PSL Status: SysStat: All Green, except VB program offline Output power: 33.0w Frontend Watch: Green HPO Watch: Red PMC: Locked: 5 days, 14 hours, 35 minutes Reflected power: 2.3w Power Transmitted: 23.3w Total Power: 25.6w FSS: Locked: 2 days, 15 hours, 58 minutes Trans PD: 1.944v ISS: Diffracted power: 7.44% Last saturation event: 2 days, 19 hours, 11 minutes
Will run a couple DC tests to insure clearance.
broken by people starting to go into the LVEA. Start: 2014/12/22/01:05 Stop: 2014/12/22/17:25 Duration:16h20min We do see O(1%) power drifts, including a step arounbd 8:30am local - presumably due to human activity. We will chase down where this comes from.
Kiwamu pointed out that PSL or IMC fluctuations could be the culprit in the ~1% drop in power build up over the course of 14 hours. I attached some trends that show that the PSL output is the cause of the long term degredation and the jump at ~16:01 UTC.
I also attached the WFS loops that we've closed in the past few days (BS,PR3, PRM, SR3, SRM) to see how they are reacting to the change in power and they seem to not vary much over the course of the night. I've also attached some trends of the WFS/optics that we're not using (RF45 and PR2) to see if the uncontrollled DOFs are also coupled into this power loss, it looks like there might be some of this occuring when comparing thhe WIT sensors on PR2 to the power buildup.
Seismic : Working on ITM configurations Need to take Safe.Snap of BSC1, BSC2, BSC3 Calibration of HEPI system pressures Suspensions: Clean up after ETM optics work
no restarts reported for both days. Conlog frequently changing channels reports attached.
Evan, Stefan With the winds calming down again, we did some more SR3 alignment work: - We noticed that for SCR1_Y AS B 36 I is still the best signal. It has - less "phase lag", presumably due to a reduced coupling to the BS. This allows us to do a high bandwith loop. - a small enough offset that servoing it to zero makes sense for reducing build-up fluctuations. - Thus we closed the yaw loop with a UGF of 3.3Hz. Engaging it is in the Guardian. - We tried to play the same game for the pitch loop, with less sucess. - all signals have some RF offset. - none of the signals seem to have low enough "phase lag" for a high BW loop. We should make sure this phase lag is not due to some broken whitening filter. - Thus for now we left pitch in the configuration described in alog 15769. Evan is now also updating the WFS relieve. We will leave DRMI locked for the night.
The DRMI guardian has a new version of the OFFLOAD_DRMI_ASC state. This uses the script offloadOpticAlign.py, which slowly bleeds off the M1 lock outputs of PRM, PR3, BS, SR2, SR3, SRM, and IM4 to their respective alignment sliders.
I went into the PSL to check out possibilities for redoing the top periscope piezo mirror mount, which I think is responsible for the 250 Hz peak in DARM at LLO (Link). The secondary purpose was to check the recovery time for a 10 minute incursion. The IMC did not loose lock but suffered intensity spikes beginning when I went in, and quickly dissapating so that they were gone by an hour after I left. The plots show MC2 TRANS and ISS_AOM_DRIVER_MON in an overview and a zoom into one of the intensity spikes. The zoom suggests ISS oscillations. The step in MC2 TRANS was when Evan, seeing the spikes, shut down the gaurdian.
Robert, Evan
Elli, Thomas, Stefan
- We found that the DRMI build-up fluctuations reported in alog 15765 were mostly due to a small offset in the WFS locking point for the SRC (feed back to SRM yesterday, switched to SR3 today).
- We fine-tweaked the input matrix mixing signals from AS36 A (orthogonal to the BS signal) and AS36 B (I&Q), such that we maximize the SR3 signal and get a good locking-point offset.
The matrix is:
AS A RF36I -0.45
AS A RF36Q 0.89
AS B RF36I 1.1
AS B RF36Q -0.77
This was found for pitch. Yaw was confirmed to be close, but wind prevented further fine-tuning. Using this significantly reduced the build-up fluctuations.
- Next we commissioned the a high BW loop for SR3. The filters are
PIT: zpk([0.06+i*0.815;0.06-i*0.815;0.3+i*3.25;0.3-i*3.25],[0.3+i*2.87;0.3-i*2.87;11.1111+i*38.4258;11.1111-i*38.4258],1,"n")
YAW: zpk([0.13+i*1.24;0.13-i*1.24;0.15+i*2.88;0.15-i*2.88],[0.15+i*2.48;0.15-i*2.48;11.1111+i*38.4258;11.1111-i*38.4258],1,"n")
They were successfully tested up to a UGF of 6Hz using an optical lever. However, on the WFS we could not go that high because there was significant cross-talk from the other loops.
Thomas will attach a measured transfer function.
- We left the feed-back on SR3 (the guardian sets this up), but with maybe 10 times lower BW.
- We also noticed that the high BW WFS cause more violent lock losses. We thus put (generous) limiters to all the top stages.
Unfortunately the winds are at 60mph again, so we won't leave it locked tonight.
Pit and Yaw TFs for high bandwidth filters mentioned above.
I have reconfigured conlog to remove the constantly noisy H1:ALS-Y_VCO_TUNEOFS and the 2 disconnected channels. Details are:
+ H1:ALS-X_WFS_AUTOC_SWITCH
+ H1:ALS-Y_WFS_AUTOC_SWITCH
- H1:ALS-X_WFS_AUTOC_SWTCH
- H1:ALS-Y_VCO_TUNEOFS
- H1:ALS-Y_WFS_AUTOC_SWTCH
inserted 2 pv names
deleted 3 pv names
model restarts logged for Fri 19/Dec/2014
2014_12_19 11:28 h1fw1
2014_12_19 14:48 h1hpiham3
2014_12_19 14:49 h1isiham3
h1fw1 unexpected restart, SEI HAM3 restarted to see if it would fix a problem. Conlog frequently changing channels report attached.
Stefan, Kiwamu,
We did some more ASC optimizations tonight in DRMI. We are leaving the DRMI locked overnight to see what drfits on a time scale of hours.
Here is a list of what we did:
All the modifications and new loops are coded in not only in the ISC_DRMI guardian but also ISC_DOF guardian so that they do not mess up the initial alignment WFSing.
Here are two plots of POP18 & POP90, and POP90 & AS90. The RIN fluctuations are: POP18: 2.2% peak-to-peak POP90: 8% peak-to-peak AS90: 0.8% peak-to-peak
Lock lost at 1103105129 ~ 2014-12-20-10-04 UTC
Attached are some trends leading up to the loss of lock, it lasted for about 2 hours.
It looks like something could have rung up the input to th WFS servo loops and this caused some instability, I've attached some trends that show the in/outs of the ASC WFs at tthe time of unloking but it's hard to tell who's the culprit exactly.
Last night I tried a new loop topology for the OMC alignment servos, using the inputs to the OMC SUS that were added to the model a few weeks ago.
The idea here is to diagonalize the DC alignment in HAM6, using OM1 and OM2 for the centering on the AS WFS, and use OM3 and the OMC SUS for the centering into the OMC.
I measured the sensing matrix for OM3,OMCS {P,Y} --> OMC-ASC ANG,POS {X,Y}, took the inverse, and used this for the output matrix (DOF2TT). This kind of worked; I was able to close all four loops and engage the AS WFS DC centering in parallel. But the centering on the OMC wasn't very stable, and turning on the integrators caused an instability in the yaw loops. I think the problem is that we're using loops designed for the tip-tilts to actuate on a 2-stage suspension; a better approach is to invert the OMC SUS --> OMC QPD transfer function and put this into the OMCSUS ASC filter banks. But, my earlier fear that the OMCSUS actuation was too weak doesn't appear to be true. This scheme should work once we account for the complications in the OMC SUS transfer function.
A screenshot of the output matrix from ANG,POS --> OM3, OMCS is attached. You can see that the OMCS is 1000x weaker than the tip-tilt. For now I have reverted to the old configuration, which uses OM1 and OM2.
After I reverted back I noticed that the dither loops had developed an instability! They were stable as recently as 10 days ago, according to conlog nothing had changed. We'll need to investigate the dither alignment chain in the new year.
[Mackenzie, Eleanor, Paul]
This afternoon we got the PLL aux laser measurement up and running, and fortunately this happened to coincide with a locked DRMI.
We were initially able to observe the FSR dips, as we had seen them previously. We decided since we had the benefit of a locked DRMI we would try adding the clipping objects in the aux laser input path, and also in front of the REFL AIR B diode that was used to detect the beat note between the aux laser reflected from the PRM and the PSL beam reflected from the PRM.
We observed new features in the transfer function, which are likely candidates for higher-order mode resonances. Attached are two preliminary plots of sweeps close to two FSR HG00 resonances.
A very quick calculation of the PRC one-way Gouy phase from these data is as follows:
HG00 peak resonance frequency - HG10 peak resonance frequency = 0.3MHz.
Fraction of FSR = 0.3/2.6 = 0.1154.
Convert to degrees one way Gouy phase: 0.1154*180 = 20.77degrees.
With the ITMs that are currently installed, we expect a one-way Gouy phase in the PRC of about 18 degrees (with no ITM thermal lensing). Design value accounting for thermal lens in ITMs from 18W input power and 0.5ppm absorption on the ITM HR surface is 25 degrees.
Worth noting is that the DRMI was locked during this measurement, not the PRMI. It's not clear to me yet how this affects the results – maybe not much. Also, evidence for the additional peaks really being due to HOMs is the repeated resonance a further 3MHz away from the HG00 resonance, which I expect is the HG11+HG20+HG02 mode resonance. More precise analysis and measurements to follow.
Thomas, Stefan, Jeff, Kiwamu, Elli
Continuing along the same line as yesterday's work on PR3 (alog 15727), we have designed high-bandwidth (<10Hz) actuation filters for the PRM. These filters are applied to H1ASC-PRC1P and H1ASC-PRC1Y in the central part of the ASC WFS servo.
The filters added to ASC WFS central are called 'PRM^-1' and are:
H1:ASC-PRC1_P: zpk([0.2+i+0.9;0.2-i*0.9;0.05+i*3.41;0.05-i*3.41],
[0;0.2+i*2.75;0.2-i*2.75;0.125+i*9.99922;0.125-i*9.99922],1,"n")
H1:ASC-PRC1_Y: zpk([0.04+i*1.08;0.04-i*1.08;0.1+i*2.08;0.1-i*2.08;0.05+i*3.43;0.05-i*3.43],
[0;0.15+i*1.8;0.15-i*1.8;0.05+i*3.3;0.05-i*3.3],1,"n")
Some old unused filters were also removed.
Low-pass filters called 'RLP17' were added to the PRM M3 locking filters in pitch and yaw:
H1:SUS-PRM_M3_LOCK_P: zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")
H1:SUS-PRM_M3_LOCK_y: zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")
I had to sighly correct the filters to make them stable. Attached is what we now have running. The filters are: PITCH: zpk( [0.1+i*1.02;0.1-i*1.02;0.12+i*3.35;0.12-i*3.35], [0.12+i*2.75;0.12-i*2.75;11.1111+i*38.4258;11.1111-i*38.4258] ,1,"n") YAW: zpk( [0.015+i*1.09;0.015-i*1.09;0.03+i*2.05;0.03-i*2.05;0.02+i*3.43;0.02-i*3.43], [0.05+i*1.75;0.05-i*1.75;0.02+i*3.25;0.02-i*3.25;11.1111+i*38.4258;11.1111-i*38.4258],1,"n")
Note, commissioners (Kiwamu/Evan) report that they turned these filters off ~April 21st, 2015 since they were no longer needed. Filters now off are PRM M3 LOCK P and Y FM9 (RLP17). SDF has been updated.
Jim, Hugh, Krishna, Jeff, Fabrice:
We keep investigating the sensor corrction issue on HAM3. What we found yesterday is that it depends on which blends are engaged. We can't explain why yet. We did additional tests today:
- we turned off all CPSs of all HAM-ISI and BSC-ISI in the corner station. No change.
- we checked the jumpers of all HAM3 CPS boards. All good.
- we tried to apply large offset in case it would reduce some kind of cable touching/rubbing (+/-400 um in HEPI Z, and +/-400 um in ISI X,Y, Z). No change.
Finally, we tried to do the Z sensor correction to HEPI. In the plot attached:
- Red curves is HAM3 ISI isolated, no sensor correction
- Green Curve, we turn ON the sensor correction in X and Y to the HAM-ISI
- Blue Curve, we also turn on Z sensor correction to ISI. The 0.6 HZ peak shows up. For some reason it also reduces X at the microseism.
- Brown, we do the Z sensor correction to HEPI instada of ISI. The peak is still there in the CPS, but not in the GS13. It's unclear why.
The last configuration looks good from the GS13s, but it's unclear yet how good it is for the cavity. More info on that is coming.
One more thing that Fabrice forgot to mention in this recap: - they restarted the front-end processes for H1ISI and HPI HAM3 (see 15755) -- and also saw no change. Perhaps during a future maintenance day, we can hard-reboot the entire chassis. Some further speculation / questions: - That we *don't* see the feature in the GS13s when we're in low-frequency blend when we feed Z sensor correction to HPI (but we still see the feature in the CPS) rules out the GS13s as the source of the problem. - The 0.6 [Hz] feature is modifiable by changing the RX / RY blend filters -- higher blend frequency means less 0.6 [Hz] feature. RX/RY implies it's a differential vertical noise, in that one of two of the three CPS are causing the problem. - Higher blend means more CPS is being used. Wouldn't you think that if the problem is in the CPS, then using more of them would make the problem worse? - Could it be some subtle, small electronics cross-talk between the STS and the CPS that goes into oscillation? - We're grasping at straws. This stinks. @DetChar -- I know it's impossible to figure out the state of the ISIs offline, but can you track this chamber over time and see at least how long we've seen a 0.6 [Hz] feature? It might take Keith Riles type *days* worth of averaging to find it... It would be also good take Keith Riles type high-resolution ASDs to find out how sharp the feature is, and to quantify how the heck 1.12 [Hz] is related to 0.6 [Hz]...
In case detchar people are curious about the configuration of this chamber over break, when I came in this morning I found the ISI in what we thought was the good state in December. That is, X&Y sensor correction on the ISI, Z on HEPI and normal blends, isolation loops. I doubt anyone changed the configuration since the 19th of December.
Here are the current ROMs after unlocking HEPI:
1.0mm ROM H1 H2 H3 H4- V1+ V2+ V3+ V4+
0.9mm ROM V2- V4-
0.8mm ROM V1- V3-
0.7mm ROM H4+