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ID Date Author Type Category Subjectup
  15885   Tue Mar 9 12:41:29 2021 KojiSummaryElectronicsInvestigation on the invacuum Dsub cables

I believe the aLIGO style invac dsub cables and the conventional 40m ones are incompatible.
While the aLIGO spec is that Pin1 (in-vac) is connected to the shield, Pin13 (in-vac) is the one for the conventional cable. I still have to check if Pin13 is really connected to the shield, but we had trouble before for the IO TTs https://nodus.ligo.caltech.edu:8081/40m/7864.
(At least one of the existing end cables did not show this Pin13-chamber connection. However, the cables OMC/IMC chambers indicated this feature. So the cables are already inhomogenious.)

- Which way do we want to go? Our electronics are updated with aLIGO spec (New Sat amp, OMC electronics, etc), so I think we should start making the shift to the aLIGO spec.

- Attachment Top: The new coil drivers can be used together with the old cables using a custom DB25 cable (in-air).

- Attachment Mid: The combination of the conventional OSEM wiring and the aLIGO in-vac cable cause the conflict. The pin1 which is connected to the shield is used for the PD bias.

- Attachment Bottom: This can be solved by shifting the OSEMs by one pin.

Notes:
o The aLIGO cables have 12 twisted pair wires, but paired signals do not share a twisted pair.
   --- No. This can't be solved by rotating the connectors.
o This modification should be done only for the new suspension.
   --- In principle, we can apply this change to any SOSs. However, this action involves the vent. We probably want to install the new electronics for the existing suspensions before the vent.
o ^- This means that we have to have two types of custom DB25 in-air cables.
   --- Each cable should handle "Shield wire" from the sat amp correctly.

Related Links:

Active TT Pin Issue
https://nodus.ligo.caltech.edu:8081/40m/7863
and the thread

Hacky solution
https://nodus.ligo.caltech.edu:8081/40m/7869

Photo
https://photos.google.com/u/1/album/AF1QipOEDi7iBdS4EHcpM7GBbv9l6FiJx-Tkt1I2eSFA
Active TT Pin Swapping (December 21, 2012)

TT Wiring Diagram (Wiki)
https://wiki-40m.ligo.caltech.edu/Suspensions/Tip_Tilts_IO

Attachment 1: SOS_OSEM_cabling.pdf
SOS_OSEM_cabling.pdf
  10847   Tue Dec 30 00:46:05 2014 ranaUpdateIOOInvestigations into the mad PCDRIVE

Koji and I noticed that there was a comb* of peaks in the MC and FSS at harmonics of ~37 kHz. Today I saw that this shows up (at a much reduced level) even when the input to the MC board is disconnected.

It also shows up in the PMC. At nominal gains, there is just the 37 kHz peak. After tweaking up the phase shifter settings, I was able to get PMC servo to oscillate; it then makes a comb, but the actual oscillation fundamental is 1/3 of 37 kHz (some info on Jenne from elog 978 back in 2008).

Not sure what, if anything, we do about this. It is curious that the peak shows up in the MC with a different harmonic ratio than in the PMC. Any theories?

 

Anyway, after some screwing around with phase and amplitude of the RF modulation for the PMC from the phase shifter screen**, I think the gain is higher in the loop and it looks like the comb is gone from the MC spectrum.

Another clue I notice is that the PCDRIVE mad times often are coincident with DC shifts in the SLOWDC. Does this mean that its a flakiness with the laser? While watching the PCDRIVE output from the TTFSS interface board on a scope, I also looked at MIXER mon. It looks like many of the high noise events are associated with a broadband noise increase from ~50-140 kHz, rather than some specific lines. Don't know if this is characteristic of all of the noisy times though.

 

* this 'comb' had several peaks, but seem not be precise harmonics of each other: (f3 - 3*f1)/f3 ~ 0.1%

** I think we never optimized this after changing the ERA-5 this summer, so we'd better do it next.

 *** UPDATE: the second plot show the comparison between the new quiet and noisy states. Its just a broad bump.

 

Attachment 1: MC_ERR.pdf
MC_ERR.pdf
Attachment 2: plotFSSerr.ipynb.xz
Attachment 3: MC_ERRcomp.pdf
MC_ERRcomp.pdf
  11764   Sat Nov 14 00:52:25 2015 KojiSummaryCDSInvestion on EPICS freeze

[Yutaro, Koji]

Recently "EPICS Freeze" is so frequent and the normal work on the MEDM screen became almost impossible.

As a part of the investigation, all 19 realtime processes were stopped in order to see any effect on the probem.

IN FACT, when the realtime processes were absent (still slow machines were running), frequency of EPICS Freeze
became much less. This might mean that the issue is related to the data collection of the slow channels. We need more investigation.

After the testing, all the processes were restored although it was not so straghtforward. Particularly, c1sus DAC had an error which was
not visible from the CDS Status screen. We noticed it as suspension damping was not effective on any of the vertex suspensions.
This has been solved by restarting c1x02 process.

  14720   Tue Jul 2 17:34:54 2019 gautamUpdateLSCIrides opened up on EY table

In preparation for the ASS debugging, I decided to check out the beam path on the EY table. In order to be able to do this, I had to setup the POY locking to trigger on AS110 instead of TRY (as is usual for this kind of debugging). Then I could poke an IR card in the beam path without destroying the lock.

There are two irides in the beam path immediately between the vacuum window and the harmonic separator that splits off the IR and green beams. I found that the beam was in fact getting clipped on both of them. It was also somewhat off center on a 2" beamsplitter that sends half of the light to the QPD (currently decommissioned). The purpose of these irides are (I think) to eliminate some ghost reflections of the green beam and also the Oplev beam. I opened up the irides until I felt that there wasn't any more clipping of the IR beam, but the appropriate ghost beams were still getting caught.

I also re-aligned the beam onto the TRY Thorlabs PD so as to better center it on the active area. In summary, the result of this work was that the TRY level went from ~0.6 to ~0.93. There may still be some scope for optimizing this - I tried running the Y-arm ASS scripts, and already, the loops don't run away any more. I'll do the systematic analysis of the servo anyways. But given that the IMC Trans lev el used to be ~15,500 counts and is now ~14,500 counts, I think ~7% drop in TRY level is in line with what we "expect" (assuming the pre-power-degradation TRY level was 1.000).

Note that these irides were installed (I think) by Yuki, and so cannot explain the ASS anomalies of July 2018 (i.e. it does not exonerate in-vacuum clipping of the beam, as Koji had already verified that the in-air path was clean back then).

  16535   Thu Dec 23 16:38:21 2021 KojiUpdateGeneralIs megatron down? (Re: chiara local backup)

The local backup seems working fine again. But I found that megatron is down and this is a real issue. This should be fixed at the earliest chance.


It seems that the local backup has been successfully taken this morning.

controls@nodus|backup> tail /opt/rtcds/caltech/c1/scripts/backup/localbackup.log
2021-12-19 07:00:01,146 INFO       Updating backup image of /cvs/cds
2021-12-19 07:00:01,146 ERROR      External drive not mounted!!!
2021-12-20 07:00:01,255 INFO       Updating backup image of /cvs/cds
2021-12-20 07:00:01,255 ERROR      External drive not mounted!!!
2021-12-21 07:00:01,361 INFO       Updating backup image of /cvs/cds
2021-12-21 07:00:01,361 ERROR      External drive not mounted!!!
2021-12-22 07:00:01,469 INFO       Updating backup image of /cvs/cds
2021-12-22 07:00:01,470 ERROR      External drive not mounted!!!
2021-12-23 07:00:01,594 INFO       Updating backup image of /cvs/cds
2021-12-23 07:19:55,560 INFO       Backup rsync job ran successfully, transferred 338425 files.

However, I noticed that the autoburt has been stalled since Dec 6 (I used to check how the backup is up-to-date using the autoburt snapshots)

Dec>pwd
/opt/rtcds/caltech/c1/burt/autoburt/snapshots/2021/Dec
Dec>ls -l
total 24
drwxr-xr-x 26 controls controls 4096 Dec  1 23:07 1
drwxr-xr-x 26 controls controls 4096 Dec  2 23:07 2
drwxr-xr-x 26 controls controls 4096 Dec  3 23:07 3
drwxr-xr-x 26 controls controls 4096 Dec  4 23:07 4
drwxr-xr-x 26 controls controls 4096 Dec  5 23:07 5
drwxr-xr-x 19 controls controls 4096 Dec  6 16:07 6

There are a bunch of errors in the log file as follows, but maybe this is not an issue

controls@nodus|burt> pwd
/opt/rtcds/caltech/c1/burt
controls@nodus|burt> tail burtcron.log
!!!  ERROR !!! Target c1supepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1tstepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1x10epics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1aux Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1dcuepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1iscaux Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1iscepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1losepics Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1psl Snapshot file inconsistent with Request file
!!!  ERROR !!! Target c1susaux Snapshot file inconsistent with Request file

The real issue seems that megatron is down. It has a lot of house keeping jobs on corn including the N2 pressure alert.
https://wiki-40m.ligo.caltech.edu/Computers_and_Scripts/CRON
This needs to be fixed at the earliest chance.

  16536   Fri Dec 24 16:49:41 2021 KojiUpdateGeneralIs megatron down? (Re: chiara local backup)

It turned out that the UPS installed on Nov 22 failed (cf https://nodus.ligo.caltech.edu:8081/40m/16479 ). As a fact, it was alive just for 2 weeks!

The APC UPS unit indicated F06. According to the manual (https://www.apc.com/shop/us/en/products/APC-Power-Saving-Back-UPS-Pro-1000VA/P-BR1000G), F06 means "Relay Welding" and can not be fixed by a user. Resetting the UPS eliminated the error, but I didn't want to have the same issue while no one is in the lab, I moved the megatron power source from the UPS to the power strip on 1Y7. So, megatron is currently vulnerable to a power glitch.

After the power cords were restored, megatron eventually recovered ssh terminals. I manually ran autoburt.cron at 16:50 so that the latest snapshot is taken.

Attachment 1: PXL_20211224_235652821.jpg
PXL_20211224_235652821.jpg
  9965   Fri May 16 16:08:12 2014 steveUpdateLSCIsolating base plates

 Electronic components should be ISOLATED as they are installed on the optical tables.

This is essential to avoid ground loops, 60 Hz and harmonic peaks in the spectrum. We have just got some made.

Please only use it for this reason. Earlier black delrin base plates were used up in not needed places.

 

The anodized Aluminum base plates with magenets certainly will conduct.

 

Attachment 1: ISObaseplates.jpg
ISObaseplates.jpg
  4328   Fri Feb 18 20:17:07 2011 JoonhoSummaryElectronicsIsolation of Voltage regulator

Today I was working on RF distribution box.

So far I almost finished to electronically isolate voltage regulators from the box wall by inserting mica sheet, sleeve, and washers.

 

The problem I found is the resistance between wall and the voltage regulator is order of M ohms

I checked my isolation (mica sheet and sleeve and washer) but there is no problem there.

But I found that the power switch is not completely isolated from the wall.( around 800 kohm)

and that the resistance between the regulator and the wall is smaller for the regulator closer to the power switch

and greater for the regulator less closer to it.

So I think we need to put washer or sleeve to isolate the powersitch electronically from the box wall.

Suresh or I will fix this problem

[ To Suresh, I can finish the isolation when I come tomorrow. Or you can proceed to finish isolation.]

  9070   Tue Aug 27 15:44:08 2013 manasaUpdateCDSIssues with ALS fixed

I figured out the problem with ALS from yesterday. While the model was just fine, the medm screens were not checked if they were reading the correct channel names. 

The channel names of the ALS input matrix elements had changed when the coarse channels were deleted from the c1als model. So the error signals were not reaching the servo modules as expected. This is why I was not able to make sense as to what the ALS was doing. 

All is fixed now and should be back to normal

  544   Wed Jun 18 18:50:09 2008 ranaUpdateComputersIt can only be attributable to human error. (HAL - 2001)
There has been another one of "those" events and all of the front end machines are down.

We poked around and Rob determined that the FEs can't get the EPICS data from EPICS. The
dcuepics machine is hooked up and running and all of the epics binaries are running. We also
tried resetting its RFM switch as well as power cycling the box using the "poweroff" command.


Not a sausage.

Rob points out that although the Signal Detect lights are on on the cards, the 'Own Data' light
is not on on the dcuepics' card although it is on for some of the cards on the other boxes.


We have placed messages with the Russian. If anyone sees him, don't let him go without fixing things.
Also, make sure to follow him around with notepad and possibly a camera to record what it is that
he does. If he's muttering, maybe try to use a sensitive hidden sound recorder.
  338   Fri Feb 22 20:42:44 2008 AndreySummaryComputer Scripts / ProgramsIt seems I succeeded in theoretical simulations

I am pretty happy at this moment.

I definitely feel that it took me too much time to understand how to do the Matlab program and how to overcome difficulties,

but eventually at last my Matlab program seems to start working.

Briefly: What the program does?
--> take time-domain signal from two accelerometers near ITMX and ETMX (use 'get_data');
--> calculate the time-evolution of those two signals through the system "stack + pendulum" to the test-masses ITMX and ETMS (use 'lsim' in Matlab),
which gives us the time-domain evolution of the deviation of the position of individual test-mass from its average position.
--> Subtract the two results from each other in time-domain, this gives us the deviation of the length of the XARM-cavity from its average value
(roughly speaking, deviation of the length of the cavity from exactly 40 meters, although I am aware that the exact average length of XARM is less than 40 meters).
--> Take the amplitude spectrum of the result, using Sqrt(pwelch) and calibrate it from "counts" to "meters".
--> Calculate root-mean-square of peaks at different frequency intervals, for example near 0.8Hz,
and plot the three-dimensional surface showing the dependence of RMS on Q-factors Q_{ETMX} and Q_{ITMX}.

Eventually I am able to create these dependences of RMS.

I see that the minimum of the dependence is close to the diagonal corresponding to exact equality of Q_ETMX} and Q_{ITMX}, but not exactly along the diagonal. The plot allows to say
which of two conditions "Q_I > Q_E" or "Q_E < Q_I" should be fullfilled for optimization reasons. My plot is raw, I might have made a mistake in axis-label, I do not garantee now that the axis label "Q_ITMX - Q_ETMX" is correct,
maybe I need to change it for "Q_ETMX - Q_ITMX". I need some more time to determine this on Monday, but clearly there is asymmetry between Q_I and Q_E.

The peak at 0.8 Hz is pretty stable, while the peak at around 3Hz is not very repeatable, therefore in both experimental measurements and these simulations the amplitude of RMS of peak at 3Hz) is several orders of magnitude smaller than for RMS of peak at 0.8Hz, and I do not see minimum somewhere in the RMS-dependence, I see now only steady growth of RMS as Q_factors increase.

I will need to spend some time on Monday trying to understand how the sampling frequency and number of fft-points influence my results when I take amplitude spectrum using pwelch-command, as well I will need to double-check the correctness of normalization from counts to meters (I am not confident right now that amplitude of order of 10^(-12) meters is correct).

So, I need some time after the weekend to analyze my results and maybe make some slight changes, but I am glad that my Matlab model started to work in principle. I wanted to let others know about the status of the progress in my work. The fact that Matlab program works now is a good ending of a week.

Andrey.
Attachment 1: RMS_peak_08Hz-Theoretical.png
RMS_peak_08Hz-Theoretical.png
Attachment 2: RMS_peak_08Hz-QI-QE.png
RMS_peak_08Hz-QI-QE.png
Attachment 3: RMS_peak_3Hz-Theoretical.png
RMS_peak_3Hz-Theoretical.png
Attachment 4: RMS_peak_broad-interv-Theoretical.png
RMS_peak_broad-interv-Theoretical.png
  2971   Fri May 21 16:41:38 2010 Alberto, JoUpdateComputersIt's a boy!

Today the new Dell computer for the GSCS (General SURF Computing Side) arrived.

We put it together and hooked it up to a monitor. And guess what? It works!

I'm totally impressed by how the Windows get blurred on Windows 7 when you move them around. Good job Microsoft! Totally worth 5 years of R&D.

  14553   Fri Apr 19 09:42:18 2019 KojiBureaucracyGeneralItem borrowing (40m->OMC)

Apr 16, 2019
Borrowed two laser goggles from the 40m. (Returned Apr 29, 2019)
Apr 19, 2019
Borrowed from the 40m:
- Universal camera mount
- 50mm CCD lens
- zoom CCD lens (Returned Apr 29, 2019)
- Olympus SP-570UZ (Returned Apr 29, 2019)
- Special Olympus USB Cable (Returned Apr 29, 2019)

 

  14756   Fri Jul 12 18:54:47 2019 KojiUpdateGeneralItem loan: optical chopper from Cryo Lab

Optical chopper borrowed from CryoLab to 40m

https://nodus.ligo.caltech.edu:8081/Cryo_Lab/2458

  13425   Fri Nov 10 18:57:41 2017 ranaSummaryElectronicsIthaca 1201 vs. SR560

I characterized the black Ithaca 1201 pre-amp that we had sitting in the racks. It works fine and the input referred noise is < 10 nV/rHz. I also checked that the filter selection switches on the front panel did what they claim and that the gain knob gives us the correct gain.

For comparison I have also included the G=100, 1000 input referred noise of one of the best SR560 that we have (s/n 02763) in the lab. Above a few Hz, the SR560 is better, but for low frequency measurements it seems that the 1201 is our friend.

As with the SR560, you don't actually get low noise performance for G < 100, due to some fixed output noise level.

Steve:  sn48332 of Ithaca 1201

Attachment 1: Ithaca1201.pdf
Ithaca1201.pdf
  3335   Fri Jul 30 17:52:12 2010 KojiConfigurationGeneralJacket

Jenne and I need our jackets. We removed them from the Rb clock.
Thanks for making them warm.
Probably a Scotland sweater would fit.

  3337   Fri Jul 30 19:20:15 2010 AlastairConfigurationGeneralJacket

Quote:

Jenne and I need our jackets. We removed them from the Rb clock.
Thanks for making them warm.
Probably a Scotland sweater would fit.

 Thanks for the loan guys.  I do have a lot of warm weather clothing at home that is not so necessary in the California climate.  I will find some suitable attire for the Rb clocks there.

  10155   Tue Jul 8 17:59:12 2014 jamieOmnistructureElectronicsJamie 1811 power supply fixed!

I finally made good on the LIFE TIME WARRANTY on the ancient, Jamie-made 1811 power supply with the faulty switch:

20140708_165010.jpg

Back to fully working form.  Hopefully I'll still be around the next time it breaks in 16 years.

  10156   Tue Jul 8 18:20:15 2014 jamieOmnistructureElectronicsJamie 1811 power supply fixed!

 Placed in PD cabinet in Y arm, next to the OTHER Jamie-made 1811 power supply from 1998.

  7879   Mon Jan 7 19:23:19 2013 ranaUpdateElectronicsJamie's 1811 PS from 1998

  1. Front Panel switch supplies power, but does not light up - its unsafe as is. Needs new switch.
  2. Output has current limiting (which is nice) and schematic inside the box (which is very nice).
  3. Output voltage is not filtered or regulated ? LM7812 / 7912 would do the trick - or pick a PS with 18V outputs to reg down to 15 V.
  4. Box needs rubber feet.
  5. Overall B-

Also, we still need to get a 32GB SD card for the new camera. It only has an 8GB one.

Attachment 1: SOLA-1021-1026.pdf
SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf
Attachment 2: jamie98.jpg
jamie98.jpg
  7683   Wed Nov 7 15:51:44 2012 JenneUpdateAlignmentJamie's tip tilt proposal

Steve's elog 7682 is in response to the conversation we had at group meeting re: Jamie's proposed idea of re-purposing the active tip tilts.

What if we use the active TTs for the PR and SR folding mirrors, and use something else (like the picomotors that Steve found from the old days) for our input steering?

  7684   Wed Nov 7 17:20:01 2012 jamieUpdateAlignmentJamie's tip tilt proposal

Quote:

Steve's elog 7682 is in response to the conversation we had at group meeting re: Jamie's proposed idea of re-purposing the active tip tilts.

What if we use the active TTs for the PR and SR folding mirrors, and use something else (like the picomotors that Steve found from the old days) for our input steering?

I think we will still need two active steering mirrors for input pointing into the OMC, after the SRC, so I think we'll still need two of the active TTs there.

My thought was about using the two active TTs that we were going to use as the input PZT replacements to instead replace the PR2/3 suspensions.  Hysteresis in PR2/3 wouldn't be an issue if we could control them.

With static input pointing, ie. leaving PZT2/3 as they are, I think we could use PRM and PR2/3 to compensate for most input pointing drift.  We might have to deal with the beam in PRC not being centered on PRM, though.

Koji's suggestion was that we could replace the PZTs with pico-motors.  This would give us all the DC input pointing control we need.

So I guess the suggestion on the table is to replace PZT1/2 with pico-motor mounts, and then replace PR2/3 with two of the active tip-tilts.  No hysteresis in the PRC, while maintaining full input pointing control.

  7686   Wed Nov 7 23:22:45 2012 ranaUpdateAlignmentJamie's tip tilt proposal

 With Picos, we lose the ability to dither the input beam as well as align the beam with the IFO locked. And the active TT will still have hysteresis, but also actuators. Once in vacuum, I'm not sure how we adjust them - what's the error signal for PR2/PR3 ?

If the interferometer is aligned, why not just pump down now? I'm not sure that we have evidence of TT hysteresis issues once people stop touching them.

  11454   Tue Jul 28 16:42:25 2015 SteveUpdateGeneralJamies entry was deleted

Sorry Jamie, I accidentally deleted your elog entry #11453

  6424   Fri Mar 16 10:37:52 2012 JenneUpdateElectronicsJenne Laser

Quote:

Here is a picture of the small black breadboard on which I have put together the PD characterisation setup.  It would be great if we can retain this portable set up as it is, since we keep reusing it every couple of weeks.  It would be convenient if we can fiber couple the path to the PD under test with a 2m long fiber.  Then we will not have to remove the PD from the optical table while testing it. 

 This is totally sweet Suresh!  I don't remember how much more fiber is coiled up under the plate that has the "Jenne Laser" label, but there's a reasonable amount.  It's not 2m, but maybe we can just extend the blue snakey thing some?

  11369   Mon Jun 22 14:21:42 2015 SteveMetaphysicsTreasureJenne and Den graduated

Last supper before departing at  "Grazie" El Portal. All the best on your journey!

Attachment 1: ls.jpg
ls.jpg
  4197   Tue Jan 25 00:09:54 2011 KojiUpdateGeneralJenne laser is at PSL Lab

I found Tara's elog entry that Jenne laser is at PSL Lab.
Since we recently use it frequently, we should be aware where it is now.

  17022   Wed Jul 20 14:12:07 2022 PacoSummaryGeneralJenne laser kaput!

[Koji, Yehonathan, Paco]

Koji pointed out that this laser was always driven with a current driver (which was not nearby), and after finding it on one of the rolling carts, we hooked up the system but found that the laser driver displayed open circuit near the usual 20mA operating point. We therefore have to conclude that this laser is no more. We will look for a reasonable replacement.

Quote:

[Paco, Yehonathan, JC]

We were trying to setup the Jenne laser to characterize the response of three 1811s that Yehonathan is using for his WOPA experiment (in QIL). We hooked up a ~ 5 VDC power supply to the bias tee and looked to see if there was any DC response in the REF PD. We used a DB9 breakout board and a DB9 cable, and saw some current being drawn. The DC current was a bit too high (500 mA), so we turned the DC voltage off, and realized the VDC power was reversed, probably along the DB9 cable which we didn't check before. As we flipped the power supply leads and turned power back on, we could no longer see any current even though the voltage was now right (or was it???). We would like to debug this laser, and continue using it if it still works (!), but there is negligible documentation either here or in the wiki, so if there are any known places to look at it would be helpful to know them.

 

  17023   Wed Jul 20 15:58:52 2022 KojiSummaryGeneralJenne laser kaput!

For troubleshooting, the proper laser driver (found beneath the AG network analyzer) was connected.
The current ~1mA was provided and the driver detected the "open circuit", which means the laser diode was busted.

https://dcc.ligo.org/LIGO-T060240

The laser diode in the parts list is: "GTRAN GaAs Strained QW Laser Diode, Part # LD-1060".

  17021   Wed Jul 20 11:58:45 2022 PacoSummaryGeneralJenne laser kaput?

[Paco, Yehonathan, JC]

We were trying to setup the Jenne laser to characterize the response of three 1811s that Yehonathan is using for his WOPA experiment (in QIL). We hooked up a ~ 5 VDC power supply to the bias tee and looked to see if there was any DC response in the REF PD. We used a DB9 breakout board and a DB9 cable, and saw some current being drawn. The DC current was a bit too high (500 mA), so we turned the DC voltage off, and realized the VDC power was reversed, probably along the DB9 cable which we didn't check before. As we flipped the power supply leads and turned power back on, we could no longer see any current even though the voltage was now right (or was it???). We would like to debug this laser, and continue using it if it still works (!), but there is negligible documentation either here or in the wiki, so if there are any known places to look at it would be helpful to know them.

  5475   Tue Sep 20 03:12:14 2011 AnamariaUpdateSUSJenne's Scripts started

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

  5476   Tue Sep 20 04:12:26 2011 JenneUpdateSUSJenne's Scripts started

Quote:

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

 Thanks!  I'll give them a little more time, then restore things.

  5477   Tue Sep 20 09:44:44 2011 JenneUpdateSUSJenne's Scripts started

Quote:

Quote:

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

 Thanks!  I'll give them a little more time, then restore things.

 I began restoring the optics at ~9:30am, so I have a full 6 hours of data, in case I need that much to separate the Pos/Side modes on some of the optics.  They are all damping again with their original matricies.

  5479   Tue Sep 20 14:53:13 2011 JenneUpdateSUSJenne's Scripts started

Quote:

Quote:

Quote:

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

 Thanks!  I'll give them a little more time, then restore things.

 I began restoring the optics at ~9:30am, so I have a full 6 hours of data, in case I need that much to separate the Pos/Side modes on some of the optics.  They are all damping again with their original matricies.

 So, clearly this was a kind of dumb idea.  There is nothing mechanical going on between our sensor inputs and our Pit/Pos/Yaw/Side DoF filter banks.  It's just math.  On the other hand, we now have a 3rd set of in-vac free swinging data, so I can (after all the suspensions are working) have a look at the drift in matrix elements over time.

In other news, after some meditation, and fitzing with DoF gain values, all of the IFO optics except for SRM now have their new input matricies, and are damping pretty nicely.  I need to go through and do an "eyeball" check to make sure that everything has a Q of ~5ish.  So far, I've kicked the optics, and watched that they damped fairly quickly, but I don't have a guesstimate of the Q's for each optic, for each DoF.

So, still to do:

Use another set of data and invert the SRM matrix DONE

Plug in the MC matricies, make sure they're okay. DONE

Check the Q's for all optics, all DoFs. 

  4612   Tue May 3 14:35:44 2011 Larisa ThorneConfigurationElectronicsJenne-Seismometer LPF project

 I was charge with making a Non-Inverting Op Amp Low Pass Feedback circuit for Jenne, which may somehow be integrated into a seismometer project she's working on.

 

Circuit diagram is attached. Calculations show that R1, R2 and C have the following relationship: if R1=10^n, R2=10^(n+1), C=10^(-n-4). For the particular circuit being modeled by the transfer function, R1=100 Ohm, R2=1k Ohm, and C=1uF.

Attached also is the circuit's Bode plot, showing frequency versus gain and phase, respectively. The frequency versus gain graph is true to what the circuit was calculated to generate: a gain of +20 and a cutoff frequency at 200Hz. Not sure what's going on with the frequency verus phase plot.

Attachment 1: SeisLPFdiagram.jpg
SeisLPFdiagram.jpg
Attachment 2: seisLPF.Bose.jpg
seisLPF.Bose.jpg
  4630   Wed May 4 17:32:06 2011 Larisa ThorneConfigurationElectronicsJenne-Seismometer LPF project

Building on what was posted previously

 

 

The configuration has now evolved into an Inverting Op Amp Feedback Low Pass Filter circuit.

Had to change out some components to satisfy conditions: R1=1k Ohm, R2=10k Ohm, C=0.1uF. These were changed in order to decrease the magnitude of the current passing through the op amp by a factor of 10 (10V supplied through the R1 resistor yields about 10mA). The configuration itself was changed from non-inverting to inverting in order to get the frequency vs. gain part of the Bode plot to continue to decrease across higher frequencies instead of leveling off around 4kHz.

Attachment 1: SeisLPF3.jpg
SeisLPF3.jpg
  4634   Thu May 5 12:01:53 2011 Larisa ThorneConfigurationElectronicsJenne-Seismometer LPF project

 Having finished the bulk of the work for the LPF itself ( see here ), I have begun trying to design the seismometer box to Jenne's specifications.

 

Currently looking into what the voltage buffer amplifier might look like for this.

 

 

Suggestions/corrections would be much appreciated!

 

 

Attachment 1: STS2diagram.png
STS2diagram.png
  4690   Wed May 11 16:04:36 2011 Larisa ThorneConfigurationElectronicsJenne-Seismometer LPF project

The schematic for the seismometer box from this last time  has been updated...

 

Koji was helpful for coming up with a general diagram for the voltage buffer amplifier, which has now been added to the configuration pictured below.

The only thing that remains now before I try to plot it with Eagle/LISO is to pick an op amp to use for the voltage buffer itself. Someone suggested THS4131 for that (upon Googling, it hit as a "high speed, low noise, fully-differential I/O amplifier"). It looks good, but is it the best option?

Attachment 1: STS2diagram2.png
STS2diagram2.png
  3454   Mon Aug 23 00:08:24 2010 JenneUpdateelogJoe, I think this's your cue...
  3664   Thu Oct 7 08:39:39 2010 steveBureaucracySAFETYJoonho receives safety training

Our new undergrad Joonho Lee received 40m specific basic safety training yesterday.

Yuta and Joonho are scheduled to participate in the LIGO-laser safety tutelage with Peter K on Oct 12

  4859   Wed Jun 22 18:50:45 2011 JamieSummaryGeneralJuly 2011 vent plan

Kiwamu and I have started to put together a vent plan on the 40m wiki:

http://blue.ligo-wa.caltech.edu:8000/40m/vent/201107

We will keep working on this (there's still a *lot* to fill in), but please help fill in the plan by adding questions, answers, procedures, preparations, etc.

 

  4861   Wed Jun 22 21:36:41 2011 ranaSummaryGeneralJuly 2011 vent plan

I put a paper Peet's bag with half of the Mini-Moos into George.

  16982   Fri Jul 8 23:10:04 2022 KojiSummaryGeneralJuly 9th, 2022 Power Outage Prep

The 40m team worked on the power outage preparation. The detailed is summarized on this wiki page. We will still be able to access the wiki page during the power outage as it is hosted some where in Downs.

https://wiki-40m.ligo.caltech.edu/Complete_power_shutdown_2022_07

  15082   Fri Dec 6 17:49:46 2019 ranaSummaryPEMJump test of seismometers: EX needs recentering

Yehonathan, please center the EX seismometer.

The attached PDF shows the seismometer signals (I'm assuming that they're already calibrated into microns/s) during the lab tour for the art students on 11/1. The big spike which I've zoomed in on shows the time when we were in the control room and we all jumped up at the same time. There were approximately 15 students each with a mass of ~50-70 kg. I estimate that out landing times were all sync'd to within ~0.1 s.

Attachment 1: Seismometers.pdf
Seismometers.pdf
Attachment 2: src.tgz
  15083   Sun Dec 8 20:15:41 2019 ranaSummaryPEMJump test of seismometers: EX needs recentering

I have re-centered the EX (and EY) seismometers. They are Guralp CMG40-T, and have no special centering procedure except cycling the power a few times. I turned off the power on their interface box, then waited 10s before turning it back on.

The fist atm shows the comparison using data from 8-9 PM Saturday night:

  1. there seems to be a factor of 2 calibration diff between the T240 near the BS, and the Guralp seismometers at the end. Which one is right? surpriseWhen was the last time they were cross calibrated?
  2. The low coherence between BS_X and EX_X shows the problem. They should be very coherent (> 0.9) for 0.1-1 Hz.sad

 

Attachment 1: seis_all_191208.pdf
seis_all_191208.pdf
  15086   Mon Dec 9 13:08:24 2019 YehonathanSummaryPEMJump test of seismometers: EX needs recentering

I check the seismometers in the last 14 hours (Attached). Seems like the coherenece is restored in the x direction.

 

 

Attachment 1: seis_191208.pdf
seis_191208.pdf
  9791   Wed Apr 9 02:34:20 2014 JenneUpdateLSCJumping over the CARM resonance point

Koji was right, and I was using much too large of a CARM offset.  Tonight, I set either my CARM or DARM offset to 3 counts, and was able to easily acquire PRMI lock using REFL33. 

For either CARM or DARM offset reduction (the other one was kept at zero offset), I was able to get to about 0.5 counts, but I lose lock when I try to go to 0.4 or 0.3 counts.  One time, I tried "jumping over" the resonance, by going from minus 1 to plus 1 in CARM offset.  Plots of this below.


Locking notes

ALS locked with "Xarm" servo as proxy for DARM, and "Yarm" servo as proxy for DARM.  Pushing only on ETMs today, not the MC. 

MICH / PRCL:

Input matrix:  1's in REFL 33 I&Q, if not using power normalization.  200's in REFL 33 I&Q if power normalization used (either POPDC or POP22).  200 used because that's about the average value of POPDC or POP22 when PRMI sideband-only resonant.

Trigger:  POP22, up 100, down 10.

Power normalization:  1's for both MICH and PRCL in POP22I for one trial.  1's for both MICH and PRCL in POPDC for another trial.  Both seemed to work equally well, although that may change when I'm actually getting IR resonance in the cavity.

FM triggers:  MICH = FM2.  PRCL = FMs 2, 3, 6, 9.  Trigger up = 35, down 10.  PRCL delayed by 0.5 sec, MICH delayed by 5 seconds.

Servo gains:  MICH = 0.4, PRCL = -0.01


Observations:

When I approach the situation of both arms resonating, it pretty consistently looks like the PRM is getting pushed in pitch (and not in yaw).  I don't know why this could be, but it seems like this is the big symptom before lockloss - if the POP spot starts moving (and the PRM suspit signal starts moving), PRMI lock is going to be lost.

I don't know if it's imperfect alignment, imperfect mode matching, or something else, but I see lots of high-order higher order modes on both the POP and AS cameras when the CARM or DARM offset is less than 1 count.  I tried to take a video, but the brightness and contrast aren't set as high as on monitors 3 and 5, so it's hard to see the dim stuff.  Youtube.  At the midpoint of the video, you see a lockloss.

Even though I have overridden the transmission triggers so that I only use the QPDs for the transmission signals, I'm only seeing arm transmission values up to about 50 from each arm.  If we had ideal PRC gain, we expect something like 650 or 700. 


A few plots

All of the raw data for these plots, and several other channels, is in /users/jenne/PRFPMI/PRMI_2arms_8Apr2014/m1_to_p1_carmOffset_1081065069.  As mentioned above, "XARM" is CARM, and "YARM" is DARM.  So, the XARM_IN1 tells us about the CARM offset that I was applying.  The start time is 1081065069, and the plots are all 8 seconds long.

First, the transmitted power and the CARM offset.

TRX_TRY_QPDonly.png

The REFL_I error signals and the CARM offset.

LSC_error_signals.png

The RF signals that we will eventually chose from for CARM and DARM control. Note that I'm not sure about the AS55 phase, so I plot both I and Q.

REFL1f_AS55.png

The PRM suspit and sus yaw angular signals and the CARM offset.  I don't see a huge change in the suspit signal, but it does seem to change character once we approach arm resonances.

PRM_SUSangles.png

  1388   Wed Mar 11 16:53:48 2009 YoichiUpdateLockingJunks in around kHz
Rana, Yoichi

Last night, we tried to find out the source of the kHz region peaks in the DARM and CARM error signals.
These peaks are also present in the error signal of the single arm locking by RF (both X and Y).
The attachment 1 shows spectra of MC_F and XARM error signal when XARM is locked by the POX PDH signal.
There is a sharp peak at 3.8kHz in MC_F. This peak was there in a reference spectrum taken on June 24 2008.

In the XARM error signal, there is also a broad peak around 3.8kHz. This peak moves between 3.75kHz and 3.8kHz from time to time.
(the brown curve was taken when the peak moved to 3.75kHz).
Also there is a notch like structure at 3.8kHz in the XARM error spectrum. Looks like the peak in the MC_F is creating a notch here, but
no idea why.

We tapped on the PSL table, the end chambers and the SPOB table and looked at the spectra to see if there is any change.
Rana also developed a cool Walkie-Talkie excitation technique, where he put one of the walkie-talkies on the PSL table by the MZ and yelled at the other one while looking at a DTT screen in the control room.
None of these had any effect on the XARM error, while MC_F responded to the disturbances.

We also turned on and off the steering mirror PZT closed loop buttons, moved the PMC, MZ and the ISS gain sliders and changed the MC gain, offset.
Nothing affected the XARM error.

Osamu found old spectra of the XARM signal (attm2). The legends say DARM but these are XARM signals.
Almost the same structures can be seen including the notch at 3.8kHz. Seems like it's been like this for long time.

We should check, RF-AM, MC coil dirivers, Piezo-Jena noise etc.
Attachment 1: MC_F-XARM.pdf
MC_F-XARM.pdf
Attachment 2: old-xarm.pdf
old-xarm.pdf
  3683   Sun Oct 10 16:44:59 2010 KojiOmnistructurePhotosKepco Tube HV supply
Attachment 1: IMG_3637.jpg
IMG_3637.jpg
Attachment 2: IMG_3640.jpg
IMG_3640.jpg
  2815   Tue Apr 20 10:55:10 2010 steveBureaucracySAFETYKevin Kuns received safety training

The 40m's new undergrad Kevin Kuns was introduced to 40m safety hazards. He is new and needs guidance as specially with 2W laser work.

Peter King will train him on Friday to LIGO-laser standard.

 

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