[JC, Tega, Paco ]
I would like to mention that during the Vacuum startup, after the AUX pump was turned on, Tega and I were walking away while the pressure decreases. While we were, valves opened on their own. Nobody was near the VAC Desktop during this. I asked Koji if this may be an automatic startup, but he said the valves shouldn't open unless they are explicitely told to do so. Has anyone encountered this before?
[Paco, Tega, JC, Yehonathan]
We followed the instructions here. There were no major issues, apart from the fb1 ntp server sync taking long time after rebooting once.
We noticed that ETMY had to much RMS motion when the OpLevs were off. We played with it a bit and noticed two things: Cheby4 filter was on for SUS_POS and the limiter on ULCOIL was on at 0 limit. We turned both off.
We did some damping test and observed that the PIT and YAW motion were overdamped. We tune the gain of the filters in the following way:
These action seem to make things better.
We realized the DCPD - B beam path was already using a 95:5 beamsplitter to steer the beam, so we are repurposing the 5% pickoff for a 55 MHz RFPD. For the RFPD we are using a gold RFPD labeled "POP55 (POY55)" which was on the large optical table near the vertex. We have decided to test this in-situ because the PD test setup is currently offline.
Radhika used a Y1-1025-45S mirror to steer the B-beam path into the RFPD, but a lens should be added next in the path to focus the beam spot into the PD sensitive area. The current path is illustrated by Attachment #1.
We removed some unused OPLEV optics to make room for the RFPD box, and these were moved to the optics cabinet along Y-arm [Attachment #2].
In parallel to setting up the optical path configuration in the ITMY table, we repurposed a DB15 cable from a PD interface board in the LSC rack to the RFPD in question. Then, an SMA cable was routed from the RFPD RF output to an "UNUSED" I&Q demod board on the LSC rack. Lucky us, we also found a terminated REFL55 LO port, so we can draw our demod LO from there. There are a couple (14,15,20,21) ADC free inputs after the WF2 and WF3 whitening filter interfaces.
We followed rana's suggestion for stress relief on the SMA joint in the BH55 RFPD that Radhika resoldered. We used a single core, pigtailed wire segment after cleaning up the solder joint on J7 (RF Out) and also soldered the SMA shield to the RF cage (see Attachment #1). This had a really good effect on the rigidity of the connection, so we moved back to the ITMY table.
We measured the TEST in to RF Out transfer function using the Agilent network analyzer, just to see the qualitative features (resonant gain at around 55 MHz and second harmonic suppression at around 110 MHz) shown in Attachment #2. We used 10kOhm series resistance in test input path to calibrate the measured transimpedance in V/A. The RFPD has been installed in the ITMY table and connected to the PD interface box and IQ demod boards in the LSC rack as before.
Locked LO phase to ITMX single bounce beam at the AS port, using the DCPD (A-B) error point and actuating on LO1 POS. For this the gain was tuned from 0.6 to 4.0. A rough Michelson fringe calibration gives a counts to meters conversion of ~0.212 nm/count, and the OLTF looks qualitatively like the one in a previous measurement (~ 20 dB at 1 Hz, UGF = 30 Hz). The displacement was then converted to phase using lambda=1e-6; I'm not sure what the requirement is on the LO phase (G1802014 says 1e-4 rad/rtHz at 1 Hz, but our requirement doc says 1 to 20 nrad/rtHz (rms?)... anyways wit this rough calibration we are still off in either case.
The balancing gain is obvious at DC in the individual DCPD spectra, and the common mode rejection in the (A-B) signal is also appreciable. I'll keep working on refining this, and implementing a different control scheme.
Update; the high frequency ( > 100 Hz) drop is of course not real and comes from a 4th order LP filter in the HPC demod I filter which I haven't accounted for. Furthermore, we have gone through the calibration factors and corrected a factor of 2 in the optical gain. Then, I also added the CLTF to show in loop and out of loop error respectively. The updated plot, though not final, is in Attachment #1.
Repeated the LO phase noise measurement, this time with the LO - ITMY single bounce, and a couple of fixes Koji hinted at including:
This time, after alignment the fringe amplitude was 500 counts. Attachment #1 shows the updated plot with the calibrated noise spectra for the individual DCPD signals A and B as well as their rms values. Attachment #2 shows the error point, in loop and the estimated out of loop spectra with their rms as well. The peak at ~ 240 Hz is quite noticeable in the error point time series, and dominates the high frequency rms noise. The estimated rms out of loop noise is ~ 9.2 rad, down to 100 mHz.
We took lo phase noise spectra actuating on the for different optics-- LO1, LO2, AS1, and AS4. The servo was not changed during this time with a gain of 0.2, and we also took a noise spectrum without any light on the DCPDs. The plot is shown in Attachment #1, calibrated in rad/rtHz, and shown along with the rms values for the different suspension actuation points. The best one appears to be AS1 from this measurement, and all the optics seem to show the same 270 Hz (actually 268 Hz) resonant peak.
Koji suspected the observed noise peak belongs to some servo oscillation, perhaps of mechanical origin so we first monitored the amplitude in an exponentially averaging spectrum. The noise didn't really seem to change too much, so we decided to try adding a bandstop filter around 268 Hz. After the filter was added in FM6, we turned it on and monitored the peak height as it began to fall slowly. We measured the half-decay time to be 264 seconds, which implies an oscillation with Q = 4.53 * f0 * tau ~ 3.2e5. This may or may not be mechanical, further investigation might be needed, but if it is mechanical it might explain why the peak persisted in Attachment #1 even when we change the actuation point; anyways we saw the peak drop ~ 20 dB after more than half an hour... After a while, we noticed the 536 Hz peak, its second harmonic, was persisting, even the third harmonic was visible.
So this may be LO1 violin mode & friends -
We should try and repeat this measurement after the oscillation has stopped, maybe looking at the spectra before we close the LO_PHASE control loop, then closing it carefully with our violin output filter on, and move on to other optics to see if they also show this noise.
We started the day by taking a spectrum of C1:HPC-LO_PHASE_IN1, the BHD error point, and confirming the absence of 268 Hz peaks believed to be violin modes on LO1. We then locked the LO phase by actuating on LO2, and AS1. We couldn't get a stable loop with AS4 this morning. In all of these trials, we looked to see if the noise increased at 268 Hz or its harmonics but luckily it didn't. We then decided to add the necessary output filters to avoid exciting these violin modes. The added filters are in the C1:SUS-LO1_LSC bank, slots FM1-3 and comprise bandstop filters at first, second and third harmonics observed previously (268, 536, and 1072 Hz); bode plots for the foton transfer functions are shown in Attachment #1. We made sure we weren't adding too much phase lag near the UGF (~ 1 degree @ 30 Hz).
We repeated the LO phase noise measurement by actuating on LO1, LO2 and AS1, and observe no noise peaks related to 268 Hz this time. The calibrated spectra are in Attachment #2. Now the spectra look very similar to one another, which is nice. The rms is still better when actuating with AS1.
After the above work ended, I tried enabling FM1-3 on the C1:HPC_LO_PHASE control filters. These filters boost the gain to suppress noise at low frequencies. I carefully enabled them when actuating on LO1, and managed to suppress the noise by another factor of 20 below the UGF of ~ 30 Hz. Attachment #3 shows the screenshot of the uncalibrated noise spectra for (1) unsupressed (black, dashed), (2) suppressed with FM4-5 (blue, solid), and (3) boosted FM1-5 suppression (red).
Today we calibrated the actuation on BHD suspended optics: LO1, LO2, AS1, AS4.
Actuation transfer functions for these optics look good.
For a reference we locked LO-ITMY single bounce using the LSC MICH loop. The error point was BH55_Q, the whitening filter gain was 45 dB, IQ demod rotation angle = 151.061 deg, the servo gain was -10, and the actuation point was ITMY. The measured UGF for this loop was ~ 150 Hz when FM2, 3, 4, 5 and 8 were all enabled. Note FM8 is an elliptic low pass (600 Hz cutoff).
We then lock the LO phase by feeding back BH55_Q_ERR to the actuation points under test with exactly the same filters but a servo gain of 0.6 but otherwise we are using the same servo filters FM2, 3, 4, 5 and 8 for this controls. The measured UGFs were all near ~ 70 Hz.
Here we had to be careful not to excite mechanical (?) resonances similar to the previously observed "violin" modes in LO1. In particular, we first noticed unsupressed 816 Hz noise in AS1 was being reinjected by the loop sometimes tripping the local damping loops, so we added bandstop filters at the AS1_LSC output filter bank. The resulting loop was then allowed to increase the gain and turn on FM2 and FM3 (boosts). This was also the case in AS4, where 268 Hz and second + third harmonics appeared to be excited by our feedback control. Finally, AS4 also displayed some mechanical excitation at 96.7 Hz, which seemed too low to be a "violin" mode, and its "Q" factor was not as high. We added a bandstop for this as well.
Attachment #1 shows LO_PHASE OLTFs when actuating in the different optics. By taking the actuation ratios (Attachment #2) with respect to our ITMY actuation reference and which had previously been calibrated to be 4.74e-9 / f^2 m / cts, we now have estimated our BHD suspension actuation calibrations to be:
This magnitudes are consistent with the expected coil driver ranges (about a factor of 10 difference).
I pressed the Auto-Z(ero) button for ~ 3 seconds at ~9:55 local (pacific) time on the trillium interface on 1X5.
[Yuta, Paco, JC]
This eq potentially tripped ETMY, PR2, PR3, AS1, AS4, SR2, LO1, LO2 suspensions during today's WB meeting. We restored them into normal local damping.
We aligned the arm cavities just to verify things were ok and then moved on to BHD comissioning. No problems spotted so far.
Today we locked LO phase with BH55 + Audio dithering
We worked with MICH locked using AS55_Q with an offset = 50. Our BH55_Q_ERR is the same as in the previous elog (in this thread). We enabled audio dithering of AS1 to produce 280.54 Hz sidebands (exc gain = 15000). We used ELP80 (elliptic, 4th order lowpass with the second resonant notch at 280.54 Hz) at the BH55_Q_AS1_DEMOD_I output. This allowed us to generate an error signal to feedback into AS1 POS. Attachment #1 shows a screen capture of this configuration.
We close a loop with the above configuration to lock the LO phase using only filters FM5, FM8 and then optionally boost with FM2. The compromise we had to make because of our phase margin was to achieve UGF ~ 20 Hz (in contrast with ~ 70 Hz used in single bounce). Attachment #2 shows the measured OLTFs for LO_PHASE control using this scheme; the red was the final measured loop, while the blue was our initial reference before increasing the servo gain.
Turned HEPA ON this morning at 10:28 local (pacific time) or gpstime = 1350802758. WFS ON right after that. IMC was locked and nominally aligned at this time.
Today we again locked the LO phase with BH55 + Audio dithering under a zero-offset MICH
We worked with MICH locked using AS55_Q with an offset = 0. Our BH55_Q_ERR is the same as in the previous elog (in this thread).We reduced the MICH offset from 50 to 0 slowly and kept an eye on the BH55 error signals. We realized that at zero offset, most of the error signal was in BH55_I_ERR (why?) so we rotated it back to BH55_Q_ERR (146 deg --> 56 deg). We then looked at the audio demod angle, and optimized it to allocated the error signal in the I quadrature (-15 deg --> 40 deg).
We close a loop with the above configuration to lock the LO phase using only filters FM5, FM8 and then optionally boost with FM2. The measured UGF ~ 20 Hz similar to the configuration with an offset present; and it seems there is some residual noise at ~ 20 Hz (observed in the residual error signal time trace with ndscope).
We added a notch filter on ETMY (the actuation point of the YARM control loop) to inject our calibration line at 575.170 Hz. The excitation is injected using the DARM Oscillator, with an exc. gain of ~ 500 (this gets us a decent > 10 SNR line in the ALS Y beat). With the arm cavity locked to the PSL (~150 Hz control bandwidth), and the aux laser locked to the cavity (~10 kHz control bandwidth) the goal of this run is to calibrate our actuator strength and more importantly to budget its uncertainty. For this we have looked at the ALS beat stability using Allan statistics; we noticed the ALS beatnote frequency fluctuations start to become dominated by 1/f (or divergent noise due to systematic drifts in the YARM loop) after 10 seconds (see Attachment #1) (we have managed to see 30 seconds stability with the HEPAs off and without locking to IMC).
Our prediction is that our demodulated calibration lines will display the least residual rms noise when averaging down to around this time. This is the only reason one would use allan statistics; to quantify the separation between statistical and systematic effects in a frequency measurement. To be continued...
Plan to calibrate single arm actuation strength
The analysis is as follows:
I turned all the LSC oscillators on and used the digital demod for BEATYF (fine y als beat) to grab the data. For this I added notches onto SCY ETMY LSC filter banks FM6-10 to account for these lines at 30.92, 211.10, 313.31, 315.17 Hz (basically just reusing the osc models) and adjusted the sensing matrix to actuate on ITMY.
I aligned and locked YARM, and then I aligned and locked the YAUX. The lock seems pretty robust with an avg green transmission GTRY ~ 0.185 counts for TEM00.
Trying to see other lines appear on the BEATYF demod channels, but so far no luck. I scaled down the exc gain from 500 counts (snr ~ 20 at 575 Hz) and verified the notches are working. Since I am unsure of the issue here and WFS tests are happening at 4 today, I decided to take some beat data under different conditions -->
HEPA OFF and PSL Shutter Open
HEPA OFF and
PSL Shutter Closed
gpstime end = 1352246216
HEPA ON and
We installed a steering mirror intersecting the BHD beam path and put the AS beam on the ITMY Oplev QPD (see Attachment #1 for a photo of this temporary hack) . This is done to do coil balancing of AS1/AS4, LO1/LO2. QPD sees ~ 10000 counts when the beam is centered.
We follow this procedure -- but with different sensors for all BHD suspension coil output balancing.
We dither BUTT first, lock the LO-AS fringe (DC lock), and look at the residual LO_PHASE spectrum to minimize POS coupling. We then unlock, misalign LO beam and look at the hijacked Oplev (ITMY) while dithering POS to minimize PIT and YAW couplings.
We dither BUTT first, lock thChangeset summarye LO-AS fringe (DC lock), and look at the residual LO_PHASE spectrum to minimize POS coupling. We then unlock, misalign AS beam and look at the hijacked Oplev (ITMY) PIT/YAW residual noise while dithering POS to minimize PIT/YAW coupling.
The new coil output gains are summarized in the table below:
Finally, I reverted the hacked QPD setup to restore the ITMY OPLEV.
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;
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.
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.
[Yehonathan, Yuta, Paco]
We would like to estimate:
I swapped the 1 inch BS and lenses along the POP beam to clear the apertures and avoid clipping this beam. The results are illustrated by the attached pictures; this was done right after Yuta had optimized IFO alignment so it's hopefully a good reference from now on. Yuta also tuned the alignment of BHDC path in ITMY table, which mostly improved the alignment to DCPD A (90-ish counts improved to 100-ish counts with ITMY single bounce).
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.
[Yuta, Paco, Anchal]
(a) BHDC_DIFF sensitivity to BS dither for a set of MICH offsets.
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.
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.
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.
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.
- Saved BURT backup in /users/anchal/BURTsnaps/
- Copied existing code for mode cleaner noise budget from /users/rana/mat/mc. Will work on this from home to convert it inot new pynb way.
Get baseline IMC measurements (passive):
- What is MC_F? Let's find out.
- On MC_F Cal window titled 'C1IOO-MC_FREQ', we turned off ON/OFF and back on again.
- Using diaggui, we measured ASD of MC_F channel in units of counts/rtHz.
- Using diaggui, measured ASD from a template (under /users/Templates) and overlay the 1/f noise of the NPRO (Attachment 1)
- WFS Master
- Went through the schematic and tried to understand what is happening.
- Accidentally switched on MC WF relief (python 3). Bunch of things were displayed on a terminal for a while and then we Ctrl-C it.
- The only thing we noticed that change is a slight increase in WFS1 Yaw, and a corresponding decrease in WFS1 Pitch, WFS2 Pitch, and WFS2 Yaw.
- We need to find out what this script does.
- First ran burtgooey as last time.
- Installed pyepics on base environment of donatella
- Clicked on ON in the drop down of "! More Scripts" below "! Scripts XARM" in C1ASS.adl
- Clicked on "Freeze Outputs" in the same menu after some time.
- Noticed that the sensing and output matrix of ASS on XARM and YARM look very different. The reason probably is because the YARM outputs have 4 TT1/2 P/Y dof instead of BS P/Y on the XARM. What are these TT1/2?
(Probably, unrelated but MC Unlocked and kept on trying to lock for about 10 minutes attaining the lock eventually.)
- From scripts/XARM we ran lockXarm.py from outside any conda environment using python command.
- Weirdly, we see that YARM is locked??? But XARM is not. Maybe this script is old.
- C1:LSC-TRY-OUTPUT went to around 0.75 (units unknown) while C1:LSC-TRX-OUTPUT is fluctuating around 0 only.
POY11 Spectrum measurement when YARM is locked:
- Created our own template as we couldn't find an existing one in users/Templates.
- Template file and data in Attachment 2.
- It is interesting to see most of the noise is in I quadrature with most noise in 10 to 100 Hz.
- Given the ARM is supposed to be much calmer than MC, this noise should be mostly due to the mode cleaner noise.
- We are not sure what units C1:LSC-POY11_I_ERR_DQ have, so Y scale is shown with out units.
Trying to lock Green YEND laser to YARM:
- We opened the Green Y shutter.
- We ensured that when temperature slider og green Y is moved up, the beatnote goes up.
- ARM was POY locked from previous step.
- Ran script scripts/YARM/Lock_ALS_YARM.py from outside any conda environment using python command.
- This locked green laser but unlocked the YARM POY.
Things moving around:
- Last step must have made all the suspension controls unstable.
- We see PRM and SRM QPDs moving a lot.
- Then we did burt restore to /opt/rtcds/caltech/c1/burt/autoburt/today/08:19/*.snap to go back to the state before we started changing things today.
[Paco left for vaccine appointment]
- However the unstable state didn't change from restore. I see a lot of movement in ITMX/Y. PRM and BS also now. Movement in WFS1 and MC2T as well.
- I closed PSL shutter as well to hopefully disengage any loops that are still running unstably.
- But at this point, it seems that the optics are just oscillating and need time to come back to rest. Hopefully we din't cause too much harm today :(.
My guess on what happened:
Gautam came in and noted that the optics damping watchdogs had been tripped by a >5 magnitude earthquake somewhere off the coast of Australia. So, under guided assistance, we manually damped the optics using following:
Gautum also noticed that MC autolocker got turned OFF by me (Anchal), we turned it back on and MC engaged the lock again. All good, no harm done.
- Started zoom stream; thanks to whoever installed it!
- Spent some time trying to understand how anything we did last thursday lead to the sensing matrix change, but still cannot figure it out.
- Tracking back on our actions, at ~10:30 we ran burt Restore with the 08:19/.*snap and in lack of a better suspect, we blame it on that action for now.
# ARM locking??
- Reading (not running) the scripts/XARM/lockXarm.py script and try to understand the workflow. It is pretty confusing that the result was to lock Yarm last time.
- It looks like this script was a copy of lockYarm.py, and was never updated (there's a chance we ran it for the first time last thursday)
- *Is there a script to lock the Arms?* Or should we write one? To write one, we first attempt a manual procedure;
1. No need to change RFPD InMTRX
2. All filters inputs / outputs are enabled
3. Outputs from XARM and YARM in the Output matrix are already going to ETMX and ETMY
- Maybe we can have the ARM lock engage by changing the MC directly?
4. Change C1:SUS-MC2_POS_OFFSET from -38 to -0, and enable C1:SUS-MC2_POS_OFFSET_ON
5. Manually scan MC2_POS_OFFSET to 250 (nothing happens), then -250, then back to -38 (WFS1 PIT and YAW changed a little, but then returned to their nominal values)
- Or maybe we need to provide the right gain...
6. Disabled C1:SUS-MC2_POS_OFFSET_ON (back to nominal state)
7. Look into manually changing C1:LSC-XARM_GAIN;
From the command line using python:
>> import epics
>> ch_name = 'C1:LSC-XARM_GAIN'
>> epics.caput(ch_name, 0.155) # nominal = 0.150
- Could be unrelated, but we noted a slow spike on C1:PSL-FSS_PCDRIVE (definitely from before we changed anything)
- Still nothing is happening
8. Changed the gain to 0.175, then back to 0.150, no effect... then 0.2, 0.3 ...
- Stop and check SUS_Watchdogs (should not have changed?) and everything remains nominal
- Revert all changes symmetrically.
- Could we have missed enabling FM1?
- Briefly lost MC lock, but it came back on its own (probably unrelated)
- Wrap it up for the day. In summary; no harm done to our knowledge.
- Upon arrival, MC is locked, and we can see light in MON5 (PRM) (usually dark).
# XARM locking
- Read through "XARM POX" script (path='/cvs/cds/rtcds/caltech/c1/burt/c1configure/c1configureXarm')
- Before running the script, we noticed the PRM watchdog is down, so we manually repeat the procedure from last time, but see more swinging even though the watchdog is active.
- Run a reEnablePRMWatchdogs.py script (a copy of reEnableWatchdogs.py with optics=['PRM']), which had the same effect.
- We manually disable the watchdog to recover the state we first encountered, and wait for the beam in MON5 to come to rest.
- The question is; is it fine to lock Xarm with PRM watchdog down?
- To investigate this, we look at the effect of the offset on the unwatchdog-PRM.
- Manually change 'PRM_POS_OFFSET' to 200, and -800 (which is the value used in the script) with no effect on the PRM swinging.
- Moving on, run IFO > CONFIGURE > ! (X Arm) > RESTORE XARM (XARM POX), and ... success.
# MC-POX noise spectra
- With XARM locked, open diaggui and take spectra for C1:LSC-POX11_I_ERR_DQ, C1:LSC-POX11_Q_ERR_DQ, C1:IOO-MC_F_DQ
- Lost XARM lock while we were figuring out unit conversions...
- Assuming 2.631e-13 m/counts (6941) and using 37.79 m (arm length), 1064.1 nm wavelength, we get a calibration factor of 2.631e-13 * c / (2*L*lambda) ~ 0.9809 Hz/count
- (FAQ?, how to find/compute/measure the correct calibration factors?)
- Relock XARM, retake spectra. Attachment 1 has plots for POX11_I/Q_ERR_DQ spectrum (cts/rtHz, we couldn't find relevant calibration) and MC_F_DQ in (Hz/rtHz from referring to 15576, we couldn't get the units to show on y scale.)
# MC-POY noise spectra (attempt)
- Now, run IFO > CONFIGURE > ! (Y Arm) > RESTORE YARM (YARM POY), and XARM locks (why?)
- Could PRM watchdog being down be the cause?
- Try C1ASS > (YARM) ! More Scripts > ON, and looked at YARM PIT/YAW striptool.
- C1ASS > (YARM) ! Freeze Outputs, then OFF
- Go back to IFO > CONFIGURE > ! (Y Arm) > Align YARM (ASS ON: Unfreeze), try running this then Freeze, then OFF Zero Outputs.
- Try RESTORE YARM (POY) again, still not working.
- Try RESTORE YARM ALS, then try again after opening the shutter, but also fail to lock AUX.
- Is the PRM WD behind some evil misalignment? Will move forward with XARM bc it is happy.
# ARM locking
- Attempted the IFO > CONFIGURE > ! (X Arm) > RESTORE Xarm (XARM ALS) but green failed to lock and we lost XARM lock.
- Try to recover XARM lock... success. It's nice to have a (repeatable) checkpoint.
- Attempt YARM lock. Not successful. It just seems like the lock Triggers are not raised (misalignment?)
- From C1SUS_ETMY, try changing the bias "C1:SUS-ETMY_YAW_OFFSET" manually to reduce the OPLEV_YERROR. Changed from -47 to -57.
- Retry YARM lock script... no luck
- From C1SUS_PRM, try changing the bias "C1:SUS-PRM_PIT_OFFSET" manually to reduce OPLEV errors. Changed from 34 to 22 with no effect, then realized the coil outputs are disabled because the WD is down...
- So we do the following BIAS changes "C1:SUS-PRM_PIT_OFFSET" = 34 > 770 and "C1:SUS-PRM_YAW_OFFSET" = 134 > -6
- Enable all Coil Outputs, turn WD to Normal, turn OPLEVs ON, (this time the beam does not swing like crazy).
- Fine tune BIASes "C1:SUS-PRM_PIT_OFFSET" = 770 > 805 and "C1:SUS-PRM_YAW_OFFSET" = -6 > 65
- Saw YARM locking briefly, then unlocking, but we stopped once the OPLEV_ERRs no longer overloaded (from magnitudes > 50 to ~ 40).
- Retry YARM lock... no luck
- From C1SUS_ETMY, try changing the bias "C1:SUS-ETMY_PIT_OFFSET" from -1 to 6.
Stop for the day. Leave XARM locked, MC locked.
# Initial State
- MC is locked. The PRM monitor shows some oscillations.
- POP monitor shows light flashing once in a while.
- AS monitor shows one beam along with some other flashing beam around it.
- PRM Watchdog is tripped and shutdown. Everything else is normal except for overload on SRM OpLevs.
- Donatella got a mouse promotion
# Reenabling PRM watchdog:
- The custom reEnablePRMWatchdog.py has been deleted.
- Tried enabling the coil outputs manually and switching watchdog to Normal.
- Again saw large fluctuations like yesterday.
- Probably still the same issue of how current calculated actuations to the coils is in range -600 to -900 and gives and impulse to the optics when suddenly turned on.
- Waiting for PRM to damp down a little.
- Today we plan to change the position bias on PRM C1:SUS-PRM_POS_OFFSET instead of changing biases in pitch and yaw.
- Changing C1:SUS-PRM_POS_OFFSET from 0 to +/- 100 without enabling the coils, it seems upper and lower coils are anticorrelated with just changing the position. So going back to changing pitch.
- Changing C1:SUS-PRM_PIT_OFFSET from 0 -> 780. Switched on watchdog to normal.
- PRM damped down. OpLev errors are also within range.
- Enabled both OpLevs.
# Try locking Y-Arm
- IFO>CONFIGURE>YARM>Restore YARM (POY) using Donatella. See a bunch of python error messages in the call complaining about unable to find some python 2 files. Closed it with Ctrl-C after a stuck state.
- Tried running it on Pianosa, the script ran without error but Y-Arm didn't lock.
# Try locking X-Arm
- IFO>CONFIGURE>XARM>Restore XARM (POX) on Donatella. Again a bunch of OSError messages. Donatella is not configured properly to run scripts.
- Tried running it on Piasnosa, the script ran without error but X-Arm didn't lock.
- This might mean that both arms are misaligned or the BS/PRM is misaligned.
- Moving around C1:SUS-PRM_PIT_OFFSET and C1:SUS-PRM_YAW_OFFSET in order to see if the transmitted light is misalgined. Both arms are set to acquire lock if possible. No luck.
# Hypothesis: The Arm cavity is not aligned within itself (ITM-ETM)
- Will try to lock X-Arm with green light while tuning the ETMX. Hopefully the BS and ITM are aligned so that once we align ETMX to get a green lock, the IR will also lock from the other side.
- Running IFO>CONFIGURE>XARM>Restore XARM (ALS) on Pianosa. No lock, moving forward with tunning ETMX pitch and yaw offsets. Nothing changed. Brought back to same values.
[Rana joined, Anchal moved to Rossa from Pianosa]
# Moving on to IMC suspensions characterization:
- Closed the PSL shutter, to our suprise, the MC was still locked. We thought this would take away any light from IMC but it doesn't. Maybe the IFO Overview needs to show the schematic in a way where this doesn't happen: "No light from any laser entering the MC but it still is locked with a resonating field inside."
- Shutting IMCR shutter (hoping that would unlock the IMC), still nothing happend.
- Tried shutting PSL shutter from Rossa, nothing happened to MC lock still.
- Closed shutter IOO>Lock MC> Close PSL and this unlocked the IMC. Found out that this shutter channel is C1:PSL-PSL_ShutterRqst while the one from the sitemap>Shutter>PSL changes C1:AUX-PSL_ShutterRqst. Some clarification on these medm screens would be nice.
- Disabled the MC autolocked from IOO>Lock MC screen (C1:IOO-MC_LOCK_ENABLE).
- Checked the scripts/SUS/freeswing.py to understand how kick is delivered and optic is left to swing freely.
- Next, we are looking at the C1SUS_MC1 screen to understand what channels to read during data acquisition.
- In sensor matrix, we see INMON for each sensor which is probably raw counts data from the OSEMs. Rana mentioned that OSEM data comes out in units of microns. These are C1:SUS-MC1_ULSEN_OUTPUT (and so on for UR, LL, LR, SD).
- In prep for finishing, recovered Autolocker by first opening the PSL mechanical shutter, then re-enabling the Autolocker. The IMC lock didn't immediately recover, and we saw some fuzz on the PSL-FSS_FAST trace, so we closed the shutter again, waited a minute, then re-opened it and MC caught its lock.
A tmux session named "MCFreeSwingTest" will run on Rossa. This session is running script scripts/SUS/freeSwingMC.py (also attached) which will trigger at 5:00 am to impart 30000 counts kick to MC1, MC2, and MC3 after shutting PSL shutter and disabling the MC autolocker. It will let them freely swing for 1050 sec and will repeat 15 times to allow some averaging. In the end, it will undo all the changes it does and switches on autolocker on IMC. The script is set to restore any changes in case it fails at any point or a Ctrl-C is detected.
The triggered code went on at 5:00 am today but a last minute change I made yesterday to increase number of repititions had an error and caused the script to exit putting everything back to normal. So as we came in the morning, we found the mode cleaner locked continuously after one free swing attempt at 5:00 am. I've fixed the script and ran it for 2 hours starting at 8;10 am. Our plan is to get some data atleast to play with when we are here. If the duration is not long enough, we'll try to run this again tomorrow morning. The new script is running on same tmux session 'MCFreeSwingTest' on Rossa
10:13 the script finished and IMC recovered lock.
Thu Mar 11 10:58:27 2021
The test ran succefully with the mode cleaner optics coming back to normal in the end of it. We wrote some scripts to read data and analyze it. More will come in future posts. No other changes were made today to the systems.
- Today we spent the morning shift debugging SUS input matrix diagonalization. MC stayed locked for most of the 4 hours we were here, and we didn't really touch any controls.
After jumping through few hoops, we have one successful result in diagonalizing the input matrix for MC1, MC2 and MC3.
Since the new generated matrices were created for the measurement made last time, they are of course going to work well for it. We need to test with new independent data to see if it works in general.
After Anchal left for his test, I took the time to set up the iMAC station so that Stephen (and others) can remote desktop into it to use Omnigraffle. For this, I enabled the remote login and remote management settings under "Sharing" in "System Settings". These two should allow authenticated ssh-ing and remote-desktopping respectively. The password is the same that's currently stored in the secrets.
Quickly tested using my laptop (OS:linux, RDP client = remmina + VNC protocol) and it worked. Hopefully Stephen can get it to work too.
[Jon walked in, asked him for help]
(selected through burtgooey):
burtwb -f /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2021/Mar/19/08:19/c1iooepics.snap -l /tmp/controls_1210319_113410_0.write.log -o /tmp/controls_1210319_113410_0.nowrite.snap -v <
We found that following protocol works for changing the input matrices to new matrices:
We repeated this for MC2 as well and were able to lock. However, we could not do the same for MC3. It was getting unstable as soon as cavity was locked i.e. the WFS were making the lock unstable. However, the unstability was different in different attempts but we didn't try mroe times as we had to go.
So actually, it was the C1PSL channels that had died. We did the following to get them back:
We ran the coil balancing procedure 4 times while iterating through the output matrix optimization.
Attachment 1, pages 1 to 4 show the progression of cross coupling from current output matrix (which is theoretical ideal) to the latest iteration. We plot the sensed DOF ASD which we used to determine the cross coupling when different excitations are fed using the LOCKIN1 feeding 13Hz oscillation of 200 counts amplitude along the vector defined in output matrix. That means, when we change the output matrix, in subsequent tests, we alos change the exciation direction along with it.
Unfortunately, we don't see a very good optimizations over iterations. While we see some peaks going down in sensed PIT and sensed POS (through MC_F), we rather see an increase in cross coupling in the sensed YAW.
Paco worked on alignign the beam splitter to get light on the ETMY QPD and was successful in centering it without any other changes in the settings.
MC was unlocked and struggling to recover this morning due to misguided WFS offsets. In order to recover from this kind of issue, we
The MC is now restored and the plan is to let it run for a few hours so the offsets converge; then run the WFS relief script.
Today I worked on getting the ITMY and SRM oplevs back in working order. I aligned the SRM path back onto the QPD. I put excitations on the ITMY and SRM in pitch and yaw and observed the beam at the QPDs to check for clipping. They looked clean from clipping.
Just to find out where we are currently, I plotted the ITMY and SRM oplev spectra along with the ETMY oplev spectra. ETMY seems to be very good, so comparing with this seemed useful, so we know how much we have to improve by. The SRM power spectrum appears to be around 2 orders of magnitude higher than ETMY over pretty much the whole measurement band. The ITMY power spectrum is not so bad as the SRM above about 60Hz. Next thing to do is to check the dark noise level for the ITMY and SRM QPDs.
The title of this post should of course have been " ... - comparison with ETMY" not " ... - comparison with ITMY"