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New entries since:Wed Dec 31 16:00:00 1969
IDup Date Author Type Category Subject
  16849   Thu May 12 20:11:18 2022 AnchalUpdateBHDBHDBS Output beams steered out to ITMY table

I successfully steered out the two output beams from BHD BS to ITMY table today. This required significant changes on the table, but I was able to bring back the table to balance coarsely and then recover YARM flashing with fine tuning of ITMY.

  • The counterweights were kept at the North end of the table which was in way of one of the output beams of BHD.
  • So I saved the level meter positions in my head and removed those counterweights.
  • I also needed to remove the cable post for ITMY and SRM that was in the center of the table.
  • I installed a new cable post which is just for SRM and is behind AS2. ITMY's cable post is next to it on the other edge of the table. This is to ensure that BHD board can come in later without disturbing existing layout.
  • I got 3 Y1-45P and 1 Y1-0 mirror. The Y1-0 mirror was not installed on a mount, so I removed an older optic which was unlabeled and put this on it's mount.
  • Note that I noticed that some light (significant enough to be visible on my card) is leaking out of the 45P mirrors. We need to make sure we aren't loosing too much power due to this.
  • Both beams are steered through the center of the window, they are separating outside and not clipping on any of the existing optics outside. (See attachment 1, the red beam in the center is the ITMY oplev input beam and the two IR beams are the outputs from BHD BS).
  • Also note that I didn't find any LO beam while doing this work. I only used AS beam to align the path.
  • I centered the ITMY oplev at the end.

Next steps:

  • LO path needs to be tuned up and cleared off again. We need to match the beams on BHD BS as well.
  • Setup steering mirrors and photodiodes on the outside table on ITMY.
  16850   Thu May 12 20:24:29 2022 yutaUpdateBHDPOX and POY investigation

[Anchal, Yuta]

We checked POX and POY RF signal chains for sanity check since Xarm cannot be locked in IR stably as opposed to Yarm.
POX beam seems to be healthy. This issue doesn't prevent us from closing the vacuum tank.

POY
 - RF PD has SPB-10.7+ and ZFL-500NL+ attached to the RF output.
 - At the demodulation electronics rack, SMA connectors are used everywhere.
 - With Yarm flashing at ~1, RF output has ~24 mVpp right after RF PD, ~580mVpp after SPB-10.7+ and ZFL-500NL+, and ~150mVpp at right before the demodulation box.
 - There is roughly a factor of 3 loss in the cabling from POY RF PD to the demodulation rack.
 - Laser power at POY RF PD was measured to be 16 uW

POX
 - RF PD doesn't have amplifiers attached.
 - At the demodulation electronics rack, N connector is used.
 - With Xarm flashing at ~1, RF output has ~30 mVpp right after RF PD, and ~20mVpp at right before the demodulation box.
 - Losses in the cabling from POX RF PD to the demodulation rack is small compared with that for POY.
 - Laser power at POX RF PD was measured to be 16 uW

Summary
 - POX and POY RF PDs are receiving almost the same mount of power
 - POY has larger error signal than POX because of RF amplifier, but the cable loss is high

Conclusion
 - There might be something in the electronics, but we can close the vacuum tanks

  16851   Fri May 13 14:26:00 2022 JCUpdateAlignmentLO2 Beam

[Yehonathan, JC]

Yehonathan and I attempted to align the LO2 beam today through the BS chamber and ITMX Chamber. We found the LO2 beam was blocked by the POKM1 Mirror. During this attempt, I tapped TT2 with the Laser Card. This caused the mirror to shake and dampen into a new postion. Afterwards, when putting the door back on ITMX, one of the older cables were pulled and the insulation was torn. This caused some major issues and we have been able to regain either of the arms to their original standings.

  16852   Fri May 13 18:42:13 2022 PacoUpdateAlignmentITMX and ITMY sat amp failures

[Yuta, Anchal, Paco]

As described briefly by JC, there were multiple failure modes going during this work segment. blush


ITMX SatAmp SAGA

Indeed, the 64 pin crimp cable from the gold sat amp box broke when work around ITMX chamber was ongoing. We found the right 64 pin head replacement around and moved on to fix the connector in-situ. After a first attempt, we suddenly lost all damping on vertex SUS (driven by these old sat amp electronics) because our c1susaux acromag chassis stopped working. After looking around the 1x5 rack electronics we noted that one of the +- 20 VDC Sorensens were at 11.6 VDC, drawing 6.7 A of current (nominally this supply draws over 5 Amps!) so we realized we had not connected the ITMX sat amp correctly, and the DC rail voltage drop busted the acromag power as well, tripping all the other watchdogs devil ...

We fixed this by first, unplugging the shorted cable from the rack (at which point the supply went back to 20 VDC, 4.7 A) and then carefully redoing the crimp connector. The second attempt was successful and we restored the c1susaux modbusIOC service (i.e. slow controls).


ITMY SatAmp SAGA

As we restored the slow controls, and damped most vertex suspensions, we noticed ITMY UL and SD osems were reading 0 counts both on the slow and fast ADCs. crying We suspected we had pulled some wires around when busy with the ITMX sat amp saga. We found that Side OSEM cLEMO cable was very loose on the whitening board. In fact, we have had no side osem signal on ITMY for some time. We fixed this. Nevertheless the UL channel remained silent... We then did the following tests:

  • Test PD mon outputs on the whitening card. We realized the whitening cards were mislabeled, with ITMX and ITMY flipped angry. We have labeled them appropriately.
  • Tested input DB15 cable with breakout board.
  • Went to the ITMY sat amp box and used the satellite box TESTER 2 on J1. It seemed correct.
  • We opened the chamber, tested the in-vacuum segments, they all were ok.
  • We flipped UR-UL OSEMs and found that the UL OSEM is healthy and works fine on UR channel.
  • We tested the in-air cable between satellite box and vacuum flange and it was ok too.
  • We suspected that the satellite box tester  is lying, so we replaced the satellite box with the spare old MC1 satellite box, and indeed that solved the issue.

DO NOT TRUST THE SATELLITE BOX TESTER 2.


Current state:

  • IMC locking normally.
  • All suspensions are damping properly.
  • Oplevs are not centered.
  • No flashing on either of the arms. We had no luck in ~20 min of attempt with just input injection changed.
  • On kicking PR3, we do see some flashing on XARM, which means XARM cavity atleast is somewhat aligned.
  • All remaining tasks before pumpdown are still remaining. We just lost the whole day.
  16853   Sat May 14 08:36:03 2022 ChrisUpdateDAQDAQ troubleshooting

I heard a rumor about a DAQ problem at the 40m.

To investigate, I tried retrieving data from some channels under C1:SUS-AS1 on the c1sus2 front end. DQ channels worked fine, testpoint channels did not. This pointed to an issue involving the communication with awgtpman. However, AWG excitations did work. So the issue seemed to be specific to the communication between daqd and awgtpman.

daqd logs were complaining of an error in the tpRequest function: error code -3/couldn't create test point handle. (Confusingly, part of the error message was buffered somewhere, and would only print after a subsequent connection to daqd was made.) This message signifies some kind of failure in setting up the RPC connection to awgtpman. A further error string is available from the system to explain the cause of the failure, but daqd does not provide it. So we have to guess...

One of the reasons an RPC connection can fail is if the server name cannot be resolved. Indeed, address lookup for c1sus2 from fb1 was broken:

$ host c1sus2
Host c1sus2 not found: 3(NXDOMAIN)

In /etc/resolv.conf on fb1 there was the following line:

search martian.113.168.192.in-addr.arpa

Changing this to search martian got address lookup on fb1 working:

$ host c1sus2
c1sus2.martian has address 192.168.113.87

But testpoints still could not be retrieved from c1sus2, even after a daqd restart.

In /etc/hosts on fb1 I found the following:

192.168.113.92  c1sus2

Changing the hardcoded address to the value returned by the nameserver (192.168.113.87) fixed the problem.

It might be even better to remove the hardcoded addresses of front ends from the hosts file, letting DNS function as the sole source of truth. But a full system restart should be performed after such a change, to ensure nothing else is broken by it. I leave that for another time.

  16854   Mon May 16 10:49:01 2022 AnchalUpdateDAQDAQ troubleshooting

[Anchal, Paco, JC]

Thanks Chris for the fix. We are able to access the testpoints now but we started facing another issue this morning, not sure how it is related to what you did.

  • The C1:LSC-TRX_OUT and C1:LSC-TRY_OUT channels are stuck to zero value.
  • These were the channels we used until last friday to align the interferometer.
  • These channels are routed through the c1rfm FE model (Reflected Memory model is the name, I think). These channels carry the IR transmission photodiode monitors at the two ends of the interferometer, where they are first logged into the local FEs as C1:SUS-ETMX_TRX and C1:SUS-ETMY_TRY .
  • These channels are then fed to C1:SCX-RFM_TRX -> C1:RFM_TRX -> C1:RFM-LSC_TRX -> C1:LSC-TRX and similar for Y side.
  • We are able to see channels in the end FE filtermodule testpoints (C1:SUS-ETMX_TRX_OUT & C1:SUS-ETMY_TRY_OUT)
  • However, we are unable to see the same signal in c1rfm filter module testpoints like C1:RFM_TRX_IN1, C1:RFM_TRY_IN1 etc
  • There is an IPC error shown in CDS FE status screen for c1rfm in c1sus. But we remember seeing this red for a long time and have been ignoring it so far as everything was working regardless.

The steps we have tried to fix this are:

  • Restart all the FE models in c1lsc, c1sus, and c1ioo (without restarting the computers themselves) , and then burt restore.
  • Restart all the FE models in c1iscex, and c1iscey (only c1iscey computer was restarted) , and then burt restore.

These above steps did not fix the issue. Since we have  the testpoints (C1:SUS-ETMX_TRX_OUT & C1:SUS-ETMY_TRY_OUT) for now to monitor the transmission levels, we are going ahead with our upgrade work without resovling this issue. Please let us know if you have any insights.

  16855   Mon May 16 12:59:27 2022 ChrisUpdateDAQDAQ troubleshooting

It looks like the RFM problem started a little after 2am on Saturday morning (attachment 1). It’s subsequent to what I did, but during a time of no apparent activity, either by me or others.

The pattern of errors on c1rfm (attachment 2) looks very much like this one previously reported by Gautam (errors on all IRFM0 ipcs). Maybe the fix described in Koji’s followup will work again (involving hard reboots).

  16856   Mon May 16 13:22:59 2022 yutaUpdateBHDREFL and AS paths aligned at AP table

After Xarm and Yarm were aligned by Anchal et al, I aligned AS and REFL path in the AP table.
REFL path was alreasy almost perfectly aligned.

REFL path
 -REFL beam centered on the REFL camera
 -Aligned so that REFL55 and REFL33 RFPDs give maximum analog DC outputs when ITMY was misaligned to avoid MICH fringe
 -Aligned so that REFL11 give maximum C1:LSC-REFL11_I_ERR (analog DC output on REFL11 RFPD seemed to be not working)

AS path
 -AS beam centered on the AS camera. AS beam seems to be clipped at right side when you see at the viewport from -Y side.
 -Aligned so that AS55 give maximum C1:LSC-ASDC_OUT16 (analog DC output on AS55 RFPD seemed to be not working)
 -Aligned so that AS110 give maximum analog DC output

  16857   Mon May 16 14:46:35 2022 TommyUpdateElectronicsRFSoC MTS Work

We followed the manual's guide for setting up MTS to sync on external signal. In the xrfdc package, we update the RFdc class to have RunMTS, SysRefEnable, and SysRefDisable functions as prescribed on page 180 of the manual. Then, we attempted to run the new functions in the notebook and read the DAC signal outputs on an oscilloscope. The DACs were not synced. We were also unable to get FIFOlatency readings. 

  16858   Mon May 16 16:13:01 2022 YehonathanUpdateBHDInitial BHD modeling: Damped suspension model

I was finally able to set up a stable suspension model with the help of Yuta and I'm now ready to start doing some MICH noise budgeting with BHD readout. (Tip: turns out that in the zpk function in Matlab you should multiply the poles and zeros by -2*pi to match the zpk TFs in Foton)

I copied all the filters from the suspension MEDM screens into a Matlab. Those filters were concatenated with a single pendulum suspension TF with poles at [0.05e-1+1i, 0.05e-1-1i] and a gain of 4 N/kg.

I multiplied the OLTF with the real gains at the DAC/DAC/OSEMs/Coil Driver and Coils. I ignore whitening/dewhitening for now. The OLTF was calculated with no additional ad-hoc gain.

Attachment 1 shows the calculated open-loop transfer function.

Attachment 2 shows OLTF of ETMY measured last week.

Attachment 3 shows the step and impulse responses of the closed-loop system.

 

 

  16859   Mon May 16 19:14:17 2022 AnchalUpdateBHDCamera set on AS path and BHDBS output path

[Anchal, Paco, Yuta]

  • We aligned AS path avoiding any clipping to the AP table where we setup a camera with a lens.
    • To do this we had to move AS6 in North direction for ~1cm.
    • The Injection table was imbalanced by this move to drop the IMC transmission to half.
    • We did not balance the table again, we steered the input mirror to reach to 1000 counts (out of 1200 nominal) and then used WFS loop to get to the last bit.
    • The input to the arm cavities did not change much, XARM was still flashing to 0.8 max height and YARM to 0.2. We recovered these easily using the cavity mirror pair.
  • We aligned the LO beam to be spatially matched on BHDBS with AS path.
    • The LO beam was steered to roughly overlap with the AS beam outputs on the BHDBS.
    • However, the LO beam size is very large and diverges after LO4.
    • According to 40m/15379, the 0.15m ROC of LO4 right after the beam waist is supposed to collimate the beam to a 522 um waist.
    • We confirmed that LO4 is marked as a 0.15m ROC mirror on its edge and the HR coating is facing the incident beam.
      • Conjecture (AG): The coating was applied to the flat side of the optic instead of the curved side.
      • This would explain why the beam is continuing to diverge after reflecting from LO4, and diverging fast.
    • We need to fix this issue before pumping down otherwise the mode matching would be too poor in BHDBS to have any meaningful results.
  • The output of BHDBS was steered out and a GigE camera is set up to see this path.
    • The camera is set to see the transmitted AS beam from BHD BS (and reflected LO beam).
    • But the camera is unable to see any LO beam due to large divergence.
    • The LO beam essentially disappears after ~30 cm from the BHDBS.

 

  16860   Tue May 17 18:43:38 2022 AnchalUpdateBHDPlaced SRM in ITMY Chamber

[Anchal, Paco, Yuta]

SRM Placement

  • SRM was moved from its parked location to the nominal position in the ITMY chamber.
  • This imbalanced the table a lot as all SOS towers ended up on the south side of the table.
  • I needed additionally three SOS tower side walls to recover the balance of the table.
    • I initially tried to use a level meter on my phone which claimed to have 0.1 degrees of accuracy. But it turned out to be a bad idea.
    • Eventually, I used the spirit bubble level meter we have, along with the OSEM values of ITMY, AS1, and AS4.
  • At the end, the table is balanced as it was before, all SOS are damping usually.

SRM Sat Amp Box setup

  • SRM Gold Box Sat Amp was found near the BS chamber.
  • This box was moved to the ITMY chamber.
  • The new flange on the East end was marked earlier for SRM. This flange on the vacuum side was connected with new in-vacuum blue ribbon cables.
  • We had previously moved the cable post for SRM (40m/16849) behind AS2. This cable post is connected to the old in-vacuum cable.
  • It would have changed the table balance to remove this cable post and connect new in-vacuum cables to it, so we decided to do this in the next vent when we put the BHD board on the table.
  • For now, we connected the old in-vacuum cable to the new in-vacuum blue ribbon cables inside.
    • Note, that the old in-vacuum cable has a gender flipping section which also mirrors the pin layout.
    • We installed pin mirroring cables on the outside between the Sat Amp Box and the vacuum flange to revert back the additional mirroring.
    • However it happened, now the Sat Amp Box is working, with all OSEMs and coils alive.
  • One peculiarity we found was that the SRM face OSEMs have only about 250-300 um of range, which is roughly 3 times less than the other OSEMs in other SOSs.
  • SRM side OSEM however behaves normally.
  • After installment, at the free-hanging state, SRM LL OSEM is saturated (too bright) and other face OSEMs are close to total brightness state.
  • We'll first put the alignment offsets to get the SRM perpendicular to the beam coming from SR2 and then center the OSEMs in this tiny range.
  • The low OSEM range could be due to improper biasing from the Sat Amp Box. Hopefully, with new electronics, this issue would go away in future.
  16861   Wed May 18 08:30:29 2022 PacoUpdateBHDSRM OpLev

[Paco]

The SRM Oplev injection and detection paths interfere heavily with the POY11. Due to the limited optical access, I suggest we try steering POYM1 YAW and adapting the RFPD path accordingly.

  16862   Wed May 18 09:02:52 2022 AnchalUpdateBHDWFS1 PD centered

I centered WFS1 PD so that IMC WFS Servo does not go out of range.

 

  16863   Wed May 18 17:23:15 2022 AnchalUpdateBHDPlaced PRM in BS Chamber

[Anchal, Paco, Yuta, JC]

SRM Oplev setup

  • We setup SRM oplev path for the aligned position of SRM.
  • This was bit hard, because the return beam was following almost the same path as the input beam, and the return beam had become about 1 cm in diameter.
  • We replaced one of the in-air steering mirror of SRM op-lev input beam with a 1 inch BS on a non-steeerable mount.
  • The returning oplev beam is picked at transmission from this BS.
  • Note: we are not sure if this BS is actually coated for IR or Visible. We couldn't find a visible BS in the lab. We should order a 2 in diameter visible BS to be placed in this position.
  • Half of the input beam would be used for PRM Oplev input.
  • The returning beam was focused with a 100mm focal length lens. Again, this lens is not verified to be for visible wavelength. We think it might have an AR coating for IR. We should get a visible lens for this position also.

PRM Placement

  • PRM placed in nominal position + 2 cm, East.
  • Currently, PRM SOS tower is blocking BS oplev input beam, this needs to be adjusted.
  • Installed PRMOL at nominal position + 2 cm East (to clear path from TT2)
  • I balanced the table succesfully, first using spirit bubble level and then OSEM levels of BS, SR2, PR3 and LO2.
    • Note, that we need to adjust OSEM positions in many of these SOS before pumping down.
  • Input beam from TT2 is going through center of PRM but the reflction is not coming back from PR2, maybe it is missing PR2 or PR2 alignment needs to be adjusted.
  16864   Thu May 19 08:51:40 2022 PacoUpdateBHDSRM OpLev

[Paco, Ian]

After agreement from Yuta/Anchal, I moved POYM1 yaw to clear the aforementioned path, and Ian restored the POY11 RFPD path. The demodulation phase might need to be corrected afterwards, before any lockign attempts.

Quote:

[Paco]

The SRM Oplev injection and detection paths interfere heavily with the POY11. Due to the limited optical access, I suggest we try steering POYM1 YAW and adapting the RFPD path accordingly.

 

  16865   Thu May 19 18:56:08 2022 yutaUpdateBHDCurrent OSEM sensor values with all the suspensions aligned

Current OSEM sensor values with all the suspensions aligned are attached.
For 'BS','ITMX','ETMX','ITMY','ETMY','PRM','SRM','LO1','LO2', the ones out of the range [200,800] are marked, and for 'PR2','PR3','SR2','AS1','AS4', the ones out of the range [6000,24000] are marked.

  16866   Thu May 19 19:05:59 2022 AnchalUpdateBHDBS Chamber all work finished, BHD path setup

[Anchal, Paco, Yuta]

BS Oplev Path

  • The changed position of PRM (40m/16863) meant that BS oplev path is getting clipped by the PRM SOS tower.
  • We had to move BSOL ~ 16 cm North and ~ 1.7 cm East.
  • This means that the BS Oplev input beam is now coming behind TT2 instead of infront of it.
  • We also had to align the beam such that input and returning beam are colinear.
  • This meant we, had to change the mount of the upstream beamsplitter in the in-air table so that we can use that for separating the return beam.
  • Again, we should order 2 inc visible BS for this path.
  • Half of the return beam is making its way all the way back to the laser head. I'm not sure if that can be an issue for our oplev loops.
  • We kept the SRM Oplev path same using irises on the table.

PRM Oplev

  • Again, due to changed position of PRM and BS Oplev, it became very hard to setup oplev for PRM.
  • We found a special position which allows us to catch returning beam through the center of the window.
    • But this returning beam is not prompt reflection from PRM, it is reflection of the HR surface.
    • We are hitting about ~5 mm from the edge of PRMOL mirror (because we cannot move the mirror anymore south to avoid clipping BS and SRM input oplev beams)
    • We put in a 1.1m focal length lens in the input beam to narrow the beam on PRMOL so that it doesn't clip
  • We did not put any lens for the return beam. The sensitivity of this oplev might be low due to slighlty bigger beam on the QPD than others (SRM, BS). We can revisit and insert a lens later if required.

Interferometer alignment and PRM alignment

  • The work on BS table did not change the table balance much. We got back the alignment pretty much instantly.
  • We were able to maximize the arm transmissions.
  • Then we used a beam card with hole to check for reflection from PRM and used PRM (mostly pitch correction) to get the return beam back in same way.
  • This recovered REFL beam on the camera. We used REFLDC signal to align PRM better and maximized it.
  • We centered BS, SRM and PRM oplevs after this point.

LO beam mode correction and spatial overlap

  • We tried changing the distance between LO3 and LO4 to get a better output LO beam.
  • We also tried to swap the LO4 mirror with the spare mirror but we had the same result.
  • Eventually, we decided to move LO3 back to East and LO4 to the west edge of the table. This made the beam sizes comparable.
    • Future exercise: We think that LO1 or LO2 might be significantly off-spec in their ROCs which might cause this issue.
    • We should rerun the calculations with the ROC values of LO1 and LO2 written in the datasheets and figure out the correct LO3-LO4 length required.
    • We can make this change in the next vent if required.
  • After the beam sizes were looking approximately similar but more iterations of changing length and realigning are required.

Remaining tasks before pumpdown

  • Push/pull too bright/dark OSEMs in the SOSs (40m/16865).
  • Finish LO beam mode correction and spatial overlap.
  • Center all oplevs, note all beam positions on camera, and note down all DC PD values at proper alignment.
  16867   Fri May 20 12:42:23 2022 TegaUpdateVACDoor installation on the end stations

[JC, Tega, Chub]

Today we installed the 200 lbs doors on the end station chambers.

  16868   Fri May 20 20:03:48 2022 PacoUpdateBHDITMY chamber work finished - LO and AS overlapped

[Paco, Anchal, Yuta]

Today, in short we:

  • Recovered alignment of arm cavities, PRC (only ITMX aligned), and then altogether with SRM and PRM aligned to maximize all DCPD levels (AS, POP, REFL, TRX, TRY), but SRC was not flashing and the SRM yaw alignment slider was around its max value, so after recording beam positions on cameras Anchal went into the BS chamber and helped steer the SRC alignment using a combination of SRM, SR2 and AS1. After this every beam was nominally aligned except for LO and AS, which remained to be mode matched.
  • Mode matched LO3-LO4 by hand -- cheeky -- from the ITMY chamber, the final separation between these two mirrors grew by almost 3 inches with respect to the design (!!!) but the LO and AS beams came out nicely. The canonical path used for the steering was LO path, and then we overlapped the beams with the help of a gige basler camera and a couple of DCPDs (Thorlabs).
  • Yuta and Paco started running final checks in preparation for Monday (pumpdown). We aligned the IFO, but noted that using Restore/Misalign sometimes results in hysteresis.. so it is not very reliable for fine alignment modes. Then we optimized DC levels, centered all oplevs, and tweaked Green input alignment on XARM and YARM. The XARM was maximized, but in YARM we could still not get high TEM-00 flashing ...
    • Unfortunately, we discovered a slight clipping of the GTRY beam through PR3 which could mean the current alignment (pointing) is not hitting PR3 center optimally.
  • Attached are the screenshot of current aligned state after the work tonight, with oplevs centered, and the OSEM sensor values.

ELOG V3.1.3-