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ID Date Author Type Categoryup Subject
  8288   Wed Mar 13 16:25:16 2013 ManasaUpdateIOOTuning MC length/FSR

[Koji, Manasa]

We looked at the MC modulation frequency on the spectrum analyzer and observed beat notes between MC modulation freq (29.5MHz) and modulation frequencies (11.06 MHz and 55.3MHz).

Beat notes were suppressed by changing the carrier frequency from 11.065910 MHz to 11.066147MHz. 

Detailed discussion and data will be posted in the next elog.

  8343   Mon Mar 25 23:17:11 2013 ranaSummaryIOOMC

I measured the dark noise and regular intensity noise in MC trans tonight to get some estimate for the free running spectrum that the Chas ISS must overcome. PDF is attached.

XML file is /users/rana/dtt/MC-trans_130325.xml

The RIN normalization was done by using the mean of the SUM time series. The dark noise was measured by misaligning MC2 and making the same measurement with the bright normalization.

  8349   Tue Mar 26 01:40:49 2013 KojiUpdateIOOTuning MC length/FSR

I'm still waiting for the follow-up analysis of the modulation freq tuning.

  8353   Tue Mar 26 15:00:55 2013 ManasaUpdateIOOTuning MC length/FSR

Quote:

[Koji, Manasa]

We looked at the MC modulation frequency on the spectrum analyzer and observed beat notes between MC modulation freq (29.5MHz) and modulation frequencies (11.06 MHz and 55.3MHz).

Beat notes were suppressed by changing the carrier frequency from 11.065910 MHz to 11.066147MHz. 

Detailed discussion and data will be posted in the next elog.

The goal was to tune the carrier modulation frequency, f1 ~ 11.06 MHz to match the FSR  (c/2L) of the MC. (Reference to the technique: R.G.DeVoe et al., PRA 30, 5, Nov 1984)

We looked at the MC_REFL output on the spectrum analyzer. Since the MC FSR was not well matched with the carrier modulation frequency, we observed significant beat notes at the following frequencies (fMC-f1),  (fMC+f1), (fMC-f2) and (fMC+f2); where fMC (the MC modulation frequency) = 29.5MHz, f1(carrier modulation frequency) ~ 11.06MHz and f2 ~ 55.3MHz. The carrier modulation frequency was changed at the frequency generator until these beat notes were suppressed i.e. until the cavity FSR matched the carrier modulation frequency.

The plot below shows the MC spectrum after the beat notes were suppressed.

MC_spectrum.png

  8354   Tue Mar 26 15:43:45 2013 ranaUpdateIOOTuning MC length/FSR

  Please attach the data file of the measurement - its hard to get the real information out of picture. In general, WE should always include the code / explanation of how to reconstruct the plot and get the scientific information out.

  8357   Tue Mar 26 17:27:17 2013 KojiUpdateIOOTuning MC length/FSR

Please add the discussions on the cavity absolute length (and its change, adjustment precision),
identification of the peaks, before/after comparison of the plot, the effect of the MC REFL PD response,
and comparison of the cavity linewidth vs deviation of the 55MHz SBs from the resonance.

  8426   Tue Apr 9 00:32:39 2013 ranaConfigurationIOOTurn on MCL

 Listening to the free swinging Y-arm, its clear that the fringe velocity is higher with the MCL path off, than on. I checked that the default gain of -300 was too high and changed it to -100 in the mcup script. With the higher gain value, there was clear gain peaking at just under 60 Hz (where the 60 Hz comb filter starts). We basically want the UGF to be between 20 and 60 Hz so that we can have the Bounce mode RG at 16.25 Hz and also the notch filter at 60 Hz.

Den is measuring and setting the UGF to be ~45 Hz.

With the MCL path on there is a high frequency horn-like noise in the Yarm when it locks. Its reduced a little by reducing the loop gain, but clearly this is just noise introduced by the MCL loop as Den noted before (and also tonight). He is cleaning up the whole MCL MEDM situation so that its useable by us. At the moment I've re-enabled it in the mcup.

My belief is that the frequency noise from the unstabilized MC is making the PRC locking harder. This will be investigated by tuning the shape of the MCL/MCF crossover so that we can turn it on without ruining the arm cavity spectra. Since the PRC length is ~2x smaller than the MC, we would expect it to be less sensitive to the MC frequency noise. But, since there is some common mode rejection in there, this may not be true. We'll only know by measuring PRC control signal with MCL on/off.

  8434   Wed Apr 10 03:59:41 2013 DenConfigurationIOOTurn on MCL

Quote:

 My belief is that the frequency noise from the unstabilized MC is making the PRC locking harder. This will be investigated by tuning the shape of the MCL/MCF crossover so that we can turn it on without ruining the arm cavity spectra. Since the PRC length is ~2x smaller than the MC, we would expect it to be less sensitive to the MC frequency noise. But, since there is some common mode rejection in there, this may not be true. We'll only know by measuring PRC control signal with MCL on/off.

 I think if we make MCL UGF higher then 20 Hz, arm cavity spectra will feel it. It might be possible to use a combination of feedback and feedforward control from ground seismometers. I made MCL UGF at 3 Hz to reduce 1 Hz motion of the pendulum; feedforward OAF subtracted the stack at 3.3 Hz. Once OAF converged, I blocked adaptation and the filter became static FIR. MC length RMS was reduced by a factor of 10 and arm cavity spectra was not affected at frequencies >20 and became better at low frequencies. We'll see if this enough.

On the attached plot red color shows MC_F with MC_L OFF, blue - MC_L is ON, green - MC_L and OAF are ON.

Then I locked PRCL (using AS_Q and REFL55_I) to carrier and aligned the cavity. Power RIN was 50-70% and 00 beam on the POP camera was moving significantly. BS oplev was shaking the optics at 5 Hz. I fixed it, but there should be something else as RIN was still high.

  8469   Mon Apr 22 11:46:09 2013 KojiSummaryIOOMC locked/aligned. MC WFS offloading by ezcaservo

Еру ьс шы тщц дщслув фтв фдшптувю

Фдыщ ш кфт еру ащддщцштп ыскшзе ещ щаадщфв еру ЬС ЦАЫ ыукмщю

I blame Den for russian keyboard installation on the control machines.

ezcaservo -r 'C1:SUS-MC2_ASCPIT_OUT16' -g '0.00001' -t 60 C1:SUS-MC2_PIT_COMM&
ezcaservo -r 'C1:SUS-MC2_ASCYAW_OUT16' -g '0.00001' -t 60 C1:SUS-MC2_YAW_COMM&
ezcaservo -r 'C1:SUS-MC1_ASCPIT_OUT16' -g '0.00001' -t 60 C1:SUS-MC1_PIT_COMM&
ezcaservo -r 'C1:SUS-MC1_ASCYAW_OUT16' -g '0.00001' -t 60 C1:SUS-MC1_YAW_COMM&
ezcaservo -r 'C1:SUS-MC3_ASCPIT_OUT16' -g '0.00001' -t 60 C1:SUS-MC3_PIT_COMM&
ezcaservo -r 'C1:SUS-MC3_ASCYAW_OUT16' -g '0.00001' -t 60 C1:SUS-MC3_YAW_COMM&

  8471   Mon Apr 22 17:06:42 2013 ranaSummaryIOOMC locked/aligned. MC WFS offloading by ezcaservo

 

 Why use the PSL beam as a reference? Don't we want to keep the MC pointing in a good direction through the Faraday instead???

  8530   Mon May 6 19:04:30 2013 JamieUpdateIOOmode cleaner not locking

About 30 minutes ago the mode cleaner fell out of lock and has since not been able to hold lock for more than a couple seconds.

I'm not sure what happened.  I was in the middle of taking measurements of the MC error point spectrum, which included adjusting the FAST gain.  I've put all the gains back to their nominal levels but no luck.  I'm not sure what else could have gone wrong.  Seismic noise looks relatively quiet. 

  8531   Mon May 6 21:05:06 2013 rana, Jamie, KOjiUpdateIOOmode cleaner not locking

As it turned out, the setting of +26dB for the FSS Fast gain was making the NPRO PZT / Pockels cell crossover too unstable. This was the cause of the large ~30 kHz peak that Jamie was seeing in his spectra (more to follow in the morning).

After recovering the locking, etc. by fiddling with the gains, we went about systematically setting all of the gains/offsets. Jamie's elog will show all of the various spectra with different FSS gains.

For offset setting, this was the procedure:

  1. We want the MC servo board to have zero voltage on its MCL and MCF outputs (aka MC_SLOW_MON and MC_FAST_MON) with the Boosts ON, so we switched ON the 40:4000 and the 2 Super Boosts and put the VCO gain into its nominal +25 dB setting. This saturates the outputs and makes them impossible to use as readbacks so you have to be careful. Get the outputs close to zero as you turn on each boost. Finally, you will see that +/- 1mV of input offset (aka MC_REFL_OFFSET) will flip the FAST output between +/- 10V. This is the right setting.
  2. With the MC board adjusted to send 0 V into the FSS error point, adjust the FSS input offset (with the Common and Fast gains at the nominal values) so that the FAST output voltage goes to +5.5 V. This is the middle of the range for the high voltage driver which drives the NPRO.
  3. Let the MC lock and go through the UP script. When the MCL comes on with the integrator, the FAST voltage will shift from +5.5 V to something else. Use the following line: ezcaservo -r C1:PSL-FSS_FAST -g -1 -s 5.5 C1:SUS-MC2_MCL_OFFSET, to automatically tune the MCL offset.

     

    That's all. I have left the FSS common gain at +10.5 and the Fast gain at +23.5. These seem to be close to the optimum. Jamie will have more tuning tomorrow.
     
    I have also changed the 'mcup' script to set the MCL offset and set the FSS Slow setpoint to shoot for +5.5 V of FSS_FAST.
     
    MC_REFL_OFFSET = +1.176 V
    MC2_MCL_OFFSET = +47.8 counts
    FSS_INOFFSET   = -0.85 V
  8534   Tue May 7 03:25:28 2013 JenneUpdateIOOMC WFS drifting??

I'm not sure why, but starting ~3.5 hours ago, the WFS seem to not be holding the MC in optimal alignment. 

The WFS are definitely engaged and the loops are closed, but every time the MC locks, the WFS pitch and yaw values start drifting off.  In particular, the WFS loop actuation pushing on MC2 is in the many hundreds of counts after ~90 minutes of drift time.  I tried offloading those values by moving the MC2 slider, but then I unlocked the MC to check what that did to the alignment, and it was decidedly bad.  So, I'm not sure what's up with the WFS, but I need to look at it tomorrow.

  8575   Tue May 14 20:30:29 2013 JamieSummaryIOOMC error spectrum at various FSS gain settings.

I used the Agilent 4395A and the GPIB network bridge to measure the MC error spectrum at the MC servo board.

I looked at various settings of the FSS Common and FAST gains.

Here is the spectrum of various Common gain settings, with a fixed FAST setting of 23.5:

f23.5.pdf

The peak at 34k is smallest at the largest Common gain setting of 13.0 (probably expected).  The other higher frequency peaks are higher, though, such as the ones at 24.7k, 29.6k, 34.5k, etc.:

f23.5z1.pdf

Here's a blow up of the peak at 1.06M, which peaks at about 9dB of common gain:

f23.5z2.pdf

 Here's the spectrum with a fixed Common gain of 10.5, and various FAST gains:

c10.5.pdf

and here's a zoom around that 1.06 MHz peak, which is smallest at a FAST gain of 23.5 dB:

c10.5z1.pdf

I'm not sure yet what this points to as the best gain settings.  We can of course explore more of the space.  I'm going to leave it at 13/23.5, which leaves the PC RMS at ~1.5 and the FAST Monitor at ~6.0.

If this does turn out to be a good setting we'll need to adjust some of the alarm levels.

Various settings:

MCS
  in1 gain: 15
  offset: 1.174
  boost enabled
  super boost: 2
  VCO gain: 25

FSS:
  input offset: -0.8537
  slow actuator: 0.6304

I include the python scripts I used to remotely control the AG4395 to take the measurements, and make the plots.

PS: I made some changes/improvements to the netgpib stuff that I'll cleanup and commit tomorrow.

 

  8587   Thu May 16 01:41:31 2013 JenneSummaryIOOFSS gain settings set

Quote:

I'm not sure yet what this points to as the best gain settings.  We can of course explore more of the space.  I'm going to leave it at 13/23.5, which leaves the PC RMS at ~1.5 and the FAST Monitor at ~6.0.

 I changed the value of the nominal FSS common gain in the PSL Settings screen (It's called the 'FSS global gain' there).  To get to this screen:  sitemap -> PSL_main -> PSL_settings.  The MC autolocker reads these settings from the screen and uses those values.  Now the FSS returns to this value of 13 that Jamie has chosen.  For the past few days, it's been going back to the old value of 10.1 .  The FAST gain was already set to this 23.5 value.

  8627   Thu May 23 10:48:42 2013 ManasaUpdateIOOMC autolocker and MCWFS enabled

Some strong seismic noise (not related to any earthquakes - watchdogs are all green) had got the MC unlocked this morning.

I found the MC autolocker and MCWFS disabled. Enabling them locked the MC right away. I don't see any updates in the elog  as to why these were left disabled and hence have left them ON now.

  8647   Tue May 28 11:11:37 2013 ManasaUpdateIOOMC aligned

[Jenne, Manasa]

Fixed crappy alignment of MC by moving MC mirrors. MC REFL PD measured 0.5 after alignment. Spot positions were measured using msassMCdecenter. Plot for the same is attached.

  8673   Tue Jun 4 20:19:07 2013 ranaConfigurationIOOChanged threshold for FSS SLOW loop

The FSS SLOW actuator often runs off away from zero and into a region where the mode hopping is bad and makes a lot of frequency noise (e.g. that 8 hour period a few weeks ago when Jamie couldn't lock the MC).

It should not have this behavior. The SLOW loop should only be running when the MC is locked.

Today I found that the threshold was set back to 0.2 V (which is approximately the correct value for the RefCav locking). Its being compared to the MC TRANS, so the correct value should be ~1/2 of the maximum MC TRANS.

To find this out, I read this piece of text:

    # Make sure the loop is supposed to be active
    if (get_value("C1:IOO-MC_TRANS_SUM") < get_value("C1:PSL-FSS_LOCKEDLEVEL")) {
    print("Reference Cavity not locked -- control loop disabled.\n");
    next;
    }

from scripts/PSL/FSS/FSSSlowServo. I set the threshold using the commmand:

caput -c -t C1:PSL-FSS_LOCKEDLEVEL 12000

Then I restarted the code on op340m, by typing:

> nohup FSSSlowServo

and then closing the terminal. Seems to be behaving correctly now. Previously, the value was so low that the SLOW loop was never turning itself off.

  8718   Tue Jun 18 18:24:07 2013 ManasaUpdateIOOMC WFS turned OFF

[Jenne, Jamie, Manasa]

Jamie was working on the MC guardian today (I think he will elog about this soon).

After this, I received the MC locked in TEM00 with MC_REFL at ~2.5 counts from Jamie. Usually the WFS would do their job in this case to bring MC to a good locking condition and since this did not happen, I figured out that something was wrong with the MC_WFS.

What we did:

1. The WFS were turned off. 

2. As a first step, we wanted to run the WFS_OFFSET script (Koji's elog) which requires MC to be locked with MC_REFL<0.5 and spot positions centered. The autolocker was disabled and MC locked manually to MC_REFL<0.5. 

3. While running the WFS_OFFSETS script, Jamie pointed out that the inputs to the WFS servo had been turned off. After the WFS_OFFSET script finished running we turned ON the WFS inputs. 

4. Following this, the MC was relocked manually and MC spot positions were measured (all spot positions were decentered by < 2 mm). 

5. We ran the WFS_OFFSET script again and turned the WFS back ON. But this would still kick the MC out of lock. 
 

Status: MC is locked with WFS turned OFF. Jamie will be looking through what changes he had made earlier today to fix this problem. 

 

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

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

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

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

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

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

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

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

  1. Modified the on/off scripts so that the Integrators are no longer toggled. No reason to turn them off since we are clearing the filter bank histories.
  2. With QPD feedback OFF, I have lowered the overall gain by 15x so that its just drift control.
  3. Deleted unused / bad filters from the main filter banks.
  4. Gautam is going to debug the QPD with a red laser pointer and then elog.
  5. Jamie is checking out the MC Coil dewhitening logic to see if that's in a funny state.
  8735   Thu Jun 20 20:46:16 2013 gautamUpdateIOOWFS debugging-QPD debugging

 

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

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

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

The interpretation of the figure is as follows:

quadrant 1 on screen QPD=bottom right quadrant on QPD

quadrant 2 on screen QPD=top right quadrant on QPD

quadrant 3 on screen QPD=top leftt quadrant on QPD

quadrant 4 on screen QPD=bottom left quadrant on QPD

MC_WFS_OUT was turned back ON.

 

 

 MC2_QPD-map.png

 

 

  8756   Wed Jun 26 13:37:13 2013 JenneUpdateIOOMC very misaligned - put back

Not sure why it was so poorly aligned, since the misalignment "event" happened while we were all away at lunch, but I steered the MC optics until their SUSYAW and SUSPIT values were about the same as they were before they got misaligned.  MC autolocker took over, and things are back to normal.

  8794   Wed Jul 3 10:39:25 2013 manasaUpdateIOOMC aligned and WFS enabled

I found WFS had been left disabled from sometime yesterday. I don't see anyone mentioning  when and why they had turned OFF the WFS servo.

I aligned MC and turned ON the WFS servo. MC is back.

  8815   Tue Jul 9 20:09:53 2013 KojiUpdateIOOWFS debugging

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

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

The script mcwfsup was also modified accordingly.

  8843   Sun Jul 14 17:47:28 2013 KojiUpdateIOOMC WFS maintenance

Annalisa notified me that the MC autolocker could not keep the MC locked.

I found the initial alignment was not good and the MC was too much excited when the WFS kicked in.

There might have been the WFS offset issue due to the miscentering of the spots on the WFS diodes.

I used the usual procedure of the maintenance and it looked OK if I followed the switching procedure the mc autolocker suppoed to do.
http://nodus.ligo.caltech.edu:8080/40m/7452

I still could not get the autolocker running smoothly. I opened mcup script and compared what was the difference
between my manual sequence and what the script did. The only difference was the lines related to MCL.
It was still turning on the filter module. I checked the MCL path and found that the gain was not zero but 1.0.
So now the MCL gain is set to zero. This solved all the remaining issue.

  8906   Tue Jul 23 13:55:08 2013 KojiUpdateIOOMC manually aligned

The MC was manually aligned. The spot positions were measured and it is consistent with the measurements done yesterday.

  8913   Tue Jul 23 21:32:43 2013 KojiUpdateIOOFound the cause of mysterious MC motion

Thesedays we were continuously annoyed by unELOGGED activities of the interferometer.

MC2 LOCKIN was left on and has continuously injected frequency noise and beam pointing modulation
during all of the comissioning / vent preparation.

C1:SUS-MC2_LOCKIN2_OSC_FREQ was 0.075
C1:SUS-MC2_LOCKIN2_OSC_CLKGAIN was 99

For more than a week ago we noticed that the curve of the MC WFS stripchart suddenly got THICKER.
MC WFS, arm transmission, beam pointing... everything was modulated.
It was not WFS instability, and it was not the cavity mirrors.

Today I made the investigation and finally tracked down the cause of this issue to be on MC2 suspension.
Then it was found that this LOCKIN was ON.

There is no direct record of this lockin in the frame files.
From the recorded channel "C1:IOO-WFS2-YAW_OUT16" (which is the trace on the StripTool chart on the wall)
It was turned on at July 10th, 2:00UTC (July 9th, 7PM PDT)

  8917   Wed Jul 24 14:26:24 2013 ranaUpdateIOOFound the cause of mysterious MC motion

Yes, this was not ELOG'd by me, unfortunately. This was the MC tickler which I described to some people in the control room when I turned it on.

As Koji points out, with the MCL path turned off this injects frequency noise and pointing fluctuations into the MC. With the MCL path back on it would have very small effect. After the pumpdown we can turn it back on and have it disabled after lock is acquired. Unfortunately, our LOCKIN modules don't have a ramp available for the excitation and so this will produce some transients (or perhaps we can ezcastep it for now). Eventually, we will modify this CDS part so that we can ramp the sine wave.

  9030   Mon Aug 19 11:30:20 2013 JenneUpdateIOOMC mirrors' ASC has non-zero inputs

[Masayuki, Jenne]

When I came in this morning, I noticed that the Mode Cleaner had not been locked for at least the past 8 hours.  We moved the MC SUS sliders until the MC SUSPIT and SUSYAW values for each mirror were back to approximately the place they were the last time the MC was nicely locked (~12 hours ago).  This got the MC flashing TEM00, so we thought we were doing well. 

However, if the servo was enabled, any time the cavity flashed a small-order mode (especially 00), the mirrors would get super kicked.  Not good

We went to investigate, and discovered that the RFPD aux laser was left on again.  We turned that off, however that didn't fix the situation. 

Manasa suggested checking that the WFS were really, really off.  When we looked at the WFS master screen, we noticed that although the WFS servos were off, the MC mirrors' ASC filter banks had non-zero inputs.  We checked, and this is not from the MCASS, nor is it from the MC WFS lockins.  At this point, I have no idea where these signals are coming from.  I have turned off the ASC outputs for all the MC mirrors (which means that we cannot turn on the WFS), and the MC locks fine

So, we need to know where the ASC signals are coming from.  There isn't anything that I can see, from any screen that I can find, that indicates some signals being sent over there.  Has anyone done anything lately?  I know Koji was working on IPC stuff the other day, but the MC was locking fine over the weekend until yesterday afternoon, so I suspect that's not the culprit. 

I have turned off the outputs of the WFS lockins, as part of my turning things off, so if whatever script needs them doesn't enable them, they should be turned back on by hand.

  9032   Mon Aug 19 15:23:07 2013 KojiUpdateIOOMC mirrors' ASC has non-zero inputs

[Jenne, Koji]

This disturbance in the MC ASC channels were fixed.

This craziness happened ~10pm last night. Was there any action at the time? >> Sunday-night workers? (RXA: No, Nakano-kun and I left before 9:30 PM)

We found that the signals came from c1ioo. However, restarting, recompiling c1ioo and c1mcs didn't help
to clean up this issue. Just in case we cleaned up the corresponding entries in the ipc file /opt/rtcds/caltech/c1/chans/ipc/C1.ipc
and recomplied c1ioo and c1mcs because these are the channels we touched last week to mitigate the timing out issue of c1rfm.

Incidentally, we fell into a strange mode of the RCG: IOPs could not restart. We ended up running "sudo shutdown -r now"
on each machine (except for c1lsc which was not affected by this issue). This solved the issue.

Even now c1oaf could not be running properly. This is not affecting the IFO operation right now, but we need to look into this issue again
in order to utilize OAF.

  9046   Wed Aug 21 19:26:19 2013 ranaUpdateIOOFound the cause of mysterious MC motion

Quote:

Yes, this was not ELOG'd by me, unfortunately. This was the MC tickler which I described to some people in the control room when I turned it on.

As Koji points out, with the MCL path turned off this injects frequency noise and pointing fluctuations into the MC. With the MCL path back on it would have very small effect. After the pumpdown we can turn it back on and have it disabled after lock is acquired. Unfortunately, our LOCKIN modules don't have a ramp available for the excitation and so this will produce some transients (or perhaps we can ezcastep it for now). Eventually, we will modify this CDS part so that we can ramp the sine wave.

 I've written a new TICKLE script using the newly found 'cavget' and 'cavput' programs. They are in the standard epics distribution as extension binaries. They allow multichannel read/write as well as ramping, delays, incremental steps, etc. http://www.aps.anl.gov/epics/tech-talk/2012/msg01465.php.

Running from the command line, they seem to work fine, but I've left it OFF for now. I'll switch it into the MC autolocker at some point soon.

  9148   Fri Sep 20 20:27:18 2013 ranaUpdateIOOmode cleaner not locking

 I used our procedure from this entry to set the IMC board offset as well as the FSS board offset.

I found this afternoon that the MC was having trouble locking: the PC path was railing as soon as the boost was engaged. Could be that there's some misalignment on the PSL which has led to some RAM having to be canceled by this new offset. Let's see if its stable for awhile.

  9153   Sun Sep 22 22:54:28 2013 ranaUpdateIOOmode cleaner not locking

Having trouble again, starting around 1 hour ago. No one in the VEA. Adjusted the offset -seems to be OK again.

  9175   Mon Sep 30 13:02:51 2013 Masayuki,ManasaUpdateIOOPMC and MC alignment

[Manasa, Masayuki]

The MC lost lock around 8+hrs ago. The transmission from PMC was 0.77 this morning, so we aligned the PSL to the PMC using the two steering mirrors before the PMC. We brought the PMC transmission to 0.841. We also aligned the MC, and the MC transmission reflection now is 0.59.

  9190   Thu Oct 3 01:24:31 2013 Jenne, RanaUpdateIOOPMC

The PMC transmission was around 0.78 all day, rather than the usual 0.83ish.  Rana went out to the PSL table and fixed up the PMC alignment.  This should not need to be done very often, so things to check before touching the alignment are FSS / PMC settings (digital stuff).  Make sure that the PC RMS (on the FSS screen) is low (at least below 2, preferably below 1), and that the FSS Fast monitor is near 5ish (not near 0 or 10).  

This is a capture of PMC REFL's camera after Rana was finished. If it doesn't look this good when you finish then you are not done. Never do PMC alignment without looking at the PMC REFL camera.

PMCR_1064822387.bmp

The attached trend shows 80 days of PMC REFL and TRANS. The bad alignment stuff started on Sep 21-24 time period. You know who you are.

  9205   Sun Oct 6 17:05:49 2013 ranaSummaryIOOMC ASC problems

MC unlocked over the weekend and also got severely mis-aligned. It all started around midnight on Saturday.

At first I thought that this was due to the MCS CPU meter being railed at 60 us, so I deleted a bunch of filters in MC1,2,3 that are unused and left over from Den's quantization noise investigations. This reduced the CPU load somewhat, but didn't make any real improvements. Turning on the ASC filter banks in the MC SUS still mis-aligned the MC.

With the MC WFS and MC ASS turned off, there is still some digital junk coming in and misaligning things. Plot attached.

Similar stuff coming in on ITMX, but not ITMY.

Tried restarting various FEs, but there was no effect. Also tried rebooting c1lsc, c1ioo, & c1sus. Finally did 'shutdown -r now' on all 5 computers on the CDS overview screen and simultaneously (almost) pressed the reset button on the RFM switch above the old c1pem crate. Everything came back OK except for c1oaf (I had to manually button his BURT button) and now the ASC inputs on all the SUS are zero when they should be and MC is well locked and aligned.

Rob and I used to do this trick when he thought that a cosmic ray had corrupted a bit in the RFM network.

  9209   Sun Oct 6 22:52:09 2013 Jenne, RanaUpdateIOOinput beam to PMC aligned again

pmcr.pngafter

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

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

Quote:

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

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

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

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

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

  9238   Mon Oct 14 17:51:40 2013 JenneUpdateIOOinput beam to PMC drifted again

Quote:

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

 The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.

I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.

  9256   Mon Oct 21 13:15:52 2013 KojiUpdateIOOPMC aligned

PMC aligned. Trans 0.78 -> 0.83

  9296   Sat Oct 26 21:46:33 2013 RANAUpdateIOOMode Cleaner Tune-UP

 The MC had been unlocked for the last 4 hours and was crying out to me so I gave it some attention. Its happier now.

From the trend (AtM #1), I saw that the MC2 suspension has moved by ~10 microradians. Since the MC cavity divergence angle is lambda/(pi*w0) ~ 200 microradians, this isn't so much, but enough to cause it to lock on bad modes sometimes. Attackmint too shows that there's not much in monotonic drift over the last 40 nights.

I moved back MC2 to its old alignment with these commands:

ezcaservo -r C1:SUS-MC2_SUSPIT_INMON -s -1017 -g 0.0009 C1:SUS-MC2_PIT_COMM -t 300

ezcaservo -r C1:SUS-MC2_SUSYAW_INMON -s 490 -g 0.0009 C1:SUS-MC2_YAW_COMM -t 332

Then I went out to the table and aligned the beam into MC using the last two steering mirrors good enough so that the WFS coming on doesn't make the visibility any better. In this nominal state, I unlocked the MC and then aligned the reflected beam onto the center of the LSC PD as well as the WFS. The beam on the first WFS is a little small - next time someone wants to improve our Gouy phase telescope, we might try to make it bigger there. On the LSC PD, the beam was off-center by a few hundred microns.

  9303   Mon Oct 28 14:12:48 2013 manasaUpdateIOOMode Cleaner relocked

Quote:

 The MC had been unlocked for the last 4 hours and was crying out to me so I gave it some attention. Its happier now.

From the trend (AtM #1), I saw that the MC2 suspension has moved by ~10 microradians. Since the MC cavity divergence angle is lambda/(pi*w0) ~ 200 microradians, this isn't so much, but enough to cause it to lock on bad modes sometimes. Attackmint too shows that there's not much in monotonic drift over the last 40 nights.

I moved back MC2 to its old alignment with these commands:

ezcaservo -r C1:SUS-MC2_SUSPIT_INMON -s -1017 -g 0.0009 C1:SUS-MC2_PIT_COMM -t 300

ezcaservo -r C1:SUS-MC2_SUSYAW_INMON -s 490 -g 0.0009 C1:SUS-MC2_YAW_COMM -t 332

Then I went out to the table and aligned the beam into MC using the last two steering mirrors good enough so that the WFS coming on doesn't make the visibility any better. In this nominal state, I unlocked the MC and then aligned the reflected beam onto the center of the LSC PD as well as the WFS. The beam on the first WFS is a little small - next time someone wants to improve our Gouy phase telescope, we might try to make it bigger there. On the LSC PD, the beam was off-center by a few hundred microns.

Masayuki was running LAN cables near the MC2 chamber. This caused the MC2 suspension to move and unlocked the MC. I looked at the long term (2 days) and short term (2 hours) trend of the MC suspensions. I restored the old alignment as described above using ezcaservo.

C1:SUS-MC2_SUSPIT_INMON was restored to 1020 and C1:SUS-MC2_SUSYAW_INMON was restored to 490.

Attachment: Dataviewer trend (2 hours)

  9306   Mon Oct 28 21:33:55 2013 RANAUpdateIOOMode Cleaner Tune-UP

 

8 day minute trend of some of the IMC alignment signals.

That step ~2 days ago in the WFS2 yaw control signal shows that I didn't do such a good job on yaw.

Nic is going to come over some time and give us a new Gouy telescope that let's us have bigger beams on the WFS. At LLO, Hartmut demonstrated recently how bigger beams can reduce offsets somehow...mechanism TBD.

Also, we must angle the WFS and figure out how to dump the reflections at the same time that we rework the table for the telescope.

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 

  9315   Wed Oct 30 01:53:52 2013 JenneUpdateIOOMode Cleaner relocked

The MC (mostly MC2) decided a few minutes ago to move, so I put the SUSPIT and SUSYAW numbers back where they were, and the tweaked up the alignment from there to get a low MC REFL DC number.  Now the MC is staying locked again, after 20 minutes of not.

  9320   Wed Oct 30 16:46:17 2013 manasaUpdateIOOMC aligned

MC has not been very happy since last night. 

What I did to fix this:

1. Disabled autolocker and WFS and aligned the MC to bring MC REFL down to <0.50

2. When I re-enabled autolocker, MC was losing lock everytime WFS turned ON.

3. I relocked MC, measured the spot positions and moved MC spot positions by running /opt/rtcds/caltech/c1/scripts/ASS/MC/mcassMCdecenter 
and 
/opt/rtcds/caltech/c1/scripts/MC/moveMC2/

4. I reset the WFS offsets by running /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets

5. MC is locked and looks happy right now with REFL DCMON at ~0.5

 

  9322   Thu Oct 31 15:34:28 2013 manasaUpdateIOOMC not happy since yesterday

Quote:

 

8 day minute trend of some of the IMC alignment signals.

That step ~2 days ago in the WFS2 yaw control signal shows that I didn't do such a good job on yaw.

Nic is going to come over some time and give us a new Gouy telescope that let's us have bigger beams on the WFS. At LLO, Hartmut demonstrated recently how bigger beams can reduce offsets somehow...mechanism TBD.

Also, we must angle the WFS and figure out how to dump the reflections at the same time that we rework the table for the telescope.

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 

The MC has not been able to hold lock for over a couple of hours since yesterday. I aligned the MC yesterday (elog 9320) and it lost lock in a couple of hours. I realigned the MC again around noon today only to see it drifting and lose lock again.

I have attached the MC trend for the 2 hours when the MC drifted slowly from its happy to sad state.

 

 

  9323   Thu Oct 31 20:05:48 2013 RANAUpdateIOOMode Cleaner Tune-UP

Quote:

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 I couldn't find any dumps near the WFS. Koji looked. I looked twice. Maybe they are spooky and absorbing all of the light?

The MC alignment was bad and the WFS were making it drift. Koji aligned the beam into the PMC. I then restored the MC suspensions to where they were 8 days ago (back when the transmission and reflection were good). With the WFS OFF, this gave us a MC trans ~ 16000. With WFS ON it goes to 17500 which is about as good as its been over the last 80 days.

I centered the beam on the WFS with the MC unlocked and also centered the beam on the whole WFS path (it was near clipping between WFS 1 & 2). Also for some reason that beamsplitter which steers the beam onto WFS1 is a R=33% (!? why is this not a R=50% ??).

Steve, please swap this out to a BS1-1064-50-1025-45S if we have one sitting around. If not, we want to add this to the CVI purchase list, but not buy until we get a bigger list together.

I also centered this newly aligned beam into the IMC onto the PSL QPDs. We should now use these as a pointing reference for the beam into the IMC.

While doing this I noticed that the beam was almost clipping on the Uniblitz shutter used to block the PSL beam. That shutter is mounted too short and was also not centered horizontally. I removed it for now so that Steve can find a more adjustable mount for it and put it back into play. The beam going into the IMC is BIG, so you have to very careful when centering the shutter. Might be that we cannot leave it at 45 deg and still get a big enough aperture.

Note #3 for Steve: please also replace the mount for last steering mirror into the IMC with a Polanski or a Superman, that black Ultima is no good. Also the dogs must be steel - no aluminum dogs for our sensitive places.

  9324   Thu Oct 31 21:22:00 2013 rana, kojiSummaryIOOmodulation beat note in MC servo

I hooked up the 4395 to the MC servo board test out (TP2A) and looked at the spectrum using our new SPAG4395.py script. We noticed a huge peak at ~3.8 MHz and correctly guessed that it was due to the beat between the MC modulation frequency 29.5 MHz and 3*f1 (~33 MHz).

So we tuned the Marconi for the main mod. from 11065910 to 11066099 Hz and saw the beat note disappear (to within the 1 Hz tuning precision of our Marconi).

New MC length tuning method! Alert the LA Times!

13031.png13031_200.png13031_200b.png

My conjecture is that this temperature dependent mismatch between the modulation frequency (f1) and the MC length  is what leads sometimes to our nasty saturating PC DRIVE signal. TBD.

  9325   Fri Nov 1 09:45:32 2013 SteveUpdateIOObeam dumps to be find

Quote:

Quote:

Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??    

            Tuesday: Razor dumps are waiting for you.

 I couldn't find any dumps near the WFS. Koji looked. I looked twice. Maybe they are spooky and absorbing all of the light?

The MC alignment was bad and the WFS were making it drift. Koji aligned the beam into the PMC. I then restored the MC suspensions to where they were 8 days ago (back when the transmission and reflection were good). With the WFS OFF, this gave us a MC trans ~ 16000. With WFS ON it goes to 17500 which is about as good as its been over the last 80 days.

I centered the beam on the WFS with the MC unlocked and also centered the beam on the whole WFS path (it was near clipping between WFS 1 & 2). Also for some reason that beamsplitter which steers the beam onto WFS1 is a R=33% (!? why is this not a R=50% ??).

Steve, please swap this out to a BS1-1064-50-1025-45S if we have one sitting around. If not, we want to add this to the CVI purchase list, but not buy until we get a bigger list together.

I also centered this newly aligned beam into the IMC onto the PSL QPDs. We should now use these as a pointing reference for the beam into the IMC.

While doing this I noticed that the beam was almost clipping on the Uniblitz shutter used to block the PSL beam. That shutter is mounted too short and was also not centered horizontally. I removed it for now so that Steve can find a more adjustable mount for it and put it back into play. The beam going into the IMC is BIG, so you have to very careful when centering the shutter. Might be that we cannot leave it at 45 deg and still get a big enough aperture.

Note #3 for Steve: please also replace the mount for last steering mirror into the IMC with a Polanski or a Superman, that black Ultima is no good. Also the dogs must be steel - no aluminum dogs for our sensitive places.

No wonder they could not find the beam dumps. Last night was Haloween. They should of just said: Trick or treat! where are the beam dumps?

ELOG V3.1.3-