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ID Datedown Author Type Category Subject
  17328   Wed Nov 30 20:01:08 2022 ranaSummaryCalibrationSingle arm cal with 5 lines

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.



Basically, only the DARM line was recorded (DQ channs) so I modified the c1cal to store the SIG_OUT and DEMOD_I_IN1 channels for both BEATX and BEATY cal signals. This means I need to repeat this measurement. In the meantime I am also going to try and rerun calibrate the BEAT HZ transfer function.


  17327   Wed Nov 30 19:59:05 2022 ranaSummaryCalibrationSingle arm cal with 5 lines


YALS Hardware inspection

The ALS Cal for ITMY actuation was off by ~ 1000, so I decided I don't trust / understand what this beatnote is seeing. Then, I went in the lab to inspect things;

  1. ALS DFD and DEMOD: The demod box was off no perhaps on purpose, more likely by accident... the switch was off in the rear of the 1U box in the LSC rack... Also, the DB9 cable labeled ALS was disconnected. Fixed both these bugs and verified it worked all the way into cds.
  2. YARM Green injection: Did some re-alignment, and noted the mode was hopping a bit too much (once every couple of seconds) so I rotated the half waveplate before the green PZT steering mirrors by  ~ 8 deg and used the latter to get a GTRY transmission of > 0.320 (counts), about 75% more than last time. Finally I made sure the mode is robustly locked for several minutes.

Beatnote calibration

The factor above may be explained by the bogus signals coming into the beat fine phase channels on the ALS model. After locking the YARM with POY11, and locking the YAUX to the YARM cavity, I turned on the LSC oscillators -- all five of them see Attachment #1 for the screenshot -- and looked for the lines in the C1:ALS-BEATY_FINE_PHASE_OUT channel. Here, again the sensing output matrix was set up to actuate on ITMY, while the ETMY (control point of YARM loop) had all the output notches on. Once all lines were visible in the YAUX beatnote, I had to reduce the LSC filter gain from 0.012 to 0.011 to prevent loop oscillations... Then I recorded the gpstimes below with different conditions.

  • HEPA ON (JC Inside lab)
    • gpstime = 1352575798 to 1352576046
  • HEPA OFF (JC Inside lab)
    • gpstime = 1352576125 to 1352576216
  • HEPA OFF (JC in the control room)
    • gpstime = 1352576641 to 1352577591


Basically, only the DARM line was recorded (DQ channs) so I modified the c1cal to store the SIG_OUT and DEMOD_I_IN1 channels for both BEATX and BEATY cal signals. This means I need to repeat this measurement. In the meantime I am also going to try and rerun calibrate the BEAT HZ transfer function.


  17326   Wed Nov 30 18:27:07 2022 PacoUpdateGeneralMaking the Jenne laser great again


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.

  17325   Wed Nov 30 14:25:34 2022 TegaUpdateCDSAMD display driver installation

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.

  17323   Wed Nov 30 10:48:10 2022 JCConfigurationGeneralLED Instead of Incandescent Lights

All incondescent lightsbulbs have been switched over to LED.


Electrical came by today to see the lights. The issue may be the switches, but they will come by tomorrow to solve the issue. A couple light bulbs were noticed to be out, but they no longer have incandescent lights. . . only LED. I figured this would be preffered because of the reduction on noise. I would prefer to go ahead and ask to change all the incandescent bulbs to LED bulbs. Are there any objections to this?


  17322   Tue Nov 29 15:32:32 2022 AnchalUpdateBHDc1hpc model updates to support double audio dither

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.

  17321   Tue Nov 29 11:38:37 2022 JCHowToLSCLock Single Arm After MICH lock

I tried locking single arm this morning, but I was unable to because the triggers were set to lock strictly to MICH. Anchal explained this to me and helped me out. I figured this information would be useful and should be logged somewhere. In red, this is accessed through the IFO --> Configure. Choosing X Arm and Y Arm will change the triggers on the C1LSC page for the single arm locking (In the Black Box.) 

  17320   Mon Nov 28 20:14:27 2022 AnchalUpdateASCAS WFS proposed path to IMC WFS heads

In Attachment 1, I give a plan for the proposed path of AS beam into the IMC WFS heads to use them temporarily as AS WFS. Paths shown in orange are the existing MC REFL path, red for the existing AS path, cyan for the proposed AS path, and yellow for the existing IFO refl path.  We plan to overlap AS beam to the same path by installing the following new optics on the table:

  • M1 will be a new mirror mounted on a flipper mount reflecting 100% of AS beam to SW corner of the table.
  • M2 will be a new fixed mirror for steering the new AS beam path to match with MC WFS path.
  • M3 will be the existing beamsplitter used to pick off light for MC refl camera. We'll just mount this on a flipper so that it can be removed from the path. Precaution will be required to protect the CCD from high intensity MC reflection by putting on more ND filters.
  • The AS beam would need to be made approximately 1 mm in beam width. The required lenses for this would be placed between M1 and M2.

I request people to go through this plan and find out if there are any possible issues and give suggestions.

PS: Thanks JC for the photos. I got it from foteee google photos. It would be nice if these are also put into the 40m wiki page for photos of optical tables.

RXA: Looks good. I'm not sure if ND filters can handle the 1 W MC reflection, so perhaps add another flipper there. It would be good if you can measure the power on the WFS with a power meter so we know what to put there. Ideally we would match the existing power levels there or get into the 0.1-10 mW range.

  17319   Mon Nov 28 18:21:50 2022 PacoSummaryBHDBH44 prep

I checked the LSC rack to evaluate what we might need to generate 44 MHz rf in the hypothetical case we go from BH55 to BH44 (a.k.a. double RF demod scheme). There is an 11 MHz LO port labeled +16 dBm (measured 9 Vpp ~ 23 dBm actually) on the left hand side. Furthermore, there is an unused 55 MHz port labeled "Spare 55 LO". I checked this output to be 1.67 Vpp ~ +8.4 dBm. Anyways the 55 MHz doesn't look very nice; after checking it on the spectrum analyzer it seems like lower frequency peaks are polluting it so it may be worth checking the BH55 LO (labeled REFL 55) signal to see if it's better. Anyways we seem to have the two minimum LOs needed to synthesize 44 MHz in case we move forward with BH44.

[Paco, Yuta]

We confirmed the noisy 55 MHz is shared between AS55, BH55 and any other 55 MHz LOs. Looking more closely at the spectrum we saw the most prominent peaks at 11.06 MHz and 29.5 MHz (IMC and PMC nominal PM freqs). This 55 MHz LO is coming all the way from the RF distribution box near the IOO rack. According to this diagram, this 55 MHz LO should have gone through a bandpass filter; interestingly, checking the RF generation box spare 55 MHz the output is *cleaner* and displays ~ 17 dBm level... ??? Will continue investigating when we actually need this RF.

  17318   Mon Nov 28 16:58:20 2022 PacoUpdateCDSpypi package added

[Paco, Tega]

I added the pypi package "restoreEpics" to the donatella clone under test. This is required by some of Anchal's scripts that turn on F2A filters as well as other recovery stages during some measurements.

  17317   Mon Nov 28 16:53:22 2022 AnchalSummaryBHDF2A filters on LO1 LO2 AS1 and AS4

[Paco, Anchal]

I changed the script in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/outMatFilters/createF2Afilters.py to read the measured POS resonant frequencies stored in /opt/rtcds/caltech/c1/Git/40m/scripts/SUS/InMatCalc/resFreqs.yml instead of using the estimate sqrt(g/len). I then added Q = 3 F2A filters into FM1 output filter of LO1, LO2, AS1 and AS4 suspensions in anticipation of BHD locking scheme work.

  17316   Mon Nov 28 11:21:25 2022 JCUpdatePSLPMC input beam alignment

C1:PSL-PMC_PMCTRANSPD was increased from 0.72 to 0.731

  17315   Mon Nov 28 11:15:23 2022 AnchalUpdateCDSFront ends DAC Kill (DK) got activated; restored FEs

[Anchal, Paco, Yehonathan, JC]

Last night at 9:15 pm PST (Nov 27th, 2022) some kind of disruption happened to FEs. See attachment 1 to see the changes in FE state words of the IOP models. on c1lsc, c1sus and c1scex, change of 140 happend, that's 2nd, 3rd and 7th bit of the FE word was flipped, which I think is the TIM, ADC and DAC KILL (DK). When we came in morning, IMC suspensions were undamped and not responsive to coil kicks, vertex suspensions the same case, ETMX also same. The c1sus2 modelw as all in red.

To fix this, we restarted all rtcds models on all FEs by sshing into the computers and doing:

rtcds restart --all

Then we burt restored all models to 27th Nov, 3:19 am point doing following on rossa:

~>cd /opt/rtcds/caltech/c1/Git/40m/scripts/cds
cds (main)>./burtRestoreAndResetSUS.sh /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2022/Nov/27/03:19

Note: this issue was previously seen when fb1 was restarted without shutting down the FEs, and once when the martian switch was disrupted while FE models were running.

I'm not sure why this happened this time, what caused it at 9:15 pm yesterday, and why only c1lsc, c1sus and c1iscex models went to DAC KILL state. This disruption should be investigated by cds upgrade team.

  17314   Sun Nov 27 15:30:22 2022 ChrisUpdateOptimal ControlIMC alignment controller testing

Five more mode cleaner alignment controllers were tested this morning (remotely). These were designed to run in tandem with the standard controller, instead of supplanting it. Before the test, c1ioo was burt restored back to the settings of the previous test on Oct 28, and in MC TRANS PIT/YAW filter banks the 80 dB gain filters were disengaged and outputs were enabled. Subsequently, all settings were returned to the original values. 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 are the following:

  • musgo
    • OL start 1353602764
    • CL start 1353603074
    • policy start 1353603410
  • musgo_ghost
    • OL start 1353604697
    • CL start 1353605007
    • policy start 1353605355
  • musgo_stumble
    • OL start 1353606574
    • CL start 1353606884
    • policy start 1353607229
  • musgo_goldfish
    • OL start 1353608446
    • CL start 1353608756
    • policy start 1353609099
  • musgo_late
    • OL start 1353610321
    • CL start 1353610631
    • policy start 1353610971
  17313   Fri Nov 25 15:35:23 2022 AnchalUpdateSUSLow noise state

Turned off HEPA at:

PST: 2022-11-25 15:34:55.683645 PST
UTC: 2022-11-25 23:34:55.683645 UTC
GPS: 1353454513.683645

Turned on HEPA back at:

PST: 2022-11-28 11:14:31.310453 PST
UTC: 2022-11-28 19:14:31.310453 UTC
GPS: 1353698089.310453

  17312   Fri Nov 25 12:15:46 2022 AnchalUpdateVACVacuum Gate valves restored

I came today to find that PSL shutter was closed. I orginially thought some shimmer obersvations are underway in the quiet state. But that was not the case. When I tried to open the shutter, it closed back again indicating a hard compliance condition making it close. This normally happens when vacuum level is not sufficient, so I opened the vacuum screena dn indeed all gate valves were closed. This most probably happend during this interlock trip. So the main volume was just slowly leaking and reached to milli torr level today.

Lesson for future: Always check vacuum status when interlock trips.

[Paco, Anchal]

Paco came by to help. We went to asia (the Asus laptop at vacuum workstation) but could not open the medm or find the nfs mounted files. The chiara change did something and nfs mounted directories are not available on asia of c1vac. We rebooted asia and the nfs mount was working again. We can't simply restart c1vac because it runs acromag channels for vacuum system and needs to be done more carefully, a task for Monday.

After restarting asia, we opened the the vacuum control medm screen and followed the vaccum pump down instructions (mainly opening of the gate vales as the pumps were already on). Point to keep in mind, rule of thumb, do not open valve between a turbo pump and a volume if the pressure differential is more than 3 orders of magnitude. Saving turbo pumps is the priority.. Now the main volume is pumping down.

  17311   Thu Nov 24 15:37:45 2022 AnchalUpdateASCIMC WFS output matrix diagonalization effort

I tried following the steps and the method I was using converged to same output matrix upto 2 decimal points but there is still left over cross coupling as you can see in Attachment 1. With the new output matrix, WFS loop can be turned on with full overall gain of 1.


  • I switched off +20dB FM2 on C1IOO-WFS1_PIT and increased gain C1:IOO-WFS1_PIT_GAIN from 0.1 to 1 to be uniform with other filters.
  • Output matrix change:
    • Old matrix:
      -2.   4.8 -7.3
       3.6  3.5 -2. 
       2.   1.  -6.8
    • New Matrix:
      3.44  4.22 -7.29
      0.75  0.92 -1.59
      3.41  4.16 -7.21
  • I think the main change that allowed the WFS loop to become stable was the 0,0 element sign change.


  • I made overall gain C1:IOO-WFS_GAIN 0
  • Switched of (0:0.8) FM3 on PIT filter modules (IOO-WFS1_PIT, IOO-WFS2_PIT, IOO-MC2_TRANS_PIT)
  • Changed ramp time to 2 seconds on all these modules
  • Used offset of 10000 for WFS2 and MC2_TRANS, and 30000 for WFS1 (for some reason, response to WFS1 step was much lower than others)
  • Measured the following sensor channels
  • First I took 30s average of these channels, then applied the offsets in the three modules one by one and recorded steps in each sensor.
  • Measured step from reference value taken before, and normalized each step to the DOF that was actually stepped to get a matrix.
  • Inverted this matrix and multiplied with existing output matrix. Made sure column norm1 is same as before and column signs are same as before.
  • Repeated a few times.

Note: The standard deviation on the averages was very high even after averaging for 30s. This data should be averaged after low passing high frequencies but I couldn't find the filter module medm screens for these signals, so I just proceeded with simple averaging of full rate signal using cdsultis avg command.

Fri Nov 25 12:46:31 2022

The WFS loop are unstable again. This could be due to the matrix balancing done while vacuum was disrupted. The above matrix does not work anymore.

  17310   Thu Nov 24 11:23:35 2022 AnchalUpdateSUSLow noise state

I've turned off HEPA fan and all lights at
PST: 2022-11-24 11:23:59.509949 PST
UTC: 2022-11-24 19:23:59.509949 UTC
GPS: 1353353057.509949

c1ioo model has been updated to acquire C1:IOO-MC2_TRANS_PIT_OUT  and C1:IOO-MC2_TRANS_YAW_OUT at 512 Hz rate.

I'll update when I turn the HEPA on again. I plan to turn it on for a few hours everyday to keep the PSL enclosure clean.

Turned on HEPA again at:

PST: 2022-11-25 12:14:34.848054 PST
UTC: 2022-11-25 20:14:34.848054 UTC
GPS: 1353442492.848054

However this was probably not a low noise state due to vacuum disruption mentioned here.

  17309   Wed Nov 23 20:58:23 2022 yutaSummaryBHDBHD_DIFF sensitivity to BS dither with MICH Offset with different BH55 demodulation phases

[Anchal, Paco, Yuta]

Attachment #1 is the same plot as 40m/17303 but with MICH sensitivity for ASDC and AS55 also included (in this measurement, BH55 demodulation phase was set to 140.07 deg to minimize I fringe).
Y-axis is now calibrated in to counts/m using BS actuation efficiency 26.54e-9 /f^2 m/counts (40m/17285) at 311.1 Hz.
2nd X-axis is calibrated into MICH offset using the measured AS55_Q value and it's MICH sensitivity, 8.81e8 counts/m (this is somehow ~10% less than our usual value 40m/17294).
ASDC have similar dependence with BHDC_SUM on MICH offset, as expected.
AS55_Q have little dependence with MICH offset on MICH offset, as expected.

This plot tells you that even a small MICH offset at nm level can create MICH sensitivity for BHDC_DIFF, even if we control LO phase to have BH55_Q to be zero, as MICH offset shifts zero crossing of BH55_Q for LO phase.

Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/BHD/BH_DIFFSens_pydemod.ipynb

Attachment #2 is the same plot, but BH55 demodulation phase was tuned to 227.569 deg to have no MICH signal in BH55_Q (a.k.a measurement (c)).
In this case, LO phase will be always controlled at 0 deg (90 deg away from optimal), even if we change the MICH offset, as BH55_Q will not be sensitive to MICH.
In this plot, BHD_DIFF have little sensitivity to MICH, irrelevant of MICH offset, as expected.
MICH sensitivity for BH55_I is also constant, which indicate that LO phase is constant over this measurement, as expected.

Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/BHD/BH_DIFFSens_pydemod.ipynb

Attachment #3 is the same plot, but BH55 demodulation phase was tuned to 70 deg.
This demodulation phase was tuned within 5 deg to maximize MICH signal in BHD_DIFF with large MICH offset (20).
In this case, LO phase will be always controlled at 90 deg (optimal), even if we change the MICH offset, as BH55_Q will not be sensitve to LO carrier x AS sideband component of the LO phase signal.
In this plot, BHD_DIFF have high sensitivity to MICH, irrelevant of MICH offset (at around zero MICH offset it is hard to see because LO_PHASE lock cannot hold lock, as there will be little LO phase signal in BH55_Q, and measurement error is high for BHD_DIFF and BH55 signals).
MICH sensitivity for BH55_I and BH55_Q is roughly constant, which indicate that LO phase is constant over this measurement, as expected.

These plots indicate that BH55 demodulated at MICH dither frequency can be used to control LO phase robustly at 90 deg, under unknown or zero MICH offset.

Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/BHD/BH_DIFFSens_pydemod.ipynb

LO phase delay:
 From these measurements of demodulation phases, I guess we can say that phase delay for 55 MHz in LO path with respect to MICH path (length difference in PR2->LO->BHDBS and PR2->ITMs->AS->BHDBS) is

2*(227.569-70(5)-90)-90 = 45(10) deg

 This means that the length difference is (omegam=5*2*pi*11.066195 MHz)

c * np.deg2rad(45(10)+360) / omegam = 6.1(2) m   (360 deg is added to make it close to the design)

  Is this consistent with our design? (According to Yehonathan, it is 12.02 m - 5.23 m = 6.79 m)

  Attachment #4 illustrates signals in BH55.

 - Lock LO PHASE with BH55 demodulated at MICH dither frequency (RF+audio double demodulation), and repeat the same measurement
 - Finer measurement at small MICH offsets (~1nm) to see how much MICH offset we have
 - Repeat the same measurement with BH55_Q demodulation phase tuned everytime we change the MICH offset to maximize LO phase sensitivity in BH55_Q (a.k.a measurement (b)).
 - What is the best way to tune BH55 demodulation phase?

  17308   Wed Nov 23 17:28:39 2022 YehonathanUpdateBHDSome more calculations

Fields at the BHD BS. More on this later.

  17307   Wed Nov 23 17:21:44 2022 JCUpdateVACInterlocks may have been tripped due to N2 pressure loss

[Paco, JC]

While changing out one of the N2 tanks today, one of the fitting stripped. This caused a major loss of pressure. I replaced one fitting then realized there was a second leak around the area of the gauge. Paco and I changed this and everything should be back up and running. Thhe interlocks may have been tripped  within the last 2 hours.


  17306   Wed Nov 23 17:12:34 2022 RadhikaUpdateALSXARM green laser lock debugging

I tested the mixer by feeding it a 300 kHz signal sourced from a Moku:Go. I kept the LO input the same - 231.25 kHz from the signal generator. The mixer output was a ~70 kHz waveform as expected, so demodulation is not the issue in green locking.

Next I'll align the arm cavities with IR and check to see if the green REFL signal looks as expected. If not, we'll have to invesitage the REFL PD. If the signal looks fine, and we now know it's being properly demodulated, the issue must lie further downstream.

  17305   Wed Nov 23 16:34:33 2022 KojiUpdateCDSNew donatella testing

Let's use this entry to list of the test results of new donatella.

  • Firefox - OK (typing elog now)
  • sitemap - OK
  • Diaggui (DTT) looks working fine for the current and past data
  • Dataviewer looks working fine for the current and past (slow/fast) data
  • ndscope - fine
  • foton - works fine
  • burtgooey - ?
  17304   Wed Nov 23 16:12:00 2022 TegaUpdateCDSI/O chassis parts inventory II

[Tega, JC]

We picked up the following I/O chassis components from Downs CDS testing lab:

Components Quantity
I/O chassis timing interface (missing aLIGO Duotone to IO interface adapter board) 1
Digital I/O PCI Express card 16ch/16ch 1
Adnaco PCI Express Gen 2 Extension System 1
PCIe x4 host interface board 6
OSS expansion Link board x4 1
OSS expansion Link board x4/x8 Gen2 3
aLIGO 16-Bit DAC Adapter board 1
aLIGO 18-Bit DAC Adapter board 12
GSC PMC-PCI adapter board 11
GSC PCIe-PMC adapter board 2
Avago LC transceiver (HFBR-57E0PZ) 9
  17303   Wed Nov 23 14:59:11 2022 PacoSummaryBHDBHD_DIFF sensitivity to BS dither with MICH Offset

[Yuta, Paco, Anchal]

We measured

(a) BHDC_DIFF sensitivity to BS dither for a set of MICH offsets.


  • MICH locked with AS55_Q
    • The MICH offset was varied below
  • LO_PHASE locked with BH55_Q
    • Balanced DCPD_A and DCPD_B by applying a digital gain of 1.00 to DCPD_A
    • Changed the BH55 demod angle to 140.07 deg to minimize BH55_I
  • BS dither at 311.1 Hz
    • Use newly added HPC_BS Lockins to readback the demodulated signals

Results & Discussion

The analysis was done with the '/cvs/cds/rtcds/caltech/c1/Git/40m/scripts/CAL/BHD/BHD_DIFFSensitivity.ipynb' notebook.

Attachment #1 shows the main result showing the sensitivity of various demodulated error signals at 311.1 Hz for a set of 21 MICH offsets. We noted that if we didn't randomize the MICH offset scan, we observed a nonzero "zero crossing" for the offset.
Note that, although LO_PHASE loop was always on to control the LO phase to have zero crossing of BH55_Q, actual LO phase is not constant over the measurement, as MICH offset changes BH55_Q zero crossing.
When MICH offset is zero, LO_PHASE loop will control the LO phase to 0 deg (90 deg away from optimal phase), and BHDC_DIFF will not be sensitive to MICH, but when MICH offset is added, BHDC_DIFF start to have MICH sensitivity (measurement is as expected).
For BHDC_SUM, MICH sensitivity is linear to MICH offset, as it should be the same as ASDC, and does not depend on LO phase (measurement is as expected).
For BH55_Q, MICH sensitivity is maximized at zero MICH offset, but reduces with MICH offset, probably because LO phase is also being changed.

  17302   Wed Nov 23 12:58:33 2022 YehonathanUpdateBHDSome more calculations

Changed the BHD BS transmissivity to 0.56.

Demodulation Phases

As was noted before. The LO phase sensitivity plot vs LO phase from the previous elog shows the optimal sensitivity at each LO phase. That means that the optimal demodulation phase might change as a function of LO phase. Attachment 1 shows the previous plot and a plot showing the optimal modulation phase for some of the methods. When double demodulation is involved I optimize one modulation and show the optimal demodulation angle of the second. As can be seen, optimal audio demodulation angles don't change as a function of LO phase.

Additionally, as expected maybe, for the single RF sideband methods that nominally should not have worked at nominal LO phase (angle in which BHD Diff is most sensitive to MICH), the optimal demodulation angle changes quite a bit around the nominal LO phase.

Fixed demodulation angle

Attachment 2 shows the LO phase sensitivity in the single 55MHZ sideband method when we fix the demodulation angle. -23.88 is the demod angle optimal for nominal LO phase. 66.12 is 90 degrees away from that. -75.21 is the is the demod angle optimal for LO phase at the amplitude quadrature and 14.78 is 90 degrees away from that. It can be seen that fixing the demod angle can be mostly harmless.

Effect of MICH offset

The simulations were run with 0 MICH offset. Attachment 3 shows the LO phase sensitivity of the different methods when MICH offset is introduced together with the optimal demod angle. As expected the single RF SB methods are sensitive to this offset while the double demod methods are not since they are not relying on DC fields.


[Yehonathan, Yuta, Paco]

We would like to estimate:

  • LO phase sensitivty (for RF55 + audio dither scheme), as a function of RF demod angle (both I and Q); not to be confused with audio dither angle.
  • LO phase sensitivity (for all schemes like in Attachment #2 of this previous post) but with some nonzero MICH offset.
  • LO phase sensitivity (for RF55 + audio dither scheme) but with the uBHDBS (44:56) values from this post.


  17301   Wed Nov 23 11:06:08 2022 AnchalUpdateBHDc1hpc and c1sus modified to add BS dither and demodulation option

c1hpc has option of dithering BS now (sending excitation to BS LSC port to c1sus over IPC). This is available for demodulating BHDC and BH55 signals. Also BS is a possible feedback point, however, we would stick to using LSC screen for any MICH locking.

c1sus underwent 2 changes. All suspension models were upgraded to the new suspension model (see 40m/16938 and 40m/17165). Now the channel data rates are set in simulink model and activateDQ script is not doing anything for any of the suspension models.

  17300   Tue Nov 22 20:46:11 2022 RadhikaUpdateALSXARM green laser lock debugging

[Paco, Anchal, Radhika]

We tried to debug why the XARM green laser isn't catching lock with the arm cavity. First I tried to improve alignment:

- Aligned the arm cavity axes by maximizing IR transmission.

- Adjusted M1 and M2 steering mirrors to align the X green beam into the arm. GTRX reached ~0.3.

     - At the vertex table, I adjusted the lens in the GTRX path to focus the beam onto the DCPD. This increased GTRX to ~0.7.

- Visually I confirmed that TEM00 of the green laser was flashing in the arm cavity, fairly centered. But it was not catching lock.

We suspected the XARM AUX PZT might be damaged/unresponsive. Paco, Anchal, and I fed several frequency signals to the PZT and looked for a peak in the AUX-PSL beatnote spectra at the expected frequency. We confirmed that the X-arm AUX PZT is responsive up to 12 kHz (limited by ADC samping rate). We have no reason to suspect the PZT wouldn't be responsive at the PDH modulation frequency of 231 kHz.

Next steps:

- Investigate PDH servo box / error signal.

  17299   Tue Nov 22 15:33:02 2022 TegaUpdateCDSI/O chassis parts inventory

[Tega, JC]

We received the following I/O chassis parts from LLO:

Components Quantity
Timing Master 1
I/O chassis timing interface 8
I/O chassis backplane board 18
I/O chassis motherboard 20
M4 power supply 36


  17298   Tue Nov 22 10:29:31 2022 AnchalSummarySUSITMY Coil Strengths Balanced

I followed this procedure to balance the coil strengths on ITMY. The position sensor was created by closing PSL shutter so that IR laser is free running, and locking the green laser to YARM, this makes C1:ALS-BEATY_FINE_PHASE_OUT a position sensor for ITMY. The oplev channels C1:SUS-ITMY_OL_PIT_IN1 and C1:SUS-ITMY_OL_YAW_IN1 were used for PIT and YAW sensors. Everything else followed the procedure. The coil gains were changed as follow:

C1:SUS-ITMY_ULCOIL_GAIN :   1.036 -> 1.061
C1:SUS-ITMY_URCOIL_GAIN : -1.028 -> -0.989
C1:SUS-ITMY_LRCOIL_GAIN :   0.930 -> 0.943
C1:SUS-ITMY_LLCOIL_GAIN : -1.005  -> -1.007

I used this notebook and this diaggui to do this balancing.

  17297   Tue Nov 22 08:56:27 2022 JCUpdatePSLPMC input beam alignment

[Paco, Anchal, JC]

C1:PSL-PMC_PMCTRANSPD ~ 0.715 this morning, this was increased to ~0.730. There also seems to be an earthquake going on and the MC is flashing.

  17296   Mon Nov 21 18:43:46 2022 yutaUpdateBHDc1hpc and c1lsc modified to send BHD_DIFF and BHD_SUM

[Anchal, Yuta]

To send BHD signals from c1hpc after unwhitening and taking sum/diff, c1hpc and c1lsc models are modified.
PDDC_DOF_MTRX medm screen was modified to reflect this change.
We don't need to unwhiten and take sum/diff again in c1lsc model anymorewink

  17295   Mon Nov 21 18:33:05 2022 AnchalUpdateSUSMC2 OSEMs calibrated using MC_F

Repeated this for MC2 using the error measurement technique mentioned in 40m/17286 using this notebook. Following are the cts2um gain changes:

UL: 0.30408 -> 0.415(47)
UR: 0.28178 -> 0.361(39)
LR: 0.80396 -> 0.782(248)
LL: 0.38489 -> 0.415(49)

I averaged 19 samples to get these values hoping to have reached systematic error limit. The errors did not change from a trial with 9 samples except for the LR OSEM.
  17294   Mon Nov 21 17:44:00 2022 yutaSummaryBHDMICH BHD displacement sensitivity with AS55_Q and BHD_DIFF

[Paco, Yuta]

MICH displacement sensitivity was compared under AS55_Q locking and BHD_DIFF locking.
Sensitivity with BHD was better by more than an order of magnitude due to smaller sensing noise.
During the measurement, LO phase fluctuation was ~13 deg RMS.

Locking configurations:
 - MICH was first locked with AS55_Q, no offset, and then handed over to BHD_DIFF after LO phase locked. FM2, FM3, FM4, FM5, FM6, FM8, FM10 on, C1:LSC-MICH_GAIN=-3 gave UGF of around 80 Hz.
 - LO PHASE was locked with BH55_Q, no offset. FM5, FM8 on, C1:HPC-LO_PHASE_GAIN=-2 feeding back to LO1 gave UGF of around 40 Hz.
 - Attachment #1 shows the OLTFs.

Sensitivity estimate:
 - Sensitivity was estimated using measured actuator gains and optical gains. Following numbers are used.

C1:LSC-AS55_Q_ERR to MICH 1.08e-9 counts/m (measured at 311.1 Hz today)
C1:HPC-BHDC_DIFF to MICH 1.91e-9 counts/m (measured at 311.1 Hz today)
BS   : 26.54e-9 /f^2 m/counts (40m/17285)
LO1  : 26.34e-9 /f^2 m/counts (40m/17285)

 These numbers were also reflected to C1:CAL-MICH_CINV and C1:CAL-MICH_A.
 C1:CAL-MICH_A_GAIN = 0.5 was used to take into account of LSC output matrix of MICH to BS being C1:LSC-OUTPUT_MTRX_8_2=0.5.

 - Attachment #2 shows the displacement spectrum of MICH (top) and LO PHASE (bottom). Brown MICH curve is when locked with AS55_Q and black MICH curve is when locked with BHD_DIFF. RMS of original and in-loop LO PHASE was estimated to be

 Original LO phase noise: 393 nm RMS (266 deg RMS)
 In-loop LO phase noise: 19.4 nm RMS (13 deg RMS)

 - Improve LO phase loops to reduce LO phase noise
 - Estimate LO phase noise contribution to MICH sensitivity

  17293   Mon Nov 21 15:16:12 2022 TegaUpdateCDSworkstation upgrade

We are currently working on donatella workstation upgrade, which we are calling donatellaclone for now. After installing Debian 11, we install the cds conda environment. This takes care of most of the requisite packages except `dataviewer` and `burtgooey`.

To resolve the machines on the martian network, we do the following:

sudo apt update

sudo apt install resolvconf

then create or open the file '/etc/resolvconf/resolv.conf.d/head'

sudo nano /etc/resolvconf/resolv.conf.d/head

and add the following



search martian



The installation binary for burtgooey `/usr/bin/burtgooey` is a symoblic link that points to `/ligo/apps/epics-3.14.10/extensions/bin/linux-x86_64/burtgooey`. To get this working, we need to install some requisite libraries, see below:

sudo apt-get install libxm4

wget -c http://archive.ubuntu.com/ubuntu/pool/main/g/glibc/multiarch-support_2.27-3ubuntu1_amd64.deb

sudo dpkg -i multiarch-support_2.27-3ubuntu1_amd64.deb

wget -c http://ftp.debian.org/debian/pool/main/g/glibc/multiarch-support_2.28-10+deb10u1_amd64.deb

sudo dpkg -i multiarch-support_2.28-10+deb10u1_amd64.deb

wget -c https://apt.ligo-wa.caltech.edu:8443/debian/pool/bullseye/libxp6/libxp6_1.0.2-2_amd64.deb

sudo dpkg -i libxp6_1.0.2-2_amd64.deb

wget -c http://ftp.debian.org/debian/pool/main/r/readline6/libreadline6_6.3-8+b3_amd64.deb

sudo apt-get install -y libtinfo5

sudo dpkg -i libreadline6_6.3-8+b3_amd64.deb

sudo add-apt-repository universe

sudo apt-get install libncurses5



dataviewer depends on 'grace' and 'libmotif-dev' which are not installed automatically and results in a broken initial installation, so do the following:

sudo apt-get install dataviewer

sudo apt --fix-broken install


  17292   Mon Nov 21 14:55:58 2022 JCConfigurationGeneralLED Instead of Incandescent Lights

Electrical came by today to see the lights. The issue may be the switches, but they will come by tomorrow to solve the issue. A couple light bulbs were noticed to be out, but they no longer have incandescent lights. . . only LED. I figured this would be preffered because of the reduction on noise. I would prefer to go ahead and ask to change all the incandescent bulbs to LED bulbs. Are there any objections to this?

  17291   Mon Nov 21 11:52:50 2022 RadhikaSummaryCalibrationSingle arm cal with 5 lines

[Paco, Radhika]

We set out to realign the YARM AUX laser input into the arm cavity.

- We noticed that the GTRY beam was way off the center of the screen, so we went to the vertex table to align the camera.

- The beam spot at GTRY PD was large/divergent, so we shifted the PD closer to the penultimate mirror. We also doubled the PD gain. Transmission went from ~0.3 to ~0.7 (with gain doubled).

- We returned to the YARM end table to finalize alignment with the green PZT steering mirrors. GTRY was maximized to ~0.77.

  17290   Mon Nov 21 09:13:31 2022 JCUpdatePSLPMC input beam aligned again, IMC

[JC, Paco]

I attempted to align PMC Beam from a transmission of 0.72. I failed to do so on my own, but Paco arrived and helped me out. Transmission has gone from from 0.72 to ~0.73.

  17289   Sun Nov 20 13:42:21 2022 AnchalUpdateSUSIMC test

I repeated this test for the following configuration:

  • PSL shutter closed at good IMC transmission
  • Offset value of 14000 written to C1:IOO-MC_TRANS_SUM_FILT_OFFSET
  • WFS loops ON but ASCPIT outputs of the optics were turned off.

The test ran for 4000 seconds between following timestamps:

start time: 1352878206
stop time: 1352882207

This script was used to run this test and can be used again in future to repeat the same test.

  17288   Fri Nov 18 23:21:54 2022 ranaUpdateASCIMC WFS ongoing

On Wednesday, I did some rework of the MC WFS gains. I think it should still work as before as long as the overall input gain is set to 0.1 (not 1.0 as the button on the screen sets it to).

  1. The MC_TRANS P/TY signals were very small because they are normalized by the SUM. I added a '+80 dB' gain filter to the MC2_TRANS_PIT and MC2_TRANS_YAW filter banks which increase the signal gain before the digital signals are sent from the MC2 model to the MC_WFS control screen's Input Matrix. Now if you plot the MC_TRANS and WFS signals on dataviewer, the time series all have roughly the same magnitude.
  2. I put a "-80 dB" gain button into the MC2_TRANS servo filter banks. This should make it have the same overall gain as before, since the (sensor to servo) Input Matrix is diagonal.
  3. The servo gains (WFS1_PIT, WFS2_YAW, etc.) had some negative signs. To make all the servo gains positive, I moved those signs into the Output Matrix.
  4. The Output Matrix had some values with 4-5 significant digits. I think its not necessary to have more than 2 places after the decimal point since out measurements are not that accurate, so I rounded them off. We can/should change that screen to reduce the PREC field on the matrix element display.
  5. Now, if the overall INPUT_GAIN slider is increased beyond 0.1, there is some pitch oscillation. I think that is happening because the Output Matrix is not that great. In principle, if we have diagonalized the system, putting offsets into the various loops' error points won't make offsets in the other loops, but this is not the case. The pitch loops have a lot of cross coupling (my guess is that the off-diagonal elements are of order 0.1); the yaw loops are several times better. I suggest someone redo the Output Matrix diagonalization and then use the error point offset method to check that they are diagonal.

We mainly want these loops to work well at DC, so it is perhaps better if we can measure the matrix at DC. Its less automatic than at 13 Hz, but I think it could be done with a script and some iterative matrix inversion:

  1. IMC locked, IMC ASC loops all open (by setting the overall input gain slider to zero)
  2. apply an offset in the WFS1_P basis (turn off the integrators in all the servo loops, and apply a ~400 count offset in the error point)
  3. tweak the WFS1_P output matrix until the WFS2_P and MC2_TRANS_P signals go to zero.
  4. repeat for all 6 loops.

I haven't tried this procedure before, but I think it should work. You can use something like "cdsutils servo" to slowly adjust the Output Matrix values.


  17287   Fri Nov 18 22:46:02 2022 yutaSummaryBHDMICH optical gain measurements with different LO phases, with signs

MICH optical gain with a sign was measured with different LO phases over ~180 degrees, with updated calibration and higher MICH UGF.
Zero crossing of BH55_Q_ERR seems to be 68 degrees away from optimal LO phase.

Calibrated sensing matrix:
 - Locked MICH with AS55_Q at dark fringe, with UGF of ~200 Hz. Notch at 311.1 Hz was turned on.
 - Locked LO PHASE with BH55_Q, with UGF of ~10 Hz (C1:HPC-LO_PHASE_GAIN=-2, using LO1).
 - Measured the sensing matrix as written in 40m/17279, but with different dither frequencies to avoid violin mode frequencies and to match with already-installed notch filters.
 - Sensing matrix was calibrated into meters using actuator gains measured in 40m/17285
 - Sign was added by comparing the phase with C1:SUS-xx_LSC_OUT. If they are 90-270 deg apart, minus sign was added to the sensing matrix.
 - Resuts are as follows. At least important green ones are consistent with previous measurements (40m/17279).

Calibrated sensing matrix with the following demodulation phases (counts/m)
{'AS55': -164.1726747789845, 'BH55': 169.57651332419115}
      Sensors            MICH @311.1 Hz           LO1 @147.1 Hz           AS1 @141.79 Hz           
C1:LSC-AS55_I_ERR_DQ    2.72e+06 (84.89 deg)    6.41e+05 (14.60 deg)    -1.98e+05 (206.79 deg)    
C1:LSC-AS55_Q_ERR_DQ    -1.20e+09 (-228.85 deg)    -1.43e+06 (-106.51 deg)    1.41e+06 (29.21 deg)    
C1:LSC-BH55_I_ERR_DQ    -2.45e+09 (-230.64 deg)    -6.57e+07 (167.84 deg)    7.28e+07 (-16.56 deg)    
C1:LSC-BH55_Q_ERR_DQ    7.81e+09 (-48.64 deg)    -7.34e+08 (159.70 deg)    8.06e+08 (-10.08 deg)    
C1:HPC-BHDC_DIFF_OUT    -9.91e+08 (-224.55 deg)    -1.13e+08 (164.14 deg)    1.26e+08 (-3.95 deg)    
C1:HPC-BHDC_SUM_OUT    -6.84e+06 (-104.69 deg)    1.50e+07 (-8.71 deg)    -1.79e+07 (173.80 deg)    
LO phase from C1:LSC-BH55_Q_ERR_avg 4.98e-03 +/- 1.65e+01 deg

Estimating LO phase:
 - Using 7.34e+08 counts/m, which is an optical gain of BH55_Q for LO1, LO phase can be estimated as follows.

A = BH55optgain*lamb/(4*pi) = 62 counts
LOphase = arcsin(BH55_Q/A)

 - When C1:HPC-LO_PHASE_GAIN is plus, LOphase was calculated with the following to take into account of the sign flip in the controls.

LOphase = 180 - arcsin(BH55_Q/A)

Balancing A-B:
 - BHDC_A and BHDC_B were balanced to give null MICH signal in BHDC_SUM at 311.1 Hz. This gave BHDC_DIFF = 0.919*A - B.
 - It seems like this balancing gain changes over time by ~30%.

 - Attachment #1 is uncalibrated MICH optical gain in different LO phases, and Attachment #2 is the calbirated one. Basically the same with 40m/17282, but with updated calibration and sign considerations.
 - In addition to the previous measurements, we can see that BHD_SUM is not dependent on LO phase (small dependence probably from not perfect A and B balancing).
 - 0 deg of LO phase means that it is a zero crossing of BH55_Q with a slope that LO PHASE loop can be closed with a minus C1:HPC-LO_PHASE_GAIN, feeding back to LO1.
 - Dotted and dashed gray lines are from scipy.optimize.curve_fit using the following fitting function (not an eyeball fit this time!).

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

 - Fitting results show that we are -22 deg away from our intuition that BH55_Q crosses zero when BHDC_DIFF give no MICH signal (68 degrees away from optimal LO phase).
 - Fitting results also show that BH55_Q sensitivity to MICH crosses zero when BHD_DIFF sensitivity to MICH maximizes. This suggests that BH55+MICH dither can be used to lock LO phase to optimal LO phase.

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

 - Compare with expected values from simulations
 - Why do we have -22 deg?
   - Check if there is any RAM in 55 MHz in the input beam by measuring AM with ITM single bounce (quick measurement shows it is small)
   - Unbalanced BHD BS?
   - Contribution from 55 MHz sidebands from LO beating with 55 MHz sidebands from AS?
       - Lock LO phase using audio dither only (demodulate BHDC_DIFF?).

  17286   Fri Nov 18 17:00:15 2022 AnchalUpdateSUSMC1 and MC3 OSEMs calibrated using MC_F

After the MC1 osem dewhitening was fixed, I did the calibration of MC1 OSEM signals using MC_F using this notebook. A 0.1 Hz oscillation with amplitude of 1000 cts was sent to MC1 lockin2 and was kept on between 1352851381 and 1352851881. Then I read back the data from DQ channels and performed a welch with standard deviation calculation from the different segments used. From this measurement, I arrive to the following cts2um gain values that were changed in MC1 filter file. The damping remained stable after the changes:

UL: 0.09 -> 0.105(12)
UR: 0.09 -> 0.078(9)
LR: 0.09 -> 0.065(7)
LL: 0.09 -> 0.087(10)

I followed the same method for MC3 as well to get mroe meaningful error bars. This measurement was done between 1352856980 and 1352857480 using this notebook. Here are the changes made:

UL: 0.39827 -> 0.509(57)
UR: 0.33716 -> 0.424(48)
LR: 0.335 -> 0.365(40)
LL: 0.34469 -> 0.376(43)

The larger error bars could be due to more noisy MC3 osem outputs as the satellite amplifier gain is lower here.

  17285   Fri Nov 18 16:58:39 2022 yutaSummaryBHDActuator calibrations for MICH BHD

As there is some confusion in actuator calibration, we have done the measurement again from scratch.
Results are the following.
New values for LO1, LO2, AS1, AS4 are obtained from free swinging ITMY-LO, so it should be more robust.

BS   : 26.54e-9 /f^2 m/counts
ITMX :  4.93e-9 /f^2 m/counts
ITMY :  4.90e-9 /f^2 m/counts
LO1  : 26.34e-9 /f^2 m/counts
LO2  :  9.81e-9 /f^2 m/counts
AS1  : 23.35e-9 /f^2 m/counts
AS4  : 24.07e-9 /f^2 m/counts

BS, ITMX, and ITMY actuator calibration:
 Followed the procedure in 40m/16929.
 Calibrated AS55_Q using X-Y plot to be 9.72e8 counts/m (Attachment #1), locked MICH with UGF of 10 Hz, and measured the transfer function from C1:LSC-BS,ITMX,ITMY_EXC to C1:LSC-AS55_Q_ERR.
 The result is Attachment #2. They are consistent with 40m/16929.

LO1, LO2, AS1, and AS4 actuator calibration:
 Followed similar steps with ITMY-LO fringe.
 Calibrated BH55_Q using X-Y plot to be 7.40e9 counts/m (Attachment #3), locked ITMY-LO with UGF of ~15 Hz (Attachment #4), and measured the transfer function from C1:SUS-LO1,LO2,AS1,AS4_LSC_EXC to C1:LSC-BH55_Q_ERR.
 The result is Attachment #5. They are inconsistent with 40m/17284, but this one should be more robust (see discussions below).

LO1, LO2, AS1, and AS4 actuator calibration by taking the ratio between ITMY:
 We have also followed the steps in 40m/17206 to calibrate BHD actuators.
 This method does not depend on BH55_Q optical gain calibration, but depends on ITMY calibration.
 Measured OLTFs for ITMY-LO fringe locking is Attachment #6, and actuator ratio with respect to ITMY is Attachment #7. In this measurement, Bandstop filter at 96.7 Hz for AS4 was turned off, and gain was lowered by a factor of 2 to avoid AS4 oscillating.
 This gives

LO1  : 116.81e-9 /f^2 m/counts
LO2  :  51.69e-9 /f^2 m/counts
AS1  : 101.48e-9 /f^2 m/counts
AS4  : 117.84e-9 /f^2 m/counts

 These are not consistent with 40m/17284, and larger by a factor of ~2-3.
 These are also not consistent with the values from free swinging measurement, and are larger by a factor of ~4-5.
 I guess there are some gains missing when comparing ITMY loop in c1lsc and other loops in c1hpc.

  17284   Fri Nov 18 13:05:00 2022 yutaSummaryBHDGains adjusted for bandstop filters for BHD optics

[Paco, Yuta]

We realized that bandstop filters ("violin" filters) we implemented in 40m/17206 had pass band gain of -1dB.
gain(1,"dB") was added to all the filters (see Attachment #1 for gain adjusted violin filters for AS1).
We also realized that audio dither frequency we chose to generate BH55+audio dither error signal and to measure sensing matrix at ~280 Hz was too close to violin filters.
These will affect calibrations by upto ~60%.
For example, actuation gains should be actually

  • LO1 = 3.14e-8 / f^2 m / cts * 3dB = 4.44e-8 / f^2 m / cts (3 violin filters)
  • LO2 = 2.52e-8 / f^2 m / cts * 0dB = 2.52e-8 / f^2 m / cts (no violin filters)
  • AS1 = 3.14e-8 / f^2 m / cts * 3dB = 4.44e-8 / f^2 m / cts (3 violin filters)
  • AS4 = 2.38e-8 / f^2 m / cts * 4dB = 3.36e-8 / f^2 m / cts (3 violin filters+ bandstop at 96.7 Hz)

 - Redo actuator calibrations for LO1, LO2, AS1, AS4
 - Redo sensing matrix measurements with different audio dither frequencies for LO1 and AS1

  17283   Fri Nov 18 09:00:27 2022 JCUpdateVACPressure Gauge Information

I bought the spare Full-Range Pirani Gauge a while ago and realized that I never logged this. The Pirani Gauges we are using is described below.

QTY Product Description Serial No.


I purchased this gauge from Agilent through TechMart. The spare is located inside the Vac Equipment cabinet (The only brown cabinet.) along the X-Arm.

  17282   Thu Nov 17 20:02:10 2022 yutaSummaryBHDMICH optical gain measurements with different LO phases

MICH optical gain was measured with different LO phases over ~90 degrees.
Zero crossing of BH55_Q_ERR seems to be roughly 55 degrees away from optimal LO phase.

What we did:
 - Locked MICH with AS55_Q with no offset, with UGF at ~10 Hz (same as configuration in 40m/17279).
 - Injected BS calibration line at amptilude of 300 counts at 211.1 Hz.
 - Locked LO Phase with BH55_Q with different offsets added at C1:HPC-LO_PHASE_OFFSET.
 - Measured sensing matrix at that frequency. Counts are calibrated into meters using actuator efficiencies as described in 40m/17279.
 - LO phase was obtained using a DC value of BH55_Q. This was calibrated into degrees from the following:

Amplitude of LO-AS fringe in BH55_Q was calculated to be

A = BH55optgain*lamb/(4*pi) = 60 counts

where BH55optgain is 7.12e8 counts/m, which is optical gain of BH55_Q for LO1 measured in 40m/17279.
(Actually, BH55_Q goes upto ~ +/-200 counts in time series data, but maybe 60 is the nominal fringe amplitude, considering alignment fluctuations and fluctuation in AS darkness? Note that, no offset in BH55_Q is assumed in this calculation, but AM etc can create an offset.) 
LO phase can be obtained by

LOphase = arcsin(BH55_Q/A)

where BH55_Q a DC value (10 sec average) of BH55_Q.

 Attachment #1 is uncalibrated plot C1:HPC-LO_PHASE_OFFSET of around +/- 50 was the maximum we could add, and more offset gave unstable lock.
 Attachment #2 is calibrated plot. AS55_Q does not depend on LO phase, as expected. BH55_Q and BHDC_DIFF depend on LO phase as expected. BH55_I and AS55_I stay at low level, as expected (this means that our RF demodulation phase is OK).
 Dotted gray line is an eyeball fit of expected curve (40m/17170) to fool your eyes.
 This tells you that we are roughly 55 deg away from LO phase which gives maximum MICH signal for BHDC_DIFF.
 Error bar in x-axis is from standard deviation of BH55_Q fluctuations. Error in y axis is probably ~20% at maximum.
 Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/SensingMatrix/MeasureSensMatBHD.ipynb

 - Repeat the measurement with
   - MICH locked with higher UGF, with notch at 211.1 Hz, for more robust AS dark fringe
   - DCPD A and B balanced at 211.1 Hz (null MICH signal for BHDC_SUM to balance?)
   - Measure optical gain also for BHDC_SUM and BH55_Q demodulated at audio dither
   - Lock LO phase at different sign so that we can sweep LO phase over ~180 deg
   - Sign-sensitive optical gain measurement (demodulation with BS motion necessary)
 - Compare with expected values from simulations
 - Why do we have 55 degrees offset? Expected offset is 90 degrees...
   - Check if there is any RAM in 55 MHz in the input beam by measuring AM with ITM single bounce

  17281   Thu Nov 17 16:48:07 2022 AnchalFrogsComputer Scripts / ProgramsFSS SLOW servo running Now

I've moved the FSS Slow PID script running to megatron through systemd daemons. The script is working as expected right now. I've updated megatron motd and the always running scripts page here.

  17280   Thu Nov 17 15:53:47 2022 JCConfigurationCamerasITMX Camera -- attempt at fix

The issue was the power supply.


I found that an old BNC cable for ITMXF video existed so I first tried swapping both ends of the cable, one on the ITMX viewport and the other one in the video MUX input in the rear. This didn't fix the issue.

I searched around in the CCD cabinet by XARM and found an identical analog camera so I swapped it and got the same image ...

I then searched for a AC/DC supply cable, but couldn't find one.


  17279   Thu Nov 17 14:12:58 2022 yutaSummaryBHDOptical gain calibrations for BHD MICH with lower UGF

[Paco, Yuta]

We found that MICH UGF was unexpectedly high, ~200 Hz, in the measurement yesterday, which makes the closed loop gain to be more than one at MICH line injection at 211.1 Hz.
We did optical gain calibrations for AS55, BH55 and BHDC_DIFF in BHD MICH again with UGF at around 10 Hz.
This solved the inconsistent result with free swing calibration.

What we did:
 Did the same measurement for BHD MICH as written in 40m/17274, but with MICH UGF of ~10 Hz and LO PHASE UGF of ~15 Hz (see OLTFs in Attachment #1, and filter configurations in Attachment #2).
 Updated sensing matrix is as follows

Sensing Matrix with the following demodulation phases (counts/counts)
{'AS55': -163.52789698340882, 'BH55': 152.7860744565449}
      Sensors        	MICH @211.1 Hz       	LO1 @287.1 Hz       	AS1 @281.79 Hz       	
C1:LSC-AS55_I_ERR_DQ	1.85e-05 (-118.82 deg)	3.31e-07 (-32.19 deg)	7.86e-07 (112.27 deg)	
C1:LSC-AS55_Q_ERR_DQ	7.32e-04 (59.57 deg)	1.19e-06 (158.17 deg)	9.07e-07 (-92.25 deg)	
C1:LSC-BH55_I_ERR_DQ	5.02e-04 (-123.21 deg)	1.79e-05 (-26.73 deg)	1.76e-05 (-120.23 deg)	
C1:LSC-BH55_Q_ERR_DQ	1.75e-03 (59.57 deg)	2.71e-04 (-22.64 deg)	2.56e-04 (-114.37 deg)	
C1:HPC-BHDC_DIFF_OUT	1.00e-03 (-115.93 deg)	3.09e-05 (-14.99 deg)	2.84e-05 (-110.23 deg)	

 Using BS actuation efficiency of 26.08e-9 /f^2 m/counts (40m/16929), optical gain for AS55_Q and BHDC_DIFF for MICH is

7.32e-03 / (26.08e-9/(211.1**2)) = 1.25e9 counts/m (AS55_Q for MICH) This is consistent with freeswing measurement (1.24e9 m/counts) 40m/17274
1.00e-03 / (26.08e-9/(211.1**2)) = 1.71e9 counts/m (BHDC_DIFF for MICH)

 Using LO1 and AS1 actuation efficiencies of 3.14e-8 /f^2 m/counts (40m/17206), optical gains for BH55_Q for LO1 and AS1 are

2.71e-04 / (3.14e-8/(287.1**2)) = 7.12e8 counts/m (BH55_Q for LO1)
2.56e-04 / (3.14e-8/(281.79**2)) = 6.47e8 counts/m (BH55_Q for AS1)

  (Notebook: /opt/rtcds/caltech/c1/Git/40m/scripts/CAL/SensingMatrix/MeasureSensMatBHD.ipynb)

 - Compare them with expected values
 - Measure them with different locking points (different LO phases, MICH offsets; LO phase can be calibrated using optical gain calibration of BH55_Q)

  17278   Thu Nov 17 12:24:48 2022 PacoConfigurationCamerasITMX Camera -- attempt at fix

I found that an old BNC cable for ITMXF video existed so I first tried swapping both ends of the cable, one on the ITMX viewport and the other one in the video MUX input in the rear. This didn't fix the issue.

I searched around in the CCD cabinet by XARM and found an identical analog camera so I swapped it and got the same image ...

I then searched for a AC/DC supply cable, but couldn't find one.


Coming in this morning, I found ITMX Camera malfunctioning.


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