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  16343   Mon Sep 20 12:20:31 2021 PacoSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

[yehonathan, paco, anchal]

We attempted to find any symptoms for actuation problems in the PRMI configuration when actuated through BS and PRM.

Our logic was to check angular (PIT and YAW) actuation transfer function in the 30 to 200 Hz range by injecting appropriately (f^2) enveloped excitations in the SUS-ASC EXC points and reading back using the SUS_OL (oplev) channels.

From the controls, we first restored the PRMI Carrier to bring the PRM and BS to their nominal alignment, then disabled the LSC output (we don't need PRMI to be locked), and then turned off the damping from the oplev control loops to avoid supressing the excitations.

We used diaggui to measure the 4 transfer functions magnitudes PRM_PIT, PRM_YAW, BS_PIT, BS_YAW, as shown below in Attachments #1 through #4. We used the Oplev calibrations to plot the magnitude of the TFs in units of urad / counts, and verified the nominal 1/f^2 scaling for all of them. The coherence was made as close to 1 as possible by adjusting the amplitude to 1000 counts, and is also shown below. A dip at 120 Hz is probably due to line noise. We are also assuming that the oplev QPDs have a relatively flat response over the frequency range below.

Attachment 1: PRM_PIT_ACT_TF.pdf
Attachment 2: PRM_YAW_ACT_TF.pdf
Attachment 3: BS_PIT_ACT_TF.pdf
Attachment 4: BS_YAW_ACT_TF.pdf
  16345   Mon Sep 20 14:22:00 2021 ranaSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

I suggest plotting all the traces in the plot so we can see their differences. Also remove the 1/f^2 slope so that we can see small differences. Since the optlev servos all have low pass filters around 15-20 Hz, its not necessary to turn off the optlev servos for this measurement.

I think that based on the coherence and the number of averages, you should also be able to use Bendat and Piersol so estimate the uncertainy as a function of frequency. And we want to see the comparison coil-by-coil, not in the DoF basis.

4 sweeps for BS and 4 sweeps for PRM.

  16358   Thu Sep 23 15:29:11 2021 PacoSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

[Anchal, Paco]

We had a second go at this with an increased number of averages (from 10 to 100) and higher excitation amplitudes (from 1000 to 10000). We did this to try to reduce the relative uncertainty a-la-Bendat-and-Pearsol

\delta G / G = \frac{1}{\gamma \sqrt{n_{\rm avg}}}

where \gamma, n_{\rm avg} are the coherence and number of averages respectively. Before, this estimate had given us a ~30% relative uncertainty and now it has been improved to ~ 10%. The re-measured TFs are in Attachment #1. We did 4 sweeps for each optic (BS, PRM) and removed the 1/f^2 slope for clarity. We note a factor of ~ 4 difference in the magnitude of the coil to angle TFs from BS to PRM (the actuation strength in BS is smaller).

For future reference:

With complex G, we get complex error in G using the formula above. To get uncertainity in magnitude and phase from real-imaginary uncertainties, we do following (assuming the noise in real and imaginary parts of the measured transfer function are incoherent with each other):
G = \alpha + i\beta

\delta G = \delta\alpha + i\delta \beta

\delta |G| = \frac{1}{|G|}\sqrt{\alpha^2 \delta\alpha^2 + \beta^2 \delta \beta^2}

\delta(\angle G) = \frac{1}{|G|^2}\sqrt{\alpha^2 \delta\alpha^2 + \beta^2 \delta\beta^2} = \frac{\delta |G|}{|G|}

Attachment 1: BS_PRM_ANG_ACT_TF.pdf
  16371   Fri Oct 1 14:25:27 2021 yehonathanSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

{Paco, Yehonathan, Hang}

We measured the sensing PRMI sensing matrix. Attachment 1 shows the results, the magnitude of the response is not calibrated. The orthogonality between PRCL and MICH is still bad (see previous measurement for reference).

Hang suggested that since MICH actuation with BS and PRM is not trivial (0.5*BS - 0.34*PRM) and since PRCL is so sensitive to PRM movement there might be a leakage to PRCL when we are actuating on MICH. So there may be a room to tune the PRM coefficient in the MICH output matrix.

Attachment 2 shows the sensing matrix after we changed the MICH->PRM coefficient in the OSC output matrix to -0.1.

It seems like it made things a little bit better but not much and also there is a huge uncertainty in the MICH sensing.

Attachment 1: MICH_PRM_-0.34.png
Attachment 2: MICH_PRM_-0.1.png
  16374   Mon Oct 4 16:00:57 2021 YehonathanSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

{Yehonathan, Anchel}

In an attempt to fix the actuation of the PRMI DOFs we set to modify the output matrix of the BS and PRM such that the response of the coils will be similar to each other as much as possible.

To do so, we used the responses at a single frequency from the previous measurement to infer the output matrix coefficients that will equilize the OpLev responses (arbitrarily making the LL coil as a reference). This corrected the imbalance in BS almost completely while it didn't really work for PRM (see attachment 1).

The new output matrices are shown in attachment 2-3.

Attachment 1: BS_PRM_ANG_ACT_TF_20211004.pdf
BS_PRM_ANG_ACT_TF_20211004.pdf BS_PRM_ANG_ACT_TF_20211004.pdf BS_PRM_ANG_ACT_TF_20211004.pdf BS_PRM_ANG_ACT_TF_20211004.pdf
Attachment 2: BS_out_mat_20211004.txt
9.839999999999999858e-01 8.965770586285104482e-01 9.486710352885977526e-01 3.099999999999999978e-01
1.016000000000000014e+00 9.750242104232501594e-01 -9.291967546765563801e-01 3.099999999999999978e-01
9.839999999999999858e-01 -1.086765190351774768e+00 1.009798093279114628e+00 3.099999999999999978e-01
1.016000000000000014e+00 -1.031706735496689786e+00 -1.103142995587099939e+00 3.099999999999999978e-01
0.000000000000000000e+00 0.000000000000000000e+00 0.000000000000000000e+00 1.000000000000000000e+00
Attachment 3: PRM_out_mat_20211004.txt
1.000000000000000000e+00 1.033455230230304611e+00 9.844796282226820905e-01 0.000000000000000000e+00
1.000000000000000000e+00 9.342329554807877745e-01 -1.021296201828568506e+00 0.000000000000000000e+00
1.000000000000000000e+00 -1.009214777246558503e+00 9.965113815550634691e-01 0.000000000000000000e+00
1.000000000000000000e+00 -1.020129700278567197e+00 -9.973560027273553619e-01 0.000000000000000000e+00
0.000000000000000000e+00 0.000000000000000000e+00 0.000000000000000000e+00 1.000000000000000000e+00
  16375   Mon Oct 4 16:10:09 2021 ranaSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

not sure that this is necessary. If you look at teh previous entries Gautam made on this topic, it is clear that the BS/PRM PRMI matrix is snafu, whereas the ITM PRMI matrix is not.

Is it possible that the ~5% coil imbalance of the BS/PRM can explain the observed sensing matrix? If not, then there is no need to balance these coils.

  16383   Tue Oct 5 20:04:22 2021 PacoSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

[Paco, Rana]

We had a look at the BS actuation. Along the way we created a couple of issues that we fixed. A summary is below.

  1. First, we locked MICH. While doing this, we used the /users/Templates/ndscope/LSC/MICH.yml ndscope template to monitor some channels. I edited the yaml file to look at C1:LSC-ASDC_OUT_DQ instead of the REFL_DC. Rana pointed out that the C1:LSC-MICH_OUT_DQ (MICH control point) had a big range (~ 5000 counts rms) and this should not be like that.
  2. We tried to investigate the aforementioned thing by looking at the whitening / uwhitening filters but all the slow epics channels where "white" on the medm screen. Looking under CDS/slow channel monitors, we realized that both c1iscaux and c1auxey were weird, so we tried telnet to c1iscaux without success. Therefore, we followed the recommended wiki procedure of hard rebooting this machine. While inside the lab and looking for this machine, we touched things around the 'rfpd' rack and once we were back in the control room, we couldn't see any light on the AS port camera. But the whitening filter medm screens were back up.
  3. While rana ssh'd into c1auxey to investigate about its status, and burtrestored the c1iscaux channels, we looked at trends to figure out if anything had changed (for example TT1 or TT2) but this wasn't the case. We decided to go back inside to check the actual REFL beams and noticed it was grossly misaligned (clipping)... so we blamed it on the TTs and again, went around and moved some stuff around the 'rfpd' rack. We didn't really connect or disconnect anything, but once we were back in the control room, light was coming from the AS port again. This is a weird mystery and we should systematically try to repeat this and fix the actual issue.
  4. We restored the MICH, and returned to BS actuation problems. Here, we essentially devised a scheme to inject noise at 310.97 Hz and 313.74. The choice is twofold, first it lies outside the MICH loop UGF (~150 Hz), and second, it matches the sensing matrix OSC frequencies, so it's more appropriate for a comparison.
  5. We injected two lines using the BS SUS LOCKIN1 and LOCKIN2 oscilators so we can probe two coils at once, with the LSC loop closed, and read back using the C1:LSC-MICH_IN1_DQ channel. We excited with an amplitude of 1234.0 counts and 1254 counts respectively (to match the ~ 2 % difference in frequency) and noted that the magnitude response in UR was 10% larger than UL, LL, and LR which were close to each other at the 2% level.


After rana left, I did a second pass at the BS actuation. I took TF measurements at the oscilator frequencies noted above using diaggui, and summarize the results below:

TF UL (310.97 Hz) UR (313.74 Hz) LL (310.97 Hz) LR (313.74 Hz)
Magnitude (dB) 93.20 92.20 94.27 93.85
Phase (deg) -128.3 -127.9 -128.4 -127.5

This procedure should be done with PRM as well and using the PRCL instead of MICH.

  16385   Wed Oct 6 15:39:29 2021 AnchalSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

Note that your tests were done with the output matrix for BS and PRM in the compensated state as done in 40m/16374. The changes made there were supposed to clear out any coil actuation imbalance in the angular degrees of freedom.

  16393   Tue Oct 12 11:32:54 2021 YehonathanSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

Late submission (From Thursday 10/07):

I measured the PRMI sensing matrix to see if the BS and PRMI output matrices tweaking had any effect.

While doing so, I noticed I made a mistake in the analysis of the previous sensing matrix measurement. It seems that I have used the radar plot function with radians where degrees should have been used (the reason is that the azimuthal uncertainty looked crazy when I used degrees. I still don't know why this is the case with this measurement).

In any case, attachment 1 and 2 show the PRMI radar plots with the modified output matrices and and in the normal state, respectively.

It seems like the output matrix modification didn't do anything but REFL55 has good orthogonality. Problem gone??

Attachment 1: modified_output_matrices_radar_plots.png
Attachment 2: normal_output_matrices_radar_plots.png
  16394   Tue Oct 12 16:39:52 2021 ranaSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

should compare side by side with the ITM PRMI radar plots to see if there is a difference. How do your new plots compare with Gautam's plots of PRMI?

  16402   Thu Oct 14 13:40:49 2021 YehonathanSummarySUSPRM and BS Angular Actuation transfer function magnitude measurements

Here is a side by side comparison of the PRMI sensing matrix using PRM/BS actuation (attachment 1) and ITMs actuation (attachment 2). The situation looks similar in both cases. That is, good orthogonality on REFL55 and bad seperation in the rest of the RFPDs.


should compare side by side with the ITM PRMI radar plots to see if there is a difference. How do your new plots compare with Gautam's plots of PRMI?


Attachment 1: BSPRM_Actuation_Radar_plots.png
Attachment 2: ITM_Actuation_Radar_plots.png
  5618   Tue Oct 4 19:31:17 2011 kiwamuUpdateSUSPRM and BS oplev laser died

The He-Ne laser which has been used for the PRM and BS oplevs were found to be dead.

According to the trend data shown below, it became dead during the dolphin issue.

(During the dolphin issue the output from the oplev QPDs are digitally zero)


  5620   Wed Oct 5 11:33:25 2011 steveUpdateSUSPRM and BS oplev laser replaced


JDSU 1103P died after 4 years of service. It was replaced with new identical head of 2.9 mW output. The power supply was also changed.

The return spots of 0.04 mW  2.5 mm diameter on qpds are BS  3,700 counts and PRM 4,250 counts.


  11227   Mon Apr 20 16:42:48 2015 steveUpdateSUSPRM and BS oplev laser replaced

The laser below is dead. JDSU 1103P, SN P845655 lived for 3.5 years.



JDSU 1103P died after 4 years of service. It was replaced with new identical head of 2.9 mW output. The power supply was also changed.

The return spots of 0.04 mW  2.5 mm diameter on qpds are BS  3,700 counts and PRM 4,250 counts.


It was replaced by JDSU P/N 22037130,( It has a new name for 1103P Uniphase ) sn P919639 of mfg date 12-2014

Beam shape at 5 m nicely round. Output power 2.8 mW of 633 nm

BS spot size on qpd ~1 mm &  60 micro W

PRM spot size on qpd ~1 mm & 50 micro W

Attachment 1: newOplevLaser.png
  11246   Fri Apr 24 23:40:15 2015 ranaUpdateSUSPRM and BS oplev laser replaced

Recently, Steve replaced the HeNe which was sourcing the BS & PRM OL. After replacement, no one checked the beam sizes and we've been living with a mostly broken BS OL. The beam spot on the QPD was so tiny that we were seeing the 'beam is nearly the size of the segment gap' effect.

Today I removed 2 of the lenses which were in the beam path: one removed from the common PRM/BS path, and one removed from the PRM path. The beams on both the BS & PRM got bigger. The BS beam is bigger by a factor of 7. I've increased the loop gains by a factor of 6 and now the UGFs are ~6 Hz. The loop gains were much too high with the small beam spots that Steve had left there. I would prefer for the beams to be ~1.5-2x smaller than they are now, but its not terrible.

Many of the mounts on the table are low quality and not constructed stably. One of the PRM turning mirror mounts twisted all the way around when I tried to align it. This table needs some help this summer.

In the future: never try locking after an OL laser change. Always redo the telescope and alignment and check the servo shape before the OL job is done.

Also, I reduced the height of the RG3.3 in the OL loops from 30 to 18 dB. The BS OL loops were conditionally stable before and thats a no-no. It makes it oscillate if it saturates.

Attachment 1: BSOL.pdf
  3278   Fri Jul 23 15:54:38 2010 kiwamuUpdateSUSPRM and TT installed

[ Jenne, Koji and Kiwamu]

 We have installed the PRM and the tip-tilt (TT) in the BS chamber.

We have started the in-vac work which takes about a week.

Today's mission was dedicated to installing the PRM and two TTs, one for the PRC and the other for the SRC, on the BS table in the chamber.

The work has been smoothly performed and we succeeded in installation of the PRM and a TT for the PRC.

But unfortunately the other TT got broken during its transportation from Bob's clean room.


 (what we did)

 (1) opened the light door of the BS chamber.

 (2) moved the BS tower to the right position according to Koji's layout drawing.

    - Prior to this work we screwed down the earthquake stops so that the mirror is fixed to the tower. Also we disabled the watchdog.

    - When moving it we used an allen key as a lever with an screw as a fulcrum. This idea was suggested by Jenne and it really worked well.

     The reason why we used this technique is that if we slide the tower by hands the tower can't go smoothly and it may sometimes skips.

     After that we checked the postion from some reference screw holes by using a caliper and we made sure that it was on the right position.

 (3) removed all of the square-shaped mirrors.

    - After this removal the mirrors were wrapped by aluminum foils and put in a usual clear box.

 (4) removed some optics because they had made the chamber space crowded.

    - These were also wrapped by aluminum foils and put in the box. Later we will put them back to the BS table.

 (5) brought the PRM tower from the Bob's clean room  and put it on the BS table.

   - The position of the PRM were coarsely aligned since we still don't have any 1064 beam going through the PRM.

 (6) brought two TTs also from Bob's clean room and put one of the TTs on the table.  

   - The position of the installed TT was coarsely adjusted. 

   - After we brought them we removed the aluminum foils covering the TTs and we found the wire of a TT got broken.

     It may have been damaged during its transportation from Bob's room because it was fine before the transportation.

 (7) closed the door


(the next things to do)

  * Installation of the OSEMs to the PRM

  * Installation of the pick off mirror and its associated optics

  * Arrangement of  the pzt mirror


Attachment 1: DSC_2275.JPG
  3281   Fri Jul 23 18:55:25 2010 kiwamuUpdateSUSPRM and TT installed

I updated the last entry.

  8236   Tue Mar 5 23:37:11 2013 yutaUpdateSUSPRM angular motion spectra

I measured PRM angular motion spectra (in daytime today).
PRM angular motion is ~ 10 urad in RMS when undamped and ~1 urad in RMS when damped.
If PR2/PR3 angular motions are something like this, and their motion are not enhanced when PRC is locked, measured g-factor of PRC looks OK. But considering the error we have, maybe we are not OK yet. We need calculation.


  3746   Wed Oct 20 18:17:35 2010 Suresh, JenneUpdateSUSPRM assembly

We have positioned the guide rod and the wire-stand-off on the optic in the axial direction. 

We have selected six magnets whose magnetic strength is +/-5% of their mean strength (180 Gauss).  The measurement was made as follows:

1) each magnet was placed on its  end, on the top of a beaker held upside down. 

2) The Hall probe was placed directly under the magnet touching the glass from the other side (the inside of the beaker). 

This ensures that the relative position of the magnet and the probe remains fixed during a measurement.  And ensures that their separation is the same for each of the magnets tested. 

With this procedure the variation in the measured B field is less than +/- 10% in the sample of magnets tested.

  3824   Fri Oct 29 14:16:26 2010 JenneUpdateSUSPRM baking

[Suresh, Jenne]

We took a look-see at the PRM after the gluing from last night.  The balance is still okay.  The reflected beam is a teeny bit below the laser aperture (center of the beam maybe ~2mm below, so ~1mRad low).  This is within our okay range, since the DC offset that the OSEMs will give will be even more, and the coils can definitely handle this kind of offset.

We took the optic out of the tower, and gave it to Bob and Daphen to bake over the weekend.

  15880   Mon Mar 8 17:09:29 2021 gautamUpdateSUSPRM coil actuators heavily imbalanced

I realized I hadn't checked the PRM actuator as thoroughly as I had the others. I used the Oplev as a sensor to check the coil balancing, and I noticed that while all 4 coils show up with the expected 1/f^2 profile at the Oplev error point, the actuator gains seem imbalanced by a factor of ~5. The phase isn't flat because of some filters in the Oplev electronics I guess. The Oplev loops were disabled for the measurement, and the excitations were small enough that the beam stayed reasonably well centered on the QPD throughout. This seems very large to me - the values in the coil output filter gains lead me to expect more like a ~10% mismatch in the actuation strenghts, and similar tests on other optics in the past, e.g. ETMY, have yielded much more balanced results. I'm collecting some free-swinging PRM data now as an additional check. I verified that all the coils seem actuatable at least, by applying a 500 ct step at the offset of the coil output FM, and saw that the optic moved (it was such a test that revealed that MC1 had a busted actuator some time ago). If the eigenmode spectra look as expected, I think we can rule out broken magnets, but I suppose the magnets could still be not well matched in strength?

Attachment 1: PRMact.pdf
  8093   Sat Feb 16 17:27:26 2013 yutaUpdateSUSPRM coil balanced

PRM coil gains and f2a filters are adjusted for PRMI work.
It seems like UR/LL coil gains were ~10 % larger than others, and f2a filters changed by few %.

What I did:
  1. Tried to lock PRMI but when I turn on PRCL lock, PRM reflection looked like it tends to go up and left in REFL camera (last night).

  2. So, I set up PRM oplev back, by steering PRM oplev mirrors on the BS table (last night).

  3. Turned PRM oplev sero on, f2a filters off, and ran

> /opt/rtcds/caltech/c1/scripts/SUS/F2P_LOCKIN.py -o PRM

  I had to fix F2P_LOCKIN.py because it assumed some OUTPUT buttons in LOCKIN1 filters to be ON.
  Also, I had to restore filters in LOCKIN1 (8.5 Hz bandpass filter etc.) because their names were changed. To do this, I copied filters needed from /opt/rtcds/caltech/c1/chans/filter_archive/c1sus/C1SUS_110916_162512.txt, renamed LOCKIN1_(I|Q|SIG) with LOCKIN1_DEMOD_(I|Q|SIG), and pasted to the current filter bank file. I checked that they look OK with foton after editing the file.

  This measurement takes about 30 minutes. I ran several times to check consistency. There was ~ 0.1 % standard deviation for the measurement results.

  4. By putting measured coupling coefficients and PRM pendulum frequency (f0=0.993 Hz) to /opt/rtcds/caltech/c1/scripts/SUS/F2Pcalc.py, I got new f2a filters.

  5. Overwrote f2a filters in C1:SUS-PRM_TO_COIL_(1-4)_1 FM1 with new ones, and turned  new f2a filters on.

  Below is the DC gain adjustment result from F2P_LOCKIN.py;

multiplier factors are :
UL = 1.141525
UR = 0.879997
LR = 1.117484
LL = 0.860995
Set C1:SUS-PRM_ULCOIL_GAIN to 1.04990177238
Set C1:SUS-PRM_URCOIL_GAIN to -0.983396190716
Set C1:SUS-PRM_LRCOIL_GAIN to 0.954304254663
Set C1:SUS-PRM_LLCOIL_GAIN to -0.971356852259

  So, UR/LL coil gains somehow got ~10 % larger than other two since last coil balancing.

  Measured coupling coefficients from F2P_LOCKIN.py were

- measured coupling coefficients are :
P2P(POS=>PIT) = 0.014993
P2Y(POS=>YAW) = 0.001363

  New f2a filters are plotted below. They look fairly different compared with previous ones.


We need better F2P_LOCKIN.py:
  Some one should make F2P_LOCKIN.py better. The main problem is the sudden gain change when starting diagonalization at low frequency. It sometimes trips off the watchdog.

Some elogs related:
  Kiwamu made f2a filters in Sep 2011: elog #5417
  Koji adjusting DC gains in Jan 2013: elog #7969

  8096   Sun Feb 17 19:27:19 2013 ranaUpdateSUSPRM coil balanced

 I will check out the AS55 situation tomorrow. Just put it on my desk.

MC Autolocker was disabled - I enabled it.

For the F2P.py, you should look at how we did this with the script written 8 years ago in csh. There we stored the initial values in a file (so they don't get blow away if someone does CTRL-C). Your python script should have a trap for SIGINT so that it dies gracefully by restoring the initial values. In order to have the smooth value adjustment, you must first set the TRAMP field for all the coil gains to 2 and then switch. Make sure that the lockin ignores the first few seconds of data after making this switch or else it will be hugely biased by this transient.

For the PRM OL use as a F2A reference, you also have to take into account that the OL beam is hitting the PRM surface at non-normal incidence. IF it is a large angle, there will be a systematic error in the setting of the F2Y values.

  8065   Tue Feb 12 00:14:00 2013 yutaUpdateLockingPRM coil balancing

We tried to lock half-PRC tonight, but we couldn't. Why?? I could lock yesterday.
It locks for ~ 1 sec, but it beam spot motion freaks out mainly in yaw.
I tried to balance PRM coils, but oplev beam was clipped by MMT1......

What I did:
  1. Found elog #5392 and found F2P_LOCKIN.py

  2. Modified F2P_LOCKIN.py because LOCKIN channel names are some how changed like this;


  3. Running

/opt/rtcds/caltech/c1/scripts/SUS/F2P_LOCKIN.py -o PRM

  should adjust (UL|UR|LR|LL)COIL_GAINs by putting some gain imbalance and shaking the mirror in different frequencies. It uses LOCKIN to OL(PIT|YAW).

  4. Since there was no PRM oplev beam coming out from the vacuum, I quickly looked into BS-PRM chamber. Oplev beam was clipped by MMT1. If I adjust PRM slider values to avoid clipping, the beam will be clipped by mirrors on oplev table. What happened to the PRM oplev?

  5. I also made bunch of /opt/rtcds/userapps/trunk/sus/c1/medm/templates/SUS_SINGLE_LOCKIN(1|2)_DEMOD_(I|Q|SIG).adl because there were missing screens.

 We need to restore the PRM oplev and balance the coils. See, also, elog #7679

  7959   Tue Jan 29 21:07:48 2013 JenneUpdateLockingPRM coils need diagonalizing


 [Jenne, Jamie]

We tried actuating on PRM so that we go through fringes in a known, linear way.  We used C1:SUS-PRM_LSC_EXC and awggui.  It seems that we get a lot of angular motion when we actuate....we need to look into this tomorrow.

EDIT/UPDATE:  Last night we tried several combinations of frequency and amplitude, but just for an idea,  we were using 2Hz, 1000cts.  Using Kiwamu's calibration in elog 5583 for the PRM actuator of 2e-8/f^2 m/cts, this means that we were pushing ~5nm.  But when we pushed much harder (larger amplitude) than that, we saw angular fringing. 

  7969   Wed Jan 30 19:34:17 2013 JenneUpdateLockingPRM coils need diagonalizing

[Koji, Jamie, Jenne]

Koji did this, while we actuated on PRM in pos, and watched the oplev.  Empirically, he found the following values for the POS column of the output matrix:

UL = 1.020

UR = 0.990

LL = 1.000

LR = 0.970

SD = 0.000

(The nominal values are all +1, except for Side, which is 0). 

Actuation of PRM was through C1:SUS-PRM_LSC_EXC, f=0.1Hz, A=100 counts.


Ed by KA:
This means UL and UR are increased by 2% and UR and LR are decreased by 3%. More precisely UR should be 1.02*0.97.
This is just a quick hack which works only for the DC.

  10691   Mon Nov 10 07:36:35 2014 SteveUpdateSUSPRM damping recovered

PRM sus damping recovered and PMC locked.

  4876   Fri Jun 24 07:40:23 2011 steveUpdateSUSPRM damping restored

The PRM sus damping restored. C1:SUS-PRM_SDPD_VAR is still 20-30mV and going up.  Side gain  turned on. This pulled it down to 5-8 mV

Why is the side osem sensing voltage 4.4V ? It can not be higher than ~2.4V.......something is rotten in the state of Denmark?

Edit by KI:

 It's because Valera increased the transimpedance gain of the PRM SIDE OSEM to match the signal level to the new ADC range (#3913 ).

  4938   Tue Jul 5 13:35:56 2011 steveUpdateSUSPRM damping restored

The PRM sus damping was restored. It's side rms motion came down from 35 to 4 mV immediately.      Lab   air quality is back to normal.


  4987   Tue Jul 19 09:19:14 2011 steveUpdateSUSPRM damping restored

The PRM watchdogs were tripped. The side was kicked up to 180mV Damping was restored.

  5403   Wed Sep 14 07:51:20 2011 steveUpdateSUSPRM damping restored

The PRM damping was restored at side sensor var 1050

  5415   Thu Sep 15 07:28:08 2011 steveUpdateSUSPRM damping restored


The PRM damping was restored at side sensor var 1050

 The PRM sus damping restored.

  5909   Wed Nov 16 10:25:57 2011 steveUpdateSUSPRM damping restored

The  PRM lost damping about a day ago. It was restored.

  7333   Tue Sep 4 10:29:41 2012 SteveUpdateSUSPRM damping restored
  7544   Mon Oct 15 08:08:33 2012 steveUpdateSUSPRM damping restored





Yuta claims he fixed the PRM oplev by centering it the other day, but no one has left it on and watched it for a long while, to make sure it's okay.  We watched it now for ~2 min, and it was good, but we're leaving the oplevs off anyway for the night.  Tomorrow we should restore PRM (it's currently restored), turn on the oplevs, and let it sit to make sure it doesn't go crazy.


 PRM oplev servo was turned on with PITgain 0.5  and YAWgain  -0.7

Note: gain settings were PIT  1.0  and  YAW --0.5   on Jun 1, 2012 that I measured Feb 23, 2012

 It is still oscillating. Gains turned down to zero.

 Earthquake test our suspensions            PRM damping restored.             Oplev servo gains turned to zero.

 The PRM damping restored. Oplev  PIT gain  0.15 and YAW  gain   -0.3 turned to zero.

  7781   Tue Dec 4 10:51:10 2012 SteveUpdateSUSPRM damping restored

PRM oplev gains set to zero from PIT 0.15 and YAW -0.3 and damping restored

  7903   Wed Jan 16 08:29:45 2013 SteveUpdateSUSPRM damping restored

PRM oplev servo turned off.  OLPIT servo gain 0.15 and OLYAW  -0.3 set to ZERO.  PRM damping restored

  10466   Mon Sep 8 07:50:40 2014 SteveUpdateSUSPRM damping restored
  10506   Mon Sep 15 15:52:44 2014 SteveUpdateSUSPRM damping restored

 The PRM side was kicked up

  11339   Mon Jun 1 08:32:14 2015 SteveUpdateSUSPRM damping restored

Local earthquake 3.8 Mag tripped only PRM

Vac monitor is not communicating.

PSL HEPA turned on

Attachment 1: indio3.8Meq.png
  11948   Mon Jan 25 08:36:46 2016 SteveUpdateSUSPRM damping restored

PRM suspension damping restored after 4.1 Mag Ludlow earthquake.


Attachment 1: EQ4.1mLudlow.png
Attachment 2: EQ7.1mAlaska_4.1mLudlow.png
Attachment 3: 7.1_4.1.png
  12050   Mon Mar 28 08:30:09 2016 SteveUpdateSUSPRM damping restored

Recent  EQ 4.8 mag San Felipe, Mexico trips PRM sus damping.

PRM damping restored. PMC locked.

Attachment 1: shaking.png
  12541   Mon Oct 10 09:31:25 2016 SteveUpdateSUSPRM damping restored

Local earth quake 3.7 mag  trips PRM

ETMY_UL glitch

What about the MC?


Attachment 1: 3.7mLomaLinda.png
Attachment 2: ETMY_UL_glitch.png
Attachment 3: MC_glitcing?.png
  6764   Wed Jun 6 09:27:09 2012 steveUpdateSUSPRM damping restored


What not to do:

The PRM oplev servo was left on and it was driving this oscillation overnight.

 Oplev servo turned off and sus damping restored. What is kicking up the PRM?

Attachment 1: PRMwhat.png
  9140   Thu Sep 19 10:24:58 2013 SteveUpdatePEMPRM damping restored after earth quake

Local m3.8 eq shakes PRM lose.

Attachment 1: eq3.8mLaVerne.png
  837   Thu Aug 14 19:35:54 2008 JenneSummaryIOOPRM in the chamber, ready to pump!
Rob, Yoichi, Jenne, Steve

Summary: Everything is back in the chamber, we just need to put on the big doors, and start pumping in the morning.

After letting the PRM's standoff epoxy cure overnight, it was time to put the optic back in the BS Chamber. Rob put the optic cage back in the chamber, as close to the guide points that Rana had placed as possible. A handy technique was discovered for pushing the cage into place: put a long screw into the table, leaving an inch or so above the table, then use that as a push-off point so that you can push the base of the cage with your thumb. According to Rob, this is probably just about as effective as using a pusher-screw.

The guides were helpful in getting the PRM back to its original position, but one of them was placed in such a way that it could move when pushed against. The clamp that was used as a guide point was placed with one of the screws half on the edge of a hole, so that when the cage was pushed against the guide point, that screw could wiggle around, causing the clamp to rotate thus no longer being a definite guide point.

Just after putting the PRM in place, Rob found the standoff that had gone missing. (see elog #835)

Once the PRM was back in place, we put the OSEMs back, and reinstalled the satellite boxes that had been removed (PRM's, which Ben has fixed - an op-amp was blown, and BS's, which we used over in the clean room with the spare OSEMs). We found a problem with the LR PRM OSEM reading on Dataviewer. It was saturating when the OSEM was just sitting on the table, with nothing between the LED and the sensor. We measured the output from the satellite box with the octopus cables, and measured 2.3 volts, which is too much for the DAQ. It seems fine when we install it in the cage, and the magnet is blocking part of the light. We should investigate the gain of the satellite box when convenient. This is not something that needs to be done prior to pump-down. Also, when we put an allen wrench to block the light while checking which OSEM was which, we noticed that the Dataviewer reading would go down to -2V, then come back to 0V when the light was completely blocked. This may be some incorrect compensation for some whitening. Again, we should look into this, but it is not terribly time-sensitive.

Once the OSEMs were centered, we tried to turn on the damping for the PRM. This was successful, so we are confident that we have put all of the OSEMs back in their correct places.

We found that we were easily able to get the PRM's oplev back on the QPD, so we ~centered the oplev, and then centered all of the PRM's OSEMs. This assumes that the oplev was in a good place, but I think we've determined that this is the case.

We did the same thing for the SRM and the BS, to check the OSEM values before we close up for good. We found that some of the SRM OSEMs were reading low (magnet too far in), and that all of the BS OSEMs were low, perhaps as if the table were tilted a tiny bit after removing and replacing the weight of the PRM. We recentered all of the OSEMs for both of these optics.

We checked that all of the pigtails for the PRM OSEMs were anchored to the PRM cage using some copper wire as tie-downs.

We checked that all of the earthquake stops were within 1mm or so of each of the 3 optics in the BS chamber. The SRM's earthquake stops were fairly far out. One of the bottom ones was far enough that when Yoichi turned it the wrong way (accidentally), it fell out. He put it back in, and adjusted all of the earthquake stops appropriately. This 1mm distance comes from Seji, and the specs for the optics' cages.

We did a look-through of the chamber, and took out all of the tools, and other things that were not bolted down to the table.

We have left the damping of the PRM off for the night.

To do: put the doors back on, and start the pump down.
  6629   Wed May 9 04:47:20 2012 JenneUpdateLockingPRM is really moving when PRMI locked

A few things tonight.  Locked both arms simultaneously (IR only).  Locked MICH, Locked PRMI, although it doesn't like staying locked for more than a minute or so, and not always that long.

Locking PRCL was possible by getting rid of the power normalization.  We need to get some triggering going on for the power norm.  I think it's a good idea for after the cavity is locked, but when PRCL is not locked, POP22 is ~0, so Refl33/Pop22 is ~inf.  The PRCL loop kept railing at the Limit that was set.  Getting rid of the power normalization fixed this railing. 

I took some spectra of PRM's oplev, while PRMI was locked, and unlocked.  The PRM is definitely moving more when the cavity is locked.  I'm not sure yet what to do about this, but the result was repeatable many times (~6 or 7 over an hour or so).  The OpLev spectra when PRMI was locked didn't depend too strongly on the PRM's alignment, although I think that's partly because I wasn't able to really get the PRM to optimal alignment.  I think POP22I is supposed to get to 7 or so...last week with Koji it was at least flashing that high.  But tonight I couldn't get POP22I above 4, and most of the time it wouldn't go above 3.  As I was aligning PRM and the circulating SB power increased, POP22I fluctuations increased significantly, then the cavity unlocked.  So maybe this is because as I get closer, PRM gets more wiggly.  I tried playing 'chicken' with it, and took spectra as I was aligning PRM (align, get some improvement, stop to take spectra, then align more, stop to take spectra....) but usually it would fall out of lock after 1-2 iterations of this incremental alignment and I'd have to start over.  When it relocked, it usually wouldn't come back to the same level of POP22I, which was kind of disappointing. 

In the PDF attached, pink and light blue are when the PRMI is locked, and red and dark blue are no PRCL feedback.  The effect is more pronounced with Pitch, but it's there for both Pitch and Yaw.

Also, I need to relook at my new restore/misalign scripts.  They were acting funny tonight, so I'm taking back my "they're awesome, use them without thinking about it" certification.

Attachment 1: PRM_louder_when_aligned.pdf
  6631   Wed May 9 09:19:22 2012 KojiUpdateLockingPRM is really moving when PRMI locked

Is this enhancement of spectrum caused by the lock? Or by the actuation?

If this is also seen with approximately same amount of actuation to PRM POS,
this is just a suspension problem.

If this is only seen with the PRM locked, this is somehow related to the opt-mechanical coupling.

  6781   Thu Jun 7 08:12:20 2012 steveUpdateSUSPRM is still oscillating



What not to do:

The PRM oplev servo was left on and it was driving this oscillation overnight.

 Oplev servo turned off and sus damping restored. What is kicking up the PRM?

 The PRM oscillation stopped by turnig off oplev servo.

Do not turn Oplev Servo on when PRM is missaligned !


Attachment 1: PRMoscil.png
  6785   Thu Jun 7 13:18:42 2012 ranaUpdateSUSPRM is still oscillating

  Set the PRM OL servo gains to zero until someone can take care of this. Turning off the buttons doesn't help anything if people run the alignment scripts.

ELOG V3.1.3-