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ID Date Authorup Type Category Subject
  16475   Thu Nov 18 14:29:01 2021 KojiSummaryBHDBHD invac optics / opto-mechanics

I went through the optics list (in the BHD procurement google spreadsheet) and summarized how to build them.

The red ones are what we need to purchase. Because of the strange height of the LMR mounts, the post needs to have none half-integer inch heights.

They need to be designed as the usual SS posts are not designed to be vac compatible (not because of the material but the design like screw hole venting).

We also need to check how many clean forks we have.
-> The components were ordered except for the custom posts.

ssome partssss
Name Optic Mount Mount OH Post Post OH Fork / Base Base OH Total Height Notes
POP_SM5  Previous POYM1 / 2" Y1-2037-0 LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
POP_SM4 New CM254-750-E03 Thorlabs LMR1V Thorlabs 0.87 Newport 9953+PLS-T238 3.88 BA1V / BA2V 0.75 5.5  
BSOL1 New 2" VIS BB2-E02 LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
ITMYOL1 New 2" VIS BB2-E02 LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
ITMYOL2 New 2" VIS BB2-E02 LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
SRMOL1 New 2" VIS BB2-E02 LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
ASL LA1779-C Thorlabs or KPX217AR.33 Newport LMR2V Thorlabs 1.36 Custom Post 4.14 SS Fork 0 5.5  
GRY_SM1 Y2-2037-0 (in hand) DLC   DLC Post   DLC Fork   5.5  
BHDBS CVI (In hand) DLC 2 DLC Post   DLC Fork   5.5 (3" post for BHD)
LO3 Lambda (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
LO4 Lambda (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
AS3 Lambda (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
OMC1R3 Y1-1025-45P (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
OMC1R4 Y1-1025-45P (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
OMC2R3 Y1-1025-45P (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
OMC2R4 Y1-1025-45P (in hand) POLARIS-K1-2AH Thorlabs 1 Custom Post 4.5 SS Fork 0 5.5 (3" post for BHD)
OMC1R1 Y1-1025-45P (in hand) LMR1V Thorlabs 0.87 Custom Post 4.63 SS Fork 0 5.5 (3.13" post for BHD)
OMC2R1 NB1-K14 Thorlabs LMR1V Thorlabs 0.87 Custom Post 4.63 SS Fork 0 5.5 (3.13" post for BHD)


  16490   Mon Dec 6 14:26:52 2021 KojiUpdateVACPumping down the RGA section

Jordan reported that the RGA section needs to be pumped down to allow the analyzer to run at sufficiently low pressure (P<1e-4 torr).
The RGA section was pumped down with the TP2/TP3. The procedure is as listed below.
If the pressure go up to P>1e-4 torr, we need to keep the pump running until the scan is ready.

### Monitor / Control screen setup ###
1. On c1vac: cd /cvs/cds/caltech/target/c1vac/medm
2. medm -x C0VAC_MONITOR.adl&
3. RGA section (P4) 3.6e-1 torr / P3/P2 still atm.
4. medm -x C0VAC_CONTROL.adl

### TP2/TP3 backing ###
5. Turn on AUX RP with the circuit breaker hanging on the AC.
6. Open manual valve for TP2/3/ backing / PTP2/3 ~ 8torr

### TP2/TP3 starting ###
7. Turned on TP2/TP3 with the Standby OFF

### Pump down the pump spool ###
8. Connect manual RP line (Quick Connect)
9. Turned on RP1/RP3 -> quickly reached 0.4 torr
10. Open V6 for pump spool pumping -> Immediately go down to sufficiently low pressure for TP2/TP3.
(10.5 I had to close V6 at this point)
11. Open V5 to start pumping pump spool with TP3 (TP2 still stand by) -> P3 immediately goes down below 1e-4 torr. This automatically closed V6 because of the low pressure of P3 (interlocking)

### Pump down the RGA section ###
12. Open VM3 to pump down RGA section -> P4 goes down to <1e-4 torr
13. P2 is still 2e-3. So decided to open V4 to use TP2 (now it's ready) too. -> Saturated at 1.7e-3

### Shutting down ###
14. Close VM3
15. Close V4/V5 to isolate TP2/TP3
16. Stop TP2/TP3 -> Slowing down
17. Stop RP1/RP3
18. Close the manual valves for TP2/3/ backing
19. Stop AUX RP with the circuit breaker hanging on the AC.

  16493   Tue Dec 7 13:12:50 2021 KojiUpdateVACPumping down the RGA section

So that Jordan can run the RGA scan this afternoon, I ran TP3 and started pumping down the RGA section.

- Same 1~4
- Same 5
- 6 Opened only the backing path for TP3
- 7 Turned on TP3 only

- TP3 reached the nominal full speed @75kRPM

- 11 Opened V5 to pump the pump spool -> Immediately reached P3<1e-4
- 12 Opened VM3 to pump the RGA section -> Immediately reached P4<1e-4

The pumps are kept running. I'll come back later to shut down the pumps.
=> Jordan wants to heat the filament (?) and to run the scan tomorrow.
So we decided to keep TP3 running overnight. I switched TP3 to the stand-by mode (= lower rotation speed @50kRPM)


  16501   Fri Dec 10 19:22:01 2021 KojiUpdateVACPumping down the RGA section

The scan result was ~x10 higher than the previously reported scan on 2020/9/15 (https://nodus.ligo.caltech.edu:8081/40m/15570), which was sort of high from the reference taken on 2018/7/18.

This just could mean that the vacuum level at the RGA was x10 high.
We'll just go ahead with the vacuum repair and come back to the RGA once we return to "vacuum normal".

Meanwhile, I asked Jordan to turn off the RGA to make it cool down. I shut off RGA section and turned TP2 off.

  16502   Fri Dec 10 21:35:15 2021 KojiSummarySUSVertex SUS DAC adapter ready

4 units of Vertex SUS DAC adapter (https://dcc.ligo.org/LIGO-D2100035) ready.





The units are completely passive right now and has option to extend to have a dewhitening board added inside.
So the power switch does nothing.

Some of the components for the dewhitening enhancement are attached inside the units.



Attachment 1: PXL_20211211_053155009.jpg
Attachment 2: PXL_20211211_053209216.jpg
Attachment 3: PXL_20211211_050625141-1.jpg
  16510   Wed Dec 15 17:44:18 2021 KojiSummaryBHDPart VIII of BHR upgrade - Placed LO1

If ITMX already has another side magnet, we can migrate the side OSEM of ITMX to the other side. This way, the interference of the OSEMs can be avoided.

  16515   Thu Dec 16 15:54:08 2021 KojiUpdateElectronicsITMX feedthroughs and in-vac cables installed

Thanks for the installation.

With regard to the connector convention, let's use the attached arrangement so that it will be consistent with the existing flange DSUB configuration. Not a big deal.


Attachment 1: PXL_20211216_235056582.jpg
  16516   Thu Dec 16 17:41:12 2021 KojiUpdateBHDCoil driver test failed for S2100619-v1

Good catch. It turned out that the both + and - side of the output stages for CH2 were oscillating at ~600kHz. If I use a capacitance sticks to touch arbitrarily around the components, it stops their oscillation and they stay calm.
It means that the phase margin becomes small while the circuit starts up.

I decided to increase the capacitances C6 and C20 (WIMA 150pF) to 330pF (WIMA FPK2 100V) and the oscillation was tamed. 220pF didn't stop them. After visually checked the signal behavior with an oscilloscope, the unit was passed to Anchal for the TF test.

The modification was also recorded in the DCC S2100619

Attachment 1: PXL_20211217_001735762.jpg
Attachment 2: PXL_20211217_001719345.jpg
Attachment 3: PXL_20211217_005344828.jpg
Attachment 4: PXL_20211217_010131027.PORTRAIT.jpg
Attachment 5: PXL_20211217_011423823.jpg
Attachment 6: HAMA_Driver_V4.pdf
  16519   Fri Dec 17 12:32:35 2021 KojiUpdateSUSRemaining task for 2021

Anything else? Feel free to edit this entry.

- SUS: AS1 hanging

- SUS: PR3/SR2/LO2 3/4" thick optic hanging

v Electronics chain check (From DAC to the end of the in-air cable / From the end of the in-air cable to the ADC)
[ELOG 16522]

- Long cable installation (4x 70ft)

- In-air cable connection to the flange

- In-vac wiring (connecting LO1 OSEMs)

- LO1 OSEM insertion/alignment

- LO1 Damping test


  16521   Fri Dec 17 19:16:45 2021 KojiUpdateBHDSOS assembly

We @40m do the convention of the arrow at the thinnest side & pointing the HR side, but nobody says Lambda does the same.

We can just remount the mirror without breaking the wires and adjust the pitching if you do it carefully.

Does this mean that the LO1 also likely to have the wedge pointing up? Or did you rotate the mirror to have the wedge reflection to be as horizontal as possible?

  16522   Fri Dec 17 19:19:42 2021 KojiUpdateSUSRemaining task for 2021

I had the fear that any mistake in the electronics chain could have been the show stopper.

So I quickly checked the signal assignments for the ADC and DAC chains.

I had initial confusion (see below), but it was confirmed that the electronics chains (at least for LO1) are correct.

Note: One 70ft cable is left around the 1Y0 rack


There are a few points to be fixed:

- It looks like the ADC/DAC card # assignment has been messed up.

CDS ADC0 -> Cable label ADC1 -> AA A1 -> ...
CDS ADC1 -> Cable label ADC0 -> AA A0 -> ...
CDS DAC0 -> Cable label DAC2 -> AI D2 -> ...
CDS DAC1 -> Cable label DAC0 -> AI D0 -> ...
CDS DAC2 -> Cable label DAC1 -> AI D1 -> ...
(What is going on here... please confirm and correct as they become straight forward)

Once this puzzle was solved I could confirm reasonable connections from the end of the 70 cables to the ADC/DAC.

- We also want to change the ADC card assignment. The face OSEM readings must be assigned to ADC1 and the side OSEM readings to ADC0.
  My system wiring diagram needs to be fixed accordingly too.
  This is because the last channel of the first ADC (ADC0) is not available for us and is used for DuoTone.

Attachment 1: PXL_20211218_030145356.MP.jpg
  16524   Sat Dec 18 00:56:14 2021 KojiUpdateBHDSOS assembly

Sad... We just need to check the wedge direction everytime, unfortunately.

Pencil: can you try to gently wipe it off with solvent & a swab? (IPA / Acetone)
If it does not come off in the end, it's all right to leave. Do we want to scribe the arrow mark? You need a diamond pen.

  16526   Mon Dec 20 13:52:01 2021 KojiUpdateBHDSOS assembly

LO1: No need to remove the pencil mark for the damping test. Until we see serious contamination on the LO1 optic, we don't need to take the optic off from the mount and clean it. If there is a chance of rehanging (because of a broken wire/etc), we do wipe the pencil mark.

Other optics: wipe the pencil mark as much as possible.

  16529   Tue Dec 21 16:35:39 2021 KojiUpdateVACITMX NW feedthru (LO1-1) connector pin bent

I've received a report that a pin of an ITMX NW feedthru connector was bent. (Attachment 1)
The connector is #1 (upper left) and planned to be used for LO1-1.

This is Pin25 and used for the PD K of OSEM #1. This means that Coil Driver #1 (3 OSEMs) uses this pin, but Coil Driver #2 (2 OSEMs) does not.

Anyways, I tried to fix it by bending it back. WIth some tools, it was straightened enough for plugging the cable connector. (Attachment 2)

It seemed that the pins were exceptionally soft compared to the ones used for usual DSUBs, probably because of the vacuum compatibility.
So it's better to approach the pins in parallel to the surface and not apply mating pressure until you are sure that all the 25pins are inserted in the counterpart holes.

Attachment 1: PXL_20211222_002019620.jpg
Attachment 2: PXL_20211222_003014068.jpg
  16532   Wed Dec 22 14:57:05 2021 KojiUpdateGeneralchiara local backup

chiara local backup of /cvs/cds has not been running since the move of chiara in Nov 19. The remote backup has not been taken since 2017.
The lack of the local backup was because of the misconfiguration of /etc/fstab.

It was fixed and now the backup disk was mounted. We'll see the backup script running tomorrow morning.
The backup disk is smaller than the main disk. So sooner or later, we will face the backup problem again.

localbackup script was crying because there was no backup disk.

backup>tail localbackup.log
2021-12-18 07:00:02,002 INFO       Updating backup image of /cvs/cds
2021-12-18 07:00:02,002 ERROR      External drive not mounted!!!
2021-12-19 07:00:01,146 INFO       Updating backup image of /cvs/cds
2021-12-19 07:00:01,146 ERROR      External drive not mounted!!!
2021-12-20 07:00:01,255 INFO       Updating backup image of /cvs/cds
2021-12-20 07:00:01,255 ERROR      External drive not mounted!!!
2021-12-21 07:00:01,361 INFO       Updating backup image of /cvs/cds
2021-12-21 07:00:01,361 ERROR      External drive not mounted!!!
2021-12-22 07:00:01,469 INFO       Updating backup image of /cvs/cds
2021-12-22 07:00:01,470 ERROR      External drive not mounted!!!

fstab had no entry for the backup disk.

backup>cat /etc/fstab
# /etc/fstab: static file system information.
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
# / was on /dev/sda1 during installation
UUID=972db769-4020-4b74-b943-9b868c26043a /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=a3f5d977-72d7-47c9-a059-38633d16413e none            swap    sw              0       0

#UUID="90a5c98a-22fb-4685-9c17-77ed07a5e000"    /media/40mBackup       ext4      defaults,relatime,commit=60       0         0

# CURRENT BACKUP DISK as of 2021/09/02
#UUID="1843f813-872b-44ff-9a4e-38b77976e8dc"    /media/40mBackup       ext4      defaults,relatime,commit=60       0         0

#fb:/frames      /frames nfs     ro,bg

# CURRENT MAIN DISK as of 2021/09/02
# UUID=92dc7073-bf4d-4c58-8052-63129ff5755b   /home/cds    ext4    defaults,relatime,commit=60    0   0
UUID="1843f813-872b-44ff-9a4e-38b77976e8dc"   /home/cds    ext4   defaults,relatime,commit=60    0   0

Checked the dev name of the disks and the UUIDs

backup>sudo lsblk
[sudo] password for controls:
sda      8:0    0 465.8G  0 disk
├─sda1   8:1    0 446.9G  0 part /
├─sda2   8:2    0     1K  0 part
└─sda5   8:5    0  18.9G  0 part [SWAP]
sdb      8:16   0   5.5T  0 disk
└─sdb1   8:17   0   5.5T  0 part /home/cds
sdc      8:32   0   3.7T  0 disk
└─sdc1   8:33   0   3.7T  0 part
sr0     11:0    1  1024M  0 rom
backup> sudo blkid
/dev/sda1: UUID="972db769-4020-4b74-b943-9b868c26043a" TYPE="ext4"
/dev/sda5: UUID="a3f5d977-72d7-47c9-a059-38633d16413e" TYPE="swap"
/dev/sdb1: UUID="1843f813-872b-44ff-9a4e-38b77976e8dc" TYPE="ext4"
/dev/sdc1: UUID="92dc7073-bf4d-4c58-8052-63129ff5755b" TYPE="ext4"

Added the fstab entry for the backup disk

media>cat /etc/fstab
# /etc/fstab: static file system information.
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
# / was on /dev/sda1 during installation
UUID=972db769-4020-4b74-b943-9b868c26043a /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=a3f5d977-72d7-47c9-a059-38633d16413e none            swap    sw              0       0

#UUID="90a5c98a-22fb-4685-9c17-77ed07a5e000"    /media/40mBackup       ext4      defaults,relatime,commit=60       0         0

# OLD BACKUP DISK as of 2021/09/02
#UUID="1843f813-872b-44ff-9a4e-38b77976e8dc"    /media/40mBackup       ext4      defaults,relatime,commit=60       0         0

# Current backup disk as of 2021/12/22
UUID="92dc7073-bf4d-4c58-8052-63129ff5755b"    /media/40mBackup       ext4      defaults,relatime,commit=60       0         0

#fb:/frames      /frames nfs     ro,bg

# CURRENT MAIN DISK as of 2021/09/02
# UUID=92dc7073-bf4d-4c58-8052-63129ff5755b   /home/cds    ext4    defaults,relatime,commit=60    0   0
UUID="1843f813-872b-44ff-9a4e-38b77976e8dc"   /home/cds    ext4   defaults,relatime,commit=60    0   0

  16534   Wed Dec 22 18:16:23 2021 KojiUpdateSUSRemaining task for 2021

The in-vacuum installation team has reported that the side OSEMs of ITMX and LO1 are going to be interfering if place LO1 at the planned location.
I confirmed that ITMX has the side magnet on the other side (Attachment 1 ITMX photo taken on 2016/7/21). So we can do this swap.

The ITMX side OSEM is sticking out most. By doing this operation, we will recover most of the space between the ITMX and LO1. (Attachment 2)

Attachment 1: ITMX_2016_07_21.jpg
Attachment 2: Screen_Shot_2021-12-22_at_18.03.42.png
  16535   Thu Dec 23 16:38:21 2021 KojiUpdateGeneralIs megatron down? (Re: chiara local backup)

The local backup seems working fine again. But I found that megatron is down and this is a real issue. This should be fixed at the earliest chance.

It seems that the local backup has been successfully taken this morning.

controls@nodus|backup> tail /opt/rtcds/caltech/c1/scripts/backup/localbackup.log
2021-12-19 07:00:01,146 INFO       Updating backup image of /cvs/cds
2021-12-19 07:00:01,146 ERROR      External drive not mounted!!!
2021-12-20 07:00:01,255 INFO       Updating backup image of /cvs/cds
2021-12-20 07:00:01,255 ERROR      External drive not mounted!!!
2021-12-21 07:00:01,361 INFO       Updating backup image of /cvs/cds
2021-12-21 07:00:01,361 ERROR      External drive not mounted!!!
2021-12-22 07:00:01,469 INFO       Updating backup image of /cvs/cds
2021-12-22 07:00:01,470 ERROR      External drive not mounted!!!
2021-12-23 07:00:01,594 INFO       Updating backup image of /cvs/cds
2021-12-23 07:19:55,560 INFO       Backup rsync job ran successfully, transferred 338425 files.

However, I noticed that the autoburt has been stalled since Dec 6 (I used to check how the backup is up-to-date using the autoburt snapshots)

Dec>ls -l
total 24
drwxr-xr-x 26 controls controls 4096 Dec  1 23:07 1
drwxr-xr-x 26 controls controls 4096 Dec  2 23:07 2
drwxr-xr-x 26 controls controls 4096 Dec  3 23:07 3
drwxr-xr-x 26 controls controls 4096 Dec  4 23:07 4
drwxr-xr-x 26 controls controls 4096 Dec  5 23:07 5
drwxr-xr-x 19 controls controls 4096 Dec  6 16:07 6

There are a bunch of errors in the log file as follows, but maybe this is not an issue

controls@nodus|burt> pwd
controls@nodus|burt> tail burtcron.log
!!!  ERROR !!! Target c1supepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1tstepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1x10epics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1aux Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1dcuepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1iscaux Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1iscepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1losepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1psl Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1susaux Snapshot file inconsistent with Request file

The real issue seems that megatron is down. It has a lot of house keeping jobs on corn including the N2 pressure alert.
This needs to be fixed at the earliest chance.

  16536   Fri Dec 24 16:49:41 2021 KojiUpdateGeneralIs megatron down? (Re: chiara local backup)

It turned out that the UPS installed on Nov 22 failed (cf https://nodus.ligo.caltech.edu:8081/40m/16479 ). As a fact, it was alive just for 2 weeks!

The APC UPS unit indicated F06. According to the manual (https://www.apc.com/shop/us/en/products/APC-Power-Saving-Back-UPS-Pro-1000VA/P-BR1000G), F06 means "Relay Welding" and can not be fixed by a user. Resetting the UPS eliminated the error, but I didn't want to have the same issue while no one is in the lab, I moved the megatron power source from the UPS to the power strip on 1Y7. So, megatron is currently vulnerable to a power glitch.

After the power cords were restored, megatron eventually recovered ssh terminals. I manually ran autoburt.cron at 16:50 so that the latest snapshot is taken.

Attachment 1: PXL_20211224_235652821.jpg
  16538   Sun Jan 2 20:46:46 2022 KojiUpdateSUSEnd SUS Electronics building

19:00~ Start working on the electronics bench

The following units were tested and ready to be installed. These are the last SUS electronics units and we are now ready to upgrade the end SUS electronics too.

40m End ADC Adapter Unit D2100016 / 2 Units (S2200001 S2200002)

40m End DAC Adapter Unit D2100647/ 2 Units (S2200003 S2200004)

These are placed on Tega's desk together with the vertex DAC adapters

0:30 End work

Attachment 1: PXL_20220103_081133119.jpg
  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
  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
  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
Attachment 2: PXL_20220107_044958224.jpg
Attachment 3: PXL_20220107_044805503.NIGHT.jpg
Attachment 4: Screen_Shot_2022-01-06_at_20.54.04.png
  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
  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?


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?

  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
Attachment 2: trouble_shoot2.jpg
Attachment 3: S2100556_PD3.jpg
Attachment 4: shield_grounding_before.jpg
Attachment 5: shield_grounding_after.jpg
Attachment 6: S2100737.jpg
  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(INPA,"C1:SUS-LO1_UL_COMM  PP  NMS")
        field(INPB,"C1:SUS-LO1_LATCH_OFF  PP  MS")

What is this LATCH doing?


  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%?

  16594   Tue Jan 18 18:19:22 2022 KojiSummaryBHDAS4 placed in ITMY Chamber, OSEMs connected

AS4 satellite amplifier D1002818 / D080276 troubleshoot

I dug into the circuit to see what/where things were wrong.

- UL saturation issue: The open light voltage at the TIA output (I-V out) was 10.4V. It seemed that the photocurrent of 86uA was simply a little too much for the transimpedance gain of 121kOhm. So the R18 was replaced to 100kOhm. This made the I-V out to be 8.6V and the ADC input count to be 28200 (Attachment 1). This modification was done on the unit S2100742 CH1 (LEFT CH1)

- Non responding LL issue: Now moved on to LL (LEFT CH2). The basic circuit test didn't reveal any problem. So the DSUB25 cables were swapped at the vacuum feedthru flange. The result is shown in Attachment 2. LL OSEM issue was moved to the 2nd ch of the right channel of the sat amp (CH6). This is means that the problem is somewhere in the vacuum chamber (including the vacuum feedthru). We need to check the in-vacuum cable and the OSEM. We can test the OSEM by swapping the position of the OSEM connector between LL and UL (for example).


Attachment 1: Screen_Shot_2022-01-18_at_17.48.16.png
Attachment 2: cable_swap.png
  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

  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)



  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.


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).


  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
Attachment 2: PXL_20220120_225309361_2.jpg
  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
Attachment 2: M1_30mm.PNG
Attachment 3: M2.PNG
Attachment 4: M2_30mm.PNG
  16629   Thu Jan 27 20:46:38 2022 KojiSummaryBHDPart III of BHR upgrade - Install PR2, balance, and attempt OSEM tuning
  • Started debugging D1002818 / S2100737 (8:30PM)
  • Confirmed the issue of the negative output of the UR sensor with the dummy OSEM connected at the air side of the ITMY chamber. Both PD Out and PD Mon have negative outputs.
  • The same issue remains when the dummy OSEM box is connected to the chassis with a short DB25M/F cable at the rack.
  • Started debugging the setup at the workbench.
    • CH1 TIA Output=-3.0V / CH2 (in question) TIA Output =-2.7V => No Problem
    • CH1 Whitening Out=+3.0V / CH2 Whitening Out=-1.4V => Problem
    • Resolder the components around whitening CH2 => no change
    • Remove AD822 and replace with a new one => CH2 Whitening OUt = +2.7V ==> Problem solved
    • PD1~3 channels of the left and right PCBs tested with the OSEM box ==> nearly +3V/-3V differential output (All Clear)
    • Chassis closing
  • Chassis restored in Rack 1Y1 and the normal output with the dummy OSEM box confirmed
  • Mission Completed (9:30PM)
  • Elog finished (9:40PM)
  • Case closed
Attachment 1: Screen_Shot_2022-01-27_at_20.33.56.png
Attachment 2: Screen_Shot_2022-01-27_at_21.30.16.png
  16631   Fri Jan 28 11:30:52 2022 KojiSummaryBHDPart III of BHR upgrade - PR2 OSEM finalized, reinsall LO1 OSEMs

All green! Great work, Team!

  16635   Tue Feb 1 15:33:28 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

I've summarized the optomechanics configuration for the in-vacuum aux small optics

It's not obvious here but the post for POP_SM4 is the stack of BA2V, Newport 9953, PLS-T238, LMR1V. The mirror is a CM254-750-E03 curved mirror. This should go on the suspension base. I hope I did not make a mistake there...

Attachment 1: Invac_opto_mechanics_v2.pdf
Invac_opto_mechanics_v2.pdf Invac_opto_mechanics_v2.pdf Invac_opto_mechanics_v2.pdf Invac_opto_mechanics_v2.pdf
  16640   Wed Feb 2 18:55:58 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

Here is more detail of the POP_SM4 mount assembly.

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

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

Attachment 1: Screen_Shot_2022-02-02_at_6.46.46_PM.png
  16641   Wed Feb 2 21:16:23 2022 KojiSummaryBHDOptomechanics configuration for the in-vacuum aux small optics

Asked Jordan to clean 2x 1.5" posts (0.5 dia) and a washer with 1" dia.


Attachment 1: PXL_20220203_050156031.jpg
  16651   Mon Feb 7 16:53:02 2022 KojiUpdateGeneralScheduled power outage recovery

I went to the X end and found it was warm. Turned out that not all the A/Cs were on. They were turned on now.

Attachment 1: PXL_20220208_001646282.jpg
Attachment 2: PXL_20220208_001657871.jpg
  16653   Wed Feb 9 13:55:05 2022 KojiUpdateGeneralBringing back CDS

Great recovery work and cleaning of the rebooting process.

I'm just curious: Did you observe that the c1sus2 cards have different numbering order than the previous along with the power outage/cycling?

  16656   Thu Feb 10 14:39:31 2022 KojiSummaryComputersNetwork security issue resolved

[Mike P / Koji / Tega / Anchal]

IMSS/LIGO IT notified us that "ILOM ports" of one of our hosts on the "114" network are open. We tried to shut down obvious machines but could not identify the host in question. So we decided to do a bit more systematic search of the host.

[@Network Rack]
- First of all, we disconnected the optical cables coming to the GC router while the ping is running on the AIRLIGO connected laptop (i.e. outside of the 40m network). This made the ping stopped. This means that the issue was definitely in the 40m.
- Secondly, we started to disconnect (and reconnect) the ethernet cables from the GC router one by one. We found that the ping response stops when the cable named "NODUS" was disconnected.

[@40m IFO lab]
- So we tracked the cable down in the 40m lab. After a while, we identified that the cable was really connected to nodus.

- Nodus was supposed to have one network connection to the martian network since the introduction of the bidirectional NAT router (rather than the old configuration with a single direction NAT router).

- In fact, the cable was connected to "non-networking" port of nodus. (Attachment 1). I guess the cable was connected like this long time, but somehow the ILOM (IPMI) port was activated along with the recent power cycling.

- The cable was disconnected at nodus too. (Attachment 2) And a tape was attached to the port so that we don't connect anything to the port anymore.

Attachment 1: PXL_20220210_220816955.jpg
Attachment 2: PXL_20220210_220827167.jpg
  16659   Thu Feb 10 19:03:23 2022 KojiUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

I came back to the 40m and started the investigation.

If I ping, it responds. But telnet (port 23) was rejected. I somehow tried ssh and it responds! I even could login to the host using usual password. Here is the prompt.

controls@nodus|~> ssh
controls@'s password:

controls@c1sus2:~ 0$

Oh no...

Looks like c1sus2 and the videomux have the IP address conflict.

Here are the useful ELOG links:



  16660   Thu Feb 10 19:46:37 2022 KojiUpdateGeneralScheduled power outage recovery - Locking mode cleaner(s)

== Assign new IP address to c1sus2 ==

cf: [40m ELOG 16398] [40m ELOG 16396]

- Shutdown c1sus2 (Oh, no. This killed c1lsc/c1sus/c1ioo... This should be taken care of later)

- Confirmed is not alive

- Go to chiara
- Modify /diskless/root/etc/hosts  c1sus2 c1sus2.martian

- Modify /etc/dhcp/dhcpd.conf

host c1sus2 {
  hardware ethernet 00:25:90:06:69:C2;

- Modify /var/lib/bind/martian.hosts

c1sus2          A
videomux        A

- Modify /var/lib/bind/martian.hosts/rev.113.168.192.in-addr.arpa

87            PTR    c1sus2.martian
92            PTR    videomux.martian

- Reload/restart bind9 / dhcpd. Run the following command

sudo service bind9 reload
sudo service isc-dhcp-server restart

- Restart c1sus2 and confirm if the IP address was actually changed

controls@c1sus2:~ 0$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:25:90:06:69:c2
          inet addr:  Bcast:  Mask:

== Restart c1lsc / c1sus /c1ioo ==

- Reboot c1lsc/c1sus/c1ioo

- Go to scripts/cds

- Run startC1LSC.sh and follow the instruction


  16661   Thu Feb 10 21:10:43 2022 KojiUpdateGeneralVideo Mux setting reset

Now the video matrix is responding correctly and the web interface shows up. (Attachment 1)

Also the video buttons respond as usual. I pushed Locking Template button to bring the setting back to nominal. (Attachment 2)

Attachment 1: Screenshot_2022-02-10_21-11-21.png
Attachment 2: Screenshot_2022-02-10_21-11-54.png
  16662   Thu Feb 10 21:16:27 2022 KojiSummaryCDSchiara resolv.conf wierdo

During the videomux debug, I noticed that the host name resolving on chiara didn't behave well. Basically I could not login to anything from chiara using host names.

I found that there was no /etc/resolv.conf. Instead, there is /etc/resolvconf directory.

According to my research, live resolv.conf is placed in /run/resolveconf/resolv.conf .

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

This 113.20 is directing an old "linux1" machine. Too much obsolete. If I modify this file as

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
search martian

Then the name resolving became reasonable. However, during rebooting / service resetting / etc, resolvconf -u command is executed and /run/resolveconf/resolv.conf is overridden, as indicated in the file.

I have modified /etc/resolvconf/resolv.conf.d/base to include and search martian . The latter was included but the former did not show up.

FInally I figured out that, after the resolv.conf is constructed from base and head files in /etc/resolvconf/resolv.conf.d/ , NetworkManager overrides the nameserver addresses.
The configuration was found in /etc/NetworkManager/system-connections/Wired\ connection\ 1 .

Here is the modified setting (dns entry was modified)

>sudo cat /etc/NetworkManager/system-connections/Wired\ connection\ 1
[sudo] password for controls:

id=Wired connection 1




>cat /etc/resolvconf/resolv.conf.d/base
search martian
# See Also /etc/NetworkManager/system-connections/Wired\ connection\ 1

So complicated...

  16663   Thu Feb 10 21:51:02 2022 KojiUpdateCDS[Solved] Huge random numbers flowing into ETMX/ETMY ASC PIT/YAW

Huge random numbers are flowing into ETMX/ETMY ASC PIT/YAW. Because of this, I could not damp the ETMX/ETMY suspension at the beginning during the recovery from rebooting. (Attachment 1)
By turning off the output of the ASC filters, the mirrors were successfully damped.

Looking at the FE model view of the end RTSs, there were two possibilities: (Attachment 2)

- They are coming from RFM connection
- They are coming from ASXASY

ASX/ASY are not active and I could not see anything producing these numbers. Burtrestore didn't help.

The possibility was something at the other side of the RFM, or corruption of the RFM signal.

- Looking at the RFM model (Attachment 3), the ASC signals are coming from ASS and IOO. The ASS path has the filter module (C1:RFM-ETMX_PIT and etc). This FM is quiet and not guilty.

- Why do we have the RFM from IOO? I went to IOO and found the new ASC (WFS) model is there. I didn't realize the presence of this model. In fact ASC screen showed that these random numbers are flowing into the end SUSs.
So I did burtrestore of c1iooepics. Alas! they are gone.

Now I can go home.

Attachment 1: Screenshot_2022-02-10_21-46-02.png
Attachment 2: Screen_Shot_2022-02-10_at_21.54.21.png
Attachment 3: Screen_Shot_2022-02-10_at_22.14.23.png
  16671   Mon Feb 14 21:03:25 2022 KojiUpdateGeneralScheduled power outage recovery

I opened the boxes. Allegra has obvious vent of at least 4 caps. And the power supply did not respond even a paper clip test was performed. https://www.silverstonetek.com/downloads/QA/PSU/PSU-Paper%20Clip-EN.pdf (Paper Clip Test)
=> The mother board and the PSU are dead.

Then Ottavia was also checked. The mother board looked OK, but the PSU did not respond. I quickly opened the PSU and it had a bunch of bulged capacitors in it. => PSU dead

Conclusion: Save the cards/memory etc as much as possible. Migrate the allegra HDD to any other healthy PC or obtain a new used PC from Larry. Otherwise, we just want to buy another WS and copy the disk in it.


Attachment 1: PXL_20220215_025325118.jpg
  16672   Tue Feb 15 19:32:50 2022 KojiUpdateGeneralScheduled power outage recovery - IMC recovery progress

Reduced the IMC power to 100mW

Setup: The power meter was placed right before the final aperture (Attachment 1)

Before the adjustment: Initial position of the HWP was 37.29deg and the input power was 987mW (Attachments 2/3)

After the adjustment: Initial position of the HWP was 74.00deg and the input power was 100mW (Attachments 4/5)

This made the MCREFL reading 0.549.

The MC refl path optics has not been modified.

Attachment 1: PXL_20220216_001731377.jpg
Attachment 2: Screen_Shot_2022-02-15_at_16.18.16.png
Attachment 3: PXL_20220216_001727465.jpg
Attachment 4: Screen_Shot_2022-02-15_at_16.22.16.png
Attachment 5: PXL_20220216_002229572.jpg
  16673   Tue Feb 15 19:40:02 2022 KojiUpdateGeneralIMC locking

IMC is locking now. There was nothing wrong: just a careful alignment + proper gain adj

=== Primary Alignment ===

- I used WFS error signals as the indicator of the PDH error signals. Checked C1:IOO-WFS1_(I/Q)n_ERR and ended up C1:IOO-WFS1_I4_ERR as it showed the largest PDH error PP.

- Then used MC2 and MC3 to align the IMC by maximizing the PDH error and the MC trans (C1:IOO-MC_TRANS_SUM_ERR)

=== Locking procedure ===

Note that the MC REFL path is still configured for the full power input

- (Only at the beginning) Run scripts/MC/mcdown for initialization / Run scripts/MC/MC2tickleOFF just in case

- Enable IOO-MC-SW1 (MC SERVO switch right after "IN1 Gain (dB)").
- Disable 40:4000 boost
- Increase VCO Gain from -15 to 0
- Jiggle IN1 Gain from low to +31 until the lock is achieved

- As soon as the lock is acquired, enable 40:4000
- Increase VCO Gain to +10
- Turn up "SUPER BOOST" from 0 to 3

=== Lock loss procedure ===

Note that the MC REFL path is still configured for the full power input

- Disable IOO-MC-SW1
- Disable 40:4000 boost
- Reduce VCO Gain 0
- Turn down "SUPER BOOST" to 0

- Then jiggle IN1 Gain again to lock the IMC

=== MC2 spot ===

- It was obvious that the MC2F spot was not on the center of the optic.
- I tried to move the spot on the camera as much as possible, but this did not make the trans beam to the center of the MC end QPD
- I had the impression that the trans beam started to be clipped when the beam was moved towards the end QPD,

We need to reestablish the reasonable/consistent MC2 spot on the mirror, the MC end optics, and the QPD.
We will need to use MC2 dithering and A2L coupling to determine the center of the mirror

But as long as the transmission is maximized, the transmitted beam thru MC1 and MC3 follows the input beam. So we can continue the vent work

The current maximized transmission was ~1300. MC1 refl CCD view was largely off -> The camera path was adjusted.

=== MC2 alignment note ===

During the alignment, I noticed a sudden change of the MC2 alignment. There might be some hysteresis in the MC2 suspension. If you are locking the IMC and noticed significant misalignment, the first thing to try is to touch MC2 alignment.

ELOG V3.1.3-