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ID Date Author Type Category Subject
16512   Thu Dec 16 12:21:16 2021 AnchalUpdateBHDCoil driver test failed for S2100619-v1

Today I found one of the coil driver boards, S2100619 failed the test on CH2. There appears to be an extra phase lag after 10 kHz and some resonant-like feature at 7 kHz. This of course is very high-frequency stuff and maybe we don't care about these deviations. But it could mean something is off with the channel and could potentially lead to failure in the relevant frequency band in the future. I'll need help to debug this. Please see the attachment for details of test failure.

Attachment 1: D1100687_S2100619-v1_TF_CH2_Not_Matching.pdf
16514   Thu Dec 16 15:32:59 2021 AnchalUpdateBHDFinished Coil driver (odd serial number) units tests

We have completed modifications and testing of the HAM Coil driver D1100687 units with serial numbers listed below. The DCC tree reflects these changes and tests (Run/Acq modes transfer functions).

 SERIAL # TEST result S2100609 PASS S2100611 PASS S2100613 PASS S2100615 PASS S2100617 PASS S2100619 FAIL (CH2 phase) S2100621 PASS S2100623 PASS S2100625 PASS S2100627 PASS S2100629 PASS S2100631 PASS S2100633 Waiting for more components S2101649** PASS S2101651** PASS S2101653** PASS S2101655** PASS

** A fix had to be done on the DC power supply for these. The units' regulated power boards were not connected to the raw DC power, so the cabling had to be modified accordingly.

Further, Paco fixed the two even serial number units (S2101648, S211650) that failed the test. The issues were minor soldering mistakes that were easily resolved.

16517   Thu Dec 16 17:57:17 2021 AnchalUpdateBHDFinished Coil driver (odd serial number) units tests

S2100619 was fixed by Koji and it passed the test after that.

Quote:
 SERIAL # S2100619 FAIL (CH2 phase)

The I/O chassis reassigns the ADC and DAC indices on every power cycle. When we moved it, it must have changed it from the order we had. We were aware of this fact and decided to reconnect the I/O chassis to AA/AI to relect the correct order. We forgot to do that but this is not an error, it is expected behavior and can be solved easily.

16527   Mon Dec 20 14:10:56 2021 AnchalUpdateBHDAll coil drivers ready to be used, modified and tested

Koji found some 68nF caps from Downs and I finished modifying the last remaining coil driver box and tested it.

SERIAL # TEST result
S2100633 PASS

With this, all coil drivers have been modified and tested and are ready to be used. This DCC tree has links to all the coil driver pages which have documentation of modifications and test data.

16530   Tue Dec 21 16:52:39 2021 AnchalSummaryElectronicsIn-air Sat Amp to Vacuum Flange cables laid for 7 new SOS

[Anchal, Yehonathan, Chub]

We today laid down 14 70 ft long DB25 cables from 1Y1 (6), 1Y0 (8) to ITMY Chamber (4), BS Chamber (6) and ITMX Chamber (4). The cables have been connected to respective satellite amplifier on the racks and the other ends are connected to the vacuum flange feedthru on ITMX for LO1 and PR2, while the others have been kept near the planned flange postions. LO1 is now ready to be connected to CDS by connecting the in-vacuum cable inside ITMX chamber to the OSEMs.

16533   Wed Dec 22 17:40:22 2021 AnchalSummaryCDSc1su2 model updated with SUS damping blocks for 7 SOSs

[Anchal, Koji]

I've updated the c1su2 model today with model suspension blocks for the 7 new SOSs (LO1, LO2, AS1, AS4, SR2, PR2 and PR3). The model is running properly now but we had some difficulty in getting it to run.

Initially, we were getting 0x2000 error on the c1su2 model CDS screen. The issue probably was high data transmission required for all the 7 SOSs in this model. Koji dug up a script /opt/rtcds/caltech/c1/userapps/trunk/cds/c1/scripts/activateDQ.py that has been used historically for updating the data rate on some of theDQ channels in the suspension block. However, this script was not working properly for Koji, so he create a new script at /opt/rtcds/caltech/c1/chans/daq/activateSUS2DQ.py.

[Ed by KA: I could not make this modified script run so that I replaces the input file (i.e. C1SU2.ini). So the output file is named C1SU2.ini.NEW and need to manually replace the original file.]

With this, Koji was able to reduce acquisition rate of SUSPOS_IN1_DQ, SUSPIT_IN1_DQ, SUSYAW_IN1_DQ, SUSSIDE_IN1_DQ, SENSOR_UL, SENSOR_UR, SENSOR_LL,SENSOR_LR, SENSOR_SIDE, OPLEV_PERROR, OPLEV_YERROR, and OPLEV_SUM to 2048 Sa/s. The script modifies the /opt/rtcds/caltech/c1/chans/daq/C1SU2.ini file which would get re-written if c1su2 model is remade and reinstalled. After this modification, the 0x2000 error stopped appearing and the model is running fine.

### Should we change the library model part for sus_single_control.mdl

We notice that all our suspension models need to go through this weird python script modifying auto-generated .ini files to reduce the data rate. Ideally, there is a simpler solution to this by simply adding the datarate 2048 in the '#DAQ Channels' block in the model library part /cvs/cds/rtcds/userapps/trunk/sus/c1/models/lib/sus_single_control.mdl which is the root model in all the suspensions. With this change, the .ini files will automatically be written with correct datarate and there will be no need for using the activateDQ script. But we couldn't find why this simple solution was not implemented in the past, so we want to know if there is more stuff going on here then we know. Changing the library model would obviously change every suspension model and we don't want a broken CDS system on our head at the begining of holidays, so we'll leave this delicate task for the near future.

16541   Tue Jan 4 18:26:59 2022 AnchalUpdateBHDTested 2" PR2 candidates transmission

I used the rejected light from the PBS after the motorized half-wave plate between PMC and IMC injection path (used for input power control to IMC) to measure the transmission of PR2 candidates. These candidates were picked from QIL (QIL/2696). Unfortunately, I don't think either of these mirrors can be used for PR2.

 Polarization Incident Power [mW] Transmitted Power [mW] Transmission [ppm] V2-2239 & V2-2242 s-pol 940 0.015 16.0 V2-2239 & V2-2242 p-pol 935 0.015 16.0 V6-704 & V6-705 p-pol 925 21 22703

If I remember correctly, we are looking for a 2" flat mirror with a transmission of the order of 1000 ppm. The current PR2 is supposed to have less than 100 ppm transmission which would not leave enough light for LO path.

I've kept the transmission testing setup intact on the PSL table, I'll test existing PR2 and another optic (which is 0.5" thick unfortunately) tomorrow.

16543   Wed Jan 5 17:46:04 2022 AnchalUpdateBHDTested 2" PR2 candidates transmission

I tested 2 more optics today, the old PR2 that we took out and another optic I found in QIL. Both these optics are also not good for our purpose.

 Polarization Incident Power [mW] Transmitted Power [mW] Transmission [ppm] Existing PR2 p-pol 910 0.004 4.4 V2-1698 & V2-1700 p-pol 910 595 653846

I'll find thw Y1S optic and test that too. We should start looking for alternate solutions as well.

16545   Thu Jan 6 11:54:20 2022 AnchalSummaryBHDPart IX of BHR upgrade - Placed AS1 and AS4

[Paco (Vacuum Work), Anchal]

Today we opened the ITMY Chamber and installed suspended AS1 and AS4 in their planned positions. In doing so, we removed the razor or plate mounted on a pico motor at the south end of the table (see 40m/16450). We needed to make way for AS4 to be installed.

We need more dog clamps for installing the suspensions, we have used temporary clamps for now. However, knows where new C&B clamps are, please let us know.

16546   Thu Jan 6 12:52:49 2022 AnchalUpdateCDSYearly DAQD fix 2022!

Just as predicted, all realtime models reported "0x4000" error. Read the parent post for more details. I fixed this by following the instructions. I add folowing lines to the file /opt/rtcds/rtscore/release/src/include/drv/spectracomGPS.c in fb1:

/* 2020 had 366 days and no leap second */
pHardware->gpsOffset += 31622400;
/* 2021 had no leap seconds or leap days, so adjust for that */
pHardware->gpsOffset += 31536000;

Then is made the package and reloaded it after stoping the daqd services. This brought back all the fast models except C1SUS2 models which are in red due to some other reason that I'll investigate further.

16552   Thu Jan 6 21:04:41 2022 AnchalSummaryBHDPart VIII of BHR upgrade - LO1 OSEMs inserted

[Anchal, Koji] Part of elog: 40m/16549.

The magnets on the mirror face are arranged in a manner that the overall magnetic dipole moment is nullified faraway. Because of this, the coil output gains in all such optics need to have positive and negative signs in a butterfly mode pattern (eg. UL, LR: +ve and UR, LL: -ve).

In the particular case of LO1, we chose following coil output gains:

COIL_GAIN
UL -1
UR 1
LR -1
LL 1
SD -1

This ensures that all damping gains have positive signs. Following damping gain values were chosen:

DOF C1:SUS-LO1_SUSXXX_GAIN
POS 5
PIT 2
YAW 0.2
SIDE 10

Having said that, this is a convention and we need to discuss more on what we want to set a convention (or follow a previous one if it exists). My discussion with Koji came up with the idea of fixing the motion response of an OSEM with respect to coil offset by balancing the coil gains across all optics and use same servo gains for all optics afterwards. But it is a complicated thought coming out of tired minds, needs more discussion.

### Important notes for suspending the optics:

• Do not insert the OSEMs fully. Leave all of the magnet out of the OSEMs before transportation.
• Tighten the OSEMs completely while adjusting the height of the optic. Adjust height of OSEM holder plate if necessary.
• Ensure the all cage screws are screwed tight completely.

16554   Fri Jan 7 16:17:42 2022 AnchalSummaryBHDPart IX of BHR upgrade - Placed AS1 and AS4 filters

[paco]

Added input filters, input matrix, damping filters, output matrix, coil filters, and copy the state over from LO1 into AS1 screen in anticipation for damping.

Added input filters, input matrix, damping filters, output matrix, coil filters, and copy the state over from LO1 into AS4 screen in anticipation for damping.

16555   Fri Jan 7 17:54:13 2022 AnchalUpdateBHDPR2 Sat Amp has a bad channel

[Anchal, Paco]

Yesterday we noticed that one of the ADC channels was overflowing. I checked the signal chain and found that CH3 on PR2 Sat Amp was railing. After a lot of debugging, our conclusion is that possible the PD current input trace is shorted to the positive supply through a finite resistance on the PCB. This would mean this PCB has a manufacturing defect. The reason we come to this conclusion is that even after removing the opamp U3 (AD822ARZ), we still measure 12.5 V at the pins of R25 (100 Ohm input resistance)

Please see the schematic for reference. We also checked the resistance between input of R25 (marked PDA above) and positive voltage rail and it came out as 3 kOhms. While I all other channels, this value was 150 kOhms.

I would like it if someone else also takes a look at this. We probably would need to change the PCB in this chassis or use a spare chassis.

16560   Mon Jan 10 13:35:52 2022 AnchalUpdateBHDPR2 Sat Amp has a bad channel

The unit was tested before by Tege. The test included testing the testpoint voltages only. He summarized his work in this doc. The board number is S2100737. Here are the two comments about it:
"This unit presented with an issue on the PD1 circuit of channel 1-4 PCB where the voltage reading on TP6, TP7 and TP8 are -15.1V,  -14.2V, and +14.7V respectively, instead of ~0V.  The unit also has an issue on the PD2 circuit of channel 1-4 PCB because the voltage reading on TP7 and TP8 are  -14.2V, and +14.25V respectively, instead of ~0V."

"Debugging showed that the opamp, AD822ARZ, for PD2 circuit was not working as expected so we replaced with a spare and this fixed the problem. Somehow, the PD1 circuit no longer presents any issues, so everything is now fine with the unit."

Note:  No issues were reported on PD3 circuit is is malfunctioning now.

 Quote: Also: Was this unit tested before? If so, what was the testing result at the time?

16562   Mon Jan 10 14:52:51 2022 AnchalSummaryBHDLO1 OSEMs roughly calibrated and noise measured

I used the open light level output of 908 for ITMX side OSEM from 40m/16549 to roughly calibrate cts2um filter module in LO1 OSEM input filters. All values were close to 0.033. As the calibration reduces the signal value by about 30 times, I increased all damping gains by a factor of 30. None of loops went into any unstable oscillations and I witnessed damping of kicks to the optic.

### In-loop power spectrum

I also compared in-loop power spectrum of ETMX and LO1 while damping. ETMX was chosen because it is one of the unaffected optics by the upgrade work. ITMX is held by earthquake stops to avoid unnecessary hits to it while doing chamber work.

Attachment 1 and 2 show the power spectrum of in-loop OSEM values (calibrated in um). At high frequencies, we see about 6 times less noise in LO1 OSEM channel noise floor in comparison to ETMX. Some peaks at 660 Hz and 880 Hz are also missing. At low frequencies, the performance of LO1 is mostly similar to EMTX except for a peak (might be loop instability oscillation) at 1.9 Hz and another one at 5.6 Hz. I'll not get into noise hunting or loop optimization at this stage for the suspension. For now, I believe the new electronics are damping the suspensions as good as the old electronics.

Attachment 1: LO1_vs_ETMX_OSEM_Spectrum_LF_x30_Gain.pdf
Attachment 2: LO1_vs_ETMX_OSEM_Spectrum_HF_x30_Gain.pdf
16565   Mon Jan 10 17:04:47 2022 AnchalUpdateBHDAS1 Sat Amp CH2 had offset

We found that there was a small offset (~300 mV) at TP6 and TP8, in PD2 circuit (CH2 of the board). I replaced U3 AD822ARZ but did not see any affect. I disconnected the adaptor board in the back and saw that the offset went away. This might mean that the cable had some flaky short to a power supply pin. However, when I just reinserted the adaptor board back again, there was no offset. We could not find any issue with the board after that to fix, so we left it as it is. If this board gives offset issues in the future, most probably the ribbon cable would be the suspect.

Now all ADC channels are showing no offset or overflows in C1SU2 chassis.

16566   Mon Jan 10 18:20:45 2022 AnchalUpdateBHDTested 2" PR2 candidates transmission

I tested 2 more optics found by Paco and Yehonathan in QIL.

Polarization Incident Power [mW] Transmitted Power [mW] Transmission [ppm]
V6-704 V6-706 p-pol 850 17.1 20118
Yellow cylindrical box p-pol 850 <1 ( could not even see it to measure it with a more sensitive power meter) <1000

I would like someone to redo the second test. I'm not sure what was happening but I could not find the transmitted beam at all on my card even with all lights out. This is either too good a coating and not useful for us or I did something wrong while measuring it.

V6-704, V6-706 mirror seemed like a good candidate as the paper with it said it would be a 200 ppm mirror. But I measured a lot more transmission than that. Now that I see that paper more carefully, it is a 45 degree s-pol mirror, probably that's why it had so much transmission for p-pol at near-normal incidence.

16567   Mon Jan 10 18:36:41 2022 AnchalSummaryBHDLO1 free swinging test set to trigger

LO1 is set to go through a free swinging test at 1 am tonight. We have used this script (scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on rossa, type:

tmux a -t freeSwingLO1

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

16572   Tue Jan 11 12:19:12 2022 AnchalSummaryBHDLO1 Input Matrix Diagonalization performed.

The frree swinging test was successful. I ran the input matrix diagonalization code (scripts/SUS/InMAtCalc/sus_diagonalization.py) on the LO1 free swinging data collected last night. The logfile and results are stroed in scripts/SUS/InMatCalc/LO1 directory. Attachment 1 shows the power spectral density of the DOF bassis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

Free Swinging Resonances Peak Fits
Resonant Frequency [Hz] Q A
POS 0.941 506 84
PIT 1.015 304 778
YAW 0.694 300 626
SIDE 0.999 371 49

LO1 New Input Matrix
UL UR LR LL SIDE
POS
0.12
0.137
0.338
0.321
0.004
PIT
1.282
1.087
-0.57
-0.375
-0.843
YAW
1.07
-0.921
-1.081
0.91
0.098
SIDE
-0.042
0.383
0.326
-0.099
0.857

The new matrix was loaded on LO1 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

Attachment 1: LO1_SUS_InpMat_Diagnolization.pdf
Attachment 2: LO1_FreeSwingData_PeakFitting.pdf
16575   Tue Jan 11 15:21:16 2022 AnchalUpdateBHDPR2 transmission calculation

I did this simple calculation where I assumed 1W power from laser and 10% transmission past IMC. We would go ahead with V6-704/V6-705 ATFilms 3/8" optic. It would bring down the PRC gain to ~30 but will provide plenty of light for LO beam and alignment.

Attachment 1: LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PRS_Trans_Calc.ipynb.zip
16577   Tue Jan 11 18:18:29 2022 AnchalSummaryBHDAttempted OSEM installation on AS1

[Anchal, Paco, Yehonathan]

Connected in-cir cable to new flange on ITMY Chamber

Connected OSEM one-by-one. Starting from top right  to left (PIn1)

1st connector: LL -> UR -> UL

2nd connector: LR -> SD

Loosening all OSEMs and taking them out and noting full bright readings:

• SD: 29564 -> 14787
• LR: 30902 -> 15451
• UR: 29280 -> 14640
• LL: 27690 -> 13845
• UL: 27668 -> 13834

:( We had to stop here as we were unable to actuate on the side coils. We checked the signal chain and found that the monitor output of AS1 LL/SD coil driver is responding to offset changes in the coil output filter module of AS1 side. However, when we connected the output of the coil driver through a breakout board to the AS1 Sat Amp, we saw no signal. We tried switching the coil driver bo with another one one the rack but we found the exact same issue. This led us to believe that something must be wrong with the AS1 Sat Amp. We checked the output of the AS1 LL/SD coil driver without connecting it to the sat amp and found that the output was responding to our CDS changes. Then we checked the second "Coil Input" port of the AS1 Sat Amp, and found that pins 2-7 and pins 3-8 are shorted. This means channel 5 and 8 on this box would be shorted. This is the reason why we were unable to actuate on the coils. I'll work on debugging this box, my first guess is that the ribbon cable is bad.

16578   Tue Jan 11 18:40:25 2022 AnchalSummaryBHDAS1 Sat Amp has a PCB issue

AS1 Sat Amp (S2100741) has a critical PCB issue on it's Ch5-8 board S2100548. This board is supposed to just feed through the coil driver signal from the front DB9 connector to the back DB25 connector but it has a short between pins 2 and 7 at the "Coil Input" end (connector J1). The short persists even after I disconnect the sat amp to the flange connector on the back of this board, which definitely means the short is present in the passive channeling through the PCB or at the soldering points of the two DB connectors. I just flipped the board and found that the soldering connections are clean and separate. I think we'll have to use one of the spare sat amp boxes for AS1 for now, while we either declare this one manufacture defected or fix the issue.

I actually found the short on the PCB trace by just looking carefully at it. Attachment 1 shows the photo of it. Maybe we can fix this by simply cutting the tumor between the two traces (why are these traces so close together in such a large board anyways!!!), but I'm not sure if that is a reliable way of fixing this issue. I'll wait for Koji's comments on what to do with this. We'll recommence OSEM tuning for AS1 tomorrow with fixed electronics.

Attachment 1: signal-2022-01-11-184917.jpeg
16579   Thu Jan 13 09:48:41 2022 AnchalSummaryBHDAS1 Sat Amp fixed

I fixed the issue in AS1 Sat Amp (S2100741) by using a razor blade. I cut the short between the two places, cleaned up the area and covered it with electrical tape. However, later feedback from Rana was to not use electrical tape as it dries up and becomes brittle and lfaky in long run. So after the AS1 OSEM tuning is over, I'll open this box again and use something else to insulate the exposed area. See attached pictures for current status.

Attachment 1: signal-2022-01-13-094823_001.jpeg
Attachment 2: signal-2022-01-13-094823_002.jpeg
16580   Thu Jan 13 12:24:08 2022 AnchalSummaryBHDAS1 SD and LR magnets broke

[Anchal (vacuum work), Paco (outside)]

After the AS1 Sat Amp fix (40m/16579), we today were able to tune all OSEMs to the mid-bright level. But when we were about to call it, we were told that the new PEEK earthquake stop screw and bolts need to go on the thin suspended optics. Against better judgment, we decided to install the new back earthquake stop in-situ since we had tuned all OSEMs already. I installed the new stop but after that found that in the process I have broken off the side magnet and LR magnet from the optic adaptor and they are inside the OSEM coils now. This means we'll have to redo the AS1 suspension almost from scratch again . We have transported AS1 to the cleanroom where the work on re-suspension has begun.

16581   Thu Jan 13 12:29:27 2022 AnchalSummaryBHDAS4 LR magnet broke

After the debacle with AS1 (40m/16580), we decided the put the PEEK earthquake stop by first removing the lower OSEM plate and then doing it. So I unfastened AS4 from its position with the earthquake stops in place and moved the suspension to the center of the table. Then I carefully removed the bottom OSEM plate. But I found out that the LR magnet is broken and lying on the floor of the suspension . Given my past on the same day, it could be me breaking it again during the moving of the suspension of taking off the OSEM plate or there is a small chance that this break happened before. Regardless of fault, this meant we have to resuspend AS4 again as well. So we transported AS4 back to the clean room and the work on it's re-suspension has begun.

16583   Thu Jan 13 17:10:55 2022 AnchalUpdateBHDPR2 transmission calculation

I corrected the calculation by adding losses by the arm cavity ends times the arm cavity finesse and also taking into account the folding of the cavity mirror. I used exact formula for finesse calculation and divided it by pi to get the PRC gain from there. Attachment 3 is the notebook for referring to the calculations I made.

Note that using V6-704 would provide 35 mW of LO power when PRFPMI is locked and 113 uW for alignment, but will bring down the PRC Gain to 17.5.

pre-2010 ITM (if it is still an option) would provide 12 mW of LO power when PRFPMI is locked and 28 uW for alignment, but will keep the PRC Gain to 24.6.

I still have to do a curvature check on the V6-704 optic.

Attachment 1: LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PR2_Trans_Calc.ipynb.zip
16585   Fri Jan 14 11:00:29 2022 AnchalUpdateBHDPR2 transmission calculation

Yeah, I counted the loss from arm cavities as the transmission from ETMs on each bounce. I assumed Michelson to be perfectly aligned to get no light at the dark port.  Should I use some other number for the round-trip loss in the arm cavity?

16586   Fri Jan 14 12:01:21 2022 AnchalUpdateElectronicsBS & ITMY feedthroughs labeled and connected to Sat Amps

I labeled all the newly installed flanges and connected the in-air cables (40m/16530) to appropriate ports. These cables are connected to the CDS system on 1Y1/1Y0 racks through the satellite amplifiers. So all new optics now can be damped as soon as they are placed. We need to make more DB9 plugs for setting "Acquire" mode on the HAM-A coil drivers since our Binary input system is not ready yet. Right now, we only have 2 such plugs which means only one optic and be damped at a time.

16587   Fri Jan 14 13:46:25 2022 AnchalUpdateBHDPR2 transmission calculation updated

I updated the arm cavity roundtrip losses due to scattering. Yehonathan told me that arm cavity looses 50ppm every roundtrip other than the transmission losses. With the updated arm cavity loss:

PRFPMI LO Power (mW) Unlocked PRC LO Power (uW) PRC Gain
pre-2010 ITM 8 28 15.2
V6:704 24 113 12

Attachment 1: LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PR2_Trans_Calc.ipynb.zip
16590   Fri Jan 14 18:12:47 2022 AnchalSummaryBHDAS4 placed in ITMY Chamber, OSEMs connected

AS4 was succesfully suspended and trasported to ITMY chamber (40m/16589). We placed it near the door to make it easy to tune the OSEMs. We connected the OSEMs and found that the LL OSEM is not responding. Even though the the OSEMs are completely out right now, there was no signal on this OSEM. This could be an issue in either at the LED driver circuit or the PD circuit in AS4 Sat Amp box, or it could be the OSEM that is bad. We'll investigate further next day. For now, we recorded the full brightness reading for the OSEMs:

• UL: 32767  -> 16383
• UR: 29420 -> 14710
• LR: 30100 -> 15050
• SD: 29222 -> 14611

Another thing to note is that UL value above is not changing at all. I checked the CDS screen and the the ADC input is overflowing in complete bright position of the OSEM.

16593   Tue Jan 18 18:16:28 2022 AnchalSummaryBHDPart IV of BHR upgrade - SR2 Sat Amp Box inspection

I tested the monitor ports on the SR2 Sat Amp Box but found that all LED Mon and PD Mon are giving expected values. I disconnected the cable to OSEM and checked the PD monitors and found no offsets in case of no PD current. I realised that PD transimpedance offset should be checked with PD inputs shorted instead. So I created a male DB 25 connector with pinds 2-3, 50-6, 8-9 and 11-12 shorted. This on connecting to the OSEM cable at the back of sat amp boxes should short the PD inputs. On using this plug, I found no offsets in any of the Sat Amp PD output channels.

### Discussion with Koji

It is possible that the issue is there because the magnet is missing the LED-PD path way because it is offset sideways. In fact, in my limited memory, I do not recall seeing the UL OSEM signal ever going to complete darkness either. Tomorrow, we should take a photo of the OSEMs from the back and see if any sideways adjustment of the top OSEM plate is required. If any adjustment is required, we must take the OSEMs out and then do the adjustment. Do not attempt to adjust OSEM plate with OSEMs inserted in-situ. That will most probably knock off the magnets.

16595   Wed Jan 19 12:50:10 2022 AnchalSummaryBHDPart IV of BHR upgrade - SR2 OSEM tuning progress.

It was indeed the issue of the top OSEM plate not being in the right place horizontally. But the issue was more non-trivial. I believe because of the wedge in thick optics, there is a YAW offset in the optic in the free hanging position. I had to readjust the OSEM plate 4 times to be able to get full dark to bright range in both upper OSEMs. After doing that, I tuned the four OSEMs somewhat near the halfway point and once I was sure I'm inside the sensitive region in all face OSEMs, I switched on POS, PIT, and YAW damping. Then I was able to finely tune the positions of both upper OSEMs.

However, on reaching to lower right OSEM, I found again the same issue. I had to stop to go to the 40m meeting, I'll continue this work in the afternoon. But OSEM plate adjustment in the horizontal direction, particularly for thick optics is required to be done before transporting them. I achieved the best position by turning the OSEM 90 degrees and using the OSEM LED/PD plates to determine the position. This was the final successful trial I did in adjusting the plate position horizontally.

16598   Wed Jan 19 16:22:48 2022 AnchalUpdateBHDPR2 transmission calculation updated

I have further updated my calculation. Please find the results in the attached pdf.

Following is the description of calculations done:

### Arm cavity reflection:

Reflection fro arm cavity is calculated as simple FP cavity reflection formula while absorbing all round trip cavity scattering losses (between 50 ppm to 200 ppm) into the ETM transmission loss.

So effective reflection of ETM is calculated as

$r_{\rm ETMeff} = \sqrt{1 - T_{\rm ETM} - L_{\rm RT}}$

$r_{\rm arm} = \frac{-r_{\rm ITM} + r_{\rm ETMeff}e^{2i \omega L/c}}{1 - r_{\rm ITM} r_{\rm ETMeff}e^{2 i \omega L/c}}$

The magnitude and phase of this reflection is plotted in page 1 with respect to different round trip loss and deviation of cavity length from resonance. Note that the arm round trip loss does not affect the sign of the reflection from cavity, at least in the range of values taken here.

### PRC Gain

The Michelson in PRFPMI is assumed to be perfectly aligned so that one end of PRC cavity is taken as the arm cavity reflection calculated above at resonance. The other end of the cavity is calculated as a single mirror of effective transmission that of PRM, 2 times PR2 and 2 times PR3. Then effective reflectivity of PRM is calculated as:

$r_{\rm PRMeff} = \sqrt{1 - T_{\rm PRM} - 2T_{\rm PR2} - 2T_{\rm PR3}}$

$t_{\rm PRM} = \sqrt{T_{\rm PRM}}$

Note, that field transmission of PRM is calculated with original PRM power transmission value, so that the PR2, PR3 transmission losses do not increase field transmission of PRM in our calculations. Then the field gain is calculated inside the PRC using the following:

$g = \frac{t_{\rm PRM}}{1 - r_{\rm PRMeff} r_{\rm arm}e^{2 i \omega L/c}}$

From this, the power recycling cavity gain is calculated as:
$G_{\rm PRC} = |g|^2$

The variation of PRC Gain is showed on page 2 wrt arm cavity round trip losses and PR2 transmission. Note that gain value of 40 is calculated for any PR2 transmission below 1000 ppm. The black verticle lines show the optics whose transmission was measured. If V6-704 is used, PRC Gain would vary between 15 and 10 depending on the arm cavity losses. With pre-2010 ITM, PRC Gain would vary between 30 and 15.

### LO Power

LO power when PRFPMI is locked is calculated by assuming 1 W of input power to IMC. IMC is assumed to let pass 10% of the power ($L_{\rm IMC}=0.1$). This power is then multiplied by PRC Gain and transmitted through the PR2 to calculate the LO power.

$P_{\rm LO, PRFPMI} = P_{\rm in} L_{\rm IMC}G_{\rm PRC}T_{\rm PR2}$

Page 3 shows the result of this calculation. Note for V6-704, LO power would be between 35mW and 15 mW, for pre-2010 ITM, it would be between 15 mW and 5 mW depending on the arm cavity losses.

The power available during alignment is simply given by:
P_{\rm LO, align, PRM} = P_{\rm in} L_{\rm IMC} T_{\rm PRM} T_{\rm PR2}

P_{\rm LO, align, no PRM} = P_{\rm in} L_{\rm IMC} T_{\rm PR2}

If we remove PRM from the input path, we would have sufficient light to work with for both relevant optics.

I have attached the notebook used to do these calculations. Please let me know if you find any mistake in this calculation.

Attachment 1: PR2transmissionSelectionAnalysis.pdf
Attachment 2: PR2_Trans_Calc.ipynb.zip
16605   Thu Jan 20 17:03:36 2022 AnchalSummaryBHDPart IV of BHR upgrade - SR2 OSEM tuned.

The main issue with SR2 OSEMs, now that I think of it, was that the BS table was very inclined due to the multiple things we removed (including counterweights). Today the first I did was level the BS table by placing some counterweights in the correct positions. I placed the level in two directions right next to SR2 (clamped in its planned place), and made the bubble center.

While doing do, at one point, I was trying to reach the far South-West end of the table with the 3x heavy 6" cylindrical counterweight in my hand. The counterweight slipped off my hand and fell from the table. See the photo in attachment 1. It went to the bottommost place and is resting on its curved surface.

This counterweight needs to be removed but one can not reach it from over the table. So to remove it, we'll have to open one of the blank flanges on the South-west end of BS chamber and remove the counterweight from there. We'll ask Chub to help us on this. I'm sorry for the mistake, I'll be more careful with counterweights in the future.

Moving on, I tuned all the SR2 OSEMs. It was fairly simple today since the table was leveled. I closed the chamber with the optic free to move and damped in all degrees of freedom.

SUSPENSION STATUS UPDATED HERE

Attachment 1: DJI_0144.JPG
16608   Thu Jan 20 18:16:29 2022 AnchalUpdateBHDAS4 set to trigger free swing test

AS4 is set to go through a free swinging test at 10 pm tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

tmux a -t AS4

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

16609   Thu Jan 20 18:41:55 2022 AnchalSummaryBHDSR2 set to trigger free swing test

SR2 is set to go through a free swinging test at 3 am tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

tmux a -t SR2

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

16610   Fri Jan 21 11:24:42 2022 AnchalSummaryBHDSR2 Input Matrix Diagonalization performed.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on theSR2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/SR2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

Free Swinging Resonances Peak Fits
Resonant Frequency [Hz] Q A
POS 0.982 340 3584
PIT 0.727 186 1522
YAW 0.798 252 912
SIDE 1.005 134 3365

SR2 New Input Matrix
UL UR LR LL SIDE
POS
1.09

0.914
0.622
0.798
-0.977

PIT
1.249
0.143
-1.465
-0.359
0.378

YAW
0.552

-1.314
-0.605
1.261

0.118
SIDE
0.72
0.403
0.217
0.534

3.871


The new matrix was loaded on SR2 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

Attachment 1: SR2_SUS_InpMat_Diagnolization_20220121.pdf
Attachment 2: SR2_FreeSwingData_PeakFitting_20220121.pdf
16613   Fri Jan 21 16:40:10 2022 AnchalUpdateBHDAS4 Input Matrix Diagonalization performed.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the AS4 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/AS4 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

Free Swinging Resonances Peak Fits
Resonant Frequency [Hz] Q A
POS 1.025 337 3647
PIT 0.792 112 3637
YAW 0.682 227 1228
SIDE 0.993 164 3094

AS4 New Input Matrix
UL UR LR LL SIDE
POS
0.844
0.707
0.115
0.253
-1.646

PIT
0.122
0.262
-1.319
-1.459
0.214

YAW
1.087

-0.901
-0.874
1.114

0.016
SIDE
0.622
0.934
0.357
0.045

3.822


The new matrix was loaded on AS4 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

Attachment 1: AS4_SUS_InpMat_Diagnolization_20220121.pdf
Attachment 2: AS4_FreeSwingData_PeakFitting_20220121.pdf
16618   Mon Jan 24 18:53:09 2022 AnchalSummaryBHDPart VIII of BHR upgrade - LO2 placed and OSEMs tuned

I placed LO2 in its planned position in BS chamber, inserted the OSEMs, and tuned their position to halfway brightness. At the end of the work, I was able to damp the optic successfully. The full open (full brightness) OSEM ADC counts are:

UL 25743.  -> 12876
UR 27384. -> 13692
LL 25550. -> 12775
LR 27395 -> 13697
SD 28947 -> 14473

Today's OSEM tuning was relatively unhappening. I have only following two remarks:

• BS table was 3 SOS near the East end and PRM is parked in the center, thus the table is very unevenly balanced. I had to use all available counter weights to make it flat near the LO2 suspension.
• The side OSEM for LO2 is not exactly centered (probably due to table imbalance). I was able to balance the table to a point though that the side OSEM was responsive to full range and I was able to damp the optic.

### Free swinging test set to trigger

LO2 is set to go through a free swinging test at 10 pm tonight. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

tmux a -t LO2

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

SUSPENSION STATUS UPDATED HERE

16619   Mon Jan 24 20:48:48 2022 AnchalUpdateBHDAS4 Input Matrix Diagonalization performed.

I agree. That's an interesting idea. But does that mean that there is an always working inverse matrix solution or that any solution will be vulnerable to the alignment biases.

I think we can also calculate the matrix rotation required as a function of dc biases and do that rotation in the simulimk model.

 Quote: I think our suspension input matrix diagonalization is not so robust usually because we only choose a inverting matrix which gives the best separation for a single suspension alignment. i.e. we have seen in the past that adjusting the bias for the alignment makes the matrix inversion not work well. Sometime people turn OFF the alignment bias before making the ringdown and that makes the whole measurement invalid. This is because the sensitivity of the OSEMs to longitudinal and/or transverse motion is significantly different for different alignment. I wonder if there's a way we can choose a better matrix by putting in random gain errors on the shadow sensor signals and then finding the matrix which gives the best diag under an ensemble of gain errors.

16621   Tue Jan 25 10:55:02 2022 AnchalSummaryBHDPart VIII of BHR upgrade - LO2 input matrix diagonalization performed.

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the LO2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/LO2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks.

Free Swinging Resonances Peak Fits
Resonant Frequency [Hz] Q A
POS 0.981 297 3967
PIT 0.677 202 1465
YAW 0.775 2434 1057
SIDE 1.001 244 4304

LO2 New Input Matrix
UL UR LR LL SIDE
POS
0.46
1.237
1.094
0.318
0.98
PIT
1.091
0.252
-1.512
-0.672
-0.088
YAW
0.722
-1.014
-0.217
1.519
0.314
SIDE
-0.747
1.523
1.737
-0.534
3.134

The new matrix was loaded on LO2 input matrix and this resulted in no control loop oscillations at least. I'll compare the performance of the loops in future soon.

16622   Tue Jan 25 11:02:54 2022 AnchalSummaryBHDPart IX of BHR upgrade - AS1 free swing test failed

For some reasonf the free swing test showed only one resonance peak (see attachment 1). This probably happened because one of the earthquake stops is touching the optic. Maybe after the table balancing, the table moved a little over its long relazation time and by the time the free swing test was performed at 3 am, one of the earthquake stops was touching the optic. We need to check this when we open the chamber next.

Attachment 1: AS1_freeSwingTestFailed.pdf
16623   Tue Jan 25 16:42:03 2022 AnchalSummaryBHDReduced filter gains in all damped new SOS

I noticed that our current suspension damping loops for the new SOS were railing the DAC outputs. The reason being that cts2um module has not been updated for most optics and thus teh OSEM signal (with the new Sat Amps) is about 30 times stronger. That means our usual intuition of damping gains is too high without applying correct conversion cts2um filter module. I reduced all these gains today and nothing is overflowing the c1su2 chassis now. I also added two options in the "!" (command running drop down menu) in the sus_single medm screens for opening ndscope for monitoring coil outputs or OSEM inputs of the optic whose sus screen is used.

16627   Thu Jan 27 17:57:35 2022 AnchalSummaryBHDPart III of BHR upgrade - Replaced small suspended PR3 with new SOS PR3 and OSEM tuning

[Anchal, Paco]

We removed the old PR3 housed in a tip-tilt style suspension and put it on the North flow bench in the cleanroom. I put PR3 in an accessible position near the North West edge of the BS chamber and balanced the table again with many weights. The OSEM tuning was very uneventful and easy. Following are the full brightness ADC counts for the OSEMs:
UL 25693. -> 12846
UR 24905. -> 12452
LL 23298. -> 11649
LR 24991. -> 12495
SD 26357. -> 13178

I was able to damp the optic easily after the OSEM installation with no issues.

16632   Fri Jan 28 16:35:18 2022 AnchalSummaryBHDAS1, PR2 and PR3 set to trigger free swing test

AS1, PR2 and PR3 are set to o go through a free swinging test at 3 am. We have used this script (Git/40m/scripts/SUS/InMatCalc/freeSwing.py) reliably in the past so we expect no issues, it has a error catching block to restore all changes at the end of the test or if something goes wrong.

To access the test, on allegra, type:

tmux a -t AS1
tmux a -t PR2
tmux a -t PR3

Then you can kill the script if required by Ctrl-C, it will restore all changes while exiting.

16637   Wed Feb 2 16:22:00 2022 AnchalSummaryBHDPart III of BHR upgrade - PR2 inpute matrix diagonalized

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR2 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR2 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.

Attachment 1: PR2_FreeSwingData_PeakFitting_20220125.pdf
Attachment 2: PR2_SUS_InpMat_Diagnolization_20220202.pdf
16638   Wed Feb 2 16:27:57 2022 AnchalSummaryBHDPart III of BHR upgrade - PR3 inpute matrix diagonalized

The free swinging test was successful. I ran the input matrix diagonalization code (/opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/sus_diagonalization.py) on the PR3 free-swinging data collected last night. The logfile and results are stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMAtCalc/PR3 directory. Attachment 1 shows the power spectral density of the DOF basis data (POS, PIT, YAW, SIDE) before and after the diagonalization. Attachment 2 shows the fitted peaks. I chose to not type out the matrix values now. One can find them in teh repo links above.

Attachment 1: PR3_FreeSwingData_PeakFitting_20220125.pdf
Attachment 2: PR3_SUS_InpMat_Diagnolization_20220202.pdf
16639   Wed Feb 2 16:32:02 2022 AnchalSummaryBHDPart IX of BHR upgrade - AS1 free swing test still not good

We still did not get a good AS1 free swinging spectrum. It seems the Side OSEM is reporting coupling to too many DOFs and some extra resonances than we expect. So we did not upload the new input matrix calculated from this test. I'm attaching teh peak fitting (attachment 1) and the diagonalization attempt (attachment 2) to give some idea of what happened. Note how different this fre swinging spectrum looks from the other optics. Given that Yehonathan also felt that somthing might be off with this optic, we need to reevaluate if the suspension has wire not aligned in grove, or it is imbalanced or something else if touching it still.

Attachment 1: AS1_FreeSwingData_PeakFitting_20220125.pdf
Attachment 2: AS1_SUS_InpMat_Diagnolization_20220202.pdf
16647   Fri Feb 4 10:21:39 2022 AnchalSummaryGeneralComplete lab shutdown

Please edit this same entry throughout the day for the shutdown elogging.

I took a screenshot of C0VAC_MONITOR.adl to ensure that all pnematic valves are in closed positions:

The status message says "All pnematic valves closed" and the latest error message is about "V7 closed, N2 < 6.50e+01".

I found out that there was no autoburt happening for c1vac channels. I created an autoBurt.req file for the vac.db file and saved one snapshot. I also added the path of this file in autoburt/.requestfilelist . Let's see if autoburting starts by that for this file as well.

With this, I think we can safely shutdown acromag chassis. Hopefully, the relays are configured such that the valves are nominally closed in absence of a control signal. After the chassis is shut down, wwe can shutdown C1VAC by:

sudo shutdown

[Chub, Jordan]

At the 1x8 rack, the following were switched off on their respective front panels:

PTP2 & PTP3 Controller
MKS Gauge controller
PRP Gauge Controller
G2P316a & b Controllers
Sorenson
Serial Device Server
Both UPS's

Powered off from back of unit:

TP1 Controller
Acromag chassis

TP2 and 3 controllers were unplugged from respective power strips (labeled C2 and C3)

C1vac and the laptop at the workstation were shut down

Manual Gate valve was closed

ELOG V3.1.3-