I modified autolocker for MC in low power mode (/opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m_low_power) to make it work with the current directory structure.
autolockMCmain40m_low_power currently runs on op340m and it is in crontab.

34 * * * *  /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m_low_power >/cvs/cds/caltech/logs/scripts/mclock.cronlog 2>&1


MC intra-cavity power:
  Currently, incident beam to the MC measured at PSL table is ~15 mW. Reflected power from MC (C1:IOO-MC_RFPD_DCMON) is 0.94 when MC unlocked, and is 0.088 when locked.
  That means, considering MC1/3 power transmission is 2000ppm (calculated finnesse=1570), intra-cavity power in MC is ~7 W.

  15 mW * (0.94-0.088)/0.94 / 2000ppm = 7 W

  We can increase the power by factor of ~2, if needed.


MC beam spot positions:
  I aligned MC to maximize transmission (C1:IOO-MC_TRANS_SUM_ERR), and measured the MC beam spot posisions in atm, low power.

# filename    MC1pit    MC2pit    MC3pit    MC1yaw    MC2yaw    MC3yaw    (spot positions in mm)
./dataMCdecenter/MCdecenter201206290135.dat    2.914584    4.240889    2.149244    -7.117336    -1.494540    4.955329    before vent
./dataMCdecenter/MCdecenter201207011253.dat    3.294659    3.416584    2.620511    -6.691800    -3.164084    4.806517    after vent

  They look the same within the error of the measurement, except for the spot positions on MC2, which we don't care.


Autolocker should be refined:
  To make autolockMCmain40m_low_power, I copied autolockMCmain40m and just changed

- lockthresh from 500 to 100
- use mcdown_low_power instead of mcdown
- use mcup_low_power instead of mcup

  The difference between mcdown_low_power and mcdown should be only

- ezcawrite C1:IOO-MC_REFL_GAIN 31 for lowpower, 9 for usual
- ezcawrite C1:IOO-MC_VCO_GAIN 10 for lowpower, -5 for usual

  The difference between mcup_low_power and mcup should be only

- ezcawrite C1:IOO-MC_REFL_GAIN 31 for lowpower, 12 for usual
- ezcawrite C1:IOO-MC_VCO_GAIN 31 for lowpower, 25 for usual

  Currently, they are not like that. Somebody good at shell scripts should combine them and make it into one code with an option something like usual/low-power.

MC came back to the state as it was before the vent.

What I did:
  1. Removed beam attenuating setup on PSL table(see elog #6892).

  2. Removed 100% reflection mirror before the MC reflection PD and put 10% BS back, so that we can have MC WFS. Also, I changed C1:IOO-MC_RFPD_DCMON.HOPR to 5.

  3. Removed autolockMCmain40m_low_power from crontab on op340m, and put autolockMCmain40m again.

  4. Aligned MC and ran /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets to adjust WFS offsets.

  5. Measured beam spot positions. They looked same as before the vent.

# filename    MC1pit    MC2pit    MC3pit    MC1yaw    MC2yaw    MC3yaw    (spot positions in mm)
./dataMCdecenter/MCdecenter201206290135.dat    2.914584    4.240889    2.149244    -7.117336    -1.494540    4.955329    before vent
./dataMCdecenter/MCdecenter201207011253.dat    3.294659    3.416584    2.620511    -6.691800    -3.164084    4.806517    after vent
./dataMCdecenter/MCdecenter201207032009.dat    3.737099    3.994597    3.087857    -6.442053    -0.992543    4.714607    after pumping (now)

  6. I also turned on high voltage power supplies for input and output PZTs

  7. Below is captured Sensoray images of the current state.



Next:
  I will go on to check if IFO works as it was before or not, but I think we should center MC beam spot positions and see if we can avoid clipping in the near future.

Last night I worked on the MC incident beam such that we can hit the center of the MC mirrors.

Steve and I checked the incident beam on MC1. We found the beam is ~5mm south.
This was not too critical but it is better to be realigned. I moved the steering mirror on the OMC
table (in vac). We kept the MC resonated. After the maximization of the resonance, I realigned the
MC1 and MC3 such that the resonance in dominated by TEM00.

Jenne, Kiwamu, and I then closed the light door on to the OMC/IMC.

I will make more detailed entry with photos in order to explain what and how I did.

As per Steve's request I checked the MC incident power as a function of time.

The output is negative: the lower voltage, the higher power.

Before I put the attenuator the incident power was 1.1W. It appear as -5V.

Now the output is -0.1V. This corresponds to 22mW.

The MC suspensions were not damping and the reason was traced to the empty imput matrices in the suspension controls.  This has been an issue in the past as well when the sus machine is rebooted some of the burt restore does not populate these matrices.

I ran the burtgooey and restored c1mcs.snap file.  from a couple of hours ago.

[Suresh / Kiwamu]

 The attenuator was removed and now the MC is happily locked with the full power of 1.2 W.

(what we did)

 + replaced the perfect reflector, which was before the MCREFL_PD, by a 10% beam splitter like it used to be.

 + removed the attenuator (combination of HWP and PBS).

 + realigned the beam path on the AP table, including the MCREFL path and WFS path.

 + made the aperture of the MC2F camera narrower in order to avoid a saturation.

 + aligned the MC suspensions so that it resonates with the TEM00 mode.

 + put a ND filter on the AS camera

(notes)

C1:IOO-MC_RFPD_DCMON = 0.98 (locked)

C1:IOO-MC_TRANS_SUM = 17500 (locekd)

(next things to do)

 + measurement of the spot positions on each MC mirror.

 + centering of the beam spot by steering the input mirrors on the PSL table

[Koji / Kiwamu]

 The MC is now back to normal. The beam pointing to the interferometer is good.

There were two different issues :

• A mechanical mount was in the MC WFS path.
• There were some loose connections in the SUS rack

Slid have we the position of the mechanical mount. Nicely the WFS beam go through now.

And also I pushed all the connectors associated with the MC SUS OSEMs in the SUS rack.

After pushing the connectors, the MC1 OSEM readouts dramatically changed, which actually more confused us.

As shown in the 3 hours trend below, the OSEM readouts have changed a lot (shown in the middle of the plot with arrows). Some bumps after the steps correspond to our alignment efforts.

I measured the power transmitted from the PSL to the MC. It is 19mW.

The MC is now locked.  The MC Autolocker script cannot be used now since the tigger conditions are not met.  It has been disabled on the C1IOO-LOCK_MC screen.  The boost switch also is set to zero.  Increasing the boost results in MC unlocking. 

The C1:IOO-MC_RFPC_DCMON was going from 1.4 (MC Unlocked) to 0.66 (MC_locked).  I thought we ought to have a factor of ten drop in this since under high power conditions we used to have a drop of about 5.6 to 0.6.   So I adjusted the zig-zag at the end of the PSL table to improve the alignment.  It now goes from 1.4 to 0.13 when the MC is locked.   The lock is also much more stable now.  It still does not tolerate any boost though.

I checked to make sure that the beam centering on MC_REFL PD is optimal since I touched the zig-zag.  The RFPD output is now 0.7V (MC unlocked).  This matches well with the fact that we used to have 3.5V on it with the MC unlocked.  And we have cut the down the power incident on this by a factor of 5.  Because 1W -> 20mW at the PSL table  and 10% BS -> 100% Y1-...

I just turned off the PSL enclousure lights.
 

[Suresh / Koji]

The MC mirrors are aligned. Now the flashing of the resonances are visible on the MC2 CCD

although the modematching seemed pretty poor.

- The incident power was adjusted to be ~20mW by rotating HWP after the laser source.
The power before the window of the chamber was ~450mW. Where are those missing 1.5W?

- We checked the spot on the last two steering mirrors and the incident beam on MC1.
The beam was too much off from the center of the 1st steering mirror. It was also hitting 1cm north of the MC1.
We adjusted the steering mirrors such that the incident and reflected beams are symmetrically visible at the MC1 tower.

- The MC mirrors are aligned. We first tried to use only MC2 and MC3. And then we used MC1 too as the spot on the MC2 was too high.

- We saw some TEM00 flashes but with many other modes flashing. We checked the beam diameter on the PSL table and on the MC REFL.
The latter one looked twice large as the former one. We concluded the beam is diverging.

- We closed the tank and decided to work on the mode matching tomorrow.

[Nancy and Koji]

We restored the full power operation of the MC.

Restoration of the suspensions

1. Found the suspension watch dogs are left turned off.
2. Found c1susvme1/2 were not running.
3. Launched the realtime processes on c1susvme1/2 and c1iscey
4. Restored the watch dogs. The suspensions looked fine.

Preparations for the high power

1. Put an ND2.0 before the MCT CCD. Confirmed the ND reflection is damped.
   MCT QPD is not necessary to be touched.

The high power operation of the MC / post lock adjustment

1. Locked the MC under the autolocker being disabled.
2. Adjusted the aperture on the MC2 face camera
3. Adjusted the spot positions on the WFS QPDs
4. Reverted the scripts to the high power ones
   (mcup / mcdown / autolockMCmain40m)
5. Logged in to op340m and restarted autolockMCmain40m

The autolocker seems working correctly.

Jenne asked us to keep th MC locked and let the seismometers happy through this weekend.
Note that the work at the control room and the desks are no problem as far as you are quiet.

Nancy told Jenne and me that she finished the work and reverted the WFS to the old state at 4:30AM.
She could not make the elog as it has been crashed.

MC and old MC WFS looks working as usual.

From 6:40AM to 9:40AM the oscillation of the PMC looks present.

At 10:30AM I reduced the gain of the PMC from +15dB to +13dB.

SR620                Marconi
                     199178070
165981524            165981725
                     132785380
                      33196345

Pete, Rob, Alberto,

yesterday we thought that some of the problems we were having in locking the IFO might be related to a change of the length of the mode cleaner. So today we decided to measure it again.

We followed the Sigg-Frolov technique (see 40m Wiki, Waldman, Fricke). For the record, the MC_AO input corresponds to IN2 on the MC Servo board.

We obtained: L = 27.092 +/- 0.001 m

From the new measurement we reset the frequencies of the Marconis to the following values:

33196450 Hz

132785800 Hz

165982250 Hz

199178700 Hz

New              OLD
--------------------------
165983145        165977195

New              OLD
--------------------------
27.0924          27.0934    [m]

New              OLD
--------------------------
165983145        165977195

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

• Made the C1:IOO-WFS_TRIG_WAIT_TIME (delay in WFS trigger) from 3s to 0s.
• Reduced C1:IOO-WFS_TRIGGER_THRESH_ON (Switchin on threshold) from 5000 to 1000.
• Then as soon as a TEM00 was locked with poor efficiency, the WFS loops started aligning the optics to bring it back to lock.
• After robust lock has been acquired, I restored the two settings I changed above.

[Koji, Anchal]

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

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

The MC was sort of misaligned. It was locking on some vertical HOMs. So I locked it and aligned the suspensions to the input beam (not great; we should really align the input beam to the centered spots on the MC mirrors).

With the HOMs reduced I looked at the MC servo board gains which Guatam has been fiddling with. It seems that since the Mod Depth change we're getting a lot more HOM locks. You can recognize this by seeing the longish stretches on the strip tool where FSS-FAST is going rail-to-rail at 0.03 Hz for many minutes. This is where the MC is locked on a HOM, but the autolocker still thinks its unlocked and so is driving the MC2 position at 0.03 Hz to find the TEM00 mode.

I lowered the input gain and the VCO gain in the mcdown script and now it very rarely locks on a HOM. The UGF in this state is ~3-4 kHz (I estimate), so its just enough to lock, but no more. I tested it by intentionally unlocking ~15 times. It seems robust. It still ramps up to a UGF of ~150 kHz as always. 'mcdown' commited to SVN.

[Kiwamu Suresh Koji]

Some main parameters of the PSL has been recovered using Dataviewer and some screen snapshots, as seen in the screenshots below.

[MC Board]
C1:IOO-MC_REFL_GAIN 14
C1:IOO-MC_REFL_OFFSET -4.2381
C1:IOO-MC_BOOST1 0   (You can turn it on if you want, but turn it off for locking)
C1:IOO-MC_BOOST2 0
C1:IOO-MC_POL 1   (Minus)
C1:IOO-MC_VCO_GAIN 4
C1:IOO-MC_LIMITER 1 (Disable)

[FSS box]
C1:PSL-FSS_SW1 0 (Test1 ON)
C1:PSL-FSS_INOFFSET 0.1467
C1:PSL-FSS_MGAIN 30
C1:PSL-FSS_FASTGAIN 14 (Do not increase it, at least while locking. Otherwise the phase lag from the PZT loop gets significant and the MC loop will be conditionally stable).

I locked to PSL loops, then tweaked the alignment of the MC to get it to lock. 

I first steering MC1 until all the McWFS quads were saturated.  This got the MC locking in a 01 mode.  So I steered MC1 a little more till it was 00.  Then I steered MC2 to increase the power a little bit.  After that, I just enabled the MC autolocker.

[Mirko, Den]

While the MC was unlocked (and the local damping off) we've measured the coherence between GUR1_X and OSEM sensors. It was rather high, close to 1 at frequencies 0.1 - 1 Hz. That means that stack does not kill all coherence between seismic noise and mirror motion.

Then we've turned on the local damping and measured the coherence again between GUR1_X and OSEM sensors. It decreased due to some noise and was on the level of ~0.5. We did reduced the motion between the mirror and the frame by local damping but it is not obvious that we lost some coherence due to this effect. Probably, actuator adds some noise.

When we locked the MC, we did not see any coherence at 0.1 - 1 Hz between GUR1_X or STS1_X and OSEM sensors of MC1 and MC3 but we did see with MC2. The MC1 sensor was fixed by Suresh.

[Yuta, Manasa, Sendhil, Rana]

With MC REFL PD fixed, we aligned MC in high power enabling a fully functional MC autolocker.
We then unlocked MC and aligned the PD and WFS QPDs. Also we checked the MC demodulator and found a ~20% leakage between the Q-phase and I-phase. This must be fixed later by changing the cable length.

We adjusted MC offsets using /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets.
We then measured the MC spot positions using  /opt/rtcds/caltech/c1/scripts/ASS/MC/mcassMCdecenter
Spot positions seem to have shifted by 2mm in yaw.

We will proceed with aligning the arms now.

I found the MC2 face camera disabled(?) and the MC servo board input turned off. I turned the MC locking back on but I don't see any camera image yet.

The MC2 has 2 GigE cameras right now. I'll put back the analog asap.

(Rana, Koji, Suresh, Yuta, Thanh, Kiwamu)

 MC was locked successfully !

 Instead of feeding back the signal to the MC length we just injected it to the NPRO pzt with a high voltage (HV) amplifier.

So now we can move on to an in-vac work which needs the main beam to align the stuff.

(mode matching to MC)

Suresh and Thanh (a visitor from ANU) improved the mode matching to the MC. 

As written in the entry #3779  the beam after the mode matching lenses were diverging.

It is supposed to converge from 1.7mm radius at the last lens to 1.6 mm radius at the middle point of MC1 and MC2.

They slided the last lens toward the MC to make it more collimated and roughly measured the beam size using a sensor card.

As a fine tuning, they looked at some higher order modes showing up in the MC2 camera, and tried reducing the higher order modes by slightly sliding the last lens.

(assuming the lens position doesn't so much change the alignment)

During the work we removed a steering mirror for green locking because it was on the way of the lens slider.

- - measured optics' distances - - 

25.5 cm  from 1st lens to the front surface of the EOM

5.5 cm  length of the EOM

24.5 cm from the front surface of the EOM to the 2nd lens (concave)

15.5 cm  from the 2nd lens to the 1st steering mirror in the zig-zag path

20.5 cm  from the steering mirror to the last lens

(preparation for locking) 

Rana, Yuta and Koji prepared an old instant amplifier which can produce +/-13V output instead of usual SR560s.

We added an offset (~5V) on the signal to make it within 0-10V which is the input range of the HV amplifier.

If we take SR560, it's probably not sufficiently wide range because they can handle handle only about +/-4V.

We strung a cable from Marconi via the RF stabilizer to the wideband EOM in order to drive the EOM at 24.5MHz.

SInce the EOM doesn't have 50 Ohm input impedance we had to put a 50 Ohm load just before the EOM in order to drive it efficiently.

From a medm screen we set the driving RF amplitude slider (C1:IOO_MCRF_AMPADJ) to 0.0, which provides the maximum RF power on it.

(locking mode cleaner)

At first we unlocked the PMC to see an offset in the error signal without any lights on the MC_REFL PD.

Then we adjusted the offset to zero on the MC servo screen.

At the beginning of the locking the PMC was not stable for some reasons during the MC was locked.

But after increasing the laser power to the MC twice bigger, it looks like the PMC and the MC are quite stable.

[Jenne, Raji]

We replaced the MC Refl path BS with the Y1, as usual, so that the full ~100mW goes to the REFL PD, so we don't have WFS or MC refl camera. 

The MC spots were all outside of 1mm, and some were beyond 2mm (for MC1,3, P,Y....MC2 is of course free since we have more DoFs than we need), so we touched (very, very slightly) the zigzag mirrors on the PSL table.  We realigned the MC, and now the spots are centered to my satisfaction.

MC1,2,3 Pit,    MC1,2,3 Yaw (in mm):

[0.46444020918749457, 8.2634316545130009, -0.41417975237831089, -0.89401481457980592, -0.9323196976382162, -1.543145765853893]

MC2 is way off in pitch, according to this measurement, and it's been consistently going down as we move the MC2 spot in the same direction (up on the monitor), but since we started at +15mm and are now at +8, and we've gone quite a ways, I'm not sure that we really want to go all the way to 0.  Anyhow, MC1 and MC3 are the ones which define our input pointing, so we're quitting for tonight.

We will turn on the PZTs and begin with the official vent list for dummies tomorrow.

[Rana, Ayaka, Jenne]

We aligned the REFL beam to the center of PD.
Also we removed the small black parts from mirror holder so that the beam is not clipped. They are originally for holding the mirror, but the mirror should be held by the small screw on the side of the mirror mount. This screw was hidden by the label, so we moved the label on the right hand side of the mirror mount (See a picture below).  

Also we removed the half-wave plates and PBS so that laser power is increased.

Then I aligned the beam for PMC, locked MC, and centered the beam spots.

The MC2 pitch is a little bit high but still close enough to the center.

Jenne had also centered the beam spots on QPDs for WFS.

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&

 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???

The MC seemed to be losing lock recently quite a bit. I noticed that the PC Drive RMS signal was red.

This means that the high frequency drive to the Pockels cell was too high by a factor of 2-3 and sometimes saturating and breaking the lock.

I fiddled with the gains on the FSS screen until this value went down. It looks like there is some kind of high Q oscillation; it takes a couple minutes for the PC Drive RMS to settle to its new position after changing the gains.

The attached trend plot show the last 2 hours. The mean is now back to ~1 V and seems OK. We should really examine the FSS or MC error point spectra with the RF analyzer while exploring this gain space.

The mode cleaner seems to be locking again.  I've manually unlocked it a few times in the past 20min, and most of the time it catches lock again (maybe about 80% of the time).  Other times, it starts to lock in a bad mode, and can't fix itself, so I unlock it, and let it restart and it usually does fine the second time around. 

I'd like it to be a little more robust, but I'm having a bit of trouble zeroing in on the optimal alignment for quickest, most durable lock aquisition of the MC.  Right now I'm going to leave it for a little while to make sure it doesn't fall apart.

 * PMC + MC were unlocked when I came in.

* I fiddled around some more with the mcup/down scripts to make locking snappier. The locking was breaking the PMC lock often, so I re-enabled the MC servo board output limiter during acquisition. It is disabled in the MC UP script.

* Re-measured the MC OLG. Still OK.

* Measured the PZT / EOM crossover (aka the FAST / PC crossover) using the connectors on Koji's summing box. With the FAST gain at 18 dB, the crossover is ~10 kHz. Looks way to shallow. Plots to follow.

* I finally discovered today that the PMC PZT stroke is what's causing the main mis-alignment of the beam going to the IMC. By relocking at a few positions, I could see that the IOO QPDs have steps when the PMC relocks. So the IO beam wander is NOT due to temperature effects on the optics mounts of the PSL table. I wonder if we have a large amount of length to angle coupling or if this is the same as the OMC PZTs ?

P.S. I found that someone is using a temporary bench power supply to power the summing box between the TTFSS and the Thorlabs HV driver...whoever did this has ~48 hours to hook up the power in the right way or else Koji is going to find out and lose it and then you have to wear the Mickey Mouse hat.

http://www.arroyoinstruments.com/files/Arroyo-UsingBenchPowerSupplies_11Apr.pdf

The first attachment shows the OLG measurements with 2 different values of the fast gain (our nominal FG is 18 dB). You can see that the higher gains produce some crossover instability; when tuning the gain we notice this as an increase in the PCDRIVE rms channel.

The second attachment shows the measurement of the 'crossover'. Its really just the direct measurement of the IN1 / IN2 from the FAST summing box, so its the crossover measurement where the OLG is high.

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

[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.

[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.

This morning Steve and I opened the doors on the IOO and OMC chamber to let the IR beam go to MC.

And found the MC flashing is way far from TEM00, there were very higher order modes.

The MC suspensions were realigned based on an assumption that the incident beam didn't change recently.

Anyways we should check the leveling of the IOO table and the spot positions on the MC mirrors again to make sure.

In the last couple days, as the IMC ringdowns have been going on, we have noticed that the MC is behaving bad. Misaligning, drifting, etc.

Gautam told me a horror story about him, Koji, and melted wires inside the sat boxes.

I said, "Its getting too hot in there. So let's take the lids off!"

So then we:

1. Removed the lid (only 4 screws were still there)
2. cut off some of the shield - ground wires and insulated them with electrical tape
3. squished the IDC connectors on tightly
4. left it this way to see if MC would get better - certainly the painfully hot heatinks inside the box were now just 110 F or so

After some minutes, we saw no drifting. So maybe my theory of "hot heatsink partially shorting a coil current to GND through partially melted ribbon cable" makes sense? IF this seems better after a month, lets de-lid all the optics.

Let's look at some longer trends and be very careful next to MC2 for the next 3 days! I have put a dangerous mousetrap there to catch anyone who walks near the vacuum chamber.

gautam: the grounding situation per my assessment is that the shield of all the IDC cables are connected to a common metal strip at 1X5 - but in my survey, I didn't see any grounding of this strip to a common ground.

As per Kiwamu's request I made a light touch to the input steering and the mode matching lens.

Here V_ref and V_trans are C1:IOO-MC_RFPD_DCMON and C1:IOO-MC_TRANS_SUM, respectively.

Result: Visibility = 1 - V_ref(resonant) / V_ref(anti_reso) = 1 - 0.74 / 5.05 = 85%

What has been done:

• Alignment of the steering mirrors before and after the last mode matching lens
     V_ref: 2.7 ==> 2.2, V_trans: 34000 ==> 39000
• Moving of the last mode matching lens away from the MC (+ alignment of the steering mirrors)
     V_ref: 2.2 ==> 0.74, V_trans: 39000 ==> 55000

The MC has been funny since yesterday. I checked the suspensions INMON channels and they seemed ok. So I went ahead and tweaked the alignment with WFS disabled (yesterday). Although the WFS PDs were cenetered at this point, the WFS servo was throwing the MC in a not-so-happy state. We worked with the WFS servo OFF all of yesterday.

This morning,

* I fine tuned the MC alignment from yesterday (TRANS_SUM > 17800 counts)

* measured the spot positions

* recentered the spots on the WFS PDs (was already quite centered)

*reset the WFS filterbank offsets.

The MC has been locked happily since then with autolocker and WFS servo enabled.

Another go at the noise projection from MC1-3 pit/yaw to MC length. This time injecting into the MC autoalignment FB (e.g. C1:IOO-WFS1_PIT_EXC ).

LTPDA is working now, but still the NDS server is not so cooperative.

Summary: Alignment fluctuations of the MC mirrors don't significantly contribute to MC length changes up to at least 3.5Hz. Especially they can't explain the lack of coherence between seismometers and MC length below 1Hz that we worry about for the OAF.

At high frequencies >= 10Hz you can see angle to length coupling as is evident in Sureshes spot position measurements.

Whiteish noise injection:

Injection from 0.1-20Hz.Filtered by the servo filters and zp:[1],[1] , Gain = 1 @ 2Hz

Look at the coherence plots for the quality of the measurement:

Injection details:

DOF      Amplitude[counts]        UTC Time (duration always 4mins)
WFS1p  70                               22:28
WFS1y  55                               22:03
WFS2p  70                               22:13
WFS2y  70                               22:18
None      -                                 22:23

Fixed sine injections:

To get some better SNR at low frequencies I did a fixed sine noise injection at 0.3Hz. See attached files.

DOF      Amplitude[counts]        UTC Time (duration always 4mins)    Lower limit of SNR MC length via mirror misalignment
WFS1p  4                                  00:05                                                29.3
WFS1y  4                                  00:14                                                22.0
WFS2p  4                                  00:19                                                18.5
WFS2y  4                                  00:25                                                18.0

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.

This morning I found the Mode Cleaner unlocked.

I check the sliders for the mirrors bias and they have not changed. Also the OSEMs readbacks show no change in the optics positions.

I don't understand what's wrong because in the previous days, in this state of alignmanet, it could lock.

I tried to tweak a little bit the periscope to check whether it was a problem of beam matching but that didn't help the cavity to lock.

I don't want to change the periscpe alignment to much becasue I believe it is still good and I suspect that there is something else going on.