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ID Date Author Type Category Subject
16209   Thu Jun 17 11:45:42 2021 Anchal, PacoUpdateSUSMC1 Gave trouble again

TL;DR

MC1 LL Sensor showed signs of fluctuating large offsets. We tried to find the issue in the box but couldn't find any. On power cycling, the sensor got back to normal. But in putting back the box, we bumped something and c1susaux slow channels froze. We tried to reboot it, but it didn't work and the channels do not exist anymore.

Today morning we came to find that IMC struggled to lock all night (See attachment 1). We kind of had an indication yesterday evening that MC1 LL Sensor PD had a higher variance than usual and Paco had to reset WFS offsets because they had integrated the noise from this sensor. Something similar happened last night, that a false offset and its fluctuation overwhelmed WFS and MC1 got misaligned making it impossible for IMC to get lock.

In the morning, Paco again reset the WFS offsets but not we were sure that the PD variance from MC1 LL osem was very high. See attachment 2 to see how only 1 OSEM is showing higher noise in comparison to the other 4 OSEMs. This behavior is similar to what we saw earlier in 16138 but for UL sensor. Koji and I fixed it in 16139 and we tested all other channels too.

So, Paco and I, went ahead and took out the MC1 satellite amplifier box S2100029 D1002812, opened the top, and checked all the PD channel testpoints with no input current. We didn't find anything odd. Next we checked the LED dirver circuit testpoints with LED OUT and GND shorted. We got 4.997V on all LED MON testpoints which indicate normal functioning.

We just hooked back everything on the MC1 satellit box and checked the sensor channels again on medm screens. To our surprise, it started functioning normally. So maybe, just a power cycling was required but we still don't know what caused this issue.

BUT when I (Anchal) was plugging back the power cables and D25 connectors on the back side in 1X4 after moving the box back into the rack, we found that the slow channels stopped updating. They just froze!

We got worried for some time as the negative power supply indicator LEDs on the acromag chassis (which is just below the MC1 satellite box) were not ON. We checked the power cables and had to open the side panel of the 1X4 rack to check how the power cables are connected. We found that there is no third wire in the power cables and the acromag chassis only takes in single rail supply. We confirmed this by looking at another acromag chassis on Xend. We pasted a note on the acromag chassis for future reference that it uses only positive rails and negative LED monitors are not usually ON.

Back to solving the frozen acromag issue, we conjectured that maybe the ethernet connection is broken. The DB25 cables for the satellite box are bit short and pull around other cables with it when connected. We checked all the ethernet cabling, it looked fine. On c1susaux computer, we saw that the monitor LED for ethernet port 2 which is connected to acromag chassis is solid ON while the other one (which is probably connection to the switch) is blinking.

We tried doing telnet to the computer, it didn't work. The host refused connection from pianosa workstation. We tried pinging the c1susaux computer, and that worked. So we concluded that most probably, the epics modbus server hosting the slow channels on c1susaux is unable to communicate with acromag chassis and hence the solid LED light on that ethernet port instead of a blinking one. We checked computer restart procedure page for SLOW computers on wiki and found that it said if telnet is not working, we can hard reboot the computer.

We hard reboot the computer by long pressing the power button and then presssing it back on. We did this process 3 times with the same result. The ethernet port 2 LED (Acromag chassis) would blink but the ethernet port 1 LED (connected to switch) would not turn ON. We now can not even ping the machine now, let alone telnet into it. All SUS slow monitor channels are not present now ofcourse. We also tried once pressing the reset button (which the manual said would reboot the machine), but we got the same outcome.

Now, we decided to stop poking around until someone with more experience can help us on this.

Bottomline: We don't know what caused the LL sensor issue and hence it has not been fixed. It can happen again. We lost all C1SUSAUX slow channels which are the OSEM and COIL slow monitor channels for PRM, BS, ITMX, ITMY, MC1, MC2 and MC3.

Attachment 1: SummaryScreenShot.png
16210   Thu Jun 17 16:37:23 2021 Anchal, PacoUpdateSUSc1susaux computer rebooted

Jon suggested to reboot the acromag chassis, then the computer, and we did this without success. Then, Koji suggested we try running ifup eth0, so we ran sudo /sbin/ifup eth0 and it worked to put c1susaux back in the martian network, but the modbus service was still down. We switched off the chassis and rebooted the computer and we had to do sudo /sbin/ifup eth0 again (why do we need to do this manually everytime?). Switched on the chassis but still no channels. sudo systemctl status modbusioc.service' gave us inactive (dead) status. So  we ran sudo systemctl restart modbusioc.service'.

The status became:

● modbusIOC.service - ModbusIOC Service via procServ
start condition failed at Thu 2021-06-17 16:10:42 PDT; 12min ago
ConditionPathExists=/opt/rtcds/caltech/c1/burt/autoburt/latest/c1susaux.snap was not met

After another iteration we finally got a modbusIOC.service OK status, and we then repeated Jon's reboot procedure. This time, the acromags were on but reading 0.0, so we just needed to run sudo /sbin/ifup eth1and finally some sweet slow channels were read. As a final step we burt restored to 05:19 AM today c1susaux.snap file and managed to relock the IMC >> will keep an eye on it.... Finally, in the process of damping all the suspended optics, we noticed some OSEM channels on BS and PRM are reading 0.0 (they are red as we browse them)... We succeeded in locking both arms, but this remains an unknown for us.

16212   Thu Jun 17 22:25:38 2021 KojiUpdateSUSNew electronics: Sat Amp / Coil Drivers

It is a belated report: We received 5 more sat amps on June 4th. (I said 7 more but it was 6 more) So we still have one more sat amp coming from Todd.

- 1 already delivered long ago
- 8 received from Todd -> DeLeone -> Chub. They are in the lab.
- 11 units on May 21st
- 5 units on Jun 4th
Total 1+8+11+5 = 25
1 more unit is coming

 Quote: 11 new Satellite Amps were picked up from Downs. 7 more are coming from there. I have one spare unit I made. 1 sat amp has already been used at MC1. We had 8 HAM-A coil drivers delivered from the assembling company. We also have two coil drivers delivered from Downs (Anchal tested)

Attachment 1: P_20210604_231028.jpeg

We checked back in time to see how the BS and PRM OSEM slow channels are zero. It was clear that they became zero when we worked on this issue on June 17th, Thursday. So we simply went back and power cycled the c1susaux acromag chassis. After that, we had to log in to c1susaux computer and run

sudo /sbin/ifdown eth1
sudo /sbin/ifup eth1

This restarted the ethernet port acromag chassis is connected to. This solved this issue and we were able to see all the slow channels in BS and PRM.

But then, we noticed that the OPLEV of ITMX is unable to read the position of the beam on the QPD at all. No light was reaching the QPD. We went in, opened the ITMX table cover and confirmed that the return OPLEV beam is way off and is not even hitting one of the steering mirrors that brings it to the QPD. We switched off the OPLEV contribution to the damping.

We did burt restore to 16th June morning using
burtwb -f /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2021/Jun/16/06:19/c1susaux.snap -l /tmp/controls_1210622_095432_0.write.log -o /tmp/controls_1210622_095432_0.nowrite.snap -v

This did not solve the issue.

Then we noticed that the OSEM signals from ITMX were saturated in opposite directions for Left and Right OSEMs. The Left OSEM fast channels are saturated to 1.918 um for UL and 1.399 um for LL, while both right OSEM channels are bottomed to 0 um. On the other hand, the acromag slow PD monitors are showing 0 on the right channels but 1097 cts on UL PDMon and 802 cts in LL PD Mon. We actually went in and checked the DC voltages from the PD input monitor LEMO ports on the ITMX dewhitening board D000210-A1 and measured non-zero voltages across all the channels. Following is a summary:

C1-SUS-ITMX_XXSEN_OUT
C1-SUS-ITMX_xxPDMon
(Slow Acromag Monitors) (cts)
Multimeter measurements at input to Dewhitening Boards
(V)
UL 1.918 1097 0.901
LL 1.399 802 0.998
UR 0 0 0.856
LR 0 0 0.792
SD 0.035 20 0.883

We even took out the 4-pin LEMO outputs from the dewhitening boards that go to the anti-aliasing chassis and checked the voltages. They are same as the input voltages as expected. So the dewhitening board is doing its job fine and the OSEMs are doing their jobs fine.

It is weird that both the ADC and the acromags are reading these values wrong. We believe this is causing a big yaw offset in the ITMX control signal causing the ITMX to turn enough make OPLEV go out of range. We checked the CDS FE status (attachment 1). Other than c1rfm showing a yellow bar (bit 2 = GE FANUC RFM card 0) in RT Net Status, nothing else seems wrong in c1sus computer. c1sus FE model is running fine. c1x02 (the lower level model) does show a red bar in TIM which suggests some timing issue. This is present in c1x04 too.

### Bottomline:

Currently, the ITMX coil outputs are disabled as we can't trust the OSEM channels. We're investigating more why any of this is happening. Any input is welcome.

Attachment 1: CDS_FE_Status.png

After sliding the alignment bias around and browsing through elog while searching for "stuck" we concluded the ITMX osems needed to be freed. To do this, the procedure is to slide the alignment bias back and forth ("shaking") and then as the OSEMs start to vary, enable the damping. We did just this, and then restored the alignment bias sliders slowly into their original positions. Attachment 1 shows the ITMX OSEM sensor input monitors throughout this procedure.

At the end, since MC has trouble catching lock after opening PSL shutter, I tried running burt restore the ioo to 2021/Jun/17/06:19/c1iooepics.snap but the problem persists

Attachment 1: shake_and_damp.png
16222   Wed Jun 23 09:05:02 2021 AnchalUpdateSUSMC lock acquired back again

MC was unable to acquire lock because the WFS offsets were cleared to zero at some point and because of that MC was very misaligned to be able to catch back lock. In such cases, one wants the WFS to start accumulating offsets as soon as minimal lock is attained so that the mode cleaner can be automatically aligned. So I did following that worked:

• Made the C1:IOO-WFS_TRIG_WAIT_TIME (delay in WFS trigger) from 3s to 0s.
• Reduced C1:IOO-WFS_TRIGGER_THRESH_ON (Switchin on threshold) from 5000 to 1000.
• Then as soon as a TEM00 was locked with poor efficiency, the WFS loops started aligning the optics to bring it back to lock.
• After robust lock has been acquired, I restored the two settings I changed above.
 Quote: At the end, since MC has trouble catching lock after opening PSL shutter, I tried running burt restore the ioo to 2021/Jun/17/06:19/c1iooepics.snap but the problem persists

16223   Thu Jun 24 16:40:37 2021 KojiUpdateSUSMC lock acquired back again

[Koji, Anchal]

The issue of the PD output was that the PD whitened outputs of the sat amp (D080276) are differential, while the successive circuit (D000210 PD whitening unit) has the single-ended inputs. This means that the neg outputs (D080276 U2) have always been shorted to GND with no output R. This forced AD8672 to work hard at the output current limit. Maybe there was a heat problem due to this current saturation as Anchal reported that the unit came back sane after some power-cycling or opening the lid. But the heat issue and the forced differential voltage to the input stage of the chip eventually cause it to fail, I believe.

Anchal came up with the brilliant idea to bypass this issue. The sat amp box has the PD mon channels which are single-ended. We simply shifted the output cables to the mon connectors. The MC1 sus was nicely damped and the IMC was locked as usual. Anchal will keep checking if the circuit will keep working for a few days.

Attachment 1: P_20210624_163641_1.jpg
16252   Wed Jul 21 14:50:23 2021 KojiUpdateSUSNew electronics

Jun 29, 2021 BIO I/F 6 units
Jul 19, 2021 PZT Drivers x2 / QPD Transimedance amp x2

Attachment 1: P_20210629_183950.jpeg
Attachment 2: P_20210719_135938.jpeg
16281   Tue Aug 17 04:30:35 2021 KojiUpdateSUSNew electronics

Aug 17, 2021 2x ISC Whitening

Delivered 2x Sat Amp board to Todd

Attachment 1: P_20210816_234136.jpg
Attachment 2: P_20210816_235106.jpg
Attachment 3: P_20210816_234220.jpg
16296   Wed Aug 25 08:53:33 2021 JordanUpdateSUS2" Adapter Ring for SOS Arrived 8/24/21

8 of the 2"->3" adapter rings (D2100377) arrived from RDL yesterday. I have not tested the threads but dimensional inspection on SN008 cleared. Parts look very good. The rest of the parts should be shipping out in the next week.

Attachment 1: 20210824_152259.jpg
Attachment 2: 20210824_152259.jpg
Attachment 3: 20210824_152308.jpg
16326   Tue Sep 14 16:12:03 2021 JordanUpdateSUSSOS Tower Hardware

Yehonathan noticed today that the silver plated hardware on the assembled SOS towers had some pretty severe discoloration on it. See attached picture.

These were all brand new screws from UC components, and have been sitting on the flow bench for a couple months now. I believe this is just oxidation and is not an issue, I spoke to Calum as well and showed him the attached picture and he agreed it was likely oxidation and should not be a problem once installed.

He did mention if there is any concern from anyone, we could take an FTIR sample and send it to JPL for analysis, but this would cost a few hundred dollars.

I don't believe this to be an issue, but it is odd that they oxidized so quickly. Just wanted to relay this to everyone else to see if there was any concern.

Attachment 1: 20210914_160111.jpg
16328   Tue Sep 14 17:14:46 2021 KojiUpdateSUSSOS Tower Hardware

Yup this is OK. No problem.

16342   Fri Sep 17 20:22:55 2021 KojiUpdateSUSEQ M4.3 Long beach

EQ  M4.3 @longbeach
2021-09-18 02:58:34 (UTC) / 07:58:34 (PDT)
https://earthquake.usgs.gov/earthquakes/eventpage/ci39812319/executive

• All SUS Watchdogs tripped, but the SUSs looked OK except for the stuck ITMX.
• Damped the SUSs (except ITMX)
• IMC automatically locked
• Turned off the damping of ITMX and shook it only with the pitch bias -> Easily unstuck -> damping recovered -> realignment of the ITMX probably necessary.
• Done.
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
16364   Wed Sep 29 09:36:26 2021 JordanUpdateSUS2" Adapter Ring Parts for SOS Arrived 9/28/21

The remaining machined parts for the SOS adapter ring have arrived. I will inspect these today and get them ready for C&B.

Attachment 1: 20210929_092418.jpg
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
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.

[Paco]

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.

16384   Wed Oct 6 15:04:36 2021 HangUpdateSUSPRM L2P TF measurement & Fisher matrix analysis

[Paco, Hang]

Yesterday afternoon Paco and I measured the PRM L2P transfer function. We drove C1:SUS-PRM_LSC_EXC with a white noise in the 0-10 Hz band (effectively a white, longitudinal force applied to the suspension) and read out the pitch response in C1:SUS-PRM_OL_PIT_OUT. The local damping was left on during the measurement. Each FFT segment in our measurement is 32 sec and we used 8 non-overlapping segments for each measurement. The empirically determined results are also compared with the Fisher matrix estimation (similar to elog:16373).

Results:

Fig. 1 shows one example of the measured L2P transfer function. The gray traces are measurement data and shaded region the corresponding uncertainty. The olive trace is the best fit model.

Note that for a single-stage suspension, the ideal L2P TF should have two zeros at DC and two pairs of complex poles for the length and pitch resonances, respectively. We found the two resonances at around 1 Hz from the fitting as expected. However, the zeros were not at DC as the ideal, theoretical model suggested. Instead, we found a pair of right-half plane zeros in order to explain the measurement results. If we cast such a pair of right-half plane zeros into (f, Q) pair, it means a negative value of Q. This means the system does not have the minimum phase delay and suggests some dirty cross-coupling exists, which might not be surprising.

Fig. 2 compares the distribution of the fitting results for 4 different measurements (4 red crosses) and the analytical error estimation obtained using the Fisher matrix (the gray contours; the inner one is the 1-sigma region and the outer one the 3-sigma region). The Fisher matrix appears to underestimate the scattering from this experiment, yet it does capture the correlation between different parameters (the frequencies and quality factors of the two resonances).

One caveat though is that the fitting routine is not especially robust. We used the vectfit routine w/ human intervening to get some initial guesses of the model. We then used a standard scipy least-sq routine to find the maximal likelihood estimator of the restricted model (with fixed number of zeros and poles; here 2 complex zeros and 4 complex poles). The initial guess for the scipy routine was obtained from the vectfit model.

Fig. 3 shows how we may shape our excitation PSD to maximize the Fisher information while keeping the RMS force applied to the PRM suspension fixed. In this case the result is very intuitive. We simply concentrate our drive around the resonance at ~ 1 Hz, focusing on locations where we initially have good SNR. So at least code is not suggesting something crazy...

Fig. 4 then shows how the new uncertainty (3-sigma contours) should change as we optimize our excitation. Basically one iteration (from gray to olive) is sufficient here.

We will find a time very recently to repeat the measurement with the optimized injection spectrum.

Attachment 1: prm_l2p_tf_meas.pdf
Attachment 2: prm_l2p_fisher_vs_data.pdf
Attachment 3: prm_l2p_Pxx_evol.pdf
Attachment 4: prm_l2p_fisher_evol.pdf
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.

16388   Fri Oct 8 17:33:13 2021 HangUpdateSUSMore PRM L2P measurements

[Raj, Hang]

We did some more measurements on the PRM L2P TF.

We tried to compare the parameter estimation uncertainties of white vs. optimal excitation. We drove C1:SUS-PRM_LSC_EXC with "Normal" excitation and digital gain of 700.

For the white noise exciation, we simply put a butter("LowPass",4,10) filter to select out the <10 Hz band.

For the optimal exciation, we use butter("BandPass",6,0.3,1.6) gain(3) notch(1,20,8) to approximate the spectral shape reported in elog:16384. We tried to use awg.ArbitraryLoop yet this function seems to have some bugs and didn't run correctly; an issue has been submitted to the gitlab repo with more details. We also noticed that in elog:16384, the pitch motion should be read out from C1:SUS-PRM_OL_PIT_IN1 instead of the OUT channel, as there are some extra filters between IN1 and OUT. Consequently, the exact optimal exciation should be revisited, yet we think the main result should not be altered significantly.

While a more detail analysis will be done later offline, we post in the attached plot a comparison between the white (blue) vs optimal (red) excitation. Note in this case, we kept the total force applied to the PRM the same (as the RMS level matches).

Under this simple case, the optimal excitation appears reasonable in two folds.

First, the optimization tries to concentrate the power around the resonance. We would naturally expect that near the resonance, we would get more Fisher information, as the phase changes the fastest there (i.e., large derivatives in the TF).

Second, while we move the power in the >2 Hz band to the 0.3-2 Hz band, from the coherence plot we see that we don't lose any information in the > 2 Hz region. Indeed, even with the original white excitation, the coherence is low and the > 2 Hz region would not be informative. Therefore, it seems reasonable to give up this band so that we can gain more information from locations where we have meaningful coherence.

Attachment 1: Screenshot_2021-10-08_17-30-52.png
16389   Mon Oct 11 11:13:04 2021 ranaUpdateSUSMore PRM L2P measurements

For the oplev, there are DQ channels you can use so that its possible to look back in the past for long measurements. They have names like PERROR

16390   Mon Oct 11 13:59:47 2021 HangUpdateSUSMore PRM L2P measurements

We report here the analysis results for the measurements done in elog:16388

Figs. 1 & 2 are respectively measurements of the white noise excitation and the optimized excitation. The shaded region corresponds to the 1-sigma uncertainty at each frequency bin. By eyes, one can already see that the constraints on the phase in the 0.6-1 Hz band are much tighter in the optimized case than in the white noise case.

We found the transfer function was best described by two real poles + one pair of complex poles (i.e., resonance) + one pair of complex zeros in the right-half plane (non-minimum phase delay). The measurement in fact suggested a right-hand pole somewhere between 0.05-0.1 Hz which cannot be right. For now, I just manually flipped the sign of this lowest frequency pole to the left-hand side. However, this introduced some systematic deviation in the phase in the 0.3-0.5 Hz band where our coherence was still good. Therefore, a caveat is that our model with 7 free parameters (4 poles + 2 zeros + 1 gain as one would expect for an ideal signal-stage L2P TF) might not sufficiently capture the entire physics.

In Fig. 3 we showed the comparison of the two sets of measurements together with the predictions based on the Fisher matrix. Here the color gray is for the white-noise excitation and olive is for the optimized excitation. The solid and dotted contours are respectively the 1-sigma and 3-sigma regions from the Fisher calculation, and crosses are maximum likelihood estimations of each measurement (though the scipy optimizer might not find the true maximum).

Note that the mean values don't match in the two sets of measurements, suggesting potential bias or other systematics exists in the current measurement. Moreover, there could be multiple local maxima in the likelihood in this high-D parameter space (not surprising). For example, one could reduce the resonant Q but enhance the overall gain to keep the shoulder of a resonance having the same amplitude. However, this correlation is not explicit in the Fisher matrix (first-order derivatives of the TF, i.e., local gradients) as it does not show up in the error ellipse.

In Fig. 4 we show the further optimized excitation for the next round of measurements. Here the cyan and olive traces are obtained assuming different values of the "true" physical parameter, yet the overall shapes of the two are quite similar, and are close to the optimized excitation spectrum we already used in elog:16388

Attachment 1: prm_l2p_tf_meas_white.pdf
Attachment 2: prm_l2p_tf_meas_opt.pdf
Attachment 3: prm_l2p_fisher_vs_data_white_vs_opt.pdf
Attachment 4: prm_l2p_Pxx_evol_v2.pdf
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??

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.

 Quote: 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?

16419   Thu Oct 21 11:38:43 2021 JordanUpdateSUSStandoffs for Side Magnet on 3" Adapter Ring SOS Assembly

I had 8 standoffs made at the Caltech chemistry machine shop to be used as spacers for the side magnets on the 3" Ring assembly. This is to create enough clearance between the magnet and the cap screws directly above on the wire clamp.

These are 0.075" diameter by .10" length. Putting them through clean and bake now.

Attachment 1: Magnet_Standoffs.jpg
16447   Wed Nov 3 16:55:23 2021 Ian MacMillanSummarySUSSUS Plant Plan for New Optics

[Ian, Tega, Raj]

This is the rough plan for the testing of the new suspension models with the created plant model. We will test the suspensions on the plant model before we implement them into the full

• Get State-space matrices from the surf model for the SOS. Set up simplant model on teststand
• The state-space model is only 3 degrees of freedom. (even the surf's model)
• There are filter modules that have the 6 degrees of freedom for the suspensions. We will use these instead. I have implemented them in the same suspension model that would hold the state space model. If we ever get the state space matrices then we can easily substitute them.
• Load new controller model onto test stand. This new controller will be a copy of an existing suspension controller.
• Hook up controller to simplant.  These should form a closed loop where the outputs from the controller go into the plant inputs and the plant outputs go to the controller inputs.
• Do tests on set up.
• Look at the step response for each degree of freedom. Then compare them to the results from an existing optic.
• Also, working with Raj let him do the same model in python then compare the two.
• Make sure that the data is being written to the local frame handler.

MEDM file location

/opt/rtcds/userapps/release/sus/common/medm/hsss_tega_gautam

run using

For ITMX display, use:

16449   Thu Nov 4 18:29:51 2021 TegaUpdateSUSSetting up suspension test model

[Ian,Tega]

Today we continued working on setting up the 6 degrees of freedom model for testing the suspension which we copied over from  "/cvs/cds/rtcds/userapps/release/sus/c1/models/c1sup.mdl" to c1sp2.mdl in the same folder. We then changed the host from c1lsc to c1sus2, changed cpu # from 7 to 3 bcos c1sus2 has 6 cores. Then ran the following commands to build and install the model on c1sus2:

$ssh c1sus2$ rtcds make c1sp2

\$ rtcds install c1sp2

where we encountered the following installation error:

ERROR: This node 62 is already installed as:

hostname=c1lsc

system=c1sup

The new entry you are trying to write is as follows:

hostname=c1sus2

system=c1sp2

This script will not overwrite existing entries in testpoint.par

If this is an attempt to move an existing system from one host to another,

please remove conflicting entry from testpoint.par file

It seems that changing the model name and host did not change the node allocation, so will remove the previous entries in testpoint.par to see if that helps. After deleting the following lines

[C-node62]
hostname=c1lsc
system=c1sup

from the file "/opt/rtcds/caltech/c1/target/gds/param/testpoint.par", the installation went fine and the above entries were replaced by

[C-node62]
hostname=c1sus2
system=c1sp2

BTW, I now believe the reason we had the node conflict earlier was bcos both models still had the same value of  dcuid=62, so I think changing this value in our model file would be a better solution. Work is ongoing.

16451   Fri Nov 5 12:49:32 2021 ranaUpdateSUSSetting up suspension test model

Please don't put it on c1sus2. Put it on the completely independent test stand as we discussed Wednesday. You must test the controller on the simplant and verify that they thing is stable and works, before putting it in the 40m network.

16457   Mon Nov 8 17:52:22 2021 Ian MacMillanUpdateSUSSetting up suspension test model

[Ian, Tega]

We combined a controler and a plant model into a single modle (See first attachment) called x1sus_cp.mdl in the userapps folder of the cymac in c1sim. This model combines 2 blocks: the controler block which is used to control the current optics and is found in cvs/cds/rtcds/userapps/release/sus/c1/models/c1sus.mdl further the control block we are using comes from the same path but from the c1sup.mdl model. This plant model is the bases for all of my custom plant models and thus is a good starting point for the testing. It is also ideal because I know it can beeasily altered into a my state-space plant model. However, we had to make a few adjustments to get the model up to date for the cds system. So it is now a unique block.

These two library blocks are set in the userapps/lib folder on the cymac. This is the lib file that the docker system looks to when it is compiling models. For a quick overview see this. All other models have been removed from the MatLab path so that when we open x1sus_cp.mdl in MatLab it is using the same models it will compile with.

We could not find the rtbitget library part, but chris pointed us to userapps, and we copied it over using: scp /opt/rtcds/userapps/trunk/cds/common/models/rtbitget.mdl controls@c1sim:/home/controls/simLink/lib.

NOTE TO FUTURE IAN: don't forget that unit delays exist.

Next step: now that we have a model that is compiling and familiar we need to make medm screens. We will use the auto mdl2adl for this so that it is quick. Then we can start adding our custom pieces one by one so that we know that they are working. We will also work with Raj to get an independent python model working. Which will allow us to compare the cds and python models.

Attachment 1: x1sus_cp.png
16464   Thu Nov 11 00:11:39 2021 KojiSummarySUS2" to 3" sleeve issue

Yehonathan and Tega found that the new PR3 and SR3 delivered in 2020 is in fact 3/4" in thickness (!). Digging the past email threads, it seems that the spec was 10mm but the thickness was increased for better relieving the residual stress by the coatings.

There are a few issues.

1. Simply the mirror is too thick for the ring. It sticks out from the hole. And the mirror retainers (four plastic plates) are too far from the designed surface, which will make the plates tilted.

2. The front side of the mirror assembly is too heavy and the pitch adjustment is not possible with the balance mass.

Some possible solutions:

- How about making the recess deeper?
In principle this is possible, but the machining is tricky because the recess is not a simple round hole but has "pads" where the mirror sits. And the distance of the retainer to the thread is still far.
And the lead time might become long.

- How about making new holes on the ring to shift the clamp?
Yes it is possible. This will shift the mirror assembly by a few mm. Let's consider this.

- How about modifying the wire blocks?
Yes it is equivalent to shift the holes on the ring. Let's consider this too.

1. How to hold the mirror with the retainer plates

[Attachment 1] The expected distance between the retainer plate and the threaded hole is 13.4mm. We can insert a #4-40 x L0.5" stand off (McMaster-Carr 91197A150, SUS316) there. This will make the gap down to 0.7mm. With a washer, we can handle this gap with the plate. Note that we need to use vented & silver plated #4-40 screws to hold the plates.

[Attachment 2] How does this look like when the CoM is aligned with the wire plane? Oh, no... the lower two plates will interfere with the EQ stops and the EQ stop holders. We have to remove them. [Attachment 3]
We need to check with the suspension if the EQ stop screws may hit the protruded optics and can cause chipping/cracking.

2. Modifying the wire block

[Attachment 4] The 4x thru holes of the wire block were extended to be +/-0.1" slots. The slots are too long to form ovals and produce thin areas. With the nominal position of the balance mass, the clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.19mm backside (magnet side) and 0.9134 mm lower from the wire clamping points. This looks mathematically doable, but the feasibility of the manufacturing is questionable.

[Attachment 5] Because the 0.1" shift of the CoM is large, we are able to make new #2-56 thread holes right next to the original ones. The clamp coordinates are y=1.016 (vertical) and z=-2.54mm (longitudinal).
==> The CoM is 0.188mm backside (magnet side) and 0.9136 mm lower from the wire clamping points. With the given parameters, the expected pitch resonant frequency is 0.756Hz

 My Recommendation - Modify the metal ring to shift the #2-56 threads by 0.1" - The upper two retainer plates will have #4-40 x 0.5" stand off. Use vented Ag-coated #4-40 screws. - The lower two are to be removed. - Take care of the EQ stops. - Of course, the best solution is to redesign the holder for 3/4" optics. Can we ask Protolab for rapid manufacturing???

Why did we need to place the mass forward to align the 1/4" thick optic?

We were supposed to adjust the CoM not to have too much adjustment. But we had to move the balance mass way too front for the proper alignment with a 1/4" thick optic. Why...?
This is because the ring was designed for a 3/8" thick optic... It does not make sense because the depth of the thread holes for the retainer plate was designed for 1/4" optics...

When the balance mass is located at the neutral position, the CoM coordinate is

x 0.0351mm (x+: left side at the front view)
y 0.0254mm (y+: vertical up)
z 0.4493mm (z+: towards back)

So, the CoM is way too behind. When the balance mass was stacked and the moved forward (center of the axis was moved forward by 0.27"), the CoM coordinate is (Attachment 6)

x 0.0351mm
y 0.0254mm
z 0.0011mm

This makes sens why we had to move the balance mass a lot for the adjustment.

Attachment 1: Screenshot_2021-11-11_001050.png
Attachment 2: Screenshot_2021-11-11_010405.png
Attachment 3: Screenshot_2021-11-11_010453.png
Attachment 4: Screenshot_2021-11-11_012213.png
Attachment 5: Screenshot_2021-11-11_011336.png
Attachment 6: Screenshot_2021-11-10_235100.png
16467   Tue Nov 16 11:37:26 2021 HangHowToSUSFitting suspension model--large systematic errors

One goal of our sysID study is to improve the aLIGO L2A feedforward. Our algorithm currently improves only the statistical uncertainty and assumes the systematic errors are negligible. However, I am currently baffled by how to fit a (nearly) realistic suspension model...

My test study uses the damped aLIGO QUAD suspension model. From the Matlab model I extract the L2 drive in [N] to L3 pitch in [rad] transfer function (given by a SS model with the A matrix having a shape of 103x103). I then tried to use VectFIT to fit the noiseless TF. After removing nearby z-p pairs (defined by less than 0.2 times the lowest pole frequency) and high-frequency zeros, I got a model with 6 complex pole pairs and 4 complex zero pairs (21 free parameters in total). I also tried to fit the TF (again, noiseless) with an MCMC algorithm assuming the underlying model has the same number of parameters as the VectFIT results.

Please see the first attached plots for a comparison between the fitted models and the true one. In the second plot, we show the fractional residual

| TF_true - TF_fit | / | TF_true |,

and the inverse of this number gives the saturating SNR at each frequency. I.e., when the statistical SNR is more than the saturating value, we are then limited by systematic errors in the fitting. And so far, disappointingly I can only get an SNR of 10ish for the main resonances...

I wonder if people know better ways to reduce this fitting systematic... Help is greatly appreciated!

Attachment 1: L2L_L3P_fit.pdf
Attachment 2: L2L_L3P_residual.pdf

https://dcc.ligo.org/LIGO-S2101689

https://dcc.ligo.org/LIGO-S2101690

https://dcc.ligo.org/LIGO-S2101691

https://dcc.ligo.org/LIGO-S2101692

The units are completely passive right now and has option to extend to have a dewhitening board added inside.
So the power switch does nothing.

Some of the components for the dewhitening enhancement are attached inside the units.

Attachment 1: PXL_20211211_053155009.jpg
Attachment 2: PXL_20211211_053209216.jpg
Attachment 3: PXL_20211211_050625141-1.jpg

Anything else? Feel free to edit this entry.

- SUS: AS1 hanging

- SUS: PR3/SR2/LO2 3/4" thick optic hanging

v Electronics chain check (From DAC to the end of the in-air cable / From the end of the in-air cable to the ADC)
[ELOG 16522]

- Long cable installation (4x 70ft)

- In-air cable connection to the flange

- In-vac wiring (connecting LO1 OSEMs)

- LO1 OSEM insertion/alignment

- LO1 Damping test

I had the fear that any mistake in the electronics chain could have been the show stopper.

So I quickly checked the signal assignments for the ADC and DAC chains.

I had initial confusion (see below), but it was confirmed that the electronics chains (at least for LO1) are correct.

Note: One 70ft cable is left around the 1Y0 rack

There are a few points to be fixed:

- It looks like the ADC/DAC card # assignment has been messed up.

CDS DAC0 -> Cable label DAC2 -> AI D2 -> ...
CDS DAC1 -> Cable label DAC0 -> AI D0 -> ...
CDS DAC2 -> Cable label DAC1 -> AI D1 -> ...
(What is going on here... please confirm and correct as they become straight forward)

Once this puzzle was solved I could confirm reasonable connections from the end of the 70 cables to the ADC/DAC.

My system wiring diagram needs to be fixed accordingly too.
This is because the last channel of the first ADC (ADC0) is not available for us and is used for DuoTone.

Attachment 1: PXL_20211218_030145356.MP.jpg

The I/O chassis reassigns the ADC and DAC indices on every power cycle. When we moved it, it must have changed it from the order we had. We were aware of this fact and decided to reconnect the I/O chassis to AA/AI to relect the correct order. We forgot to do that but this is not an error, it is expected behavior and can be solved easily.

The in-vacuum installation team has reported that the side OSEMs of ITMX and LO1 are going to be interfering if place LO1 at the planned location.
I confirmed that ITMX has the side magnet on the other side (Attachment 1 ITMX photo taken on 2016/7/21). So we can do this swap.

The ITMX side OSEM is sticking out most. By doing this operation, we will recover most of the space between the ITMX and LO1. (Attachment 2)

Attachment 1: ITMX_2016_07_21.jpg
Attachment 2: Screen_Shot_2021-12-22_at_18.03.42.png
16538   Sun Jan 2 20:46:46 2022 KojiUpdateSUSEnd SUS Electronics building

19:00~ Start working on the electronics bench

The following units were tested and ready to be installed. These are the last SUS electronics units and we are now ready to upgrade the end SUS electronics too.

40m End DAC Adapter Unit D2100647/ 2 Units (S2200003 S2200004)

These are placed on Tega's desk together with the vertex DAC adapters

0:30 End work

Attachment 1: PXL_20220103_081133119.jpg
16549   Thu Jan 6 15:10:38 2022 KojiUpdateSUSITMX Chamber work

[Anchal, Koji]

=== Summary ===
- ITMX SD OSEM migration done
- LO1 OSEM insertion and precise adjustment (part 1) done
- LO1 POS/PIT/YAW/SD motions were damped

=== General Remarks ===
- 15:00 Entered into ITMX.
- We were equipped with N95 and took physical distance as much as possible.
- 17:00 Temporarily came out from the lab.
- 18:30? Came into the chamber again
- 20:00 Sus damped. OSEM work continues
- 21:00 OSEM installation work done. Exit.

=== ITMX SD OSEM position swap ===
- Moved the LO1 suspension to the center of the chamber
- Removed the ITMX SD OSEM from the right side (west side) and tried to move it to the other side.
- Noted that the open light output of the ITMX SD was 908 at the output of the SDSEN filter module. So the half-light target is 454. These numbers include the "cnt2um" calibration of 0.36. That means the open light raw ADC count was supposed to be 2522.

- The OSEM set screw (silver plated, with a plunger) was removed from the old position. We first tried to recycle it to the other side, but it didn't go into the thread with fingers. After making ourselves convinced that the threaded hole was identical for both sides, we decided to put the new identical plunger set screw with an Allen-key was used to put it in and it went in!
- Now the ITMX SD OSEM was inserted from the east side. Once we saw some shadow on the OSEM signal, the SD damping was turned on with the previous setting. And this successfully damped the side motion. ⭕️
- A bit finer adjustment has been done. After a few trials, we reached the stable output of ~400. Considering the temporary leveling of the table, we decided this is enough for now ⭕️. The set screw was tightened.
- To make the further work safer w.r.t the ITMX magnets, Anchal fastened the EQ stops of the ITMX sus except for the bottom four.
- Photo: [Attachment 1]

=== LO1 OSEM installation ~ wiring ===
- Now LO1 was moved back to the planned position.
- For the wiring, we (temporarily) clamped the in-vac DSUB cables to the stack table with metal clamps.
- Started plugging the OSEMs into the DSUB cables.
- Looking at the LO1-1 cable from the mating side with the longer side top: The top-right pin of the female connector is Pin1 as usual. From right to left LL / UR / UL coils were inserted one by one while looking at the OSEM PD signals.
- LO1-2 cable has the LR / SD coils (from the right to the left) were connected.
- Photo: [Attachment 2]

- LO1 Open light levels (raw ADC counts) the 2nd number is the target half-light level

• UL 27679 (-> 13840)
• UR 29395 (-> 14697)
• LR 30514 (-> 15257)
• LL 27996 (-> 13998)
• SD 26034 (-> 13017)

=== RTS Filter implementation ===

- Anchal copied the filter module settings from other suspensions.
- We also implemented the simple input and output matrices.

=== LO1 OSEM insertion ===

- We struggled to make the suspension freely swinging with the OSEMs inserted.

- It seemed that the magnets were sucked to the OSEMs due to magnetic components.
- It turned out that the OSEMs were not fastened well and not seated in the holder plates.
- Once this was fixeded, we found that the mirror height is too high for the given OSEM heights.
The suspension height (or the OSEM height should be decided with the OSEMs not inserted but fully fastened to prevent misalignment of them.

- Decided to lift up the OSEM plates in situ.
- Soon we found that the OSEM holder plates are not fastened at all [Attachment 3 arrows]
- The plates were successfully lifted up and
the suspension became much more freely swinging even with the OSEMs inserted. ⭕️

=== LO1 damping and more precise OSEM insertion ===

- Once the OSEMs were inserted to the light level of 30~70%, we started to try to dampen the motion. The side damping was somewhat successful, but the face ones were not.
- We checked the filters and found the coil output filters didn't have the alternating signs.
- Once the coil signs were corrected, the damping became more straight forward.
- And the robust damping allowed us the fine-tuning of the OSEM insertion.

- In the end, what we had for the light levels were

• UL 14379 (52%)
• UR 14214 (48%)
• LR 14212 (47%)
• LL 12869 (46%)
• SD 14358 (55%)

The damping is working well. [Attachment 4]

Post continues at 40m/16552.

Attachment 1: PXL_20220107_044739280.MP.jpg
Attachment 2: PXL_20220107_044958224.jpg
Attachment 3: PXL_20220107_044805503.NIGHT.jpg
Attachment 4: Screen_Shot_2022-01-06_at_20.54.04.png
16571   Tue Jan 11 10:58:58 2022 TegaUpdateSUSTemporary watchdog

Started working on this. First created a git repo for tracking https://git.ligo.org/40m/susaux.git

I have looked through the folder to see what needs doing and I think I know what needs to be done for the final case by just following the same pattern for the other optics, which I am listing below

- Create database file for the BHD optics, say C1_SUS-AUX_LO1.db by copying another optic database file say C1_SUS-AUX_SRM. Then replace the optic name.

- Insert a new line "C1:SUS-LO1_LATCH_OFF" in the file autoBurt_watchdogs.req

- Populate the file autoBurt.req with the appropriate channels for LO1

- Populate the file C1SUSaux_post.sh with the corresponding commands for LO1

For the temporary watchdog, we comment everything I have just talked about, and do only what come next.

My question is the following:

I understand that we need to use the OUT16 slow channel as a temporary watchdog since we don't currently have access to the slow channels bcos the Acromag units have not been installed. My guess from Koji's instructions is that we need to update the channels in the last two fields "INPA" and "INPB" below

record(calc,"C1:SUS-LO1_UL_CALC")
{
field(DESC,"ANDs Enable with Watchdog")
field(SCAN,"1 second")
field(PHAS,"1")
field(PREC,"2")
field(HOPR,"40")
field(LOPR,"-40")
field(CALC,"A&B")
field(INPA,"C1:SUS-LO1_UL_COMM  PP  NMS")
field(INPB,"C1:SUS-LO1_LATCH_OFF  PP  MS")
}

Suppose we replace the channel for INPA with C1:SUS-LO1_ULCOIL_OUT16, what about INPB. Is this even the right thing to do as I am just guessing here?

16573   Tue Jan 11 13:43:14 2022 KojiUpdateSUSTemporary watchdog

I don't remember the syntax of the db file, but here this calc channel computes A&B. And A&B corresponds to INPA and INPB.

        field(CALC,"A&B")         field(INPA,"C1:SUS-LO1_UL_COMM  PP  NMS")         field(INPB,"C1:SUS-LO1_LATCH_OFF  PP  MS")`

What is this LATCH doing?

16600   Wed Jan 19 21:39:22 2022 TegaUpdateSUSTemporary watchdog

After some work on the reference database file, we now have a template for temporary watchdog implementation for LO1 located here "/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db".

Basically, what I have done is swap the EPICS asyn analog input readout for the COIL and OSEM to accessible medm channels, then write out watchdog enable/disable to coil filter SW2 switch. Everything else in the file remains the same. I am worried about some of the conversions but the only way to know more is to see the output on the medm screen.

To test, I restarted c1su2 but this did not make the LO1 database available, so I am guessing that we also need to restart the c1sus, which can be done tomorrow.

16601   Thu Jan 20 00:26:50 2022 KojiUpdateSUSTemporary watchdog

As the new db is made for c1susaux, 1) it needs to be configured to be read by c1susaux 2) it requires restarting c1susaux 3) it needs to be recorded by FB 4) and restartinbg FB.
(^-Maybe not super exact procedure but conceptually like this)

16606   Thu Jan 20 17:21:21 2022 TegaUpdateSUSTemporary watchdog

Temp software watchdog now operational for LO1 and the remaining optics!

Koji helped me understand how to write to switches and we tried for a while to only turnoff the output switch of the filters instead of the writing a zero that resets everything in the filter.

Eventually, I was able to move this effort foward by realising that I can pass the control trigger along multiple records using the forwarding option 'FLNK'. When I added this field to the trigger block, record(dfanout,"C1:SUS-LO1_PUSH_ALL"), and subsequent calculation blocks, record(calcout,"C1:SUS-LO1_COILSWa") to record(calcout,"C1:SUS-LO1_COILSWd"), everything started working right.

 Quote: After some work on the reference database file, we now have a template for temporary watchdog implementation for LO1 located here "/cvs/cds/caltech/target/c1susaux/C1_SUS-AUX_LO1.db". Basically, what I have done is swap the EPICS asyn analog input readout for the COIL and OSEM to accessible medm channels, then write out watchdog enable/disable to coil filter SW2 switch. Everything else in the file remains the same. I am worried about some of the conversions but the only way to know more is to see the output on the medm screen. To test, I restarted c1su2 but this did not make the LO1 database available, so I am guessing that we also need to restart the c1sus, which can be done tomorrow.

16675   Tue Feb 22 18:47:51 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement

[Ian, Koji]

In preparation for the replacement of the suspension electronics that control the ETMY, I took measurments of the system excluding the CDS System. I took transfer functions from the input to the coil drivers to the output of the OSEMs for each sensor: UL, UR, LL, LR,  and SIDE. These graphs are shown below as well as all data in the compressed file.

We also had to replace the oplev laser power supply down the y-arm. The previous one was not turning on. the leading theory is that it's failure was caused by the power outage. We replaced it with one Koji brought from the fiber display setup.

I also am noting the values for the OSEM DC output

 OSEM Value UL 557 UR 568 LR 780 LL 385 SIDE 328

In addition the oplev position was:

 OPLEV_POUT 4.871 OPLEV_YOUT -0.659 OPLEV_PERROR -16.055 OPLEV_YERROR -6.667

(KA ed) We only care about PERROR and YERROR (because P/YOUT are servo output)

Edit: corrected DC Output values

Attachment 1: ALL_TF_Graph.pdf
Attachment 2: 20220222_SUSElectronicsReplacement.7z
16680   Fri Feb 25 14:00:08 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement

[Koji, Ian]

We looked at a few power supplies and we found one that was marked "CHECK IF THIS WORKS" in yellow. We found that the power supply worked but the indicator light didn't work. I tried a two other lights from other power supplies that did not work but they did not work. Koji ordered a new one.

Attachment 1: IMG_0853.jpg
Attachment 2: IMG_0852.jpg
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