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New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Typeup Category Subject
  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.

 

  16547   Thu Jan 6 13:54:28 2022 KojiUpdateCDSYearly DAQD fix 2022!

Just restarting all the c1sus2 models fixed the issue. (Attachment 1)

SUS2 ADC1 CH21 is saturated. I'm not yet sure if this is the electronics issue or the ADC issue.
SUS2 ADC1 CH10 also has large offset. This should also be investiagted.

Attachment 1: Screenshot_2022-01-06_13-57-40.png
Screenshot_2022-01-06_13-57-40.png
  16548   Thu Jan 6 14:08:14 2022 KojiUpdateCDSMore BHD SUS screens added to sitemap

More BHD SUS screens added to sitemap (Attachment 1)

Attachment 1: Screenshot_2022-01-06_14-06-15.png
Screenshot_2022-01-06_14-06-15.png
  16549   Thu Jan 6 15:10:38 2022 KojiUpdateSUSITMX Chamber work

[Anchal, Koji]

=== Summary ===
- ITMX SD OSEM migration done
- LO1 OSEM insertion and precise adjustment (part 1) done
- LO1 POS/PIT/YAW/SD motions were damped


=== General Remarks ===
- 15:00 Entered into ITMX.
- We were equipped with N95 and took physical distance as much as possible.
- 17:00 Temporarily came out from the lab.
- 18:30? Came into the chamber again
- 20:00 Sus damped. OSEM work continues
- 21:00 OSEM installation work done. Exit.

=== ITMX SD OSEM position swap ===
- Moved the LO1 suspension to the center of the chamber
- Removed the ITMX SD OSEM from the right side (west side) and tried to move it to the other side.
- Noted that the open light output of the ITMX SD was 908 at the output of the SDSEN filter module. So the half-light target is 454. These numbers include the "cnt2um" calibration of 0.36. That means the open light raw ADC count was supposed to be 2522.

- The OSEM set screw (silver plated, with a plunger) was removed from the old position. We first tried to recycle it to the other side, but it didn't go into the thread with fingers. After making ourselves convinced that the threaded hole was identical for both sides, we decided to put the new identical plunger set screw with an Allen-key was used to put it in and it went in!
- Now the ITMX SD OSEM was inserted from the east side. Once we saw some shadow on the OSEM signal, the SD damping was turned on with the previous setting. And this successfully damped the side motion. ⭕️
- A bit finer adjustment has been done. After a few trials, we reached the stable output of ~400. Considering the temporary leveling of the table, we decided this is enough for now ⭕️. The set screw was tightened.
- To make the further work safer w.r.t the ITMX magnets, Anchal fastened the EQ stops of the ITMX sus except for the bottom four.
- Photo: [Attachment 1]

=== LO1 OSEM installation ~ wiring ===
- Now LO1 was moved back to the planned position.
- For the wiring, we (temporarily) clamped the in-vac DSUB cables to the stack table with metal clamps.
- Started plugging the OSEMs into the DSUB cables.
- Looking at the LO1-1 cable from the mating side with the longer side top: The top-right pin of the female connector is Pin1 as usual. From right to left LL / UR / UL coils were inserted one by one while looking at the OSEM PD signals.
- LO1-2 cable has the LR / SD coils (from the right to the left) were connected.
- Photo: [Attachment 2]

- LO1 Open light levels (raw ADC counts) the 2nd number is the target half-light level

  • UL 27679 (-> 13840)
  • UR 29395 (-> 14697)
  • LR 30514 (-> 15257)
  • LL 27996 (-> 13998)
  • SD 26034 (-> 13017)

=== RTS Filter implementation ===

- Anchal copied the filter module settings from other suspensions.
- We also implemented the simple input and output matrices.

=== LO1 OSEM insertion ===

- We struggled to make the suspension freely swinging with the OSEMs inserted.

- It seemed that the magnets were sucked to the OSEMs due to magnetic components.
- It turned out that the OSEMs were not fastened well and not seated in the holder plates.
- Once this was fixeded, we found that the mirror height is too high for the given OSEM heights.
  The suspension height (or the OSEM height should be decided with the OSEMs not inserted but fully fastened to prevent misalignment of them.

- Decided to lift up the OSEM plates in situ.
- Soon we found that the OSEM holder plates are not fastened at all [Attachment 3 arrows]
- The plates were successfully lifted up and
the suspension became much more freely swinging even with the OSEMs inserted. ⭕️

=== LO1 damping and more precise OSEM insertion ===

- Once the OSEMs were inserted to the light level of 30~70%, we started to try to dampen the motion. The side damping was somewhat successful, but the face ones were not.
- We checked the filters and found the coil output filters didn't have the alternating signs.
- Once the coil signs were corrected, the damping became more straight forward.
- And the robust damping allowed us the fine-tuning of the OSEM insertion.

- In the end, what we had for the light levels were

  • UL 14379 (52%)
  • UR 14214 (48%)
  • LR 14212 (47%)
  • LL 12869 (46%)
  • SD 14358 (55%)

The damping is working well. [Attachment 4]


Post continues at 40m/16552.

Attachment 1: PXL_20220107_044739280.MP.jpg
PXL_20220107_044739280.MP.jpg
Attachment 2: PXL_20220107_044958224.jpg
PXL_20220107_044958224.jpg
Attachment 3: PXL_20220107_044805503.NIGHT.jpg
PXL_20220107_044805503.NIGHT.jpg
Attachment 4: Screen_Shot_2022-01-06_at_20.54.04.png
Screen_Shot_2022-01-06_at_20.54.04.png
  16550   Thu Jan 6 17:00:20 2022 YehonathanUpdateBHDSOS assembly -- LO2

{Paco, Yehonathan}

Today we suspended LO2 (E1800089) which Anchal has loaded into the thick optic adapter. Attachments 1,2 show the height and roll balance adjustments.

I realigned the opLev setup and balanced the suspended mass. We figured that if we use 2 counterweights we will be 1 short. We decided to use 1 mass at the back of the adapter. This has the additional advantage that the Viton tip on lower back EQ stop can touch it and act normally. The optic was successfully balanced in this way. Attachment 3 shows the motion spectra on the QPD. There are major peaks at 712 mHz, 854 mHz, 876 mHz, and 996 mHz. As expected using only 1 counterweight raised the center of mass and lowered the pitch resonance frequency. The optic was locked keeping the alignment fixed on the center of the QPD, OSEMs were inserted and the SOS tower was engraved.

We should apply some glue to the counterweight to prevent it from spinning on the setscrew.

Attachment 1: LO2_roll_balance.png
LO2_roll_balance.png
Attachment 2: LO2_magnet_height.png
LO2_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16551   Thu Jan 6 17:16:51 2022 YehonathanUpdateBHDUsing Peek screws/nuts

There were several cases where the long EQ stops didn't perform as expected.

In one type of case, we used a counterweight at the front of the adapter but not in the back leaving a recess where the lower back EQ stop should touch.

In the other type, a recess in the thick optics adapter prevented the upper EQ stop from touching the adapter. In the first thick optic, the screw was screw barely scratched the recess' corner. In the second case, it didn't touch it at all.

In the last group meeting, we discussed using Peek screws (made out of plastic) to prevent metal on metal bumping when the EQ can touch the adapter and Peek nuts when it doesn't to increase its impact area.

Mcmaster has 1.5" long 1/4-20 screws (part number 98885A131) that will fit well in the OSEM plates. We can order 20 of those.

The biggest Peek nuts on Mcmaster however are not big enough (7/16" wide) to cover the entire bottom recess area which is 0.5" wide (they are good enough for the top recess area in the thick adapter optic design). Koji suggested that we can use a big Peek washer for that purpose that can be held between nuts. We should then order 10 Peek nuts (98886A813) and 1 package of 10 Peek washers (0.63" OD) (93785A600).

  16553   Thu Jan 6 22:18:47 2022 KojiUpdateCDSSUS screen debugging

Indicated by the red arrow:
Even when the side damping servo is off, the number appears at the input of the output matrix

Indicated by the green arrows:
The face magnets and the side magnets use different ADCs. How about opening a custom ADC panel that accommodates all ADCs at once? Same for the DAC.

Indicated by the blue arrows:
This button opens a custom FM window. When the pitch gain was modified with a ramping time, the pitch and yaw gain grows at the same time even though only the pitch gain was modified.

Indicated by the orange circle:
The numbers are not indicated here, but they are input-related numbers (for watchdogging) rather than output-related numbers. It is confusing to place them here.

Attachment 1: Screen_Shot_2022-01-06_at_18.03.24.png
Screen_Shot_2022-01-06_at_18.03.24.png
  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.

  16556   Fri Jan 7 17:59:45 2022 YehonathanUpdateBHDSOS assembly -- SR2

{Yehonathan, Paco}

{Paco, Yehonathan}

Today we suspended SR2 (E1800089) which Anchal has loaded into the thick optic adapter. Attachments 1,2 show the height and roll balance adjustments.

I realigned the opLev setup and balanced the suspended mass. Attachment 3 shows the motion spectra on the QPD. There are major peaks at 723 mHz, 832 mHz, and 996 mHz. I inserted OSEMs and tightened them in place. I adjusted the OSEM plates to make sure the magnets are at the center of the OSEMs, then I tightened the OSEM plates to the SOS tower.

The optic was locked keeping the alignment fixed on the center of the QPD.

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

Attachment 1: SR2_roll_balance.png
SR2_roll_balance.png
Attachment 2: SR2_magnet_height.png
SR2_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16557   Fri Jan 7 18:24:25 2022 KojiUpdateBHDSOS assembly -- SR2

Vacseal in the freezer. It could have been expired sooooo many years ago, We need some cure testing.

Can you release the part numbers of the ordered components (and how/where to use them), so that we can incorporate them into the CAD model?

Quote:

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

  16558   Fri Jan 7 18:28:13 2022 KojiUpdateBHDPR2 Sat Amp has a bad channel

Leave the unit to me. I can look it at on Mon. For a while, you can take a replacement unit from the electronics stack.

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

  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?

 

  16561   Mon Jan 10 14:00:44 2022 not KojiUpdateBHDSOS assembly -- SR2

Yes,

For the thin optics adapter design, we want Peek 1/4-20 screw (part # 98885A131) to replace the lower back long EQ stop. On it, we will have a Peek washer (part # 93785A600) fastened between two Peek nuts (part #98886A813).

For the thick optics adapter design, we want Peek 1/4-20 screw (part # 98885A131) to replace both the upper and lower back EQ stop. On the upper stop, we need a single Peek nut (part #98886A813).

I will cure-test the Vacseal.

Quote:

Vacseal in the freezer. It could have been expired sooooo many years ago, We need some cure testing.

Can you release the part numbers of the ordered components (and how/where to use them), so that we can incorporate them into the CAD model?

Quote:

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

 

  16563   Mon Jan 10 15:45:55 2022 PacoUpdateElectronicsITMY feedthroughs and in-vac cables installed - part I

The ITMY 10" flange with 10 DSUB-25 feedthroughs has been installed with the cables connected at the in-vac side.  This is the first of two flanges, and includes 5 cables ordered vertically in stacks of 3 & 2 for [[OMC-DCPDs, OMC-QPDs, OMC-PZTs/Pico]] and [[SRM1, SRM2]] respectively from right to left. During installation, two 12-point silver plated bolts were stripped, so Chub had to replace them.

  16564   Mon Jan 10 15:59:46 2022 KojiUpdateBHDPR2 Sat Amp has a bad channel

The issue was present in the cable between the small adapter board and the rear panel. The cable and the Dsub 25 connectors were replaced. The removed parts were resoldered. Did the basic test of the channel.


Attachment 1: I cleaned up the area of the PD3 circuit of S2100556 and checked the voltage when the circuit was energized. The PD photocurrent line from the rear panel had S2100556 even with R25 removed. So the problem was between the rear panel to the outer side of R25. I've started to remove the cables to localize the issue and found that the issue disappeared when the ribbon cable was removed.

Attachment 2: I didn't investigate how the ribbon cable was bad. It was just trashed. The cable and the 25pin Dsub connectors were replaced and the line in question looked normal.

Attachment 3: All the components removed were stuffed again. The I/V-output of the circuit showed a 0.7mV offset but it seemed within the normal range. By touching R25 with a finger made it up to ~10mV as the other channels do. BTW: For 1000pF cap (C10) I used a stock 1000pF cap (KEMET, C330C102JDG5TA, 5%, 1kV, C0G) instead of nominal one (KEMET, C317C102G1G5TA,  2%, 100V, C0G).

Attachment 4: Noticed that the jumpers for shield grounding were missing. So they were installed (Attachment 5). This jumper is connected to Pin13. This line becomes Pin1 of the Dsub25 sat-amp cable because of the adapter board D2100148. The sat amp cable is D2100675. Hmm. In fact, this line does not touch the shield anywhere (unlike the aLIGO case). So only the chassis provides the cable shielding, no matter how the jumpers are connected or not connected.

Attachment 6: Final state of the circuit

Attachment 1: trouble_shoot1.jpg
trouble_shoot1.jpg
Attachment 2: trouble_shoot2.jpg
trouble_shoot2.jpg
Attachment 3: S2100556_PD3.jpg
S2100556_PD3.jpg
Attachment 4: shield_grounding_before.jpg
shield_grounding_before.jpg
Attachment 5: shield_grounding_after.jpg
shield_grounding_after.jpg
Attachment 6: S2100737.jpg
S2100737.jpg
  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.

 

  16568   Tue Jan 11 09:53:14 2022 not KojiUpdateBHDSOS assembly -- Peek screws and nuts

I handed the Peek parts we got from McMaster to Jordan for C&B.

  16569   Tue Jan 11 10:23:18 2022 PacoUpdateElectronicsITMY feedthroughs and in-vac cables installed - part II

[Paco, Chub]

The ITMY 10" flange with 4 DSUB-25 feedthroughs has been installed with the cables connected at the in-vac side. This is the second of two flanges, and includes 4 cables ordered vertically in stacks of 2 & 2 for [[AS1-1, AS1-2, AS4-1, AS4-2]] respectively. No major incidents during this one, except maybe a note that all the bolts were extremely dirty and covered with gunk, so we gave a quick swipe with wet cloths before reinstalling them.

  16570   Tue Jan 11 10:46:07 2022 TegaUpdateCDSSUS screen debugging

Seen. Thanks.

Red Arrow: The channel was labeled incorrectly as INMON instead of OUTPUT

Green Arrow: OK, I will create a custom medm screen for this.

Blue arrow: Hmm, OK I will look into this. Doing this work remotely is a pain as the medm response is quite slow for poking around.

Orange circle: OK, I'll move this to the left side of the line.

Note to self: I also noticed another error on the side (LPYS blue box just b4 the sum). The channel is pointing to YAW instead of the side, so needs to be fixed as well.

Quote:

Indicated by the red arrow:
Even when the side damping servo is off, the number appears at the input of the output matrix

Indicated by the green arrows:
The face magnets and the side magnets use different ADCs. How about opening a custom ADC panel that accommodates all ADCs at once? Same for the DAC.

Indicated by the blue arrows:
This button opens a custom FM window. When the pitch gain was modified with a ramping time, the pitch and yaw gain grows at the same time even though only the pitch gain was modified.

Indicated by the orange circle:
The numbers are not indicated here, but they are input-related numbers (for watchdogging) rather than output-related numbers. It is confusing to place them here.

 

  16571   Tue Jan 11 10:58:58 2022 TegaUpdateSUSTemporary watchdog

Started working on this. First created a git repo for tracking https://git.ligo.org/40m/susaux.git

I have looked through the folder to see what needs doing and I think I know what needs to be done for the final case by just following the same pattern for the other optics, which I am listing below

- Create database file for the BHD optics, say C1_SUS-AUX_LO1.db by copying another optic database file say C1_SUS-AUX_SRM. Then replace the optic name.

- Insert a new line "C1:SUS-LO1_LATCH_OFF" in the file autoBurt_watchdogs.req

- Populate the file autoBurt.req with the appropriate channels for LO1

- Populate the file C1SUSaux_post.sh with the corresponding commands for LO1

- Add the line dbLoadDatabase("/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db") to the file C1SUSaux.cmd

 

For the temporary watchdog, we comment everything I have just talked about, and do only what come next.

My question is the following:

I understand that we need to use the OUT16 slow channel as a temporary watchdog since we don't currently have access to the slow channels bcos the Acromag units have not been installed. My guess from Koji's instructions is that we need to update the channels in the last two fields "INPA" and "INPB" below

record(calc,"C1:SUS-LO1_UL_CALC")
{
        field(DESC,"ANDs Enable with Watchdog")
        field(SCAN,"1 second")
        field(PHAS,"1")
        field(PREC,"2")
        field(HOPR,"40")
        field(LOPR,"-40")
        field(CALC,"A&B")
        field(INPA,"C1:SUS-LO1_UL_COMM  PP  NMS")
        field(INPB,"C1:SUS-LO1_LATCH_OFF  PP  MS")
}

Suppose we replace the channel for INPA with C1:SUS-LO1_ULCOIL_OUT16, what about INPB. Is this even the right thing to do as I am just guessing here?

 

  16573   Tue Jan 11 13:43:14 2022 KojiUpdateSUSTemporary watchdog

I don't remember the syntax of the db file, but here this calc channel computes A&B. And A&B corresponds to INPA and INPB.

        field(CALC,"A&B")
        field(INPA,"C1:SUS-LO1_UL_COMM  PP  NMS")
        field(INPB,"C1:SUS-LO1_LATCH_OFF  PP  MS")

What is this LATCH doing?

 

  16574   Tue Jan 11 14:21:53 2022 PacoUpdateElectronicsBS feedthroughs and in-vac cables installed

[Paco, Yehonathan, Chub]

The BS chamber 10" flange with 4 DSUB-25 feedthroughs has been installed with the cables connected at the in-vac side. This is the second of two flanges, and includes 4 cables ordered vertically in stacks of 2 & 2 for [[LO2-1, LO2-2, PR3-1, PR3-2]] respectively.

  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
LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PRS_Trans_Calc.ipynb.zip
  16582   Thu Jan 13 16:08:00 2022 YehonathanUpdateBHDgluing magnets after AS1/4 misfortune

{Yehonathan, Anchal, Paco}

In the cleanroom, we removed AS1 and AS4 from their SOS towers. We removed the mirrors from the adapters and put them in their boxes. The broken magnets were collected from the towers and their surfaces were cleaned as well as the magnet sockets on the two adapters and on the side block from where the magnets were knocked off.

We prepared our last batch of glue (more glue was ordered three days ago) and glue 2 side magnets and 2 face magnets. We also took the chance and apply glue on the counterweights on the thick optic adapters so there is no need to look for alternatives for now.

The peek screws and nuts were assembled on the thick optics SOS towers instead of the metal screws and nuts that were used as upper back EQ stops.

  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
LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PR2_Trans_Calc.ipynb.zip
  16584   Fri Jan 14 03:07:04 2022 KojiUpdateBHDPR2 transmission calculation

I opened the notebook but I was not sure where you have the loss per bounce for the arm cavity.

    PRC_RT_Loss = 2 * PR3_T + 2 * PR2_T + 2 * Arm_Cavity_Finesse * ETM_T + PRM_T

Do you count the arm reflection loss to be only 2 * 13ppm * 450 = 1.17%?

  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
LO_power_vs_PR2_transmission.pdf
Attachment 2: PRC_Gain_vs_PR2_transmission.pdf
PRC_Gain_vs_PR2_transmission.pdf
Attachment 3: PR2_Trans_Calc.ipynb.zip
  16588   Fri Jan 14 14:04:51 2022 PacoUpdateElectronicsRFSoC 2x2 board arrived

The Xilinx RFSoC 2x2 board arrived right before the winter break, so this is kind of an overdue elog. I unboxed it, it came with two ~15 cm SMA M-M cables, an SD card preloaded with the ARM processor and a few overlay jupyter notebooks, a two-piece AC/DC adapter (kind of like a laptop charger), and a USB 3.0 cable. I got a 1U box, lid, and assembled a prototype box to hold this board, but this need not be a permanent solution (see Attachment #1). I drilled 4 thru holes on the bottom of the box to hold the board in place. A large component exceeds the 1U height, but is thin enough to clear one of the thin slits at the top (I believe this is a fuse of some sort). Then, I found a brand new front panel, and drilled 4x 13/32 thru holes in the front for SMA F-F connectors.

I powered the board, and quickly accessed its tutorial notebooks, including a spectrum analyzer and signal generators just to quickly check it works normally. The board has 2 fast RFADCs and 2 RFDACs exposed, 12 and 14 bit respectively, running at up to 4 GSps.

Attachment 1: PXL_20220114_211249499.jpg
PXL_20220114_211249499.jpg
  16589   Fri Jan 14 17:33:10 2022 YehonathanUpdateBHDAS4 resurrection

{Yehonathan, Anchal}

Came this morning, the gluing of the magnets was 100% successful. Side blocks, counterweights were assembled. We suspend AS4 and adjust the roll balance and the magnet height (attachments 1,2). OpLev was slightly realigned.

The pitch was balanced. We had to compensate for the pitch shift due to the locking of the counterweights. Once we got good pitch balance, the motion spectrum was taken (attachment 3). Major peaks are at 755mHz, 953mHz, 1040mHz.

Previous peaks were 755mHz, 964mHz, and 1.062Hz so not much has changed. We pushed back the OSEMs, adjusted OSEM plate and locked it tightly. We lock the EQ stops and transfer AS4 to the vacuum chamber in foil. We open the foil inside the chamber. No magnets were broken. Everything seems to be intact. We connect the OSEMs to CDS.

Attachment 1: AS4_roll_balance2.png
AS4_roll_balance2.png
Attachment 2: AS4_magnet_height2.png
AS4_magnet_height2.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16597   Wed Jan 19 14:41:23 2022 KojiUpdateBHDSuspension Status

Is this the correct status? Please directly update this entry.


LO1 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
LO2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
AS1 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]

AS4 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
PR2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
PR3 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]
SR2 [Glued] [Suspended] [Balanced] [Placed In Vacuum] [OSEM Tuned] [Damped]


Last updated: Fri Jan 28 10:34:19 2022

  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
PR2transmissionSelectionAnalysis.pdf PR2transmissionSelectionAnalysis.pdf PR2transmissionSelectionAnalysis.pdf PR2transmissionSelectionAnalysis.pdf
Attachment 2: PR2_Trans_Calc.ipynb.zip
  16599   Wed Jan 19 18:15:34 2022 YehonathanUpdateBHDAS1 resurrection

Today I suspended AS1. Anchal helped me with the initial hanging of the optics. Attachments 1,2 show the roll balance and side magnet height. Attachment 3 shows the motion spectra.

The major peaks are at 668mHz, 821mHz, 985mHz.

For some reason, I was not able to balance the pitch with 2 counterweights as I did with the rest of the thin optics (and AS1 before). Inserting the weights all the way was not enough to bring the reflection up to the iris aperture that was used for preliminary balancing. I was able to do so with a single counterweight (attachment 4). I'm afraid something is wrong here but couldn't find anything obvious. It is also worth noting that the yaw resonance 668mHz is different from the 755mHz we got in all the other optics. Maybe one or more of the wires are not clamped correctly on the side blocks?

The OSEMs were pushed into the OSEM plate and the plates were adjusted such that the magnets are at the center of the face OSEMs. The wires were clamped and cut from the winches. The SOS is ready for installation.

Also, I added a link to the OSEM assignments spreadsheet to the suspension wiki.

I uploaded some pictures of the PEEK EQ stops, both on the thick and thin optics, to the Google Photos account.

Attachment 1: AS1_roll_balance2.png
AS1_roll_balance2.png
Attachment 2: AS1_magnet_heigh2.png
AS1_magnet_heigh2.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
Attachment 4: IMG_6324.JPG
IMG_6324.JPG
  16600   Wed Jan 19 21:39:22 2022 TegaUpdateSUSTemporary watchdog

After some work on the reference database file, we now have a template for temporary watchdog implementation for LO1 located here "/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db".

Basically, what I have done is swap the EPICS asyn analog input readout for the COIL and OSEM to accessible medm channels, then write out watchdog enable/disable to coil filter SW2 switch. Everything else in the file remains the same. I am worried about some of the conversions but the only way to know more is to see the output on the medm screen.

To test, I restarted c1su2 but this did not make the LO1 database available, so I am guessing that we also need to restart the c1sus, which can be done tomorrow.

  16601   Thu Jan 20 00:26:50 2022 KojiUpdateSUSTemporary watchdog

As the new db is made for c1susaux, 1) it needs to be configured to be read by c1susaux 2) it requires restarting c1susaux 3) it needs to be recorded by FB 4) and restartinbg FB.
(^-Maybe not super exact procedure but conceptually like this)

cf.
https://wiki-40m.ligo.caltech.edu/How_To/Add_or_rename_a_daq_channel

 

  16602   Thu Jan 20 01:48:02 2022 KojiUpdateBHDPR2 transmission calculation updated

IMC is not such lossy. IMC output is supposed to be ~1W.

The critical coupling condition is G_PRC = 1/T_PRM = 17.7. If we really have L_arm = 50ppm, we will be very close to the critical coupling. Maybe we are OK if we have such condition as our testing time would be much longer in PRMI than PRFPMI at the first phase. If the arm loss turned out to be higher, we'll be saved by falling to undercoupling.
When the PRC is close to the critical coupling (like 50ppm case), we roughly have Tprc x 2 and Tarm to be almost equal. So each beam will have 1/3 of the input power i.e. ~300mW. That's probably too much even for the two OMCs (i.e. 4 DCPDs). That's OK. We can reduce the input power by 3~5.

Quote:

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).

 

  16603   Thu Jan 20 12:10:51 2022 YehonathanUpdateBHDAS1 resurrection

I was wondering whether I should take AS1 down to redo the wire clamping on the side blocks. I decided to take the OpLev spectrum again to be more certain. Attachments 1,2,3 show 3 spectra taken at different times.

They all show the same peaks 744mHz, 810mHz, 1Hz. So I think something went wrong with yesterday's measurement. I will not take AS1 down for now. We still need to apply some glue to the counterweight.

Attachment 1: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
Attachment 2: FreeSwingingSpectra_div_20mV.pdf
FreeSwingingSpectra_div_20mV.pdf
Attachment 3: FreeSwingingSpectra_div_50mV.pdf
FreeSwingingSpectra_div_50mV.pdf
  16604   Thu Jan 20 16:42:55 2022 PacoUpdateBHDAS4 OSEMs installation - part 2

[Paco]

Turns out, the shifting was likely due to the table level. Because I didn't take care the first time to "zero" the level of the table as I tuned the OSEMs, the installation was b o g u s. So today I took time to,

a) Shift AS4 close to the center of the table.

b) Use the clean level tool to pick a plane of reference. To do this, I iteratively placed two counterweights (from the ETMX flow bench) in two locations in the breadboard such that I nominally balanced the table under this configuration to zome reference plane z0. The counterweight placement is of course temporary, and as soon as we make further changes such as final placement of AS4 SOS, or installation of AS1, their positions will need to change to recover z=z0.

c) Install OSEMs until I was happy with the damping. ** Here, I noticed the new suspension screens had been misconfigured (probably c1sus2 rebooted and we don't have any BURT), so quickly restored the input and output matrices.


SUSPENSION STATUS UPDATED HERE

  16606   Thu Jan 20 17:21:21 2022 TegaUpdateSUSTemporary watchdog

Temp software watchdog now operational for LO1 and the remaining optics!

Koji helped me understand how to write to switches and we tried for a while to only turnoff the output switch of the filters instead of the writing a zero that resets everything in the filter.

Eventually, I was able to move this effort foward by realising that I can pass the control trigger along multiple records using the forwarding option 'FLNK'. When I added this field to the trigger block, record(dfanout,"C1:SUS-LO1_PUSH_ALL"), and subsequent calculation blocks, record(calcout,"C1:SUS-LO1_COILSWa") to record(calcout,"C1:SUS-LO1_COILSWd"), everything started working right.

Quote:

After some work on the reference database file, we now have a template for temporary watchdog implementation for LO1 located here "/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db".

Basically, what I have done is swap the EPICS asyn analog input readout for the COIL and OSEM to accessible medm channels, then write out watchdog enable/disable to coil filter SW2 switch. Everything else in the file remains the same. I am worried about some of the conversions but the only way to know more is to see the output on the medm screen.

To test, I restarted c1su2 but this did not make the LO1 database available, so I am guessing that we also need to restart the c1sus, which can be done tomorrow.

 

  16607   Thu Jan 20 17:34:07 2022 KojiUpdateBHDV6-704/705 Mirror now @Downs

The PR2 candidate V6-704/705 mirrors (Qty2) are now @Downs. Camille picked them up for the measurements.

To identify the mirrors, I labeled them (on the box) as M1 and M2. Also the HR side was checked to be the side pointed by an arrow mark on the barrel. e.g. Attachment 1 shows the HR side up

Attachment 1: PXL_20220120_225248265_2.jpg
PXL_20220120_225248265_2.jpg
Attachment 2: PXL_20220120_225309361_2.jpg
PXL_20220120_225309361_2.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.

  16611   Fri Jan 21 12:46:31 2022 TegaUpdateCDSSUS screen debugging

All done (almost)! I still have not sorted the issue of pitch and yaw gains growing together when modified using ramping time. Image of custom ADC and DAC panel is attached.

 

Quote:

Seen. Thanks.

 
Quote:

Indicated by the red arrow:
Even when the side damping servo is off, the number appears at the input of the output matrix

Indicated by the green arrows:
The face magnets and the side magnets use different ADCs. How about opening a custom ADC panel that accommodates all ADCs at once? Same for the DAC.

Indicated by the blue arrows:
This button opens a custom FM window. When the pitch gain was modified with a ramping time, the pitch and yaw gain grows at the same time even though only the pitch gain was modified.

Indicated by the orange circle:
The numbers are not indicated here, but they are input-related numbers (for watchdogging) rather than output-related numbers. It is confusing to place them here.

 

 

Attachment 1: Custom_ADC_DAC_monitors.png
Custom_ADC_DAC_monitors.png
  16612   Fri Jan 21 14:51:00 2022 KojiUpdateBHDV6-704/705 Mirror now @Downs

Camille@Downs measured the surface of these M1 and M2 using Zygo.

Result of the ROC measurements:M1: ROC=2076m (convex)M2: ROC=2118m (convex)
Here are screenshots. One file shows the entire surface and the other shows the central 30mm.
Attachment 1: M1.PNG
M1.PNG
Attachment 2: M1_30mm.PNG
M1_30mm.PNG
Attachment 3: M2.PNG
M2.PNG
Attachment 4: M2_30mm.PNG
M2_30mm.PNG
  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
AS4_SUS_InpMat_Diagnolization_20220121.pdf
Attachment 2: AS4_FreeSwingData_PeakFitting_20220121.pdf
AS4_FreeSwingData_PeakFitting_20220121.pdf
  16616   Mon Jan 24 17:12:27 2022 ranaUpdateBHDAS4 Input Matrix Diagonalization performed.

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.

  16617   Mon Jan 24 17:58:21 2022 YehonathanUpdateBHDPR2 Suspension

I picked up the PR2 mirrors (labeled M1, M2) from Anchel's table and took them to the cleanroom. By inspection, I spotted some dust particles on M1. I wasn't able to remove them with clean air so I decided to use M2 which looked much cleaner. I wasn't able to discern any wedge angle on the optic. I inserted the optic into a thin optic adapter. The optic is thicker than I expected so I use long screws for the mirror clamping. I expect that the pitch balance will shift towards the front of the mirror so I assembled only 1 counterweight for now. The side blocks with wires in them were installed.

I engraved the SOS and installed the winches on it. Paco came in and helped me to hang the optic. Looking at the wire hanging angle I realize that 1 counterweight at the front is not enough. I install a second counterweight at the back and observe that I can cross the balancing point.

I locked the EQ stops. Suspension work continues tomorrow...

  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.

 

  16624   Tue Jan 25 18:37:12 2022 TYehonathanUpdateBHDPR2 Suspension

PR2's side magnet height was adjusted and its roll was balanced (attachment 1,2). I verified that the OpLev beam is still aligned. The pitch was balanced: First, using an iris for rough adjustment. Then, with the QPD. I locked the counterweight setscrew.

I turned off the HEPAs, damped PR2, and measured the QPD spectra (attachment 3). Major peaks are at 690mHz, 953mHz, and 1.05Hz. I screwed back the lower OSEM plate. The wires were clamped to the suspension block and were cut. Winch adapter plate removed. I wanted to push OSEMs into the OSEM plates but the wiki is down so I can't tell what was the plan. This will have to wait for tomorrow. Also here like with AS1 we need to apply glue to the counterweights.

Attachment 1: PR2_magnet_height.png
PR2_magnet_height.png
Attachment 2: PR2_roll_balance.png
PR2_roll_balance.png
Attachment 3: FreeSwingingSpectra_div_50mV.pdf
FreeSwingingSpectra_div_50mV.pdf
ELOG V3.1.3-