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ID Date Author Type Category Subjectdown
  2255   Thu Nov 12 15:40:27 2009 josephb, koji, peterUpdateComputersETMY and Megatron test take 1

We connected megatron to the IO chassis which in turn was plugged into the rest of the ITMY setup.  We had manually turned the watchdogs off before we touched anything, to ensure we didn't accidently drive the optic.  The connections seem to go smoothly.

However, on reboot of megatron with the IO chassis powered up, we were unable to actually start the code.  (The subsystem has been renamed from SAS to TST, short for test).  While starttst claimed to start the IOC Server, we couldn't find the process running, nor did the medm screens associated with it work.

As a sanity test, we tried running mdp, Peter's plant model, but even that didn't actually run.  Although it also gave an odd error we hadn't seen before:

"epicsThreadOnceOsd epicsMutexLock failed."

Running startmdp a second time didn't give the error message, but still no running code.  The mdp medm screens remained white.

We turned the IO chassis off and rebooted megatron, but we're still having the same problem.

 

Things to try tomorrow:

1) Try disconnecting megatron completely from the IO chassis and get it to a state identical to that of last night, when the mdp and mdc did run.

2) Confirm the .mdl files are still valid, and try rebuilding them

  14551   Thu Apr 18 22:35:23 2019 gautamUpdateSUSETMY actuator diagnosis

[rana, gautam]

Rana did a checkout of my story about oddness of the ETMY suspension. Today, we focused on the actuators - the goal was to find the correct coefficients on the 4 face coils that would result in diagonal actuation (i.e. if we actuate on PIT, it only truly moves the PIT DoF, as witnessed by the Oplev, and so on for the other DoFs). Here are the details:

  1. Ramp times for filter modules:
    • All the filter modules in the output matrix did not have ramp times set.
    • We used python, cdsutils and ezca to script the writing of a 3 second ramp to all the elements of the 5x6 output matrix.
    • The script lives at /opt/rtcds/caltech/c1/scripts/cds/addRampTimes.py, can be used to implement similar scripts to initialize large numbers of channels (limiters, ramp times etc).
  2. Bounce mode checkout:
    • ​The motivation here was to check if there is anomalously large coupling of the bounce mode to any of the other DoFs for ETMY relative to the other optics
    • The ITMs have a different (~15.9 Hz) bounce mode frequency compared to the ETMs (~16.2 Hz).
    • I hypothesize that this is because the ETMs were re-suspended in 2016 using new suspension wire.
    • We should check out specs of the wires, look for either thickness differences or alloying composition variation (Steve has already documented some of this in the elog linked above). Possibly also check out the bounce mode for a 250g load on the table top.
  3. Step responses for PIT and YAW
    • With the Oplevs disabled (but other local damping loops engaged), we applied a step of 100 DAC counts to the PIT and YAW DoFs from the realtime system (one at a time)
    • We saw significant cross-coupling of the YAW step coupling to PIT, at the level of 50%.
  4. OSEM coil coefficient balancing
    • I had done this a couple of months ago looking at the DC gain of the 1/f^2 pendulum response.
    • Rana suggested an alternate methodology 
      • we used the lock-in amplifier infrastructure on the SUS screens to drive a sine wave
      • Frequencies were chosen to be ~10.5 Hz and ~13.5 Hz, to be outside the Oplev loop bandwidth
      • Tests were done with the Oplev loop engaged. The Oplev error signal was used as a diagnostic to investigate the PIT/YAW cross coupling.
      • In the initial tests, we saw coupling at the 20% level. If the Oplev head is rotated by 0.05 rad relative to the "true" horizontal-vertical coordinate system, we'd expect 5% cross coupling. So this was already a red flag (i.e. it is hard to believe that Oplev QPD shenanigans are responsible for our observations). We decided to re-diagonalize the actuation.
      • The output matrix elements for the lock-in-amplifier oscillator signals were adjusted by adding some amount of YAW to the PIT elements (script lives at /opt/rtcds/caltech/c1/scripts/SUS/stepOutMat.py), and vice versa, and we tried to reduce the height of the cross-coupled peaks (viewed on DTT using exponential weighting, 4 avgs, 0.1 Hz BW - note that the DTT cursor menu has a peak find option!). DTT Template saved at /users/Templates/SUS/ETMY-actDiag.xml
      • This worked really well for minimizing PIT response while driving YAW, not as well for minimizing YAW in PIT. 
      • Next, we added some YAW to a POS drive to minimize the any signal at this drive frequency in the Oplev YAW error signal. Once that was done, we minimized the peak in the Oplev PIT error signal by adding some amount of PIT actuation.
      • So we now have matrices that minimize the cross coupling between these DoFs - the idea is to back out the actuation coefficients for the 4 OSEM coils that gives us the most diagonal actuation, at least at AC. 
  5. Next steps:
    • All of our tests tonight were at AC - once the coil balancing has been done at AC, we have to check the cross coupling at DC. If everything is working correctly, the response should also be fairly well decoupled at DC, but if not, we have to come up with a hypothesis as to why the AC and DC responses are different.
    • Can we gain any additional info from driving the pringle mode and minimizing it in the Oplev error signals? Or is the problem overconstrained?
    • After the output matrix diagonalization is done, drive the optic in POS, PIT and YAW, and construct the input matrix this way (i.e. transfer function), as an alternative to the usual free-swinging ringdown method. Look at what kind of an input matrix we get.
    • Repeat the free-swinging ringdown with the ETMY bias voltage adjusted such that all the OSEM PDmons report ~100 um different position from the "nominal" position (i.e. when the Y arm cavity is aligned). Investigate whether the resulting eigenmode frequencies / Qs are radically different. I'm setting the optic free-swinging on my way out tonight. Optic kicked at 1239690286.
  2204   Sun Nov 8 14:18:25 2009 AlbertoUpdateSUSETMY Watchdogs tripped

This afternoon I re-enabled the ETMY coils after I found that the watchdogs for the mirror had tripped last night at 2:06am.

  242   Wed Jan 16 18:24:41 2008 ranaUpdateSUSETMY Watchdog
Because Steve keeps complaining about ETMY, I looked at some minute trend to see if there was something exotic happening at that time. It looks like there is some tremendous seismic activity to make it happen.

The trend shows that there is nothing special happening on the ETMX accelerometer or the ETMX suspension. At the same time, however, there is a huge jump in the ETMY sensors and therefore the watchdog signal. Whenever the watchdog value goes above 140, it trips.

After Andrey moves some accelerometers over to the Y end we can see the effect more directly.
Attachment 1: A.pdf
A.pdf
  12445   Fri Aug 26 11:35:44 2016 gautamUpdateSUSETMY UL sensor problematic

I've been noticing that the ETMY UL sensor output has been erratic  over the last few days. It seems to be jumping around a lot, even though there is no discernable change in any of the other sensor signals. Damping is OFF, which means the sensor signals should just be a reflection of actual test mass motion. But the fact that only one sensor output is erratic leads me to believe that the problem is in the electronics. I've also double checked that we aren't touching any EQ stops. Also, we had centered all the sensor outputs to half their maximum value pretty carefully. But looking at the Striptool traces, I now find that the UL sensor output has settled at some other value. Simply removing the OSEM connector and plugging it in again leads to the sensor output going back to the carefully centered value. Could it be that the photodiode has gone bad? If so, do we have spare OSEMs to use? I will also re-squish the satellite box cables to see if that fixes the problem.

Attachments:

Attachment #1: Sensor output spectra around the bounce mode peak. Nothing was touched inside the chamber between the time this spectrum was taken and the spectrum I put up last night (in fact the chamber was closed)

Attachment #2: UL sensor output is erratic, while the others show no glitching. This supports the hypothesis that the problem is electronic. The glitch itself happened while the chamber was closed.

Attachment #3: The only difference between this trace and Attachment #2 is that the UL connector was removed and plugged in (OSEM wasn't touched)

Attachment 1: ETMY_BounceSpectra_26Aug2016.pdf
ETMY_BounceSpectra_26Aug2016.pdf
Attachment 2: 41.png
41.png
Attachment 3: 19.png
19.png
  12446   Fri Aug 26 14:05:38 2016 SteveUpdateSUSETMY UL sensor problematic

This problem has existed well before the vent

 

Attachment 1: ETMY-ULhistory.png
ETMY-ULhistory.png
  12447   Fri Aug 26 14:09:46 2016 ericqUpdateSUSETMY UL sensor problematic

We do indeed have a box of clean spare OSEMs, it should be out with all of the other boxes of clean stuff we had for the suspension building. You could also try swapping in a different satellite box, to see if the circuit powering the OSEM PD is to blame.

  12449   Sun Aug 28 21:40:11 2016 gautamUpdateSUSETMY UL sensor problematic

I wanted to observe the UL coil for any excursions over the weekend. Looking at the 2 day trend, something is definitely wrong. These glitches/excursions are much more pronounced than what is seen in the pre-vent plots Steve had put up.

In order to try and narrow down whether the problem is with the Satellite box or the LED/PD themselves, I switched the Satellite box at the Y end with the Satellite box for ITMY (at ~930pm tonight). Hopefully over a 12 hour observation period, we see something that will allow us to make some conclusion. 

Attachment 1: ETMY_UL_problematic.png
ETMY_UL_problematic.png
  12450   Mon Aug 29 09:37:05 2016 gautamUpdateSUSETMY UL sensor problematic

It looks like the problem is indeed in the Satellite box. Attachment #1 shows the second trend for the last 12 hours (~930pm 28 Aug 2016 - 930am 29 Aug 2016) for the ITMY and ETMY sensor signals. The satellite boxes for the two were switched during this time (the switch is seen at the leftmost edge of the plots). After the switch, ETMY UL has been well behaved, though ITMY UL shows evidence of excursions similar to what we have been seeing. All the ITMY coils are pulled out of the suspension cage currently, and are just sitting on the optical table, so they should just be reading out a constant value. I think this is conclusive evidence that the problem is with the Satellite box and not the OSEM itself. I will pull the Satellite box out and have a look at its innards to see if I can find the origin of the problem...

Attachment 1: satelliteBox.png
satelliteBox.png
  12350   Thu Jul 28 22:43:03 2016 ranaUpdateGeneralETMY UL magnet broke off

I'd recommend replacing the wire and grinding down the clamp to prevent cutting the wire. Since we have almost never replaced clamps, many of them probably have grooves from the wires and can make unpleasant cuts. Better safe than sorry in this case.

  12486   Tue Sep 13 11:00:59 2016 LydiaUpdateSUSETMY UL glitch returned

 

Quote:

For the ITMY, I squished together the cables which are in the 'Cable Interface Board' which lives in the rack. This thing takes the 64 pin IDC from the satellite module and converts it into 2 D-sub connectors to go to the PD whitening board and the coil driver board. Lets see if the ITMY OSEM glitches change character overnight.

Last night from 8:30 pm to 8:30 am PDT, ETMY UL signal was glitchy again. As of now it seems to have quieted back down, but we pushed on the cables on the board at the Y end to hopefully prevent it from coming back. After doing so it still seems to be behaving well.

  2287   Tue Nov 17 21:21:30 2009 robUpdateSUSETMY UL OSEM

Had been disconnected for about two weeks.  I found a partially seated 4-pin LEMO cable coming from the OSEM PD interface board. 

  367   Mon Mar 10 20:46:41 2008 JohnConfigurationLSCETMY Trans PD & QPD
I've placed a 10% reflector in the path from ETMY to the trans and quadrant photodiodes.
  13101   Sat Jul 8 17:09:50 2017 gautamUpdateGeneralETMY TRANS QPD anomaly

About 2 weeks ago, I noticed some odd behaviour of the LSC TRY data stream. Its DC value seems to be drifting ~10x more than TRX. Both signals come from the transmission QPDs. At the time, we were dealing with various CDS FE issues but things have been stable on that end for the last two weeks, so I looked into this a bit more today. It seems like one particular channel is bad - Quadrant 4 of the ETMY TRANS QPD. Furthermore, there is a bump around 150Hz, and some features above 2kHz, that are only present for the ETMY channels and not the ETMX ones.

Since these spectra were taken with the PSL shutter closed and all the lab room lights off, it would suggest something is wrong in the electronics - to be investigated.

The drift in TRY can be as large as 0.3 (with 1.0 being the transmitted power in the single arm lock). This seems unusually large, indeed we trigger the arm LSC loops when TRY > 0.3. Attachment #2 shows the second trend of the TRX and TRY 16Hz EPICS channels for 1 day. In the last 12 hours or so, I had left the LSC master switch OFF, but the large drift of the DC value of TRY is clearly visible.

In the short term, we can use the high-gain THORLABS PD for TRY monitoring.

Attachment 1: ETMY_QPD.pdf
ETMY_QPD.pdf
Attachment 2: ETMY_QPD.png
ETMY_QPD.png
  13102   Sun Jul 9 08:58:07 2017 ranaUpdateGeneralETMY TRANS QPD anomaly

Indeed, the whole point of the high/low gain setup is to never use the QPDs for the single arm work. Only use the high gain Thorlabs PD and then the switchover code uses the QPD once the arm powers are >5.

I don't know how the operation procedure went so higgledy piggledy.

  4408   Sun Mar 13 04:00:53 2011 ranaUpdateCDSETMY Sim work

I did some work on the ETMY real and Sim.

  1. Set SUS coil gains to have the same quadropole arrangement as the magnets do (-1, 1, 1, -1) so that POS = POS instead of pringle.
  2. Set the Sim Magnet polarities to match this. These are the ETMY_CI filter banks.
  3. Found that the Xycom cable from the ETMY slow controls was unplugged at the Xycom side. This was preventing enabling the ETMY coil driver and so there was no real damping of the suspension going on. I plugged it in and checked that the mirror could now be moved.
  4. The C1SUS_ETMY master screen's BLUE output filter area is now mis-labeled. If you trust the screen you would set it up to drive the suspension incorrectly. This MUST be fixed along with all of the other misleading features of the screen.
  5. ETMY SUSSIDE filter bank had a 2048 Hz sample rate and was making the damping not work correctly. Fixed to 16384 Hz.
  6. 12 Hz, 4th order Cheby low pass added and turned on for the local damping filtering. This is not optimum, but its just there to give us some filtering without introducing some instability via phase lag around 3 Hz.
  7. ETMY OL beam re-aligned on ISCT-EX.
  8. TM Offset buttons not working on the main overview screen.

It seems like there is still a problem with the input whitening filters. I believe the Xycom logic is set such that the analog whitening of the OSEM signals is turned ON only when the FM1 is turned OFF. Joe has got to fix this (and elog it) so that we can damp the suspension correctly. For now, the damping of the ETMY and the SETMY require different servo gains and signs, probably because of this.

  4409   Sun Mar 13 16:46:48 2011 josephbUpdateCDSETMY Sim work

4. The blue Output Filters  section has been changed to agree with the new filter of matrices row, column labeling.  My fault for not testing it and realizing it was broken.  The change was made in /opt/rtcds/caltech/c1/medm/master/C1SUS_DEFAULTNAME.adl and then ,/generate_master_screens.py was run, updating all the screens.

5.  I have swapped the logic for the sensor filter banks (ULSEN, URSEN, etc).  It now sends a "1" to the Binary Output board controlling the OSEM analog whitening when the FM1 filter is ON.  This has been done for all the suspensions (BS, ITMX,ITMY, SRM, PRM, MC1, MC2,MC3, ITMX, ITMY).

I am also updating the first sensor filter banks for the BS, ITMX, ITMY, SRM, PRM,MC1,MC2,MC3, called "3:30", to match the Y and X ends.

8.  I can't find any documentation on how to get a momentary button press to toggle states.  I could stick a filter bank in and use the on/off feature of that part, but that feels like a silly hack.  I've decided for the moment to split the TM offset button into 2, one for ON, one for OFF.  I'll put in on the list of things to have added to the RCG code (either a method, or documentation if it already exists). 

EDIT:  TM offset still doesn't work.  Will worry about it next week.

9.  Fixed a connection in SPY/SPX models where  the side senor path that was missing a constant to a modulo block.

Quote:

I did some work on the ETMY real and Sim.

  1. Set SUS coil gains to have the same quadropole arrangement as the magnets do (-1, 1, 1, -1) so that POS = POS instead of pringle.
  2. Set the Sim Magnet polarities to match this. These are the ETMY_CI filter banks.
  3. Found that the Xycom cable from the ETMY slow controls was unplugged at the Xycom side. This was preventing enabling the ETMY coil driver and so there was no real damping of the suspension going on. I plugged it in and checked that the mirror could now be moved.
  4. The C1SUS_ETMY master screen's BLUE output filter area is now mis-labeled. If you trust the screen you would set it up to drive the suspension incorrectly. This MUST be fixed along with all of the other misleading features of the screen.
  5. ETMY SUSSIDE filter bank had a 2048 Hz sample rate and was making the damping not work correctly. Fixed to 16384 Hz.
  6. 12 Hz, 4th order Cheby low pass added and turned on for the local damping filtering. This is not optimum, but its just there to give us some filtering without introducing some instability via phase lag around 3 Hz.
  7. ETMY OL beam re-aligned on ISCT-EX.
  8. TM Offset buttons not working on the main overview screen.

It seems like there is still a problem with the input whitening filters. I believe the Xycom logic is set such that the analog whitening of the OSEM signals is turned ON only when the FM1 is turned OFF. Joe has got to fix this (and elog it) so that we can damp the suspension correctly. For now, the damping of the ETMY and the SETMY require different servo gains and signs, probably because of this.

 

  12451   Mon Aug 29 14:42:06 2016 gautamUpdateSUSETMY Satellite box diagnostics

I opened up the ETMY satellite box to investigate the glitches seen in the UL sensor output. 

Attachments #1 & 2: The connection to J4 from the satellite amplifier goes through a "satellite amplifier termination board", whose function, according to the schematic, is to prevent oscillations of the output amplifiers for the PD outputs. This seems to have been attached to the inside cover of the Satellite box by means of some sort of sponge/adhesive arrangement. The box itself gets rather hot however, and the sponge/adhesive was a gooey mess. I believe it is possible that some pins on the termination board were getting shorted - so if the 100 ohm resistor for the Ul channel that is meant to prevent the output amplifier oscillating was getting shorted, this could explain the problem.

For now, I cleaned off the old sponge/adhesive as best as I could, and used 4 pads of thick double sided tape (with measured resistance > 60Mohm) to affix the termination board to the inside of the box lid. In the ~3 hours since I have plugged the satellite box back in, there has been no evidence of any glitching. 

Of course, it could be that the problem has nothing to do with the termination board, and perhaps an OpAmp in the UL signal chain is damaged, but I stopped short of replacing these for now. I plan to push on with putting the IFO back together, and will keep an eye on this problem to see if more action is needed.

Also, if the inside of the ETMY satellite box had this problem of the sponge/adhesive giving way, it may be that something similar is going on in the other boxes as well. This remains to be investigated.

Attachment 1: IMG_6840.JPG
IMG_6840.JPG
Attachment 2: IMG_6841.JPG
IMG_6841.JPG
  5294   Wed Aug 24 09:11:19 2011 jamieUpdateSUSETMY SUS update: looks good. WE'RE READY TO CLOSE

We ran one more free swing test on ETMY last night, after the last bit of tweaking on the SIDE OSEM.  It now looks pretty good:

ETMY ETMY.png       pit     yaw     pos     side    butt
UL   -0.323   1.274   1.459  -0.019   0.932 
UR    1.013  -0.726   1.410  -0.050  -1.099 
LR   -0.664  -1.353   0.541  -0.036   0.750 
LL   -2.000   0.647   0.590  -0.004  -1.219 
SD    0.021  -0.035   1.174   1.000   0.137 
4.23371

 So I declare: WE'RE NOW READY TO CLOSE UP.

  16743   Fri Mar 25 11:39:14 2022 AnchalUpdateSUSETMY SUS Electronics Replacement - Questions

After Ian updated the cts2um filters for OSEM, shouldn't the damping gains be increased back by factor of 10 to previos values? Was the damping gain for SIDE ever changed? we found it at 250.

Can you explain why gain_offset filter was required and why this wasn't done for the side coil?

Quote:

I updated the gain of the ct2um filter on the OSEMS for ETMY and decreased their gain by a factor of 9 from 0.36 to 0.04.

I added a filter called "gain_offset" to all the coils except for side and added a gain of 0.48.

together these should negate the added gain from the electronics replacement of the ETMY

 

  16746   Mon Mar 28 16:25:34 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement - Questions

The point of changing the gains was to return the system to its origional state. ie I wanted the over all gain of the physical components to be the same as when we started. From the CDS side of things nothing else should be changed. The damping filters should remain at their origional values. The cts2um filter was changed to counteract a change in the electronics (replacing them). These changes should cancel eachother out. As for the side control, on 3/4/22 koji reduced the output resistors for the 4 face OSEMs but did not change the the SD one. there fore the SD did not need the same adjustment as the others.

Quote:

After Ian updated the cts2um filters for OSEM, shouldn't the damping gains be increased back by factor of 10 to previos values? Was the damping gain for SIDE ever changed? we found it at 250.

Can you explain why gain_offset filter was required and why this wasn't done for the side coil?

Quote:

I updated the gain of the ct2um filter on the OSEMS for ETMY and decreased their gain by a factor of 9 from 0.36 to 0.04.

I added a filter called "gain_offset" to all the coils except for side and added a gain of 0.48.

together these should negate the added gain from the electronics replacement of the ETMY

 

 

  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
ALL_TF_Graph.pdf ALL_TF_Graph.pdf ALL_TF_Graph.pdf ALL_TF_Graph.pdf 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
IMG_0853.jpg
Attachment 2: IMG_0852.jpg
IMG_0852.jpg
  16681   Fri Feb 25 14:48:53 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement

I moved the network-enabled power strip from above the power supplies on rack 1y4 to below. Nothing was powered through the strip when I unplugged everything and I connected everything to the same port after.

Attachment 1: Before.jpg
Before.jpg
Attachment 2: After.jpg
After.jpg
  16684   Sat Feb 26 23:48:14 2022 KojiUpdateSUSETMY SUS Electronics Replacement

[Ian, Koji] - Activity on 25th (Fri)

We continued working on the ETMY electronics replacement.

- The units were fixed on the rack along with the rack plan.

- Unnecessary Eurocard modules were removed from the crate.

- Unnecessary IDC cables and the sat amp were removed from the wiring chain. The side cross-connects became obsolete and they also were removed.

- A 18V DC power strip was attached to one of the side DIN rails.

Warning:

- Right now the ETMY suspension is free and not damped. We are relying on the EQ stops.

Next things to do:

- Layout the coil driving cables from the vacuum feedthru to the sat amp (2x D2100675-01 30ft ) [40m wiki]

- Layout DB cables between the units

- Layout the DC power cables from the power strip to the units

- Reassign ADC/DAC channels in the iscey model.

- Recover the optic damping

- Measure the change of the PD gains and the actuator gains.

Attachment 1: PXL_20220226_023111179_2.jpg
PXL_20220226_023111179_2.jpg
  16690   Tue Mar 1 19:26:24 2022 KojiUpdateSUSETMY SUS Electronics Replacement

The replacement key switches and Ne Indicators came in. They were replaced and work fine now.

The power supply units were tested with the X end HeNe display. It turned out that one unit has the supply module for 1350V 4.9mA while the other two do 1700V 4.9mA.
In any case, these two ignited the HeNe Laser (1103P spec 1700V 4.9mA).

The 1350V one is left at the HeNe display and the others were stored in the cabinet together with spare key SWs and Ne lamps.

Attachment 1: PXL_20220302_025723651.jpg
PXL_20220302_025723651.jpg
Attachment 2: PXL_20220302_030102033.MP.jpg
PXL_20220302_030102033.MP.jpg
  16709   Mon Mar 7 16:44:15 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement

Now that the ETMSUS is back up and running I reran my measurements from the beginning of the process. The results below show a change in gain between the before and after measurements. I have given values of the low-frequency section below.

Average Gain difference from the TFs: 18.867  (excluding thee side change)

  Before After Gain difference
UL -31 dB -5 dB 19.952
UR -36 dB -10 dB 19.952
LR -27 dB -2 dB 17.782
LL -37 dB -12 dB 17.782
SIDE -48 dB -45 dB 1.412

I also am noting the new values for the OSEM DC output: average gain increase: 9.004

OSEM DC OFFSET Before DC OFFSET After Gain increase
UL 557 5120 9.19
UR 568 5111 8.99
LR 780 7041 9.02
LL 385 3430 8.91
SD 328 2922 8.91

In addition, the oplev position was:

  Before After
 OPLEV_PERROR -16.055 -16.715
 OPLEV_YERROR -6.667 -16.597

All data and settings have been included in the zip file

From the average gain increase of the TFs which indicates the increase of the whole system and the increase in gain from the OSEM we can calculate the gain from the actuators.

18.867/9.004 = 2.09

thus the increase in gain on the actuator is about 2.09

EDIT: I updated the side TF with one with better SNR. I increased the excitation amplitude.

Attachment 1: UR_TF_Graph.pdf
UR_TF_Graph.pdf
Attachment 2: UL_TF_Graph.pdf
UL_TF_Graph.pdf
Attachment 3: LR_TF_Graph.pdf
LR_TF_Graph.pdf
Attachment 4: LL_TF_Graph.pdf
LL_TF_Graph.pdf
Attachment 5: SD_TF_Graph.pdf
SD_TF_Graph.pdf
Attachment 6: 20220307_SUSElectronicsAfterTests.zip
  16723   Fri Mar 11 16:43:03 2022 Ian MacMillanUpdateSUSETMY SUS Electronics Replacement

I updated the gain of the ct2um filter on the OSEMS for ETMY and decreased their gain by a factor of 9 from 0.36 to 0.04.

I added a filter called "gain_offset" to all the coils except for side and added a gain of 0.48.

together these should negate the added gain from the electronics replacement of the ETMY

  16233   Thu Jul 1 10:34:51 2021 Paco, AnchalSummaryLSCETMY QPD fixed

Paco worked on alignign the beam splitter to get light on the ETMY QPD and was successful in centering it without any other changes in the settings.

  13063   Wed Jun 14 18:15:06 2017 gautamUpdateASSETMY Oplev restored

I replaced the Pentek Generic Whitening Board and the Optical Lever PD Interface Board (D010033) which I had pulled out. The ETMY optical lever servo is operational again. I will post a more detailed elog with deviations from schematics + photos + noise and TF measurements shortly.

Quote:

As part of my Oplev servo investigations, I have pulled out the Pentek Generic Whitening board (D020432) from the Y-end electronics rack. ETMY watchdog was shutdown for this, I will restore it once the Oplev is re-installed.

 

  13064   Thu Jun 15 01:56:50 2017 gautamUpdateASSETMY Oplev restored

Summary:

I tried playing around with the Oplev loop shape on ITMY, in order to see if I could successfully engage the Coil Driver whitening. Unfortunately, I had no success tonight.

Details:

I was trying to guess a loop shape that would work - I guess this will need some more careful thought about loop shape optimization. I was basically trying to keep all the existing filters, and modify the low-passing that minimizes control noise injection. By adding a 4th order elliptic low pass with corner at 50Hz and stopband attenuation of 60dB yielded a stable loop with upper UGF of ~6Hz and ~25deg of phase margin (which is on the low side). But I was able to successfully engage this loop, and as seen in Attachment #1, the noise performance above 50Hz is vastly improved. But it also seems that there is some injection of noise around 6Hz. In any case, as soon as I tried to engage the dewhitening, the DAC output quickly saturated. The whitening filter for the ITMs has ~40dB of gain at ~40Hz already, so it looks like the high frequency roll-off has to be more severe.

I am not even sure if the Elliptic filter is the right choice here - it does have the steepest roll off for a given filter order, but I need to look up how to achieve good roll off without compromising on the phase margin of the overall loop. I am going to try and do the optimization in a more systematic way, and perhaps play around with some of the other filters' poles and zeros as well to get a stable controller that minimizes control noise injection everywhere.

Attachment 1: ITMY_OLspec.pdf
ITMY_OLspec.pdf
  11526   Mon Aug 24 16:10:07 2015 ericqUpdateSUSETMY Oplev laser power is falling

Today I noticed the box around the ETMY oplev sum flashing red, as it dipped below 1k. I don't recall seeing this recently, so I wanted to look up the history.

However, we've been having trouble with our minute (and longer) trend data, so I had to hack it out a bit... Here is the unfortunate result:

I think we can be fairly confident that this is not due to alignment drifts, we generally keep the QPD reasonably well centered. I also recentered it today, and the counts remained at ~1k. 


Details of the hack that got me this data:

I ended up looking at the BURT snapshots from every night at midnight, which report a number for ETMY_OL_SUM_OUT16, and making a text file with dates and values with the following BASH spaghetti:

find /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2015 -wholename "*00*/*scy*" |xargs ack --nogroup "ETMY_OL_SUM_OUT16 1" |  sed -e 's/.*2015/2015/g' -e 's/\/c1.*\([0-9]\..*$\)/, \1/g' -e 's/\//-/g'  > ETMYsum.txt

This produces a file full of unsorted lines like: 2015-Aug-23-00:07, 1.106459228515625e+03

The python package pandas is good at parsing dates and automatically plotting time series: 

olsum = pandas.read_csv('ETMYsum.txt', index_col=0, parse_dates=True)
olsum.plot()
Attachment 1: ETMYsum_trend.pdf
ETMYsum_trend.pdf
  11527   Mon Aug 24 16:46:49 2015 ericqUpdateSUSETMY Oplev laser power is falling

Repeated for all optics, ETMY seems like the only one sharply dropping for now (PRM is all over the place and hard to gauge, since we often leave it partially- or mis-aligned):

 


Hacky bits:

Bash:

find /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2015 -wholename "*00:0*"
| xargs ack --nogroup "OL_SUM_OUT16 1"
| grep -v 'SUS-MC'
| sed -e 's/.*2015/2015/g' -e 's/\/c1.*C1:SUS-/, /g' -e 's/_OL.*\([0-9]\..*$\)/, \1/g' -e 's/\//-/g'
| sort | uniq > allOL.txt

qontrols@pianosa|~ > head allOL.txt 
2015-Apr-10-00:07, BS, 1.146766113281250e+03
2015-Apr-10-00:07, ETMX, 1.597261328125000e+04
2015-Apr-10-00:07, ETMY, 4.331762207031250e+03
2015-Apr-10-00:07, ITMX, 6.488521484375000e+03
2015-Apr-10-00:07, ITMY, 1.387590234375000e+04
2015-Apr-10-00:07, PRM, 8.352053833007812e+02
2015-Apr-10-00:07, SRM, 6.099560928344727e+01
2015-Apr-1-00:07, BS, 1.180478149414062e+03
2015-Apr-1-00:07, ETMX, 1.584842480468750e+04

Python:

 

olsum = pd.read_csv('allOL.txt',parse_dates=True, names=['Date','Optic','Sum'])
olsum['Date'] = pd.to_datetime(olsum['Date']) # Automatic parsing didn't work for some reason
olpivot = olsum.pivot(index='Date',columns='Optic',values='Sum')
olpivot.plot()
Attachment 1: OLsum_trend.pdf
OLsum_trend.pdf
  11566   Thu Sep 3 08:53:55 2015 SteveUpdateSUSETMY Oplev laser power is falling

Rana, Steve

We investigated the ETMY oplev table set up and did not find a red herring.

Two 2 years  vs one day plot below.

ps: thanks  Q for fixing  DTT, the auto scaling is not working at sampling rate 10 min and 1 hr period?? surprise

 

Attachment 1: ETMYoplev2y.png
ETMYoplev2y.png
  499   Sun May 25 22:33:00 2008 ranaUpdateSUSETMY Oplev Work
I found the ETMY table in disarray and put the panels back on and put the ETMY OL laser back on the quad.

The next thing to do is clean up the table (there's a lot of junk on it) and then put in a lens within
6" of the laser to focus the beam on the quad (no metal diving boards and the lens should be either
uncoated (from our Edmunds collection) or a red lens, not 1064).

Then we have to put the beam cover back on between the viewport and the table.
  13060   Mon Jun 12 17:42:39 2017 gautamUpdateASSETMY Oplev Pentek board pulled out

As part of my Oplev servo investigations, I have pulled out the Pentek Generic Whitening board (D020432) from the Y-end electronics rack. ETMY watchdog was shutdown for this, I will restore it once the Oplev is re-installed.

  13267   Tue Aug 29 15:04:59 2017 gautamUpdateSUSETMY Oplev PIT loop gain changed

Last night, while we were working on the ALS, I noticed the GTRY spot moving around (in PITCH) on the CCD monitor in the control room at ~1-2Hz. The operating condition was that the arm was locked to the IR, and the PSL green shutter was closed, so that only the arm transmissions were visible on the CCD screens. There was no such noticable movement of the GTRX spot. When looking at the out-of-loop ALS nosie in this configuration (but now with the PSL green shutter open of course), the Y arm ALS noise at low frequencies was much worse than the X arm.

Today, I looked into this a little more. I first checked that the Y-endtable enclosure was closed off as usual (as I had done some tweaking to the green input pointing some days ago). There are various green ghost beams on the Y-endtable. When time permits, we should make an effort to cleanly dump these. But the enclosure was closed as usual.

Then I looked at the in-loop Oplev error signal spectra for the ITMY and ETMY Oplev loops. There was high coherence between ETMYP Oplev error signal and GTRY. So I took a loop transfer function measurement - the upper UGF was around 3.5Hz. I increased the loop gain such that the upper UGF was around 4.5Hz, with phase margin ~30degrees. Doing so visibly reduced the angular movement of the GTRY spot on the CCD. Attachment #1 shows the Oplev loop TF after the gain increase, while Attachment #2 compares the GTRX and GTRY spectra (DC value is approximately the same for both, around 0.4). GTRY still seems a bit noisier at low frequencies, but the out-of-loop ALS noise for the Y arm now lines up much more closely with its reference trace from a known good time. 

Quote:
 

Y-arm ALS wasn't so stellar tonight, especially at low frequencies. I can see the GTRY spot moving on the CCD monitor, so something is wonky. To be investigated.

 

Attachment 1: ETMY_OLPIT.pdf
ETMY_OLPIT.pdf
Attachment 2: GTR_comparison.pdf
GTR_comparison.pdf
  12746   Mon Jan 23 15:16:52 2017 gautamUpdateOptical LeversETMY Oplev HeNe needs to be replaced

On the control room monitors, I noticed that the IR TEM00 spot was moving around rather a lot in the Y arm. The last time this happened had something to do with the ETMY Oplev, so I took a look at the 30 day trend of the QPD sum, and saw that it was decaying steeply (Steve will update with a long term trend plot shortly). I noticed the RIN also seemed rather high, judging by how much the EPICS channel reading for the QPD sum was jumping around. Attached are the RIN spectra, taken with the OL spot well centered on the QPD and the arms locked to IR. Steve will swap the laser out if it is indeed the cluprit.

Attachment 1: ETMY_Oplev.pdf
ETMY_Oplev.pdf
  14402   Tue Jan 15 18:16:00 2019 gautamUpdateOptical LeversETMY Oplev HeNe needs replacement

Perhaps the ETMY Oplev HeNe is also giving up - the power has fallen by ~30% over 1 year (Attachment #2), nearly twice as much as ETMX but the RIN spectrum (Attachment #1, didn't even need to rotate it!) certainly seems suspicious. Some "nominal" RIN levels for HeNes can be found earlier in this thread. I can't close any of the EY Oplev loops in this condition. I'll double check to make sure I'm routing the right beam onto the QPD, but if the problem persists, I'll replace the HeNe. ITMX HeNe also looks to be near EOL.

Quote:

Finally I reallized what is killing the ETMY oplev laser. Wrong  power supply, it  was driving the HeNe laser by 600V higher voltage than recommended. Power supply 101T-2300Vdc replaced by 101T-1700Vdc ( Uniphase model 1201-1, sn 2712420 )

The laser head 1103P, sn P947049 lived for 120 days and it was replaced by sn P964431   New laser output 2.8 mW,  quadrant sum 19,750 counts

Attachment 1: OLRIN.pdf
OLRIN.pdf
Attachment 2: OLsums.png
OLsums.png
  12747   Mon Jan 23 17:24:26 2017 SteveUpdateOptical LeversETMY Oplev HeNe is running hot

ETMY He/Ne 1103P  body temp is  ~45 C The laser was seated loosely  in the V-mount with black rubber padding.

The enclosure has a stinky plastic smell from this black plastic. This laser was installed on Oct 5, 2016 See 1 year plot.

Oplev servo turned off. Thermocouple attached to the He/Ne

It will be replaced tomorrow morning.

Quote:

On the control room monitors, I noticed that the IR TEM00 spot was moving around rather a lot in the Y arm. The last time this happened had something to do with the ETMY Oplev, so I took a look at the 30 day trend of the QPD sum, and saw that it was decaying steeply (Steve will update with a long term trend plot shortly). I noticed the RIN also seemed rather high, judging by how much the EPICS channel reading for the QPD sum was jumping around. Attached are the RIN spectra, taken with the OL spot well centered on the QPD and the arms locked to IR. Steve will swap the laser out if it is indeed the cluprit.

 

Attachment 1: ETMY_oplev__lasers.png
ETMY_oplev__lasers.png
  12750   Tue Jan 24 17:52:15 2017 CraigUpdateOptical LeversETMY Oplev HeNe is replaced

Steve, Craig, Gautam

Today Steve replaced the ETMY He/Ne sr P919645 OpLev laser with sr P947049 and Craig realigned it using a new AR coated lenses.

Attached are the RIN of the OpLev QPD Sum channels.  The ETMY OpLev RIN is much lower than when Gautam took the same measurement yesterday.

Also attached are the pitch and yaw OLG TFs to ensure we still have acceptable phase margins at the UGF.

The last three plots show the optical layout of the ETMY OpLev, a QPD reflection blocker we added to the table, and green light to ETMY not being blocked by any changes to the OpLev.

Quote:

ETMY He/Ne body temp is  ~45 C The laser was seated loosely  in the V-mount with black rubber padding.

The enclosure has a stinky plastic smell from this black plastic. This laser was installed on Oct 5, 2016 See 1 year plot.

Oplev servo turned off. Thermocouple attached to the He/Ne

It will be replaced tomorrow morning.

Quote:

On the control room monitors, I noticed that the IR TEM00 spot was moving around rather a lot in the Y arm. The last time this happened had something to do with the ETMY Oplev, so I took a look at the 30 day trend of the QPD sum, and saw that it was decaying steeply (Steve will update with a long term trend plot shortly). I noticed the RIN also seemed rather high, judging by how much the EPICS channel reading for the QPD sum was jumping around. Attached are the RIN spectra, taken with the OL spot well centered on the QPD and the arms locked to IR. Steve will swap the laser out if it is indeed the cluprit.

 

 

Attachment 1: OpLevRIN24Jan2017.pdf
OpLevRIN24Jan2017.pdf
Attachment 2: ETMYpit_24Jan2017.pdf
ETMYpit_24Jan2017.pdf
Attachment 3: ETMYyaw_24Jan2017.pdf
ETMYyaw_24Jan2017.pdf
Attachment 4: IMG_3510.JPG
IMG_3510.JPG
Attachment 5: IMG_3513.JPG
IMG_3513.JPG
Attachment 6: IMG_3514.JPG
IMG_3514.JPG
  13018   Tue May 30 13:36:58 2017 SteveUpdateOptical LeversETMY Oplev HeNe is replaced

Finally I reallized what is killing the ETMY oplev laser. Wrong  power supply, it  was driving the HeNe laser by 600V higher voltage than recommended. Power supply 101T-2300Vdc replaced by 101T-1700Vdc ( Uniphase model 1201-1, sn 2712420 )

The laser head 1103P, sn P947049 lived for 120 days and it was replaced by sn P964431   New laser output 2.8 mW,  quadrant sum 19,750 counts

 

Attachment 1: oplevETMY120d.png
oplevETMY120d.png
  8749   Tue Jun 25 23:49:04 2013 AnnalisaUpdateSUSETMY Oplev

I had some problem with the Oplev Servo today. I was working at the mode matching fine tuning and I left the Oplev servo enabled while aligning.

When I opened the Yend table lids, the Oplev beam started moving on the QPD and the Oplev servo didn't help in stopping the mirror movement, but it increased it.

So, the mirror was oscillating at a frequency of a few Hz

Koji suggested that maybe the shaking is due to the air conditioning moving the beam, so the servo tries to feed back the signal to the mirror, even if the mirror doesn't actually move.

I also measured the transfer function for the Oplev, but it didn't show any strange behavior.

  12430   Mon Aug 22 18:04:24 2016 gautamUpdateSUSETMY OSEMs inserted

[Johannes, gautam]

We worked on trying to insert the OSEMs in the optimal positions such that the coupling of the bounce mode into the OSEM sensor signals was minimised.

First, I gave the barrel of the optic a wipe with some optical tissue + acetone in order to remove what looked like some thin fibres of dried first contact. It may be that while I was applying the F.C., the HEPA air flow deposited these on the barrel. In any case, they came off easily enough. There is still a few specks of dust on various parts of the barrel, but it is likely that these can just be removed with the ionized air jet, which we can do after putting the optic in the chamber.

We then did the usual OSEM insertion till the magnets neutral position was such that the sensor output was ~50% of the fully open value (turned the HEPA off for the remainder of this work). I tweaked the bottom OSEM plate a little in order to center the magnets relative to the coil as best as possible. Once this was done, we attempted to look at spectra of the sensor outputs, with 0.05 Hz bandwidth - however, we were unable to identify any peak at 16.4 Hz, which is what a Jan 2015 measured value wiki page claims the bounce mode frequency is (although this was an in vacuum measurement). There were a couple of peaks at ~15.7 Hz and ~16.7 Hz, but I can't think of any reason why the bounce mode resonance should have changed so much - after all, this is ETMY for which no standoff regluing was done. The only difference is that there is some first contact + peek mesh on the HR face now, but I doubt this can modify the bounce resonance frequency so much (this is just my guess, I will have to back this up with a calculation).

Anyways we decided to take this up again tomorrow. Things are progressing fairly well now, I hope to be able to put in ETMY back into the chamber at some point tomorrow and commence re-alignment of the interferometer. I've left the OSEMs in for today, with the EQ stops not engaged but close by. HEPA has been turned back on.

  14409   Sat Jan 19 15:33:18 2019 gautamUpdateSUSETMY OSEMs faulty

After diagnosis with the tester box, as I suspected, the fully open DC voltages on the two problematic channels, LL and UR, were restored once I replaced the LM6321 ICs in those two channel paths. However, I've been puzzled by the inability to turn on the Oplev loops on ETMY. Furthermore, the DC bias voltages required to get ETMY to line up with the cavity axis seemed excessively large, particularly since we seemed to have improved the table levelling.

I suspected that the problem with the OSEMs hasn't been fully resolved, so on Thursday night, I turned off the ETMY watchdog, kicked the optic, and let it ringdown. Then I looked at the time-series (Attachment #1) and spectra (Attachment #2) of the ringdowns. Clearly, the LL channel seems to saturate at the lower end at ~440 counts. Moreover, in the time domain, it looks like the other channels see the ringdown cleanly, but I don't see the various suspension eigenmodes in any of the sensor signals. I confirmed that all the magnets are still attached to the optic, and that the EQ stops are well clear of the optic, so I'm inclined to think that this behavior is due to an electrical fault rather than a mechanical one.

For now, I'll start by repeating the ringdown with a switched out Satellite Box (SRM) and see if that fixes the problem. 

Quote:

While restoring OSEMs on ETMY, I noticed that the open voltages for the UR and LL OSEMs had significantly (>30%) changed from their values from ~2 years ago. The fact that it only occurred in 2 coils seemed to rule out gradual wear and tear, so I looked up the trends from Nov 25 - Nov 28 (Sundance visited on Nov 26 which is when we removed the cage). Not surprisingly, these are the exact two OSEMs that show a decrease in sensor voltage when the OSEMs were pulled out. I suspect that when I placed them in their little Al foil boats, I shorted out some contacts on the rear (this is reminiscent of the problem we had on PRM in 2016). I hope the problem is with the current buffer IC in the satellite box and not the physical diode, I'll test with the tester box and evaluate the problem further.

Attachment 1: Screen_Shot_2019-01-19_at_3.32.35_PM.png
Screen_Shot_2019-01-19_at_3.32.35_PM.png
Attachment 2: ETMY_sensors_1231832635.pdf
ETMY_sensors_1231832635.pdf
  14411   Tue Jan 22 20:36:53 2019 gautamUpdateSUSETMY OSEMs faulty

Short update on latest Satellite box woes.

  1. I checked the resistance of all 5 OSEM coils on ETMY using a DB25 breakout board and a multimeter - all were between 16-17 ohms (mesured from the cable to the Vacuum flange), which I think is consistent with the expected value.
  2. Checked the bias voltage (aka slow path) from the coil driver board was reaching the coils
    • The voltages were indeed being sent out of the coil driver board - I confirmed by driving a slow sine wave and measuring at the output of the coil driver board, with all the fast outputs disabled.
    • The voltage is arriving at the 64 pin IDC connector at the Satellite box - Chub and I verified this using some mini-grabbers and leads from wirewound resistors (we don't have a breakout board for this kind of connector, would be handy to get some!)
    • However, the voltages are not being sent out through the DB25 connectors on the side of the Satellite box, at least for the LL and UR channels. UL seems to work okay.
    • This behavior is consistent with the observation that we had to apply way larger bias voltages to get the cavity axis to line up than was the nominal values - if one or more coils weren't getting their signals, it would also explain the large PIT->YAW coupling I observed using the Oplev spot and the slow bias alignment EPICS sliders.
    • This behavior is puzzling - the Sat box is just supposed to be a feed-through for the coil driver signals, and we measured resistances between the 64 pin IDC connector and the corresponding DB25 pins, and measured in the range of 0.2-0.3 ohms. However, the voltage fails to make it through - not sure what's going on here.. We will investigate further on the electronics bench.

What's more - I did some Sat box switcheroo, swapping the SRM and ETM boxes back and forth in combination with the tester box. In the process, I seem to have broken the SRM sat box - all the shadow sensors are reporting close to 0 volts, and this was confirmed to be an electronic problem as opposed to some magnet skullduggery using the tester box. Once we get to the bottom of the ETMY sat box, we will look at SRM. This is more or less the last thing to look at for this vent - once we are happy the cavity axis can be recovered reliably, we can freeze the position of the elliptical reflector and begin the F.C.ing.

  11668   Mon Oct 5 16:41:22 2015 SteveUpdateSUSETMY OL laser replaced

This JDSU 1103P laser, sn P892324 lived for 2 years. It's power output is 0.05 mW now

It was replaced with brand new JDSU 1103P,  sn P919645, Mfg date 12/2014 with 2.75 mW output.

There is 0.14 mW  light returning to the qpd = 7,250 counts without AR 632 lenses

  11667   Mon Oct 5 11:25:21 2015 ericqUpdateSUSETMY OL laser dead

Gautam alerted me that the Y arm looked like it was being dithered, even though the ASS was turned off. I found that the ETMY OL signals were garbage, leading to the servos flipping back and forth between their rails. 

We went out to the ETMY table, and found the HeNe laser to be emitting a paltry <0.5mW; the OL QPD could not register the puny beam incident on it.

Here is the last 30 days of OL_SUM:

Steve will replace the laser this afternoon. 

  14447   Mon Feb 11 16:38:34 2019 gautamUpdateLSCETMY OL calibration updated

Since we changed the HeNe, I updated the calibration factors, and accepted the changes in the SDF.

DOF OLD [urad/ct] NEW [urad/ct]
PITCH 140 176
YAW 143

193

Attachment 1: OL_calib_ETMY_PERROR.pdf
OL_calib_ETMY_PERROR.pdf
Attachment 2: OL_calib_ETMY_YERROR.pdf
OL_calib_ETMY_YERROR.pdf
  12349   Thu Jul 28 17:48:17 2016 gautamUpdateGeneralETMY LR magnet broke off

While ETMX magnets were curing, I wanted to try and suspend ETMY in the endchamber, put in the OSEMS and see if the magnets aligned well with the coils, and run the same type of diagnostics we have been doing for ETMX. However, while I was trying to slip the optic into the wire, the UL magnet on ETMY broke off. I recovered the magnet and now both optic and magnet are back in the cleanroom. The magnet dumbbell has been cleaned with acetone and then sandpaper to remove residual epoxy - it remains to clean the residue off the optic itself before re-gluing the magnet tonight

I also noticed that the existing wire in the suspension had a kink in it. It looks fairly sharp, and I think we should change the wire while re-inserting the optic. Putting the optic into an existing loop of wire is tricky, as if you go in from the front of the suspension cage, the magnets on the AR side attract the wire, and makes it quite difficult to loop the wire around. I have to think of some way of holding the wires in place while the optic is being placed, and then, once the optic is roughly in position, slip the wire into the grooves in the standoffs. 


I took the opportunity to replace the face OSEM coil holder screws while the chamber was open. 

EDIT 9 August 2016: It was in fact the LR magnet that was knocked off.

ELOG V3.1.3-