Modal model for the new SRC

Starting from the input beam model described in alog 30126, I expanded the modal model to include the new arm cavities and new SRC.

The optics location data is based on:
- https://galaxy.ligo.caltech.edu/optics/ for optics ROC and glass thicknesses
- E1400205 for BS, ITMX, ITMY, SR3, SR2 and SRM locations (SR2 location moved by 5cm towards the BS compared to E1400205)

While the code is a bit lengthy, it only builds simple structures describing sections of the interferometer:

SRCrt = 

    lambda: 1.0640e-06
         q: -1.8528e+03 + 4.0141e+02i
         N: 8
      dist: [0 0 24.4907 15.4657 15.7441 15.7441 15.4657 24.4907 0]
      ifoc: [-0.0010 -2.3180e-04 0.0555 -0.3113 -0.3522 -0.3113 0.0555 -2.3180e-04]
     label: {'ITMback'  'ITMlensr'  'SR3'  'SR2'  'SRM'  'SR2r'  'SR3r'  'ITMlens'}

XARM = 

    lambda: 1.0640e-06
         q: -1.8377e+03 + 4.3420e+02i
         N: 2
      dist: [3.9945e+03 3.9945e+03 0]
      ifoc: [8.9119e-04 0.0010]
     label: {'ETMX'  'ITMX'}

YARM = 

    lambda: 1.0640e-06
         q: -1.8356e+03 + 4.3599e+02i
         N: 2
      dist: [3.9945e+03 3.9945e+03 0]
      ifoc: [8.9012e-04 0.0010]
     label: {'ETMY'  'ITMY'}

Here the relevant fields are:
q: input beam parameter
N : number of optics
dist : distance between the optics (d/n if in glass, i.e. NOT optical thickness d*n, since this is only for the modal calculation); one more than optics
ifoc : inverse focal length (either 1/f for lenses or 2/R for reflective optics)1 label: label of optics
 

The cavity overlap in the model is quite good:
Mode-matching of PRC to average arm: 99.9976 %
Mode-matching of PRC to X arm: 99.9988 %
Mode-matching of PRC to Y arm: 99.9959 %
Mode-matching of SRC to PRC: 99.8424 %
Mode-matching of SRC to X arm: 99.8136 %
Mode-matching of SRC to Y arm: 99.7878 %
Contrast defect between x and y arm, incl Schnupp asymmetry, but without reflectivity imbalance: 5.0033e-06
 

Note that without the 5cm SR2 move that was just completed the SRC looks significantly worse:
Mode-matching of SRC to PRC: 96.8874 %
Mode-matching of SRC to X arm: 96.7677 %
Mode-matching of SRC to Y arm: 96.666 %

 

The code is located at /ligo/home/controls/sballmer/20171207/beamCalc.m. It uses custom MATLAB libraries in /ligo/home/controls/sballmer/lib. The library includes a number of mode propagation plotting and overlapping tools.

Estimating the new contrast defect

Stefan, Thomas

In light of the new ITMX and ETMs being installed before O3, Stefan thought it would be a good idea to try to estimate the new contrast defect by calculating the fundamental mode of  each arm cavity before and after the swap using data from the core optics galaxy page and propagating the beams to a common point and calculating the contrast defect via this equation:

Two methods:

- Stefan used handwritten MATLAB code,which is located in ligo/home/controls/sballmer/20171207,  takes into account the arm cavity modes and the Schnupp asymmetry.

- I used Finesse with the aLIGO design and modifying the optics to the most in-situ numbers for ROCs (attached .kat parameter file and custom function to find eigenmodes).  This model includes the arm cavities and the Schnupp asymmetry, as well as the thermal lens which is approximated at f=34.5km and the michelson length.

When looking at the contrast defect on the HR surface of the arm cavities, both models are consistent, which makes sense because its the simplest calculation.  However, when propagating the beam to a different point such as the beamsplitter, things get more complicated because of the lenses caused by the AR surface of the ITMs and beamsplitter are estimates at best.  Although there is a slight difference in the q-parameters between the two models because of these effects, the way we calculated the contrast defect is the same.

The parameters we used were as follows:

Both simulations used the same ROC numbers, arm cavity length of 3994.5 meters and Schnupp asymmetry = 0.08m

Before Swap

	S/N	RoC
ITMX	03	-1939.90
ITMY	11	-1939.20
ETMX	08	2241.54
ETMY	12	2238.90

 

After Swap

	S/N	RoC
ITMX	07	-1940.30
ITMY	11	-1939.20
ETMX	13	2242.20
ETMY	16	2246.90

 

Results

Finesse

Location	Old Contrast Defect	New Contrast Defect
ITM HR Surface	5.93e-6	3.87e-6
BS HR Surface	5.68e-6	4.59e-6

Stefan's Code

Location	Old Contrast Defect	New Contrast Defect
ITM HR Surface	5.93e-6	3.87e-6
ITM + Schnupp	5.63e-6	5.00e-6

In the end, the interesting part which both models  agree on is that the contrast defect should be better with the new test masses.

It is important to note that we've only really considered the modal overlap, this has not incorporated the reflectivities of the ITMs which could make a difference in the end results if they are substantially imbalanced.  

HAM2 vacuumed and wiped - IMs are still moving around, 4 more bolts to tighten

Vacuumed in HAM2, using this combination of vaccum hoses:

• tiger vac
• vacuum hose covered in a new clean C3 cover
• adaptor that attaches to about 30 inches of plastic hose (~1.2inch, wiped outside and IPA run through the inside)
• Kapton tub

The Kapton tube was class-A, so I used it to vacuum horizontal surfaces in MC3, MC1, PR3, IM1, and IM3 cages, and I did use it in contact with the metal.

I kept close track of the space under the +Y MC3 blade spring, and from this test area I can see that larger particulate are picked up by the vacuum, but smaller particulate are not, and when I wipe with a IPA wipe, the small particulate are removed.  Picture attached.

I put IM1 on EQ stops and used the vacuum to remove a large particle on the upper portion of the face of IM1, and this was successful without any contact between the optic and the Kapton tube.

I used the same technique to remove large particulate from the MC REFL periscope 2 lower mirror, which was very contaminated.  Not all of the particulate that I could see would come off of the optic, so some may be scratches that have been present since install.

Given my conclusion that vacuuming leaves small particulate, I wiped over all of the surfaces that I could reach in HAM2 from both the West and East doors.

PRM stage M2 has OSEM flags on the HR side of the tower that do not go into OSEMS, and the -Y flag has shifted out of place, and will need to be restored.

The really big story is that IM1, IM2, and IM3 shifted in alignment between 50 and 1500urad, and I have only one explanation for this, which is that the 4 8/32 bolts that hold the top plate to the side plates are loose, and will need to be tightened.

These bolts are covered by the brackets that hold the blade spring EQ stops at the top of the tower, so the brackets will need to come off to give access to the remaining 4 loose bolts.

This also reveals that the root cause of the shift I saw in IM3 after the B&K, a shift  I recreated myself by tapping with a dog clamp on the top plate, are these 4 hidden loose bolts.

Opened FRS Ticket 9573.

Note, however -- while we agree that alignment pins in the cage (as suggested in the FRS) would do well to remove the slop described -- after further investigation Cheryl found much more success in relieving the pitch adjustment screws and re-engaging them on IM3. The guess is that they had been over stressed, warping both the top plate under discussion among other things. Not a solid case, but IM3 cage / OSEMs no longer moves / move when you look at it wrong.

Cheryl Still in the LVEA

   00-:25 (16:25) Cheryl is still in the LVEA working on the closeout of HAM2. She will post her LVEA exit in the aLOG when she is finished.

Install ITM-Y Camera

   Kentaro, Jeff B. 

   We installed the ITRM-Y camera in its housing; and took a couple of test shots just to verify things were working. Monday we will start dialing in the camera and finalize the the camera mounting and alignment.   

WHAM5 ISI Final scan and Unlocked

Looks clean.  Unlocked ISI and left with covers pulled out so TFs can be run.  Have updated the positions for isolation and committed (HAMs 3 & 4 as well to svn:

hugh.radkins@zotws9:burtfiles 0$ svn st -u
        *    10241   ISI_ETMY.hughdonotmonitor~
        *    10241   ISI_ITMX.hughdonotmonitor~
        *    10241   ISI_ITMY.hughdonotmonitor~
M            15862   h1isiham4_OBSERVE.snap
M            16444   h1isiham3_safe.snap
M            16444   h1isiham4_safe.snap
M            16444   h1isiham5_safe.snap
M            15862   h1isiham3_OBSERVE.snap
M            15862   h1isiham5_OBSERVE.snap
Status against revision:  16483
hugh.radkins@zotws9:burtfiles 0$ svn commit -m "Update snaps for CPS control DC Position" *.snap
Sending        h1isiham3_OBSERVE.snap
Sending        h1isiham3_safe.snap
Sending        h1isiham4_OBSERVE.snap
Sending        h1isiham4_safe.snap
Sending        h1isiham5_OBSERVE.snap
Sending        h1isiham5_safe.snap
Transmitting file data ......
Committed revision 16484.
hugh.radkins@zotws9:burtfiles 0$ pwd
/opt/rtcds/userapps/release/isi/h1/burtfiles
hugh.radkins@zotws9:burtfiles 0$

Shift Summary - Day

TITLE: 12/09 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
LOG:

16:00 LVEA is LASER SAFE

16:12 Vanessa and Karen out

16:28 Kantoro and Umakant to visit the roof for the view.

16:40 Kantoro and Umakant back inside and going for a drive to EX to have a look around outside.

16:43 Mark and Tyler out

17:00 Kantoro and Umakant back

17:05 Hugh in to LVEA/ HAM5 for ISI locking/payload documenting

17:12 Fil into LVEA/HAM5 for ground loop checks

H1:IMC-PWR_IN_OUT1617:22 Travis in to biergarten and HAM5

17:26 Betsy into LVEA/HAM5

17:33 Mark and Tyler into LVEA (TMDS)

17:30 Jeff B and Rakesh into LVEA to inspect cleanrooms

18:00 LVEA is LASER SAFE

18:02 Richard into LVEA/HAM5

18:05 Rakesh out

18:15 Jeff B out

18:20 Sheila going into the opticslab/squeezer bay

18:23  Chandra in to LVEA/GV4

18:36 Stefan in to LVEA/HAM5

18:37 Bubba in to LVEA

18:47 Stefan out

18:55 Cheryl in to LVEA/HAM2 for vacuuming

19:30 Sheila into LVEA w/Umakant

19:35 N out of optics lab

19:54 N back to optics lab

19:55 Bijesh into LVEA/HAM5

20:02 TJ into LVEA/HAM5

20:05 Karen and Vanessa leaving EX for Corner

20:09 Richard out

20:12 TJ out

20:18 Richard out

20:20 Bubba, Mark, Tyler, Travis, Betsy and Terry out

20:40 N out

20:52 Cheryl out

20:56 Betsy in to LVEA/HAM5

20:57 Travis into LVEA

21:03 Hugh out

21:06 Betsy into LVEA

21:09 Richard into LVEA

21:23 Jeff B and Kantoro in to LVEA

21:28 Chandra in to LVEA

21:30 Mark and Tyler in to LVEA

21:31 Richard out

21:41 Chandra out

21:52 Cheryl in to LVEA/HAM2

21:51 Fil in to LVEA/TCS tables (testing access system)

22:03 Bubba to the LVEA

22:04 Kyle in to LVEA/HAM4-5 (top of tube)

22:13 Bubba out

22:19 N in to LVEA/Squeezer

22:20 EX HEPI Pump Controller restarted

22:43 Terry in to LVEA squeezer bay

22:45 N out

23:00 TJ and Sheila in to LVEA

23:02 Fil in to EY

23:20 Hugh into LVEA/HAM5

23:25 Travis out

23:26 Chandra in to LVEA

23:27 Betsy out

23:38 Chandra out

32:41 N into LVEA

23:43 Hugh out

HAM5 Closeout Status COB

Betsy, Travis, Hugh

So, turns out we couldn't get the doors on HAM5 by COB because everything took longer than expected today (cable entry below) and everyone has already put in ~6 days of work this week.  However, we completed the entire list up to actualy putting the doors back on.

 

Things we did to enable doors going on first thing Monday morning were:

SR3

Pulled F.C. from HR surface, blew N2 for ~ a full min.

Unlocked optic.

Recenter some M1 flags - after 20 mins of knocking the optic around we decided they were good enough because we didn't want to risk breaking a magnet off or compromising cables again this late in the game.

Recentered M3 stage AOSEMs.

Fought with DTT and the suspension to eventually get quick TFs in all 6 DOFs at top stage - L has low coherence after 0.7 which doesn't look great, but below that where all of the peaks are, things line up nicely - PASS

SRM

Pulled F.C. from HR and AR surface, blew for ~30 sec on each.

Unlocked optic.

Took quick TFs of 6 DOFs - all look good - PASS

OSEM centerings are good.

 

Executed Exit Chamber procedure for tool sweeps, cleaning, 3" horizontal wafer placement, 1" witness optic FC removal, subsystem signoffs, etc.

Hugh unlocked ISI.

Jim will take the opportunity to run measurements on HAM5 ISI tonight.

BUBBA - YOU ARE A GO FOR DOOR INSTALL ASAP MONDAY MORNING.  I will follow up on text, and let you know if any status changes.

 

shroud fit on GV4

[Bubba, Chandra, Mark, Tyler]

11am-12:15pm local

Test fit first article shroud on GV4 today and used west crane.

Particle count in biergarten looked ok.

Ken can reconnect power cables at his convenience.

 

WHAM5 ISI Table Balance

After the cable replacement on HAM5 as BWeaver noted, I consolidated weights on a few corners where needed.  This and the re-cabling with a few more clamps added resulted in some changes to the counter weights.  But it all balances nicely now and I'll update the weight plan shortly.  I left it locked for SUS to continue and will unlock when needed.

HAM5 Closeout activities - this morning

Since Hugh had done some cable lacing on the ISI during yesterday's payloading exercise, Fil wanted to check the grounding on HAM5 again.  Of course, he found issues with ZM2.  Hugh, Richard, Fil, and I embarked on quite a bit of troubleshooting whereby we ended up replacing the entire D1000225 (SRS) and D1000234 (quadrapus) cables from ZM2 to the feedthru.  It turned out that the SRS cable had a bad end at the feedthru, and the quadrapus was fussy at one or more BOSEM connections.  We think that the grounding checks yesterday were actually null because during the troubleshooting, we discovered a few connections that hadn't had their fasteners secured in this chain yet.  It seems the ZM2 is everyone's problem, therefore it is no one's problem.

Meanwhile, Travis climbed into the HAM5 Table West tube section, removed baffles (again), locked the SR3 and SRM and painted FC on their HR surfaces.  We replaced the baffles (which have to come off again in order to pull the FC) so that Hugh could recheck the ISI balance, which he is doing now.

Travis and I will head back in shortly to finish the FC and cleanup work - hopefully doors will go on this aft.

SR2 cage B&K measurements look different

I took JeffK's recent B&K data for SR2 and plotted it against Arnaud's data from 2014 (alog 12089). Jeff's measurement is very different from what Arnaud found. There is a new resonance at 50 hz in both degrees of freedom that is sharper than any of the resonances from the 2014 measurement. Talking to Jeff and looking at Arnaud's setup, it looks like the sensors were in different spots, but the strike locations were the same.  It also seems that my tfs on HAM4 on Nov 8th show this some, second attached image is the gs13 cartesian tfs from that measurement. The 50hz feature shows up most in the rotational dofs, but is pretty small. I don't think it's hepi, because the other chambers don't see a similar feature.  Not sure if this will be an issue for the ISI controls yet, but probably not. Jeff also suggested SR2 was locked for this measurement, so I'll try a shorter set of tfs tonight before I leave, if the LVEA gets quiet.

Shift Transition - Day

TITLE: 12/08 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 2mph Gusts, 1mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.40 μm/s
QUICK SUMMARY:

15:07 Vanessa and Karen into LVEA

15:29 Mark and Tyler into LVEA HAM5 (doors)

15:30 lost comms w/EX HEPI pump controller

 

Hugh walked me through the instructions in the wiki for restarting the end X HEPI EPICS IOC and recovering the PID.

TCSx and TCSy Realigned

J. Oberling, T. Shaffer, T. Sadecki, B. Weaver, A. Brooks (remote support)

Today we completed the initial alignment of the TCS tables (after Greg placed them in their new positions last week) to their respective in-vacuum mirrors.  Both tables were aligned via the following steps:

• Align the red alignment laser to the on-table irises that mark the path of the CO2 beam.
  • The alignment of these irises was checked when Alastair was up for the final time in September.
• Adjust the bottom periscope mirror to center the beam on the ZnSe viewport.
• Adjust the top periscope mirror to center the beam on the 1st in-vacuum gold mirror.
• Adjust the 1st in-vacuum mirror to center the beam on the 2nd in-vacuum mirror.
• Adjust the 2nd in-vacuum mirror to center the beam on the CP.

That being said, it wasn't that easy.  Both alignment lasers needed to be realigned to the irises.  In fact, the alignment laser for the TCSy table needed to be installed before it was aligned.  The real problems, however, came when attempting to align the beam through the ZnSe viewport and onto the 1st in-vacuum mirror.  Regardless of how we adjusted the periscope mirrors, we always ran out of range before we could center the beam on the viewport and the 1st in-vacuum mirror.  The top periscope mirror (TPM) is bolted to a plate, that then bolts to the periscope structure itself via slots in the plate; this plate can therefore be moved up and down on the periscope structure (the drawing for the periscope assemble lives at D1200953).  We tried moving the TPM up and down, but regardless of its position on the periscope structure, we always ran out of adjustment range before the beam was aligned.  The problem is due to an apparent design flaw in the plate.  The plate holds the TPM at a fixed angle, and this angle is apparently not the correct angle for properly aligning the beam.  In order to center the beam on the ZnSe viewport and the 1st in-vacuum mirror, we had to remove all the screws from the TPM plate except for one, rotate the plate on the periscope structure, and secure it with whatever screws lined up.  This was necessary for both TCSx and TCSy.  TJ has pictures of the results that he will post as a comment to this alog.  Long story short, the TCSx TPM is now held on by 2 screws and 1 dog clamp, while the TCSy TPM is held on by 1 screw and 1 dog clamp.  We are not in love with this solution, but it was the only way we could align the beam to both the ZnSe viewport and the 1st in-vacuum mirror.  We emailed Aidan about this and he informed us this was not too surprising due to the table being further away from the chamber.

Once we had the beam in-vacuum, Travis and I entered the chamber and, with TJ assisting from the outside, we aligned each beam to its respective CP.  The alignment from the 1st to the 2nd in-vacuum mirror was trivial, but adjusting the 2nd in-vacuum mirror to align the beam onto the CP was very difficult.  The mirror has 8 screws that are arranged in what appears to be a pattern that allows for push-pull adjustment of the mirror alignment, but in reality that doesn't work at all.  All the screws screw directly into the mirror, so there is no push-pull.  The only way we could reliably align this mirror was to loosen all the screws, and then slowly re-tighten them one at a time in such a way that the beam remained centered on the CP.  This was made difficult by the fact that tightening/loosening each screw had a counter-intuitive effect on the beam alignment; i.e. we would tighten a screw on the right side of the optic expecting the beam to move right (since we're pulling the mirror in that direction) but it was a toss-up as to whether the beam would go right, left, or just not move at all.  After several iterations of tightening and loosening screws we finally got the beams aligned to the center of their respective CPs.  This completes the initial alignment of the TCS tables to their in-vacuum mirrors; a fine alignment will be done once the HWS table is re-installed and aligned and the CO2 lasers are hooked up and running again (the HWS is used to image the heating provided by the CO2 lasers, and the TCS TPMs are then adjusted to center the CO2 beam on the CP).

HAM 4 annulus pump down

Pumping HAM 4 annuli with aux cart #5 and hung turbo. Started at 3:39pm local. After 10 minutes of pumping, CC gauge reads 4.3e-4 Torr.

unexplained alignment change in IM3

I checked the alignments of the IMs since I finished working yesterday, and found that IM1, IM2, and IM4 recoverd their alignments when restored this morning, but IM3 did not, it has a significant change in alignment in pitch and yaw.

IM3 change in pitch is ~-1000urad, and change in yaw is ~-1500urad, however the alignment sliders are at (0,0), and have been since yesterday, so there's no apparent reason for the change.