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ID Date Author Type Category Subjectup
  1304   Sat Feb 14 16:53:26 2009 robUpdateLSCLocking status

Quote:
Yoichi, Jenne, Alberto, Rob

Last night, the locking proceeded until the CARM -> MC_L hand-off.
However, the MC_F gets saturated (as expected) and the IFO loses lock soon after the hand-off.
So we need to offload MC_F.
We ran the offloadMCF script, but it did not work, i.e. just waiting for CARM mode.
Looks like an EPICS flag is not set right.


I found a '$<' in the offloadMCF script. I don't know precisely what that construct means, but I think it caused the script to wait for input when it shouldn't. It probably got in there accidentally. We need to be careful when we're opening scripts just to look at how they work that we don't accidentally change them. I like to use the command 'less' for this purpose.

With this gone, the script worked properly, although the lock didn't last long. I don't know if the next stage in the process is failing or if it's just a bit too noisy in the afternoon. I didn't get a chance to do much testing since the sus controller (susvme1) went nuts. In retrospect, this could be due to something in the script, so maybe we should try a burt restore to Friday afternoon next time someone wants to look at it.
  1305   Sun Feb 15 09:35:00 2009 YoichiUpdateLSCLocking status

Quote:

I found a '$<' in the offloadMCF script. I don't know precisely what that construct means, but I think it caused the script to wait for input when it shouldn't.


'$<' acts like 'read' in csh. I might have put it in the offloadMCF script to debug the behavior of the script.
Sorry I probably forgot to remove it from the script when I left.
  1306   Sun Feb 15 15:53:21 2009 RobUpdateLSCLocking status

Quote:

I didn't get a chance to do much testing since the sus controller (susvme1) went nuts. In retrospect, this could be due to something in the script, so maybe we should try a burt restore to Friday afternoon next time someone wants to look at it.


I tried the burt restore today, it didn't work. Also tried some switching of timing cables, and multiple reboots, to no avail. This will require some more debugging. We might try diagnosing the clock driver and fanout modules, the penteks, and we can also try rebooting the whole FE system.
  1323   Thu Feb 19 04:16:17 2009 YoichiUpdateLSCLocking status
Rob, Yoichi

We checked the CM-MC cross over just before turning off the moving zero.
There was a slight bump in the gain of the MC_L loop at (I believe) the optical spring freq. (~400Hz) just below 0 dB. The phase margin there was very thin.
Removing the moving zero will increase the bump more and make the loop unstable.
Rob suggested to increase the AO gain a bit more.

To see if the AO path is really working, I connected the OUT2 of the MC board to a spare DAQ channel (C1:PEM-OSA_APTEMP).
I confirmed that the PO_DC signal is actually coming to the AO path input of the MC board.
I also hooked up the SR785 to the A excitation channel of the common mode board, so that we can measure the loop gain of the AO path.
After these preparation, the lock acquisition process became somewhat unstable. The ifo loses lock randomly at various places in the lock acquisition steps.
So, as of 4:00 am, I have not gotten a chance to try Rob's suggestion nor the TF measurement with SR785 yet.
I will continue the work tomorrow (i.e. tonight ??).

  1336   Wed Feb 25 03:10:24 2009 YoichiUpdateLockingLocking status
Rob, Yoichi, Kakeru, Kiwamu

Tonight, CARM -> MCL hand off was not stable. The MCF signal monotonically went up to +2V after CARM and MCL gain was turned down to zero.
This was repeatable and it only goes up (not down).
After a while, we found that putting sleep (~5sec) between the zeroing of CARM gain and MCL gain prevents this problem.

Handing off of CARM error signal from TR to PODC was also not robust.
It seems that the suitable gain changes every time.

tdsavg started to exit with errors. We rebooted fb40m.
When tdsavg returns an error, the cm_step script tries to write NaN into SPOB DC offset.
To prevent this, I put the tdsavg in a while loop which runs until tdsavg returns something other than NaN.

I was able to hand off to PODC several times, but could not proceed further because the IFO lost lock soon.
  1458   Wed Apr 8 02:47:42 2009 YoichiUpdateLockingLocking status
This is a summary of activities in the last few nights, although there is not much progress.

The attachment 1 and 2 show the CARM and DARM responses around 3.8kHz at different arm power levels.
The CARM error signal was PO_DC and the DARM error signal was AS2Q.
The excitations were both applied to the ETMs (I temporarily modified the output matrix so that the unsed XARM filter bank can be used to excite CARM and DARM).
DARM and CARM show very similar behavior as the power goes up.

The third attachment shows transfer functions to various signals from CARM and DARM excitations (ETMs).
Though the plot contains many curves, look at PO_DC curves (green and black).
PO_DC is used as CARM error signal but it has a larger response to DARM than CARM (by 10dB or so).
This is not good.

Although the 3.8kHz problem still exists, tonight I was able to go up to arm power = 80 a couple of times, where we are ready to hand off from PO_DC to the RF CARM signal. The hand off failed. I'm now optimizing the hand off gain, but it is difficult because the interferometer is unstable at this power level.
Attachment 1: CARM_TFs.pdf
CARM_TFs.pdf
Attachment 2: DARM_TFs.pdf
DARM_TFs.pdf
Attachment 3: DARM-CARM-Coupling.pdf
DARM-CARM-Coupling.pdf
  1522   Sat Apr 25 03:27:34 2009 YoichiUpdateLockingLocking status
Yoichi, Peter,

We are working on the final step of the lock acquisition, RF CARM hand off.
I was able to hand off the CARM error signal to RF once, but lost lock when decreasing the CARM offset to zero (it was too rapid).
I will try to make the process more robust tomorrow.
  5512   Thu Sep 22 01:45:41 2011 KeikoUpdateLSCLocking status update

Keiko, Anamaria

Tonight we want to measure the LSC matrix for PRMI and compare the simulation posted last night (#5495).

First. we locked MICH and PRCL, and measured the OLT to see how good the locking is. The following rough swept sine plots are the OLTs for MICH and PRCL. The gain setting was -10 and 0.5 for MICH and PRCL, respectively. Integrators were off. Looking at the measured plots, MICH has about 300 Hz UGF, when the gain is -20, and PRCL has about 300 HZ UGF, too, when the gain is 0.8.

MICH-OLT.pdf

PRCL-OLT.pdf

As these lokings seemed good, so we tried the LSC matrix code written by Anamaria. However it is not working well at this point. When the script add excitations to the exc channels, they kick the optics too much and the lockings are too much disturbed...

Also, we have been trying to lock PRC with the SB resonant, it doesn't work. Looking at the simulated REFL11I (PRCL) signal (you can see it in #5495 too), the CR and SB resonances have the opposite signs... But minus gain never works for PRCL. It only excites the mirror rather than locking.

  5516   Thu Sep 22 11:50:37 2011 KojiUpdateLSCLocking status update

Both loops basically have no phase margins. i.e. unstable. How can you lock PRMI with these servos?

Quote:

The following rough swept sine plots are the OLTs for MICH and PRCL. The gain setting was -10 and 0.5 for MICH and PRCL, respectively. Integrators were off. Looking at the measured plots, MICH has about 300 Hz UGF, when the gain is -20, and PRCL has about 300 HZ UGF, too, when the gain is 0.8.

 

  5513   Thu Sep 22 04:49:14 2011 AnamariaUpdateLSCLocking status update - Some Scripts, No Louck

The scripts I wrote can be found in /users/anamaria/scripts/sensemat/

]There are two of them:

- one that sets all the switches, gains, frequencies, etc, then cycles through the various RFPDs I and Q into the LOCKIN signal, so as to see the sensing matrix.

- the second one is a matlab script that takes the crappy file tdsavg outputs and makes it into a cute mag/phase matrix.

They're quite primitive at this point, I've forgotten a lot of tcsh... may improve later. But could be useful later to someone else at least.

I don't think it's particularly the fault of the script that we can't measure the sensing matrix. We can slam on the excitation by hand, and it holds for a little while. I set a wait time for lock to adjust, and most times it just oscillates a bit for a few seconds. Also, the script turns on the excitation and it's done, the rest is just measurement, then turns it off at the end. So during the script, there's not much to deal with, except keeping the lowpass filters quiet when switching the signal to demod; but that doesn't go anywhere, so it definitely doesn't disturb the ifo. Turns out pressing the RSET clear history button needs a 2 to make it happen.

I think I might prefer to set the excitation to run, and then do the old retrieve-data-later-nds-matlab thing. I do not trust these measurements without coherence and a bit of variance study, given instabilities.

Point is... Even on carrier, the PRC lock is not stable by any means. Can barely turn on low freq boosts, every other lock. Until we fix the lock stability issue, there's not much to measure I guess.

Unfortunately, I don't know how to make that happen. Before we leave on Friday we could do a few sanity checks such as measuring the noise of the RFPDs vs ADC+whitening, which I may have said I would do; and perhaps setting up a couple OSAs, one on REFL, one on AS, to make sure we know what the sidebands are doing. Both of which Rana suggested at some point.

(There used to be a quote here from Keiko here but I got mad when it reformated my entire log to be one cluster- hence the look)

  14962   Thu Oct 10 01:12:56 2019 gautamUpdateLSCLocking studies

Summary:

  1. ALS control of arms in the CARM/DARM basis seems pretty robust - I was able to hold lock for >40mins tonight. The scripted transition from POX/POY control to ALS control is pretty deterministic now.
  2. The PRMI could be locked with the arms detuned from resonance by applying an offset to the CARM loop error point.
  3. Much daytime work remains to be done before attempting any sort of reliable locking.

Hardware issues that need addressing:

  1. Both EX and EY Trans QPDs need a look. I believe the one at EY is simply blocked (on account of the mode spectroscopy project), while the one at EX shows a weird discontinuity between the Thorlabs PD and the QPD. Could be just a gain/normalization issue I guess. See Attachment #1.
  2. While the PRMI stayed locked, I don't think I was using anywhere close to optimal settings. Need to run some sensing lines, measure transfer functions etc, to make the PRMI + arms lock more robust. The PRMI always lost lock when I brought the CARM offset to 0. Could also benefit from some finesse modeling I guess. I could not get a reliable estimate of what the PRG is tonight, because the PRMI didn't stay locked as I approached 0 CARM offset.
  3. REFL 55 whitening board needs a checkup.
Attachment 1: PRFPMIstudies.png
PRFPMIstudies.png
  1419   Tue Mar 24 03:05:25 2009 YoichiUpdateLockingLocking tonight
MC1 issue:
The MC1 seems to be drifting still. I found it was off from the SUS drift-mon reference values and restored the alignment using the SUS drift-mon before I went home for dinner.
But when I came back being happy with the Japanese victory over S-Korea at the WBC final, the MC was unhappy again.
I restored the alignment of the MC1 using the SUS drift-mon once again and centered the WFS QPDs.
I will leave the MC unlocked again tonight to see the drift. You are welcome to lock the MC in the morning as I will have corrected enough data by the time people come in.

Computer overloads:
I removed some filters from suspensions to off load susvme computers.
Nonetheless, both susvme1 and susvme2 are still over loaded during the dither alignment. The alignment results are in general ok. So this is not a too serious problem.
But still it would be nice to resolve.

3.8kHz hunting:
I made several measurements of the AO path loop gains (using the SR785) and the transfer functions from the CARM excitation (actuation to the ETMs) to the PO_DC signal as the arm powers are increased.
There is a similar structure as in the AO loop found also in the CARM->PO_DC transfer functions. This implies that the problem is likely to be in the PO_DC sensor not in the MC->VCO actuator. But the MC and the VCO could still be the
cause of the problem because they were in the control loop when the CARM->PO_DC TF were measured.
The peak frequency does not seem to depend on the arm power, but the conclusion is not definite because I was only able to measure the TFs from arm power 5 to 10 (not much difference).
I will make plots and post them later.

To Do for tomorrow:
Tonight the CARM error signal was noisier than the reference spectra (broad band white noise appeared). I should check the beam centering of the SPOB PD.
Also someone should center the oplevs of the mirrors as some of them are off.
Continue to measure the TFs at various power levels.
Try to put another (Thorlabs?) PD at the POB port to get PO_DC from it.
  15491   Fri Jul 17 00:18:13 2020 gautamUpdateGeneralLocking updat
  1. I found that an EPICS channel wasn't reset to the correct value by burtrestore after the FE bootfest yesterday.
    • This cost me the whole of last night, found it finally tonight. 
    • I'll try and modify the locking scripts to better capture such errors, but ideally, we should just use Guardian or something since it's made for this purpose already.
    • Anyways, tonight I was able to re-acquire the PRFPMI lock in a completely scripted way.
  2. Locking CARM on POX remains out of reach.
    • I think this has to do with the fact that the zero-crossing of the CARM and REFL error signals are dependent on the 3f PRCL/MICH error point offsets.
    • So even if the DC gain is right, the fact that we use POX for the digital AO path and REFL for the analog AO path is leading to some conflict I think.
    • Ran out of energy tonight, I'll try again tomorrow.

The DQ channels of the ETM coils were active tonight, so I'll make the coil driver actuation budget over the next couple of days.

  1399   Fri Mar 13 05:16:21 2009 YoichiUpdateLockingLocking update
Yoichi, Osamu,

With adjustments of the loop gains during the CARM offset reduction, the IFO reaches arm_power = 25 sort of robustly unless the 3.8kHz oscillation rings up.
At arm_power = 25, the CARM and DARM start to oscillate at around 400Hz. Probably I need more gain tweaks.
Annoying thing is that the 3.8kHz oscillation sometimes rings up suddenly and kills the lock.
This can happen anywhere above arm_power = 6 or so.
Because of a strange structure in the CARM loop gain around 3.8kHz, we cannot increase the CARM UGF beyond 1kHz.
The attached plots are the AO path open loop transfer function (attm2 is the zoom of attm1) measured at arm_power = 13.

Tomorrow, I will lock the X-arm and measure the transfer function from the AO path input to the X-arm error signal to see
if there is the same structure at 3.8kHz (X-arm error signal has the 3.8kHz peak).
Attachment 1: AOTF2.png
AOTF2.png
Attachment 2: AOTF2-zoom.png
AOTF2-zoom.png
  10814   Thu Dec 18 02:23:34 2014 ericqUpdateLSCLocking update

 [ericq, Diego]

Some locking efforts tonight; many locklosses due to PRC angular motion. Furthest progress was arm powers of 15, and I've stared at the corresponding lockloss plot, with little insight into what went wrong. (BTW, lastlock.sh seems to catch the lock loss reliably in the window)

15lockloss.png

CARM and DARM loops were measured not long before this lock loss, and had nominal UGFs (~120Hz, ~20deg PM). However, there was a reasonably clear 01 mode shape at the AS camera, which I did nothing to correct. Here's a spectrum from *just* before the lockloss, recovered via nds. Nothing stands out to me, other than a possible loss of DARM optical gain. (I believe the references are the error signal spectra taken in ALS arms held away + PRMI on 3F configuration)

15spec.pdf

The shape in the DARM OLTF that we had previously observed and hypothesized as possible DARM optical spring was not ever observed tonight. I didn't induce a DARM offset to try and look for it either, though.

Looking into some of the times when I was measuring OLTFs, the AS55 signals do show coherence with the live DARM error signal at the excitation frequencies, but little to no coherence under 30Hz, which probably means we weren't close enough to swap DARM error signals yet. This arm power regime is where the AS55 sign flip has been modeled to be...


A fair amount of time was spent in pre-locking prep, including:

  • The usual X green beat alignment tweak, to make the X ALS control not terrible
  • Both ITM oplevs were centered
  • For some reason, I had to flip the signs of the REFL165 matrix elements for the PRMI...
  • "Restore PRMI SB" has ASC automatically enabled, which results in unexpected kicks even with LSC off, which caused a few minutes head-scratching
  14983   Tue Oct 22 00:52:27 2019 gautamUpdateLSCLocking updates
  1. Transition of arms from POX/POY to CARM/DARM was much smoother today - a change was made at the EX PDH setup, see here.
  2. Reliable settings for 3f locking with arms held off resonance seem to have been found.
  3. Took sensing matrix in this condition, measured loop TFs.
  4. Reduced CARM offset - reached arm powers ~50 at which point the PRMI lost lock. Reacquisition was quick though.
    • The POP22_I level seemed to decay as I reduced the CARM offset.
    • This would suggest that somehow the PRCL lock point is getting shifted as I reduce the CARM offset.
    • Tonight, I will investigate this more.
Attachment 1: PRMI3f_ALS_Oct21sensMat.pdf
PRMI3f_ALS_Oct21sensMat.pdf
  15014   Wed Nov 6 02:08:48 2019 gautamUpdateLSCLocking updates

Summary:

There seems to be stronger-than-expected coupling between CARM and the 3f sensors. 

Details:

Full analysis tomorrow, but I collected sensing matrix measurements with lines driven in PRCL,MICH and CARM at a couple of CARM offsets. I also wanted to calibrate the CARM offset to physical units so I ran some scans of the CARM offset and collected the data so I can use the arm cavity FSR to calibrate CARM. Koji suggested using REFL165_I for PRCL and REFL165_Q for MICH control - this would allow us to see if the problem was with the 1f sideband only. While the lock could be established, we still couldn't push the arm powers above 10 without breaking the PRMI lock. While changing the CARM offset, we saw a significant shift in the DC offset level of the out-of-loop REFL33_I signal. Need to think about what this means...

  15185   Tue Feb 4 02:13:02 2020 gautamUpdateLSCLocking updates

Summary:

The CARM-->RF transition remains out of reach. No systematic diagnosis scheme comes to mind.

Details:

  • Config is PRFPMI, SRM is misaligned macroscopically.
  • PRMI can easily be locked with 3f signals while CARM is offset from resonance. Aided by DAFI, I turned on the PR violin filter in the BS output section to prevent it from ringing up, making the lock much more robust.
  • When the CARM offset is reduced
    • POP22 level dips and sometimes goes negative - i don't see this in my simple simulations. POP22 is the trigger signal for MICH/PRCL loops, so to prevent the PRMI lockloss, I mix in some POPDC into the trigger matrix element.
    • Once the circulating power exceeds ~10, the ALS noise apparently increases.
    • The arms "buzz" through resonance, but the power fluctuation is nearly 0-200 in TRX/TRY, corresponding to several CARM linewidths, but all the out-of-loop ALS noise measurements have me believe that we are close to the CARM linewidth in noise. So we should only see ~factor of 2 fluctuation in power.
    • The RF error signal for CARM (=REFL 11) doesn't show any features that i can use to aid the transition / diagnose what is going on systematically.
  • Koji suggested changing the actuation for CARM from MC2 to the ETMs, and check if the MC OSEMs witness the excess motion at small CARM offsets
    • The ALS transition is scripted, so I had to make a modified version that accommodates this changed actuation scheme.
    • The usual CARM-->MC2 matrix element is -1. 
    • The frequency actuation strength of MC2 is ~3x that of the ETMs. Additionally, ETMX has 5x the series resistance of ETMY. So I used the output matrix elements shown in Attachment #1 so as to get the same loop UGF with the same loop gains elsewhere in the chain. Confirmed the actuation strength is the same using the sensing matrix infrastructure and comparing line heights.
    • Attachment #2 shows the measured UGF - both CARM and DARM look okay to me.
  • With this new ALS output matrix actuation scheme, I was able to make it to PRMI + arms on zero offset a couple of times tonight, but the drifting input alignment makes the PRMI lock not so robust anymore.

TBC. Mercifully at least the shaker stayed still tonight.

Attachment 1: modifiedOutMat.png
modifiedOutMat.png
Attachment 2: OLTFs.pdf
OLTFs.pdf
  15192   Thu Feb 6 01:25:50 2020 gautamUpdateLSCLocking updates

Summary:

I managed to partially stabilize the arm citculating powers - they stay in a region in which the REFL 11 signal is hopefully approximately linear and so I can now measure some loop TFs and tweak the transition appropriately. 

Procedure:

The main change I made tonight was to look at the REFL11 signal as I swept the ALS CARM offset through 0. I found that the maximum arm powers coincided with a non-zero REFL11 signal value (i.e. a small CARM offset was required at the input to the CARM_B filter bank). Not so long ago, I had measured the PM/AM ratio for 11 MHz to be ~10^5 - so it's not entirely clear to me where this offset is coming from. Then, I was able to turn on the integrator (z:p = 20:0) in the CARM_B filter bank while maintaining high POP_DC. At this point, I ramped up the IN2 gain on the IMC servo board (= AO path), and was able to further stabilize the power. 

Attachment #shows this sequence from earlier in the evening. Note that in this state, both ALS and IR control of CARM is in effect. The circulating power is fluctuating wildly - partly this is probably the noisy ALS control path, but there is also the issue of the (lack of) angular control - although looking at the transmon QPDs and the POP QPD signals, they seem pretty stable.

The next step will be to try and turn off the ALS control path. Eventually, I hope to transition DARM control to AS55 as well. But at this point, I can at least begin to make sense of some of the time series signals, and get some insight into how to improve the lock.

Quote:

No systematic diagnosis scheme comes to mind.

Attachment 1: semiStableArms.png
semiStableArms.png
Attachment 2: armAngStability.png
armAngStability.png
  15278   Tue Mar 17 01:22:03 2020 gautamUpdateLSCLocking updates

Summary:

No real progress tonight - I made it a bunch of times to the point where CARM was RF only, but I never got to run a measurement to determine what the DARM_B loop gain should be to make the control fully RF.

Details:

  • Touched up PMC alignment.
  • There were very few BNC cables available at the rack near SW corner of the PSL table - the short BNC cables are NOT meant to be daisy chained to make long cables to run along the arm, I removed all those.
  • Restored SR785 at LSC rack for CARM TF measurements.
  • I was able to get the CARM UGF ~5 kHz, but everytime I was trying to run a DTT swept sine to measure the ratio of DARM_B_IN1 / DARM_A_IN1, the lock was lost - not sure if this is because of the excitation injected or something else.
  • I'll probably give this another shot Wednesday eve.
  373   Thu Mar 13 02:52:06 2008 LisaConfigurationLSCLocking with 3f
Today we have tried to use the reflected signal demodulated at 3*f1 ~ 99 MHz (REFL31) for length control.
This signal is cool because it is generated by the beating of sidebands, so it is not very sensitive to what the carrier does inside the IFO.
In particular, its gain and the demodulation phase shouldn't change much while changing the CARM offset during the locking sequence.
The idea is therefore to use REFL31_I and REFL31_Q for controlling MICH and PRCL, with the goal of making the lock acquisition sequence more robust.

We minimized hardware changes by using the 199MHz demodulation board, changing the local oscillator to 99.586317 MHz, with an amplitude of +10 dbm (the 3f signals are therefore acquired as LSC-PD6_I and LSC-PD6-Q).

We locked both the PRM and the DRM in a stable way using the REFL31_I and REFL31_Q, after tuning the demodulation phase (50) and removing their offsets.
On the other hand, we weren't able to acquire the lock in the DRM configuration directly by using the 3f signals. We needed instead to use the f signals first, and switch to the 3f signals once the lock was already acquired, otherwise ending up locking DRM at a different working point.
One explanation for that might be the fact that the beam impinging upon the 3f diode is too big compared with the diode size (only 1 mm, half of the size of the f1 diode).
For these reason, in presence of misalignments, some of the reflected light goes in high order modes, which can be partially (or all) off the diode, thereby generating multi-zero crossing in the demodulated error signal.

The next step before making the test with the whole IFO is therefore to modify the telescope in front of the 3f diode in order to reduce the beam size and repeat the tests we did tonight in DRM configuration.


P.S.: We made a test by changing the frequency of the local oscillator by a little bit and then coming back to the original value. We observed that the phase of the signal can change, so every time this frequency is moved the 3f demod phase need to be retuned.

John, Rob, Rana, Lisa
  8508   Mon Apr 29 22:13:41 2013 KojiUpdateLSCLocking with ASDC

Today the locking was not as easy as that was last Friday.
So I tried something new. Today Rana talked about the ASDC locking with POPDC normalization.
This technique was tried. (This is somewhat similar to DC readout.)

PRCL
Signal source: REFL33I / Normalization POP110I x 0.04 / Trigger POP110I 20up 3down, otherwise  untouched from Friday locking
Servo: input matrix 1.00 -> PRCL Servo FM3/4/5/6 Always ON G=+0.06
Actuator: output matrix 1.00 -> PRM

MICH
Signal source: ASDC Offset -109.5 (nominal of the day -49.5) / Normalization POPDC x 1.00 / Trigger POP110I 20up 3down
Servo: input matrix 1.00 -> MICH Servo FM5 Always On G=+10000
ActuaroL output matrix -1.00 -> ITMX / +1.00 -> ITMY

Observation

- POP110I was ~120 during the lock (cf 170 on Friday). So there is some small leakage from the dark port.

- Lock was easier when FM4 of the MICH loop was turned off.

- During the lock horizontal motion of the intracavity mode was visible as usual.

Screenshot.png

  15476   Tue Jul 14 00:06:09 2020 gautamUpdateLSCLocking with POX for CARM

I tried using the POX_I error signal for the DC CARM_B path today a couple of times. Got to a point where the AO path could be engaged and the arm powers stabilized somewhat, but I couldn't turn the CARM_A path off without blowing the lock. Now the IMC has entered a temperemental state, so I'm abandoning efforts for tonight, but things to try tomorrow are:

  1. Check that the demod phase is set correctly
  2. With the CARM_B path engaged, measure some CARM OLTFs. Tonight, I was a bit over-optimistic I think, by expecting the scripted transition to take me all the way, but I think I'll have to fiddle around with the gains a bit.
  3. Check for offsets. The AO path should be AC coupled, but maybe the POX signal has some offset?

I have some data from a couple of days ago when the PRFPMI was locked as usual (CARM_B on REFL for both DC and AO paths), and the sensing lines were on, so I can measure the relative strength of the sensing lines in POX/REFL and get an estimate of what the correct digital gain should be.

The motivation here is to see if the sensing matrix looks any different with a modified locking scheme.

  15477   Tue Jul 14 01:55:03 2020 KojiUpdateLSCLocking with POX for CARM

The usual technique is that keeping the IFO locked with the old set of the signals and the relative gain/TF between the conventional and new signals are measured in-lock so that you can calibrate the new gain/demod-phase setting.

  15481   Tue Jul 14 17:28:29 2020 gautamUpdateLSCLocking with POX for CARM

From Attachment #1, looks like the phasing and gain for CARM on POX11 is nearly the same as CARM of REFL11, which is probably why I was able to execute a partial transition last night. The response in POY11 is ~10 times greater than POX11, as expected - though the two photodiodes have similar RF transimpedance, there is a ZFL-500-HLN at the POY11 output. The actual numerical values are 2.5e10 cts/m for CARM-->REFL11_I, 2.6e10 cts/m for CARM-->POX11_I, and 3.2e11 cts/m for CARM-->POY11_I.

So I think I'll just have to fiddle around with the transition settings a little more tonight. 

One possible concern is that the POX and POY signals are digitized without preamplificatio, maybe this explains the larger uncertainty ellipse for the POX and POY photodiodes relative to the REFL11 photodiode? Maybe the high frequency noise is worse and is injecting junk in the AO path? I think it's valid to directly compare the POX and REFL spectra in Attachment #2, without correcting for any loops, because this signal is digitized from the LSC demodulator board output (not the preamplified one, which is what goes to the CM board, and hence, is suppressed by the CARM loop). Hard to be sure though, because while the heads are supposed to have similar transimpedance, and the POX photodiode has +12dB more whitening gain than REFL11, and I don't know what the relative light levels on these photodiodes are in lock.

Quote:

I have some data from a couple of days ago when the PRFPMI was locked as usual (CARM_B on REFL for both DC and AO paths), and the sensing lines were on, so I can measure the relative strength of the sensing lines in POX/REFL and get an estimate of what the correct digital gain should be

Attachment 1: PRFPMI_2020712sensMat.pdf
PRFPMI_2020712sensMat.pdf
Attachment 2: LSCerrSigs.pdf
LSCerrSigs.pdf
  1509   Thu Apr 23 16:27:24 2009 YoichiUpdateLockingLocking with the cryo-pump
The last night, the IFO was unstabler than usual and the locking script often failed before reaching the power up stage.
The failure happened at random points.
I'm not sure if this is related to the operation of the cryo-pump.
The mode cleaner reflection image seemed to move around more than usual. Maybe it was just a high seismic night.
  9846   Thu Apr 24 02:12:05 2014 JenneUpdateLSCLocking without TRY

I tried some locking anyway tonight, even though we don't have TRY. 

The biggest conclusion is that I miss the auto-resonance-finding.  I've been roughly scanning the Y-ALS offset to find the POY zero crossing when I see the resonance on the test mass face cameras. 

The next-biggest conclusion, is that I can hold the PRFPMI close to resonance, using ALS for CARM and DARM.  I was trying to transition DARM to AS55, but I couldn't get the last bit of the way.  That is, I couldn't turn off the ALS control.  So, I think that AS55 wasn't actually holding DARM, until maybe the last moment or so.

Anyhow, here are some time series.  My average TRX value is around 40 counts, and POPDC is maybe 250 counts (just PRMI, POPDC is about 75 counts).  Obviously this is noisy as hell, but I'm not using any IR signals for the arms.  Near the end of this first time series, I am trying to switch to AS55 for DARM.

TRX_avg_40cts_POPDC_avg_200cts.png

Zooming in, my real lockloss is due to PRCL oscillating at ~350 Hz:

Lockloss_PRCL_350Hz.png

However, I also saw ~25Hz peaks in CARM and DARM on the spectra starting to show up, and I see a ~25 Hz oscillation in DARM a few moments after the PRCL lockloss.  (Plot #2 is a zoom of the ~1.1 second mark on Plot #3.)

Lockloss_DARM_20Hz.png


The locking parameters:

CARM:

Input:  Using the new CESAR matrix, -1*ALSX, +1*ALSY.  Beatnotes both move up in freq if temp sliders move up.

Servo: gain = 6, FMs 1, 2, 3, 5, 6, 7, 9 on.  Offset = 0 counts. 

Output = -1*MC2

DARM:

Input:  +1*ALSX, +1*ALSY

Servo:  gain = 4.  FMs 1, 2, 3, 5, 6, 7, 9 on.  Offset = 0 counts.

Output = -1*ETMX, +1*ETMY

PRCL:

Input:  +1*REFL33_I, Norm = +0.01*POPDC, sqrt engaged.

Servo:  acquisition easier with -0.04 or -0.06, less gain peaking at -0.02   FMs 4, 5 on; 2, 3, 6, 9 triggered with 0.5 sec delay.  Servo trigger = POPDC, up 100, down 10.  FM trigger = POPDC, up 300, down 20.

Output = +1*PRM

PRCL ASC off, PRM oplev on.

MICH:

Input:  +1*REFL33_Q, Norm = +0.01*POPDC, sqrt engaged.

Servo:  gain = 2, FMs 4, 5 on; 2, 3 triggered with 0.2 sec delay.  Servo trigger = POPDC, up 100, down 10.  FM trigger = POPDC, up 300, down 20.

Output = +0.5*BS, -0.2625*PRM

PDs:

REFL33 analog gain set to 30 dB for both I&Q.

AS55 set to 0 dB for both I&Q.  AS55 had DC normalization of 80 counts (which was the measured number for PRFPMI when TRX was about 0.1 count this evening)

 

  9847   Thu Apr 24 11:19:50 2014 KojiUpdateLSCLocking without TRY

This seems the ever best stability at the zero offset PRFPMI.

Can you look at REFLDC in this data stream too? How was it promising?

  9848   Thu Apr 24 14:00:42 2014 JenneUpdateLSCLocking without TRY

Here is 1 second of data, with REFLDC, POPDC and TRX:

REFLDC_1sec.png

Here is a zoom of the first 3 big peaks in TRX.  The weird jumps at the beginning of each TRX peak are due to the triggered switching between the Thorlabs trans PD and the QPD trans PD.  Clearly we need to work on their relative normalizations.  There are also little jumps after each peak as the triggering sends the signal back to the Thorlabs PD.

REFLDC_3peaks.png

Here is a zoom of the single big peak about halfway through the 1 second of data:

REFLDC_1peak.png

And here is a zoom of the tail of that peak.  It looks to me like we want to start thinking about using REFL DC when our transmitted powers are around 2 counts.  We could do as soon as 1 count, but 2 is a little farther into the dip.

REFLDC_1peak_zoom.png

  11099   Thu Mar 5 04:29:13 2015 ericqUpdateLSCLocking work tonight

Brief elog of my activities tonight:

I was able to transition the digitial CARM control to REFL11 through the common mode board a total of one time, lock broke after a few seconds.

My suspicion was that when we did this on Monday, we unintentionally had a reasonable DARM offset, which reduced the finesse enough to let us take linear transfer functions and hop over. So, tonight, I intentionally looked at transitioning to CM_SLOW at some DARM offset. Using DARM offset of a few times 0.1 really calms the "buzzing" down, and makes it fairly straightforward to measure linear CARM sensing TFs. However, the CARM optical plant seems to change a fair amount depending on the DARM offset, in such a way that I was not able to compensate well enough to repeatedly transition.


Before I did anything else tonight, I measured the ALS noise down to 0.1 Hz, as a benchmark of how things are behaving.

With the arms locked on POX/POY, the HZ calibrated ALS channels reported

  • ALSX : 471Hz RMS
  • ALSY: 298 Hz RMS

Then, with the arms CARM/DARM locked on ALS, the PDH signals reported (using a line and the HZ channels for conversion)

  • Xarm : 552 Hz RMS
  • Yarm : 264 Hz RMS

Not bad! I roughly estimate this to mean ~90pm RMS CARM/DARM motion. (If X was as good as Y, it would be ~50pm...)


Some things I feel are worth noting:

  • In an effort to avoid the ETMX issues that Jenne had last night. I used MC2 to actuate CARM, and 2xETMY to actuate DARM. None of my locklosses appeared to be due to saturation of DARM, so I think it worked fine. The main drawback seems to be that if you have a violent lock loss, you may have to wait a bit for the IMC to relock; this only happened once tonight.
  • After the IR resonance finding scripts, I would run a z servo to try and get the PDH signal to cross zero. This made the ALS CARM and DARM zeros closer to the real resonating zeros than I usually see.
  • It is lately possible to sit at higher powers (albeit with very high RIN) for sizable amounts of time. In my last lock, I was in the range of 10-60x single arm power for around 30 minutes before I blew it with a failed transition attempt.
  • The set points for the QPD servos don't change much from lock to lock. I didn't have any problem using them tonight.

Tomorrow, I'll post some transfer functions of the difference between the ALS and CARM plants that I measured.

  1382   Tue Mar 10 04:55:41 2009 YoichiUpdateLockingLocking: 3.7kHz large oscillation
Yoichi, Jenne, Alberto,

As I reported on the last Thursday, there is a large oscillation in CARM and DARM error signals (attm1).
I put notch filters (3.75kHz, Q=10, 30dB) in the CARM and DARM loops. This let us go up to the arm power of more than 20 and stay there for a while.
The dashed curves in the attm1 are the spectra when the notches are off, and the solid curves are when the notches are used.
We could somewhat suppress the DARM peaks but not CARM.
Of course this is clearly not a good solution. We should find the cause of the oscillation and kill it.

Attm2 is the spectrum of the PO_DC signal flowing in the CM board measured by the SR785. More specifically, CH1 is TP1A and CH2 is TP2A of the CM board.
This was taken right after the AO path was engaged. At this stage, the AO path gain is very low. But you can already see a seed of the oscillation in the spectrum.

Attm3 shows the same spectra taken after the arm power is increased to 4 but before the PO_DC hand off. You can see large peaks around 3.75kHz.
After this, the peaks grow as the power goes up.

Attm4 is the loop gain of the AO path after the PO_DC hand off (arm power = 4).
Attm5 is the zoom of the same TF around 3.7kHz. Clearly there is something wrong at this frequency. We should check the CM board and the MC board as well as the SPOB PD.

One time I was able to go up to arm power = 27 or so. At this power level, the DARM loop started to oscillate, probably, around the UGF.
However because of the 3.7kHz problem, we can't stay at this power level long enough to make diagnostic measurements (like open loop TF).
We should tackle the 3.7kHz issue first.
Attachment 1: CARM_DARM_Spectra.pdf
CARM_DARM_Spectra.pdf
Attachment 2: PODC_Spe_AOPath_Engaged.png
PODC_Spe_AOPath_Engaged.png
Attachment 3: PODC_Spe_before_PODC_handoff.png
PODC_Spe_before_PODC_handoff.png
Attachment 4: AOGain3.png
AOGain3.png
Attachment 5: AOGain2.png
AOGain2.png
  4415   Fri Mar 18 17:25:21 2011 josephbUpdateCDSLockins in c1sus update, suspension screens updated

I updated our lockin simulink pieces to use the newer, more streamlined lockin piece that is currently in CDS_PARTS (with new documentation block!).  It means we are no longer passing clock signals through three levels of boxes.

In order to use the piece, you need to right click on it after copying from CDS_PARTS and go to Link Options->Disable Link.  This forces the .mdl to save all the relevant information about the block rather than just a pointer to the library.  I talked with Rolf and Alex today and we discussed setting up another model file, non-library format for putting generically useful user blocks into, rather than using the CDS_PARTS library .mdl.

The BS, ITMX, ITMY, PRM, SRM, ETMX, ETMY now have working lockins, with the input matrix to them having the 2nd input coming from LSC_IN, the 3rd from the oplev pitch, and the 4th from oplev yaw.

This necessitated a few name changes in the medm screens.  I also changed the lockin clock on/off switch to a direct amplitude entry, which turns green when a non-zero value is entered.

Currently, the Mode cleaner optic suspension screens have white lockins on them.  I started modifying a new set of screens just for them, and will modify the generate_master_screens.  Unfortunately, this requires modifying two sets of suspension screens going forward - the main interferometer optics and the MC optics.

  10818   Fri Dec 19 15:59:49 2014 JenneUpdateLSCLockloss from Wed

I swapped out one of the channels on Q's lockloss plotter - we don't need POP22Q, but I do want the PC drive.  

So, we still need to look into why the PC drive goes crazy, and if it is related to the buildup in the arms or just something intrinsic in the current FSS setup, but it looks like that was the cause of the lockloss that Q and Diego had on Wednesday.

1102929772_PCdriveRailed.png

  10783   Thu Dec 11 17:45:54 2014 ericqUpdateComputer Scripts / ProgramsLockloss plotting

 With some advice from Jamie, I've gotten the lock loss plotting script that is used at LHO working on our machines. The other night, I modified the ALSwatch.py script to log lockloss times. Tying it together, I've written a small wrapper script that grabs the last time from the lockloss log, and plots it. 

It is: scripts/LSC/LocklossData/lastlock.sh

Jamie's going to make an adjustment to the pydv codebase that will let me implement the auto y-scaling that we like. We also will need to get a feel for the right timing window, once we see what kind of delay in the ALSwatch script is typical. 

Here's an example of the output, with the window of [-10,+2] seconds from the logged GPS time:

figure.png

 

  10929   Thu Jan 22 03:21:24 2015 JenneUpdateLSCLocks with large MICH offsets

[Jenne, Diego, EricQ]

Tonight we worked on the acquisition sequence (including re-re-re-commissioning the UGF servos, hopefully for the last time...) for the PRFPMI with large MICH offsets. 

The procedure is all in the carm_up script, as far as things work.

We had some locklosses, but they were mostly due to non-carefulness on my part during the transitions between error signals, or the UGF servos getting upset because the oscillator peaks had gotten lost in the noise.  The one that I show here is our very last one of the night, where we are hitting the rails for the MICH signal, which is then causing the other loops to have to do weird things to try to compensate, and they lose lock.

Here also is a StripTool shot during that lock stretch.  I was in the middle of increasing the MICH offset to 75% of the fringe.  The yellow trace (called MICH_B_MON) is ASDC/POPDC normalized so that it always goes 0-1.  I was pleased to see that perhaps REFL11I and AS55Q are turning over, although as Q will tell us in a more detailed elog tomorrow, having a large MICH offset does weird things and moves the DARM zero-point.  So, maybe we aren't actually anywhere awesome yet. 

After some MICH offset, the maximum arm power is always going to be about 50, so arm powers of 8 or 10 equates to 100 pm.  We didn't get there tonight while on IR signals.


The locking sequence is now something like this:

  • Lock carm and darm on ALS, find resonances, move to 3 counts (roughly 3nm) offset.
  • Set PRMI up to acquire on REFL33I and ASDC/POPDC at 25% MICH fringe.  (After a while, I assume perhaps because the alignment is no longer tip-top, I have been by-hand reducing the MICH offset from -700counts which is 25% to -200counts, and then immediately putting it back to -700 after the PRMI acquires.)
  • Engage all 4 UGF servos
  • Reduce the CARM offset a bit, to 1.0 count, which gives arm powers of about 0.4 (with 50 being the max possible)
  • Transition CARM from ALS to sqrtInvTrans
  • Transition DARM from ALS to DC trans:  (TRY-TRX)/(TRX+TRY)
  • Reduce the oscillator amplitudes of the UGF servos
  • Reduce the CARM offset to powers of about 1
  • Ramp to 50% MICH fringe

After this, we tried a few times to lower the CARM offset, but kept losing lock, I think because the UGF servos went crazy.  The final lock, shown above, we lost because the MICH output was hitting the rails.

The problem with the MICH servo right now is the low SNR of the POPDC being used to normalize ASDC.  The control output is enormous, even if we have the 400Hz lowpass on.  We need to rethink our MICH servo, starting with a lower UGF, so that we're not injecting all this sensing noise all over the place. 


For tomorrow:

  • Re-look at MICH loop, to prevent sensing noise injection.
  • How does the large MICH offset affect our zero points for CARM and DARM?  Can we stay on DC transmission signals through 30 or 100 pm?
  • What to do next?  One or two of the locklosses were because the CARM detuned double cavity pole wasn't de-Q-ed enough, so still hit 0dB and created an unstable unity gain point.  Can we go to higher MICH offset, maybe 75%? 
  • Still need to figure out where our missing phase is for our LSC loops.  CARM and DARM are short on phase, and we could definitely use some more.  So, I will work on trying to give us filters that don't eat too much phase, but we still need to find that missing ~14 deg. 
  14374   Thu Dec 20 17:17:41 2018 gautamUpdateCDSLogging of new Vacuum channels

Added the following channels to C0EDCU.ini:

[C1:Vac-P1b_pressure]
units=torr
[C1:Vac-PRP_pressure]
units=torr
[C1:Vac-PTP2_pressure]
units=torr
[C1:Vac-PTP3_pressure]
units=torr
[C1:Vac-TP2_rot]
units=kRPM
[C1:Vac-TP3_rot]
units=kRPM

Also modified the old P1 channel to

[C1:Vac-P1a_pressure]
units=torr

Unfortunately, we realized too late that we don't have these channels in the frames, so we don't have the data from this test pumpdown logged, but we will have future stuff. I say we should also log diagnostics from the pumps, such as temperature, current etc. After making the changes, I restarted the daqd processes.


Things to add to ASA wiki page once the wiki comes back online:

  1. What is the safe way to clean the cryo pump if we want to use it again?
  2. What are safe conditions to turn the RGA on?
  14376   Fri Dec 21 11:11:51 2018 gautamUpdateCDSLogging of new Vacuum channels

The N2 pressure channel name was also wrong in C0EDCU.ini, so I updated it this morning to the correct name and units:

[C1:Vac-N2_pressure]
units=psi

Now it too is being recorded to frames.

  1908   Fri Aug 14 23:45:14 2009 ChrisUpdateGeneralLong Range Readout

The EUCLID-style Michelson readout is on the SP table now and is aligned.  See image below.  I took several power spectra with the plotter attached to the HP3563 (not sure if there's another way to get the data out) and I'm still waiting to calibrate (since dP/dL isn't constant as it isn't locked, this is taking a bit longer).  When put into XY mode on the oscilliscope (plotting Voltage at PD2 on the x and Voltage at PD3 on the y), a Lissajous figure as in the first plot below.  It's offset and elliptical due to imperfections (noise, dc offset, etc) but can ideally be used to calculate the L_ target mirror movement.  By rotating the first quarter wave plate by ~80.5deg counter-clockwise (fast axis was originally at Pi/8, now at 103deg), I was able to turn the Lissajous figure from an ellipse into a more circular shape, which would ideally allow for us to use a circular approximation (much simpler) in our displacement calculations.

Attachment 1: Table_Setup.png
Table_Setup.png
Attachment 2: Ellipse.jpg
Ellipse.jpg
Attachment 3: Circle.jpg
Circle.jpg
  7208   Thu Aug 16 19:12:30 2012 JenneUpdateLockingLong arm lock stretches

YARM_awesome_lock_stretch.png

After Rana and Yoichi tweaked the arm locking filters, we have had some pretty awesome lock stretches. 5-day minute trend.

  13327   Thu Sep 21 15:23:04 2017 gautamOmnistructureALSLong cable from LSC->IOO

[steve,gautam]

We laid out a 45m long BNC cable from the LSC rack to the IOO rack via overhead cable trays. There is ~5m excess length on either side, which have been coiled up and cable-tied for now. The ends are labelled "TO LSC RACK" and "TO IOO RACK" on the appropriate ends. This is to facilitate hooking up the output of the DFD for making a PM measurement of the AUX X laser. There is already a long cable that runs from the IOO rack to the X end.

  11751   Wed Nov 11 11:41:42 2015 gautamUpdateGeneralLong cable laid out for 1pps signal

In order to synchronise the FS725 Rb clock with our GPS timing signals, I laid out a longish cable running from 1X7 to the IOO rack via the overhead cable guide. There was a T-connector attached to the 1pps output of the GPS timing unit, with one of the outputs unused - I have connected one end of the cable I laid out to this output, with the other end going to the 1pps input of the FS725. I am now waiting for the FS725 to sync to the external reference, before running the calibration of the phase tracker once again using the same method detailed here, using the 10MHz output from the FS725 to serve as a reference for the Fluke RF signal generator...

  1894   Wed Aug 12 23:45:03 2009 ChrisUpdateGeneralLong range michelson

Today I set up the EUCLID long range michelson design on the SP table; It's the same as the setup posted earlier, but without the pickoff (at PD1), which can be added later, and a few other minor changes (moved lenses, mirrors, PDs - nothing major).  I hooked up the two PD's to the oscilliscope and got a readout that pointed to more power hitting PD2 than PD3.

Attachment 1: Actual_Sensor.png
Actual_Sensor.png
  11698   Mon Oct 19 15:23:22 2015 ericqUpdateLSCLonger DRFPMI lock

Here is a longer lock, about 100 seconds RF only, from later that same night. The in-loop CARM and DARM error signals have the order of magnitude of 1nm per count. 

From ~-150 to -103, we were fine tuning the ALS offsets to try and get close to the real CARM/DARM zero points then blending the RF CARM signal. 

At -100, the CARM bandwidth increases to a few kHz and stabilizes the arm powers. By -81, the error signals are all RF. At -70, I turned on the transmon QPD servos, which brought the power up a bit. 

If I recall correctly, lock was lost because I put waaaay too big of an excitation on DARM with the goal of running its UGF servo for a bit. The number I entered was appropriate for ALS, but most certainly too huge for AS55...

  13898   Wed May 30 16:12:30 2018 Jonathan HanksSummaryCDSLooking at c1oaf issues

When c1oaf starts up there are 446 gain channels that should be set to 0.0 but which end up at 1.0.  An example channel is C1:OAF-ADAPT_CARM_ADPT_ACC1_GAIN.  The safe.snap file states that it should be set to 0.  After model start up it is at 1.0.

We ran some tests, including modifying the safe.snap to make sure it was reading the snap file we were expecting.  For this I set the setpoint to 0.5.  After restart of the model we saw that the setpoint went to 0.5 but the epics value remained at 1.0.  I then set the snap file back to its original setting.  I ran the epics sequencer by hand in a gdb session and verified that the sequencer was setting the field to 0.  I also built a custom sequencer that would catch writes by the sdf system to the channel.  I only saw one write, the initial write that pushed a 0.  I have reverted my changes to the sequencer.

The gain channel can be caput to the correct value and it is not pushed back to 1.0.  So there does not appear to be a process actively pushing the value to 1.0.  On Rolfs sugestion we ran the sequencer w/o the kernel object loaded, and saw the same behavior.

This will take some thought.

  5864   Thu Nov 10 16:44:54 2011 MirkoUpdateAdaptive FilteringLooking into MC_F & PSL misalignment

 [Den, Mirko]

While doing the things below we accidentally misaligned the PSL laser. Thanks to Suresh and Jenne for realigning!!

There are a lot of strange features in MC_F (see for example http://nodus.ligo.caltech.edu:8080/40m/5738 )
To get some better understanding of the signals in the control loop we looked some more into what happens to the MC feedback signal after it exits the MC servo board (D040180 see DCC).

10112011076.jpg
The MC_F signal is actually the servo signal: http://nodus.ligo.caltech.edu:8080/40m/5695
The Thorlabs temperature controller is actually used in the PZT path!

 We measured the LP filter in the PZT path (that is kind of mislabeled as temp.)

10112011073.jpg

 

  5867   Thu Nov 10 22:00:38 2011 MirkoUpdateAdaptive FilteringLooking into MC_F & PSL misalignment

Quote:

 [Den, Mirko]

While doing the things below we accidentally misaligned the PSL laser. Thanks to Suresh and Jenne for realigning!!

There are a lot of strange features in MC_F (see for example http://nodus.ligo.caltech.edu:8080/40m/5738 )
To get some better understanding of the signals in the control loop we looked some more into what happens to the MC feedback signal after it exits the MC servo board (D040180 see DCC).

10112011076.jpg
The MC_F signal is actually the servo signal: http://nodus.ligo.caltech.edu:8080/40m/5695
The Thorlabs temperature controller is actually used in the PZT path!

 We measured the LP filter in the PZT path (that is kind of mislabeled as temp.)

10112011073.jpg

 

 

We looked into the signal from the MC servo board at different position at the PSL table.


We looked into the FB going into the temp. and PZT parts of the FB.
Temp.:
Screenshot.png

PZT:

Screenshot-1.png
We also looked at the signal in just in front of the FSS box No idea why the elog doesn't preview these pdfs.

Signal_at_MC_servo_board_and_PSL_table_2_1.pdf

Signal_at_MC_servo_board_and_PSL_table_2_2.pdf

Signal_at_MC_servo_board_and_PSL_table_2_3.pdf

Signal_at_MC_servo_board_and_PSL_table_2_4.pdf
Lots of extra noise there. We will check out where that comes from.

  15276   Fri Mar 13 20:00:50 2020 JonUpdateComputersLoopback monitoring for slow machines

Summary

Today I finished implementing loopback monitors of the up/down state of the slow controls machines. They are visible on a new MEDM screen accessible from Sitemap > CDS > Slow Machine Status (pictured in attachment 1). Each monitor is a single EPICS binary channel hosted by the slow machine, which toggles its state at 1 Hz (an alive "blinker"). For each machine, the monitor is defined by a separate database file named c1[machine]_state.db located in the target directory.

This is implemented for all upgraded machines, which includes every slow machine except for c1auxey. This is the next and final one slated for replacement.

Implementation

The blinkers are currently implemented as soft channels, but I'd like to ultimately convert them to hard channels using two sinking/sourcing BIO units. This will require new wiring inside each Acromag chassis, however. For now, as soft channels, the monitors are sensitive to a failure of the host machine or a failure of the EPICS IOC. As hard channels, they will additionally be sensitive to a failure of the secondary network interface, as has been known to happen.

Each slow machine's IOC had to be restarted this afternoon to pick up the new channels. The IOCs were restarted according to the following procedure.

c1auxex

  • Disabled OPLEV servos on ETMX
  • Zeroed slow biases
  • Disabled watchdog
  • Restarted IOC
  • Reverted 1-3

​c1vac

  • Closed V1, VM1
  • Restarted IOC
  • Returned valves to original state

c1psl

  • Disabled IMC autolocker
  • Closed PSL shutter
  • Restarted IOC
  • Reverted 1-2

c1iscaux

  • ​Restarted IOC

c1susaux

  • Disabled IMC autolocker
  • Closed shutter
  • Disabled OPLEV servos on: MC1, MC2, MC3, BS, ITMX, ITMX, PRM, SRM
  • Zeroed slow biases
  • Disabled watchdogs
  • Restarted IOC
  • Reverted 1-5

The intial recovery of c1susaux did not succeed. Most visibly, the alignment state of the IFO was not restored. After some debugging, we found that the restart of the modbus service was partially failing at the final burt-restore stage. The latest snapshot file /opt/rtcds/caltech/c1/burt/autoburt/latest/c1susaux.snap was not found. I manually restored a known good snapshot from earlier in the day (15:19) and we were able to relock the IMC and XARM. GV and I were just talking earlier today about eliminating these burt-restores from the systemd files. I think we should.

Attachment 1: Screen_Shot_2020-03-13_at_7.59.55_PM.png
Screen_Shot_2020-03-13_at_7.59.55_PM.png
  718   Tue Jul 22 22:25:31 2008 ranaUpdateLSCLooptickle for existing 40m
John and I have adapted the Stefan-Looptickle model of the 40m upgrade to have the parameters of the old one.
(old one = what we have had for the last 4 years).

Its in the /cvs/cds/caltech/iscmodeling directory on the CDS computers but you can also check it out from the
MIT CVS repo; its part of the whole shebang.

It makes the attached theoretical NB. Feel free to modify it.
Attachment 1: nb.png
nb.png
  14307   Mon Nov 19 22:01:50 2018 gautamUpdateVACLoose nut on valve

As I was turning off the lights in the VEA, I heard a rattling sound from near the PSL enclosure. I followed it to a valve - I couldn't see a label on this valve in my brief effort to find one, but it is on the south-west corner of the IMC table, so maybe VABSSCI or VABSSCO? The power cable is somehow spliced with an attachment that looks to be bringing gas in/out of the valve (See Attachment #1), and the nut on the bottom was loose, the whole power cable + mettal attachment was responsible for the rattling. I finger-tightened the nut and the sound went away.

Attachment 1: IMG_7171.JPG
IMG_7171.JPG
  11876   Fri Dec 11 23:12:09 2015 KojiSummaryCOCLoss map measurement document

Yutaro left detailed slides for his loss map measurement

https://dcc.ligo.org/LIGO-G1501547

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