the FS wedge further as this won't change the isolation/throughput etc. of the OFI.
Serial number of the original FS wedge is 001 according to Rodica.
From what Camilla wrote above, the new one we've just installed is S/N 007.
Not including the first measurement where the laser power was clearly lower, we calculated with attached:
Transmission: 99.82% with stdev 0.72%
Ratio rejected by TFP: 0.188% with stdev 0.004%
The sum of these is 100.01%, which is within the margin of error.
Tagging for EPO.
Sheila, Keita, Betsy, Camilla
In the last power measurements in 79313 we were loosing 25% through OFI and another 15% from lost through incorrect polarization through the TFP.
Today's measurements:
From the mean of these measurements Sheila and Louis calculated the rejected ratio (power sent to ZM6) is 0.17 ± 0.002%. The transmission through to HAM6 is 99.96 ± 1.45%. The sum of these is 100.13%, which is within the margin off error.
Attached is a .txt version of the .py file Sheila did this calculation in.
We realized that we overestimated the errors here so the transmission through to HAM6 is 99.96 ± 0.84%. Rejected ratio (power sent to ZM6) is 0.17 ± 0.001%. Updated code attached and more recent measurements (with swapped FS) in 79383
Keita, Sheila
Summary: We chipped the spare KTP crystal this morning, and this afternoon installed the back up spare that Rodica had shipped. We've adjusted the roll, and the pitch angle seems better than the crystal that we removed. So this should be ready to go into the chamber first thing Monday morning. We have many photos from today, which will be attached and annotated to this alog later.
Following on From Jason's alog 79319
With this placement of the damaged KTP in it's assembly, where the assembly is bolted perpendictular to the beam path, and a wave plate to mix the polarizatoins upstream of the KTP, we have 13.5mW in the p polarized beam (see first attachment which is a diagram Paul sent us this morning), 16.3mW in the s polarized beam, and 2.3 mW in the AR surface. This is not set up with the AOI that the AR coating is designed for, which is why the AR beam is large, we can take advantage of this to set the pitch by setting the AR reflection parallel to the table..
With the original KTP in place, the AR reflection isn't parallel to the table it is pitched up by 10/(530 +405 mm) about 11 mrad. The optic lab beam is hitting the KTP a little below the burned spot, which would have been on the +X side in chamber. The burned spots are on the side closer to our alignment laser.
Before taking it out of the mount we took a variety of photos showing the damage spots position. We did not find any indium foil in the mount, Paul had warned us that there might be indium between part 5 and part 9 of D2000038.
As we were placing the new crystal in the mount, we left the set screws (11) that hold the peek loose, and held the piece upsidedown while we screwed in the bolts labeled #10 to hold on the aliuminum plate. It chipped as we were tightening the bolts labeled 10 in D2000038. After some discussion with Rodica, Paul, Gabriele, we went back to the lab to take photos of the chip and try to understand how the chip happened. We have photos showing that the crystal was proud of the top of part 5, the orientation of the black metal piece. After we removed the black front plate, we could see that the KTP was firmly stuck in part #5, with the wedge stuck. Keita had to push on the back of the crystal to get it loose.
Keita made a series of measurements using calibers:
Chipped KTP: (agrees well with the drawing: E1900284)
part 5: https://dcc.ligo.org/DocDB/0171/D2000567/001/D2000567_A%2B_OFI_KTP_Wedge_Holder.pdf
peek:
total height (max): crystal + peek = 0.885+0.1105 = 0.9955 inches, smaller than 0.2mm than the height of the slot.
cratered KTP:
We then did a trial run (using the chipped KTP) of an approach that we think avoids the problem of letting the KTP get wedged in the holder. We set the KTP on several wipes on the bench, and set the peek underneath it. We then slid the holder (part #5) over this whole thing, which went smoothly, and tightened the set screws. After flipping it over, we can see that the KTP is not proud of part #5, and it sits nearly flush to the front of the holder. We could then easily attach the black front plate. We decided to do this with the final spare, which had 2 small chips on the edge.
With that spare installed in the assembly, we adjusted roll using the alignment laser that Camilla and Jason set up. We wanted to adjust roll so that the transmitted beams were level to the table, since we know that the laser bea we started with were parallel to the table. The roll adjustment was sticky, and tightneing the set screw tended to lower the transmitted beams. The beams transmitted are off in yaw compared to the ones from the cratered KTP, by about 7mm/870mm + about 8 mrad. We had difficulty seeing the AR reflected beam, but we can see a tiny beam with all the lights off (this suggest that the reason the beam was so bright before was the coating damage, not the AOI of the crystal in our set up.). At 820 mm from the KTP, the AR beam was about 1 mm too low, so it's pitched down by 1mrad.
We think this is about as good as we can do by adjusting with this mount, so we are satisfied and will leave the KTP assembly under wipes and foil to be reinstalled on Monday.
Photos showing the location of the crater damage spots, and how the crystal was mounted in the holder as found.
Photos showing the chipped crystal. The second photo shows some small chips on the back edge, we noticed these just before the crystal chipped. Rodica says those look similar to things she has seen in these crystals, so this might be something that was present before today. The front of the crystal has a large chip and damage along the bottom, those both happened while tightening the bolt on the front plate.
Photos of how the damage probably happened. The crystal was proud of the aluminum holder, visible between the aluminum and the black piece in the first photo. The next two photos show that there was space between the back of the holder and the thick part of the wedge on both the top and the bottom.
The last 4 photos are side on views from 4 sides showing how crystal was sticking out in front of aluminum holder.
The MTP was lodged tightly in the aluminum holder and wasn't easily dislodged, the last photo shows how Keita slid the peek out from under it and the crystal was still stuck tight.
When we took the cratered KTP out to measure it, a speck of black seems to have fallen out of one of the craters.
final photos for today show how the beam out of the new crystal was off in yaw compared the the crater damaged crystal. The irises were placed on the transmitted beams through the crater damaged crystal by Jason before we swapped.
Video of the installation of new KTP in the KTP holder (without breaking it) was uploaded to https://dcc.ligo.org/G2401494 as it is too big to attach to alog.
Note that the table surface (and therefore the face of the holder facing the table in the video) is NOT perpendicular to the cylindrical surface of the holder. Attached is a cartoon of the side view of the installation shown in the video. (86 deg in the cartoon is just an eyeballing, but it should be larger than 80 deg, smaller than 90).
The problem seems to be that the height (which you cannot see in the cartoon) of the KTP as well as PEEK cushon (which you cannot see in the cartoon either) combined is so close to the height of the slot in the holder that a slight rotation of KTP relative to the holder around x axis will easily wedge the KTP in place.
For posterity, below is a table of KTP wedge serial number.
| S/N | Description | ICS |
| 3005 | The original wedge with laser damages (aka cratored one). | TBD |
| 3004 | The first replacement that we chipped. | https://ics.ligo-la.caltech.edu/JIRA/browse/E1900284-2-Aplus-3004 |
| 3001 | Pristine one that we installed in HAM6. | TBD |
S/N 3004 and 3005 will be sent to GariLynn.
Another great pic of the laser damaged KTP.
Table of KTP wedge serial number with newly made ISC links for SN3005 and 3001. Thanks Mitch for making these records!
| S/N | Description | ICS |
| 3005 | The original wedge with laser damages (aka cratored one). | https://ics.ligo-la.caltech.edu/JIRA/browse/E1900284-2-Aplus-3005 |
| 3004 | The first replacement that we chipped. | https://ics.ligo-la.caltech.edu/JIRA/browse/E1900284-2-Aplus-3004 |
| 3001 | Pristine one that we installed in HAM6. | https://ics.ligo-la.caltech.edu/JIRA/browse/E1900284-2-Aplus-3001 |
Tagging for EPO.
Sheila's original video is ~2sec footage of fast shutter, supposedly at 150 fps according to the file metadata.
Attached is an edited video that shows the 50ms of FS action slowed down by a factor of 10. "SRC TC" is the time elapsed since the start of (Sheila's original) video multiplied by a factor of 10, i.e. 1 sec in SRC TC is actually 100ms. This timestamp is not to be trusted at the lowest digit of sub-second (ms level in reality) because there's some frame interpolation going on due to mismatch between the standard output frame rate of 24FPS VS the source frame rate (150 slowed down to 15 FPS). Anyway, the mirror goes down lower than the closed position right after the initial thrust of the HV fast shutter motion, and even a few bounces after that, before the shutter eventually settles to the permanently closed position.
Also attached is an annotated png file of four frames ("Open", "HV thrust", "Bounce to the bottom" and "Close").
In light of recent failure of the replacement FS at LLO where the mirror broke off due to the hard stops that were set too low, and a comment by Rich (LLO alog 73584) I watched the video of the LHO unit again (see my entry above).
Though LHO video was shot from the side where we cannot see the position of the hard stop, the bobbin might be hitting the stops right after the launch even though the height of the stops looks good to my eyes. See TC~00:00:05:06. And the bobbing oscillates several times though it never hits the stops again.
Does this mean that the magnetic braking is too weak?