but what about including the DC reflectivity imbalance of the arms? there would be another BH55 term from that field maybe.

I repeated the calculations but with FPMI (last case was all MICH). The qualitative behavior is the same, the BH55 sensing is mostly affected by residual darm offset. If the darm offset is of a couple of nm, the single RF sideband may sense the LO phase at as much as > 20 deg away from the nominal phase angle. This is not too different from the MICH case; so maybe I overlooked something about how I define FPMI in the calculation.

Attachments #1-3 show the plots of the BH55 (single RF sideband) and BH44 (double RF sideband) sensitivity to LO phase fluctuations around various nominal LO phase angles. Attachment #1 looks at the effect of differential loss, Attachment #2 looks at the effect of differential dc reflectivity (of the ITMs), and Attachment #3 looks at the effect of residual darm offsets. Dashed lines show the orthogonal quadrature (I) of the demodulated RF signals (always minimized).

Here are our best estimates for the optic transmission (power) coefficients.

Assuming our input power to the IFO is 0.95 Watts, and the IMC transmission is 90%, about 855 mW should be incident on the PRM. Furthermore, following our recent estimates we can estimate our PRMI gain to be ~ 13.4.

• Using these numbers we expect a single pass AS power of 517.8 uW and LO power of 530.1 uW when the PRM is misaligned and MICH is free swinging, consistent with recent estimates. When the PRM is aligned we would then expect the max PRMI BHD single port flash to be 7.6 mW.
• Similarly, using these numbers we expect a single pass POPDC power of 1.01 mW, which then is expected to flash at a ~ 13.5 mW level when the PRM is aligned. The POP beam is split between the position sensor, our broadband POP22 and POP110 RFPD, and a CCD camera to monitor the POP beam.

POPDC calibration

I misaligned the PRM and ITMX to get a single ITMY bounce configuration. From the numbers above, I should expect a single ITMY bounce POPDC power of 255 uW. Instead, I measure a total of 173.5 uW = 78 uW (POP QPD) + 91 uW (POP RFPD) + 4.5 uW (POP camera) which is 50% less than expected .  The C1:LSC-POPDC_OUT level for this measurement was 335 counts, giving a rough empirical calibration of 1.931e6 counts / W. When the PRM is aligned and the MICH is free swinging, the POPDC flashes reach levels in excess of 14,500 counts implying 7.51 mW PRMI POPDC power. When PRM is misaligned the POP MICH flashes reach 1360 counts, implying 703 uW (which falls short by ~ 50% from our expectation).

There is probably an unaccounted BS in the ITMX table that may explain our observed difference. Nevertheless, our POPDC calibration should be good from here on.

[Paco, Radhika]

We locked PRMI in carrier.

We refereced the old IFOconfigure script (/opt/rtcds/caltech/c1/burt/c1ifoconfigure/C1configurePRM_Carr.sh) to manually configure the LSC screen for PRMI. The final MICH/PRCL gain values used to achieve lock were flipped in sign:

(.snap file ---> final value)

The FM trigger levels (enable/disable) for PRCL and MICH were set to (150/50). The following filter modules were engaged:

During PRMI lock, the POPDC level reached 13130 counts, or 6.8 mW (using calibration of 1.931e6 counts/W). The POPDC counts level was ~1330 with only MICH locked, meaning the PRC gain was ~10. Attachment 1 is an image of REFL, AS, and POP monitors during lock.

Lock was maintained for close to a minute, allowing us to estimate the UGF at around 100 Hz. We used the AA_PRCL_UGF_meas.xml template to measure the loop transfer function. The GPS time (start, end) for a lock stretch with boost on is (1680547905, 1680547933 1364583160, 1364583442).

Next steps

1. Achieve better angular alignment to keep MICH locked to dark fringe - ASS? Seismic FF?

<p>I purchased some more of these from DigiKey. These parts are currently in the EE shop. These are replacements for the NDP5565 part of the SR560.</p>

I ran two recently trained neural network controllers today between 10 am and Noon. Each test comprised of four segments:

• All loops open
• Linear loop closed
• Neural Network working alone
• Neural Network + Linear Loop

The latest controller unfortunately failed in both cases, working alone and working together with linear loop.

The second latest controller functioned well, keeping the arm locked throughout.

[Paco, Radhika]

We calibrated the PRM oplev.

We took calibrated spectra of oplev PIT and YAW (Attachment 1) with the oplev loops open and closed. We see noise suppression up until a few Hz, as expected. The high-frequency floor appears to be at 1e-9 rad/rtHz with this calibration.

Next steps: improving PRMI angular control

I've turned on NN controller for MC WFS PIT loops. One can disable this controller and go back to linear controller by sitemap>IOO>C1IOO_WFS_MASTER>Actions!>Stop Shimmer . One can start the controller again sitemap>IOO>C1IOO_WFS_MASTER>Actions!>Run Shimmer .

I'm going to get into the PSL enclosure. Also turn on the HEPA for a while during the intrusion.
Work done.

Start of the work:
(cds) ~>gpstime 
PDT: 2023-04-06 21:09:36.670623 PDT
UTC: 2023-04-07 04:09:36.670623 UTC
GPS: 1364875794.670623

End of the work:
(cds) ~>gpstime 
PDT: 2023-04-06 21:19:37.331716 PDT
UTC: 2023-04-07 04:19:37.331716 UTC
GPS: 1364876395.331716

[Paco, Radhika]

To determine the PRM angle-to-length coupling for PRCL, we want to inject pitch/yaw lines into PRM and find the corresponding peaks in the PRCL closed-loop control signal (below loop UGF). Below is a summary of PRMI locking efforts.

Locking PRMI carrier

- Locked arm cavities, ran YARM, XARM ASS to get PR2/PR3 alignment

- Locked MICH to dark fringe

- Aligned PRM by maximizing drop in REFLDC (reaches 2 when well aligned)

         *This was the hurdle when attempting to lock PRMI last week*

- Locked PRMI carrier using configurations in PRMI-AS55_REFL11.yml. There is now a "Lock PRMI (carr) using AS55/REFL11" action on the LSC screen that runs operateLSC.py with the aforementioned yaml file.

- Final DoF gains used: MICH --> 0.8; PRCL --> -0.07. At times BS was being kicked too hard, so we reduced the MICH gain from 1.2.

Lock stability

During PRMI lock, REFLDC was noisy with ~1 Hz fluctuations. We got PRMI to stay locked for a couple minutes at a time. Additionally it couldn't lock the AS port to dark fringe, and it stayed bright while tweaking the BS alignment.

We took spectra of ASDC during a lock stretch to quantify the DC power fluctuations at the AS port [Attachment 1]. The red trace is ASDC with PRMI locked. REF0 (black) is ASDC with MICH locked; REF1/REF2 (blue/green) are ASDC with single-bounce PRCL locked (either ITMX or ITMY misaligned). Note that the PRMI spectrum might need to be normalized by the PRCL gain / PRM transmission: ~ 10/0.057 = 175. The factor difference in ASDC fluctuations between MICH and PRMI for a single test point is ~144 --> with PRMI normalized, the ASDC fluctionations are comparable with MICH.

[Yuta, Radhika]

We copied the coil balancing procedure found in /scripts/SUS/coilStrengthBalancing/AS1/CoilStrengthBalancing.ipynb to a new PRM directory. After modifying channel names for PRM, we followed the coil balancing procedure:

1. Locked PRY. This was chosen since full PRCL lock was not maintainable for the duration of measurement.

2. Injected 13 Hz line into the butterfly mode and looked for a peak in the LSC PRCL control signal (C1:LSC-PRCL_OUT_DQ). It appeared like the existing coil gains for PRM are already tuned to minimize the but-pos coupling.

3. Injected 13 Hz line into the POS mode and looked for a peak in the PRM oplev pitch and yaw signals (C1:SUS-PRM_OL_PIT_IN1_DQ / C1:SUS-PRM_OL_YAW_IN1_DQ). Like above, the existing coil gains seemed to be tuned to minimize the pos-angle coupling.

The attached spectrum was taken when POS was excited at 13 Hz using LOCKIN1. As expected the PRCL control signal sees the actuation, but we do not see a 13 Hz peak in the oplev pitch/yaw signals.

[Paco, Yuta]

We measured the power around BHD PDs to see if the numbers make sense.
Measured values are 10-20% less than expected values, which sounds good.
BHD DC PDs require slight reduction of gains to avoid saturation.

What we measured and result:
 - We measured the power with a Newport power meter (Model 840) for BHD A and B right after the viewport (A path and B path), in front of BHDC A and B, and in front of BH44 and BH55.
 - Note that BH44 is a pick-off from A path and BH55 is a pick-off from B path (see Attachment #1). A path also has a pick-off to BHD camera. So the measured numbers roughly sum up.
 - Measurement was done with LO beam only (misaligned AS4) and PRM misaligned, and PRMI carrier locked (forgot to misalign AS beam, but the most of the power is from LO beam).
 - Results are the following.

        LO beam only        PRMI carrier locked
        (PRM misalgined)    
A path  450 +/- 10 uW       110 +/- 10  mW
B path  360 +/- 10 uW       91 +/- 5 mW
BHDC A  330 +/- 10 uW       74 +/- 1 mW
BHDC B  320 +/- 10 uW       74 +/- 4 mW
BH44    100 +/- 3 uW        27 +/- 2 mW
BH55    3 +/- 1 uW          10 +/- 2 mW

                    LO beam only        PRMI carrier locked
                    (PRM misalgined)
C1:HPC-BHDC_A_OUT16 104                 saturated at ~22000
C1:HPC-BHDC_B_OUT16 103                 saturated at ~22000

Consistency check with previous measurement:
 - Power with LO beam only was measured in July 2022 (elog 40m/17046).
 - Compared with values in July 2022, it is now 10-20% less. This could be explainable by PMC transmission power drop on Dec 27, 2022 by ~10% (elog 40m/17390).

Expected values:
 - Expected values using PSL output of 890 mW (measured in elog 40m/17390) and calculated PRG of 13.4 (elog 40m/17532) are the following (see, also elog 40m/17040). Note that BHD BS has the transmission of 44% and the reflectivity is 56%.

A path, LO beam only
 890 mW * 0.9 (IMC transmission?) * 5.637%(PRM) * 2.2%(PR2) * 56%(BHDBS) = 560 uW
B path, LO beam only
 890 mW * 0.9 (IMC transmission?) * 5.637%(PRM) * 2.2%(PR2) * 44%(BHDBS) = 440 uW
A path, PRMI carrier locked
 890 mW * 0.9 (IMC transmission?) * 13.4(PRG) * 2.2%(PR2) * 56%(BHDBS) = 130 mW
B path, PRMI carrier locked
 890 mW * 0.9 (IMC transmission?) * 13.4(PRG) * 2.2%(PR2) * 44%(BHDBS) = 100 mW

  - Measured values are 10-20% less than expected values.

BHDC PD saturation:
 - Expected counts for C1:HPC-BHDC_A_OUT16 when PRMI carrier locked using LO beam only numbers are

 104 / 5.637% * 13.4 = ~25000

 - So, we are barely saturating.

Next:
 - Measure PRG using POPDC.
 - Reduce transimpedance gain of BHDC A and B by small amount to avoid saturation.

Anchal and I turned on another RL policy (ninedwarfs) with Chris's help.

It looks to be performing great, with good low frequency suppression and low noise injection at higher frequencies.

Going to leave it on overnight. It seems to respond well to lockloss of IMC, me whacking the MC2 chamber, walking near the MC2 chamber, kicking the optics by step in actuators, and turning off the sensors for a few seconds. Pretty robust!

[Mayank, Paco, Yohanathan, Yuta]

We checked if coil dewhitening switch is working by measuring transfer function from coil outputs to oplev pitch and yaw.

Method:
 - Turned off oplev damping loops (this actually changed the result, this means that oplev loops have quite high UGFs)
 - Measured transfer functions from C1:SUS-PRM_(UL,UR,LR,LL)COIL_EXC to C1:SUS-PRM_OL_(PIT|YAW)_OUT, with SimDW and InvDW filters on/off.
 - Injected excitations are about 30000 at 100 Hz and 3000 at 10 Hz.
 - When SimDW and InvDW filters are on, analog dewhitening filter should be off, so it should give suspension mechanical response and other filter shapes in coil driver.
 - When SimDW and InvDW filters are off, analog dewhitening filter should be on, so it should give the same transfer function with analong dewhitening filter.
 - Taking the ratio between two should give analog dewhitening filter shape, which is zero at [70.7+i*70.7,70.7-i*70.7] Hz and pole at [10.61+i*10.61,10.61-i*10.61] Hz, from SimDW filter.

Notebook: /opt/rtcds/caltech/c1/Git/40m/measurements/SUS/PRM/CoilDewhitening/PRMCoilDewhiteningCheck_COIL2OL.ipynb

Result:
 - Attachment #1 shows the result for each coil. 4th panel is the ratio, which should match with analog dewhitening filter shape.
 - The result looks consistent with our expected analog dewhitening filter shape.

Next:
 - Repeat this measurement for other suspensions.
 - PRM suspension response have residual frequency dependence from 1/f^2. What is this?

[Yehonathan, Paco]

Repeated the coil dewhitening check for BS. Attachment #1 show results. Note however the DW filter shape for BS is more complicated:

Note that YAW data here is actually PIT data and PIT data is plotted twice, as we messed up with data saving...

 

Repeated also for ITMX. See Attachment #2.

Yuta and I had a discussion last week about the signal strength between the configurations. Here are some naive calculations.
=== Please check the result with a more precise simulation ===

Michelson: Homodyne (HD) phase signal @44MHz is obtained from the combination of LO11xAS55 and LO CAxAS44. SBs at AS rely on the Schnupp asymmetry, the signal is weaker than the one with a single bounce beam from an ITM.

PRMI Carrier resonant:
- Despite the non-resonant condition of the sidebands, the HD phase signal @44MHz is expected to be significantly stronger (~x300) compared with the MI due to the resonance of the carrier and the 44MHz sidebands (the 2nd-order SBs of 11 and 55) in the PRC. Thus, the LO CAxAS44 term dominates the signal.
- The MICH signal @55MHz is enhanced by the resonant carrier by a factor of ~5.5, in spite of the non-resonant 55MHz SBs.
- The MICH signal @BHD is enhanced by the resonant carrier by a factor of ~300. This is the comparable phase sensitivity to PRFPMI case.

PRMI Sideband resonant:
- Despite the non-resonant condition of the carrier, the HD phase signal @44MHz is expected to be even stronger (~x400) compared with the MI due to the resonance of the 11MHz and 55MHz sidebands in the PRC. Thus, the LO11xAS55 term dominates the signal.
- The level of the MICH signal @55MHz is expected to be comparable to the one with PRMI carrier resonant as the resonant condition for the CA and 55MHz SBs are interchanged.
- The MICH signal @BHD is expected to be negligibly small due to non-resonance of the carrier.

PRFPMI: Now the carrier and the 11 and 55MHz sidebands are resonant.
- The HD phase signal @44MHz is expected to be the same level as the SB resonant PRMI, and the LO11xAS55 term dominates the signal.
- The level of the MICH sensitivity @AS 55MHz shows x300 of the MICH signal of the MI and x50 of the MICH with PRMI.
- The MICH signal @BHD is going to be the same level as the one with PRMI Carrier resonant.
- The DARM signal shows up at the dark port signal enhanced by x300 from the MICH level due to the finesse of the arms.

Simple assumptions
1) PRM has a transmission of T_PRM = 0.05
2) PRG is limited by the transmission of PR2 (T_PR2=0.02 per bounce).
    If the IFO is lossless, PRG is 25 (i.e. theoretical maximum). In reality, the IFO loss is 2~3% -> PRG is ~15.
    The asymmetry of 30mm has a negligible effect.
3) For the anti-resonant fields, APRG is ~T_PRM/4 = 0.0125
4) Arm finesse is 450. Therefore the phase enhancement factor N is ~300.
5) Modulation depth is ~0.1. J0=1, J1=0.05, J2=0.00125
6) Sideband leakage by the asymmetry is ɑ=l_asym wm / c = 0.008 for 11MHz and 5ɑ for 55MHz.

Single Bounce

The numbers are power transmission to each port
   Carrier              11MHz                    55MHz
LO TPRM TPR2 = 1.0e-3   J1^2 TPRM TPR2 = 2.5e-6  J1^2 TPRM TPR2 = 2.5e-6
AS TPRM/4    = 1.3e-2   J1^2 TPRM/4    = 3.1e-5  J1^2 TPRM/4    = 3.1e-5

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-6 * 3.1e-5) = 8.8e-6

Michelson

   Carrier               11MHz                     55MHz                      44MHz
LO TPRM TPR2 = 1.0e-3    J1^2 TPRM TPR2 = 2.5e-6   J1^2 TPRM TPR2   = 2.5e-6
AS TPRM ε^2  = 0.05 ε^2  ɑ^2 J1^2 TPRM  = 8.0e-9   25 ɑ^2 J1^2 TPRM = 2.0e-7  16 ɑ^2 J1^4 TPRM = 3.2e-10

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-6 * 2.0e-7)  = 7.1e-7
                 LO CA x AS 44 = Sqrt(1.0e-3 * 3.2e-10) = 5.7e-7

AS MICH  @55MHz: AS CA x AS 55 = Sqrt(0.05 * 2.0e-7) ε  = 1.0e-4 ε
AS MICH  @BHD:　 LO CA x AS CA = Sqrt(1.0e-3 * 0.05) ε  = 7.1e-3 ε

PRMI (Carrier Resonant)

   Carrier              11MHz                     55MHz                      44MHz
LO PRG TPR2 = 0.3       J1^2 APRG TPR2 = 2.5e-7   J1^2 APRG TPR2   = 2.5e-7  J1^4 PRG TPR2 = 1.9e-6
AS PRG ε^2  = 15 ε^2    ɑ^2 J1^2 APRG  = 8.0e-10  25 ɑ^2 J1^2 APRG = 2.0e-8  16 ɑ^2 J1^4 PRG = 9.6e-8

LO phase @44MHz: LO 11 x AS 55 = Sqrt(2.5e-7 * 2.0e-8)  = 7.1e-8
                 LO CA x AS 44 = Sqrt(0.3 * 9.6e-8)     = 1.7e-4
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(15 * 2.0e-8) ε    = 5.5e-4 ε
AS MICH  @BHD:　 LO CA x AS CA = Sqrt(0.3 * 15) ε       = 2.1 ε
 

PRMI (Sideband Resonant)

   Carrier               11MHz                     55MHz                      44MHz
LO APRG TPR2 = 1e-4      J1^2 PRG TPR2 = 7.5e-4    J1^2 PRG TPR2   = 7.5e-4  J1^4 APRG TPR2 = 6.3e-10
AS APRG ε^2  = 5e-3 ε^2  ɑ^2 J1^2 PRG  = 2.4e-6    25 ɑ^2 J1^2 PRG = 6.0e-5  16 ɑ^2 J1^4 APRG = 3.2e-11

LO phase @44MHz: LO 11 x AS 55 = Sqrt(7.5e-4 * 6.0e-5)  = 2.1e-4
                 LO CA x AS 44 = Sqrt(1e-4 * 3.2e-11)   = 5.7e-8
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(5e-3 * 6.0e-5) ε  = 5.5e-4 ε
AS MICH  @BHD:　 LO CA x AS CA = Sqrt(1e-4 * 5e-3) ε    = 7.1e-4 ε

PRFPMI

   Carrier             11MHz                     55MHz                      44MHz
LO PRG TPR2 = 0.3      J1^2 PRG TPR2 = 7.5e-4    J1^2 PRG TPR2   = 7.5e-4   J1^4 APRG TPR2 = 6.3e-10
AS PRG ε^2  = 15 ε^2   ɑ^2 J1^2 PRG  = 2.4e-6    25 ɑ^2 J1^2 PRG = 6.0e-5   16 ɑ^2 J1^4 APRG = 3.2e-11

LO phase @44MHz: LO 11 x AS 55 = Sqrt(7.5e-4 * 6.0e-5)  = 2.1e-4
                 LO CA x AS 44 = Sqrt(0.3 * 3.2e-11)    = 3.1e-6
AS MICH  @55MHz: AS CA x AS 55 = Sqrt(15 * 6.0e-5) ε    = 3.0e-2 ε  ==> DARM@55MHz 9.0 ε
AS MICH  @BHD:　 LO CA x AS CA = Sqrt(0.3 * 15) ε       = 2.1 ε     ==> DARM@BHD   6.3e2 ε

I'm checking Koji + Yuta's not-so-naive calculations using finesse.

PRMI Carrier resonant:
- The HD phase signal @44 MHz is estimated to be 386.5 times stronger.
- The MICH signal @BHD_DIFF is estimated to be enhanced by a factor of 299.75.

PRMI Sideband resonant:
- The HD phase signal @44MHz is estimated to be () stronger.
- The MICH signal @BHD_DIFF is estimated to be suppressed by a factor of

PRFPMI: Now the carrier and the 11 and 55MHz sidebands are resonant.
- The HD phase signal @44MHz is estimated to be ().
- The MICH signal @BHD_DIFF is estimated to be the same level as the one with PRMI Carrier resonant.

[Mayank, Paco, Yuta]

IFO alignment is not good.
It seems like the input pointing drifted a lot during PRMI and noise measurements, and beam spot on both ITMY and ITMX are not good.
They are so off from the center (by about a beam size mainly in yaw) that ASS cannot handle.
Current situation is as attached (compare with good alignment in March 23 40m/17521).
Yarm ASS is not working, Xarm ASS is not working, POP is clipped, AS is clipped

Message: Always check the alignment from TTs using BHDC_A/B, and always check the arm alignment, even if you are only doing PRMI. (Follow the steps in 40m/17277)

I suppose ASS Y arm is using PR2/3 to align the beam to the arm.
Can't we have ASS PRM bring the beams to the center (or some defined places) of the PRM and PR2 by moving the TTs?

[Yuta, Mayank]

UPDATE: It turned out that the pair of 0.3 OD ND filters we used were not matched. So we replaced them with new 0.5 OD NENIR05A-C from thorlabs. Now both the photodiodes give similar count.

The DC power incident on the PDs is 74 mW which may cause saturation. We attenuated the beam going to BHD_DC Photodiodes using ND filter of OD 0.3 which gives attenuation of 0.5. 

[Yuta, Mayank, JC, Paco]

We fixed the IFO nominal alignment.

1. Yuta and Mayank had worked all morning and into the early afternoon to try and recover alignment. We noticed a few things seemed off:
   1. ASS loops still wouldn't work.
   2. ITMX oplev loops were weirdly unstable, but we suspected this had to do with the recent HeNe replacement saga.
      1. Paco revisited the setup, suspecting a lens near the QPD was wreaking havoc. This was not the case, but the setup now resembles the previous one. Furthermore, an iris was placed in the input ITMX OpLev path.
   3. Using AUX (green) beams as a reference didn't really work well.
2. We decided to check the SUS rack electronics where some noise measurements were carried out last week.
3. We found out that between the DW boards from ITMX and ITMY to the coil driver units for ITMX and ITMY there were two crossed wires at least (Ch4).
4. Yuta and Paco reconnected all channels between the ITMX DW to ITMX Coil driver and ITMY DW to ITMY Coil driver units,
   1. All wires seemed to be crossed when going up the rack... suspicious...
5. The first damping test failed, and we realized placing an offset in ITMY coils affected ITMX, so the DW board units were probably flipped because they were probably mislabeled!
6. Yuta and JC swapped the cables again, and we ran a coil by coil test before damping. After this ITMs were successfully damped, so the labels were corrected in the AI + DW boards to prevent this confusion in the future.

• IFO alignment was recovered by Yuta and Paco.
  • ASS now works again!
• JC and Mayank aligned OpLevs
  • Loops were closed and remained stable in ITMs.

Attachment #1 shows the alignment state at the end of this work.

[Mayank, Radhika, Paco]

We locked PRMI for a solid hour and controlled LO phase angle using BH55_Q at higher power.

After Radhika aligned the IFO for us, and recovered the PRMI flashing (using REFLDC), we attempted a PRMI lock. After a few trials we succeeded.

Control parameters: see Attachment #1, basically REFL11_I to PRCL, and AS55_Q to MICH (error points) and actuation as previous locks with PRCL to PRMand MICH to 0.5 * BS - 0.33 * PRM.

The gains are slightly different, and in particular PRCL gain was increased from -0.07 to -0.09 after an OLTF estimated the UGF could be increased to > 120 Hz (Attachment #2 shows the measured OLTF) Do note we ended up disabling the FM1 on PRCL LSC filter bank (a boost) because we thought the loop was unstable when it got triggered ON. Finally, we took a quick noise spectrum of PRMI, and we have yet to calibrate it.

We also managed to reduce the AS_DC level from 0.4 to 0.1. We first tried to add an offset to MICH error point but the trick was to align the ITMX ITMY differential yaw.

Lock start Time: 1367107965 --> 1367111565

While PRMI was locked, we quickly locked homodyne angle using BH55_Q. For this the demod angle was optimized from -60 deg to 55.374 deg. The lock was acquired using FM5 and FM8 with a gain of -0.75. Attachment #3 shows the "calibrated" noise budget of the LO phase under this configuration. The main difference with respect to the previous  budget is in the "RIN" which we now realize is not relative... therefore the increase in this budget. We will revisit this calibration later.

- Next steps

• Re-calibrate LO phase noise with high power
• Investigate BH44 control
• Calibrate PRMI noise for budget
• Estimate LO phase sensitivities at MICH vs PRMI

[Paco, Yuta]

Measured power recycling gain at POP is 10(2), consistent with our expectation.

We measured power at POP with ITMY single bounce and estimated power recycling gain in PRMI.
As POP RFPD (Thorlabs PDA10CF; used for POPDC, POP22, POP110) was saturating, we attenuated the input power by OD2.5 ND filter.
Power recycling gain was estimated to be 10(2), roughly consistent with our expectation of 13.2 (40m/17532).

What we did:
 - Realigned POP path in ITMX table after aligning the IFO. It turned out that when POP power measurements were done in 40m/17532, POP was not well aligned.
 - We measured the power with ITMY single bounce at POP right after the viewport and in front of POP RFPD.
 - We also measured counts in C1:LSC-POPDC_OUT under ITMY single bounce, PRMI carrier locked, and MICH locked with PRM misaligned, with different ND filters.

Results:

 - Estimated power recycling gain is 1600(300) / (9.0(6) / 5.637%) = 10(2) .

Expected values:
 - Expected power using PSL output of 890 mW (measured in elog 40m/17390) under ITMY single bounce at POP is the following, and is consistent with the measurement.
[a] 890 mW * 0.9 (IMC transmission?) * 5.637%(PRM) * (1-2.2%)(PR2) * 50%(BS) * (1-1.384%)(ITMY) * 50%(BS) * 2.2%(PR2) = 0.240 mW

 - Calibration for C1:LSC-POPDC_OUT into power at POP RFPD is
[b] 437 counts / 0.108 mW = 4.0e3 counts/W.

 - Thorlabs PDA10CF has a transimpedance gain of 1e4 V/A and output range of 0-5 V. So, the saturation happens at 5 V / (1e4 V/A * 0.8 A/W) = 0.625 mW. We ended up attenuating POP RFPD with OD2.5 to make it not saturating (0.4 mW on the PD with PRMI carrier lock).

[Yuta, Paco]

We attenuated RFPD BHD paths to prevent saturation

To prevent saturating RPFDs, we added ND filters along BH44 and BH55 paths. We calculated the optimal filters to be used by taking into account the previously measured DC levels at both RFPDs as well as their DC transimpedances.

BH55 (S/N 117, former POP55) DC transimpedance is reported to be 10010 V/A. Assuming a responsivity of 0.8 A/V, we expect 8008 V/W at DC. When PRMI is locked, we have measured 10 mW of light incident on this PD such that it gets saturated. Then we installed an OD ~ 1 filter to drop the power to 1 mW such that at most we get 8 VDC (< 15 VDC rail).

BH44 (S/N 115, former unknown) DC transimpedance is estimated to be 645 V/A. Assuming 0.8 A/V, we expect 516 V/W at DC. This RFPD gets 27 mW when PRMI is locked, giving a slightly saturated PD> Then we installed an OD ~ 0.5 filter to drop the power to ~ 8 mW such that we at most get 4 VDC (< 15 VDC rail).

[Mayank, Paco]

We calibrated PRCL displacement using MICH and estimated (?) BS angle to MICH couplings

Expt 1 - calibration of displacements for PRMI

We injected calibration lines at four different frequencies (211.11, 313.13, 575.17 and 1418.93) into (ITMY) under PRMI configuration and recorded the calibrated MICH displacement (C1:CAL-MICH_W_OUT) and uncalibrated PRCL displacement (C1:CAL-PRCL_W_OUT). The exctation amplitudes were (100,150,250 and 1000 cts) respectively.

The ratio of intensities of calibration lines peak in the two configurations are used to caliberate the PRCL displacement (C1:CAL-PRCL_W_OUT). Basically, if MICH = Lx - Ly and PRCL = Lp + 0.5(Lx + Ly), then PRCL displacement from Ly is half of MICH displacement.

The estimated optical gain (C_INV) was 6.41e-11 cts/m, which we added into FM3 of PRCL calibration filter bank. Attachment #1 shows the calibrated displacement spectra.

Expt 2 - angle to length couplings

After calibrating PRCL displacement, we tried to estimate the angle to length coupling from BS PIT/YAW to MICH under the PRMI configuartion. We started by injecting a broadband guassian noise (3000 cts amplitude in the 7-17 Hz band for PIT, and 17-27 Hz band for YAW) through an 8th order Cheby II filter with 80 dB attn to shape the noise before injecting into BS ASCPIT/ASCYAW.

We then looked at the increased displacement noise in the calibrated MICH and PRCL displacements. Assuming a naive 1 urad/count / f^2 of BS angular actuation strengths in both PIT/YAW, we estimate the couplings to be:

• BS PIT to MICH = 0.12 nm / urad @ 13 Hz
• BS YAW to MICH = 0.19 nm / urad @ 22 Hz
  • BS PIT to PRCL = 0.38 nm / urad @ 13 Hz
• BS YAW to PRCL = 0.08 nm / urad @ 22 Hz

Seems a bit too large... bogus? Attachment #2 summarizes these measurements.

[Yuta, Paco]

We locked PRMI-BHD (LO phase was controlled using BH44_Q)

Today we worked with PRMI carrier locked using AS55_Q and REFL11_I (to control MICH and PRCL respectively).

PRCL and MICH displacement calibration

We calibrated the PRCL and MICH displacements. This time we injected lines on (ITMX - ITMY) for MICH and PRM for PRCL. The optical gains were found to be

• (ITMX - ITMY) to AS55_Q = 2.04e10 counts / m
• PRM to REFL11_I = 1.66e12 counts / m

We added these into the C1:CAL_MICH_CINV and C1:CAL_PRCL_CINV filters on the calibration model.

PRMI-BHD handoff

After the lock was established and the alignment refined, we tried locking the homodyne phase angle using BH55_Q. We could not close the LO_PHASE loop with this sensor, so we resorted to using the BH44_Q. To do this we actually changed a few things:

1. The BH44 whitening filter gain was lowered from +39 dB to +21 dB.
2. Rotated the ND filter wheel to avoid saturation on the BH44 RFPD from 0.5 to 1.0. This corresponds to a change of ~33% in the incident BH44 light.

While we managed to lock BH44 by actuating on LO1, the lock was not very robust (typical lock acquistion using FM5 and FM8)... so we switched to actuating on AS4 which made the LO PHASE loop slightly more robust.

In preparation for handoff, we turned on a line at 211.11 Hz (MICH osc) and demodulated the BHDC_DIFF to estimate the sensing matrix element.

• BHDC_DIFF to AS55_Q ~ 25

After using this number to rescale the MICH_B error point, we handed off from MICH_A (under AS55_Q control) to BHDC_DIFF. Our lock stretch covered the following gpstimes:

• PRMI-BHD lock = 1368235235 to 1368235264

During the lock stretch above, we managed to take some noise spectra for the calibrated MICH and PRCL displacements. Attachment #1 shows the comparison between PRMI and PRMI-BHD configurations.

Discussion

• Looking closely into Attachment #1 you'll find a *BH44_Q trace in green. This trace represents the uncalibrated LO phase error point. We measured the UGF to be < 20 Hz (C1:HPC-LO_PHASE_GAIN=1.2), so above 20 Hz, this trace is shown just as a guide for the noise shape. It would seem that the MICH displacement in PRMI-BHD readout is getting its shape from this noise and therefore might be limited by it.

Next steps

• Calibrate LO phase at BH44 and see if it scales as predicted by our calculations.
• Optimize BH44 control; why can't we lock this phase for longer?
• Noise budget.

[Mayank, JC]

STACIS Vibration Cancellation Isolators contain a PCB board called the Compensator board. These are boards that "allow you to control the feedback to the PZT stacks." The board is essentially held up by the 2 rear plugs and 3 screws on the front rim (Highlighted in Yellow). You don't need to disassemble the entire islotar to remove this, you just need to loosen the tension screws and pull out softly. Attachment #4 shows the seat made for the board to be placed, highlighted in Green. When placing the board back into its original position make sure in slips into this slit nicely. The extender/compensator board is part of the STACIS Isolator and each Isolator should have this. Each board seems to haver it's own serial # but not an actual part #. On this board, the S/N is 033509.

Over the past few days I have been trying to understand the existing sensor and heater related hardware by manual inspection and combing elogs. From what I understand, I believe a lot of the hardware was built from scratch by Kira in 2017-18. She put in place the insulation, built the sensor and heater circuits and installed and interfaced everything with EPICS. This let her successfully do step response tests and also execute PID control of the temperature of the can. As suggested by Paco, I am trying to summarise my findings in this elog. This is the block diagram of the overall system.

In the lab I was able to locate two identical temperature sensor boards, one for monitoring ambient temps and another for the can temp, which has a sensor attached to the inner seismometer can. Attachment 1 shows the actual board.

The schematic for the temperature sensor can be found here. It was later clarified that she is using AD590 and not the AD592. I tested the ambient sensor board by hooking it up to an oscilloscope and heating the sensor up. It seems to work like she described, and the output voltage goes down with heat. I will later figure out interfacing it with an ADC and calibrating it if I cannot find Kira's old work related to this. The setup there also has +/-15V Sorensen's for power (I probed these and they work), a BNC for temp readout and a bunch of other wiring for the heater. This wiring comes from the nearby rack which should have the heater circuit, but I haven't yet been able to locate it because there is too much stuff.

Coming to the heater circuit - I found the schematic for it here. I am still unsure about what the power range it can operate over, but this plot seems to imply it saturates at around 55W. This circuit underwent many different iterations so I am unsure what load resistance was actually used finally and it is not clear from the elogs. It might be a pair of heaters combined in series or parallel. Additionally, this elog by Shruti from June 2018 implies that the original circuit that Kira made ended up breaking at several different points. She said there were attempts to fix it, but I cannot find any updates after that and I think her SURF ended. I don't know the current status of the heater circuit. I am not sure where it is stored.

I was hoping to utilise the old EPICS channels set up by Kira for heater control as well as sensor readout to verify if everything was still functional and initially just read out the temperature of the can and find out how much it fluctuates. I planned to later also try to replicate the PID results. But Paco explained how the Acromag system worked and told me that utilising the old channels will not be possible right now, as all the channels have been used up for more critical tasks and none of the old interfaces that Kira had set up can be used now, even if the hardware was fine. 

Also, the can temperature sensor board has a wobbly solder joint at one of the power connectors, and we cannot move it to the lab because the sensor is anchored to the inner can. There is no power indicator LED to signal if the connection is secure so its kind of unusable right now. Paco and JC told me that soldering near the X end is not possible because the fumes would harm the optics. We will look for solutions to this. One option would be to make an entirely new board and keep a mechanical connector for the sensor. 

I wanted to mention here that I have a printed circuit board design (LIGO-D1800304) for using AD590 as temperature sensors. I believe printed boards and all required components are stored on the wire shelf in the WB EE shop on a box labeled with this DCC number. This circuit is also meant to be read by Acromag, maybe it can come of some use to you. You can check out the use in CTN lab in WB near the south-east end of the table.

[Paco, Yuta]

RF FPMI is recovered after c1sus DAC-0 card replacement

Summary:
 - We wanted to check if FPMI locks after DAC-0 card relacement (40m/17620).
 - 60 Hz noise similar to what we saw in February prevented us from locking FPMI stably, but fixed it by turning off FM9 of coil output filters in MC1 and MC3 (40m/17462).
 - There are slight changes in locking gains, but it now locks reliably.

FPMI locking:
 - MICH: 1 for REFL55_Q, MICH_GAIN=18 (used to be 11) gives UGF of 45 Hz
 - DARM: 1 for AS55_Q, DARM_GAIN=0.044 (used to be 0.04) gives UGF of 134 Hz
 - CARM: 0.567 (used to be 0.496) for REFL55_I, CARM_GAIN=0.011 gives UGF of 224 Hz
 - Attachment #1 shows all the OLTFs.

60 Hz noise:
 - FPMI locking was not stable, and we moved back to YARM locking to see if 60 Hz noise is higher or not.
 - Attachment #2 shows 60 Hz noise measured with MC_F and YARM. The noise was actually similar to what we saw in 40m/17461, so we checked MC1 and MC3 dewhitening
 - FM9 of coil output filters was turned on for some reason (probably because of burts we were doing when fixing c1sus). MC1 and MC3 FM9 ELP28 filters should be off.
 - This made FPMI locking stable and 60 Hz noise lower by more than an order of magnitude (Attachment #3).

Followed the instruction on this elog to restart the rsync server daemon

controls@nodus|etc> sudo systemctl start rsyncd.service
controls@nodus|etc> sudo systemctl enable rsyncd.service
controls@nodus|etc> sudo systemctl status rsyncd.service
● rsyncd.service - fast remote file copy program daemon
   Loaded: loaded (/usr/lib/systemd/system/rsyncd.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2023-06-21 21:00:44 PDT; 13s ago
 Main PID: 13146 (rsync)
   CGroup: /system.slice/rsyncd.service
           └─13146 /usr/bin/rsync --daemon --no-detach

Jun 21 21:00:44 nodus.martian systemd[1]: Started fast remote file copy program daemon.
Jun 21 21:00:44 nodus.martian systemd[1]: Starting fast remote file copy program dae.....
Hint: Some lines were ellipsized, use -l to show in full.

if systemctl was handling it, how come it died? Or did someone kill it on purpose? I wish we had a tool like Monit or Nagios running to tell us about these things.

[Many]

The large optical table (5ft x 12ft x 2ft, previously called SP table) was moved from the 40m lab. (Attachment 1)
The contractor did a professional job and successfully transported the optical plate to the Synchrotron building without damaging the 40m facility.

JC came early in the morning to work on the final preparations. Some others were on standby at 8 AM. The arrival of the contractor got delayed due to traffic. The actual work began at 10 AM.

(10AM) The contractor first spent ~90min assembling a hoist around the optical table. It was necessary to remove some fluorescent light tubes and their covers because of the height of the hoist. (Attachment 2)

(11:30AM) Once the hoist was assembled, the optical table was tilted vertically using a sling and a chain block. (Attachment 3)

(12AM) The table was placed on dollies narrower than the table width (2ft) and rolled to the south end door. Thanks to our careful preparation, this process was smooth and took only 10 minutes. (Attachment 4)
A compact forklift was used to get over the end door (Attachment 5). Once half of the table was exposed outside, a larger forklift lifted the entire table and swung it out from the lab building (Attachment 6). After it was tipped horizontally, it was laid on a gigantic truck with the same forklift (Attachments 7/8). (1 PM)

The photos and videos are collected in the 40m google photo.

[Mayank, Hiroki, Koji]

Once we reached 1~2mtorr, we opened the PSL shutter.

The IMC was immediately locked and aligned with the WFS.

The PRM/SRM looked very much aligned. We could see the MI and two arms fringing.

The two arms were manually aligned and the Y arm was aligned with the ASS.

IFO alignment is in a strange state.
BHD is not fringing, and misalignment script is not working properly

IFO alignment status
 - YARM ASS is working
 - XARM ASS is not working (because of ETMX coil driver upgrade)
 - Attached is the current alignment when YARM and XARM are both aligned, AS4 misaligned. Powers at photo diodes are as follows.

>cdsutils avg -s 10 C1:PSL-PMC_PMCTRANSPD C1:IOO-MC_TRANS_SUMFILT_OUT C1:LSC-TRY_OUT_DQ C1:HPC-BHDC_A_OUT C1:HPC-BHDC_B_OUT C1:LSC-TRX_OUT_DQ
C1:PSL-PMC_PMCTRANSPD 0.688543850183487 0.0010497113504850193
C1:IOO-MC_TRANS_SUMFILT_OUT 13378.8802734375 58.42096336275247
C1:LSC-TRY_OUT_DQ 1.0218201756477356 0.006230110889854089
C1:HPC-BHDC_A_OUT 34.033762741088864 0.1877582940472513
C1:HPC-BHDC_B_OUT 33.95858993530273 0.1951729492341625
C1:LSC-TRX_OUT_DQ 0.9446217834949493 0.01777568349190775

 - After this, we usually misalign ETMY, ETMX, ITMY to have LO-ITMX fringe in BHD DCPDs (elog #17277), but it seems like it is hard to see the fringe by aligning AS beam with SR2 and AS4 we usually use.
 - Also, misalign/restore script we use are not working properly. Alignment changes a lot when restored after misalignment.
 - We also found that "gain_offset" of gain(0.48) for ETMY coil outputs was turned off.  This changed the alignment offsets to get the correct alignment. This probably also affected LSC.

Next:
 - Recommission XARM ASS with updated ETMX coil driver
 - Check the "gain_offset" filter for ETMY and update relevant gains
 - Check the misalignment script.
 - Align LO-AS fringe

Before any trial at the ETMX suspension, ETMX coil driver "Run" mode (a sort of dewhitened mode) is ON at the coil driver. The "Binary Input" short plugs should be modified to turn them to "Run" mode.

[Yuta, Hiroki]

BHD alignment has been restored

We aligned the AS beam (reflection of ITMX) and LO beam and maximized the fringing of the BHD differential signal (Attachment 1).
We used LO1, SR2 and AS4 for the alignment and the result parameters are shown in Attachment 2.
 

Procedure log of BHD alignment

Alignment of LO beam:

• ETMY, ETMX and ITMY were misalinged during this BHD alignment
• Misaligned SR2 to have only the LO beam in BHD DCPDs
• Tuned LO1 so that the LO beam comes to the previous position in the video

Alignment of AS beam:

• Restored SR2
• Tuned AS4 so that the AS beam comes to the position of LO beam
• Repeated the followings for the pitch and the yaw until the fringing was maximized:
  • Misaligned AS beam using SR2
  • Restore the alignment of AS beam using AS4
  • If the fringing gets worse, it means that you moved SR2 in the wrong direction. Move the SR2 in the opposite direction next and repeat the procedures above.
  • If the fringing gets better, it means that you moved SR2 in the correct direction. Continue the procedures above.

"gain_offset" for ETMY coil outputs has been turned on

As mentioned in elog #17671, the "gain_offset" of gain(0.48) for ETMY coil outputs had been turned off for some reason.
I have turned on all of the "gain_offset" for ETMY coils and have changed the alignment offsets for ETMY to compensate the effect of "gain_offset": 

P: 2703 -> 5631
Y: -2296 -> -4783

After the operation above, I confirmed that the Y arm is flashing and the OPLEV laser is hitting on the QPD.

[Yuta, Yehonathan, JC]

We have moved a Smaller Table and moving forward with preparing a clean room.

What we did:
  - Moved the 3 ft x 4 ft Optical table which was by the red toolbox next to the 1X2 Power Supply Rack.
  - Moved the Portable HEPA Filter (which was used during the BHD Vent) from ITMX Chamber

Summary:

     · Moved the 3 ft x 4 ft Optical table which was by the red toolbox next to the 1X2 Power Supply Rack.

Yehonathan and I cleared off this table and disconnected any power connections that were running to it. There was a grounding cable that was bolted down to it and safely removed. Next, I used the manual forklift to lift one side of the table while Yehonathan rolled a piano dolley under the table support. Following, we did the similar procedure on the other side of the table and safely sat the table onto piano dolleys. We rolled the table over and placed it into it's new position by the 1X2 Power rack. To take off the piano dolleys, I used the forklift once again. Yehonathan held one side still to prevent the table from rolling away dangerously, and Yuta slid the Piano dolley out from under the table. Next, we lifted the other side and slipped the other dolley out of the table similarly. once the table was sat down, we re-leveled the table.

     ·Moved the Portable HEPA Filter (which was used during the BHD Vent) from ITMX Chamber

I rolled over the the protable HEPA filter from ITMX Chamber. The height of this was too tall to clear the short ceiling by the PSL table. Yuta and I have to lean the HEPA sideways to clear this and we did so smoothly. The HEPA fit perfectly around the optical table. I will wipe down the table contact Maty to see if we have a proper cleaning procedure for this. I would prefer to add more of the plastic drapes to enclose the table, but we can use plastic Mylar sheets in the mean time. 

[Yuta, Hiroki]

Calibrations of the actuators have been done

Summary of calibration:

AS55_Q in MICH : 1.16e9 counts/m 
BS        : 26.19e-9 /f^2 m/counts
ITMX    : 5.07e-9 /f^2 m/counts
ITMY    : 4.80e-9 /f^2 m/counts
ETMX  : 10.99e-9 /f^2 m/counts (matched to ETMY with the gain of "x0.414" put in coil outputs filter bank. Without "x0.414", 26.52e-9 /f^2 m/counts was measured.)
ETMY  : 10.99e-9 /f^2 m/counts
MC2    : -14.27e-9 /f^2 m/counts in arm length
MC2    : 5.10e-9 /f^2 m/counts in IMC length
MC2    : 1.06e+5 /f^2 Hz/counts in IR laser frequuency 

Methods

Calibration of MICH error signal:
To calibrate the MICH error signal (C1:LSC-AS55_Q_ERR), we followed the same free swinging method as elog #17285 and #16929 but used the update code: scripts/CAL/OpticalGain/getOpticalGain.py.
By fitting the X-Y plot of AS55_Q and  ASDC, we obtained 1.16e9 counts/m (Attachement 1).

Actuator calibration of BS, ITMX and ITMY:
We followed the same method as elog #17285 and #16929. 
We locked the MICH with UGF of ~10 Hz and measured the transfer function from C1:LSC-BS,ITMX,ITMY_EXC to C1:LSC-AS55_Q_ERR above the UGF.
By using the optical gain, measured transfer functions were calibrated to the actuator transfer functions of BS, ITMX and ITMY (Attachment 2).
Fitting code: scripts/CAL/MICH/MICHActuatorCalibration.ipynb

Actuator calibration of ETMX, ETMY and MC2:
We locked the X(Y)ARM with ITMX(Y) and measured the transfer function from C1:LSC-ITMX(Y)_IN2 to C1:LSC-X(Y)ARM_IN1. 
With this measurement, we can directly obtain the transfer function of (Optical gain)*(Actuator of ITMX(Y)), which is not affected by the 1/(1+OLTF) suppression (We should have done the same method for the calibration of BS, ITMX and ITMY).
Then we changed the actuator to ETM(X) and MC2 and measured the transfer functions from C1:LSC-ETMX(Y),MC2_IN2 to C1:LSC-X(Y)ARM_IN1. respectively (Attachment 3,4).
By fitting the ratios between the measured transfer functions, we obtained the actuator transfer functions of ETMX, ETMY and MC2 (Attachment 5,6,7).
Saved diaggui templates: measurements/LSC/(XARM;YARM)/(XARM;YARM)_(ITMX,ETMX,MC2; ITMY,ETMY,MC2)EXC_Template.xml

Balancing the actuation of ETMX and ETMY:
The obtained actuator transfer function of ETMX(Y) was 26.52e-9(10.99e-9) /f^2 m/counts.
The result for ETMY was consistent with elog #16977 but that for ETMX was ~10 times larger than elog #16977 because of the new ETMX coil driver.
To balance the ETMX and ETMY, we added the gain of “x0.414” to the coil output filter bank of ETMX.
Also, in order not to change the OLTFs, we added the gain of “x2.42” to the LOCK FILTERS of ETMX and changed the gain values of the damping filters.

Compared the network settings between some of the machines.

It seemed that we can write network settings into /etc/network/interfaces. (Comment lines omitted)

source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

pianosa has the same content, but I found chiara has much more elaborated lines. So I decided to put the details there.

source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

auto eno1
iface eno1 inet static
      address 192.168.113.215
      netmask 255.255.255.0
      gateway 192.168.113.2
      dns-nameservers 192.168.113.104
      dns-search martian
      dns-domain martian

And just in case ifup was ran

$ sudo /sbin/ifup eno1

This made rossa connected to the wired network as rebooted.
So reactivated the NFS line in /etc/fstab
Rebooting pianosa brought it back to the nominal operation. Victory.

I looked at the Acromag situation of c1psl to prepare for the PSL air flow speed sensor.
Someone clever did a great job of binding all the spare channels into DB37s.

The pin-outs and channel assignments are all listed in a Google spreadsheet. The link can be found on the following wiki page.

https://wiki-40m.ligo.caltech.edu/CDS/SlowControls/c1psl (Click "Feedthrough wiring with test status")

According to the spreadsheet, we are supposed to have

• 14 DAC CHs
• 14 ADC channels
• 15 sinking BIO channels
• 12 sourcing BIO channels

For now, we can hook up the sensors via a DB37 breakout or even just a connector. If we have many cables coming in the future, we can make a breakout 1U unit.

Mode-matching breadboard has been constructed

I have constructed the mode-matching breadboard for aligning the BHD OMCs.
I also measured the profile of the resulting beam:

Beam waist X: 496 +/- 2 um
Beam waist Y: 504 +/- 3 um
Waist position X (from the front surface of the collimator mount): 224 +/- 1 cm
Waist position Y (from the front surface of the collimator mount): 236 +/- 2 cm
Maximum mode-matching efficiency to OMC: 99.78 +/- 0.07 % (if the waist of the OMC eigen mode is place at 230 cm)
(OMC eigen mode: 489.6 um (horizontal), 490.5 um (veritical))

The details are shown in the following attachments:

• Attachment 1: Current configuration and summary of beam profile
• Attachment 2: Resulting beam profile
• Attachment 3: Photo of mode-matching bread board

This post is reprinted from the elog of Ando Lab at the University of Tokyo.
[Author: Satoru Takano]

Recently some people are interested in ADC/DAC noise of Moku:GO. I measured them, and found that ADC noise is much larger than expected (quantization error).
I used "PID Controller" module for the measurement of ADC/DAC noise.

DAC Noise

I set up the module as follows:

• Input channel: open, no input
• Output channel: ch1

I took data by data logger DL-750 and calculated PSDs by myself. Measured DAC noise is shown in Fig.1.

I modeled the noise spectrum by:
​

ADC Noise

I set up the module as follows:

• Input channel: ch1, terminated by 50Ω
• Output channel: ch1
• Filter: Flat, 50dB amplification

I took data by data logger DL-750 and calculated PSDs by myself. Measured ADC noise is shown in Fig.2.

I modeled the noise spectrum by:

Comparison with Theoretical Value

I estimated quantization error of ADC/DAC. Specification of the inputs/outputs are as follows:

• Sampling rate: 125 MHz
• Bit number: 12 Bit
• Voltage range: ±5V, 10Vpp

From these specifications, the estimated quantization noise is . I plotted measured noise and this estimation noise in Fig.3.

Comparing with this value,

• DAC noise: the floor level is almost the same as the estimated quantization noise. Below 1.4kHz an additional 1/f noise exists.
• ADC noise: the floor level at 100kHz is about 10 times larger, and at 100Hz about 100 times larger than the estimation. Below 46Hz another 1/f noise exists.

There is a measured data about ADC noise of Moku:Lab at here. Comparing with this, ADC noise of Moku:GO has a stranger shape than that of Moku:Lab.

Summary

If we are using Moku:GO and worried about sensitivities, we should insert some whitening filter before the input of Moku:GO.

Repeating ADC/DAC noise measurements

I carried out the same measurements of the Moku:Go ADC and DAC noise to compare to the results from Ando Lab. Instead of a flat filter with 50dB of gain, I used the uPDH box fitted filter shape. I recorded spectral densities with an SR785; results are in Attachment 1. These measurements are consistent with those measured in Ando Lab. I included the SR785 noise floor, measured by terminating its input.

DAC noise measurement with single-tone input

Next I tried to measure the Moku's DAC noise using its Waveform Generator and Digital Filter Box in multi-instrument mode. I generated a single-tone digital signal and passed it to an elliptic bandstop filter (fit tightly around the tone). The filtered signal was measured by the SR785. I performed this measurement with 1 kHz and 10 kHz tones [Attachement 2]. While the fundamental peak is suppressed, we still see it and its harmonics (not DAC noise). The floor of these measurements is consistent with the DAC noise reference from the first test, and we can say that the Moku:Go's DAC noise above 100 Hz is below 1 µV/rtHz.

Further ADC noise measurements to come.

The raw frame file is stored in /frames at fb. Before the disk space is flooded, the wiper script deletes the old raw frame files.
I wonder what the state of the wiper script is.

There are wiper scripts (wiper.pl) in /opt/rtcds/caltech/c1/target/fb and /opt/rtcds/caltech/c1/target/daqd, but they no longer seemed to be in use.

I went around the machines and found a service on fb

controls@fb1:~ 0$ sudo systemctl status rts-daq_wiper
● rts-daq_wiper.service - Remove old frame files to reclaim space for the new frame files
   Loaded: loaded (/etc/systemd/system/rts-daq_wiper.service; static; vendor preset: enabled)
   Active: inactive (dead) since Fri 2023-08-04 20:00:27 PDT; 9min ago
  Process: 5355 ExecStart=/opt/rtcds/caltech/c1/scripts/daq_wiper -d /frames -t 2.5 (code=exited, status=0/SUCCESS)

This python version of the wiper script (/opt/rtcds/caltech/c1/scripts/daq_wiper) is running since the last year.
According to the explanation found in the script, the trend data is kept saved, while the raw data is kept deleted to save the specified amount of space (0.25TB it says).
I think this is the configuration we want. So the script was left untouched.

I just wanted to take the same time series data I took back in 2012 (40m/6874).
ALS noise look much better than 2012, but MICH contrast during both arms hold on IR resonance with ALS looks pretty bad compared with 2012, which indicate unbalance of the arms.

I measured the Moku:Go and Moku:Pro delay using a Agilent 4395A network analyzer. I considered the PID controller (0 dB gain); the IIR filter box with a 2nd-order low-pass filter; the FIR filter box with 2 coefficients and 201 coefficients (both low-pass). The current XAUX laser lock is done with a Moku:Go using the IIR filter box, so we would expect ~12 µs of delay.

[Yuta, Yehonathan, JC]

The Frame for The Cleanroom has Constructed and Placed.

What we did:
  - Put together the Clean room frame.
  - Lifted and placed the cleanroom into.

  - Temporarily moved the portable HEPA to the side.
  - Disconnnect the HEPA Booth.

Summary:

     · Put together the Clean room frame.

In the mornings, I have been coming in and assembling the frame one side at a time. Today I finish by attaching all the part together. It does still feel a bit wobbly at the bottom, but theis will be more fixed one I add a cross beam in the backside and bolt the legs to the ground.

Here are the results for Moku Go/Pro delay measurements with the filter shapes removed [Attachments 1, 2]. The PID controller, IIR filter, and FIR filter were all flat in magnitude and phase. The PID controller was the same as before: P=1, I=D=0. The IIR filter was given the form H(s) = 1. The FIR filter was given an exponential form e^(-10t), as done here. The configurations for the Moku:Go (same for the Pro, just 10x higher sampling rate) can be found in Attachments 3-5.

The Agilent 4395A was used once again for measurement. Excluding the FIR low-pass with 201 coefficients, the old measurements with low-pass filters and these flat filters have consistent delay. The Moku:Go IIR filter box used for locking the green laser would still give us a delay of ~12 seconds.