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ID Date Authorup Type Category Subject
  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.

  16684   Sat Feb 26 23:48:14 2022 KojiUpdateSUSETMY SUS Electronics Replacement

[Ian, Koji] - Activity on 25th (Fri)

We continued working on the ETMY electronics replacement.

- The units were fixed on the rack along with the rack plan.

- Unnecessary Eurocard modules were removed from the crate.

- Unnecessary IDC cables and the sat amp were removed from the wiring chain. The side cross-connects became obsolete and they also were removed.

- A 18V DC power strip was attached to one of the side DIN rails.


- Right now the ETMY suspension is free and not damped. We are relying on the EQ stops.

Next things to do:

- Layout the coil driving cables from the vacuum feedthru to the sat amp (2x D2100675-01 30ft ) [40m wiki]

- Layout DB cables between the units

- Layout the DC power cables from the power strip to the units

- Reassign ADC/DAC channels in the iscey model.

- Recover the optic damping

- Measure the change of the PD gains and the actuator gains.

  16685   Sun Feb 27 00:37:00 2022 KojiUpdateGeneralIMC Locking Recovery


- IMC was locked.
- Some alignment change in the output optics.
- The WFS servos working fine now.
- You need to follow the proper alignment procedure to recover the good alignment condition.

- Basically followed the previous procedure 40m/16673.
- The autolocker was turned off. Used MC2 and MC3 for the alignment.
- Once I hit the low order modes, increased the IN1 gain to acquire the lock. This helped me to bring the alignment to TEM00
- Found the MC2 spot was way too off in pitch and yaw.
- Moved MC1/2/3 to bring the MC2 spot around the center of the mirror.
- Found a reasonably good visibility (<90%) at a MC2 spot. Decided this to be the reference (at least for now)

SP Table Alignment Work
- Went to the SP table and aligned the WFS1/2 spots.
- I saw no spot on the camera. Found that the beam for the camera was way too weak and a PO mirror was useless to bring the spot on the CCD.
- So, instead, I decided to catch an AR reflection of the 90% mirror. (See Attachment 1)
- This made the CCD vulnerable to the stronger incident beam to the IMC. Work on the CCD path before increasing the incident power.

MC2 end table alignment work
- I knew that the focusing lens there and the end QPD had inconsistent alignment.
- The true MC2 spot needs to be optimized with A2L (and noise analysis / transmitted beam power analysis / etc)
- So, just aligned the QPD spot using today's beam as the temporary target of the MC alignment. (See Attachment 2)

Resulting CCD image on the quad display (Attachment 3)

WFS Servo
- To activate the WFS with the low transmitted power, the trigger threshold was reduced from 5000 to 500. (See Attachment 4)
- WFS offset was reset with /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_RF_offsets
- Resulting working state looks like Attachment 5

  16686   Sun Feb 27 01:12:46 2022 KojiUpdateGeneralIMC manual alignment procedure

We expect that the MC sus are susceptible to the temperature change and the alignment drifts away with time.

Here is the proper alignment procedure.

0) Assume there is no TEM00 flash or locking, but the IMC is still flashing with higher-order modes.

1) Use the CCD camera and WFS DC spots to bring the beam to the nominal position.

2) Use only MC2 and MC3 to align the cavity to have low-order modes (TEM00,01,02 etc)

3) You should be able to lock the cavity on one of these modes. Minimize the reflection (maximize the transmission) for that mode.

4) This should allow you to jump to a better lower-order mode. Continue alignment optimization only with MC2/3 until you get TEM00.

5) Optimize the TEM00 alignment only with MC2/3

6) Look at the MC end QPD. use one of the scripts in scripts/MC/moveMC2 . Note that the spot moves opposite to the name of the scripts. i.e. MC2_spot_down moves the spot up, MC2_spot_right moved the spot left, etc...
These scripts move MC1/2/3 and try to keep the good MC transmission.

7) moveMC2 scripts are not perfect. As you use them, it makes the MC alignment gradually degraded. Use MC2 and MC3 to recover good transmission.

8) If MC2 spot is satisfactory, you are done.


Step 6-8 can be done with the WFS on. This way, you can skip step 7 as the WFS servo takes care of it. But if the spot move is too fast, the servo can't keep up with the change. If so, you have to wait for the settling of the servo. Once the spot position is satisfactory, MC servo relief should be run so that the servo offset (in actuation) can be offloaded to the bias slider.


  16690   Tue Mar 1 19:26:24 2022 KojiUpdateSUSETMY SUS Electronics Replacement

The replacement key switches and Ne Indicators came in. They were replaced and work fine now.

The power supply units were tested with the X end HeNe display. It turned out that one unit has the supply module for 1350V 4.9mA while the other two do 1700V 4.9mA.
In any case, these two ignited the HeNe Laser (1103P spec 1700V 4.9mA).

The 1350V one is left at the HeNe display and the others were stored in the cabinet together with spare key SWs and Ne lamps.

  16695   Thu Mar 3 04:11:36 2022 KojiUpdateSUSETMY 1Y4 Electronics Replacement

For the Y-end electronics replacement, we want to remove unused power supplies. In fact, we already removed the +/-5V supplies from the stack. I was checking what supply voltages are used by the Eurocard modules. I found that D990399 QPD whitening board had the possible use of +/-5V.

The 40m Y-end version can be found here D1400415. The +/-5V supply voltages are used at the input stage AD620 and the QPD bias voltage of -5V.

AD620 can work with +/-15V. Also the bias voltage can easily be -15V. So I decided to cut the connector legs and connected +5V line to +15V, and -5V line to -15V.

With this modification, I can say that the eurocards only use the +/-15V voltages and nothing else.

The updated schematics can be found as D1400415-v6

  16696   Thu Mar 3 04:24:23 2022 KojiUpdateSUSETMY 1Y4 Electronics Replacement

The DC power strip at Y-end was connected to the bottom two Sorensen power supplies. They are configured to provide +/-18V.


  16701   Fri Mar 4 18:12:44 2022 KojiUpdateVACRGA pumping down

1. Jordan reported that the newly installed Pirani gauge for P2 shows 850Torr while PTP2 show 680 Torr. Because of this, the vacuum interlock fails when we try to open V4.

2. Went to c1vac. Copied the interlock setting file interlock_conditions.yaml to interlock_conditions_220304.yaml
3. Deleted diffpressure line and pump_underspeed line for V4
4. Restarted the interlock service

controls@c1vac:/opt/target/python/interlocks$ sudo systemctl status interlock.service  
controls@c1vac:/opt/target/python/interlocks$ sudo systemctl restart interlock.service
controls@c1vac:/opt/target/python/interlocks$ sudo systemctl status interlock.service

5. The above 2~4 was unnecessary. Start over.

Let RP1/3 pump down TP1 section through the pump spool. Then let TP2 pump down TP1 and RGA.

1. Open V7. This made P2 a bit lower (P2 is alive) and P3.
2. Connected the main RP tube to the RP port.
2. Started RP1/3. PRP quickly reaches 0.4Torr.
3. Opened V6 this made P3 and O2 below 1Torr.
4. Close V6. Shutdown RP1/3. Disconnect the RP tube.
5. Turn on auxRP at the wall powe
6. Turn on TP2. Wait for the starting up.
7. Open V4. Once the pressure is below Pirani range, open VM3.
8. Keep it running over the weekend.

9. Once TP2 reached the nominal speed, the "StandBy" button was clicked to lower the rotation speed (for longer life of TP2)

  16702   Sat Mar 5 01:58:49 2022 KojiSummaryCDSpaola rescue

ETMY end ThinkPad "paola" could not reboot due to "Fan Error". It seems that it is the failure of the CPU fan. I really needed a functional laptop at the end for the electronics work, I decided to open the chassis. By removing the marked screws at the bottom lid, the keyboard was lifted. I found that the CPU fan was stuck because of accumulated dust. Once the fan was cleaned, the laptop starts up as before.

  16703   Sat Mar 5 02:03:46 2022 KojiUpdateSUSETMY 1Y4 Electronics Replacement

Oplev saga


- The new coil driver had not enough alignment range to bring the oplev beam back to the QPD center
- The coil driver output R was reduced from 1.2k to 1.2k//100 = 92.3 +/- 0.4 Ohm
- Now the oplev spot could be moved to the center of the QPD

- The damping gains (POS/PIT/YAW) and the oplev gains were reduced by a factor of 1/10.
- The damping and the oplev servos work now. Fine gain tuning is necessary.

To Do:
- DC value / TF measurements
- Adjust damping gains
- RFM issue
- Connection check
- Cable labeling

== Alignment Range ==

- Since c1auxey was removed, we no longer have C1:SUS-ETMY_PIT_COMM and C1:SUS-ETMY_YAW_COMM. At this moment, all the alignment is taken with the offset input from the fast real-time system via C1:SUS-ETMY_PIT_OFFSET and C1:SUS-ETMY_YAW_OFFSET.

- The oplev spot could not be moved on the center of the QPD without exceeding the DAC output range (~+ or -32000) for the coils. (Attachment 1)

- This is because the old system had a slow but large current range (Rout = 100) and a small current range for the fast control. Until we commission the new HV BIAS Driver, we have to deal with the large DC current with the HAM-A coil driver.

== Modification to the output resistances ==

The following units and the channels were modified. Each channel had a differential current driver and two output resistances of 1.2K. 100Ohm (OHMITE 43F100, 3W) wire wound resistors were added to them in parallel, making the resulting output R of ~92Ohm.

- ETMY HAM A Coil Driver 1: S2100622 (Attachments 2/3) CH1/2/3
- ETMY HAM A Coil Driver 2: S2100621 (Attachments 4/5) CH3

- This modification allowed me to align the oplev spot to the center of the QPD. C1:SUS-ETMY_PIT_OFFSET and C1:SUS-ETMY_YAW_OFFSE are +2725 (8%FS) and -2341 (7%FS), respectively.
- The previous alignment slider values were -0.9392 and 0.7615 (out of 10). These are the reasonable numbers, considering the change of the Rout from 100 to 92Ohm, and the sign flip.
(By the way, autoBurt files for c1auxex and c1auxey were not properly configured and the history of C1:SUS-ETM*_*_COMM was not recorded.)

== Damping Servos ==

- Now, the POS/PIT/YAW servos experience ~x10 gains. So temporarily these gains were reduced (POS 20->2, PIT 6->0.6, YAW 4->0.4) and the loops are stable when engaged.
- Also the gains of the OPLEV servos were reduced from -4.5 to -0.45. The loops are stable when engaged.

== Snapshot of the working condition ==

Attachent 6 shows the screenshot for the snapshot of the working condition.

To Do

- The damping servos were tested without proper PD whitening compensation.
  -> It turned out this is not necessary as our modified PD whitening has the pole and zero at the same freqs as before.

- Compare the DC values of the OSEM outputs and compensate for the gain increase by the "cts2um" filter.

- The end RTS suffers from the RFM issue. There is no data transmitted from the vertex to the end. I suspect we need to restart the c1rfm process. But this will likely suspend all the vertex real-time machines. Careful execution is necessary.

- c1iscey has all the necessary analog connections. But they are not tested. When we lock the green/IR cavity, we'll need them.

- The cable labeling is only half done.

  16707   Mon Mar 7 14:52:34 2022 KojiUpdateVACOngoing work to get the FRG gauges readouts to EPICs channels

Great trouble shoot!

> I guess, the only remaining issue now is the incorrect atmospheric pressure reading of 1000 Torrs. 

This is just a calibration issue. The controller should have the calibration function.
(The other Pirani showing 850Torr was also a calibration issue although I didn't bother to correct it. I think the pirani's typically has large distribution of the calibration values and requires individual calibration)

  16708   Mon Mar 7 14:55:33 2022 KojiUpdateIOOIMC unlocked again, completely misaligned

Hmm, the bias values were reset at 2022-03-03-20:01UTC which is 2022-03-03-12:01 PST with no apparent disruption of the data acquisition (= no resetting of the RTS). Not sure how this could happen.


  16711   Mon Mar 7 18:53:16 2022 KojiUpdateBHDRe-susspension of AS1

Not sure if that small difference can cause the alignment inability. Particularly, the removed metal was just below the wire. This means that there is no misalignment effect at the first order.

Here is my idea:
You may be able to assist the alignment by adding washers on one side of the four holes to this "H" shaped parts. The holes are away from the center line, adding some weight definitely do some misalignment.


  16719   Wed Mar 9 12:57:52 2022 KojiUpdateBHDSimplified BHD readout sketch on ITMY table

- BHD beams were already mixed in the chamber. So we don't need a BS on the table. (Probably there is no BS already)

- We don't need to split each BHD beam. One PD per BHD beam is OK for now.

- Check if the BHD paths have reasonable angles from the windows so that the beams do not hit the chamber wall.

- We need the POY path. POY indeed goes to the BS table

  16752   Fri Apr 1 17:02:02 2022 KojiUpdateOptical LeversSimplified sketch on MC table

We are supposed to have BS Oplev Beams. We don't like the shallow angle reflections (i.e. AOI>45deg).

The laser is too big but I suspect the other components are too small. So it'd be check the actual size of the components including the optical mounts that are missing on the figure so far.

  16753   Fri Apr 1 22:22:29 2022 KojiUpdateOptical LeversSimplified sketch on MC table

Possibility to swap BS and ITMX tables:
BS table, which Tega said MC table, is 2ft x 4ft. The ITMX table is 3ft x 5ft and only the central 2ft x 4ft area is used. The area around the BS table is the narrowest for the east arm. We need at least (2+delta) ft of the hallway width so that we can move the instrument. I'm not yet sure if the ITMX table can be placed there without precise investigation.

  16758   Wed Apr 6 01:20:48 2022 KojiSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

PR2/PR3 Output R for fame OSEMS reduced from 1.2K to 1.2K//100Ohm

I put the R=100Ohm for PR3 with the functions of the units mistakenly swapped. This affects imbalanced actuation of PR3 right now as well as too strong SD

PR2 Coil Driver 1 (UL/LL/UR) / S2100616 / PCB S2100520 / R_OUT = (1.2K // 100) for CH1/2/3

PR2 Coil Driver 2 (LR/SD) / S2100617 / PCB S2100519 / R_OUT = (1.2K // 100) for CH3

PR3 Coil Driver 1 (UL/LL/UR) / S2100619 / PCB S2100516 / R_OUT = (1.2K // 100) for CH3 only

PR3 Coil Driver 2 (LR/SD) / S2100618 / PCB S2100518 / R_OUT = (1.2K // 100) for CH1/2/3


The output R was reduced from 1.2k to 1.2k//100 = 92 Ohm.

This means that the face coil gains were increased by a factor of 13.

The original gains for PR2 Pos/Pit/Yaw were {0.7, 0.3, 0.2}. To keep the same loop gain, the new gains were supposed to be {0.054, 0.023, 0.015}.
With the new gain, the oscillations were very slowly reduced. Therefore, I increased the gains to have the gain margin of 2. (i.e. increased the gains until I have the oscillation, and then made it half.)
The new values were {0.2, 0.1, 0.05}. The side gain was 20 and unchanged

For PR3 the same operation has been done.

The original gains for PR3 Pos/Pit/Yaw were {1, 0.52, 0.2}. They were supposed to be reduced to  {0.077, 0.04, 0.015}.
The gains were increased to {0.5, 0.1, 0.1}. The side gain was also increased from 1 to 5.

  16760   Wed Apr 6 22:51:47 2022 KojiSummaryBHDPart IIa of BHR upgrade - IR laser alignment on Xarm

[Yuta Koji]

We took out the two coil driver units for PR3 and the incorrect arrangement of the output Rs were corrected. The boxes were returned to the rack.

In order to recover the alignment of the PR3 mirror, C1:SUS_PR3_SUSPOS_INMON / C1:SUS_PR3_SUSPIT_INMON / C1:SUS_PR3_SUSYAW_INMON were monitored. The previous values for them were {31150 / -31000 / -12800}. By moving the alignment sliders, the PIT and YAW values were adjusted to be {-31100 / -12700}. while this change made the POS value to be 52340.

The original gains for PR3 Pos/Pit/Yaw were {1, 0.52, 0.2}. They were supposed to be reduced to  {0.077, 0.04, 0.015}.
I ended up having the gains to be {0.15, 0.1, 0.05}. The side gain was also increased to 50.


Overall, the output R configuration for PR2/PR3 are summarized as follows. I'll update the DCC.

PR2 Coil Driver 1 (UL/LL/UR) / S2100616 / PCB S2100520 / R_OUT = (1.2K // 100) for CH1/2/3

PR2 Coil Driver 2 (LR/SD) / S2100617 / PCB S2100519 / R_OUT = (1.2K // 100) for CH3

PR3 Coil Driver 1 (UL/LL/UR) / S2100619 / PCB S2100516 / R_OUT = (1.2K // 100) for CH1/2/3

PR3 Coil Driver 2 (LR/SD) / S2100618 / PCB S2100518 / R_OUT = (1.2K // 100) for CH3

  16771   Mon Apr 11 21:44:14 2022 KojiSummaryBHDPart IIa of BHR upgrade - POY11 debugging

We took out the right most PD interface board D990543 and removed the 74LS04 chips. In fact two out of 4 were already replaced with enabling wires, however it seemed that one of the remaining two got failed.
These remaining two chips were removed and the enabling signals were connected to VCC (+5V). This operation made the status LED light not functional. (We didn't bother to fixed them by connecting them to the GND)

The new schematic diagram was attached here, and the corresponding DCC entry (https://dcc.ligo.org/D1900318-v1) was modified. Attachments #2-3 show the circuit after the changes, and the front view respectively.

  16776   Wed Apr 13 18:55:54 2022 KojiUpdateCamerasCamera Battery Test

I believe that the Nikon has an exposure problem and that's why we bought the Canon.


  16787   Mon Apr 18 23:22:39 2022 KojiUpdateGeneralTool box and Work Station Organization

Whoa! Thanks!

  16791   Wed Apr 20 16:11:08 2022 KojiUpdateSUSOutpur resistors updated for LO1 coil drivers / for SR2, LO2, AS1, and AS4 in progress

[JC Koji]

To give more alignment ranges for the SUS alignment, we started updating the output resistors of the BHD SUS coil drivers.
As Paco has already started working on LO1 alignment, we urgently updated the output Rs for LO1 coil drivers.
LO1 Coil Driver 1 now has R=100 // 1.2k ~ 92Ohm for CH1/2/3, and LO1 Coil Driver 2 has the same mod only for CH3. JC has taken the photos and will upload/update an elog/DCC.

We are still working on the update for the SR2, LO2, AS1, and AS4 coil drivers. They are spread over the workbench right now. Please leave them as they're for a while.
JC is going to continue to work on them tomorrow, and then we'll bring them back to the rack.

  16792   Wed Apr 20 18:50:03 2022 KojiUpdateBHDPart V of BHR upgrade - PR2 weirdness

It seemed that it comes from the servo oscillation. This does not happen when the output limitters were set to be 100-ish. But even so the gains looked quite low.

I turned on the Cheby rool-offs for all the DOFs, and this allowed me to increase the damping gain A LOT.
The gains were 2~5 but now they are now 20-25 for the face OSEMs and 150 for SD.

The attached is the example of the damping when all the damping loops are on.

I think we need to tune the servo loops carefully for all the SUSs by actually looking at the openloop transfer functions rather than a personal feeling. => To Do

  16793   Thu Apr 21 10:35:23 2022 KojiUpdateCDSDAQ seemed down

Yesterday, when I worked on the damping servo, I found that any of the daqvtools (ndscope, dtt, dataviewer,...) is not available.  We may need to restart the fb and rt machines.

  16795   Thu Apr 21 15:22:44 2022 KojiUpdateSUSOutpur resistors updates for SR2, LO2, AS1, and AS4 done

[JC Koji]

Quick report: JC has done all the mods for the coil driver circuit in the morning and we worked on the reinstallation of them in the afternoon.
I'll check the damping loops / sus servo settings. JC is going to make an ELOG entry and DCC updates for more precise record of the mods.

  16801   Thu Apr 21 20:33:31 2022 KojiUpdateBHDAS1 UR OSEM problem localized in the chamber

Tega and Paco reported that the UR OSEM of AS1 lost the response.

- I have checked the LED MON (left) of the satellite amp for AS1. CH1/2/3 had 5V -> This indicates that the OSEM LEDs are (most likely) functioning.
- Then I went to the ITMY flange and connected the OSEM emulator instead of the Dsub25 cable. The attachment shows that the UR OSEM LED/PD worked fine with the OSEM emulator. WIth the vacuum flange connected it lost the response.

This indicates that the AS1 UR OSEM problem is localized in the chamber. Please check if the DSUB pins are touching the table or something else.


  16809   Mon Apr 25 14:49:02 2022 KojiUpdateGeneralNitrogen Tank

For your (and mine) info:

N2 pressure can be monitored on the 40m summary page: https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20220425/vacuum/
(you need to hit "today" to go to the current status)


  16839   Mon May 9 22:19:06 2022 KojiUpdateBHDBHD Platform Progress status

[Don, Koji]

Don is working on finalizing the BHD Platform design. All the components on the BHD platform are almost populated and aligned.

Don is still working on the table legs so that we can detach the legs when we need to float the table in the future.
The BHD BS mount will have a third picomotor so that we can steer 3 dof with the mount while the remaining dof needs to be provided by the OMC.
The BHD BS position is going to be adjusted so that the incident and trans beams have sufficient clearance.
The OMC legs (kinematic mounts) need more work so that we can adjust their positions for initial setup while they can be the reference for the reproducible placement of the OMCs.
The OMCs are rigidly held with the legs. For the damping of the 1-kHz body bode, which has a relatively high Q, there will be a dissipative element touching the glass breadboard.

  16840   Mon May 9 23:18:44 2022 KojiUpdateBHDBHD Platform Progress status

I quickly ran the FEA model to check the resonant freqs of the BHD platform.
The boundary conditions were:

  • The platform was not loaded
  • FIxed constraints were given to the five legs

Don has optimized the cut-out size for the OMCs to increase the rigidity of the plate. Also, the ribbed grid is made at the bottom side.

The lowest mode is at 168Hz. Because there is no leg around, it seems reasonable to have this kind of mode as the fundamental mode.
The other mode lined up at 291Hz, 394Hz, 402Hz, ...
The mode freqs will be lower once the platform is loaded. But as the unloaded platform mode, these mode freqs sound pretty good numbers.

  16895   Mon Jun 6 22:08:55 2022 KojiUpdateIMCMC1 OSEM sensor sign flipped, MC1/2/3 free swinging overnight for inmat diagonalization

Note that MC1 has a new style sat amp because the old one collapsed. The sign flip might have been the result of the replacement


  16900   Wed Jun 8 16:03:12 2022 KojiUpdateVACPower Outage 220608: Vacuum Recovery

=== Observation ===

  • TP1/2/3 failed. AUX RP did not survive the power outage (of course)

=== Initial Recovery of TP2/TP3 ===

  • Stopped TP1/2/3
  • Restored RP AUX at the wall breaker module
  • Restarted TP2/3

=== Rough pumping down ===

  • Found RP1/RP3 left connected (unusual)
  • Turned on RP1 and RP3
  • Opened V6 and V7 for roughing of the pump spool. Now 0.3 torr for P2/P3/PA* (annuli) - ready to open V4 and V5 to backup TP1 by TP2 and TP3. Waiting for TP2/3 to be accelerated

=== Towards main volume pumping ===

  • TP2 accelerated and opened V4 (This caused V6 to close). RP1 and RP3 stopped.
  • TP3 hasitated to spin up. Stopped for now.
  • TP1 needed to be reset to clear the displacement errors. Once the errors were cleared, TP1 was restarted (acclerating).
  • TP1 at normal speed. Opened V1 (main volume pumping started)
  • Disconnected RP1/RP3 line.
  • TP3 was restarted and is now stable at 55k RPM (indicated as soft spin / low speed). Pushed "Stand By On" and "then "Stand By OFF". This makes the TP3 back to "NORMAL". Switched to "Stand By On".
  • TP2 was also switched to "Stand By On".

Now the main volume and the annuli are pumped down TP1 and TP2/TP3 with RP AUX backing.

The attachment is the pressure glitch for the main volume.


  16901   Wed Jun 8 16:33:26 2022 KojiUpdateGeneralPower Outage 220608: HVAC restored

I found the HVACs for the ends were off. They were turned back on.

  16902   Wed Jun 8 16:57:46 2022 KojiUpdateIOOPower Outage 220608: IMC restored

The IMC alignment was restored and the IMC is nicely locking.

Once the vacuum level recovered P<1e-4 torr, the PSL shutter was able to be opened.

The IMC was still flashing, so the lock to TEM00 was possible.

Once it was locked, the MC2 alignment was tweaked and the autolocker and the WFS kicked in to help the locking/alignment.

The transmission is ~13k and seems reasonable considering the low PMC transmission of the PMC (0.672)

  16917   Wed Jun 15 15:03:41 2022 KojiUpdatePSLPMC input beam aligned

The commissioners complained about the PMC alignment. The PMC input beam was aligned. It made the transmission improved from 0.72 to 0.74.

FYI: Which steering mirrors do we use for the PMC beam alignment?
The mounts are indicated with the red arrows in Attachment 2.
You have to move these two in common and differential for each pitch and yaw.
The first steering (the right one in the picture) has the beam going through the immediate back of the mount.
So touching the yaw knob of this mount needs some care so that you don't block the PMC refl beam.

  16918   Wed Jun 15 15:07:07 2022 KojiUpdateSUSLO2 SUS stuck fixed

I checked the state of the LO2 suspension. I found that the coil driver Enable Mon was all red. Meaning, the actuation signals were not delivered to the coil driver. I wasn't sure if this was intentional or not.

Enabled the coils with "WD Master" Shutdown -> Normal.

Immediately I saw the OSEMS flipped the sign because there was an (non-intentional) alignment offset in pitch. I've adjusted the pitch offset so that all the OSEM PDs have the voltages 4~5V.

That's it.

  16928   Fri Jun 17 13:07:08 2022 KojiUpdateBHDComparison of MICH OLTF model with measurement

I'm curious why the actual OLTF included the 60Hz comb...? It is undesirable to have such structure in the OLTF around the UGF as it can cause servo instability.
And if you remove them, you don't need to model them :-)

  16941   Wed Jun 22 19:41:13 2022 KojiUpdateLSCDaily alignment work; POY trouble solved

Before the final measurement of the DC values for the transmissions, I aligned the PMC. This made the PMC trans increased from 0.67 to 0.74.

  16947   Sat Jun 25 20:23:59 2022 KojiUpdateIOOWFS issues

I could run the WFS servo (6dofs) for more than 15min by flipping the sign for the MC2 Pit and WFS1 Yaw. (See attachments)

This may mean that the sign of the loops / the input matrix / the output matrix, as well as the sensors and actuators, have the problem.
Isn't it the time to measure the sensing/actuation matrices? Maybe Tomislav already has the data?

I have reverted the changes as you may need more careful investigation.

  16969   Fri Jul 1 12:49:52 2022 KojiUpdateIOOMC2 seemed misaligned / fixed

I found the IMC was largely misaligned and was not locking. The WFS feedback signals were saturated and MC2 was still largely misaligned in yaw after resetting the saturation.
It seemed that the MC WFS started to put the large offset at 6:30AM~7:00AM (local).
MC2 was aligned and the lock was recovered then the MC WFS seems working for ~10min now.

  16982   Fri Jul 8 23:10:04 2022 KojiSummaryGeneralJuly 9th, 2022 Power Outage Prep

The 40m team worked on the power outage preparation. The detailed is summarized on this wiki page. We will still be able to access the wiki page during the power outage as it is hosted some where in Downs.


  16987   Mon Jul 11 17:41:52 2022 KojiHowToVACStartup after Power Outage

- Once the FRG gauge readings are back (see next elog by Tega), I could open V1 to pump down the main vacuum manifold.
- TP2/TP3 were brought back to stand-by mode (slower spinning)
- V7 was closed to separate the annuli side and TP1

During the vacuum recovery, I saw TPs were automatically turned on as soon as the backing pumps were engaged. I could not figure out what caused this automation.

Also, I saw some gate valve states changed while I was not touching them. e.g. V7 was close / VM3 was open / etc
I really had no idea what/who was handling these.

As of ~18:00 local, the main volume pressure is ~2e-5 torr and ready to open the PSL shutter.

  17000   Wed Jul 13 17:30:19 2022 KojiUpdateCDSToo huge script_archive

I wanted to check the script archive to see some old settings. I found that the script archive inflated to huge volume (~1TB).
The size of the common NFS volume (/cvs/cds) is 3TB. So it is really significant.

- The scripts living in /opt/rtcds/caltech/c1/scripts are archived daily in /cvs/cds/caltech/scripts_archive as bz2 files. This is done by crontab of megatron (see https://wiki-40m.ligo.caltech.edu/Computers_and_Scripts/CRON)

- In fact, the script folder (say old script folder) /opt/rtcds/caltech/c1/scripts has the size of 10GB. And we have the compressed copy of thi s everyday.

- This large script folder is due to a couple of huge files/folders listed below

  • (scripts)/MEDMtab is 5.3GB / This is probably related to the web MEDM view (on nodus) but I don't think the web page is not updated. (i.e. the images are unused)
  • (scripts)/MC/logs/AutoLocker.log 2.9GB / This is just the accumulated MC autolocker log.
  • (scripts)/GigE 780M / This does not look like scripts but source and object files
  • (scripts)/Admin/n2Check.log 224M / This is important but increases every minute.
  • (scripts)/ZI 316MB / Zurich Instrument installation. This should not be here.

Here I propose some changes.
For the script archive

  • We can remove most of the scripts for the past (say ~2019). We leave an archive file per month.
  • For the scripts in 2020, we leave a weekly archive.
  • For 2021 and 2022, we leave all the archive files.

For the existing large files/folders

  • MEDMtab: the stored files are redundant with the burt snapshots. Remove the image files. Also, we want to move the image-saving location.
  • Autolocker.log: simply zap it
  • n2Check.log: we should move the saving location
  • GigE /ZI: they need a new home where the daily copy is not taken.
  17001   Wed Jul 13 18:58:17 2022 KojiUpdateIOOIMC suspecion

This is just my intuition but the IMC servo seems not so optimized. I can increase the servo gain by 6~10dB easily. And I couldn't see that the PC drive went mad (red) as I increase the gain (=UGF).
The IMC needs careful OLTF measurements as well as the high freq spectrum observation.

It seems that I have worked on the IMC servo tuning in 2014 July/Aug. Checking these elogs would be helpful.

  17009   Sat Jul 16 02:44:10 2022 KojiUpdateIOOIMC servo tuning

I wasn't sure how the IMC servo was optimized recently. We used to have the FSS over all gain (C1:PSL-FSS_MGAIN) of +6dB a few years back. It is not 0dB. So I decided to do a couple of measurements.

1) Default setting:


2) Looked at the power spectrum at TEST1A output (error signal)
TEST1A is the signal right after the input gain stage (C1:IOO-MC_REFL_GAIN). Prior to the measurement, I've confirmed that the UGF is ~100Hz even at +0dB (see next section). It was not too bad even with the current default. Just wanted to check if we can increase the gain a bit more.
The input gain was fixed at +4dB and the FSS overall gain C1:PSL-FSS_MGAIN was swept from +0 to +6.
At +5dB and +6dB, the servo bump was very much visible (Attachment 1).
I decided to set the default to be +4dB (Attachment 3).

3) Took OLTF at 0dB and 4dB for the FSS overall gain.

Now the comparison of the opel loop transfer functions (OLTF) for C1:PSL-FSS_MGAIN at 0dB and 4dB. The OLTF were taken by injectiong the network analyzer signal into EXCA and measure the ratio between TEST1A and TEST1B (A/B).

C1:PSL-FSS_MGAIN +0 -> UGF 100kHz / Phase Margin ~50deg
C1:PSL-FSS_MGAIN +4 -> UGF 200kHz / Phase Margin 25~30deg

The phase margin was a bit less but it was acceptable.


Took the opportunity to check the FSR of the IMC. Connected a cable to the RF MON of the IMC REFL demod board. Looked at the peak at 40.56MHz (29.5MHz + 11.066MHz). The peak was not so clear at 11.066195MHz (see 40m ELOG 15845). The peak was anyway minimized and the new modulation frequency was set to be 11.066081MHz (new FSR). The change is 10ppm level and it is within the range of the temp drift.

  17015   Mon Jul 18 18:33:38 2022 KojiUpdateBHDadd Laser RIN to MICH budget

You should measure the coupling by noise injection. Noise budgeting does not need any modeling:

1) Measure the power spectrum density of the target signal (i.e. DARM) and the source noise (i.e. RIN this case)

2) Calibrate both using a calibration peak to convert 1) into the physical units (m/rtHz, 1/rtHz, etc)

3) Measure the transfer function from source to target using the noise injection. (i.e. RIN injection this case and look at the injection to RIN and injection to DARM)

4) Measure open-loop transfer functions if necessary. (i.e. DARM control open-loop transfer function to convert the error signal into the free running noise level)

Primarily, these are measured noise levels and noise couplings there is no room to involve a model there.
Once the noise budget was done, you can compare it with the model and say "the coupling is big/small/comparable".

Also, why don't you use C1:MC_TRANS_SUMFILT_IN1_DQ instead? Your _OUT signal seems affected by the bunch of comb notch filters to artificially remove the 60Hz harmonics. It's not a fair RIN measurement.

  17023   Wed Jul 20 15:58:52 2022 KojiSummaryGeneralJenne laser kaput!

For troubleshooting, the proper laser driver (found beneath the AG network analyzer) was connected.
The current ~1mA was provided and the driver detected the "open circuit", which means the laser diode was busted.


The laser diode in the parts list is: "GTRAN GaAs Strained QW Laser Diode, Part # LD-1060".

  17027   Fri Jul 22 17:43:19 2022 KojiUpdateGeneralObtained a functional CRT

[Koji Paco]

Koji went to Downs and found a CRT labeled "for 40m Rana?". So I decided to salvage it to the 40m after getting approval from Rich/Todd.

Paco and I tried this unit with the control room CCD signal and it just worked fine. So we can use this as a spare for any purpose in the lab.

  17038   Tue Jul 26 21:16:41 2022 KojiUpdateComputer Scripts / ProgramsVector fitting

I think the fit fails as the measurement quality is not good enough.


  17043   Thu Jul 28 15:11:59 2022 KojiUpdateCDSToo huge script_archive

As a result of the following work, the file volume of /cvs/cds was reduced from 3.2TB to 2.2TB, and /opt/rtcds/caltech/c1/scripts was reduced from 10GB to 1.5GB

/cvs/cds/caltech/scripts_archive was cleaned up. Now the archive files are reduced to have:

  • every month 1st day from 2005 to 2018/12
  • every ten days (1, 11, 21) for 2019 and 2020
  • everyday for 2021 and 2022

(scripts)/MEDMtab/image was deleted. I can be restore back from one of the script_archive files.

(scripts)/MC/logs/AutoLocker.log was just deleted and refreshed. For the past settings, we can refer autoburt snapshots or script_archive files.


  • It turned out that the frequency of the check was reduced to once per 10min on Sep 9th, 2021 (unelogged activity).
  • The volume of the text since then was not much volume. So I deleted the lines before this date. And the file size is <7MB now.

(scripts)/ZI was moved to /cvs/cds/apps


  • 2018, 2019, 2020 snapshots were archived in tar.gz.
  • These snapshots were then deleted


  17047   Fri Jul 29 20:21:11 2022 KojiUpdatePSLFSSSlow/MCAutolocker issue (docker)

MCAutolocker/FSSSlow are not properly documented and not properly working.
Tidy up the script and documentation, or bring it back to megatron

I was aware that the FSSSlow was misbehaving since the shutdown upon the July power outage.
- FSS Slow servo did nothing even though the apparent settings in C1:PSL_SLOW screen looked fine and heart beat blinking
- Wanted to restart FSSSlow at megatron. Despite the login message showing how to do it, the system service does not exist anymore, because it was moved somewhere.
- Searched 40m wiki but found no info how to kill and restart it
- Found an elog. It was moved to docker on optimus ELOG 16480 . The restart procedure can only be found here. Please fix all the documentation inconsistency >> Anchal

According to this elog, the following commands need to be run for starting up MCAutolocker and FSSSlow on optimus:

cd /opt/rtcds/caltech/c1/Git/40m/scripts/MC
sudo docker-compose up -d

- Problem continues. Now FSSSlow is running but only when the IMC is locked. It does not stop even when the IMC lock is lost. How can we debug docker thing?
- This is minor but the MCAutolocker log (/opt/rtcds/caltech/c1/scripts/MC/logs/AutoLocker.log) is no longer updated even though MCAutolocker is running. Was it moved somewhere?


ELOG V3.1.3-