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ID Date Authorup Type Category Subject
  16728   Tue Mar 15 14:10:41 2022 AnchalSummaryCDSc1su2 model remade, reinstalled, restarted after the update

I have restarted c1su2 model with the connections of Run Acquire switch to analog filters on coil drivers. Following steps were taken:

First ssh to c1sus2 and then:

controls@c1sus2:~ 0$ rtcds make c1su2
buildd: /opt/rtcds/caltech/c1/rtbuild/release
### building c1su2...
Cleaning c1su2...
Parsing the model c1su2...
Building EPICS sequencers...
Building front-end Linux kernel module c1su2...
RCG source code directory:
The following files were used for this build:

Successfully compiled c1su2
Compile Warnings, found in c1su2_warnings.log:
WARNING  *********** No connection to subsystem output named  SUS_DAC1_12  
WARNING  *********** No connection to subsystem output named  SUS_DAC1_13  
WARNING  *********** No connection to subsystem output named  SUS_DAC1_14  
WARNING  *********** No connection to subsystem output named  SUS_DAC1_15  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_7  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_8  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_9  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_10  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_11  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_12  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_13  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_14  
WARNING  *********** No connection to subsystem output named  SUS_DAC2_15  
controls@c1sus2:~ 0$ rtcds install c1su2
buildd: /opt/rtcds/caltech/c1/rtbuild/release
### installing c1su2...
Installing system=c1su2 site=caltech ifo=C1,c1
Installing /opt/rtcds/caltech/c1/chans/C1SU2.txt
Installing /opt/rtcds/caltech/c1/target/c1su2/c1su2epics
Installing /opt/rtcds/caltech/c1/target/c1su2
Installing start and stop scripts
Performing install-daq
Updating testpoint.par config file
/opt/rtcds/rtscore/branches/branch-3.4/src/epics/util/updateTestpointPar.pl -par_file=/opt/rtcds/caltech/c1/target/gds/param/archive/testpoint_220315_135808.par -gds_node=26 -site_letter=C -system=c1su2 -host=c1sus2
Installing GDS node 26 configuration file
Installing auto-generated DAQ configuration file
Installing Epics MEDM screens
Running post-build script

/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-AS1_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS1_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-AS1_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS1_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-AS1_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS1_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-AS4_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS4_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-AS4_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS4_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-AS4_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_AS4_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-LO1_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO1_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-LO1_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO1_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-LO1_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO1_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-LO2_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO2_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-LO2_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO2_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-LO2_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_LO2_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-PR2_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR2_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-PR2_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR2_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-PR2_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR2_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-PR3_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR3_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-PR3_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR3_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-PR3_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_PR3_TO_COIL_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 4 5 C1:SUS-SR2_INMATRIX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_SR2_INMATRIX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 2 4 C1:SUS-SR2_LOCKIN_INMTRX > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_SR2_LOCKIN_INMTRX_KB.adl
/opt/rtcds/userapps/release/cds/common/scripts/generate_KisselButton.py 5 6 C1:SUS-SR2_TO_COIL --fi > /opt/rtcds/caltech/c1/medm/c1su2/C1SUS_SR2_TO_COIL_KB.adl
safe.snap exists
controls@c1sus2:~ 0$

Then on rossa, run activateSUS2DQ.py which creates a file C1SU2.ini.NEW. Remove old backup file C1SU2.ini.bak, rename C1SU2.ini to C1SU2.ini.bak and rename C1SU2.ini.NEW to C1SU2.ini:

~> cd /opt/rtcds/caltech/c1/chans/daq/
daq>python2 activateSUS2DQ.py 
daq>rm C1SU2.ini.bak
daq>mv C1SU2.ini C1SU2.ini.bak
daq>mv C1SU2.ini.NEW C1SU2.ini

Then ssh back to c1sus2 and restart the rtcds model:

controls@c1sus2:~ 0$ rtcds restart c1su2
### stopping c1su2...
### starting c1su2...
c1su2epics: no process found
Number of ADC cards on bus = 2
Number of DAC16 cards on bus = 3
Number of DAC18 cards on bus = 0
Number of DAC20 cards on bus = 0
Specified filename iocC1.log does not exist.
c1su2epics C1 IOC Server started
c1su2 RT ready in 4
awg_server Version $Id$
channel_client Version $Id$
testpoint_server Version $Id$
/opt/rtcds/caltech/c1/target/gds/bin/awgtpman -s c1su2 -l /opt/rtcds/caltech/c1/target/gds/awgtpman_logs/c1su2.log started on host c1sus2 hostid ffffffffa8c05771 
awgtpman Version $Id$
controls@c1sus2:~ 0$

Then restart daqd services from rossa and burtrestore to latest snap of c1su2epics.snap:

daq>telnet fb 8083
Connected to fb.martian.
Escape character is '^]'.
daqd> shutdown
Connection closed by foreign host.
>burtwb -f /opt/rtcds/caltech/c1/burt/autoburt/latest/c1su2epics.snap -l /tmp/controls_1220315_140755_0.write.log -o /tmp/controls_1220315_140755_0.nowrite.snap -v <

All suspensions are back online and everything is same as before now. Will test later the Run/Acquire switch functionality.

  16729   Tue Mar 15 18:42:37 2022 AnchalSummaryBHDPart IX of BHR upgrade - AS1 resuspended and OSEMs tuned



  16730   Tue Mar 15 18:45:12 2022 AnchalSummaryBHDPart X of BHR upgrade - BHDBS Path setup

[Paco, Anchal]

BS Chamber work

  • ASL was positioned in nominal place.
  • PR3 was moved to its nominal place from temprorary position.
  • BS Table was rebalanced
  • Earthquake stops were removed from all SOS from BS table (LO2, SR2, BS, PR3)

ITMY Chamber work

  • AS2, AS3, LO3, LO4, and BHDBS were positioned in the nominal place.
  • AS1 was moved to its nominal place from temporary position.
  • ITMY tbale was rebalanced
  • Earthquake stops were removed from all SOS from ITMY table (AS1, AS4, ITMY)
  16733   Thu Mar 17 17:23:22 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment

[Anchal, Yehonathan] (on Y Arm)

We first checked if the PZT mirrors M1 and M2 can be controlled. They indeed show no motion even after being connected with a power supply. So green injection path can not be aligned using cds controls right now.

We also noticed that all ETMY slow controls and monitors are offline. That's because the electronics upgrade did not include acromag chassis. This means that the DC bias adjustment is not accessible for ETMY.

Alignment work:

  • We first aligned the green injection beam to cross two irises in the injection path to ETMY chamber.
  • Then I (Anchal) went inside the ITMY chamber to find the green light. Yehonathan controlled the injection path while I gave feedback from ITMY side. We aligned injection path to get the beam near center of ITMY.
  • Then I aligned ITMY through sitemap>IFO>Align to get counter propagating reflection near the ITMY side.
  • We were able to see reflection from ETMY hitting the beam tube.
  • Since DC alignment controls of ETMY are not accessible, we used the Alignment offset in rtcds model which puts dc offset in the coil driver to get the reflected beam from ETMY to come to ITMY table, about 1 inch above the table and about 3 inch south of ITMY SOS.
  • But we got limitted by the DAC overflow on ETMY at this point. Several back and forth attempts to relief ETMY were unsuccesful.

Possible issues:

  • We think having the HV coil driver set up for ETMY is important for this alignment work if not essential. The coil drivers of ETMY are near saturation.
  • We also think that addition of two new suspensions in ITMY table and then counter weights to balance the table, has depressed table height slightly. We need to work out how to change injection path height and angle accordingly.

[Paco, Ian] (on X Arm)


  16734   Thu Mar 17 19:12:44 2022 AnchalSummaryCDSc1auxey1 slow controls acromag chassis installed, not powered

[Anchal, Tega]

We installed c1auxey1 computer and the acromag chassis in 1Y4. The computer has been configured properly for nfs mounts to happen and we have initialized a git repo for /cvs/cds/caltech/target/c1auxey1 directory which stores all files for running modbusIOC service on this computer. We connected 18V power source but have not connected the 24V power yet  as we need to make a new connector for it. Going on what Koji recommended, we'll connect the 24V power input to 18 V strip as well as the acromags can run on that voltage too.

  16737   Fri Mar 18 19:10:51 2022 AnchalSummaryCDSc1auxey1 slow controls issues

I started the modbusIOC service on c1auxey1 and added PD variance channels for UR and SD as well.  There are unfortunately two issues here:

  • The enable monitors are reading NOT of what they should read. The optical isolator circuit might need to be changed.
  • ETMY is not damping now. This is strange and was seen in the use to other acromag chassis as well where AS4 and PR2 are unable to damp. This is weird since the acromag chassis are not part of the damping loop, maybe it is a coincidence. Next time we should check if we still have this issue when acromag chassis is disconnected from ETMY.


  16738   Mon Mar 21 14:22:52 2022 AnchalUpdateSUSETMY Alignmnet offsets needed to be changed

I'm not sure why but the PIT and YAW offset values of +2725 and -2341 were not sufficient for the reflected OPLEV beam to reach the OPLEV QPD. I had to change the C1:SUS-ETMY_PIT_OFFSET to 5641 and C1:SUS-ETMY_YAW_OFFSET to -4820 to come back to center of the OPLEV QPD. We aligned the Oplevs to center before venting, so hopefully this is our desired ETMY position.

On another note, the issue of ETMY unable to damp was simple. The alignment offsets were on to begin with with values above 1000. This meant that whenever we enabled coil output, ETMY would necessarily get a kick. All I had to do was keep alignment offsets off before starting the damping and slowly increase the alignment offsets to desired position.


- This modification allowed me to align the oplev spot to the center of the QPD. C1:SUS-ETMY_PIT_OFFSET and C1:SUS-ETMY_YAW_OFFSE are +2725 (8%FS) and -2341 (7%FS), respectively.

  16740   Mon Mar 21 18:24:07 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Tega]

We did the following alignment steps on Yarm today:

  • We aligned the green beam going into the ETMY chamber to the three irises on the path.
  • We aligned ETMY to get counter-propagating prompt reflection from ETMY.
  • We were able to see light in the reflection photodiode for the green PDH loop.
  • Then we went to ITMY chamber and checked where the beam is coming to. It was coming very low in height.
  • We walked the beam on the end to get it near the center of ITMY.
  • Then we changed the ETMY alignment again to get back the reflection beam on the reflection photodiode.
  • Then we went again to ITMY chamber and changed the ITMY alignment to get counter-propagating reflection from ITMY.

After this, we came back to the control room. One peculiar thing to note is that the C1:LS-Y_REFL_DC_OUT channel is inverted i.e. it is showing negative values for the reflection DC voltage. On this signal, we see a little bit higher-order mode flashing but it is not bright enough to be seen on the face camera of the suspension. We'll continue aligning the cavity using CDS now to get TEM00 mode.

After trying for a bit, we were able to get flash of about 2000 counts which is about 16% of the max value of 12200 counts. We adjusted the ITMY angular position using the IFO_ALIGN screen but used the OPTICAL_ALIGN offset screen to adjust the angular position of ETMY. The pitch and yaw values for ITMY are 1.0360 and -0.260 respectively whereas the pitch and yaw values for ETMY are 5664.0 and -4937.0 respectively. 

  16741   Mon Mar 21 18:42:06 2022 AnchalSummaryCDSc1auxey1 slow controls issues

Another issue, Green Y Shutter can not be controlled with the EPICS controls right now. This needs to be investigated.

  16742   Thu Mar 24 19:20:28 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Paco]

Uneloged: yesterday, Paco and Ian tried locking the green laser on Yend to the Y-arm. Nothing noteworthy happened, no luck.

  • Started with aligning the green injection to the Iris on table (it was misaligned) and getting it on the ITMY center.
  • Then we realized that the beam is going through the focusing leans very offceter. This makes the beam warped and deflected inside that needs to be corrected by mirrors.
  • So we decided to adjust the lens position first.
  • We realized that lens position is hard to adjust along with keeping the beam hiting ITMY.
  • So, we decided to remove the lens first and just align the green beam directly with the Iris on the table and the ITMY center. The beam became as big as ITMY when it reached there without the lens in path. We aligned it to fall on the mirror.
  • Then we placed the lens back so that the beam goes through the center of the lens.
  • Then we aligned ETMY to get the reflection back to the reflection PD.
  • But then when we checked the beam at ITMY again, it was severely missing ITMY. The possible reason is that ETMY is a diverging lens for the beam as well and changing its position changed the beam direction in the beam tube.
  • We decided to do another iteration of lens positioning with the new ETMY position. So same steps, removed lens, aligned beam with iris and ITMY, placed back the lens, aligned ETMY again to get reflection back on the PD.
  • This time the beam was still reaching ITMY. So we were glad that our iterations converged in 2 repititions.
  • Then we aligned ITMY to get counter propagating beam.
  • At the end of this alignment:
    • We see dips in relfection photodiode counts from 12200 to 9500.
    • The ETMY oplev is partially out of range (only 1 of the quadrant seeing light) but that could be because we changed the lens position. So Oplev servo is off.
  • We confirmed that the PDH servo is properly connected and loop is on. But we see no HOM catching lock for YARM even after us doing about 10 min search with ITMY-ETMY alignments.
  • We are leaving things as it is. We'll continue trying to align the cavity tomorrow. Everyone is welcome to try as long as they restore the positions of the optics to a good state at the end.



  16743   Fri Mar 25 11:39:14 2022 AnchalUpdateSUSETMY SUS Electronics Replacement - Questions

After Ian updated the cts2um filters for OSEM, shouldn't the damping gains be increased back by factor of 10 to previos values? Was the damping gain for SIDE ever changed? we found it at 250.

Can you explain why gain_offset filter was required and why this wasn't done for the side coil?


I updated the gain of the ct2um filter on the OSEMS for ETMY and decreased their gain by a factor of 9 from 0.36 to 0.04.

I added a filter called "gain_offset" to all the coils except for side and added a gain of 0.48.

together these should negate the added gain from the electronics replacement of the ETMY


  16744   Fri Mar 25 18:20:28 2022 AnchalSummaryBHDPart IIa of BHR upgrade - Green laser alignment on Yarm

[Anchal, Paco, Shruti]

  • Today we found out that the laser controller at the Yend had it's inputs disconnected for the FAST PZT input and the Slow temperature control input. The cables were also not labeled that were lying nearby.
  • I tracked the cables and connected the Fast input adn the slow input.
  • We then adjusted the temperature slider to go to previously marked laser crystal temperature of 40.1 degrees celsius. But we could not find the the beatnote of Y end IR with teh Main laser IR.
  • We scanned the laser crystal temeprature until we could see a beatntoe with the main IR laser and stopped in that region.
  • Then we continued looking for flashing and HOM, but no luck.
  • It was interesting that when the PDH loop was closed, we saw fluctuations in relfection photodiode DC value, but not so much when the loop was not closed.
  • We tried flipping the sign of the loop with no luck and we tried changing the gain of the loop as well, but no luck.
  • The behavior of this Yend laser and its controller is still suspicious to us. When the loop is closed, the PZT feedback signal should not cause a change in amplitude of the light so much as we see it.
  • Also the fact that when loop is clsoed we do not see signs of flashing in the reflection photodiode is interesting. If anyone has any ideas, that would be good.
  16756   Mon Apr 4 17:03:47 2022 AnchalSummaryCDSc1susaux2 slow controls acromag chassis fixed and installed

[Anchal, JC, Ian, Paco]

We have now fixed all issues with the PD mons of c1susaux2 chassis. The slow channels are now reading same values as the fast channels and there is no arbitrary offset. The binary channels are all working now except for LO2 UL which keeps showing ENABLE OFF. This was an issue earlier on LO1 UR and it magically disappeared and now is on LO2. I think the optical isolators aren't very robust. But anyways, now our watchdog system is fully functional for all BHD suspended optics.

  16757   Tue Apr 5 18:15:06 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

[Paco, Anchal, Ian, JC]

We attempted the alignment of IR beam into the arm cavities. We used PR2 and PR3 (moved manually as well as using cdsutils) and got the YAW aligned pretty good on both X and Y directions. PIT alignment however turned out to be much harder to align. PR2 PR3 didn't have much range, so we zeroed there offset and tried to use TT1, TT2, MMT1, and MMT2 to align the PIT but it would get clipped before reaching BS table if we were to correct for PIT misalignment happening downstream. We concluded that the issue is that one of the PR2, PR3 mirrors have too much PIT offset in equilibrium position. We have requested Koji to change the output resistors in the coil drivers of PR2 and PR3 so that we can correct for the PIT offset in them directly using the coils and reduce load on upstream optics. We have tweaked TT1, TT2, MMT1, and MMT2 positions today, so we do not have the previous reference anymore.

  16759   Wed Apr 6 12:03:51 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Yarm

[Anchal, Paco]

After Koji reduced the output resistors on PR2/PR3 coil drivers, we got much better actuation range. We aligned TT1 TT2 again to get beam centered on PR2 and PR3. Then we used only PR2 and PR3 to do the input beam alignment to Y arm cavity. Using access in ETMY chamber, we aligned the input beam parallel to cavity axis. Slight changes were required in ETMY alignment offsets to get first roundtrip in same spot on ITMY. remaining alignment is finer and needs to be done with a help of a reflection photodiode and cameras in the control room. Immediate next step is to setup POY path for locking the Yarm with IR.

Side note: Because of the large PIT correction required in PR3, we found that our upper OSEMs were hitting totally bright limit and lower OSEMs were hitting totally dark limit on PR3. This also destablized our damping loops. We pushed the upper OSEMs slighlty and pulled back the lower OSEMs slightly to get the PD signal in half shadow region again. This worked and our damping loops are stable again. However, we think we should repeat free swing test in future to diagonalize the input matrix for new OSEM positions.

  16762   Thu Apr 7 17:59:51 2022 AnchalSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Yarm

[Anchal, Paco, JC, Tega]

Today we have aligned the Yarm cavity for IR, with verified 1.5 roundtrips. We also placed following optics in the BS table.

  • POXM1 (installed earlier, not eloged)
  • SRMOL2
  • POYM1
  • SRMOL1
  • POYM2

We also cleared the in-air BS table of all previous optics. JC and Tega setup HeNe laser for Oplevs roughly for now. Tega also transported the POY RFPD from ITMY in-air table to the BS in-air table. We aligned the POY path to the table, but we had to move ITMY after that to get 2nd roundtrip in the arm cavity, which misaligned our POY path again. POY path would need to be modified tomorrow.


  16804   Fri Apr 22 12:09:51 2022 AnchalUpdateCoil DriversPlease update DCC pages

Nice. Please put this information on the DCC pages of the coil driver units. You'll find links to all the units in this document tree LIGO-E2100447. For each page, click on "Change Metadata" from the left panel and add the change made to the resistor (including the resistor name on PCB, previous and new value), and add a link to your previous elog post which has more details like photos, to "Notes and Changes", and upload an updated version of the circuit schematic by creating an annotation in the previous circuit schematic pdf. Every unit that has a serial number in the lab has a DCC page (if not, we should create one) where we should track all such hard changes.


  16805   Fri Apr 22 12:15:08 2022 AnchalUpdateBHDCable post installation

If someone gets time, let's put in all the cable posts and clean up our cable routing on the tables.


  16810   Mon Apr 25 16:57:57 2022 AnchalUpdateBHDCable post installation

[Anchal, Tega, JC]

We installed cable posts in ITMY, BS, and ITMX chambers for all the new suspensions. Now, there is no point where the OSEM connections are hanging freely.

In BS chamber, we installed one post for LO2 near the north edge of the table and another post for PR3 on the Western edge with the blue cable running around the table on the floor.

In ITMY chamber, we installed the cable post in between AS1 and AS4 with the blue cables running around the table on the floor. This is to ensure the useful part of the table remains empty for future and none of the OSEM cables are taught in air.


  16811   Mon Apr 25 17:24:06 2022 AnchalUpdateCDSDAQ still down

I investigated this issue today. At first, it seemed that only new suspension testpoints are inaccessible. I was able to use diaggui for a measurement on MC2. The DAQ network cable between 1X4 and 1Y1 was tied and is very taught now (we should relieve this as soon as possible, best solution is to lay down a longer cable over the bridge). My hypothesis is that the DAQ network might have broken while tying this cable and it probably did not come back since then.

The simplest solution would have been to restart c1su2 models. As I restarted those models though, I found that c1lsc and c1sus models failed. This is very unusual as c1su2 models are independent and share nothing with the other vertex models. So I had to restart all the FE computers eventually. But this did not solve the issue. Worse, now the DAQ isn't working for the vertex machiens as well.

Next step was to try restarting fb1 itself. We switched off all the FE computers, restarted fb1, stopped daqd_* processes, reloaded gpstime module, restarted open-mx, mx, nds and daqd_* process. But the mx.service failed to load with following error message:

● mx.service - LSB: starts MX driver for Myrinet card
   Loaded: loaded (/etc/init.d/mx)
   Active: failed (Result: exit-code) since Mon 2022-04-25 17:18:02 PDT; 1s ago
  Process: 4261 ExecStart=/etc/init.d/mx start (code=exited, status=1/FAILURE)

Apr 25 17:18:02 fb1 mx[4261]: Loading mx driver
Apr 25 17:18:02 fb1 mx[4261]: insmod: ERROR: could not insert module /opt/mx/sbin/mx_mcp.ko: File exists
Apr 25 17:18:02 fb1 mx[4261]: insmod: ERROR: could not insert module /opt/mx/sbin/mx_driver.ko: File exists
Apr 25 17:18:02 fb1 systemd[1]: mx.service: control process exited, code=exited status=1
Apr 25 17:18:02 fb1 systemd[1]: Failed to start LSB: starts MX driver for Myrinet card.
Apr 25 17:18:02 fb1 systemd[1]: Unit mx.service entered failed state.

(Ignore the timestamp above, I ran the command again to capture the error message.)

However, I was able to start all the FE models without any errors and daqd processes are also all running without showing any errors. Everything is green in CDS screen with no error messages. But the only thing still wrong is mx.service which is not running.

From my limited knowledge and experience, mx.service is a one-time script that mounts mx devices in /dev and loads the mx driver. I tried running the script /opt/mx/sbin/mx_start_stop :

controls@fb1:/opt/mx/sbin 1$ sudo ./mx_start_stop start
Loading mx driver
insmod: ERROR: could not insert module /opt/mx/sbin/mx_mcp.ko: File exists
insmod: ERROR: could not insert module /opt/mx/sbin/mx_driver.ko: File exists

This gave the same error. On searching little bit online, "insmod: ERROR; cound not insert module" error comes up when the kernel version of the driver doesnot match the Linux kernel (whatever that means!). Such deep issues should not appear out of nowhere in a previosuly perfectly runnig system. I'll check around more what changed in fb1, network cables etc.

  16815   Wed Apr 27 16:28:57 2022 AnchalSummaryBHDBHD Upgrade - Retreiving arm cavity alignment

[Anchal, Paco, JC]

We had to open ITMY, ETMY chamber doors to get the cavity aligned again. Once we did that, we regained cavity flashing and were able to align the input injection and cavity alignment to get transmission flashing to 1.0 (C1:LSC-TRY_OUT_DQ). JC later centered both ITMY and ETMY oplevs. The ITMY oplev had become completely out of range.

We also opened ITMX, ETMX chamber doors to get Xarm alignment. Again, it seems that ITMX had moved a lot due to cable post installation.

To be continued

  16816   Thu Apr 28 09:12:18 2022 AnchalUpdateBHDRestoring arm alignment

This would be a daily first task in the morning. We'll need to check the status of arm alignment and optimize it back to maximum every morning for the rest of the day's work.

Today, when I came, on openin gthe PSL shutter, IMC was aligned good, both arms were flashing but YARM maximum transmission count was around 0.7 (as opposed to 1 from yesterday) and XARM maximum transmission count was 0.5 (as opposed to 1 from yesterday). I did not change the input alignment to the interferometer. I only used ITMY-ETMY to regain flashing count of 1 on YARM and used BS and tehn ITMX-ETMX to regain flashing count of 0.9 to 1 in XARM.

Even thought the oplevs were centered yesterday, I found the oplev had drifted from the center and the optimal position also is different for all ooptics except EMTY and BS. It is worth nothign that in optimal position both PIT and YAW of ITMY and ITMX are off by 70-90 uradians and ETMX Pit oplev is off by 55 uradians.


  16817   Thu Apr 28 11:53:10 2022 AnchalSummaryBHDPOP_SM4 and POP_SM5 Assembly


I tried out this stack today and found some change of plans.

  • The attachment in elog 40m/16640 says to use 1/4-20 silver coated non-vented screws for joining BA2V to PLS-T238, however PLS-T238's bottom hole is a blind hole and is not vented. So we actually required <1 in long silver plated vented 1/4-20 cap screw for this purpose. Jordan and I were only able to find the correct length silver plated screw but it is not vented. So we decided to make a venting hole on the post from the side.
  • I had to use a 0.14" spacer as washer between PLS-T238 and BA1V. The 1" post shim that Koji got for this purpose had too small a hole in the center to let the 8-32 screw pass (I know, weird). but I think we had 3 spare 0.14" ad we bought 10 when we required 7, so we should be good.
  • The attachment in elog 40m/16640 also says to use 8-32 silver coated vented setscrew for joining TR-1.5 to LMR1V mount. I found one vented silver coated set screw nearby in the clean room but it turned out to be too long. Worse, I overtightened the setscrew when trying this connection which damaged the inner threads of one of the LMR1V. So we need to buy one more LMR1V (maybe an additional spare too) for future installation of OMC1R1/OMC2R1.
    • Then Jordan and I searched for a smaller silver coated and vented 8-32 setscrew but didn't find any. Jordan also noted that LMR1V is an aluminium mount and we should not use silver coated setscrew with it. Since the TR-1.5 mount is ok to be sacrificed if a cold weld happens, we'll just use an uncoated SS 8-32 setscrew to join TR-1.5 and LMR1V. We could not such vented setscrews, but we have plenty of non-vented once. So Jordan is going to make a venthole in TR1.5 top end as well. LMR1V already has a vent hole on its side.

tl,dr; Jordan is preparing PLS-T238 and TR-1.5 with venting holes and C&B and they would be ready by tomorrow. I have collected all other parts for assembly, still looking for the mirror but I know other lab members know where it is, so no big issue there.


The assemly of this mirror is complete. A slight change here as well, we were supposed to use the former POYM1 (Y1-2037-0) mirror for POP_SM5 but I could not find it. It was stored on the right most edge of the table (see 40m/16450), but it is not there anymore. I found another undocumented mirror on the flow bench on the left edge marked (2010 July: Y1-LW1-2037-UV-0-AR) which means this mirror has a wedge of 1 degree and an AR coating as well. We do not need or care about the wedge or AR coating, so we can use this mirror for POP_SM5. Please let me know if someone was saving this mirror for some other purpose.

I'll finish assembly of POP_SM4 tomorrow and install them in ITMX chamber and resurrect POP path.


Here is more detail of the POP_SM4 mount assembly.

It's a combination of BA2V + PLS-T238 + BA1V + TR-1.5 + LMR1V + Mirror: CM254-750-E03
Between BA1V and PLS-T238, we have to do a washer action to fix the post (8-32) with a 1/4-20 slot. Maybe we can use a 1" post shim from thorlabs/newport.
Otherwise, we should be able to fasten the other joints with silver-plated screws we already have/ordered.

I think TR-1.5 (and a shim) has not been given to Jordan for C&B. I'll take a look at these.


  16818   Thu Apr 28 17:45:53 2022 AnchalUpdateBHDPOX Beam issues

[Anchal, Paco]

We investigated the low power issue with POX11 photodiode.

  • We used a power meter to confirm that above 12 uW of power is reaching the ITMX oplev table.
  • But the power reaching the photodiode was only 3 uW, because the 2 steering mirrors used were discarding half of the light. These mirrors were taken from former POP setup and are probably BS or meant for different incidence angle/polarization.
  • We used flashlight to test that the photodiode gives a response, so it is not dead.
  • We also put in a db15 breakout board in line to the PD and confirmed that power input is correct, temperature is nominal, enable is ON, and DC out is responsive to flashlight.
  • So we decided to redo the path with Y1-45P 1inch mirrors. I found two such mirrors in the lab.
  • When setting up the path again, I realized that the beam shape is not even. I took a photo of the beam on the card (see attachment 1) and indeed the POX beam that is coming to the table is half clipped.
  • So tomorrow, we'll open the chamber and find out where this is happening. For now, I've setup a nominal path to the POX11 photodiode, but we'll tune it after we get a clear POX beam on the table.
  16819   Thu Apr 28 18:07:04 2022 AnchalUpdateBHDRestoring arm alignment at EOD

Restored arm algiment to get 0.8 max flashing on YARM and 1 max flashing on XARM. I had to move input alignment using TT2-PR3 pair and realign YARM cavity axis using ITMY-ETMY pair.

I would like to advertise this useful tool that I've been using for moving cavity axis or input beam direction. It's a simple code that makes your terminal kind of videogame area. It moves two optics together (either in same direction or opposite direction) by arrow key strokes (left, right for YAW, up, down for PIT). Since it moves two optics together, you actually control the cavity axis or input beam angle or position depening on the mode.


  16824   Mon May 2 17:51:30 2022 AnchalUpdateBHDPOX Beam aligned on RFPD, YARM locked

[Paco, Anchal]

We found that one of the Y1-1037-45P marked mirror that we used was actually curved. So we removed it and used a different Y1-1037-45P mirror, adjusted the position of the lens and got the beam to land on POX11 RFPD successfully.

Then in control room, we maximized the POX11_I_ERR PDH signal amplitude by changing C1:LSC-POX11_PHASE_R to 42.95 from -67.7. We kept the C1:LSC-POX11_PHASE_D same at 90. We were getting +/- 200 PDH signal on POX_I_ERR.

Then in our attempt to lock the XARM, when we ran the "Restore XARM (POX)" script, YARM locked!

We are not sure why the YARM locked, we might have gotten lucky today. So we ran ASS on YARM and got the transmission (TRY_OUT) stable at 1. The lock is very robust and retrievable.

Coming back to XARM, we realized that the transmission photodiode used for XARM was the low-gain QPD instead of the thorlabs high gain photodiode. The high-gain photodiode was outputing large negative counts for some reason. We went to the Xend to investigate and found that the high gain photodiode was disconnected for some reason. Does anyone know/remember why we disconnected this photodiode?

We connected the photodiode back and it seems to work normally. We changed the photodiode selection back to high gain photodiode for TRX and on 40 dB attenuation, we see flashing between 1.4 to 1.6. However, we were unable to lock the XARM. We tried changing the gain of the loop, played a little bit with the trigger levels etc but couldn't get it to lock. Next shift team, please try to lock XARM.


[Paco, Anchal, Yuta]

We opened the BSC and ITMX chamber in the morning (Friday) to investigate POX11 beam clipping. We immediately found that the POX11 beam was clipping by the recently installed cable posts, so luckily no major realingment had to be done after reinstalling the cable post in a better location.

Because we had the BSC open, we decided to steer the AS1 mirror to align the AS path from ITMY all the way to the vertex chamber.  Relatively small AS1 offsets (of ~ 2000 counts each) were added on PIT / YAW to center the beam on ASL (there is slight clipping along PIT, potentially because of the AS2 aperture. We then opened the vertex chamber and located the AS beam with relative ease. We decided to work on this chamber, since major changes propagate heavily downstream (simply changing the IMC pointing).

Anchal removed old optics from the vertex chamber and we installed the steering pair of mirrors for AS path. This changed the balance of the vertex table by a lot. By using the MC REFL camera beam spot we managed to coarsely balance the counterweights and recover the nominal IMC injection pointing. Simply reenabling the IMC autolocker gave us high transmission (~ 970 counts out of the typical 1200 these days).

The final IMC alignment was done by Anchal with delicate PIT motion on the input injection IMC miror to maximize the transmission (to our satisfaction, Anchal's motion was fine enough to keep the IMC locked). The end result was quite satisfying, as we recovered ~ 1200 counts of MC transmission.

Finally, we looked at the arm cavity transmission to see if we were lucky enough to see flashing. After not seeing it, we adjusted TT1 / TT2 to correct for any MMTT1 pitch adjustment needed after the vertex table rebalancing. Suprisingly, we didn't take too long and recovered the nominal arm cavity pointing after a little adjustment. We stopped here, but now the vertex table layout is final, and AS beam still needs to be aligned to the vertex in-air table.


  16826   Tue May 3 14:02:09 2022 AnchalSummaryBHDInstalled POP path in ITMX Chamber

[Anchal, JC]

I installed POP_SM4 and POP_SM5 in the ITMX chamber in the nominal positions. This must have affected the ITMX Oplev because I could see that one of the ITMX oplev beam was going through POP_SM5. It needs to be changed in order to follow the original plan. However, since POP_SM5 is a 1064 line mirror, it is transparent to the opleve beam, so maybe we can just use the ITMX oplev in the current fashion.

Next steps:

  • Get flashing back on the XARM.
  • Try to get the correct phase angle in POX11 so that we can lock XARM with IR too.
  • Inspect ITMX Oplev. The quadrant sum is low so maybe it needs adjustment in the in-ar table.
  • Check if ITMX oplev path needs to be adjusted inside the chamber.
  16829   Wed May 4 13:09:42 2022 AnchalUpdateBHDIMC table balanced again, IMC is locking, YARM is locking

[Paco, JC, Anchal]

We balanced the IMC table back again to point that got us 50% of nominal transmission from IMC. Then we tweaked the steering mirror for injection to IMC to get up to 90% of nominal transmission. Finally, we used WFS servo loop to get to the 100% nominal transmission from IMC. However, we found that the WFS loop has been compromised now. It eventually misaligns IMC if left running for a few minutes. This needs to be investigated and fixed.

Next steps:

  • Align X-arm cavity and regain flashing.
  • Fix the Oplev path for ITMX.
  • Tune POX11 phase angle to get an error signal with which we can lock the cavity.
  • Finish AS beam path setup.
  16832   Thu May 5 14:46:22 2022 AnchalUpdateBHDPOP beam height lowered, POP_SM4 raised

[Anchal, JC]

We first aligned the single arm cavity resonance for both arms to get maximum flashing. As we opened the chamber, I found that the POP beam was mostly hitting the POP_SM4 mirror but was clipping about 2 mm on the top edge.

I used TT2-PR3 to lower the injection beam angle and moved pairs of ITMY-ETMY, and ITMX-ETMX to recover as much flashing as I could in the both arms. Then, I moved PR2 in pitch from 49 to 71 to maximize the arm flashing again. After these steps, the POP beam was clearly within the POP_SM4 mirror but still in the upper half of the optic and there was maybe just a mm of clearance from the top edge. I decided to raise POP_SM4 mirror by 0.14" spacer. Now the beam is still in upper half of the mirror but has a good clearance from the edge.

The POP beam is coming outside in the in-air table at as a rising beam in the nominal path near the center of the window. This beam needs to be directed to the POP camera and RFPD on the far-side of the table.

Next steps:

  • In-air table work: Setup POP camera and RFPD.
  • In ITMX chamber, rotate ITMX Oplev mirror to clear the oplev beam off POP_SM5. Change oplev beam path outside accordingly.
  • Install green transmission from X-arm steering mirrors in BS chamber.
  • Install 4 steering mirrors in ITMY chamber at the two outputs of BHD BS to direct the beam outside.
  • Figure out POX11 rotation angle and get XARM locking as well.


  16835   Fri May 6 13:48:34 2022 AnchalUpdateBHDWFS loop instability fixed

[Yuta, Anchal]

We investigated why WFS loop wasn't working. It seemed like WFS1 PIT error signal has a huge offset which would push the loop to misalign all optics' PIT. So we did the following steps:

  • Cover the WFS with Aluminium foils. Run Sitemap>IOO>C1_IOO_WFS_MASTER>!Actions>Correct WFS DC offsets.
  • Then center the WFS beams on the QPDS while looking at C1:IOO-WFS1/2_PIT/YAW_DC channels.
  • Then Switch off WFS loop, Switch off Autolocker, toggler the PSL Shutter so that IMC unlocks and does not catch lock back, and tehn run Sitemap>IOO>C1_IOO_WFS_MASTER>!Actions>Correct WFS RF offsets.
  • The above script found significant changes required in WFS1 RF offsets. After this, we opened the shutter and WFS loops were working fine.
  16837   Mon May 9 18:43:03 2022 AnchalUpdateBHDITMX table layout corrected

As I went to correct the ITMX Oplev mirrors, I found that both mirrors were placed in very different positions than the design position. Part of the reason I think was to preserve outside oplev path, and party because a counterweight was in ITMXOL1 position. I had to do following steps to correct this:

  • I noted down level meter readings of the table before making any changes.
  • I removed the counter weight from near the center of the table.
  • I placed the Oplev mirrors in the nominal positions.
  • I placed the counter weight near previous position.
  • I moved a edge hanging counter weight to get back the level meter to its previous state coarsely.
  • Then I used dataviewer to find the previous OSEM PD monitor values and changed ITMX PIT and YAW to come closer to those PD values. And voila, I regained the flashing on Xarm. I nudged the ITMX pit and yaw bit more to maximize it.
  • I then went back to aligning the Oplevs properly.
  • Then I adjusted the POP mirrors to get the beam back through center of window. This was very tricky and took a lot of time.
  • Now the beam is going through near center and the oplev beams are far away enough from POP_SM5.
  • On the outside table, I noted the POP beam and the oplev beam. I corrected the pit of the returning beam to get the oplev beam at nominal height on outside table.

ITMX Sat Amp is flaky

[Anchal, Paco]

During the above work, i must have kicked the cable between the vacuum flange and the satellite amplifier box for ITMX. This disconnected all the OSEMs and Coils. We tried several things to debug this and finally found that nudging the connections on Sat Amp box brought the OSEMs and coils back online. Note that the connector was not partially out or in a state that obviously showed disconnection of the pins. I'm glad we are putting in new electronics soon for the vertex optics as well.

Next steps:

  • I showed Tega the returning oplev beam and the POP beam coming out of the ITMX chamber.
  • The Oplev beam paths need to be adjusted.
    • The ongoing beam steering mirror is blocking the returning beam, so the ongoing path needs to be changed.
    • First setup two irises to save ingoing path.
    • Then make space for the returning beam by changing the steering mirror positions.
    • Then recover the ingoing path to the center of irises.
    • Steer the returning beam to the QPD.
    • Then maximize the flashing on XARM and center the oplev to save this position.
  • POP beam needs to be directed to previous setup on far side of table.
    • The POP beam is coming out at the rising angle.
    • This is good for us if we do bit unconventional stuff and transfer the beam to other side of table at an elevated height. Given how close all the beams are coming out of the viewport, I think this is the best solution in terms of saving time.
    • Get the beam down to the old setup which was camera and photodiodes all aligned.



  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.
  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.

  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.
  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.
  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.
  16872   Tue May 24 15:21:13 2022 AnchalUpdateBHDFreeswing tests of new SOS started

I modified the script freeSwing.py to use damping loop output switches to free the optic instead of watchdog or coil output filters. This ensures that the free swing test is being done at the nominal position of the optic. I started tests for LO1, LO2, As2, As4, PR2, PR3, and SR2 in a tmux session names freeSwing on rossa.

Note: LO2 face OSEMs are hardly sensitive to any motion right now due to excessive pitch offset required for LO beam. We should relieve this offset to LO1 and rerun this test later.

  16899   Tue Jun 7 19:40:45 2022 AnchalUpdateSUSITMY changed output matrix to disable use of UL coil

Since UL coil actuation is lost, we modified the output matrix of ITMY to use only UR, LR and LL face coils for POS, PIT and YAW actuation. The output matrix was changed to following:

UL 0 0 0 0
UR 1 1 0 0
LL 1 0 1 0
LR 0 -1 -1 0
SIDE 0 0 0 1






After this change, the damping was still working as good as before. I took PIT to POS/PIT/YAW and YAW to POS/PIT/YAW coupling measurements by exciting C1:SUS-ITMY_ASCPIT[YAW]_EXC and seeing effect at C1:SUS-ITMY_SUS[POS/PIT/YAW]_IN1 when the damping loops were off. Attached are the results. We were able to reduce PIT to YAW and YAW to PIT coupling by 10 dB by this simple change in output matrix. More coil balancing or off-diagonal termsmight help more and should be attempted if required. The coupling to POS did not change much.

Note that attachment 1 shows transfer functions from excitation point to the DOF sensing inputs while attachment two looks at ratio of C1:SUS-ITMY_SUS[POS/PIT]_IN1 to C1:SUS-ITMY_SUSYAW_IN1 which is the actual quantity of interest. I didn't repeat the PIT measurement due to lack of time.

Also note that all such measurements are being recorded in our new measurements git repo. We'll populate this repo with diaggui template+data files as we do measurements.

  16913   Tue Jun 14 18:45:43 2022 AnchalUpdateSUSLO2 lower magnets are stuck in coil, won't come off

[Anchal, Yuta]

In the weekend, I ran a free swing test on all optics. During this test, LO2 magnets got stuck to the coil because LO2 PIT alignment was very high, making its lower OSEMs almost fully dark and upper OSEMs almost fully bright. Today we realized that LO2 is actually stuck and is not coming off even when we dither PIT alignment. We tried several ways but could not get this off. sad

Do we have any other method to get magnets off in vaccum?

It will be pretty bad if we try anything related to BHD with LO beam reflecting off a stuck mirror. Does anyone have any suggestions other than venting and fixing the issue?

  16915   Tue Jun 14 20:57:15 2022 AnchalUpdateASCYarm ASS working now

I finally got YARM AS to work today. It is hard to describe what worked, I did a lot of monkey business and some dirty offset measurements to create the ASS output matrix that gave results. Note that I still had to leave out ITMY PIT L error signal, but transmission was maximizing without it. The beam does not center fully on ITMY in Pit direction right now, but we'll mvoe on from this problem for now. Future people are welcome to try to make it work for this last remaining error signal as well.



  16925   Thu Jun 16 18:30:07 2022 AnchalUpdateSUSNew diagonalized input matrices applied

I used the same fre swing data to diagnolize input matrices of following optics:
MC1, MC2, MC3



For all these optics, the new input matrices worked well. Next step should be to take the local damping open loop transfer functions and standardize the loops to same UGF.

What didn't work:

  • The calculated input matrix for ITMX differed from existing matrix too much, including overall sign of rows POS and PIT. Even after correcting those signs, I was not able to get a good damping loop configuration. So I have committed the new matrix to the repo but have not implement it. More close analysis or another test might be required for this optic.
  • LO1, LO2, and ITMY were not analysed because their free swing test was not valid. LO1 and ITMY had non-working coils and LO2 was stuck during the test. We'll take another free swing test for these three optics (and possible ITMX) in near time.

All diagonalization results are present in https://git.ligo.org/40m/scripts/-/tree/main/SUS/InMatCalc

For looking at the results at this point, go to this commit: https://git.ligo.org/40m/scripts/-/tree/7ef6a47d1b2051a0732f46477624a9e625737fe8

  16931   Tue Jun 21 08:36:50 2022 AnchalUpdateSUSDiagonalized input matrices for LO1, freeSwing on ITMY and ITMX

Over the weekend, I ran freeSwing test with sequential kicks in specific DOFs for LO1, ITMY, ITMX. LO1 results were successfully used to diagonalize LO1 input matrix. There are some issues for ITMY, ITMX still. I could not run LO2 test.


The free swing test ran successfully, resonant frequencies for different DOFs was extracted, and new input matrix was calculated. The new matrix was only slightly different from before and it worked fine with existing damping loops. The observed resonance frequencies were different from previous values by POS: -6 mHz, PIT : -3 mHz, YAW: -9 mHz, SIDE: -2 mHz. Attached are the diagonalization result.


The peculiarity of ITMX remained even after the second free swing test. The calculated input matrix is very different from existing one with sign flips across PIT and POS rows. I found that our LR osem is always bright in ITMX at the current alignment position. I see that LR osem comes in range when C1:SUS-ITMX_PIT_COMM is raised above 0.5. Maybe we should run this test when we know for sure ITMX is in correct position.


In ITMY on the other hand, I found that SIDE OSEM was completely bright. This happened during the YAW kick to ITMY. We'll need to reduce kick amplitudes for ITMY and redo this test.


For LO2, I could not initiate the test. On reducing the alignment offsets for LO2 (so that it doesn't get stuck in the fre swing test), the damping loops were not working. This is a clear evidence also that input matrix is different for different positions of the optic. We need to think about some other strategy to do this test, maybe see if ideal input amtrix works at no offsets and use that to damp during the test.

  16938   Wed Jun 22 14:44:03 2022 AnchalUpdateBHDFixed DC error in c1su2, added new library model for suspensions

The 0x2000 error in c1su2 happens whenever we make it and install it as the default data acquisition rates are too much in the suspension model. Earlier we used activateSUS2DQ.py to fix this. I followed the suggestion in 40m/16537 to include COIL_OUT at 16k, damping channels at 256 Hz and OL channels at 1024 Hz. I created new suspension model at /cvs/cds/rtcds/userapps/trunk/sus/c1/models/lib/sus_single_control_new.mdl. The model also contains filter modules names C1SUS_OPT_BIASPOS, C1SUS_OPT_BIASPIT, C1SUS_OPT_BIASYAW which acts on the alignment offsets so that a low pass filter can be added there and alignment offsets always happen slowly. The new suspension model is now used inc1su2 for teh 7 new suspensions, and now the model starts without errors.

Still remaining to fix: IPC communication between c1hpc and c1lsc.

  16946   Sat Jun 25 14:29:48 2022 AnchalUpdateIOOWFS issues

This issue is very weird and still unresolved. Without WFS loops, we'll have to realign IMC often and we might loose IMC alignment completely during weekends or long weekends.

I tried following things today but nothign worked:

  • Blocked WFS PDs and reset DC offsets (sitemap>C1IOO>C1IOO_WFS_MASTER>! Actions>Correct WFS DC Offsets).
  • Switched off MC chamber lights.
    I felt that they might be on, but later I feel that wasn't the case. Anyways, this didn't help.
  • Algined IMC manually using cavAlign tool with MC2-MC3 and then tweaking MC1 and MC3 a little bit. Reach 13.6k in C1:IOO-MC_TRANS_SUM. Then I unlocked IMC with autolocker off, centered beam on WFSs (they were pretty off even though we have been centering them this week), and then reset RF offsets (sitemap>C1IOO>C1IOO_WFS_MASTER>! Actions>Correct WFS DC Offsets). This did not help either.
  • The fact that IMC started misbehaving since Thursday onwards was bugging me that maybe the FE models did not come online properly, that maybe some RTS link is broken in IOO model which is causing the feedback loop to not work. So I went ahead and restarted all models, that didn't help either.
    • Now we have a restartAllModels.sh script which restarts all cds system and restores state to just before restarting. It also makes sure that watchdogs are engaged safely particularly for new suspesnions where alignment offsets are ramped.

We need to investigate this as first priority. Maybe some cable is loose, some PD power supply not working etc. Until we fix this, people should align IMC to > 12000 transmission counts whenever they have a spare 5 min. We need to work in place of WFS for sometime.

  16957   Tue Jun 28 17:07:47 2022 AnchalUpdateCalibrationAdded Beatnote channels in demodulation of c1cal

I added today demodulation of C1:LSC-BEATX/Y_FINE_I/Q in the c1cal demodulation where different degrees of freedom can be dithered. For McCal (formerly soCal), we'll dither the arm cavity for which we can use any of the DOFs (like DARM) to send the dither to ETMX/ETMY. Then with green laser locked as well, we'll get the calibration signal from the beatnotes in the demodulaed channels. We can also read right after the mixing in c1cal model and try differnt poles for integration .

I've also added medm screens in the sensing matrix part of LSC screen. These let you see demodulation of beatnote frequency signals.

  17010   Mon Jul 18 04:42:54 2022 AnchalUpdateCalibrationError propagation to astrophysical parameters from detector calibration uncertainty

We can calculate how much detector calibration uncertainty affects the estimation of astrophysical parameters using the following method:

Let \overrightarrow{\Theta} be set of astrophysical parameters (like component masses, distance etc), \overrightarrow{\Lambda}be set of detector parameters (like detector pole, gain or simply transfer function vaue for each frequency bin). If true GW waveform is given by h(f; \overrightarrow{\Theta}), and the detector transfer function is given by \mathcal{R}(f; \overrightarrow{\Lambda}), then the detected gravitational waveform becomes:
g(f; \Theta, \Lambda) = \frac{\mathcal{R}(f; \overrightarrow{\Lambda_t})}{\mathcal{R}(f; \overrightarrow{\Lambda})} h(f; \overrightarrow{\Theta})

One can calculate a derivative of waveform with respect to the different parameters and calculate Fisher matrix as (see correction in 40m/17017):

\Gamma_{ij} = \left( \frac{\partial g}{\partial \mu_i} | \frac{\partial g}{\partial \mu_j}\right )

where the bracket denotes iner product defined as:

\left( k_1 | k_2 \right) = 4 Re \left( \int df \frac{k_1(f)^* k_2(f))}{S_{det}(f)}\right)

where S_{det}(f) is strain noise PSD of the detector.

With the gamma matrix in hand, the error propagation from detector parameter fractional errors \frac{\Delta \Lambda_j}{\Lambda_j}to astrophysical paramter fractional errors \frac{\Delta \Theta_i}{\Theta_i}is given by (eq 26 in Evan et al 2019 Class. Quantum Grav. 36 205006):

\frac{\Delta \Theta_j}{\Theta_j} = - \mathbf{H}^{-1} \mathbf{M} \frac{\Delta \Lambda_j}{\Lambda_j}

where \mathbf{H}_{ij} = \left( \frac{\partial g}{\partial \Theta_i} | \frac{\partial g}{\partial \Theta_j}\right ) and \mathbf{M}_{ij} = \left( \frac{\partial g}{\partial \Lambda_i} | \frac{\partial g}{\partial \Theta_j}\right ).

Using the above mentioned formalism, I looked into two ways of calculating error propagation from detector calibration error to astrophysical paramter estimations:

Using detector response function model:

If we assume detector response function as a simple DC gain (4.2 W/nm) and one pole (500 Hz) transfer function, we can plot conversion of pole frequency error into astrophysical parameter errors. I took two cases:

  • Binary Neutron Star merger with star masses of 1.3 and 1.35 solar masses at 100 Mpc distance with a \tilde{\Lambda} of 500. (Attachment 1)
  • Binary black hole merger with black masses of 35 and 30 at 400 MPc distance with spin along z direction of 0.5 and 0.8. (I do not fully understand the meaning of these spin components but a pycbc waveform generation model still lets me calculate the effect of detector errors) (Attachment 2)

The plots are plotted in both loglog and linear plots to show the order of magnitude effect and how the error propsagation slope is different for different parameters. 'm still not sure which way is the best to convey the information. The way to read this plot is for a given error say 4% in pole frequency determination, what is the expected error in component masses, merger distance etc. I

Note that the overall gain of detector response is not sensitive to astrophysical error estimation.

Using detector transfer function as frequency bin wise multi-parameter function

Alternatively, we can choose to not fit any model to the detector transfer function and simply use the errors in magnitude and phase at each frequency point as an independent parameter in the above formalism. This then lets us see what is the error propagation slope for each frequency point. The hope is to identify which parts of the calibration function are more important to calibrate with low uncertainty to have the least effect on astrophysical parameter estimation. Attachment 3 and 4 show these plots for BNS and BBH cases mentioned above. The top panel is the error propagation slope at each frequency due to error in magnitude of the detector transfer function at that frequency and the bottom panel is the error propagation slope at each frequency due to error in phase of the detector transfer function.

The calibration error in magnitude and phase as a function of frequency would be multiplied by the curves and summed together, to get total uncertainty in each parameter estimation.

This is my first attempt at this problem, so I expect to have made some mistakes. Please let me know if you can point out any. Like, do the order of magnitude and shape of error propagation makes sense? Also, comments/suggestions on the inference of these plots would be helpful.

Finally, I haven't yet tried seeing how these curves change for different true values of the merger event parameters. I'm not yet sure what is the best way to extract some general information for a variety of merger parameters.

Future goals are to utilize this information in informing system identification method i.e. multicolor calibration scheme parameters like calibration line frequencies and strength.

Code location

  17016   Mon Jul 18 21:41:42 2022 AnchalSummaryLSCFPMI locking procedure using REFL55 and AS55

Now that you have found a working configuration, I suggest we update CARM and DARM filter banks so that they are used in locking those degrees of freedom instead of repurposing XARM/YARM banks. It would be bit easier to understand and leaves room for future changes for one configuration while keeping single arm lock configurations untouched.

  17017   Tue Jul 19 07:34:46 2022 AnchalUpdateCalibrationError propagation to astrophysical parameters from detector calibration uncertainty

Addressing the comments as numbered:

  1. Yeah, that's correct, that equation normally \Delta \Theta = -\mathbf{H}^{-1} \mathbf{M} \Delta \Lambda but it is different if I define \Gamma bit differently that I did in the code, correct my definition of \Gamma to :
    \Gamma_{ij} = \mu_i \mu_j \left( \frac{\partial g}{\partial \mu_i} | \frac{\partial g}{\partial \mu_j} \right )
    then the relation between fractional errors of detector parameter and astrophysical parameters is:
    \frac{\Delta \Theta}{\Theta} = - \mathbf{H}^{-1} \mathbf{M} \frac{\Delta \Lambda}{\Lambda}
    I prefer this as the relation between fractional errors is a dimensionless way to see it.
  2. Thanks for pointing this out. I didn't see these parameters used anywhere in the examples (in fact there is no t_c in documentation even though it works). Using these did not affect the shape of error propagation slope function vs frequency but reduced the slope for chirped Mass M_c by a couple of order of magnitudes.
    1. I used the get_t_merger(f_gw, M1, M2) function from Hang's work to calculate t_c by assuming f_{gw} must be the lowest frequency that comes within the detection band during inspiral. This function is:
      t_c = \frac{5}{256 \pi^{8/3}} \left(\frac{c^3}{G M_c}\right)^{5/3} f_{gw}^{-8/3}
      For my calculations, I've taken f_{gw} as 20 Hz.
    2. I used the get_f_gw_2(f_gw_1, M1, M2, t) function from Hang's work to calculate the evolution of the frequency of the IMR defined as:
      f_{gw}(t) = \left( f_{gw0}^{-8/3} - \frac{768}{15} \pi^{8/3} \left(\frac{G M_c}{c^3}\right)^{5/3} t \right)^{-3/8}
      where f_{gw0} is the frequency at t=0. I integrated this frequency evolution for t_c time to get the coalescence phase phi_c as:
      \phi_c = \int^{t_c}_0 2 \pi f_{gw}(t) dt
  3. In Fig 1, which representation makes more sense, loglog of linear axis plot? Regarding the affect of uncertainties on Tidal amplitude below 500 Hz, I agree that I was also expecting more contribution from higher frequencies. I did find one bug in my code that I corrected but it did not affect this point. Maybe the SNR of chosen BNS parameters (which is ~28) is too low for tidal information to come reliably anyways and the curve is just an inverse of the strain noise PSD, that is all the information is dumped below statistical noise. Maybe someone else can also take a look at get_fisher2() function that I wrote to do this calculation.
  4. Now, I have made BBH parameters such that the spin of the two black holes would be assumed the same along z. You were right, the gamma matrix was degenerate before. To your second point, I think the curve also shows that above ~200 Hz, there is not much contribution to the uncertainty of any parameter, and it rolls-off very steeply. I've reduced the yspan of the plot to see the details of the curve in the relevant region.

1. In the error propogation equation, it should be \Delta \Theta = -H^{-1} M \Delta \Lambda, instead of the fractional error. 

2. For the astro parameters, in general you would need t_c for the time of coalescence and \phi_c for the phase. See, e.g., https://ui.adsabs.harvard.edu/abs/1994PhRvD..49.2658C/abstract.

3. Fig. 1 looks very nice to me, yet I don't understand Fig. 3... Why would phase or amplitude uncertainties at 30 Hz affect the tidal deformability? The tide should be visible only > 500 Hz.

4. For BBH, we don't measure individual spin well but only their mass-weighted sum, \chi_eff = (m_1*a_1 + m_2*a_2)/(m_1 + m_2). If you treat S1z and S2z as free parameters, your matrix is likely degenerate. Might want to double-check. Also, for a BBH, you don't need to extend the signal much higher than \omega ~ 0.4/M_tot ~ 10^4 Hz * (Ms/M_tot). So if the total mass is ~ 100 Ms, then the highest frequency should be ~ 100 Hz. Above this number there is no signal.


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