Beam spot position measurements were done, oplevs aligned.
Attachment #1 shows IFO alignment with PRFPMI BHD aligned.
Attachment #2 shows oplev values.
Attachment #3 shows the history of beam spot position measurements since Saturday.

Updates on beam spot position measurements:
 - PR2 mass and moment of inertia were updated using the numbers from Solidworks model (40m/17937).
 - Script to measure all of them were prepared. This script still requires human to check the alignment and locking status. /opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureAllBeamSpotposition.py
 - Script to plot the history: /opt/rtcds/caltech/c1/Git/40m/scripts/ASC/plotBeamSpotPositionMeasurements.py

FROM THE POINT OF VIEW OF IFO, WE ARE READY TO VENT

Update Wed Nov 1 10:58:48 2023

All vertex suspensions are now under software watchdog logic. I tested all of them similar to what we did yesterday with ETMX.

FROM THE POINT OF VIEW OF WATCHDOG (SUS), WE ARE READY TO VENT

We came back to the OMC 24 hours later and found the bonding work yesterday went well.

We cleaned up the OMC further and then placed it on the BHD platform. Now it's ready for the optical action.

Entrance particle count 2 / Exit particle count 4 for 0.5um

(Bond inspection photos will be posted here by JC)

[Koji, Paco]

WE NEED TO IMPLEMENT SOFT WATCHDOGS FOR ALL VERTEX SUSPENSIONS BEFORE WE VENT TOMORROW.

We just need to replicate what was done in (40m/17941) and test.

[Koji, Paco, Yuta]
We implemented the ETMX software watchdog "level 1", meaning the logic disables the SUSPOS/SUSPIT/SUSYAW/OLPIT/OLYAW damping loops whenever the UL/LL/UR/LR/SD PD VAR calculated as soft epics channels in /cvs/cds/caltech/target/c1auxex/ETMXaux.db exceed the PD MAX VAR value stored in C1:SUS-ETMX_PD_MAX_VAR. To do this, we add the following set of record entries to the db file, for example for a single (UL) PD we add:

and the logic is implemented for all loops by adding entries like:
 

Next, we ssh into c1auxex and run systemctl restart modbusIOC.service

If you haven't done so or the signals are not available in dataviewer, you can add them explicitly into /cvs/cds/rtcds/caltech/c1/chans/daq/C0EDCU.ini

Finally, you may have to run sudo systemctl restart rts-edc_c1sus from c1sus

[Koji Paco]

We decided to invert the signs of the misalignment offset for ETMX to see it changed the stability of the damping servo when the sus was misaligned.
And actually it did.
The first figure is the individual OSEM outputs while 1) aligned 2) misaligned as before 3) misaligned with the new offsets.
The second figure shows the variations of the OSEM values. We can see that the numbers went up when misaligned and during misaligned state (due to instability). These numbers went down to nominal level quickly when the offset signs were inverted.

I noticed that there was an oscillating spot on the ITMX face camera image. I tracked the source down and found it was the motion of the ETMX.
It turned out that the ETMX pos loop was not stable when it was misaligned. It is very dangerous. We would have the wire broken after many hours of a mirror swinging like this.

This is exactly why we want a functioning watchdog.

Prepared the following components around the staging clean booth:

• SOS 2"->3" meal sleeve for thick optic (Attachment 1)
  • To mount 1/2" optic we will need two OD 2" (ID 1.8") x 0.125" Al spacers. -> need to be manufactured
• Other optic mounts (Attachment 2)
  • Vented screws / 1"&2" lens mounts / 1" Polaris mirror mounts

From the ITMX window, I confirmed that PR2 is using the original metal sleeve and the optic is 3/8" thick. (See Attachment 1)

Based on this, I made a SW model to check the mass and the IoM.

== 0.375 inch optic / original sleeve ==

- Mass = 201 grams
- Moment of Inertia (grams mm^2)
Lxx = 1.01e5 (Pitch)
Lyy = 9.41e4 (Yaw)
Lzz = 1.79e5 (Roll)

I measured the Oplev PIT/YAW OLTFs and adjusted the gains to get 0.1 to ~ 4 Hz feedback as is recommended in Gautam's thesis (Fig 3.3 and discussion thereafter). Attachments #1-2 show the measured OLTF and simple expected model using the foton filters and plant. Attachment#3 shows the final filter modules and gains after the changes were done.

Next steps:

• Repeat for PRM, ITMs and ETMs

[JC Koji]

We successfully applied EP30-2 on the OMC #1.

• We brought a scale with 0.01g resolution from Yuta's desk.
• The Black and Decker toaster oven was brought from the bake lab (it was already returned)
• Made two AL cups for epoxy mixing
• Brought an SS spatula from the bake lab.
   
• Checked which bracket has the 50% delamination by lifting the OMC --> it was the one close to the QPDs (Attachment 1)
   
• Used one of the EP30-2 tubes with an expiration date of Nov 1, 2023 (in 2 days!) (Attachment 6).
• Disposed one push from the glue applicator tube into one of the Al cups. Then, poured 7g into the other Al cup.
• Added 0.35g of silica bead powder.
• Mixed -> painted a few drops on a shell of Al foil -> Bake in the oven at 200F for 15min.
• JC and I confirmed the baked test piece was nicely cured. No stickiness. Very crisp.
   
• Applied the bond on the side of the 50% delaminated bracket. (Attachments 2/3).
• I could confirm that the glue was sucked into the gap somewhat. The action was still going. (Attachment 4).
   
• Now, we proceeded to the cable bracket. JC applied the layer of glue to the two brackets.
• Then, the cable bracket was placed -> We checked how the upper part was wet. It was very nicely done! (Attachment 5)
   
• We've placed some weight on the cable bracket so it does not move. In reality, the bracket was well constrained by the four screws and had almost no play to slide. (Attachment 7)
   
• Decided to resume tomorrow at 2:30PM
• The exist particle counting: 0 count for 0.5um particle.

Beam spot position measurements were done again using updated estimate of moment of inertia.
Also, LPF for demodulation is applied with sosfiltfilt instead of filtfilt.

Results:

# Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std    h (mm)    h_std
ETMY    YARM    211.11    100    1382731658    3601.14    50.48    0.22    0.04    -0.14    0.02
ITMY    YARM    211.11    100    1382731730    3616.83    45.92    0.10    0.02    0.06    0.03
ETMX    XARM    211.11    100    1382731794    1397.71    17.22    0.52    0.10    0.42    0.09
ITMX    XARM    211.11    100    1382731852    1600.21    17.47    1.18    0.20    0.09    0.03
BS    MICH    211.11    3000    1382732022    1.50    0.03    2.61    1.29    -2.60    0.95
PRM    PRY    211.11    300    1382732337    237.32    11.38    8.07    1.06    -2.95    0.30
PR2    PRY    211.11    300    1382732455    354.85    6.44    6.79    0.66    0.62    0.05
PR3    PRY    211.11    300    1382732578    276.86    10.08    0.98    0.07    -16.29    1.17
LO1    HPC    113.13    1000    1382733109    3.70    0.08    7.80    1.32    5.18    0.72
LO2    HPC    113.13    1000    1382733180    3.55    0.53    -14.40    2.99    21.47    5.69
AS1    HPC    113.13    1000    1382733248    3.73    0.18    1.69    1.87    15.67    0.92
AS4    HPC    113.13    1000    1382733325    3.70    0.27    -5.84    1.17    13.26    1.79
SR2    HPC    113.13    1000    1382733385    3.41    0.77    1.46    3.05    6.98    3.75

Attached is the comparison between measurements done on Friday and today.

What we did:
 - Updated the code to use scipy.signal.sosfiltfilt instead of scipy.signal.filtfilt.

Wn=0.0001    # Butterworth filter cutoff will be fs*Wn = 1.6834 Hz for fs=2**14 Hz
#[bbb, aaa] = sg.butter(4, Wn)
sosLPF = sg.butter(4, Wn, output='sos')
sin=np.sin(2*np.pi*dmdfreq*time)
cos=np.cos(2*np.pi*dmdfreq*time)
#I = 2*sg.filtfilt(bbb, aaa, data*sin)
#Q = 2*sg.filtfilt(bbb, aaa, data*cos)
I = 2*sg.sosfiltfilt(sosLPF, data*sin)
Q = 2*sg.sosfiltfilt(sosLPF, data*cos)

 - Updated the code to use Solidworks estimated mass and moment of inertia in 40m/17930. PR2 mass and moment of inertia was estimated by removing 0.25 inch thick mirror from "0.25 inch optic / original sleeve" model and adding 3/8 inch optic.

 Mass = # in kg
 {'BS': 0.255,
 'ITMX': 0.255,
 'ITMY': 0.255,
 'PRM': 0.255,
 'ETMX': 0.255,
 'ETMY': 0.255,
 'MC2': 0.255,
 'PR2': 0.199,
 'PR3': 0.235,
 'LO1': 0.185,
 'LO2': 0.235,
 'AS1': 0.185,
 'AS4': 0.185,
 'SR2': 0.235}

MoI = # in kg*m**2
{'BS': {'PIT': 0.000106, 'YAW': 0.000106},
 'ITMX': {'PIT': 0.000106, 'YAW': 0.000106},
 'ITMY': {'PIT': 0.000106, 'YAW': 0.000106},
 'PRM': {'PIT': 0.000106, 'YAW': 0.000106},
 'ETMX': {'PIT': 0.000106, 'YAW': 0.000106},
 'ETMY': {'PIT': 0.000106, 'YAW': 0.000106},
 'MC2': {'PIT': 0.000106, 'YAW': 0.000106},
 'PR2': {'PIT': 0.00010091055503756133, 'YAW': 9.391055503756132e-05},
 'PR3': {'PIT': 9.85e-05, 'YAW': 9.999999999999999e-05},
 'LO1': {'PIT': 9.84e-05, 'YAW': 9.14e-05},
 'LO2': {'PIT': 9.85e-05, 'YAW': 9.999999999999999e-05},
 'AS1': {'PIT': 9.84e-05, 'YAW': 9.14e-05},
 'AS4': {'PIT': 9.84e-05, 'YAW': 9.14e-05},
 'SR2': {'PIT': 9.85e-05, 'YAW': 9.999999999999999e-05}}

/opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureBeamSplotPosition.py

Next:
 - Automate the lock part so that we can run often and do health check of IFO.
 - Check clipping by measuring the power change at each port while dithering.

[JC Koji]

In the preparation of the OMC bond rework, we removed the remaining bond layer on the glass brackets.

Tools: Newly opened acetone, small glass bottle, syringes, Cotton Q-tips (wooden stick), cleaned razor blades

Steps:

• The epoxy layer stayed on the glass bracket surface.
• We first soaked the top of the brackets with acetone, hoping the bond would start to melt.
• We didn't see much difference after ~5 min.
• We started scrubbing the layer with the cotton Q-tips. We hardly saw any change.
• After struggling for ~30 min, some delaminated areas started to peel off, particularly when acetone liquid was applied. (Attachment 1)
• Kept applying acetone while the surface was scratched with a razor blade. We try not to stress the middle part of the glass bracket as it's the most fragile part.
• This process had the risk of being messy. Sheets of the lens cleaning paper were laid out around the cable bracket (Attachment 2).
• All the glue on the brackets was removed. This turned the matte surface shiny and smooth.
• Removed all the messy paper from the OMC. The fragments of the epoxy layers were removed by Kapton tape, acetone flow from syringes, and IPA wiping.
• The result looked like Attachment 3.

Next:

• Apply EP30-2
• The cable bracket seems to keep its position with no position constraint. Nevertheless, we'll place some metal weights around and on the cable bracket.
• The bracket close to the QPDs has ~50% delamination. The bond is going to be applied there also.

[JC, Koji]

While adjusting the kinematic mount, we noticed that the OMC cable bracket was sagging from the OMC breadboard. This happened with no specific impact given.

This was the delamination of the epoxy (EP30-2) between the glass brackets and the rectangular metal shims. (Attachments)
There was no real damage to the components.

Also, a small delamination area was found on one of the mass mounting brackets (not pictured).

# This OMC was the first manufactured OMC in 2013, installed at LLO, and taken out last year. This is not the unit to be (possibly) used at Hanford.

The EP30-2 of this era had no established procedure for proper mixing yet. We've experienced frequent delamination in the OMCs and suspension assemblies.

Now that procedures for testing epoxy mixtures in a toaster oven have been established, the frequency of such delamination has decreased.

My assessment for the repair procedure:
- Remove the remaining epoxy layer on the glass side by scrubbing with a cotton swab using acetone.
- Apply EP30-2 on the cable bracket.
- Inject EP30-2 mixture to the mass mounting bracket via capillary action.

Strictly speaking, this OMC is a loan from aLIGO, so I will contact the aLIGO team to see if they have no objections to the repair before we start the work.
In the meantime, we can prepare optics for locking the OMC.

Ed (Oct 30, 2023 8AM): The rework was approved by GariLynn and Gabriele.

[JC, Koji]

Integration of the BHD platform and an OMC

- Working environment: The BHD platform was placed on the optical table, and the parts and tools were placed on a wagon. (Attachment 1)

- The OMC used: OMC #1 (used OMC taken out from LLO)

- Cleanliness: HEPA booth / Particle counter borrowed from the PSL table. 0~20 count per cubic foot for 0.5um.

- OMC mounting scheme: The kinematic mount with three balls and three grooves is supposed to fix the position of the OMC once it is aligned. 

- OMC mounting procedure: Firstly, the upper parts were fixed to the OMC  (Attachment 2), while the lower parts were placed on the BHD Platform without fixing  (Attachment 3). Then, the OMC was placed on top. By jiggling the bottom parts, the grooves were aligned to the given ball positions (Attachment 4). Because the lower parts have grooves, they still can move before they are fixed keeping the tangent of the grooves and the balls. After the lower parts were aligned with the fixing thread holes well within the through holes, the hexagonal bolts were fastened with a spanner.

Using this OMC, the lower mounting parts for the second OMC slot were also aligned. They will need to be adjusted with the other OMC given later.

It is important to note that when raising or lowering the OMC from the BHD Platform, the fingers should be put on the attachment for the kinematic mounts from the bottom rather than pulling the glass breadboard up by putting the fingers on the glass breadboard.

This is to avoid extension stress on the glass mounting brackets, which can lead to epoxy delamination and/or cracking of the glass parts. Lifting the attachment for the kinematic mounts from below is safe because only compressive forces will be applied to the bonding on the breadboard surface.

 

I checked Solidworks models to see the mass/moment of inertia for the BHD SOS masses.
The mass/MoI calculation includes 2" glass optic. MoIs were given at the center of mass.

== 0.25 inch optic / original sleeve ==

- Mass = 185 grams
- Moment of Inertia (grams mm^2)
Lxx = 9.84e4 (Pitch)
Lyy = 9.14e4 (Yaw)
Lzz = 1.74e5 (Roll)

== 0.5 inch optic / thick optic sleeve ==

- Mass = 210 grams
- Moment of Inertia (grams mm^2)
Lxx = 9.37e4 (Pitch)
Lyy = 9.52e4 (Yaw)
Lzz = 1.73e5 (Roll)

== 0.75 inch optic / thick optic sleeve ==

- Mass = 235 grams
- Moment of Inertia (grams mm^2)
Lxx = 9.85e4 (Pitch)
Lyy = 1.00e5 (Yaw)
Lzz = 1.80e5 (Roll)

== Ref: 3" x 1" glass optic ==

- Mass = 255 grams
- Moment of Inertia (grams mm^2)
Lxx = 1.06e5 (Pitch)
Lyy = 1.06e5 (Yaw)
Lzz = 1.85e5 (Roll)

I could not find the model for the 3/8" thick optic. The original metal sleeve was designed for 1/4" optic. It is probably possible to put the 3/8" optic into it (with significant misalignment).
It seems that PR2 was installed on Jan 27, 2022. However, both the photograph record and elogs were not detailed enough to identify which metal sleeve was used for PR2.
We need to look into the viewport to identify it.

To fit the 3/8" optic into the thick optic (3/4") sleeve, 3/16" thick ring spacers were required. I have no record of making such sleeves.

The new PR2 optic has a thickness of 1/2". The Solidworks model has the version with 1/2" optic, which was fit into the thick optic sleeve with two 1/8" spacers.
We made a total of 4 thick sleeves. Even if the current PR2 has the original metal sleeve, we are supposed to have one more of the thick sleeves. We still have to find/manufacture Qty 2 of the 1/8" spacers.

EP30-2 kit brought from Downs on Oct 27, 2023. Stephen said he would take care of the property (location) record.

Also, Stephen mentioned that he left the gluing kit in the clean room next to the bake lab. I went there and found the box. It only has two bottles of silica bead powder.

Beam spot position measurements were done again using updated demodulation method.
The measurements now also includes statistical uncertainty (Note that uncertanties below do not include uncertainties in actuation, moment of inertia, and coil balancing).

Results:

# Optic    LSCDoF     freq.(Hz)    ampl. (counts)    gpstime    Opt. gain (counts/nm)    Opt. gain_std    v (mm)    v_std    h (mm)    h_std
ETMY    YARM    211.11    100    1382518790    3764.95    176.42    -0.23    0.11    0.61    0.05
ITMY    YARM    211.11    100    1382518963    3555.57    89.67    -0.13    0.04    -0.26    0.03
ETMX    XARM    211.11    100    1382519267    1295.22    17.97    -0.35    0.20    -0.98    0.18
ITMX    XARM    211.11    100    1382519351    1456.79    36.07    0.24    0.03    0.47    0.07
BS      MICH    211.11    3000    1382519739    1.60    0.10    1.81    0.68    -2.20    0.40
PRM     PRY    309.21    300    1382520366    256.02    12.97    -7.36    1.21    2.74    1.13
PR2     PRY    309.21    300    1382520438    366.31    24.85    -4.84    0.86    -0.33    0.11
PR3     PRY    309.21    300    1382520585    314.60    13.66    0.62    0.96    -13.57    2.67
LO1     HPC    113.13    1000    1382520845    3.78    0.08    5.19    0.20    3.92    0.11
LO2     HPC    113.13    1000    1382520919    3.76    0.12    -12.98    0.99    18.44    0.70
AS1     HPC    113.13    1000    1382520990    4.07    0.08    0.49    0.12    10.84    0.38
AS4     HPC    113.13    1000    1382521061    4.13    0.10    -3.65    0.14    9.28    0.36
SR2     HPC    113.13    1000    1382521135    4.04    0.07    0.07    0.12    5.30    0.51

See attachment for example spectra during the dither for BS.

What we did:
 - Instead of

I=2*np.average(data*sin)
Q=2*np.average(data*cos)
amplitude=np.sqrt(I**2+Q**2)
phase=np.rad2deg(np.arctan2(Q,I))

for demodulating, the following code was used.

Wn=0.0001    # Butterworth filter cutoff will be fs*Wn = 1.6834 Hz for fs=2**14 Hz
[bbb, aaa] = sg.butter(4, Wn)
I = 2*sg.filtfilt(bbb, aaa, data*sin)
Q = 2*sg.filtfilt(bbb, aaa, data*cos)
mask=int(1/Wn)    # remove first part during LPF time constant in averaging
(amp_avg,ph_avg)=(np.average(amplitude[mask:]),np.average(phase[mask:]))
(amp_std,ph_std)=(np.std(amplitude[mask:]),np.std(phase[mask:]))

 - 4th order Butterworth LPF filter with cutoff of 1.6834 Hz was used, and the averaging was done afterwards. Uncertainty was estimated using the standard deviation of LPF-ed data. The first part of data was removed for estimating the average and uncertainty, to wait for the LPF effect to settle down.

/opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureBeamSpotPosition.py

Next:
 - Get moment of intertia for BHD compound optics from CAD.
 - Automate the lock part so that we can run often
 - Check clipping by measuring the power change at each port while dithering.

Beam spot position measurements were done again with the correct sign on the mis-centering.
The sign tells you the sign of A2L when you dither in angle, with respect to the sign of your length dither. It does not tell you if the beam spot is on left/right or upper/lower, but it keeps track of which direction the beam is mis-centered.

Results:

# Optic LSCDoF  freq. (Hz)   ampl. (counts) gpstime Opt. gain (counts/m) v (mm)   h (mm)
ETMY    YARM    211.11    100    1382471007    3.58e+12    0.17    0.12
ITMY    YARM    211.11    100    1382471069    3.48e+12    -0.02    0.06
ETMX    XARM    211.11    100    1382471097    1.27e+12    -0.60    0.15
ITMX    XARM    211.11    100    1382471162    1.44e+12    0.36    0.66
BS      MICH    211.11    3000    1382471289    1.61e+09    2.00    -2.11
ITMY    MICH    211.11    3000    1382471345    1.58e+09    -0.40    -0.88
ITMX    MICH    211.11    3000    1382471405    1.58e+09    0.68    0.57
PRM    PRY    309.21    300    1382487717    2.94e+11    -7.00    2.06
PR2    PRY    309.21    300    1382487787    4.41e+11    -4.41    -0.41
PR3    PRY    309.21    300    1382487847    3.41e+11    -0.70    12.98
ITMY   PRY    309.21    300    1382487963    3.39e+11    0.10    -0.28
LO1    HPC    113.13    1000    1382488200    3.54e+09    5.05    3.93
LO2    HPC    113.13    1000    1382488279    3.64e+09    -12.48    16.24
AS1    HPC    113.13    1000    1382488340    3.77e+09    -0.72    -10.92
AS4    HPC    113.13    1000    1382488397    3.80e+09    -3.39    9.30
SR2    HPC    113.13    1000    1382488482    3.81e+09    -0.18    -5.77

See attachment for example spectra during the dither for LO1.

What we did:
 - We repeated the measurements in 40m/17925 again, but with the correct sign on the mis-centering.
 - The sign on horizontal and vertical mis-centering was defined by the phase difference in the error signal between position dither and pitch/yaw dither. The phase from the position dither was used as a reference to check the sign of the error signal.
 - In the previous version of the code, demodulation was done using a sin wave generated in the code, but now the script also demodulates the excitation signal, C1:SUS-(optic)_(LSC|ASCPIT|ASCYAW)_EXC, to correctly measure the phase relative to the excitation.
 - The script also now saves the optical gain in BeamSpotPositionMeasurements.txt to keep track of things. Note that, even if the optical gain calibration was off, for example from no notching, it doesn't ruin the beam spot measurements, because we are just measuring the relative length noise difference between the length dither and angular dither.
 - The script now handles different thickness of mirrors (but it does not correctly take into account of compound mirror we have for BHD optics...)
 - The script now do not import math * (I'm just used to pi instead of np.pi).

/opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureBeamSpotPosition.py

Both YARM and XARM ASS work.

Next:
 - Fix demod part of the script to use a low pass filter (I tried scipy.signal.filtfilt, but failed. Probably because the cut off frequency of scipy.signal.butter I used being too low compared with the sampling frequency or something).
 - Get moment of intertia for BHD compound optics from CAD.
 - Check clipping by measuring the power change at each port while dithering.
 - Add uncertainty in the measurements.

I looked at this code and it is a little untrustworthy. The demod is not being done correctly so there can easily be some aliasing going on.

in this lab we really, really should never use a moving average instead of low pass filtering.

And why import math instead of using numpy??

[Begüm, Paco, Yuta]

Beamspot position measurements were done using A2L, assuming all the coils are balanced.
Beam centering on PR3, LO2, AS1, AS4 are off by more than 1 cm.
ITMX centering (which we ignore in XARM ASS) is pretty good.

Results:

# Optic LSCDoF  freq(Hz)   amplitude   gpstime v (mm)   h (mm)
ETMY    YARM    211.11    100.0    1382413915    0.20    -0.20
ITMY    YARM    211.11    100.0    1382413976    -0.01    0.07
ETMX    XARM    211.11    100.0    1382414046    0.08    -0.17
ITMX    XARM    211.11    100.0    1382414280    0.43    0.42
BS      MICH    211.11    1000.0    1382414504    2.00    -2.30
PRM     PRY     309.21    300.0    1382415273    -7.70    -1.85
PR2     PRY     309.21    300.0    1382415349    5.37    0.25
PR3     PRY     309.21    300.0    1382415473    0.85    13.59
ITMY    PRY     309.21    300.0    1382415569    -0.25    0.15
LO1     HPC     113.13    1000.0    1382416132    -5.78    -4.43
LO2     HPC     113.13    1000.0    1382416189    -13.79    18.33
AS1     HPC     113.13    1000.0    1382416253    0.85    12.61
AS4     HPC     113.13    1000.0    1382416315    -4.21    10.65
SR2     HPC     113.13    1000.0    1382416389    -0.38    5.45

Method:
 - Lock some interferometer configuration which involves the optic you want to measure (e.g. PRY for PRM).
 - Put a notch filter at the frequency you want to dither in the LSC loop.
 - Dither C1:SUS-(optic)_LSC_EXC and demodulate the error signal to get the optical gain of the error signal.
 - Dither C1:SUS-(optic)_ASC(PIT|YAW)_EXC and demodulate the error signal. Calibrate the demodulated error signal into meters using the optical gain derived above. Calibrate the optic motion using angular actuation efficiency estimated using the method described below. By dividing the length change by angular motion, you get the mis-centering.
 - This method asumes that there is no clipping, all the coils are balanced, POS/PIT/YAW are purely actuated, and optic center is the same as actuation node.
 - For measuring the beam spot positions on ETMs and ITMs, signle arm locking configurations were used.
 - For measuring the beam spot position on BS, MICH configuration was used.
 - For measuring the beam spot position on PRM, PR2 and PR3, PRY configuration was used.
 - For measuring the beam spot position on LO1, LO2, SR2, AS1, and AS4, ITMY single bounce vs LO configuration was used.
 - Attachment #1 shows the spectra of error signals during dither, showing SNR is pretty good.

/opt/rtcds/caltech/c1/Git/40m/scripts/ASC/measureBeamSpotPosition.py

Estimating angular actuation efficiency:
 - Angular actuation efficiencies were estimated using the following

A_ang = A_lsc * dd * mass / (2*I)

where A_lsc is the length actuator efficiency measured in 40m/17886 and 40m/17918, and

rr = 3*inch/2    # radius of the optic
tt = 1*inch  # thickness (ASSUMPTION!!!; they are random for BHD optics (;x;) (╯°□°)╯︵ ┻━┻)
dd = 1.945*inch # distance between magnets https://dcc.ligo.org/LIGO-D960002
rho = 2.201*g/(cm**3) # density of fused silica (note that BHD optics have 2inch -> 3inch sleeve made of aluminum)
mass = pi*rr**2*tt*rho # mirror mass
I = mass*rr**2/4+mass*tt**2/12 # moment of inertia

 - In summary, they are the following. Note that A_ang is not the physical angle you move, but is what you see by LSC through A2L.

Susp. | LSC meas. nm/count | Gain adj. | AoI deg | POS nm/count | ANG urad/count
BS   +69.54 +2.325 45 +21.15 +4.12
ITMX +14.73 +0.653  0 +22.55 +0.87
ITMY +14.50 +0.659  0 +21.99 +0.86
ETMX +12.20 +0.414  0 +29.47 +0.72
ETMY +10.66 +0.480  0 +22.21 +0.63
MC2  +2.27 +0.105  0 +21.62 +0.13
PRM  -19.00 +0.773  0 -24.58 -1.13
PR2  -36.19 +1.000  0 -18.09 -2.15
PR3  -29.57 +1.000 45 -20.91 -1.75
LO1  +28.25 +1.000  0 +28.25 +1.67
LO2  +11.19 +1.000 45 +15.83 +0.66
AS1  -25.92 +1.000  0 -25.92 -1.54
AS4  +25.82 +1.000  0 +25.82 +1.53
SR2  -16.63 +1.000 45 -23.52 -0.99

Next:
 - Check the sign of mis-centering. It is kind of random now.
 - Put uncertainty in these measurements.
 - Include HPC in the LSC screens

XARM ASS Fixed (hopefully)

The winning approach was considering T and L loops separately, and adjusting the gain hierarchy. After chatting with Rana, we reconfirmed that the centering length (L) loop should feed back to the cavity optics, and the pointing transmission (T) loop should feed back to the BS. We discussed dithering the BS to generate a pointing error signal, but it turned out this wasn't necessary since a solution was found with just dithering the ITM and ETM. I decided to make the T loop fast and the L loop slow, as was done previously by Anchal.

Attachment 1 shows the final servo gains and output matrix, along with the Striptool showing maximized transmission and suppression of error signals.

T loop

The intuition was to use the ITM T signals (transmission demodulated at ITM dither freq) as a proxy for the BS pointing error, as was done previously:

ITM PIT/YAW T --> BS PIT/YAW

Next, ETM T signals were fed back to the ETM to maximize transmission. This has always worked:

ETM PIT/YAW T --> ETM PIT/YAW

The signs were chosen based on what suppressed the error signals.

L loop

On paper I worked through how ITM/ETM misalignment shifts the beam spot on both the ITM and ETM. This was mainly a helpful exercise to gain intuition for the centering. I made small angle assumptions and ended up with:

Here r is the radius of curvature of the ETM (57.37cm); l is the length of the arm cavity (40m); d is the displacement from center of the optic; θ is the angular misalignment of each optic.

In practice, we do not care about the centering of the beam on the ITM. So in reality the useful takeaway was that ETM and ITM angular misalignment both shift the beamspot on the ETM by roughly the same amount.

ETM PIT/YAW L --> ETM PIT/YAW

ETM PIT/YAW L --> ITM PIT/YAW

Again the signs were chosen to suppress the ETM L error signals without the T loop on.

Lastly, I chose the T loop gain 0.1 and L loop gain 0.2.

Instructions for running

The servo gains and output matrix have been updated in ASS_Settings_XARM.snap. Just hit "Run ASS".

[Begüm, Koji]

We brought the OMC #1 / DCPDs / a glass breadboard from the OMC lab to the 40m. They are placed on the wagon next to the staging table.

= BHD Platform assembly on the staging table =

• [Done] The assembly will be (mostly) done by the end of Thu (JC)
• [Done] OMC is going to be mounted on Fri (KA/JC)
   
• After the vent, we will bring out the BHD optic from the ITMY chamber.
   
• We'll continue to work on the BHD platform alignment on the staging table
  with the optics/optic mounts taken out from the chamber.
  + the OFI components (incl. the machines posts)
   
• Asking Dean for the mighty mouse connectors for the devices
  • -> Asked. We need the connectors and pins. Dean is working on the procurement.

= OMC mounting / locking =

• [Done] Bring the OMC#1 from the OMC lab (KA, Thu afternoon)
• [Done] Attach the kinematic mounting brackets on the OMC. 
• Blank OMC breadboard for counterweighting (KA, bring from the OMC lab) -> Brought
   
• Locking electronics 
  • [Done] Paco prepared:
    Moku, PDA10 (150MHz), HV Amp for Laser or OMC PZT
     
  • Prepare locking optics (steering mirrors, post, etc)
     
• OMC DCPD prep
  • [Done] Bring the DCPDs (Excelitas C30655) from the OMC lab
  • Remove the cap of the diodes (Asked Dean about the tool)
  • DCPD installation on the OMCs

= IFO work until the vent =

• [Done] X arm ASS repair (Radhika)
• FPMI / PRMI locking
  • BS is moving a lot -> fix

= Vent Prep =

• [Done] Watchdog implementation on all the optics
• Clipping investigation

= Vent =

• Table tilt check (digital tilt meter)
   
• Open ITMY:
  • pick up components for BHD platform
  • Turn SRM
  • BHD platform installation
  • Counter weight adjustment
     
• Open ITMX:
  • PR2 sus optic swap -> optic thickness 3/8" -> 1/2", needs adjustment
• Open BS / INJ
  • Clipping check
     
• Vacuum maintenance
  • Remove TP1 for maintenance
  • TP2 communication error problem

Wiring configuration for the picomotors and the HWP rotator.
The mighty mouse connectors on the devices are supposed to mate with the cable D2300210.
I'm asking Dean to help us for the mighty mouse connectors.

I drew a block diagram to work through the high-bandwidth CARM feedback using the CM board. The goal was to obtain a derivation for the loop algebra used in CM board YARM locking here, applied to CARM locking. Attachment 1 is the diagram with the following blocks:

Below are the independent, decoupled OLTF expressions for each loop (other loops off):

1. G_IMC is the OLTF of the IMC-->PSL loop (middle loop in diagram):

2. G_LSC is the OLTF of the slow LSC loop (bottom loop in diagram):

3. G_CMB is the OLTF of the fast CM board loop (top loop in diagram):

Now that the independent loop OLTFs are defined, we can interpret the loops that have been measured:

1. The LSC slow CARM loop is always measured with the IMC locked, so the measured TF will include the IMC loop supression:

2. The CMB TF measurement is taken with the IMC locked and the slow LSC loop enabled (all 3 loop on). The measured TF will include IMC loop supression and suppression from the LSC loop, which is further suppressed by the IMC loop. The expression below is what you obtain when calculating i1/i2 in Attachment 1 (see derivation in Attachment 2):

Note that the final expression is in terms of known or measured quantitites. 

[JC]

I came in this morning and began to fiddle with the Spectrogram. There was an error with the previous code and it doesn't have the ability to open anymore. After sometime of trying to fix the issue of the code, I ooked up and realized that IMC was not aligned. I checked WFS and the screen was frozen. After 10 min or so of searching, I realized the cds screen I was looking at was one from yesterday (it was frozen). After opening a new CDS screen, I noticed c1sus2 crashed again.

When using this Fencing technique on c1sus2, I haven't been able to avoid tohe issue of DK triggering on c1x04, and c1x01. Although, when I use the technique on C1LSC and C1ISCEX, it works perfectly fine. I may be doing this incorrectly though. Her are the steps I took this morning. Please let me know if I did something incorrectly.

1. SSH into fb1 and run the following command " ./dolphin_ix_port_control.sh --disable 192.168.113.40 6 "
2. ssh into c1sus and run "sudo reboot" This will return you back to fb1.
3. ping c1sus2 until the machine stops responding.
4. Once the machine stops responding, enable the dolphin port by running " ./dolphin_ix_port_control.sh --enable 192.168.113.40 6 "    This is done before the machine boots back up.

After I did this, DK trigger on onc1x04, and c1x01. I repeated the steps for both C1LSC and C1ISCEX and burtrestored the machines to yesterday at 17:19. After this, our system was brought back up to its original state before the c1sus2 crash.

[Begüm, Vittoria, Yuta]

We calibrated actuators for BHD optics under PRY and ITMY-LO fringe configurations using ITMY as a reference.

Method:
 - For calibration PR2 and PR3, we locked PRY using REFL55_I as an error signal and PRM as an actuator. We measured transfer functions from C1:LSC-ITMY_IN2 or C1:SUS-(PR2|PR3)_LSC_IN2 to C1:LSC-REFL11_I_ERR. Took the ratio of TFs with respect to ITMY (measured in 40m/17886) to calibrate PR2 and PR3 (Attachment #1 and #2).
 - For calibration of LO1, LO2, AS1, AS4, SR2, we locked ITMY single bounce vs LO fringe using BH55_Q as an error signal and BS as an actuator. We measured transfer functions from C1:LSC-ITMY_IN2 or C1:SUS-(XXX)_LSC_IN2 to C1:LSC-BH55_Q_ERR. Took the ratio of TFs with respect to ITMY to calibrate them (Attachment #3 and #4).

Summary of results:
 - Summarized in the floowing table. Results are in the unit of /f^2 nm/counts. If you divide the raw measurement (labeled Meas. nm/count) by "V2A" filters used for gain adjustments and are compensated by AoI or BS to MICH (factor of sqrt(2)) or PR2/3 to PRY (factor of 2), they are all in the range of 18-30 /f^2 nm/counts. LO2 have small actuation efficiency which was known because of too much pitch alignment offset. LO1, LO2, AS1, AS4 were calibrated before in 40m/17285, and the new measurements are consistent. PR2, PR3, SR2 calibration were done for the first time.

Susp. | Meas. nm/count | Gain adj. | AoI deg | nm/count
BS   +69.54 +2.325 45 +21.15
ITMX +14.73 +0.653  0 +22.55
ITMY +14.50 +0.659  0 +21.99
ETMX +12.20 +0.414  0 +29.47
ETMY +10.66 +0.480  0 +22.21
MC2  +2.27 +0.105  0 +21.62
PRM  -19.00 +0.773  0 -24.58
PR2  -36.19 +1.000  0 -18.09
PR3  -29.57 +1.000 45 -20.91
LO1  +28.25 +1.000  0 +28.25
LO2  +11.19 +1.000 45 +15.83
AS1  -25.92 +1.000  0 -25.92
AS4  +25.82 +1.000  0 +25.82
SR2  -16.63 +1.000 45 -23.52

Next:
 - Use these actuation efficiencies to dither each optic and see beam spot positions on them

While locking ITMY single bounce vs LO fringe, c1sus2 crashed again (at around 17:20 local).
c1sus2 rebooted with Dolphin thing, but it crashed c1lsc, c1sus, c1iscex, so we also had to reboot these machines.
Burt-restored all by /opt/rtcds/caltech/c1/Git/40m/scripts/cds/burtRestoreAndResetSUS.sh /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2023/Oct/24/16:19

[paco, yuta]

We achieved a ~23 kHz CARM bandwidth this evening when locking FPMI using the CM Board.

Configuration:

• REFL55_Q_MON to IN1 of CM Board.
  • The REFL55 RFPD demod angle is conveniently 92 deg, so REFL55_I (CARM error point) = REFL55_Q_MON
• AO to MC Servo Board
• Moku:Pro Freq response analyzer used to measure the CM Board loop
  •  TP1 (CMB) to IN1 (Moku) and TP2 to IN2 points around the first OUT2 (Moku) to EXC (CMB).
• The gain sliders we used were REFL1 Gain (+23 dB) and AO Gain (max +18 dB before we see loop oscillations).
• No Boost could be enabled, regardless of the polarity.
• Apparently both polarities were good for this lock (why?)

See Attachment #1 for the MEDM screenshot.

Results:

The inferred CARM UGF is ~ 23 kHz, as can be seen from Attachment #2 and using the loop algebra described in (40m/17628). Instead of the definition in 40m/17628, we plotted the following for the inferred CARM HBW loop OLTF (with all the other loops off).

G_CARM = G_IMC / O_IMC * O_YARM * C_YARM * F_CMB = r * G_IMC * C_YARM * F_CMB

Now the OLTF of CARM loop measured at CARM Common Mode Board with all the loops on can be calculated as

G_meas = G_CARM / (1 + G_IMC) / (1 + G_LSC/(1 + G_IMC) )

where G_LSC/(1 + G_IMC) is the OLTF for CARM digital LSC loop, with IMC loop on, which is usual CARM LSC OLTF we measure digitally.
(ORANGE texts added by YM on Oct 25 at 17:40 to update G_CARM definition to clarify; see 40m/17920 for loop algebra)

Attachment #3 shows the calibrated DARM readout with and without the CM Board feedback enabled. We can only assert the noise dropped slightly around 50-100 Hz, but not a lot (which is good in a sense).

Next:

• Check BOOST and Polarity, maybe incorporate an independently measured BOOST transfer function into the model to understand better. 

Thanks, JC for putting the parts together! I'll start collecting the instruments necessary for the OMC mounting / locking.

[Vittoria, Yuta]

We restored the alignment after c1sus2 crash (40m/17911).
Both FPMI and PRMI sensitivities look consistent with the recent measurements.

What we did:
 - Realigned PMC to get C1:PSL-PMC_PMCTRANSPD of 0.68
 - Realigned IMC to get C1:IOO-MC_TRANS_SUMFILT_OUTPUT of 12900-ish (might be able to tune more)
 - Realigned YARM and XARM. Both arms were not flashing when we started. ITMY OSEM was stuck and YAW kick was applied to unstack. All the related suspensions required quite a bit of alignment tuning especially in pitch.
 - Locked FPMI with REFL55 and AS55, and measured the sensitivity (Attachment #1)
 - Locked PRMI in carrier, and measured the sensitivity (Attachment #2)
 - Resulting alignment is in Attachment #3

Next:
 - Stabilize PRMI lock.
 - Measure actuator efficiencies of PR2, PR3, SR2, AS1, AS4, LO1, LO2, and roughly estimate angular actuator efficiencies for all the suspensions.
 - Dither each suspension during PRY, PRX, SRX, SRY locks to see beam spot positions on vertex suspensions to check clipping to prepare for vent.

There should be a correct wrapper script such that we don't need to do nonsense like remembering the IP address and the port number.
The timing of disabling and enabling is important too...

Today, I spent majority of my time insterting the Helicoils for the Platform Assembly, D2100435. 181 Inserts to be exact. and I also got around to setting up the build for up the D2200400, 405, and 406. I expect for the assembling of the BHD platform to be maxed by Friday. (Maxed as in we need to pull parts from which are currently in Vacuum). I want OMC to be added on Friday and for us to begin the following week with alignment of the BHD Assembly.

Tasks which still need to be done

• Assembly of D2200400, 405, and 406.
• Bring over OMC and install onto the platform.
• Alignment of the BHD and OMC.
• Optic-Fibre input to the cleanroom.

We used this technique earlier and we came across a mistake while we were following the steps from the elog. (The Wiki is better, here : https://wiki-40m.ligo.caltech.edu/CDS/DolphinSwitch)

When inserting the IP Address for Steps 1 and 4, you must denote the correct machine by its assigned number from Wiki.

./dolphin_ix_port_control.sh --disable 192.168.113.40 # 

Yuta and I made this mistake, used the IP Address of C1SUS2, and DK turned on for c1x04, c1x02, and c1x03.

The systen was brought back up using the technique correctly and all systems were burtRestored to Oct/23/00:19

The BHD platform assembly is going well. I have gotten majority of the Helicoils into all of their components. The only Helicoils I have left to insert are those of the breadboard. I have finished assembling 4 of the D220392, and 2 of the D2200409. Next I will be inserting the HeliCoils into the breadboard and working on D200400, D200405, and D200406. If lucky, I will also be able to tackle the Optic Mount Assemblies D2100200 and 2100435 on Monday afternoon as well.

I've attached a photo of the finished components.

[Paco, yuta]

We investigated the situation of the CM board again this morning. We measured the transfer function from IN1/IN2 to TPs/AO and changed the configuration around every time. We noticed slider gains such as REFL1 Gain / REFL2 Gain / AO Gain / SUPER BOOST had absolutely no effect but binary switches such as BOOST / OPTION / G=1, z=1.6 kHz, p=79Hz were working correctly. We also noticed the bit word at the bottom right corner of some sliders was always 0x0, in contrast with the MC Servo IN2 Gain which at -32 dB indicated 0xffe0. This made us look into the modbus related files in c1iscaux under /cvs/cds/caltech/target/c1iscaux where we discovered the latch.py script. After browsing the elog and wiki a little more, we realized there is a logic implemented in this slow channels to prevent sudden gain switchings, but we still don't fully understand how it is running or where? What we did find was that somehow c1iscaux was running a python script (latch.py?), and according to top it has been running for a little over 79 hours (but where/why/how?).

After killing the python3 processes in c1iscaux, we recovered the CM board slider functionality (but why?) and verified the transfer functions are getting the right gains. We also checked the Offset (V) and noted that when sliding to +-10 Volts the resulting offset was +-95 mV. I confirmed through the schematic (+ Koji) that the +- 10 V bias from the slow DAC is reduced by the trim circuit shown in Attachment #1 so this is also working properly. To reflect this, I updated the medm screen to mimic what is done in the MC servo board screen (includes the division from the raw DAC offset to the summing junction in the signal chain), see the result in Attachment #2.

Basic Arm Alignment has been done

• WFS seemed to have railed overnight.
  • The first action I took this mornign was to turn wfs off. Once I saw that I holding well, I ran the 60s WFS Relief script.
• I align the single arms, C1:LSC-TRY_OUT_DQ transmission to ~1.0 and C1:LSC-TRX_OUT_DQ ~ .8

I'm going to continue working on the BHD platform now.

The first assemblies I am working on are D2200406, D2200154,and D2200392.

[Paco, yuta]

FPMI

- We recovered the FPMI lock after aligning YARM, XARM and MICH. For this, the TT1,TT2 PITCH were adjusted quite a bit, but the arm cavity transmission was steady and close to 100%. 

- MICH seemed slightly unstable, so we checked a few things. (1) The noise spectrum showed excess noise around 300 Hz with a forest of high frequency peaks around  seemingly spaced by a constant ~ 9.8 Hz. Reducing the DARM loop gain from 0.044 to 0.030 (UGF reduced from 200 t0 150 Hz) helped in lowering the overall 300 Hz noise (Attachment #1), but the 9.8 Hz peaks remained (Attachment #2). (2) The MICH UGF was 30 Hz, as expected. Furthermore, we noted the IR transmission in both arms was coherent with the AS55_I_ERR signal when FPMI was locked (Attachment #3).

- To try and improve our MICH situation, we tried disabling the BS OPLEV loops but this didn't have an effect. We also tuned  the demod phases for REFL55 and AS55 RFPDs. The changes were made to minimize the CARM content in both signals:
    REFL55 from 96.22 to 94.13
    AS55 from -166.00 to -159.77
which didn't seem to help this issue but made our lock acquisition better.

This issue remained for tonight, and we decided to move on to investigating the CM Board situation.

CM Board

- The expectation is to achieve "mid-BW" CARM loop of a few kHz to couple of 10 kHz with FPMI. This is because the CM board is modified to match the PRFPMI CARM pole (~200 Hz) and is not expected to be stable for a "high-BW" single ARM pole (~4 kHz) at its highest gain configuration. So the goal is to recover the mid-BW ARM/CARM lock (see 40m/17628 for what we did last time in June 2023).

- We first locked YARM using POY11_I_ERR (UGF ~ 200 Hz) and then connected the POY11_I_MON signal from the IQ demod board to the IN1 of the CM board. 
- We decided to also connect REFL55_Q_MON to IN2 (note that because of the ~ 90 deg demod angle above, REFL55_Q_MON conveniently carries the equivalent to REFL55_I_ERR used as the CARM error point). 
- We hooked up the moku pro to TP1, TP2 and (enabled) EXC ports at the first stage and enabled the AO output to MC Board IN2 (which was disconnected for some reason)
- We added input gain to the IN1 (YARM) but didn't really break the lock even when we expected it to break (>+30 dB, >0 dB), so we suspected something was wrong with the board.

- After connecting two test points to a scope, we moved the REFL1_IN_GAIN slider around but couldn't see an effect on the TP1 signal... The boost, polarity and offset seemed to work (although applying a 3 Volt offset had the effect of ~30 mV offset at the scope). 

We suspect the CM board is not working appropriately, so we will continue debugging it tomorrow. 

!!We Now Have WiFi Through The Entire Lab!!

Paco and I connected the new routers and expanded the wifi network throughout the lab. These are connected in a "bridge" type of way so that our WiFi doesn't disconnect when we reach the ends. I have also added labels along the ethernet cable to make it easy for us to follow if we run into any issues later on. The Ethernet cable which runs down the Y-Arm is Red and the Ethernet cable which runs down the X-Arm is Blue. The router for the Y- Arm is located on top of the 1Y4 Rack and the X-Arm router is located on the

[Murtaza, Paco, Radhika]

We got some LT1128s from downs (Dean) to get this board up and running again. We first did a test replacement on Ch2 (since Ch1 was working) and got the desired transfer function (z=1, p=[10, 1000]) measured up to the test point. We ended up replacing a total of 5 ICs, all 1128s, and the board seems fine now. See Attachments #1-2 showing which ICs we replaced and a snap of the TF measured using 100 mV of source amplitude to avoid saturation.

Wed Oct 18 15:26:38 2023 Updated the dcc entry reflecting these changes

Installation

Attachment 3 shows the original state, plus the unconnected whitening board installed to the right of the oplev board. Here the oplev board output ribbon cable was sent directly to the AA chassis input 21-24. We then routed the oplev monitors to the whitening board (via 1-->2 pin LEMO cables) and send the whitening board output to the AA chassis input 21-24 [Attachment 4]. We verified the board was drawing current; this concluded the install.

[JC]

I was able to make a spectrogram of Mc Frequency noise using the gwpy package in Jupyter. The channel I grabbed data from was C1:IOO-MC_FREQ_OUT16 because the code didn't seem to like "C1:IOO-MC_FREQ_OUT" very much.

Anyways, I was running into the issue of plotting the spectrogram using TimeSeries.get(~~~~) in mycode. The error i was getting was "TimeSeries has no attibute" It turned out that I was using the wrong plotting function. The correct way was the use the xyz.plot(norm='log', vmin=MinValue, vmax=MaxValue) with 'xyz' being the name you assigned to you spectrogram data. The graph looked odd to me at first, but it turned out that I was using the PSD, so after Sqrt-ing it,  the plot looked a ton of a lot better.

As of now, this code is on Rossa. So next, I have to work on getting this on the big screen in the control room and passively updating every 5 minutes. This means getting the CDS environment CORRECTLY installed correctly on Stella.

Please keep in mind that this is not finished. Proper labels and cooler axes will be added. This is just what I have going as of now.

I resumed work to restore XARM ASS

I manually aligned XARM and calculated the output matrix using scripts/ASS/getASSOutMat.py. This script gives an offset to the ETM/ITM/BS in pitch and yaw and records all error signals to construct a sensing matrix (8 err signals x 6 actuators). Then the ITMX PIT/YAW L error signal rows are removed (as per XASS historical practice) and the resulting square matrix is inverted.

A few times I loaded the output matrix and turned up the ASS servo gain, but this caused error signals to diverge and transmission to drop. I realigned XARM in between each time and recalcuated the output matrix until one looked promising [Attachment 1].

- From a decently aligned state, the servo maintained transmission and controlled error signals began to converge to 0.

- However when I gave an offset to some optic, transmission started to recover but then dropped even as all controlled error signals were minimized [Attachment 2]. A zoomed version of this is in Attachment 3.

     - ITMX PIT L (light blue) / ITMX YAW L (light pink) are uncontrolled

     - ETMX PIT L (dark blue) has a ~0.2 Hz oscillation, but its mean error is roughly 0. This behavior has been present since XASS stopped working, but it is yet to be understood.

The output matrix is successfully reducing the error signals it controls, but transmission is not maximized. I wonder if it's stuck in a local minimum, but I haven't convinced myself that these error signals can be 0 when the beam spots aren't centeredand cavity/beam axes aren't matched. Maybe we need to use the ITMX PIT/YAW L error signals.

Things to try:

1. Assume pitch and yaw are decoupled and calculate a checkerboard output matrix, and debug each angular DOF at a time. I briefly did this today and got the pitch loop to increase transmission, but not the yaw loop.

2. Altering the sensing matrix to include ITMX PIT/YAW L error signals. Then I'll use the same script to compute the output matrix.

Since the MC_TRANS_PIT and MC_TRANS_YAW control signals were still small even though the sum was ok, I found the C1:IOO-MC_TRANS_PIT/YAW FM5 error point filter which was a +80 dB compensation of the -80 dB C1:IOO-MC2_TRANS_PIT/YAW servo filter was off. This is probably a result of poorly updated snap files so burt missed it after recent model restarts. I will keep an eye on the WFS in the short-term. Attachments #1-3 show the relevant filter locations.

PRMI 1f carrier locking using AS55_Q and REFL55_I was recovered, but only stays for ~30 sec so far.

Configuration changes:
 - C1:LSC-PRCL_GAIN was increased to -0.011 from -0.0054 to compensate for PRM actuation decrease by half (40m/17886).
 - MICH actuator was changed to 0.5*BS - 0.915*PRM from 0.5*BS - 0.307*PRM to compensate for BS and PRM actuation changes (40m/17886).
 - These updated parameters are saved in /opt/rtcds/caltech/c1/Git/40m/scripts/LSC/PRMI-AS55_REFL11.yml

Results:
 - These changes gave PRCL UGF of ~200 Hz (Attachment #1), which is consistent with past measurements (40m/17696).
 - MICH UGF was ~150 Hz (Attachment #2), which is three times higher than past measurements (40m/17696). BS actuation was changed only by about 40%, som I'm not sure why.
 - C1:LSC-POPDC_OUT is about 1500-1700, when maximum. It fluctuates a lot (Attachment #3), and lock is stable only for 30 seconds or so.
 - PRCL sensitivity looks almost the same as what we measured in August, but has some excess noise above ~70 Hz (Attachment #4).
 - MICH sensitivity looks almost the same as what we measured in August (Attachment #5).
 - Current IFO alignment is shown in Attachment #6.

Next:
 - BS damping loops look strange. Too much coupling betwen DoFs. Input matrix needs to be investiaged.
 - Recover PRMI 3f

The last N2 tank ran out this morning ~3:00am. Since then the Vac system tripped and the shutter closed. I had to head over to the shipping dock and pick up a tank myself, but the system is back up and I am now aligning. I've attached the nominal Vacuum state below. This is what we want to be at whenever bringing the vacuum system back up.     

[Yuta, Paco, Murtaza]

[WIP]

Chasing the excess noise in TRX, Yuta suspected the whitening-dewhitening situation for the ETMX.
We compared the OPLEV spectrum for the IFO optics to gauge the situation. The spectrum with dewhitening filters (p = 1Hz, z = 10Hz) (FM3, FM4) 
-Active for all optics (Attachment 1)
-Deactive for ETMX (Atachment 2)

Attachment 1: ETMX >1Hz shows the extra dewhitening filter applied which concludes a misisng analog whitening filter (which it is supposed compensate for)

We compared the X-end with the Y-end rack and found the whitening board for ETMX OPLEVs missing (Pentek Generic Input Board).
We found the board but could not determine the reason for the missing board in previous elogs.

We proceeded to check the board for potential damage. To do this, we we evaluated the transfer functions the filters.

- The board schematic does nott exist on D020432 anymore and is moved to D1500270 (The label on the board says D020432)
- The schematic does not record the modified values for the resistors and capcacitors to place the pole-zero pair at 1, 10Hz
[INSERT NEW VALUES]
- The transfer functions were evaluated using a swept sine measurement from the {input}-> {1st header, 2nd header, tie point} (for example, {J3} -> {J1, J2, T1}) for the first 4 filters (which had existing connections) (Attachemnt 6)
- A good transfer function ( Attachment 3)  is expected with the filter design was obtained on a few ports ✓; others looked garbage (Attachment 4) ❌
- Attachment 5 shows the good/bad outputs

Summary of QPD filter whitening situations:
 - ETMX and ETMY oplevs have whitening (not now for ETMX) of two 10:1 (D020432, which is actually D1500270)
 - TRX and TRY QPDs have whitening of two 40:4 (D1400415, D1400414)
 - ITMX and ITMY oplevs have whitening of two 10:1 (D020432, which is actually D1500270)
 - BS, PRM, SRM oplevs and MC2 TRANS QPD do not have whitening
 - They are always on and compensated with digital anti-whitening filters (not now for ETMX; for now, ETMX digital anti-whitening filters are turned off to have better oplev damping).

ALS DARM and CARM locked.
The procedure basically follows what have already been done in 40m/17764 (YARM IR to ALS), 40m/17768 (XARM IR to ALS), and 40m/17819 (CARM IR to ALS).

Procedure:
 - Lock electronic DARM and CARM using POX11_I and POY11_I as we do everyday.
 - Lock both Y and X green.
 - Setup DFD, reset phase tracker phases, as we do everyday.
 - Measure relative gains, including signs, between C1:LSC-ALSY_OUT and C1:LSC-POY11_I_ERR, C1:LSC-ALSX_OUT and C1:LSC-POX11_I_ERR by dithering CARM at 13.3 Hz.
 - Balance them using measured relative gains. (balanceChannels.py)
 - Remove offsets from C1:LSC-ALSY_OUT and C1:LSC-ALSX_OUT using C1:LSC-ALS*_OFFSET. (putAvg.py)
 - Slightly reduce gains (probably not so necessary, but will create more phase margin)
    C1:LSC-DARM_GAIN: 0.044 to 0.04
    C1:LSC-CARM_GAIN: 0.011 to 0.008 
 - Hand off from POX11_I +/- POY11_I to ALSX +/- ALSY.

Results:
  - The time series of the last two steps are shown in Attachment #1. 
    At -30s-ish, CARM was handed off (POX and POY noisier)
    At -20s-ish, DARM was handed off (POX and POY further noisier)
    At -5s-ish, DARM and CARM offsets where added.
 - The procedure is fully automated, and the configuration file live in:
 /opt/rtcds/caltech/c1/Git/40m/scripts/LSC/ALS-CARMDARM.yml 
 - DARM sensitivity with DARM locked with ALS DIFF is shown as magenta line in Attachment #2. Compared with IR RF lock in blue, it is noisier above 30 Hz.
 - Using POX11_I as an out-of-loop sensor, residual DARM RMS is about 0.9e-10 m.

Next:
 - Fix ETMX oplev QPD whitening situation
 - Try ALS assisted FPMI
 - Restore PRMI 1f 3f locking
 - Lock PRFPMI

[Paco, Yuta]

Attachment #1 shows tonights OOL ALS noises with the PSL hepa OFF, and arm cavities locked using POX/POY.

This evening during an FPMI lock stretch we took transfer functions from C1:LSC-DARM_IN2 to C1:ALS-BEATXY_FINE_PHASE_OUT (the individual ALS beat sensing points) to reproduce the measurement described by Anchal in (40m/17562) and also reported in his thesis. The diaggui template for this measurement was saved under /users/Templates/ALS/BEATXY_DARM_TF.xml

Anyways the residual frequency dependence shown in Attachment #2 and seems less dramatic as previously described, amounting to <10% over the DFD + phase tracker bandwidth (2kHz) and with a low excitation SNR (~ 2). According to our previous estimate there was > 100% across the same frequency band.

Wait, what?

Recently, we straightened DW switching on ETMY (40m/17875) so the DARM actuation is definitely homogeneous because both ETMY and ETMX are in the same (acquisition) mode. Before ETMY had a weird mix of DW switches. Another possibility is that the previous measurement excited only the YARM length (actuating on ETMY) thus creating a CARM as well as DARM signal which was seen by the ALS beat. This seems like a perfect recipe for confusion.

Hence I will  focus on high bandwidth CARM locking in the context of PRFPMI locking for BHD, and stop this Hi-BW CARM for calibration witch hunt.

[Murtaza, Vittoria, Paco, Yuta]

We restored FPMI RF locking for the first time after the vertex coil driver upgrade.
RF demodulation angles changed a quite bit.
We observed excess noise in YARM, XARM single arm configurations, but not in FPMI.

YARM and MC_F noise measurements:
 - The noise spectra were taken when YARM is locked with POY11 using ETMY as an actuator.
 - Compared with the noise spectra taken in August 2023 (dashed lines; 40m/17766) before the upgrade, YARM noise has excess noise around 40-300 Hz, and MC_F has some excess noise around 40Hz (Attachment #1).
 - 60 Hz noise peak in MC_F seems nominal, but in YARM it is about an order of magnitude larger (Attachment #2; it should be about 10 Hz/rtHz or 1.4e-12 m/rtHz with bandwidth of 0.187493 Hz; see 40m/17461). This is not as bad as misconfigured MC1 and MC3 dewhitening; it used to give two orders of magnitude increase at 60 Hz.
 - 60 Hz noise peak in YARM could be because of lack of analog 28 Hz ELP now (see 40m/17466). Turning on/off digital 28 Hz ELP filters in MC1 and MC2 coil outputs didn't change the situation. Turning on/off IMC WFS also didn't change the excess noise.
 - Excess noise in YARM could be from vertex coil driver upgrade.
 - We don't see clear excess noise around 1 Hz, so suspension dampings are probably not so bad.

XARM:
 - The same story for XARM (Attachment #3 and #4). Now the dashed lines are from August 2022, even before the ETMX coil driver upgrade (happened in June 2023)

IFO alignment:
 - BHDC_A and B seems to be degraded from their nominal values of ~34 to ~27 (see below and 40m/17671). We might need to play with TT1/2 and PR2/3 to do YARM alignment. Or may be LO alignment is not compatible with PRC alignment.
 - TRX also fluctuates too much compared with TRY. This seems to be coming from ETMX motion (see Attachment #5). This was taken at around 4pm, but it will be much better in the night (Attachment #10).

>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 0.6865958929061889 0.0007320942064261143
C1:IOO-MC_TRANS_SUMFILT_OUT 13215.416015625 22.983493891497357
C1:LSC-TRY_OUT_DQ 1.0542557954788208 0.012796686190180762
C1:HPC-BHDC_A_OUT -26.42974987030029 0.5681787139183535
C1:HPC-BHDC_B_OUT -28.60767822265625 0.630590120803355
C1:LSC-TRX_OUT_DQ 0.8131266951560974 0.06610630013789652

FPMI locking:
 - We had to change the following parameters to restore FPMI locking.

C1:LSC-OUTPUT_MTRX CARM to MC2 component to -1.65 (from -0.734, to account for MC2 actuation being about a half now; see 40m/17886)
C1:LSC-AS55_PHASE_R to -166 (from -177.9, to minimize CARM to AS55_Q coupling)
C1:LSC-REFL55_PHASE_R to 96.22 (from 75.92, to minimize CARM to REFL55_Q coupling)
C1:LSC-PD_DOF_MTRX REFL55_I to CARM_B component to 0.4536 (from 0.567, to balance between POX11_I+POY11_I)

 - These new values were obtained using SENSMAT and transfer function measurements between DARM_A and DARM_B (Attachment #6), CARM_A and CARM_B (Attachment #7). Red is measured OLTF, and blue is expected OLTF when using "B" signals (real FPMI RF signals). Red and blue should be equal to hand off.
 - Measured UGF was ~150 Hz for DARM (Attachment #6), ~200 Hz for CARM (Attachment #7), and ~30 Hz for MICH.
 - FPMI noise spectra was measured, and compared with that from January 2023 (Attachment #8). FPMI sensitivity looks the same as before . 60 Hz noise is also not worse, probably because of common mode rejection.

Next:
 - Investigate ETMX damping
 - Investiage clipping in IFO to make a check list for the vent
 - Investigate excess noise in single arm. Possibly from MC dewhitening filters? (not a problem right now)
 - Restore PRMI 1f and 3f lockings
 - Restore ALSY and ALSX
 - Try high bandwidth CARM (if necessary)
 - Lock PRFPMI with ALS