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ID Date Author Type Category Subject
13936   Sun Jun 10 03:46:38 2018 KojiUpdateIOOWFS HEAD SW confusion

I was checking on the slow machine channels and found something I could not understand.

On the IOO WFS HEAD screen, there are two sets of 4 switches (magenta rectangles in Attachment 1) labeled 2/4/8/16dB.
But as far as I could confirm with the WFS demod (D980233) and WFS head (D980012) drawings, they are the gain (attenuation) switches for the individual segments.
Their epics variable names are "C1:IOO-WFS1_SEG1_ATTEN", "C1:IOO-WFS1_SEG2_ATTEN", etc...

I confirmed the switches are alive (effective), and they are not all ON or OFF. I wonder what is the real situation there...

13946   Mon Jun 11 22:46:24 2018 KojiUpdateIOOWFS HEAD SW confusion

The unfortunate discovery today was that the attenuator switches on the IMC WFS heads are actually assigned to individual segments, and they are active. That means that we have been running the WFS with an uneven gain setting. The attached PDFs show that the signals with the attenuators on and off all at the same time, while the WFS servo output was frozen. A more annoying feature is that when some of the attenuators are on, this does not lower the gain completely. I mean that the attenuated channels show some reduction of the gain, but that is not the level of reduction we see when all attenuators are turned on. This RF could come from some internal RF coupling or some similar effect.

Moreover, the demodulation phases are quite off for most of the segments.

So far, the WFS is running with this uneven attenuation. We take time to characterize the gain and retune the demod phases and input matrices.

Attachment 1: 180611_IMC_WFS1.pdf
Attachment 2: 180611_IMC_WFS2.pdf
13960   Thu Jun 14 00:46:09 2018 ranaUpdateIOOWFS HEAD SW confusion

its painful, but you and I should probably take these out, bypass the switches and use them with fixed gain; the 'Reed Relay' attenuators are not a good part for this app.

The historical problem is that they tend to self oscillate with full gain because they had 2 MAX4106 in series which couple to each other in the bad way --- need to remove one of them and set the gain of the other one to 10.

 Quote: The unfortunate discovery today was that the attenuator switches on the IMC WFS heads are actually assigned to individual segments, and they are active. That means that we have been running the WFS with an uneven gain setting.

5859   Wed Nov 9 21:48:43 2011 SureshUpdateIOOWFS Servo included into the MC_Autolocker

The WFS servo loop will come on 5 seconds after the MC is locked

I have uncommented the lines in the mcup script which turn on the WFS servos.  But I shifted their location to the part after the MC is locked.

3182   Thu Jul 8 19:43:16 2010 nancyUpdateIOOWFS calculations

The WFS error signals were recorded in the order

WFS1_PIT

WFS1_YAW

WFS2_PIT

WFS2_YAW

these measurements are made in the linear region, that is the MC is nearly perfectly aligned.

This is  the average and std. dev.of 5 measurements taken of the same signals over 10 secs each. The std. dev are under 10%. And hence, I will be using 10 secs for measurements for the WFS signals after perturbations to the mirrors.

avg =

829.4408
-517.1884
297.4168
-944.7892

std_dev =

9.0506
22.9317
15.4580
8.9827

I perturbed the Pitch and Yaw of the Three mirrors (in order MC1,2,3), using ezcastep and calculated the coefficients that relate these perturbations to the WFS error signals.

The perturbation made is of -0.01 in each dof , and after measuring the WFS error for it, the system is reverted back to the previous point before making the other perturbation.

I was able to calculate the coefficients since I have assumed a linear relationship..

Following are the coefficients calculated using 10 secs measurements

coef_mat =

1.0e+05 *

MC1_P   MC1_Y  MC2_P   MC2_Y    MC3_P   MC3_Y  constant
WFS1_PIT        -0.1262    0.3677   -0.4539   -0.6297   -0.1889   -0.1356   0.013664
WFS1_YAW     -0.0112   -0.7415   -0.1844    2.4509   -0.0023   -0.3531  -0.016199
WFS2_PIT         0.1251    0.4824   -0.2028   -0.6188    0.0099   -0.1490   0.006890
WFS2_YAW      0.0120   -0.7957   -0.1793    0.9962   -0.0493    0.2672 -0.013695

Also, I measured the same thing for 100s, and to my surprize, even the signs of coeficients are different.

coef_mat =

1.0e+05 *

MC1_P   MC1_Y  MC2_P   MC2_Y    MC3_P   MC3_Y   constant
WFS1_PIT       -0.1981    0.3065   -0.6084   -0.9349   -0.4002   -0.3538   0.009796
WFS1_YAW     0.0607   -0.6977    0.0592    2.8753    0.3507    0.0373   -0.008194
WFS2_PIT        0.0690    0.4769   -0.2859   -0.7821   -0.1115   -0.2953  0.004150
WFS2_YAW     0.0580   -0.8153   -0.0937    1.1424    0.0650    0.4203  -0.010629

The reason I can understand is that the measurements were not made at the same time, and hence conditions might have changed.

A thing to note in all these coefficients is that they relate the error signals to the 'perturbation' around a certain point (given below). That point is assumed to lie in the linear region.

MC1_PIT      2.6129
MC1_YAW   -5.1781
MC2_PIT       3.6383
MC2_YAW    -1.2872
MC3_PIT      -1.9393
MC3_YAW    -7.518

3184   Thu Jul 8 21:44:43 2010 nancyUpdateIOOWFS calculations

I just found the singular values and the condition number of the 4*4 matrix relating the WFS error signals and the MC1 and MC2 movements.

### the condition number is ~12.5. I think its small enough to continue with the scheme. (if the measurements and all are reliable).

7444   Wed Sep 26 23:55:14 2012 JenneUpdateIOOWFS centered

Since the MC spots are good, I put the beam back on WFS 1 and WFS 2.

Also, I changed the indicators on the LockMC screen to reflect the change in elog 7289, where we added another on/off switch for the WFS so that the ASS could be on, but the WFS off.  For the last month, the WFS could be disabled, but the MC screen's indicators would suggest that we were pushing very significantly on all 3 MC mirrors.  Now the MC screen reflects reality a little better.

I also uncommented the WFS lines in the mcup script.  Den had commented them out, but didn't elog about it!  C'mon Den, please elog stuff!!!!  (He confessed out loud the other day, but it still wasn't in the elog).

I'm leaving the WFS loops disabled (even though the MC autolocker tries to turn them on, I have them manually disabled using the extra on/off switch) since they're unstable.  I'm in the process of figuring out what's wrong.  So far, the WFS improve the MC alignment for a minute or two, and then they totally misalign the MC.  This is a work in progress.

1358   Thu Mar 5 00:06:32 2009 Kakeru, RanaUpdateIOOWFS centering
We found that the MC REFL image was no longer round and that the MCWFS DC quadrant spots were mostly
in one quadrant. So we re-centered the MCWFS beams in the following way:

1) We unlocked the MZ and adjusted the PZT voltage to keep the beam on the WFS from saturating.
2) Re-aligned the black hole beam dump to center its beam in its aperture.
3) centered the beam on the MCWFS optics and MCWFS QPD displays.
4) Relocked MC.

Below is the image of the IOO Strip tool. You can see that the MC REFL DC is now more flat. The
MC pointing has also been changed (see the MC TRANS HOR & VERT channels). The MC transmitted
light is also now more stable and higher.

We tried to center the QPD, and we found that there were a few hundred mV of dark offset for each
/cvs/cds/caltech/scripts/MC/WFS/McWFS_dc_offsets
Attachment 1: IOO_graph.jpg
1391   Wed Mar 11 23:41:33 2009 Kakeru, YoichiUpdateIOOWFS centering

We found the MC reflection was distorted . And WFC beam went to upward of QPD

We recentered WFC beam and these problems were fixed

15450   Sun Jul 5 18:25:42 2020 ranaUpdateElectronicsWFS characterization

in the lab, checkin on the WFS

Sun Jul 5 18:25:50 2020

I redid Gautam's measurements to get a baseline before changing the head, and my results are very different: To me it looks like the WFS2 quadrants are all OK.

Measurement Details:

1. The whole AG4395 + breadboard Jenne laser is wheeled over next to the SW side of the AP table.
2. The output of the 1611 goes into channel R of the 4395
3. I disconnected all the LEMO cables from the head and then plugged a LEMO-BNC cable into the plugs one at a time. The existing LEMO connectors, which take the signals back to the demode board, were all a little loose, so I adjusted them with some pliers (see video).
4. The Atten = 0 dB for all AG4395 channels
5. Source drive = 0 dBm. Checked with a -10 dBm drive that there was no change in the observed TFs, so I guess a 0 dBm drive doesn't make things nonlinear.
6. When I first turned the setup on, the Yellow 'limit' light was ON on the ILX laser current driver, so maybe the modulation wasn't getting to the laser diode as we wish.
7. did not change any WFS MEDM settings for these measurements. Not sure if any of those buttons work anyway.

I've left the setup as is in case either me or Gautam want to double check. If we're agreed on this response, I'll remove the notches and disable the RF attenuators.

Sun Jul 5 21:42:45 2020

Attachment 1: WFS_attenOff.pdf
15547   Sat Aug 29 20:07:48 2020 ranaUpdateElectronicsWFS characterization

I set up to do the WFS head modifications today, but I was shot down in flames due to a missing AC/DC adapter.

The Prologix GPIB-ethernet dongle needs +8-13 V to run. Some riff raff has removed the adapter and I was thunderstruck to see that it had not been returned.

I did the usual hunt around the lab looking for something with the right specs and connector. I found one that could do +9V and had the right connector, but it didn't light up the adapter so I put it back in black SP table.

I'll order a couple of these (5 ordered for delivery on Wednesday) in case there's a hot demand for the jack / plug combo that this one has. The setup is in the walkway, but I returned the AS table to the usual state and made sure the IMC is locking well.

15548   Sat Aug 29 22:10:09 2020 gautamUpdateElectronicsWFS characterization

Clearly this "riff raff" is referring to me. It won't help today I guess but there is one each on the carts holding the SR785 (currently both in the office/electronics bench area), and the only other unit available in the lab is connected to a Prologix box on the Marconi inside the PSL enclosure.

 Quote: The Prologix GPIB-ethernet dongle needs +8-13 V to run. Some riff raff has removed the adapter and I was thunderstruck to see that it had not been returned.
15472   Sun Jul 12 22:40:35 2020 gautamUpdateElectronicsWFS characterization - old SURF report

After some hunting, I found this old SURF report with the WFS head measurements. The y-axes don't make much sense to me, and I can't find the actual data anywhere (her wiki page doesn't actually exist). So I think it's still unknown if these heads ever had the advertised transimpedance gain, or if the measured transimpedance of ~1kohm was what it always was.

8724   Wed Jun 19 15:07:20 2013 ranaUpdateIOOWFS debugging

Trying to figure out what's wrong with the MC WFS:

1) The symptom seems to be that the control signals become very large in the pitch and then the loop breaks when they saturate. Usually this is due to a degenerate matrix or improper inversion. Most likely some of the BURT restore is bad or the analog gain for one of the WFS has been switched when Jamie was doing the "Guardian" debugging.

2) In checking this out, I found that several buttons on the WFS  screens were not working (and apparently have never been working). Please try to test things in the future...The filter bank buttons in C1IOO_MC_TRANS_QPD were using relative path names; fixed these to use abs path names. The buttons in the WFS_MASTER for the IOO_PIT banks were using IOO_PITCH instead...

2.5) Recentered beams on WFS heads with MC alignment good and MC unlocked.

3) Main problem in the WFS still not found - disabling this in the autolocker.

8733   Thu Jun 20 15:15:39 2013 ranaUpdateIOOWFS debugging

Tried a bunch of stuff, but eventually just turned off the TRANS_QPD loops and loops are stable. Needs more debugging.

1. Modified the on/off scripts so that the Integrators are no longer toggled. No reason to turn them off since we are clearing the filter bank histories.
2. With QPD feedback OFF, I have lowered the overall gain by 15x so that its just drift control.
3. Deleted unused / bad filters from the main filter banks.
4. Gautam is going to debug the QPD with a red laser pointer and then elog.
5. Jamie is checking out the MC Coil dewhitening logic to see if that's in a funny state.
Attachment 1: Untitled.png
8815   Tue Jul 9 20:09:53 2013 KojiUpdateIOOWFS debugging

The low UGFs of the MC WFS servos made the MC insane thesedays:
The servos are too slow and we kept having significant misalignment left uncompensated.

I increased the total gain of the MC WFS from 0.01 to 0.4 (x40) to make the UGFs of the
WFS paths to ~2Hz. This was too much gain for the QPD path so the gains for the QPD paths
were reduced by a factor of 4 (x10 in total).

The script mcwfsup was also modified accordingly.

9210   Sun Oct 6 23:43:07 2013 ranaUpdateIOOWFS debugging

 Quote: Tried a bunch of stuff, but eventually just turned off the TRANS_QPD loops and loops are stable. Needs more debugging. Modified the on/off scripts so that the Integrators are no longer toggled. No reason to turn them off since we are clearing the filter bank histories. With QPD feedback OFF, I have lowered the overall gain by 15x so that its just drift control. Deleted unused / bad filters from the main filter banks. Gautam is going to debug the QPD with a red laser pointer and then elog. Jamie is checking out the MC Coil dewhitening logic to see if that's in a funny state.

Back around June 18, Jamie was debugging some Guardian code here to replace our MC autolocker. Afterwards our MC WFS stopped working. We never figured out what went wrong, but at the time we turned off the feedback from the MC trans QPD and it stabilized the response at DC.

Today, I noticed that the trans QPD feedback is on.  Did anyone do this on purpose?

Its problem causing behavior is slow, but you can catch it if you wait. With the nominal WFS gain of 0.4 the control signal ramps up monotonically at a rate of ~100 counts/minute. Depending upon the static alignment of the MC, this could let it take 10 minutes or a few hours before it rails the MC SUS actuators and breaks the lock. Very sneaky. Don't turn this loop back on without making sure its working and not breaking. I would trend it for you, but the SLOW channels associated with the TRANS QPD servo are not trended --- does anyone know how to get them in the channel list?

8735   Thu Jun 20 20:46:16 2013 gautamUpdateIOOWFS debugging-QPD debugging

I wanted to make sure that the QPD map on the C1IOO_MC_TRANS_QPD.adl screen corresponded to the actual physical quadrants on the photodiode at the MC2 table. We turned MC_WFS_OUT  OFF before fiddling around with a red laser pointer to try and map the quadrants.

I initially verified the correspondence between the various quadrants and the text-fields displaying the outputs using PV_Info. I found that there was good agreement in this respect. So for instance, field adjacent to the quadrant marked "1" on the C1IOO_MC_TRANS_QPD.adl screen had the following input channel: IOO_MC_TRANS_SEG1_INMON. The filter banks were empty and there was just an overall gain on -1 on all four channels. The channels leading to the filter-banks were the 'right' ones: quadrant 1 for the top bank, then quadrants 2,3 and 4 down.

Next, a red laser pointer was used to map the quadrants. Here, there was some disagreement between the physical quadrants and the map on the C1IOO_MC_TRANS_QPD.adl screen, which is summarised in the attached image-the whole thing is sort of rotated 180degrees about the centre.

The interpretation of the figure is as follows:

MC_WFS_OUT was turned back ON.

6660   Tue May 22 13:06:11 2012 JenneUpdateIOOWFS didn't turn off automatically

I just sat down in the control room, and discovered the PMC (and everything else) unlocked.  I relocked the PMC, but the MC wasn't coming back.  After a moment of looking around, I discovered that the WFS were on, and railing.  I ran the "turn WFS off" script, and the MC came back right away, and the WFS came on as they should.

We need to relook at the WFS script, or the MC down script, to make sure that any time the MC is unlocked, no matter why it unlocked, the WFS output is off and the filter histories are cleared.

6669   Wed May 23 21:32:15 2012 SureshUpdateIOOWFS didn't turn off automatically

 Quote: I just sat down in the control room, and discovered the PMC (and everything else) unlocked.  I relocked the PMC, but the MC wasn't coming back.  After a moment of looking around, I discovered that the WFS were on, and railing.  I ran the "turn WFS off" script, and the MC came back right away, and the WFS came on as they should. We need to relook at the WFS script, or the MC down script, to make sure that any time the MC is unlocked, no matter why it unlocked, the WFS output is off and the filter histories are cleared.

The only script that can currently take this action is the MC autolocker.  If that is disabled first and the PMC unlocks later, the WFS will not be turned off.  During the last round of discussions we had about the autolocker script, sometime last Nov, we decided that too much automation is not desirable and that the autolocker should be kept as simple as possible.

5688   Tue Oct 18 21:19:18 2011 ranaConfigurationIOOWFS disabled in SUS

I found that the MC WFS had large offset control signals going to the MC SUS. Even though the input switch was off, the integrators were holding the offset.

I have disabled the ASCPIT outputs in the MC SUS. Suresh is going to fix the MC autolocker script to gracefully handle the OFF and ON and then test the script before resuming the WFS testing.

MCL data for OAF may be suspect from this morning.

14858   Thu Sep 5 18:42:19 2019 aaronHowToCDSWFS discussion, restarting CDS

[aaron, rana]

While going to take some transfer functions of the MC WFS loop, LSC was down. When we tried to restart the FE using 'rtcds restart --all', c1lsc crashed and froze. We manually reset c1lsc, then laboriously determined the correct order of machines to reboot. Here's what works best:

on c1lsc:

rtcds start c1x04 c1lsc c1ass c1oaf c1cal c1daf

Starting c1dnn crashes the other FE

on c1ioo

rtcds restart --all

on c1sus

rtcds restart c1rfm c1sus c1mcs

restarting c1pem crashes the other FE on c1sus

We're seeing a lot of red IPC indicators--perhaps it's an issue with the order we're restarting?

14859   Thu Sep 5 20:30:43 2019 ranaHowToCDSWFS discussion, restarting CDS

via Polish chat, GV tells us to RTFE

14860   Fri Sep 6 09:40:56 2019 aaronHowToCDSWFS discussion, restarting CDS

As suggested, I ran the script cds/rebootC1LSC.sh

I got a timeout error when the script tried closing the PSL shutter ('C1:AUX-PSL_ShutterRqst' not found), but Rana and I closed the shutter before leaving last night. c1sus is down, so the script found no route to host c1sus; I'm thinking I need to reset c1sus for the script to run completely. Nonetheless, c1lsc was rebooted, which crashed c1ioo and left the c1lsc FE all red (probably because c1sus wasn't restarted).

14861   Fri Sep 6 11:56:44 2019 aaronHowToCDSWFS discussion, restarting CDS

## Rebooting

I reset c1lsc, c1sus, and c1ioo.

I noticed that the script gives the command 'ssh c1XXX', but we have been getting no route to host using this command. Instead, the machines are currently only reachable as c1XXX.martian. I'm not sure why this is, so I just appended .martian in rebootC1LSC.sh

This time, the script does run. I did get 'no route to host' on c1ioo, so I think I need to reset that machine again. After reset, the script failed to login to c1ioo and c1lsc.

Fri Sep 6 13:09:05 2019

After lunch, I reset the computers again, and try the script again. There is again no route to host for c1ioo. I'm going inside to shutoff the power to c1ioo, since the reset buttom seems to not be working. I still can't login from nodus, so I'm bringing a keyboard and monitor over to plug in directly.

On reset, c1ioo repeatedly reaches the screen in attachment 1, before going black. Holding down shift or ctrl+alt+f1 doesn't get me a command prompt. After waiting/searching the elog for >>3 min, we decided to follow these instructions to cycle the power of c1ioo. The same problem recurred following power up. I found online some instructions that the SunSystems 4600 can hang during reboot if it has become too hot ("reboot during a thermal shutdown"); I did notice that the temperature light was on earlier in this procedure, so perhaps that is the problem. I followed the wiki instructions to shut down the computer again (pressed power button, unplugged 4 power supplies from back of machine), and left it unplugged for 10-30 min (Fri Sep 6 14:46:18 2019 ).

Fri Sep 6 15:03:31 2019

Rana plugged in the power supplies and reset the machine again.

Fri Sep 6 16:30:37 2019

c1ioo is still unreachable! I pressed reset once, and the reset button flashes white. The yellow warning light is still on.

Fri Sep 6 16:54:21 2019

The reset light has stopped flashing, but I still can't access c1ioo. I reset once more, this time watching c1ioo on a monitor directly. I'm still seeing the same boot screen repeatedly. I do see that CPU0 is not clocking, which seems weird.

## Troubleshooting CPU module

Following gautam's elog here, I found the Sun Fire X4600 manual for locating faulty CPUs. After the white reset light stopped flashing, I held down the power button to turn off the system. Before shutdown, all of the CPU displayed amber lights; after shutdown, only the leftmost CPU (as viewed from the back, presumably CPU0) displays an amber light. The manual says this is evidence that the CPU or DIMM is faulty. Following the manual, I remove the standby power, then checked out these Instructions for replacing the CPU to remove the CPU; Gautam also has done this before.

Fri Sep 6 20:09:01 2019 Fri Sep 6 20:09:02 2019

I pulled the leftmost CPU module out, following the instructions above. The CPU module matches the physical layout and part number of the Sun Fire X4600 M2 8-DIMM CPU module; pressing the fault reminder light gives amber indicators at the DIMM ejectors, indicating faulty DIMMs (see). The other indicator LEDs did not illuminate.

I located several spare DIMMs in the digital cabinet along Y arm (and a couple with misc computer components in the control room), but didn't find the correct one for this CPU module. The DIMM is Sun PN 371-1764-01; I found it online and ordered eight. Please let me know if this is incorrect.

To protect the CPU module, I've put it in an ESD safe bag with some bubble wrap and a note. It's on the E shop bench.

## Conclusion: Need new DIMM, didn't find the correct part but ordered it.

Attachment 1: B26CECF8-FC0D-4348-80DC-574B1E3A4514.jpeg
14862   Fri Sep 6 15:12:49 2019 KojiHowToCDSWFS discussion, restarting CDS

Assuming you are at pianosa, /etc/resolv.conf is like

# Generated by NetworkManager nameserver 192.168.113.104 nameserver 8.8.8.8

But this should be like

nameserver 192.168.113.104
nameserver 131.215.125.1
nameserver 8.8.8.8

search martian

as indicated in https://nodus.ligo.caltech.edu:8081/40m/14767

I did this change for now. But this might get overridden by Network Manager.

6992   Thu Jul 19 02:32:45 2012 JenneUpdateIOOWFS don't come on automatically??

The MC unlocked ~20 min ago, correlated with 2 consecutive earthquakes in Mexico.  The MC came back fine after a few minutes, but the WFS never engaged.  I turned them on by hand.  I think that Yuta mentioned once that he also had to turn the WFS on by hand.  There may be a problem in the unlock/relock catching that needs to be looked at, to make sure the WFS come back on automatically.

Also, someone (Masha and I) should look at the seismic BLRMS.  I have suspected for a few days that they're not telling us everything that we want to know.  Usually, if there's an earthquake close enough / big enough that it pops the MC out of lock, it is clear from the BLRMS that that's what happened, but right now it doesn't look like much of anything....just kind of flat for hours.

12897   Tue Mar 21 21:21:58 2017 gautamUpdateIOOWFS filter banks updated

The arrangement of filters in the WFS loop filter banks have been altered, Rana will update with details of the motivation behind these changes. Here is how the screen looks now:

I have updated the C1IOO SDF table, and also the mcwfson script to reflect these changes. The latter has been svn committed.

15741   Sat Dec 19 20:24:25 2020 gautamUpdateElectronicsWFS hardware install

I installed 4 chassis in the rack 1X2 (characterization on the E-bench was deemed satisfactory, I will upload the analysis later). I ran out of hardware to make power cables so only 2 of them are powered right now (1 32ch AA chassis and 1 WFS head interface). The current limit on the +24V Sorensens was raised to allow for similar margin to the limit with the increased current draw.

Remaining work:

1. Make 2 more power cables for ISC whitening chassis and quad demod chassis.
2. Make a 2x 4pin LEMO-->DB9 cable to digitize the FSS and PMC diagnostic channels with the new AA chassis. If RnD cables has a very short turnaround time, might be worth it to give this to them as well.
3. Connect ADC1 on c1ioo machine to new AA chassis (transfer SCSI cable from existing AA unit to the new one). This will necessarily involve some model changes as well.
4. Make a short cable to connect 55 MHz output from RFsource box to the LO input on the quad demod chassis.
5. Install the WFS head on the AS table at a suitable location. Probably will need a focusing lens as well.
6. Connect WFS head to the signal processing electronics (the cables were already laid out by Jordan and I).
7. Make the necessary CDS model changes (WFS filters, matrices, servos etc). I personally don't see the need for a new model but if anyone feels strongly about separating the IMC WFS and AS WFS we can set up another model.
8. Commission the system.

While I definitely bumped various cables, I don't seem to have done any lasting damage to the CDS system (the RFM errors remain of course).

14945   Mon Oct 7 14:51:20 2019 aaronUpdateElectronicsWFS head RF measurements

Mon Oct 7 14:51:53 2019. I closed the PSL shutter to measure the WFS head responsivity.

I made a thru calibration as in this elog, treating laser, reference PD, and WFS RF output as a three-port device. The DC current supplied to the laser is 20.0 mA in all cases. The Agilent spectrum analyzer supplies a -10 dBm excitation to Jenne laser's AM port, and A/B is measured with 20dB attenuation on each input port. Results are in /users/aaron/WFS/data/191007/. The calibration had 100 averages, all other measurements 32 averages; other parameters found in the yml file, same folder as the data.

 Measurement Reference PD DC (V) WFS Segment DC (V) WFS Segment DC, beam blocked (V) File Notes WFS 1 Segment 1 1.86 0.79 -0.23 TFAG4395A_07-10-2019_154446.txt WFS 1 Segment 2 1.86 0.72 -0.30 TFAG4395A_07-10-2019_155017.txt WFS 1 Segment 3 1.86 0.79 -0.21 TFAG4395A_07-10-2019_155645.txt WFS 1 Segment 4 1.86 0.70 -0.30 TFAG4395A_07-10-2019_160334.txt TFAG4395A_07-10-2019_160847.txt I noticed the BS-PRM illuminator was on, and turned it off for the second measurement WFS 2 Segment 1 1.86 0.56 -0.38 TFAG4395A_07-10-2019_162533.txt WFS 2 Segment 2 1.86 0.71 -0.21 TFAG4395A_07-10-2019_163402.txt WFS 2 Segment 3 1.86 0.68 -0.28 TFAG4395A_07-10-2019_164152.txt WFS 2 Segment 4 1.86 0.57 -0.42 TFAG4395A_07-10-2019_164745.txt

I normalized the result by the difference between the dark and bright DC levels of each segment.

Mon Oct 7 17:29:58 2019 opened PSL shutter.

14951   Tue Oct 8 16:00:06 2019 aaronUpdateElectronicsWFS head RF measurements

I simulated this circuit with zero, but haven't gotten the results to match the measurements above.

Removing the DC readout chain from the circuit does not affect the AC response.
Perhaps something to do with the (currently unmodeled) capacitance of the diode? I think this forms a necessary part of the resonant circuit. The gain is also suspiciously low.
Edit: Indeed, simply adding the 'typical' shunt capacitance (9pF) and a small series resistor (10 Ohm) gives the right qualitative response
The python notebook is in /users/aaron/WFS/electronics.
The DC response flattens off at ~20dB by ~mHz, which also seems longer than the timescales I saw while measuring; I'm not sure I have some of the AD827 parameters correct (eg 'delay')

I came across this nice note on photodiodes.

Attachment 1: WFS_ACresponse.pdf
Attachment 2: WFS_DCresponse.pdf
14959   Wed Oct 9 12:15:05 2019 ranaUpdateElectronicsWFS head RF measurements

It would be good if you and Shruti can look at how to change the parameters in Zero so as to do a fit to the measured data. Usually, in scipy.optimize we give it a function with some changeable params, so maybe there's a way to pass params to a zero object in that way. I think Ian and Anchal are doing something similar to their FSS Pockel's cell simulator.

15731   Thu Dec 10 22:46:57 2020 gautamUpdateASCWFS head assembled

The assembly of the head is nearly complete, I thought I'd do some characterization before packaging everything up too nicely. I noticed that the tapped holes in the base are odd-sized. According to the official aLIGO drawing, these are supposed to be 4-40 tapped, but I find that something in between 2-56 and 4-40 is required - so it's a metric hole? Maybe we used some other DCC document to manufacture these parts - does anyone know the exact drawings used? In the meantime, the circuit is placed inside the enclosure with the back panel left open to allow some tuning of the trim caps. The front panel piece for mounting the SMA feedthroughs hasn't been delivered yet so hardware-wise, that's the last missing piece (apart from the aforementioned screws).

Attachment #1 - the circuit as stuffed for the RF frequencies of relevance to the 40m.

Attachment #2 - measured TF from the "Test Input" to Quadrant #1 "RF Hi" output.

• There is reasonable agreement, but not sure what to make of the gain mismatch at most frequencies.
• The photodiode itself hasn't been installed yet, so there will be some additional tuning required to account for the interaction with the photodiode's junction capacitance.
• I noticed that the Qs of the resonances in between the notches is pretty high in this config, but the SPICE model also predicts this, so I'm hopeful that they will be tamed once the photodiode is installed.
• One thing that is worrying is the feature at ~170 MHz. Could be some oscillation of the LM opamp. All the aLIGO WFS test procedure documentation shows measurements only out to 100 MHz. Should we consider increasing the gain of the preamp from x10 to x20 by swapping the feedback resistor from 453 ohms to 1 kohm? Is this a known issue at the sites

Update 11 Dec: For whatever reason, whoever made this box decided to tap 4-40 holes from the bottom (i.e. on the side of the base plate), and didn't thread the holes all the way through, which is why I was unable to get a 4-40 screw in there. To be fair the drawing doesn't specify the depth of the 4-40 holes to be tapped. All the taps we have in the lab have a maximum thread length of 9/16" whereas we need something with at least 0.8" thread length. I'll ask Joe Benson at the physics workshop if he has something I can use, and if not, I'll just drill a counterbore on the bottom side and use the taps we have to go all the way through and hopefully that does the job.

The front panel I designed for the SMA feedthroughs arrived today. Unfortunately, it is impossible for the D-sub shaped holes in this box to accommodate 8 insulated SMA feedthroughs (2 per quadrant for RF low and RF high) - while the actual SMA connector doesn't occupy so much space, the plastic mold around the connector and the nut to hold it are much too bulky. For the AS WFS application, we will only need 4 so that will work, but if someone wants all 8 outputs (plus an optional 9th for the "Test Input"), a custom molded feedthrough will have to be designed.

As for the 170 MHz feature - my open loop modeling in Spice doesn't suggest a lack of phase margin at that frequency so I'm not sure what the cause is there. If this is true, just increasing the gain won't solve the issue (since there is no instability at least by the phase margin metric). Could be a problem with the "Test Input" path I guess. I confirmed it is present in all 4 quadrants.

Attachment 1: aLIGO_wfs_v5_40m.pdf
Attachment 2: TF_meas.pdf
15736   Thu Dec 17 15:23:56 2020 gautamUpdateASCWFS head characterization

Summary:

I think the WFS head performs satisfactorily.

• The (input-referred) dark noise level at the operating frequency of 55 MHz is ~40pA/rtHz (modelled) and ~60 pA/rtHz (measured, converted to input-referred). See Attachment #1. Attachment #5 has the input referred current noise spectral densities, and a few representative shot noise levels.
• The RF transimpedance gain at the operating frequency is ~500 ohms when driving a 50 ohm load (in good agreement with LTspice model). See Attachment #2 and Attachment #3.
• The resonant gain to notch ratios are all > 30 dB, which is in line with numbers I can find for the WFS installed at the sites (and in good agreement with the LTspice model as well).
• There are a few lines visible in the noise measurement. But these are small enough not to be a show-stopper I think.

Details and remarks:

1. Attachment #4 shows a photo of the setup.
• The QPD used was S/N #84.
• The heat sinks have a bunch of washers because the screw holes were not tappe at time of manufacture.
• There isn't space to have 8 SMA feedthroughs in the D-shaped cutouts, so we can only have the 4 "RF HI" outputs without some major metalwork.
• C9 has been remvoed in all channels (to isolate the "TEST INPUT").
2. I found that some quadrants displayed a ~35 MHz sine-wave of a few mV pk-pk when I had the back of the enclosure off (for tuning the notches). The hypothesis is that this was due to some kind of stray capacitance effect. Anyways, once I closed everything up, for the noise measurement, this peak was no longer visible. With an HP8447A preamp, I measured an RMS voltage of ~2mV rms on an oscilloscope. After undoing the 20 dB gain of the amplifier, each quadrant has an output voltage noise of ~200 uVrms (as returned by the "measure" utility on the scope, I don't know the specifics of how it computes this). Point is, there wasn't any clear sine-wave oscillations like I saw on two channels when the lid was off.
3. Some of the lines are present during some measurement times but not others (e.g. Q4 blue vs red curve in Attachment #1). I was doing this work in the elec-bench area of the lab, right next to the network switches etc so not exactly the quietest environment. But anyway, I don't see anything in these measurements that suggest something is seriously wrong.
4. In the transfer function measurements, above 150 MHz, there are all sorts of features. But I think this is a measurement artefact (stray cable capacitance etc) and not anything real in the RF signal path. Koji saw similar effects I believe, and I didn't delve further into it.
5. The dark noise of the circuit is such that to be shot noise limited, each quadrant needs 10 mA of DC photocurrent. The light bulb we have has a max current rating of 0.25A, with which I could only get 3 mA DC per quadrant. So the 55 MHz sideband power needed to be shot noise limited is ~50 mW - we will never have such high power. But I think to have better performance will need a major re-work of the circuit design (finite Qs of inductors, capacitors etc).
6. Regarding the transimpedance gains - in my earlier plots, I omitted the 50ohm input impedance of the AG4395A network analyzer. The numbers I report here are ~half of those earlier in this thread for this reason. In any case, I think this number is what is important, since the ADT-1-1 on the demod board RF input has an input impedance of 50ohm.
7. Regarding grounding - the RF ground on the head is actually isolated from the case pretty well. Two locations of concern are (i) the heat sinks for the voltage regulator ICs and (ii) the DB15 connector shield. I've placed electrically insulating (but thermally conducting) pads from TO220 mounting kits between both sets of objects and the case. However, for the Dsub connector, the shape of the pad doesn't quite fit all the way round the connector. So if I over-tighten the 4-40 mounting bolts, at some point, the case gets shorted to the RF ground, presumably because the connector deforms slightly and touches the case in a spot where I don't have the isolating pad installed. I think I've realized a tightness that is mechanically satisfying but electrically isolating.
8. I will do the fitting at my leisure but the eye-fit is already suggesting that things are okay I think.

If the RF experts see some red flags / think there are more tests that need to be performed, please let me know. Big thanks to Chub for patiently supporting this build effort, I'm pleasantly surprised it worked.

Attachment 1: oNoise.pdf
Attachment 2: Z_Hi.pdf
Attachment 3: Z_Low.pdf
Attachment 4: IMG_9030.jpg
Attachment 5: iNoise.pdf
16943   Fri Jun 24 12:13:16 2022 JCUpdateIOOWFS issues

[Yuta, JC]

It seems that early this morning MC got very misaligned. Yuta was able to align the Mode Cleaner again by individually adjusting the MC1 MC2, and MC3. Once transmission reach ~12000, we went ahead and turned on WFS. Oddly enough, the transmission began plummeting and MC fell out of lock. After this, Yuta reset the WFS offsets and realigned the WFS QPDs. We then locked MC and turned on WFS once again, but the same issue happened. After fiddeling around with this, we found the if we set C1:IOO-MC2_TRANS_PIT_OUTPUT and C1:IOO-WFS1_YAW_OUTPUT equal to 0, WFS does not cause this issue. Is there a proper to reset WFS, aside from only zeroing the offsets?

Attachment 1: WFS.png
16946   Sat Jun 25 14:29:48 2022 AnchalUpdateIOOWFS issues

This issue is very weird and still unresolved. Without WFS loops, we'll have to realign IMC often and we might loose IMC alignment completely during weekends or long weekends.

I tried following things today but nothign worked:

• Blocked WFS PDs and reset DC offsets (sitemap>C1IOO>C1IOO_WFS_MASTER>! Actions>Correct WFS DC Offsets).
• Switched off MC chamber lights.
I felt that they might be on, but later I feel that wasn't the case. Anyways, this didn't help.
• Algined IMC manually using cavAlign tool with MC2-MC3 and then tweaking MC1 and MC3 a little bit. Reach 13.6k in C1:IOO-MC_TRANS_SUM. Then I unlocked IMC with autolocker off, centered beam on WFSs (they were pretty off even though we have been centering them this week), and then reset RF offsets (sitemap>C1IOO>C1IOO_WFS_MASTER>! Actions>Correct WFS DC Offsets). This did not help either.
• The fact that IMC started misbehaving since Thursday onwards was bugging me that maybe the FE models did not come online properly, that maybe some RTS link is broken in IOO model which is causing the feedback loop to not work. So I went ahead and restarted all models, that didn't help either.
• Now we have a restartAllModels.sh script which restarts all cds system and restores state to just before restarting. It also makes sure that watchdogs are engaged safely particularly for new suspesnions where alignment offsets are ramped.

We need to investigate this as first priority. Maybe some cable is loose, some PD power supply not working etc. Until we fix this, people should align IMC to > 12000 transmission counts whenever they have a spare 5 min. We need to work in place of WFS for sometime.

16947   Sat Jun 25 20:23:59 2022 KojiUpdateIOOWFS issues

I could run the WFS servo (6dofs) for more than 15min by flipping the sign for the MC2 Pit and WFS1 Yaw. (See attachments)

This may mean that the sign of the loops / the input matrix / the output matrix, as well as the sensors and actuators, have the problem.
Isn't it the time to measure the sensing/actuation matrices? Maybe Tomislav already has the data?

I have reverted the changes as you may need more careful investigation.

Attachment 1: Screen_Shot_2022-06-25_at_20.23.21.png
Attachment 2: Screen_Shot_2022-06-25_at_20.29.24.png
16949   Mon Jun 27 12:32:45 2022 yutaUpdateIOOWFS issues fixed

[Anchal, Yuta]

We found that MC1 local damping loop signs were revereted to the state before our standardization on June 7th (40m/16898), but the WFS output matrix was not reverted.
This caused the sign flip in the feedback to MC1, which caused the IMC WFS issue.
This probably happened when we were restarting the models after RTS modeling (40m/16935). We might have used wrong snap files for burt-restoring.

We went back to the snapshot taken at 09:19 June 21, 2022 and now the IMC WFS is working,

16835   Fri May 6 13:48:34 2022 AnchalUpdateBHDWFS loop instability fixed

[Yuta, Anchal]

We investigated why WFS loop wasn't working. It seemed like WFS1 PIT error signal has a huge offset which would push the loop to misalign all optics' PIT. So we did the following steps:

• Cover the WFS with Aluminium foils. Run Sitemap>IOO>C1_IOO_WFS_MASTER>!Actions>Correct WFS DC offsets.
• Then center the WFS beams on the QPDS while looking at C1:IOO-WFS1/2_PIT/YAW_DC channels.
• Then Switch off WFS loop, Switch off Autolocker, toggler the PSL Shutter so that IMC unlocks and does not catch lock back, and tehn run Sitemap>IOO>C1_IOO_WFS_MASTER>!Actions>Correct WFS RF offsets.
• The above script found significant changes required in WFS1 RF offsets. After this, we opened the shutter and WFS loops were working fine.
14876   Fri Sep 13 10:53:40 2019 aaronUpdateIOOWFS loop measurements

I'm scripting the WFS sensing matrix measurements. I haven't really scripted DTT before, so I'm trying to find documentation or existing scripts. I came across this elog where Gautam measured a sensing matrix during DRMI lock, and he pointed me to some .xml files used for these measurments.

14878   Mon Sep 16 05:08:04 2019 ranaUpdateIOOWFS loop measurements

not need to use DTT. I'm attaching some half-finished notebooks that give the gist.

2. Downsample the data for ease of use.
4. demodulate the data at the specified frequencies.

That's it! Now you have the complex, single frequency TFs. Next you invert the matrix.

Attachment 1: LSCsensingMatrix.ipynb
{
"cells": [
{
"cell_type": "markdown",
"source": [
"# Get some ASC data - Calculate Sensing Matrix \n",
"### also make the radar plots"
]
},

... 327 more lines ...
Attachment 2: ASCsensingMatrix.ipynb
{
"cells": [
{
"cell_type": "markdown",
"source": [
"# Get some ASC data - Calculate Sensing Matrix \n",
"### also make the radar plots"
]
},

... 325 more lines ...
14880   Mon Sep 16 11:55:58 2019 rikaUpdateIOOWFS loop measurements

[rika, aaron]

We aligned optics of WFS as it was. Now auto-locker is working to lock MC.

But it still doesn't lock. We notice that the c1lsc machine doesn't work. So we run rebootCILSC.sh.

Now we reset the hardware!

17:11

After reset, auto locking didn't work well. Gautum and Aaron reboot slow c1ioo. Then it works, and Gautam returned the MC to a good alignment.

We found the beam is not in the center of the QPD, we (turned off the MC autolocker and MC loop, then) realigned to make beam to get in to the QPD center. Afterwards we start auto locking.

With the WFS on, the maximum MC transmission we observe is 14,700 counts; after the transmission level stabilizes (MC_TRANS pit and yaw brought to 0), the MC transmission is only 14,200 counts. Perhaps the MC_TRANS QPD offsets need adjustment. We relieve the WFS servo of its DC offsets. This is the configuration we'll use for WFS loop measurements this week.

14886   Tue Sep 17 09:41:48 2019 gautamUpdateIOOWFS loop measurements

 But it still doesn't lock. We notice that the c1lsc machine doesn't work. So we run rebootCILSC.sh.
14887   Tue Sep 17 10:34:48 2019 aaronUpdateIOOWFS loop measurements

I'm using the notebooks from rana as a starting point, and making a script to measure and fill the WFS sensing matrix. It lives at /users/aaron/WFS/scripts/WFSsensingMatrix.ipynb for now. Here's what it does; what's been tested is in green, untested is goldenrod, uncoded is fire brick.

1. Sets up an nds connection, listening to the WFS channels and the MC#_PIT/YAW IN1 channels.
2. Loops over the excitation channels. For now, I'm assuming the user is injecting excitations one at a time in awggui; in principle, we could excite the various MC angular dof at several frequencies and take a single measurement, or use the natural frequencies of the suspensions.
1. For each excitation, grab the data
2. Filter the data. I'm using a 30 Hz to 40 Hz cheby filter
3. Take an FFT, hold on to that for future reference
4. Generate an LO at the excitation frequency, and demodulate the signals. Strong low pass.
5. The single-frequency transfer function is now [WFS channel] / [excited MC channel]. Each iteration of this loop generates a column of the sensing matrix.
3. Invert the sensing matrix
4. Populate in the appropriate channels of the WFS_OUTMATRIX

# Grabbing data with nds

To run these on pianosa, I ran (inside the jupyter notebook)

import sys
!{sys.executable} -m pip install astropy --user

I'm getting an error when starting the nds2 connection

conn = nds2.connection('192.168.113.201', 31200)
Failed to establish a connection[INFO: Request SASL authentication protocol]+


I didn't find anything on the elog about this error, but I'm looking at the nds user manual. The problem was, I didn't have a valid Kerberos ticket; I opened one on Pianosa with my albert.einstein (note all caps ligo.org).

kinit aaron.markowitz@LIGO.ORG

I'm now able to run the scripts Rana mentions, but I haven't been able to grab the channels I want (eg C1:SUS-MC1_ASCPIT_IN1_OUT); it says the channel isn't found. When I check how many of the Caltech channels are available (conn.count_channels('C1*')), there are none. I was connecting to nds.ligo.caltech.edu, but this must be the wrong server (it has all the channels for the sites). fb and fb1 (and the IP they point to, 192.168.113.201) cannot be connected to, giving the error 'Error occurred trying to write to socket.'

I recall that in the cryo lab, we need to use port 8088 to get data from cymac1, and indeed substituting 31200 -> 8088 lets me access the C1 channels (I can count the channels), but no matter what time I request, nds tells me there is no data available (gap). Gautam came by and diagnosed that the gaps I'm seeing in the frames' data are real, fb is down (see elog).

# WFS Sensing Matrix Script

## Saving extra channels

Continuing, I'm going to modify the script to grab live data. I'm using the iterate and next methods. I noticed that the MC2_TRANS pit/yaw channels are not saved to frames, even though WFS1/2 pit/yaw are. Since I expect I'll want to lookback at these channels, I followed the instructions for adding a daq channel, uncommenting the following line in /opt/rtcds/caltech/c1/chans/daq/C1IOO.ini:

[C1:IOO-MC2_TRANS_PIT_OUT_DQ]
acquire=1
datarate=512
chnnum=10186
datatype=4
[C1:IOO-MC2_TRANS_YAW_OUT_DQ]
acquire=1
chnnum=10189
datarate=512
datatype=4

I made a backup of the old version of this .ini file, which can be found in /users/aaron/backups/190917_C1IOO.ini. I did not remake the model, as I couldn't find the c1ioo model in /opt/rtcds/caltech/c1/userapps/trunk or from the matlab command prompt. I restarted the fb via telnet, but didn't restart the model or check the svn (got an error?). The _DQ channels are now reachable on dataviewer, so things seem to be working.

## awgpy

I also tried importing cdsutils, so I can control awg in the same script that we read out the sensing matrix, but I'm getting the python3 error when I import cdsutils:

No module name '__version'

I tried pip upgrading cdsutils, but it's already up-to-date. I get the above error even if I switch to a python 2 kernel; cdsutils is installed in the python2.7 directory, so I don't know why pip is finding it when I'm running a python 3 kernel. I can move on from this for now, but it would be useful to be able to script the excitation along with the measurement.

# Changes to the user environment

## jupyter on donatella

Tangentially related, Rika wanted to be running some jupyter notebooks while working on donatella. I ran, on donatella:

conda install jupyter

hm, that didn't work. Also jupyter is installed when you install conda, so I'm not sure how there is a version of conda but not of jupyter. I also see that pip and pip3 are not recognized commands on donatella.

## scipy on pianosa

I noticed that some of the functions in the scipy signal processing toolbox were out of date on pianosa. The cheby and welch filters now accept additional kwargs (for eg, before you needed to give IIR filter methods a cutoff frequency normalized to the Nyquist rate, but now you can give it the frequencies and sampling rate separately).

I want to update this package, but I hesitate to break everyone's existing scripts.

14888   Tue Sep 17 10:47:44 2019 rikaUpdateIOOWFS loop measurements

[aaron, rika]

Once stop the auto-locker and realigned to make beam to get into QPD again.

After we lock MC, we took TFs from suspension MC1/2/3 PIT/YAW to WFS1/2 PIT/YAW.

-----

Diagnotics test tools

range: 7 Hz to 50 Hz

avarage=61

Column 0: WFS2_PIT   1: WFS2_YAW   2:WFS1_PIT   3: WFS1_YAW   4: TRANCE_PIT   5:TRANCE_YAW

-----

I'm wondering weather the MC1data I saved is correct, becouse I found the channel was changed when I exported MC2 data. So I took MC1 data again.

We got all data for TFs already.  Each data is devided to real part and imaginary part. Then we are arranging the datas to obtain TFs.

TF of MC2 is attachiment 1. So tomorrow, I make other TF.

 Quote: [rika, aaron] We aligned optics of WFS as it was. Now auto-locker is working to lock MC. But it still doesn't lock. We notice that the c1lsc machine doesn't work. So we run rebootCILSC.sh.   Now we reset the hardware!   17:11 After reset, auto locking didn't work well. Gautum and Aaron reboot slow c1ioo. Then it works, and Gautam returned the MC to a good alignment. We found the beam is not in the center of the QPD, we (turned off the MC autolocker and MC loop, then) realigned to make beam to get in to the QPD center. Afterwards we start auto locking. With the WFS on, the maximum MC transmission we observe is 14,700 counts; after the transmission level stabilizes (MC_TRANS pit and yaw brought to 0), the MC transmission is only 14,200 counts. Perhaps the MC_TRANS QPD offsets need adjustment. We relieve the WFS servo of its DC offsets. This is the configuration we'll use for WFS loop measurements this week.

Attachment 1: MC2.pdf
14896   Wed Sep 18 14:45:52 2019 rikaUpdateIOOWFS loop measurements

[aaron, rika]

## Gettng TFs

In the data we got yesterday, we can see some filter's effect.

But it is not good coherence above 10Hz, so we mesured again. And this time we save the data as xml file.

And also we chaned the frequency regions broader to watch corner frequency of suspension.

-----

Diagnotics test tools

range: 0.1 Hz to 100 Hz

points: 120

Amplitude: 1000

----

but at low frequency, the mode maching cavity was unloked cause of too much shaking.

So, we saw single frequency TF, and searched the good amplitude.

First, I tried to get TF @0.1~1 Hz .

-----

0.1 to 1 Hz

points: 61 (I think it's too much becous it takes about an hour)

amplitude: 5

-----

The TFs and coherence of MC1/PIT to each QPD is below. [above window: coherence, below: TF]

During the mesurement, something happened @0.2-0.3Hz so I stopped it.

We found the coherence of WFS1P and WFS2Y is not good, but others are good.

we guess that it could come from alignment which made Q chainging to small.

Finaly, I also got the  .xml data of MC1P 1 Hz to 10 Hz. In this time,

-----

1 to 10 Hz

points: 41

amplitude: 90

-----

## Making matrics

Now we took single frequency 6 TFs (MC1/2/3 PIT/YAW) @7Hz (Because this frequency has good coherence in all channel).

Aaron wrote the script using dtt to making matrics.

Quote:

[aaron, rika]

Once stop the auto-locker and realigned to make beam to get into QPD again.

After we lock MC, we took TFs from suspension MC1/2/3 PIT/YAW to WFS1/2 PIT/YAW.

-----

Diagnotics test tools

range: 7 Hz to 50 Hz

avarage=61

Column 0: WFS2_PIT   1: WFS2_YAW   2:WFS1_PIT   3: WFS1_YAW   4: TRANCE_PIT   5:TRANCE_YAW

-----

I'm wondering weather the MC1data I saved is correct, becouse I found the channel was changed when I exported MC2 data. So I took MC1 data again.

We got all data for TFs already.  Each data is devided to real part and imaginary part. Then we are arranging the datas to obtain TFs.

TF of MC2 is attachiment 1. So tomorrow, I make other TF.

 Quote: [rika, aaron] We aligned optics of WFS as it was. Now auto-locker is working to lock MC. But it still doesn't lock. We notice that the c1lsc machine doesn't work. So we run rebootCILSC.sh.   Now we reset the hardware!   17:11 After reset, auto locking didn't work well. Gautum and Aaron reboot slow c1ioo. Then it works, and Gautam returned the MC to a good alignment. We found the beam is not in the center of the QPD, we (turned off the MC autolocker and MC loop, then) realigned to make beam to get in to the QPD center. Afterwards we start auto locking. With the WFS on, the maximum MC transmission we observe is 14,700 counts; after the transmission level stabilizes (MC_TRANS pit and yaw brought to 0), the MC transmission is only 14,200 counts. Perhaps the MC_TRANS QPD offsets need adjustment. We relieve the WFS servo of its DC offsets. This is the configuration we'll use for WFS loop measurements this week.

Attachment 1: Screenshot_from_2019-09-18_18-15-34.png
14957   Tue Oct 8 20:39:42 2019 aaronUpdateIOOWFS loop measurements

I installed nds2 on donatello with yum, but still can't import nds2.

14958   Wed Oct 9 09:37:28 2019 aaronUpdateIOOWFS loop measurements

I installed nds2 again, this time successfully with

conda install -c conda-forge python-nds2-client

14868   Tue Sep 10 15:41:37 2019 aaronUpdateIOOWFS measurements

[rika, aaron, rana]

We are getting the MC locked in anticipation of making some WFS transfer function measurements.

The PSL screen was all white boxes, so I keyed the PSL crate and burt restored the settings from 11:19am Sep 5 (somewhat earlier than we started rebooting computers). Following this, I ran Milind's unstick.py and then the PSL autolocker script; both worked on the first go, great work Milind!

The modecleaner autolocking script is having substantially more trouble. Rana found that pitch and yaw sliders for all MC optics have been swapped--we think it's because the camera at MC2 has been rotated. Note that for now, sliding pitch gives a change in yaw, and sliding yaw changes pitch.

## Improving MC alignment

We noticed that with the WFS servo on, the modecleaner would be well aligned for a while (MC trans ~ 14000), only to lose lock after several minutes. We held the MC2_TRANS_PIT/YAW outputs at 0, so the MC2 QPD does not affect the WFS loop; the beam is well centered on WFS1/2, but not on the MC2 QPD, and with this signal out of the loop MC TRANS recovers to ~15000 counts (consistent with the quiet times over the last 90 days, see attachment 2). Attachment 1 shows the MC lock degrading, followed by some noise where we lost lock, and finally a visible increase in MC trans when we remove the MC2 QPD from the WFS loop.

### mode cleaner alignment setting

MC1 Pich 4.4762     Yow 4.4669

MC2 Pich 3.7652     Yow -1.5482

MC3 Pich -0.4159    Yow 1.1477

After automatic locking MC, we stopped automatical locking and took alignment to the center of QPD.

And then again did the automatic locking MC. Finaly Rana move to best alignment.

### Mode cleaner Alignment Setting

MC1 Pich 4.4942   Yow 4.6956

MC2 Pich 3.7652   Yow -1.5600

MC3 Pich -0.3789   Yow 1.1477

## Measured sine response

We used diaggui to measure the response of WFS1/WFS2/MC2 pitch (yaw) to excitations in MC1/MC2/MC3 pitch (yaw). Seeing fluctuations of amplitude ~1 on the MCX_PIT/YAW_OUT channels, we used an amplitude 0.01 excitation at 20 Hz. We will work on scripting some of this tomorrow.

Attachment 1: Screenshot_from_2019-09-10_18-51-28.png
Attachment 2: mctrend_190910.png
14871   Wed Sep 11 10:26:56 2019 aaronUpdateIOOWFS measurements

## Gameplan

We should also have a plan for the next couple weeks so we are organized; heavily adapted from. Here's what I'm thinking this morning:

1. Construct the input/output matrix for the WFS. (basically, what we did yesterday)
1. Measure a transfer function of MC[1, 2, 3]_[PIT, YAW] to [WFS1, WFS2, MC2_TRANS]_[PIT, YAW]. The transfer function above the loop bandwidth (few seconds BW, so we will excite >~ 10 Hz) characterizes the response of the sensor to the excitation.
2. Invert the resulting 3x3 matrix and populate the inverted matrix at WFS_OUTMATRIX. This will map the WFS basis to the MC optics' pit/yaw basis.
3. Script this process. If we make changes (for example, moving the telescoping lenses) to make this matrix more diagonal, we'll want to do these steps many times.
2. Characterizing the loop
1. Optimize the demodulation phase -- we want to minimize the signal in Q. This should also be automated. I found documentation in the white Wave Front Sensing binder
1. Misalign a mirror in pitch or yaw, and rotate the phase to minimize the magnitude of Q (maximize I); this angle is 'R' on the WFSx_SETTINGS screen.
2. We should measure a step response applied to each angular dof of the MC optics.
3. Guoy Phase Calibration
3. Characterizing / Calibrating the WFS heads
1. The DCC has LIGO test procedures for their WFS RFPD, as does the white binder; the following checks are relevant for our WFS, and this is how I think we should carry them out (not identical to the procedure as written in the document). For many of these, we'll want to set up the JenneAM laser with a network analyzer for RF modulation.
1. DC path transimpedance
1. Measure the DC power of JenneAM with a power meter, and direct the beam to each of the QPD quadrants. Make sure the beam fits on a single quadrant.
2. This will give us the product of the PD efficiency and DC transimpedance gain
3. Last time this was measured (white WFS binder)
2. notch tuning -- we are going to measure the TF, but I won't tune it without someone as ancient as the electronics
1. Using the network analyzer, measure a transfer function from the laser AM to the QPD head's RF output
1. Is there a pickoff available? The LIGO testing procedures recommend a FET probe
2. We should do this while measuring the DC transimpedance for each quadrant
3. notch rejection ratios
1. While taking the RF transfer function, use the delta marker to record the difference between the notch and the RF operating frequency.
4. RF transimpedance
1. Illuminate the PD with white light from an incandescent bulb (a shot-noise limited source)
1. 6-10 mA of photocurrent should be generated
2. Use an RF spectrum analyzer and low noise RF pre-amplifier (gain ~20dB) to measure the shot noise limited spectrum
3. A piece of scotch tape can be used to make the light uniformly illuminate the QPD
4. Convert this RF PSD to an rms amplitude (voltage) spectral density, and also note the DC photocurrent. This can be used to calculate the RF transimpedance with
1. $Z_\mathrm{RF} = \sqrt{\frac{V_\mathrm{rms}^2I_\mathrm{DC}}{3.2\times 10^{-19}}}$
5. Shot noise limited input sensitivity
1. Measure the RF PSD with the beam blocked and light off; this is the dark photocurrent, and can be used to calculate the shot noise limited sensitivity.

References:

• Binders of documents about the 40m WFS
• LIGO ISC WFS RFPD test procedure (T1200347 is dual frequency, T1200380 is single frequency)
• The associated datasheet template is in T1200381
• Wavefront Sensor (T960111). This document even has a calibration protocol with forms to fill in during testing, so I've printed an extra copy of that appendix.

## Automation

It would be good to script some of what we did yesterday. I'm checking out some scripts I'd used for Qryo and armloss measurements to remember the best way to do this.

• Existing WFS scripts (I didn't try these)
• WFS_DC_offsets -- sets the WFS QPD dark offsets
• block beam, then run script
• MC2_TRANS_offsets -- sets the MC2 transmission offset (why isn't this in the same script as WFS_DC_offsets?)
• MC should be aligned, beams centered on WFS, WFS servo off
• mcWFSallowOn(Off) -- turns on (off) the ASC filter module outputs
• mcwfshold -- turns off the input to WFS servos, but holds the current values of MC optic biases
• mcwfsoff -- turns off the mc wfs loop
• First, turns off the WFS outputs (eg WFS1_PIT OUTPUT)
• Turns off the MC WFS input gains
• Holds the WFS loop outputs

## Miscellany

I noticed yesterday that the PSL_shutterqst box is white, and I've seen timeout requests when eg the reboot script tries to open/close the PSL shutter. It seems like a shutter that should open, so I should find the aux machine to restart it.

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