Stopped by lab today. Found all suspensions undamped (even though watchdogs never tripped), same symptom as CDS crash from earlier this month. Fixed as per last ocurrence--- by restarting all models and burt restoring.

[Tega Koji]

Last week, Tega gave me a brief introduction to the configuration of the summary pages. So this is the summary of the conversation.

1. General info resources

40m wiki https://wiki-40m.ligo.caltech.edu/DailySummaryHelp
40m wiki https://wiki-40m.ligo.caltech.edu/40mLDASaccount
40m git lab https://git.ligo.org/40m/40m-summary-pages

2. How the frame files are transfered

The frame files are created in /frames on fb1. ==> If the frame files are not found on fb1, it's the problem of FB/CDS.
This directory is exported to nodus (as /frames) via NFS. ==> If the frame files are not found on nodus (i.e. /frames is not found), it's the NFS problem between fb1 and nodus.
rsync executed on LDAS comes to nodus to pull the files to /hdfs/40m on LDAS. ==> If the frame files are not found on ldas, it's the rsync problem. We are not controllying this file transfer. Contact with Dan Kozak

3. How to get into LDAS

Look at the LDAS account wiki page on the 40m wiki. For me "ssh -J" approach didn't work. So I used "multi-step login", starting from "ssh albert.einstein@ssh.ligo.org"

4. How the proess is running

This summarizes the workflow very well: https://wiki-40m.ligo.caltech.edu/DailySummaryHelp#Technical_info

I am still not sure how the main script "gw_daily_summary_40m" is running every 30min as well as gw_daily_summary_40m_rerun.
Otherwise, the following scripts are running via crontab of the 40m account
0,30 * * * * /home/40m/DetectorChar/bin/plot-summary-job-duration ~/public_html/detcharsummary/summaryDiag.pdf
5,35 * * * * /home/40m/DetectorChar/bin/checkstatus
6,36 * * * * /home/40m/DetectorChar/bin/plot-temperature
7,37 * * * * /home/40m/DetectorChar/bin/pushnodus
27 18 * * * /home/40m/DetectorChar/bin/cleanLogs

The produced files are not in /home/40m/public_html/detcharsummary , the data processing has a problem.
If the files are there but not pushed to the 40m (by pushnodus), the file transfer has an issue.

Three additional mode cleaner alignment controllers were tested Sunday night (remotely). They were run in tandem with the (recently improved) standard controller. Each test consisted of five minutes with pitch alignment uncontrolled, five minutes with the standard controller only, and twenty minutes with both controllers enabled.

GPS times for each phase of testing were the following:

1. slug_functional
   • Open loop 1355466269
   • Closed loop 1355466579
   • Policy 1355466987
2. slug_hippocamp
   • Open loop 1355468210
   • Closed loop 1355468520
   • Policy 1355468849
3. slug_hippocamp_slow
   • Open loop 1355470093
   • Closed loop 1355470403
   • Policy 1355470855

While recovering from the power outage, I took the opportunity to try having the timing system trigger on the rising edge of the 1 PPS signal from the GPS receiver (rather than the falling edge, as it had been doing since before the CDS upgrade). This was done in order to eliminate a timing offset between the clock used by the ADCs and the IRIG-B timestamps from the Spectracom boards. It was successful in that regard, and cleared the timing errors seen in the IOP statewords on most of the front ends.

The two exceptions were c1lsc and c1sus, where something is broken with the DuoTone readbacks. The attached plot shows the DuoTone signal in the last channel of ADC 0 on c1x01 (working normally) vs c1x02 and c1x04 (busted).

However, this change apparently also had some unexplained effect on the way the c1sbr model runs. There were frequent CPU time overruns and IPC errors. So on Sunday afternoon I reverted to the falling-edge trigger. This caused the timing errors to return, but allowed c1sbr to run normally.

[Yuta, Paco]

We tried restoring the FPMI BHD readout from yesterday but failed. Below is a summary of what we did.

Steps

1. Align arms, MICH and LO (using ITMY single bounce).
2. Lock both CARM and DARM with POX/POY to restore the "electronic" FPMI.
3. Lock MICH with REFL55_Q.
4. Handoff DARM to AS55_Q and CARM to REFL55_I.
5. Lock LO_PHASE using BH55_Q
6. Balance BHD_DCPD to remove offset in BHD_DIFF
7. Measure the C1:LSC-BHDC_DIFF_OUT / C1:LSC-AS55_Q_ERR ratio to get the DARM content in BHD DIFF.
8. Attempt DARM control handoff from AS55_Q to BHDC_DIFF  --- this step didn't work today despite our several attempts.

We found LO fringe alignment to be really important, as sometimes we would try to calibrate the DARM content of BHD DIFF and found almost no coherence between AS55_Q and BHD_DIFF, but after realigning the coherence was increased and the lock was better. Another difference with respect to yesterday was the sign flip implied by the measured ratio from step 7.

Calibrated FPMI noise spectra

In anticipation to restoring FPMI BHD, we took a calibrated FPMI noise spectra (error and control point). The saved diaggui template that produces Attachment #1 is on /cvs/cds/rtcds/caltech/c1/Git/40m/measurements/LSC/FPMI/FPMI_calibrated_noise.xml Our calibration was based on sensing matrix measuring the DARM content on AS55_Q which was 1 / (2.617 * 3.64e11 counts/m) =  1.0497e-12 m/count, and the (balanced) ETM plant = 10.91e-9 / f^2 m/counts.

Next steps

Sadly we couldn't take a FPMI BHD calibrated noise spectra, but things to look into next time are

• Take TFs for FPMI CARM, DARM and MICH loops. We skipped this today, perhaps wrongfully so.
• Measure the FPMI sensing matrix to check demod phases and optical gains (related to the above).

That's great - I think this solution will be best. Having the PLLs actually gives us some problems - the square wave action in these demod boards because of the ECL drives pollutes the air with all the harmonics.

In the future, it would be best to get rid of these boards and just use the new aLIGO boards with a direct LO feed.

[Anchal, Paco, Yuta]

FPMI locked with BHD readout!!!

Paco and I figured the repeatable recipe for locking FPMI today. The settings are saved as snapshot file. In short, we first lock fake FPMI using POX+POY and POX-POY and then locking MICH to REFL55_Q. We make sure there are no offsets in AS55Q or REFL55Q. Then we handoff CARM and DARM loops to 0.496*REFL55_I and 2.617*AS55_Q by changing gains on A and B paths simultaneously with tramp time of 5s. WE have pushed new measurements of CARM, DARM and MICH loop OLTFs to measurement repo.

We turned on 5 oscillators all sending calibration lines to ITMY at different frequencies to calibrate DARM readout. WE took this data for about 90 minutes and then decided to try locking FPMI with BHDC DIFF.

A simple handoff to 0.68*BHDC_DIFF at error point for DARM loop worked. The OLTF for DARM loop remained the same.

I need to run now, so more detailed elog will come later.

On another news, this was last day of Tega, a warm farewell to him.

[Anchal, Yuta, Paco]

Late elog (from yesterday) -- We locked FPMI, YAUX, and turned on calibration lines from gpstimes = 1355539386 to 1355539594 (lost lock because IMC unlocked )

We followed the steps in this elog and handed off from an electronic FPMI (POX, POY) to the RF one (REFL55 and AS55). We will continue this work today and try to finish a restore FPMI script to make it more robust.

I played with the PLL bit more today to understand the issue. From what I understand, the following is the summary:

Moku as VCO in WFS demod board PLL:

• Moku input in VCO mode is actually limited to ~ +/-21 V contrary to what it says on the app (10 Vpp)
• Whenever the VCO tuning signal goes beyond this range, Moku just ignores the input and sends a pure sine wave at the carrier frequency.
• I think because of this rail point behavior, the PLL goes off to a bad mode where the VCO tuning signal from demod board rails to +15 or -15V, and thus Moku does nothing to correct for it.
• I found a deterministic way of catching lock with Moku VCO:
  • With whatever carrier frequency, set the VCO slope to at least 1 MHz/V (10 MHz/V is better).
  • The VCO tuning signal most probably would rail to +15V or -15V.
  • Reduce +/- 15V supply, this moves the railing voltage with it.
  • When the voltage rails reach +/2 V, the PLL catches the lock.
  • Now slowly ramp back the power supply back to +/- 15V.
• This way I was able to repeatedly catch the lock (see attachment 1), but of course, this can't be done when our board is mounted in the Eurocrat.
• So I thought if I attenuate the VCO tuning signal by 20 dB and pass it through an SR560, I can control the VCO tuning signal amplitude. This approach however did not work. It was always required to reduce the +/- 15V supply to the board to catch the lock.
• This makes me think that the phase detector chip AD9901 needs to be turned off initially or supplied with low voltage rails. I'm not sure why.
• With this, I think we should scrap this idea of using Moku as VCO, it will be just too unreliable.
• So we need to move to the possibility of feeding 22 MHz signals to the WFS demod board where VCO output goes.

Basically, we make our own PLL outside the board to generate 2 times LO frequency or we create 2 times LO frequency by second harmonic generation.

Moku:Pro as a frequency multiplier

This white paper from liquid instruments describes how Moku:Pro can be used as a frequency multiplier in the phasemeter app now. This functionality however has not been extended to Moku:Lab, so in 40m, we can not do this right now. If we get access to Moku:Pro, following will be required:

• Send 11 MHz LO signal to Moku:Pro input 1 with phasemeter app on.
• Select frequency multiplier option of 2 at the output 1. Set voltage to 2 Vpp and feed this signal to VCO RF out port on the modified demod board.
• Leave VCO tuning port unconnected.
• This way we would replace the internal PLL with Moku digital PLL. Moku's PLL can be run upto 10 kHz bandwidth and would be very robust for such use.

Second harmonic generation using mixer and bandpass filter

• Split the 14 dBm 11 Mhz output from frequency generation box (I simulated this with benchtop function generator) using a splitter.
• Send both outputs to ZP-3+ mixer (level 7).
• Filter the output with SBP-21.4 band pass filter. Koji has measured this filter in 2013. See elog 40m/9010.
• Amplify the output twice, first with ZFL-500HLN+ (20dB amplification), then with ZFL-1HADX (11 dB).
• This setup provides enought output amplitude for the comparator chip AD96687 to generate clean ECL signal at 22 MHz without slipping. With only 20dB amplification, I could see the phase slip by 180 degrees enough times that the oscilloscope shows both outputs overlapped.
• Attachment 2 shows the ICLK and QCLK signals generated by the board with this setup.

Next steps:

• I'll modify one more board for sending in LO like this.
• I'll test the demodulation performance of the board with LO input from the second harmonic generation.
• Setup the optical path for AS WFS.

I've turned off HEPA fan and all lights at:

PST: 2022-12-16 22:06:53.830911 PST
UTC: 2022-12-17 06:06:53.830911 UTC
GPS: 1355292431.830911

Tuned on HEPA again:

PST: 2022-12-17 14:39:57.974212 PST
UTC: 2022-12-17 22:39:57.974212 UTC
GPS: 1355352015.974212

I've turned off HEPA fan and all lights at:

PST: 2022-12-17 17:26:28.740675 PST
UTC: 2022-12-18 01:26:28.740675 UTC
GPS: 1355362006.740675
 

I also started WFS relief script at this time. This script would end in 600s from the above time.

[Koji, Anchal]

short version: We checked signals at different points in the circuit to make sense of why it was not working. We found out that teh comparator chip AD96687BR was not working as expected and was not converting the analog signal from our VCO or LO inputs to ECL. We tested 2 other spare board with same behavior. We decided to try replacing the comparator chip with a new one, and indeed that was the issue. The new chip was working as expected and we are able to get PLL lock on the board with Moku:Lab as the VCO. However, there are some issues that need to be ironed out. The PLL does not catch lock right away and we could not figure our a systematic way of reaching to a locked state. That smells fishy to me as in my experience, when PLLs work, they work very robustly. More analysis with data and figures will follow. For now, we have some hope that this can work.

There is always the option of not closing PLL loop and injected twice the demodulation frequency at the VCO port that we have access two. For this, I'll need to create a SHG unit for 11 MHz with 21.4 MHz BLP. I'll look into this solution as well.

[Paco, Yuta]

We have recovered the IFO alignment (FPMI and BHD) for the first time after the power loss on Dec 15th 11:30 AM PST.

PMC and IMC transmission
~>cdsutils avg -s 10 C1:PSL-PMC_PMCTRANSPD C1:IOO-MC_TRANS_SUMFILT_OUT
C1:PSL-PMC_PMCTRANSPD 0.7332153499126435 0.0004376671844386436
C1:IOO-MC_TRANS_SUMFILT_OUT 14370.22451171875 38.87278766402092

BHDC PDs with LO beam only
~>cdsutils avg -s 10 C1:HPC-BHDC_A_OUT C1:HPC-BHDC_B_OUT
C1:HPC-BHDC_A_OUT 111.07633819580079 2.916326545853983
C1:HPC-BHDC_B_OUT 96.85788955688477 2.4419271045522506

Arm transmissions
~>cdsutils avg -s 10 C1:LSC-TRY_OUT C1:LSC-TRX_OUT
C1:LSC-TRY_OUT 1.0163812279701232 0.02008742269699207
C1:LSC-TRX_OUT 0.9274496018886567 0.027689954466601815

MICH fringe with ETM misaligned
See Attachment #1

LO-ITMX single bounce fringe with ITMY misaligned
See Attachment #2

I corrected the filter module location for 28 Hz ELP filter on MC1 and MC3 coil output filter banks to FM8 (from FM9). FM9 is always reserved for SimDW (which is simulated dewhitening filter and is supposed to be a copy of the dewhitening filter on the analog side). FM10 is also reserved for InvDW filter which performs the anti-dewhitening before DAC. This filter module, FM10, shoudl remain on always. When FM9 is on (SimDW), the analog dewhitening turns off and we get a flat digital response as well. When FM9 is off, the analog dewhitening is turned on. Nominal operation configuration right now is to not use the coil dewhitening and keep FM9 and FM10 on always.

PMC seems to have gotten very misaligned over the last 12 hours. I'm going in to align now.

[Paco, Anchal, Koji]

A possible long-hidden bug of MC2 dewhitening switching was found and fixed.
MC2 coil dewhitenings were always on without proper compensation. MC1/3 also had a similar issue.
Now "SimDW" and "IncDW" filters were set on FM9 and FM10, and they properly deal with the DW state, which is switched by FM9.

We tried restoring FPMI configuration this afternoon. For this we tried the following:

1. Lock PSL to YARM (through MC2) using the CARM LSC filter.
    a. Input: 1 from POY11_I
    b. Output: -17.5  to MC2
    c. Gain: 0.009
    d. Locking FM: FM5 only
    f. Trigger: TRY with 0.3, 0.1 thresholds
    e. FM Trigger: FM1, FM2, FM3, FM6, and FM8
2. We lock XARM to PSL (through ETMX) using the DARM LSC filter.
3. A simple handoff of the error and control points didn't work at first.

    a. We decided to look at the actuation strength of MC2 relative to ETMY. By locking the YARM using POY11, we measured the actuation transfer functions on two control points ETMY and MC2  referenced to the YARM cavity. Our expectation was a flat response in the ETMY control point, and a scaled, nominally flat response on MC2 so the ratio between the two give us the right output gain.
    b. A first suprise was found when exciting at MC2; here we observed a steep frequency dependent response, which suggested the MC2 actuation was weaker by over an order of magnitude.... Since this didn't make sense, after a little investigation and Koji's help, we figured out the issue was with the MC2_COIL SimDW and InvDW filters! These filters were on FM7 and FM8, but their outputs were not affecting the state of the analog electronics DW filter! After reviewing the model and comparing against ETMY, we figured we should change them to FM9 and FM10. This change successfully addressed the bogus frequency dependence (which was just the oblivious electronic DW filter gain).

On Monday I aimed to measure the transfer function of the x-arm AUX PDH loop while momentarily locked, with a Moku:Go. I re-aligned the XEND green beam input to the arm cavity with M1 and M2 steering mirrors. I got GTRX to ~1.4 and the TEM00 mode nominally locked (back to ~5 seconds of lock, like last time). Previously Paco and I had achieved transmission of 3, so there was still a good way to go in mode matching. 

However I noticed the backwards-propagating beam started to drift relative to the opening of the Faraday isolator (located after the shutter). During manual alignment the backwards beam cleared through the aperture of the FI, but around 5 minutes later it had drifted too high and the beam spot was visible against the FI body, missing the aperture. At this point transmission had dropped to 0, and I realigned the beam to clear through the opening. I tried to further increase transmission but the drift continued to occur within a few minutes of re-alignment. I double checked that there was no dithering of ITMX or ETMX. It seemed there was high residual motion of the ETM, but I was not sure how to decrease this (damping filters were on). I moved on to setting up the TF measurement and decided to return to alignment once the loop excitation was configured.

I chose to inject an excitation from the Moku at the error point of the PDH servo box. I set up the measurement from 100 kHz to 100 Hz, zoomed in around the loop UGF. I passed the mixer output / error signal (alpha) to a T-splitter and sent one copy to input A of an SR560, and routed the Moku excitation to input B. The summed output of the SR560 was sent to the PDH servo input (beta). I passed the second copy of the error signal (alpha) to the Moku, along with the servo input monitor signal (beta) from the PDH box. The Moku measured the transfer function alpha/beta to obtain G_OLG. 

I returned to align the green beam and recovered flashing of the TEM00 mode. However when I closed the loop (with excitation), it didn't catch lock. I quickly reverted the loop back to its original state and confirmed that TEM00 locked for ~5 seconds. This made me think the excitation signal was too large relative to the error signal, so I reduced its amplitude to 500 mVpp. This still didn't recover the lock, and at this point the alignment had drifted again so I decided to wrap up. 

TODO:

I am working remotely for the next week, so I can carry out these steps in January.

I've turned off HEPA fan and all lights at:

PST: 2022-12-13 23:49:12.955214 PST
UTC: 2022-12-14 07:49:12.955214 UTC
GPS: 1355039370.9552

Turned HEPA back on:

PST: 2022-12-14 10:47:49.944161 PST
UTC: 2022-12-14 18:47:49.944161 UTC
GPS: 1355078887.944161

with the new output matrix, we repeated the diagonalization script that Anchal ran previously. In the attached plot you can see that as we successively apply offsets to the WFS1, WFS2, and MC_TRANS Pitch loops, there is the offset in the loop we offset, but there is no appreciable step seen in the other loops.

Maybe we could do better, but this is the best DC diagonalization I have ever seen in this system. So we should just keep it for now.

At some point, we should run this procedure for YAW as well, but not urgent.

[Radhika, Paco]

I modeled a digital filter for adding a resonance at a desired frequency (Q~100), with a complex-conjugate pole pair and 2 real zeros (2nd order system). Paco suggested I start with a 575 Hz resonance. I loaded the digital filter onto the Moku using the Moku python API (script at labutils/moku/mokuGoPro/mokuDigitalFilter.py). I tested the filter by feeding the Moku a 2 Vpp signal around 575 Hz and looking for some noticeable gain - however the signal passed though unchanged. There might be an additional Moku command for enabling the filter - I'll look into this.

TODO:

[Rana, Koji]

The IMC WFS pitch Output Matrix was recalculated based on a DC Sensing Matrix measurement.

The IMC and the WFS heads were realigned and the WFS offsets were reset. The WFS servo is running stably for ~1.5hrs now.

Using Rana's test with the optic offsets, the sensitivity of the sensors against the misalignment of each optic was measured.
First of all, we accessed the recorded 900s data on Dec 9 2022 12:48:00 UTC (Attached 1). This DTT XML file is stored in /users/koji/221209/221209_IMC_WFS_PIT.xml

You can see the attachment that the foton style smoothing filter was used to reduce high freq noise above 0.1Hz.

Then the averaged values were read from "Cursor" tab (Attachment 2). This gave us this following sensing matrix.

Null to {WFS1P, WFS2P, MCTransP}
-36.7 +/- 90
401   +/- 200
-19.4 +/- 5

MC1 to {WFS1P, WFS2P, MCTransP}
2870 +/- 150
 910 +/- 150
1240 +/- 7

MC2 to {WFS1P, WFS2P, MCTransP}
  3950 +/- 200
-21700 +/- 490
  1210 +/- 13

MC3 to {WFS1P, WFS2P, MCTransP}
 -988 +/- 100
-7870 +/- 350
 1010 +/- 4

The inverse of this matrix is
           To MC1    MC2    MC3
From WFS1    1.2    1.0    -2.7
From WFS2    0.5   -0.4    -0.1
From MCT     5.0   -2.2     6.1

This is transposed for the MEDM output matrix. So the actual output matrix tried was

From WFS1  WFS2   MCT
     1.2    0.5   5.0   to MC1
     1.0   -0.4  -2.2   to MC2
    -2.7   -0.1   6.2   to MC3

We then individually tested the servo stability and the response to the input offset.
This matrix seemed indeed well diagnalized w.r.t the sensors. We injected the error signal offset in the MCTrans Pitch servo. This didn't reduce the IMC Trans indicating that the WFS1/2 were still as it was while the spot position was displaced. (very nice!)

The new matrix made all the pitch loops stable with negative gains (-0.1, -0.2, -0.5) together with the input gain slider of x1.0. The servo also worked together with the presence of the Yaw loops. Good.

The WFS1 gain was a bit too low. So we wanted to give 50% boost.
We decided to multiply the matrix elements by -0.3, increasing the servo GAIN fields by  -1/0.3. The resulting servo gain settings and the output matrix screen look like Attachment 3.

Then the IMC was aligned so that the reflection is minimized while the MC2 trans goes onto the center of the QPD.

Then the WFS offset script has been run with low and stable IMC Reflection DC (Attachment 4)

• MEDM video switches didn't work - "sh: 1: /opt/rtcds/caltech/c1/scripts/general/videoscripts/videoswitch3: not found"
  • This was fixed by modifying #! from /usr/bin/python to /usr/bin/python3
• [IMPORTANT!] ezca* not found: ezcaread/ezcawrite/ezcastep/ezcaservo
  • This broke IMC WFS reied script

    This will start a relief servos for 600that can not be stopped once started
Do you want to continue (y/n)? y

    Starting the 600 second relief servos...

    /opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 28: ezcaservo: command not found
/opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 30: ezcaservo: command not found
/opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 33: ezcaservo: command not found
/opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 29: ezcaservo: command not found
/opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 31: ezcaservo: command not found
/opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefMCWFS: line 32: ezcaservo: command not found

    Done relieving

    
    hit any key to close

• [IMPORTANT!] emacs editor does not work - "emacs: symbol lookup error: emacs: undefined symbol: malloc_set_state, version GLIBC_2.2.5"
   

Also reply to: 40m/16125

I migrated the code used in 40m/16125 to our scripts git repo and used it to apply offsets to IMC optics and noticing the parabolic change in the transmission values. Fitting the data with parabola and using the calculations mentioned in the previous post, we get following angular actuation calibration at DC from the PIT/YAW alignment output channels (cts) to actual motion in (urad):

*Note that in the previous post, the radius of curvature of MC2 used was wrong and has been corrected in this calculation to 17.87 m taken from Gautam's thesis Table A.1

Due to lack of time, we ran test faster on MC2, hence more uncertainty in it's results. Also, during MC1 YAW test, lock for breifly lost which required me to manually throw away some data points, but it did not affect the quality of fit much. Please see attached the data plots and fit.

For calibration at AC, another test needs to be performed which I did not do right now. 40m/16125 also describes how to do that, so someone can repeat that in future.

[Yehonathan, Yuta]

Here's a plot using same dataset from yesterday, but x-axis in raw BH55_Q data, not calibrated into degrees in LO phase.
This way you are free from calibration error in BH55_Q data to LO phase.
Elliptic fit is done using least squares.
dphi is calculated using the following equation where (ap, bp) are the semi-major and semi-minor axes, phi is the rotation of the semi-major axis from the x-axis.

beta=np.arctan(ap/bp/np.tan(phi))
dphi=-np.arctan(ap/bp*np.tan(phi))-beta

dphi gives you LO phase at zero-crossing.
For example, the top plot says that the sensitivity of BH55_Q to BS crosses zero at "-133.92 deg," which means BH55_Q+MICHdither can lock LO phase at -134 deg or 46 deg.
The top plot also says that the sensitivity of BHDC_DIFF to BS crosses zero at "127.45 deg," which means BHDC_DIFF sensitivity to MICH maximizes at 38 deg or 217 deg.
The middle plot says that the sensitivity of BH55_Q to LO1 crosses zero at "90.09 deg," which means BH55_Q+LO1dither can lock LO phase at 90 deg or -90 deg, and BH55_Q(no dither) can lock LO phase at 0deg or 180 deg (by definition).

Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/SensingMatrix/PlotSensMatBHDvsLOPhaseData.ipynb

Next
 - Use also BH55_Q+LO1/AS1dither to scan around 90 deg.

Today I set out to align and lock the YEND green laser, and observe the expected PDH error signal and PZT control signal. 

- I took note of PDH servo knobs:

- Disconnected PDH servo PZT output to break loop

- Scanned pitch and yaw of steering mirrors 1 and 2 [Attachment 1] and achieved transmission ~1.2.

- Re-engaged the loop and with TEM00 locked, and did fine adjustment of steering mirrors to maximize transmission to 1.4.

- At this point I broke the loop again to look at the PDH error signal and piezo control signal in an oscilloscope. The error signal had high frequency noise, so the SR560 was used to low pass it before sending it to the scope.

- Once I reconnected the loop and locked to TEM00, I noticed lots of noise in green transmission. Paco took spectra of GTRY and found it was line noise at multiples of 60 Hz. I checked if any BNC shields at the servo box were touching. I shifted the LO frequency from 213.12 kHz to 213.15 kHz, so that the modulation/demodulation was not an integer multiple of 60 Hz. However, these steps didn't get rid of the line noise. To be further investigated.

Next I plan to revisit the XEND AUX loop and try to reach higher lock stability. 

I made a script to toggle the offsets in the MC SUS so that we can see the resulting error signals in the MC WFS / MC-TRANS_QPD.

I ran it just before 5 AM local time Friday morning.

It goes in order and applies a 50 count offset to the pitch filter banks. During this test the input to the IMC WFS servos is set to zero, so that the integrators hold the mirror position in the aligned state.

I will analyze this 3x3 measurement and post the resulting sensing matrix soon. It would be good if someone can post here the actuation calibration in radians, so that we can have a physical calibration of the sensing matrix in counts/radian.

Based on the previous two elog posts, Koji and I decided that we should use 11 MHz signal for arm cavity ASC and modify a spare WFS demod board to work at 11 MHz. This board LIGO-D980233, uses a PLL to lock the to LO input and generate I and Q ECL clock signals from it. For this purpose, it uses POS-XX minicircuits VCO. For IMC WFS boards the model number is POS-75 and with the board design, it can work for 18.75 MHz to 37.5 MHz modulation frequencies.

To make it work for 11 MHz, we have to swap this with POS-25 but that is not available for purchase anywhere. So Koji and I decided to use Moku:GO as a VCO and make connections to the pin holes on the board. Today, I modified a spare WFS board to make this possible. I added a right angle SMA connector to take in VCO output signal and a BNC connector to send out tuning signal. See attached photos for the details of this hack.

Then I went to 1X2 and tried on this modified board on a Euro crate empty slot. I used Moku:GO in a multi-instrument mode in which first instrument was a Waveform generator set to modulate from external input 1 at 6 MHz/V. The output RF level was checked on an oscilloscope and increased until I got about 9.5 dBm power at the output. The second instrument was just an spectrum analyzer to see if the test output from ICLK looks ok. I fed LO from a spare output port on RF distribution box for 11 MHz signal. I made sure to attenuate this signal to get 2 dBm LO signal which is the case for the WFS demod board LO input as well. 

This test however failed. I could not see any signal from ICLK or QCLK output. I then tried to use the same slot as the demod board for WFS1 is used and I still did not see any output on ICLK or QCLK. I split the VCO tuning signal coming from the board to see it on an oscilloscope and it was mostly noise of ~1 mV level. I then tried to check ICLK and QCLK on oscilloscope and saw that they had a huge offset of -1.7 V. I suspect some ground mismatch issue between Moku:GO and the demod board.

I decided to call it a day here.

I reset everything back to how it was on the rack and turned on IMC WFS again. It is working as usual keeping lock steady for atleast last 20 min that I have seen it.

[Yehonathan, Yuta]

Sensing matrix measurements at different LO phases were performed under LO phase locked to both BH55_Q and BH55_Q+MICH dither.
We confirmed that BH55_Q+MICHdither can lock LO phase to around maximum MICH sensitivity for BHD_DIFF.

Locking configuratons
 - MICH was lockied using AS55_Q feeding back to BS, at dark fringe. Notch at 311.1 Hz was turned on. C1:LSC-MICH_GAIN=-6 (lowered to reduce BS DAC saturation).
 - LO PHASE was locked using BH55_Q, feeding back to LO1. FM2, FM5, FM8 on. C1:HPC-LO_PHASE_GAIN=+/-2.
 - LO PHASE was also locked using BH55_Q+MICHdither. BS was dithered with C1:HPC-BS_POS_OSC_CLKGAIN=4000 at 281.768 Hz (2nd notch of ELP80 used for demodulation). Feeding back to LO1. FM5, FM8 on (no LF boost). C1:HPC-LO_PHASE_GAIN=+/-20.
  -- Note that we could not increase the dither amplitude more as BS DAC starts to saturate (we are using BS for MICH loop, sensing matrix measurement, and audio dither; see 40m/17343).

Sensing martix measurements
 - Lines are injected to BS @ 311.1 Hz with amplitude of 1000, LO1 @ 147.1 Hz and AS1 @ 141.79 Hz with amplitude of 5000.

Estimating LO phase
 - Estimation of LO phase was done in the same way described in 40m/17287. We used measured sensitivity of BH55_Q for LO1 at BH55_Q zero crossing (-1.42e9 counts/m) to estimate LO phase offset from BH55_Q zero crossing.
 - In BH55_Q+MICHdither case, LO phase was flipped using the following equation when C1:HPC-LO_PHASE_GAIN is minus (to have consistend LO phase dependence with BH55_Q locking. NEEDS CHECK).

LOphase = 180 - arcsin(BH55_Q/A)

Result
 - Attachment #1 shows the sensitivity of AS55, BH55, BHDC_DIFF/SUM to BS (upper panel), LO1 (middle) and AS1 (lower), under LO phase locked to BH55_Q. The upper plot is the same plot as 40m/17287. As we can see, "0 deg" in the x-axis is not the optimal phase for BHDC_DIFF to have maximum MICH sensitivity. "0 deg" is the optimal point in terms of BH55_Q sensitivity to LO1/AS1, as we tuned the demodulation phase to maximize it.
 - Attachment #2 shows the same plot, under LO phase locked to BH55_Q+MICH dither. Sensitivity of BH55_Q to MICH crosses zero at round these measurements, as we are zero-ing it with this locking scheme. Around these LO phases, sensitivity of BHDC_DIFF to MICH is maximized as expected. Also, sensitivity of BHDC_DIFF to LO1/AS1 is minimized, as expected (assuming residual MICH offset and contrast defect are small).
 - Attachment #3 is the combined data from #1 and #2. Data points from BH55_Q locking are marked with "o" and those from BH55_Q+MICH dither locking are marked with "x" (they have larger uncertainties in LO phase). Both measurements are somewhat inconsistent in some channels (BS to BHDC_DIFF and LO1/AS1 to BH55_Q). Needs further investigation.
 - Dashed lines are from scipy.optimize.curve_fit using the following fitting function.

def fitfunc(x, a,b,c):
    return a*np.sin(np.deg2rad(x-b))+c

Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/SensingMatrix/SensMatBHDvsLOPhase.ipynb

Next:
 - Lock MICH with BHDC_DIFF under LO phase locked to BH55_Q+MICHdither
 - Estimate LO phase noise contribution to MICH displacement sensitivity
 - Improve LO phase loop
 - Try audio+audio dither
 - Move on to FPMI
 - Move on to 44MHz
 - Estimate the amount of residual MICH offset and contrast defect from these plots

[Anchal, Paco]

After debugging the hardware, on gpstime 1354422834 we turned on 5 cal lines on ITMY to test the ALS calibration for the single arm along with our error estimates.

Note: the YARM IR lock lasted > 8 hours, but the GRY transmission dropped twice during the evening and hopped back up, so the phase tracker jumped a couple of times.

Configuration

YAUX laser was locked to the YARM through the analog PDH servo (UGF ~ 2 kHz), YARM was locked to the PSL with POY11 (UGF ~ 200 Hz), and the ALS phase tracker was set to output the beat frequency noise in Hz. HEPA was left on during this measurement. The oscillators were similar to previous instances: gains of 70@211.1Hz, 100@313.31Hz, 100@315.17Hz, 300@575.17Hz and 15@30.92Hz with appropriate notches on ETMY to avoid POY11 loop supression.

Analysis

For YARM, the high bandwidth YAUX laser loop with transfer function G ensures that the relative laser frequency fluctuations correlate with the relative length fluctuations as:

Then, getting the magnitude of the YARM displacement at calibration frequencies is possible by knowing the arm cavity length, open loop gain, and absolute frequency (wavelength). The relative calibration error on the magnitude of the displacement is

including the relative uncertainties in the YARM length, wavelength, and open loop gain. Interestingly, the loop gain term weighs proportionally less as G increases, so even if G = 100 (10), its relative error contribution would be < 1%. To estimate our total error, we assume the wavelength and YARM length are 1064.1(5) and 37.79(1), and add the frequency dependent values for G with 10% error. Finally, we use the rms ASD to estimate the relative error from the beatnote fluctuation measurement.

The measurement was done similar to other instances, taking the 'C1:ALS-BEATY_FINE_PHASE_OUT_HZ_DQ' timeseries (sampled at 16 kHz) and demodulating at the calibration frequencies above to get the mean YAUX laser frequency fluctuation and its uncertainty from the demodulated rms ASD.

Results

Attachment #1 shows the raw timeseries, Attachment #2 shows the spectra around the cal lines, Attachment #3 shows the demodulated timeseries, Attachment #4 shows the final result for the 5 lines, including the tallied errors as detailed above.

ITMY actuation = 4.92(11) nm / count / f^2

Discussion

We compared our results from Attachment #4 against a MICH referenced ITMY actuation calibration found here; which Yuta guess-timated a 10% uncertainty (gray shaded band in Attachment #4). An important correction came for the 575 Hz line, not just because the YAUX OLG is small but because a violin filter on ITMY LSC output has a 1.4475 gain bump. In fact we collected any additional digital gains from the ITMY output filters:

Next

• Consider moving the 575 Hz line to avoid additional digital gain, but try to remain at high frequency.
  • Maybe here we can use the resonant gain MOKU filters that Radhika is designing.
• Setup a live loop gain calibration to reduce the uncertainty for the high frequency cal line.
  • We can also just grab GTRY (transmission) as a proxy for optical gain and use for budgeting.
• Work on setting up constraints for error mitigation based on allan deviation of the beatnote and PDH nonlinearity.
• Move this to FPMI or some other lock configuration

[Yehonathan, Yuta]

We found that moving AS1 in yaw improves power on ASDC and AS55.
We compensated this move with AS4 and SR2 to keep the BHD fringe (ITM single bounce and LO beam fringes ~600 counts in amplitude at BH55).
We have also aligned BHD CCD camera to avoid clipping on a lens just before the camera (all the other optics on ITMY table remain untouched).
After the alignment, MICH BHD sensing matrix were measured with new C1CAL model (40m/17339) under the following conditions.
 - Locked MICH with AS55_Q at dark fringe. Notch at 311.1 Hz was turned on.
 - Locked LO PHASE with BH55_Q with C1:HPC-LO_PHASE_GAIN=-2, using LO1.

Sensing matrix with the following demodulation phases (counts/m)
{'AS55': -161.16488964312092, 'BH55': 162.57275834049358}
Sensors      BS @311.1 Hz           LO1 @147.1 Hz           AS1 @141.79 Hz           
AS55_I       (-0.19+/-1.45)e+07    (-0.26+/-2.43)e+06    (+0.35+/-2.39)e+06    
AS55_Q       (-1.74+/-0.02)e+09    (+1.61+/-8.31)e+06    (+1.08+/-8.59)e+06    
BH55_I       (+3.01+/-0.17)e+09    (+3.20+/-9.59)e+07    (-3.67+/-9.46)e+07    
BH55_Q       (-6.77+/-0.45)e+09    (+1.09+/-0.17)e+09    (-1.22+/-0.18)e+09    
BHDC_DIFF    (-8.41+/-4.81)e+08    (-1.26+/-0.94)e+08    (+1.38+/-1.03)e+08    
BHDC_SUM     (-2.75+/-9.14)e+07    (+1.18+/-1.13)e+07    (-0.97+/-1.02)e+07    

AS55_Q optical gain to MICH and BH55_Q optical gain to LO phase was improved by ~45%, compared with previous measurements (see 40m/17287).
The value for AS55_Q is consistent with the free swing measurement as attached.
SENSMAT part of c1cal seems to be working fine.

We have spare WFS demods in a plastic box along the Y arm. So you don't need to modify the IMC demod boards, which we want to keep in the current state.

{Yuta, Yehonathan}

Today we lock LO phase using audio+RF method in two variants: AS1+RF and MICH(BS)+RF. We measure the TFs and find that AS1 variant has a UGF ~ 17Hz and MICH variant has a UGF ~ 32Hz.

Details

1. We lock MICH in the usual way using AS55. ITMs are aligned to make AS port dark. We use a single bounce and optimize mode-matching with LO beam by minimizing the BHDDC-A signal.

2. Using the new BHD Homodyne phase control MEDM screen we first try AS1. We put an elliptic filter with 80Hz corner frequency on the DEMOD1 filter bank. We find that the notch of that filter is at 281.768Hz and this is where we put the AS1 dither line.

AS1 is dithered with 20000 counts. We optimize the DEMOD1 demodulation angle by dithering LO1 at 27Hz and minimizing the Q quadrature in diaggui. We find that 45 degrees is the optimal demod angle. We lock the LO phase with a gain of ~ 45 and take the OLTF (attachment 1).

3. Next, we use MICH degree of freedom to lock LO phase. We dither BS with the same frequency as before with 4000 counts. Higher counts seem to put some offset on ASDC. As before we optimize the DEMOD1 demod angle and find it to be 115deg. We lock LO phase with a gain of 20 and take the OLTF (attachment 2).

I tested teh WFS demod board for possibility of demodulating 11 MHz or 55 MHz signal with it. It definitely has some bandpass filter inside as the response is very bad for 11 MHz and 55 MHz. See attached the ASD curves for the excitations seens on I and Q inputs of WFS1 Segment 2 when it was demodulated with a clock of different frequencies but same amplitude of 783.5 mVpp (this was measured output of 29.5 MHz signal from RF distribution board). See attachments 2-4 for mokulab settings. Note for 29.5 MHz case, I added an additional 10 dB attenuator to output 1.

The measurement required me to change signal power level to see a signal of atleast 10 SNR. If we take signal level of 29.5 MHz as reference, following are the responses at other frequencies:

• At 11 MHz:
  • I: -92 dB
  • Q: -97 dB
• At 55 MHz:
  • I: -75 dB
  • Q: -72 dB

Note that I and Q outputs are unbalanced as well for the two different demodulation frequencies.

This means that if we want to use the WFS demodulation boards as is, we'll need to amplify the photodiode signal by the above amounts to get same level of outputs. I stil need to see the DCC document of these board and if the LO is also bandpassed. In which case, we can probably amplify the LO to improve the demodulation at 11 and 55 MHz. THe beatnote time series for the measured data did not show an obvious sinusoidal oscillation, so I chose to not show a plot with just noise here.

[Radhika, Paco]

Paco suggested that alignment could still be the primary reason why the XEND green laser is not catching lock. With the xarm cavity aligned with IR, I adjusted the M1 and M2 steering mirrors for the green laser, looking at the REFL PD output in an oscilloscope. Paco joined and was able to achieve better mode matching by adjusting mirrors and rotating the half-wave plate. At this point, we could see TEM00 consistently flashing. Green transmission also reached a value of 3, from around 0.5 that I was able to achieve previously (this channel is not normalized).

We broke the loop to make sure the demodulated signal looked as expected, and indeed it resembled a PDH error signal. After reconnecting the loop (with the gain knob set to 3.5), Paco lowered the REFL PD gain by 3 stages and I was able to raise the gain knob to 8 without the servo saturating. I turned boost on and toggled the servo inversion until the laser started to hold lock for a few seconds. The piezo output signal looked reasonable at this point, without clipping on either end. 

After some final adjustments to the steering mirrors and the half-wave plate, the green laser can hold lock for around 5 seconds. However it's unclear why the loop isn't more stable, and more updates are to come. 

[Radhika, JC]

We retook transfer function measurements of the XEND PDH servo box, this time setting the gain knob to 3.5 to avoid saturation. Once again I toggled the boost on/off. Attachment 1 shows the resulting bode plots, which now resemble the previous measurements circa 2010. This measurement along with the previous one suggest that setting the gain knob too high might affect the loop shape in an unpredictable way. With this accounted for, it seems the PDH servo box is functioning as expected.

[Anchal, Yuta]

We have modified c1cal model to support sensing matrix measurements for BHD PDs on Friday last week.
c1cal model now can inject dither to LO1, LO2, AS1, and AS4, and demodulate BH55_I, BH55_Q, BHDC_SUM and BHDC_DIFF signals.
Related models, c1lsc, c1hpc, and c1sus2 are also modifed accordingly.
MEDM screens are also edited accordingly.
Attachments highlight the modifications.

Around 9:30 we noticed IMC going out of lock with MC1 swinging hard. It seems like the coil output shut down.

It looks like the same situation as last Monday http://nodus.ligo.caltech.edu:8080/40m/17315.

Following that elog I restarted all the models by sshing into all computers and running

Then I burt restored all models to yesterday evening point doing following on rossa:

That seemed to have worked.

 I also had to clear the WFS output to restore MC1 back to its place. Once the IMC got restored I turned the WFS again.

I took transfer function measurement of WFS2 SEG4 photodiode between 1 MHz to 100 MHz in a linear sweep.

Measurement details:

• The reincarnated Jenne laser head was used for this test. The laser diode is 950 nm though, which should just mean a different responsivity of the photodiode while we are mainly interested in relative response of the WFS heads at 11 MHz and 55 MHz with respect to 29.5 MHz.
• See attachment 2 for how the laser was placed on AP table.
• The beam was injected in between beam splitter for MC reflection camera and beam splitter for beam dump.
• The input was aligned such that all the light of the laser was falling on Segment 4 of WFS2.
• Using moku, I took RF transfer function from 1 MHz to 100 MHz, 512 points, linearly spaced, with excitation amplitude of 1 V and 100,000 cycles of averaging.
• Measurement data and settings are stored here.

Results:

Relative to 29.5 MHz, teh photodiode response is:

• At 11 MHz: -20.4 dB
• At 55 MHz: -36.9 dB
• At 71.28 MHz: -5.9 dB

I'm throwing in an extra number at the end as I found a peak at this frequency as well. This means to use these WFS heads for arm ASC, we need to have 10 times more light for 11 MHz and roughly 100 times more light for 55 MHz. According to Gautam's thesis Table A.1 and this elog post, the modulation depth for 11 MHz is 0.193 and for 55 MHz is 0.243 in comparison to 0.1 for 29.5 MHz., so the sideband TEM00 light available for beating against carrier TEM01/TEM10 is roughly twice as much for single arm ASC. That would mean we would have 5 times less error signal for 11 MHz and 40 times less error signal for 55 MHz. These are rough calculations ofcourse.

Also reply to: 40m/17255

I ran the toggleWFSoffsets.py script to generate a step response of the WFS loops in operation. Attachment 1 shows the diaggui measured time response following the parameters mentioned in 40m/17255. There are few things to quickly note from this measurement without doing detailed analysis:

• WFS2_PIT is heavily cross-coupled with WFS1_PIT and MC2_TRANS_PIT. This was also the inference from the previous post based on loop shape for WFS2_PIT loop. This needs to be fixed.
• Weirdly enough, it seems that WFS2_PIT is also cross coupled with MC2_TRANS_YAW.
• MC2_TRANS_PIT is not coupled to WFS1_PIT or WFS2_PIT. This was the major issue in last measurement in 40m/17255.
• WFS1_PIT is coupled to MC2_TRANS_PIT by about half, but is not cross-coupled to WFS2_PIT.
• For YAW, the DOFs are mostly disentangled except for a cross coupling of WFS1_YAW to MC2_TRANS_YAW by about 60%.

To get out the UGF of the loops from the step responses, I need to read this into python and apply the same filters and analyze time constants. I still have to do this part, but I thought I'll put out the result before spending more time on this.

GPSTIME: 1354314478

Just a few minutes ago, all models on FE c1sus2 crashed. I'm attaching some important files that can be helpful in investigating this. CDS upgrade team, please take a look.

I fixed this by running following on c1sus2:

Today, I worked on WFS loop output matrix for PIT DOFs.

• I began with the matrix that was in place before Nov 15.
• I followed the same method as last time to fist get all UGFs around 0.06 Hz with overall gain of 0.6 on the WFS loops.
• This showed me that MC2_TRANS_PIT loop shape matches well with the nice working YAW loops, but the WFS1 and WFS2 loops still looked flat like before.
• This indicated that output matrix needs to be fixed for cross coupling between WFS1 and WFS2 loops.
• I ran this script WFSoutMatBalancing.py which injects low frequency (<0.5 Hz) oscillations when the loops are open, and measures sensing matrix using error signals. I used 1000s duration for this test.
• The direct inverse of this sensing matrix fixed the loop shape for WFS1 indicating WFS1 PIT loop is disentangled from WFS2 now.
• Note this is a very vague definition of diagonalization, but I am aiming to reach to a workign WFS loop asap with whatever means first. Then we can work on accurate diagonalization later.
• I simply ran the script WFSoutMatBalancing.py again for another 1000s and this time the sensing matrix mostly looked like an identity.
• I implemented the new output matrix found by direct inversion and took new OLTF.Again though, the WFS2_PIT loop comes out to be flat. See Attachment 1.
• Then noting from this elog post, I reduced the gain values on MC2 TRANS loops to 0.1 I think it is better to use this place to reduce loop UGF then the output matrix as this will remind us that MC2 TRANS loops are slower than others by 10 times.
• I retook OLTF but very unexpected results came. The overall gain of WFS1_YAW and WFS2_YAW seemed to have increased by 6. All other OLTFs remained same as expected. See attachment 2.
• To fulfill the condition that all UGF should be less than 0.1 Hz, I reduced gains on WFS1_YAW and WFS2_YAW loops but that made the YAW loops unstable. So I reverted back to all gains 1.
• We probably need to diagonalize Yaw matrix better than it is for letting MC2_TRANS_YAW loop to be at lower UGF.
• I'm leaving the mode cleaner in this state and would come back in an hour to see if it remains locked at good alignment. See attachment 3 for current state.

Sun Dec 4 17:36:32 2022 AG: IMC lock is holding as strong as before. None of the control signals or error signals seem to be increasing monotonously over the last one hour. I'll continue monitoring the lock.

Mon Dec 5 11:11:08 2022 AG: IMC was locked all night for past 18 hours. See attachment 4 for the minute trend.

Another five mode cleaner alignment controllers were tested last night (remotely), running in tandem with the standard controller. As before, c1ioo was burt restored to Oct 28 and the MC TRANS PIT/YAW 80dB gain filters were disabled before the test. Each test consisted of five minutes with pitch alignment uncontrolled, five minutes with the standard controller only, and twenty minutes with both controllers enabled.

The first four tests went smoothly, but the last controller (goldfish_short) repeatedly broke the lock. Eventually I got it running with an output gain of 0.5, strong enough to see the misbehavior without unlocking the mode cleaner.

GPS times for each phase of testing were the following:

1. ichabod
   • Open loop 1354165556
   • Closed loop 1354165866
   • Policy 1354166241

1. ichabod_2
   • Open loop 1354167462
   • Closed loop 1354167772
   • Policy 1354168113

1. ichabod_3
   • Open loop 1354169357
   • Closed loop 1354169667
   • Policy 1354170006

1. goldfish_long
   • Open loop 1354171297
   • Closed loop 1354171607
   • Policy 1354172022

1. goldfish_short
   • Open loop 1354173255
   • Closed loop 1354173565
   • Policy 1354173924 (output gain 1.0, immediately unlocked the cavity)
   • Policy 1354175008 (output gain 0.1, 2 min)
   • Policy 1354175189 (output gain 0.3, 2 min)
   • Policy 1354175376 (output gain 0.5, 20 min)

Today I did a lot of steps to eventually reach to WFS locking stably for long times and improving and keeping the IMC transmission counts to 14400. I think the main culprit in thw WFS loop going unstable was the offset value set on MC_TRANS_PIT filter module  (C1:IOO-MC_TRANS_PIT_OFFSET). This value was roughly correct in magnitude but opposite in sign, which created a big offset in MC_TRANS PIT error signal which would integrate by the loops and misalign the mode cleaner.

WFS offsets tuning

• I ran C1:IOO-WFS_MASTER > Actiona > Correct WFS DC offsets script while the two WFS heads were blocked.
• Then I aligned IMC to maximize transmission. I also made PMC transmission better by walking the input beam.
• Then, while IMC is locked and WFS loops are off, I aligned the beam spot on WFS heads to center it in DC (i.e. zeroing C1:IOO-WFS1_PIT_DC, C1:IOO-WFS1_YAW_DC, C1:IOO-WFS2_PIT_DC, C1:IOO-WFS2_YAW_DC)
• Then I ran C1:IOO-WFS_MASTER > Actiona > Correct WFS DC offsets script while keeping IMC locked (note the script says to keep it unlocked, but I think that moves away the beam). If we all agree this is ok, I'll edit this script.
• Then I checked the error signals of all WFS loops and still found that C1:IOO-MC_TRANS_PIT_OUTPUT and C1:IOO-MC_TRANS_YAW_OUTPUT have offsets. I relieved these offsets by averaging the input to these filter moduels for 100s and updating the offset. This is where I noticed that the PIT offset was wrong in sign.

WFS loops UGF tuning

• Starting with only YAW loops, I measured the open loop transfer functions (OLTFs) for each loop by simultaneously injecting gaussian noise from 0.01 Hz to 0.5 Hz using diaggui at the loop filter module excitation points and taking ration of IN1/IN2 of the filter modules.
• Then I scaled the YAW output matrix columns to get UGF of 0.1 Hz when YAW loop was along turned on.
• Then I tried to do this for PIT as well but it failed as even with overall gain of 0.1, the PIT loops actuate a lot of YAW motion causing the IMC to loose lock eventually.
• So I tried locking PIT loops along with YAW loops but with 0.1 overall gain. This worked for long enough that I could get a rough estimate of the OLTFs. I scaled the columns of PIT output matrix and slowly increased the overall gain while repeating this step to get about 0.1 Hz UGF for all PIT loops too.
• Note though that the PIT loop shape did not come out as expected with a shallower slope and much worse coherence for same amount of excitation in comparison to YAW loops. See attached plots.
• Never the less, I was able to reach to an output matric which works at overall gain of 1. I tested this configuration for atleast 15 minutes but the loop was working even with 6 excitations happening simultaneously for OLTF measurement.
• We will need to revisit PIT loop shapes, matrix diagonalization, and sources of noise.

OLTF measurements were done using this diaggui file. The measurement file got deleted by me by mistake, so I recreated the template. Thankfully, I had saved the pdf of the measurements, but I do not have same measurement results in the git repo.

I've turned off HEPA fan and all lights at:

PST: 2022-12-03 10:13:03.184705 PST
UTC: 2022-12-03 18:13:03.184705 UTC
GPS: 1354126401.184705

I took a transfer function measurement of the XEND PDH servo box, from servo input to piezo output [Attachment 1]. The servo gain knob was set to 10. The swept sine input was 50 mVpp, as to not saturate the servo components. I toggled the local boost on/off for these measurements. With the boost on, coherence was lost from ~100Hz-10kHz, and the saturation light indicators were flashing. I will retake this measurement shortly.

Atachment 2 is from a previous measurement of this PDH servo TF, found here. For this measurement, boost was off and the gain knob was set to 2.0. (If there is a more recent measurement than 2010, please point me to it.)

[Anchal, Paco]

We are doing this attempt again in following configuration:

• PSL shutter is closed. (So IR laser is free running)
• Beanote frequency between Y arm and Main laser is about 45 MHz.
• Green laser on Y end is locked. Transmission is above 1.1 (C1:ALS-TRY_OUT)
• All calibration oscillators are turned on and set to actuate ITMY. See screenshot attached.
• The calibration model was changed to demodulate the C1:ALS-BEATY_FINE_PHASE_OUT channel insteald. We'll have DQ channels before mixing with oscillator, after mixing, and also after applying a 4th order 30 Hz butterworth filter.

Start time:

PST: 2022-12-01 20:44:23.982114 PST
UTC: 2022-12-02 04:44:23.982114 UTC
GPS: 1353991481.982114
 

Stop time:

PST: 2022-12-02 14:32:29.547603 PST
UTC: 2022-12-02 22:32:29.547603 UTC
GPS: 1354055567.547603

I don't think you need to record the excitations. They are just sine waves. The amplitude you can read off from the OSC screen. You just have to have the BEAT channel recorded and you can demod it to get the calibration. If the BEAT channel is calibrated in Hz, and you know the 40m arm length, then you're all done.

[Paco]

I picked up the 950 nm laser that Koji tested before and restored the Jenne laser (may long it live).

I changed a couple of things; first I took out the old laser from the hose and noted the new laser has a shorter fiber patch cable, so I replaced the hose with a flexible fiber jacket I found around the X arm storage. I also added a 14 pin DIP socket so the laser is now always showing its part no. and is easy to install/uninstall. Last but not least I replaced the black insulating material right at the output of the laser package because it was decaying badly and spread a bunch of dusty residue all over the place. I used some foam instead.  See various attachments for visual support.

I was careful, testing the connections with a cheap LED to validate the setup before I connected the laser-- this made everything smooth and I finished the work by verifying the laser is outputting light at the other end of the fiber 1x2 coupler. The PD testing with Jenne's resucitated laser should proceed normally now.

RXA: Huzzah!!

After swapping out the HDD on donatella, I noticed that the display resolution was stuck on 700x400 and could not be changed. To fix this issue, I edited `/etc/apt/sources.list` to include the following:

deb http://ftp.us.debian.org/debian/ testing main non-free contrib
deb-src http://ftp.us.debian.org/debian/ testing main non-free contrib

to make `non-free` packages available in our repository, then I ran:

sudo apt-get update
sudo apt-get install firmware-amd-graphics

After the installation was complete, I did a reboot and the problem was fixed.

All incondescent lightsbulbs have been switched over to LED.

Many changes have been done to c1hpc to support dual demodulation at audio frequencies. We moved away with ASS style of lockin setup as the number of connections and screens required would become very large. Instead now, the demodulation is done for a selected oscillator, on a selected signal. Similarly, the demodulated signal can be further demodulated for another selected oscillator. Please familarize yourself with new screen and test the new model. The previous version of the model is kept as backup alogn with all it's medm screens, so nothing is lost. Shown as an example in the screenshot, AS1 and BS oscillators can be turned on, and BHDC_DIFF signal can be demodulated first with BS and next with AS oscillator to get the signal.