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ID Date Authorup Type Category Subject
  6420   Wed Mar 14 23:02:09 2012 KojiUpdateLSCLocking activity

Kiwamu and Koji

The target is to realize DRMI or PRMI + one arm with ALS.

The focus of the night is to achive stable lock of the PRMI (SB resonant) with 3f signals.
Particularly, REFL165 is back now, we are aiming to see if any of the 165 signals is useful.

We made a comparison between  REFL33Q/REFL165Q/AS55Q to find any good source of MICH.
However, none of them showed a reasonable shape of the spectra. They don't have reasonable coherence between them.

Nonetheless, we have tried to lock the IFO with those REFL signals. But any of them were useful to keep the PRMI (SB resonant).
The only kind of stable signal for MICH was AS55Q as we could keep the PRMI locked.

  6421   Thu Mar 15 04:04:23 2012 KojiConfigurationLockingPRC Matching issues

Kiwamu and Koji

We found that the intra-cavity mode of the PRC is not round although it was obvious even with the DARK and REFL port images.
We need to review the mode matching situation.

In order to look at the PRC intra-cavity mode, we reconfigured the POP CCD.

If we look at the beam reflected from the Michelson, the beam is round. However, the PRC intra-cavity mode can never be round
in any resonant conditions. (Pict 1, 2, and 3, for the sideband resonant, carrier resonant conditions and another carrier resonant
one, respactively). Particularly the mode of the carrier resonant case is very unstable and always changing.

P3150902.jpg

P3150906.jpgP3150907.jpg

By misaligning the PRM, we can compare between the spot directly reflected from the Michelson and the one after additional round trip in the PRC (Pic 4).

They looks round, but it was obvious the secondary reflection is dimmer and larger (Pic 5). The intensity difference corresponds to the factor RPRM RMI
(i.e. product of the reflectivities for the PRM and MI). It can be understand if the dimmer spot looks smaller due to the artifact of the CCD. But it is opposite.

This may mean the mode matching is not correct. We are not sure what is not right. This could be just an incorrect incident beam, the curvature error of the PRM,
beam is distortec by the TT mirrors, or some other unknown reasons.

More precise analysis can be done with quantitative analysis of those two spots with Beamscan. This could happen tomorrow.

P3150910.jpgP3150900.jpg

  6439   Thu Mar 22 23:43:56 2012 KojiUpdateCDSc1scx and c1scy not properly running

Did you guys checked if the simplant switch is set to "REAL WORLD" mode?

Edit by KI:

Bingo ! The input signals were bypassed to the simplant. I switched the simplant settings to REAL WORLD and now both end suspensions are working fine.

  6453   Tue Mar 27 17:19:02 2012 KojiUpdateIOOBeam Profile measurement: IPPOS beam

The mode looks quite terrible in the plot, but in reality it is an illusion of the plot.

The actual TEM00 content in this beam is ~99.7%


mode_coupling.pdf

Based on the above document, you can calculate power coupling between two elliptic gaussian modes.

Give the parameters of one beam as

zRy1 = pi*(2.77e-3)^2 / 1064e-9
z1y = 3.37
zRx1 = pi*(2.47e-3)^2 / 1064e-9
z1x = 4.15

Then, assume a round beam for the other.

zRx2 = zRy2 = zR
z2x = z2y = z0

Then run the optimizer to find the maximum for the quantity |C|^2

|C|^2 max: 0.9967
zR = 20.19
z0 = 3.804

  6455   Tue Mar 27 17:52:08 2012 KojiUpdateIOOAnother possibility / thought

It is quite likely that we touched the Faraday in Nov 2010.

In this entry http://nodus.ligo.caltech.edu:8080/40m/3874 I wrote that I removed the MCT optics in the chamber.
This is the pickoff between the IMC and the Faraday. This causes the beam shift. Therefore, the Faraday had
to be moved.

There were intensive in-chamber activities from Nov to Dec 2010. I am sure that almost everytime we went into
the chamber, we checked the spot position on the MMT mirrors as well as the TT and PZT mirrors.

Does the miscentering of the spots on the MMT mirrors cause the mode matching significantly changed?

  6588   Mon Apr 30 21:24:43 2012 KojiUpdateSUSETMY oplev power supply dead

And has the temp controller of the green been recovered too? (Push enable button)

 

  6595   Thu May 3 13:07:05 2012 KojiBureaucracyGeneralInterferometer check-up session

From 2PM, Jenne/Den/Koji. Finished at 10:30PM

  • General
    • More LCD screens! Wider screens!
      • Allegra - only can handle single head right now, but should prepare for the eventual upgrade of that videocard/whole computer and get 2 monitors.
      • Every workstation should have 2 24" monitors.  We currently have 2 good ones (one on Rossa, one on Pianosa), so we need 6.
    • Remove Control room shelf currently holding OSA 'scopes
    • Adjust both TV shelves so that they're at the same height, ~6" higher than the current left shelf.
      This gives space for stacking the 24" monitors for each computer.
    • Audio system for the signals!!!! Even a crappy one!
           /cvs/cds/ligo/centos5.5/cds/project/gds-2.14.2/Monitors/rockIFO
           /cvs/cds/gds/gds/Monitors/rockIFO
           (really /cvs/cds, not /opt)

  • IOO
    • PZT or Picomotor mounts for PSL/ALS beams
    • ALS on the both arm simultaneously / common/diff ALS scripts
  • SUS
    • PRM OPLEV servos are sometimes not stable. (fixed, JCD/DM/KA, 5/2/2012)
    • ETMX oplev - replace 1064nm lens with 632nm lens (KBC037, -100)
  • IFO
    • It seems that there is an occasional common-mode power transient in the arm transmissions.
      -> Track down the cause and fix.
    • Fix arm ASS even on CentOS
    • Drift of the green incident axis -> Assess the amount of the drift / replace the mount
    • Calibration of POP22 / AS110
    • PMC/IMC/ARM characterization (loss, finesse, reflectivity, etc)
  • CDS
    • Capture OSA signals in CDS (the 'scope TDS1001B has a USB port in the back for connecting to the computer)
    • Transmon (arms) for high and low power
    • POX11 whitening is not toggling the analog whitening???
    • CentOS machines cannot open simulink models properly (get "Bad Link"s everywhere, so you can't do anything useful).
    • Dataviewer and DTT can't connect to framebuilder from CentIOS machines
  • Electronics
    • Actuator noise level characterization (coil driver response in V/m & coil driver noise level V/rtHz)
    • Beat box
    • I/Q DFD
    • Improvement of POP22/110/AS110 RF circuits.
  • MEDM
    • OL alert in the watch dog screen (this is awesome!) should have small text saying "OL" (done, JCD, 5May2012)
    • Complete 40m overview screen - everything should be clickable with pseudo 3D icons
    • BETTER SUSPENSION SCREEN!!!
    • Script to generate a MEDM tree
    • Resurrect MEDM snapshots
       
    • The LSC screen has some "white" boxes -> investigate and fix them (done, KA, 5/2/2012)
    • Make the LSC control screen (compact) in the vertical arrangement (done, KA, 5/2/2012)
    • The signals of the watch dog screen should go red if any of the WDs are not enabled.
      =>Copy the logic of the signals in LSC screen.
      (done, KA, 5/2/2012)
    • Remove c1gfd from the cds status screen (done, KA, 5/2/2012)
    • Add "BURT" status indicators on the cds status screen (done, KA, 5/2/2012)
  • SCRIPT
    • Locking scripts with integrator triggers / disabling when unlocked
    • Daily diagnosis of the MC spot positions (there must be something already...)
    • Daily/occasional adjustment of the incident axis on the MC
    • Suspension "misalign/restore" script is too wild => make a new script (Done, JCD, 7May2012)
    • IFO_CONFIGURE scripts still do a burt restore, so step the optics.  Need to remove optic alignment from config .snap files, use reg restore script instead.
    • OPLEV/OSEM trending script before the IFO work for diagnosis.
    • Auto-locker for PMC/Arm/etc
  • Video
    • If each video screen has a caption, that would be great
    • GUI interface of "videoswitch" Mike!
    • Mouse Jiggler for Zita (called Swinput?)
  • Ubuntu
    • burttoday is not aliased in ubuntu. burttoday:      aliased to cd /opt/rtcds/caltech/c1/burt/autoburt/today/
    • ASS doesn't run on Ubuntu!
      ezcawrite: error while loading shared libraries: libca.so: cannot open shared object file: No such file or directory
      ezcaswitch: error while loading shared libraries: libca.so: cannot open shared object file: No such file or directory
       
  6598   Thu May 3 17:15:38 2012 KojiUpdateLSCc1iscaux2 rebooted/burtrestored

[Jenne/Den/Koji]

We saw some white boxes on the LSC screens.
We found c1iscaux2 is not running.

Once the target was power-cycled, these epics channels are back.
Then c1iscaux2 were burtrestored using the snapshot at 5:07 on 4/16, a day before the power glitch.

  6600   Thu May 3 21:13:48 2012 KojiSummarySUSITMX/PRM/BS OPLEV aligned

[Jenne/Den/Koji]

We locked Xarm/Yarm and manually alignmed ITMX/ITMY/BS/ETMX/ETMY/PZT1/PZT2.

ITMY OPLEV was largely misaligned ==> The beam was centered on the QPD.

----

Then we aligned PRM using SB locking PRMI.

We noticed that OPLEV servo does not work. It made the PRM just noiser.

We went into the PRM table and found that the OPLEV beam was clipped in the vacuum chamber.
We tried to maximize the reflected beam from the window by touching the steering mirrors at the injection side.

Then the reflected beam was introduced to the center of the QPD.

After the alignment, the OPLEV QPD SUM increased to 4000ish from 200ish.
According to the OPLEV trend data, this is a nominal value of the QPD SUM.

Now the OPLEV servo does not go crazy.

 --

BS OPLEV beam was centered on the QPD.

  6605   Sat May 5 09:13:02 2012 KojiUpdatePSLPMC

I suspect that it was just unlocked when you had disconnected the cable.

There is not reflection now. It seems that it is now misaligned after the alignment work.

So what you need is "align while scanning PZT -> lock -> align".

Quote:

Unfortunately, after the measurement when I unplugged BNS connector from the laser, I misaligned PMC. For several hours I adjusted the mirrors but could not significantly improve transmitted signal. I'll return to this issue tomorrow.

 

  6607   Sat May 5 12:23:38 2012 KojiUpdatePSLPMC

No matter how you connect/disconnect, touching the laser may cause the PMC unlocked.

At least, I don't see the PMC reflection on the PD.
This means that the beam towards the PMC is largely misaligned.

If you are not sure what is misaligned, stop touching the table.
Close the shutter of the laser on the laser housing and leave the optics as they are.

  6614   Mon May 7 19:39:52 2012 KojiUpdateIOOWFS noise in MC

OK. Then we should make this number bigger such that the coherence is still completely maintained.
Is this set in the auto locker? Or manually set?

Quote:

  This effect is due to C1:IOO-WFS1_PIT_LIMIT=2000. When I turned if off, coherence between C1:IOO-WFS_PIT input and output signals restored

 

  6631   Wed May 9 09:19:22 2012 KojiUpdateLockingPRM is really moving when PRMI locked

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

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

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

  6637   Thu May 10 14:49:06 2012 KojiHowToGeneralHow to clean & bake black glass pieces

  6653   Mon May 21 19:16:55 2012 KojiUpdateGeneralrossa X config

I rebooted rossa and the X sever has stalled.

  6675   Thu May 24 14:49:59 2012 KojiSummaryGeneralDaily news idea

Top tab categolies:

  • Summary
  • CDS
    • CDS Status
  • PEM
    • Seismic 24h trend
    • Accoustic 24h trend
    • Weather/Temp/Barometer/etc 24h trend
  • PSL/IOO
    • PSL summary trend / duty ratio
    • IOO summary (MC Health Check/IOO QPD trends / IFO QPD trends / Transmon QPD trends) duty ratio
  • SUS
    • Summary
    • OSEM PSD/trend
    • OPLEV PSD/trend
  • IFO
    • DC Mon
    • RF ports
    • OMC
  • Steve
    • Vacuum
  • Misc.

IFO

  • DC Monitors
    • Incident beam power trend (24h)
    • AS/REFL/POP/TRX/TRY bean power trend (24h)
    • AS/POP RF beam power trend (24h)
  • RF port
    • DARM sensitivity PSD (mean/min/max/reference) for an hour
    • DARM/CARM/PRCL/MICH/SRCL PSD
    • DARM/CARM/PRCL/MICH/SRCL (freq vs Gaussianity)
    • DARM/CARM/PRCL/MICH/SRCL calibration trend
  • OMC
    • TBD

 

  6682   Fri May 25 16:10:53 2012 KojiUpdateGeneralStripTool on Zita restored

ssh -X pianosa

On pianosa

StripTool PSL.strip&
StripTool IOO.strip&
StripTool seismic.strip&

 

  6690   Sat May 26 01:28:58 2012 KojiUpdateGeneralClipping improvement

The beam at the dark port was largely clipped.
The arm transmissions (TRX/TRY) were ~0.6 no matter how you try to align.

The PZT1/2 X was scanned and TRX/TRY are now both ~0.9.
This means that the beam was mostly clipped in or after the mode mathing optics.

FPMI contrast is (2.45-0.02)/(2.45+0.02) = 98%
Not so bad although it does not tell anything about clipping before the IFO.

In the next opportunity, we should try to "pin" the beam axis on the arm mirrors using A2L.

1. I am not sure exactly where the clipping was. It means that a small clipping might still be there.

2. I am afraid that the beam is still clipped in the faraday. The beam can be scanned using the steering on the PSL table.

 

Attachment 1: Untitled.png
Untitled.png
  6704   Tue May 29 15:48:31 2012 KojiUpdateIOOPMC, MC alignment are shit

The followings are a kind of daily check. Do this without any notice:

- Align PMC.

- Check MC spot position with the script (where is it located?). Ignore MC2 result as it can be arbitrary set.

- If the MC1/MC3 spots have moved it means that the PSL beam has moved. If the beam has moved, we should have some discussion what we should do.

- If the spot positions are about the same as before, align the MC mirrors. This should be done by nulling the WFS feedback. (Someone should make a simple script for this WFS offloading.)

------------

Then, start locking both arms

Quote:

[Yuta, Jenne]

PMC and MC alignment are both shit, although with the WFS on, the MC is pretty good.  We're leaving it for now, so that (a) we don't mess up Koji's work, and (b) we can work on the Xarm.  Steve is doing Yarm oplev stuff, so we'll do Yarm later.

 

  6705   Tue May 29 15:49:02 2012 KojiUpdateLockingETMX trans camera

Quote:

...will be helpful for acquiring lock after the vent.  We should install a camera at ETMX.

 Do that.

  6780   Thu Jun 7 07:27:27 2012 KojiUpdateGreen Lockingimproved Y arm green alignment - even more

Yes. The end PDH servo should be checked more carefully.

The end PDH seems to have insufficient gain at around 100Hz.
The attached is the ALS noise budget calculated with the simulink model for the green locking paper.

The residual error of the end AUX laser (green) is contributing to the final ALS signal (black).
In particular, the residual AUX frequency noise, which is shown as the blue, is contributing to the noise above 100Hz.

In the model I also confirmed that the servo still has a room for improvement.

By having more suppression of the AUX frequency noise, we will be able to increase the ALS servo bandwidth
without increasing the ALS residual RMS by a servo bump. This will give us the improvement of the seismic
noise suppression at 10Hz (i.e. more suppression of red).

Attachment 1: freq_noise_AUX.pdf
freq_noise_AUX.pdf
  6786   Thu Jun 7 13:25:37 2012 KojiUpdateSUSPRM is still oscillating

Done.

C1:SUS-PRM_OLPIT_GAIN 1.0 -> 0
C1:SUS-PRM_OLYAW_GAIN -0.7 -> 0
 

Quote:

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

 

  6820   Fri Jun 15 01:53:05 2012 KojiUpdateGreen Lockingscanned Y arm for 5FSR

Interesting. It seems for me that there is a dependence of the noisiness as the beat frequency is scanned.

As you increase (or decrease?) the offset, C1:ALS-BEATY-COARSE_I_IN1 becomes bigger and more crisp.
The resulting out-of-loop stability also seems to be improved as you can see from the crispness of the PDH signal.

Do you find why this happens? Is this because the beat S/N depends on the beat frequency due to the PD noise?

 

  6826   Sat Jun 16 18:51:44 2012 KojiUpdateGreen LockingY arm length using 5FSR scan

Quote:

Calibrating beat frequency to Y arm length change;
  I used L = 32.36 m (figure above, bottom plot).
    dnu_g / dL = c / lamb_g / L = 1.74 MHz/m

Wow. This is way too short.

You don't need to use Albertoo's arm length as his measurement was done before the upgrade.

  6852   Fri Jun 22 03:37:42 2012 KojiUpdateGreen Locking2 arm ALS - Success!!!!

Are these correct?

1. It is a nice work.

2. This is not locking, but stabilization of the both arms by ALS.

3. We now have the phase trackers for both arms.

4. There is no coarse (i.e. short) delay line any more.

5. The splitters after the PDs are reducing the RF power to Beat-box.
Actually there are RF monitors on Beat-box for this purpose, but you did not notice them.

6. c1ioo channel list
https://wiki-40m.ligo.caltech.edu/CDS/C1IOO%20channel%20list
has to be updated.

7. Video can be uploaded to Youtube as Mike did at http://nodus.ligo.caltech.edu:8080/40m/6513

  6870   Mon Jun 25 16:21:10 2012 KojiSummaryIOOSelection of motorized mirror mounts

I am considering to have 3 to 6 motorized optical mounts at the PSL and end tables for remote beam steering.

Question 1:

Was there any issue on the PI 3-axis PZT on the PSL?
Why was it disabled (even before the PSL upgrade)?


Question 2:

Do we need two mount at a place? Or we do have one instead?

- Comparing the distance of the steering mirrors and that from the steering mirror to the cavity waist, induced shift
is mostly cancelled by angle adjustemnts of a either of the mounts.
i.e. Induced misalignments by the steering mirrors are nearly degenerated.

We need to move two steering mirrors only for the initial installation, but any drift felt by a cavity can be compensated by a single mirror.

Question 3:
Do we like PI-style 2 or 3 axis PZT mount with analog inputs on the HV amp?
Or do we like "Newport Agilis" style controller with USB connection?

Any opinion?

  6887   Thu Jun 28 01:44:57 2012 KojiUpdateLockingPRMI work started, commissioning plan

To be fair, this is Kiwamu's idea. And nothing is reasonable before it is confirmed quantitatively.

Quote:

Koji's idea of flipped-PRM seems reasonable, so I think we should better measure something to prove this.

  6939   Sun Jul 8 00:58:08 2012 KojiSummaryLockingcalibrating phase tracking mode scan data

Quote:

FSR for X/Y arm are 3.97 +/- 0.03 MHz and 3.96 +/- 0.02 MHz respectively. This means X/Y arm lengths are 37.6 +/- 0.3 m and 37.9 +/- 0.2 m respectively.

These aren't so bad. (Look at this entry)

And interestingly the ETM curvatures are closer to ATF measurements than Coastline's measurement. (Look at wiki)

  6949   Tue Jul 10 01:52:47 2012 KojiUpdateLSCPRMI got more stable a bit

The phase margins looks still too small.

Do You need such high gain at LF? This is not a high finesse cavity so can we sacrifice
some DC gain while gaining more phase around UGFs?

Otherwise, the gain fluctuation should be nicely compensated (i.e. fancy normalization).

  7009   Mon Jul 23 19:00:26 2012 KojiUpdateGreen LockingALS_END.mdl model added for end station green ALS channels

This is a good modification. We just need to check how the ALS scripts are affected.

Quote:

The end sus models (c1scx and c1scy) both contain some ALS stuff.  This stuff could maybe be moved to their own models, but whatever.

The stuff at X and Y were identical, but were code copies (BAD!).  I made a new library part for the ALS end controls: ${userapps}/isc/c1/model/ALS_END.mdl

It contains just some filter modules for the ALS end laser control, and a monitor of the ALS end REFL PD DC.  I also added a DQ block for the recorded channels (see screen shot).

When I added this new part to c1scx and c1scy I made it so the channel names would be more sensible.  Instead of "GCX" and "GCY", they are now "ALS-X" and "ALS-Y".  They will now all show up under the ALS subsystem.

 

  7033   Wed Jul 25 22:16:36 2012 KojiUpdateLSCringdown measurement

Is this the step response of the single pole low pass???
It should have an exponential decay, shouldn't it? So it should be easier to comprehend the result with a log scale for vertical axis...

I think you need a fast shutter. It is not necessary to be an actual shutter but you can use faster thing
which can shut the light. Like PMC or IMC actuators.

Another point is that you may like to have a witness channel like the MC transmission to subtract other effect.

  7061   Tue Jul 31 19:34:55 2012 KojiUpdateSTACISOpen loop gains and block diagram

With your definition of the open loop gain, G=+1 is the condition to have singularity in a closed loop transfer function 1/(1-G).

But this is not the sole criteria of the loop stability.
Basically, the closed loop transfer function should not have "unphysical" pole.
For more about loop instability, you should refer stability criteria in literature such as Nyquist's stability criterion.

Both of the X and Z loops look unstable with the current gain.

  7120   Wed Aug 8 13:37:46 2012 KojiUpdateComputer Scripts / ProgramsWeek 8/Summary Pages update

Hey, the pages got significantly nicer than before. I will continue to give you comments if I find anything.

So far: There are many 10^-100 in logarithmic plots. Once they are removed, we should be able to see the seismic excitation during these recent earth quakes?

Incidentally, where the script is located? "./" isn't the absolute path description.

Quote:

Over the past week, I have been working on my progress report and finalizing the summary pages.  I have a few more things to address in the pages (such as starting at 6 AM, including spectrograms where necessary and generating plots for the days more than ~a week ago) but they are mostly finalized.  I added all of the existing acoustic and seismic channels so the PEM page is up to date.  The microphone plots include information about the transfer factor that I found on their information sheet (http://www.primomic.com/).  If there are any plots that are missing or need editing, please let me know!

I also modified the c1_summary_page.sh script to run either the daily plots or current updating plots by taking in an argument in the command line.  It can be run ./c1_summary_page.sh 2012/07/27
 or ./c1_summary_page.sh now to generate the current day's pages.  (Essentially, I combined the two scripts I had been running separately.)  I have been commenting my code so it is more easily understandable and have been working on writing a file that explains how to run the code and the main alterations I made.  The most exciting thing that has taken place this week is that  the script went from taking ~6 hours to run to taking less than 5 minutes.  This was done by using minute trends for all of the channels and limiting the spectrum plot data.

The summary pages for each day now contain only the most essential plots that give a good overview of the state of the interferometer and its environment instead of every plot that is created for that day.

I am waiting for Duncan to send me some spectrogram updates he has made that downsample the timeseries data before plotting the spectrogram.  This will make it run much more quickly and introduce a more viable spectrogram option.

 

Today's Summary Pages can be accessed by the link on the wiki page or at:

https://nodus.ligo.caltech.edu:30889/40m-summary/archive_daily/20120808/

 

  7124   Wed Aug 8 20:50:39 2012 KojiUpdateASSTrouble measuring sensing matrix

From the log, I couldn't understand what has been done.

The procedure we should perform is

  1. Dither total 4 dofs of the two mirrors with different frequencies. Some fluctuation of TRY is even visible in dataviewer.
  2. The cavity is aligned at the beginning. These 4 peaks in TRY in DTT is small or invisible. Some 2nd harmonics are visible.
  3. Misalign one of the dofs. Some peaks get bigger.
  4. Correspoding lockin output becomes bigger.

Then you can start measuring the sensing matrix. At which part did the attempt fail?

Quote:

I turned on the ASS, without closing the loops, to try to measure the sensing matrix. 

The Yarm was locked (Eric did a nice job earlier - he'll ELOG ABOUT IT before he goes home!), and I used an LO CLKGAIN of 300 on all of the TRY Lockins.  Then I put on and took away a 10% offset in pitch, but it's almost impossible to see the difference. 

The attached is a truly awful screenshot, but you can kind of see what's going on.  The big steps are me increasing the LO gain, but around "0" on the x-axis I changed the pitch offset from 10% away to nominal.  Since there are such big oscillations, the change is basically non-existent.  Grrrr. I'll look at it again tomorrow, since I have an exiting bike ride home ahead of me....

 

  7131   Thu Aug 9 01:26:03 2012 KojiUpdateASSTrouble measuring sensing matrix

That's a good point, but I suspect that you end up with the in-phase (0deg) as the response of the IFO is immediate compared with the dithering frequency
as long as the whitening/dewhitening are properly compensated in the digital realm.

Quote:

 Okay, so this is a little stream-of-consciousness-y, and you're going to think I'm really dumb, but I just realized that I haven't set the phase of the lockin demodulators yet.  So I think I need to dither the optics, and go through each of the sensors, and adjust the phase until the peak in TRY in DTT is maximized for the I phase, and minimized for the Q phase (since we use the I-output).  Bah.  Bad Jenne.

 

  7155   Sun Aug 12 10:34:45 2012 KojiUpdateSAFETYexit door left unlocked

I unlocked the door on Tuesday in order to move the red cart.
After that I confirmed that the door was locked.

Quote:

Caltech security called me at 1am Sunday. Control room emergency exit door was found unlocked!

It is your responsibility to lock door if you unlocked it ! 

 

  7158   Mon Aug 13 09:59:05 2012 KojiUpdateGeneralMysterious banging on emergency door

You mean 5000?

Quote:

Probably, security. You can call 5555 and ask them. Otherwise you can ask them to come and check everything.

 

  7216   Fri Aug 17 09:34:27 2012 KojiUpdateCamerasvideo cameras in the dark
I used the LED illuminations at ETMX and BS yesterday for a tour.
I am afraid that I left them on.
  7264   Thu Aug 23 22:41:04 2012 KojiUpdateIOOMC Autolocker update

[Koji Rana]

MC Autolocker was updated. (i.e. mcup and mcdown were updated)

mcup:

  • Turn on the MCL input and output switches
  • Change the MCL gain from 0 to -300 with nominal ramp time of 5sec
  • Turn on FM2, FM5, MF7 after a sleep of 5sec. Note: FM1 FM8 FM9 are always on.
  • Set the offset of 42 counts
  • Turn on the offset

# Turn on MCL servo loop
echo mcup: Turning on MCL servo loop...
date
ezcaswitch C1:SUS-MC2_MCL INPUT OUTPUT ON
ezcawrite C1:SUS-MC2_MCL_GAIN -300
sleep 5
ezcaswitch C1:SUS-MC2_MCL FM2 FM5 FM7 ON
# Offset to take off the ADC offset of MC_F
ezcawrite C1:SUS-MC2_MCL_OFFSET 42
ezcaswitch C1:SUS-MC2_MCL OFFSET ON


This offset of 42 count is applied in order to compensate the ADC offset of MC_F channel.
The MCL servo squishes the MC_F signal. i.e. The DC component of MC_F goes to zero.
However, if the ADC of MC_F has an offset, the actual analog MC_F signal, which is fed to FSS BOX,
still keep some offset. This analog offset causes deviation from the operating point of the FSS (i.e. 5V).

mcdown:

  • Basically the revese process of mcup.
  • This script keeps FM1 FM8 FM9 turned on.

# Turn off MCL servo loop
echo mcdown: Turning off MCL servo loop...
date
ezcawrite C1:SUS-MC2_MCL_GAIN 0
ezcaswitch C1:SUS-MC2_MCL INPUT OUTPUT OFFSET FMALL OFF FM1 FM8 FM9 ON
# Remove Offset to take off the ADC offset of MC_F
ezcawrite C1:SUS-MC2_MCL_OFFSET 0

  7265   Thu Aug 23 22:44:32 2012 KojiUpdatePSLFSS Slow DC servo is turned off (not temporary)

[Koji Rana]

The FSS Slow DC servo was turned off.

As MCL stabilizes the MC_F (Fast PZT), we no longer need to use the laser temp to do so.

In other word, if you like to turn off the MCL servo for some reason, we need to turn it on in order to keep the MC locked.

  7273   Fri Aug 24 20:48:10 2012 KojiUpdatePSLPMC aligned

as usual.

  7274   Fri Aug 24 21:00:40 2012 KojiUpdateLSCX end green investigation

I checked and fixed the X end green situation. Now the X green beam is locked with TEM00.

There are various reasons it did not lock nicely.

  • The IR beam axis was changed by Yoichi and Rana (ELOG #7169). So the green axis also had to be changed.
  • The end green optics is really "BS". Anytime I see it, I feel disgusted. Because of 3D steering mirrors, cross couplings
    between yaw and pitch are big. This makes the alignment hard.
  • Even with acceptable alignment, the lock was only momentarily. I found the slow control was on. This pushed the frequency
    too much and made the lock unstable.
  • The slow control screen was broken as Jamie changed the model names but did not fix the slow screens.
    • Jamie saids (ELOG #7011): Fix the c1sc{x,y}/master/C1SC{X,Y}_GC{X,Y}_SLOW.adl screens. 
      I need to figure out a more consistent place for those screens.

Now some action items are left:

- IR TRX is not aligned.
- X end green needs precise alignment.
- PSL GR TRX is not aligned.

These will be checked on Sunday.

- End green setup is horrible. => Manasa and I should work on this together.

  7279   Sun Aug 26 21:47:50 2012 KojiUpdateCDSC1LSC ooze

I came in to the lab in the evening and found c1lsc had "red" for FB connection.
I restarted c1lsc models and it kept hung the machine everytime.

I decided to kill all of the model during the startup sequence right after the reboot.
Then run only c1x04 and c1lsc. It seems that c1oaf was the cause, but it wasn't clear.

  7283   Mon Aug 27 10:49:03 2012 KojiUpdateSUSEQ damage

After shaking ITMX by the alignment bias in yaw, it came back.

As ETMX seems to be largely misaligned yaw (and did not come back with the alignment impact),
the condition of the magnets are not clear. Only the side OSEM is responding nicely.

Quote:

  It looks like we may lost 1 (or 3 )  magnets? Do not panic, it's not for sure

 

  7284   Mon Aug 27 12:03:54 2012 KojiUpdateIOOMC spot position - callin' it quits

The MC REFL path was checked. ==> Some clippings were fixed. MC WFS is working now.

- MC was aligned manually

- The steering mirror for the WFS and camera was clipping the beam. => FIxed

- The WFS spots were realigned.

- There was small clipping on the MC REFL RFPD. ==> Fixed

  7302   Tue Aug 28 19:06:32 2012 KojiMetaphysicsRingdownripples

Isn't it just a ringing of the intracavity power as you shifted the laser frequency abruptly?

Quote:

Let's see if the ripples observed in the MC ringdown can be due to tilt motion of the mirrors.

The time it takes to produce a phase shift corresponding to N multiples of 2*pi is given by:

t = sqrt(2*N*lambda/(L*omega_T^2*(alpha_1+alpha_2)))

L is the length of the MC (something like 13m), and alpha_1, alpha_2 are the DC tilt angles of the two mirrors "shooting into the long arms of the MC" produced by the MC control with respect to the mechanical equilibrium position. omega_T is the tilt eigenfrequency of the three mirrors (assumed to be identical). lambda = 1.064e-6m;

The time it takes from N=1 to N=2 (the first observable ripple) is given by: tau1 = 0.6/omega_T*sqrt(lambda/L/(alpha_1+alpha_2))

The time it takes from N=2 to N=3 is given by: tau2 = 0.77*tau1

etc

First, we also see in the measurement that later ripples are shorter than early ripples consistent with some accelerated effect. The predicted ripple durations tau seem to be a bit too high though. The measurements show something like a first 14us and a late 8us ripple. It depends somewhat on the initial tilt angles that I don't know really.

In any case, the short ripple times could also be explained if the tilt motions start a little earlier than the ringdown, or the tilt motion starts with some small initial velocity. The next step will be to program a little ringdown simulation that includes mirror tilts and see what kind of tilt motion would produce the ripples exactly as we observe them (or maybe tilt motion cannot produce ripples as observed).

 

  7304   Tue Aug 28 20:23:54 2012 KojiMetaphysicsRingdownripples

Laser frequency shift = longitudinal motion of the mirrors

Ringing: http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-20-24-2463

Quote:

Hmm. I don't know what ringing really is. Ok, let's assume it has to do with the pump... I don't see how the pump laser could produce these ripples. They have large amplitudes and so I always suspected something happening to the intracavity field. Therefore I was looking for effects that would change resonance conditions of the intracavity field during ringdown. Tilt motion seemed to be one explanation to me, but it may be a bit too slow (not sure yet). Longitudinal mirror motion is certainly too slow. What else could there be?

 

  7310   Wed Aug 29 17:35:34 2012 KojiUpdatePSLPower reduced!

The biggest reason why we could not lock the MC was that the beam was not properly hitting the MC REFL diode.

Now the MC REFL DC is about ~0.1 and 1.2 when the MC is and is not locked.

We increased the power according to the quantitative analysis of the intracavity power in this earlier entry

Autolocker script for the low power MC was modified so that the initial VCO gain is 3 in stead of 10.
The 2 steps of super boost were also enabled again.

  7312   Wed Aug 29 20:43:23 2012 KojiUpdateIOOSetup for a cavity scan or the input mode cleaner

The technique is based on detection of the beating between the resonant carrier and a resonant higher order mode.
This means that the beat signal is cancelled out if the transmitted beam is integrated over the entire beam.
Thus, you may want to introduce intentional clipping (or cutting a half of the beam with a razor blade). 

Ref: LIGO DCC G080467: Precise Measurements on Longitudinal and Transverse Mode Spacings of an Optical Cavity using an Auxiliary Laser

I am quite curious on the measurement as I am going to do the same measurement for the aLIGO OMC.
I am interested in seeing the statistical evaluation on the precision of the measurement.

  7332   Fri Aug 31 18:32:47 2012 KojiUpdateIOOCorrecting improper termination of the 55MHz input to the EOM

 

The power switch of the frequency source was mechanically broken. I replace it with the spare in Kiwamu's treasure box.
I think this replaced new one also had the same problem before, we basically have to find an alternative switch.
The problem is too much friction between the metal housing and the plastic button. I have lubricated the button with
bicycle oil.

I have checked that the 55MHz output still have the output of 25dBm after a 5m BNC cable. (nominal: 27dBm)

I could not test it with the MC as the chambers have already been closed with the light doors.

ELOG V3.1.3-