Kiwamu, Stefan

Tonight we copied the BS OPLEV filters to the BS M2 LOCK pitch and yaw filters, and modified them slightly to get some moderate DC gain on top of a significant suppression at the optics resonances.
 - The modification we made is
   PIT and YAW: FM1: zpk([0],[100],1,"n") was replaced with zpk([0.1;0.1],[4000;100],0.2,"n") . Together with the WFS filter bank (a simple 1/f integrator) this results in very weak DC feed-back.
   PIT: We added a 1.2Hz resonance peak compensation and a p0.1:z1.5 low frequency boost to FM10:
      zpk([0.02+i*1.2;0.02-i*1.2],[0.200028+i*1.18338;0.200028-i*1.18338],1,"n")* zpk([1.5],[0.1],15,"n")
   The results in a reasonable secondary UGF crossing.

Pitch was tested, and resulted in a unconditionally stable loop.
Yaw wasn't tested yet. A snapshot of the engaged filters is attached.

Betsy, Travis, Rick

How today went:

We spent a few hours this morning working on the in-vac side of the new ESD connector termination checkouts. 

At ~2pm we pulled the FC sheet off of the ETMy-HR (painted on last night).  We immediately saw that the 3 larger FC remnants that were causing all of the glint in the cavity arm were removed.  Yay!  However, it was also immediately clear (with the green flashlight) that the 3" ring feature and mottled haze were still there. 

We took a break at 3pm and spoke to a wider SYS+ audience where it was determined we would attempt to do a test drag wipe on the mottling nearer the edge of the optic.  We worked on getting pictures of numerous mottled areas in the haze of the donut shape on the ETMy-HR before doing some test drag wipes.  Then we chose an area toward the top of the optic where there was another relic IAS window circle print near the 12 o'clock position to test drag wiping.  After numerous failed attempts at performing the light-duty friction-only drag wiping technique on this area I resorted to folding the lens wipe a few times and applying pressure during the drag wipe.  This made a smudge where I wiped which I then had to spend another ~5 wipes removing.  We then reevaluated the mottling and found that we might have improved it in one small place, but not the entire area I had been working on.  We then redirected a streaky area at the bottom of the optic to see if I could get a better technique down.  No such luck and I again had to resort to applying pressure numerous times in order to see an improvement.  Since we had better pictures of the 12 o'clock position mottling area that I had been working on earlier, we decided to revisit that area.  I again made an attempt at friction-only drag wiping of this top area.  In the process I must have lightly swiped the optic with my glove because when inspecting the optic after the drag wipe, we found a ~2mmx2mm patch of particulate just outside of the 3" ring near the center of the optic.  Brilliant.  We also found more particulate on the optic from the waving lens tissues.  We tried to blow them off with a few minutes of N2.  This did not seem to work.  One of the particles was quite large and even a light dab with an swab did not move it (in fact, ~5 attempts to snatch it off via dabbing failed).  Rick captured a few pictures of the "new" features.

At this point we aborted the drag wipe testing and carefully repainted FC back on.  I was very careful to not brush across the large particle nor the "patch" area very much.  I applied very thick ~1 inch long strokes which at first were more like dabs near these areas.  (All other saturated sloppy strokes were ~1-2" in length, repeated.)

I do not think we can drag wipe the full surface (or even the central ~8") of the ETMy-HR.  We were not sucessful in ~25 attempts to get a good pull on the optic except for in the localized areas I mentioned above when I used finger pressue.  And after these attempts we added contaminant to the surface by accident.

The optic size obviously makes it hard to work with.  The working area is too small for 2 hands, elbows, flashlights, your head, etc.  Then, the task is too hampered by suspension brackets and braces to get good surface tension with the flat lens tissue.  The wipe wants to continue to pull off the surface and ripples easily.  As well (or worse), we had a hard time getting the wetted wipe to the surface before the acetone dried.

Rick plans to attach some pictures to this alog so check back later or tommorrow.

 (Doug Jason)
The HAM5 oplvr mirror must have been bumped in situ as we were unable to get the reflected beam out of the viewport to the receiver. It is far enough off that the reflected beam cannot be seen hitting anywhere. We will need to adjust it with the next vent opportunity.

Betsy, Filiberto, Gerardo, Richard, Travis

1. The old vacuum feedthrough was removed by Gerardo
2. Continuity test were done on each pin to verify each section LR, UR, BIAS, UL, and LL.
3. The in-vacuum cables were re-terminated for installation of the new UHV 5-way coaxial connector.
4. Gerardo installed new feedthru (has not been leaked checked).
5. In-vacuum and in-air cables were connected to feedthru.
6. All pins were HIPOT to 1K and passed (some pins had to be reterminated).
6. Pin layout for ESD is as follow:
   Pin 1 - LR
   Pin 2 - UR
   Pin 3 - BIAS
   Pin 4 - UL
   Pin 5 - LL

Fil, Gerardo, Richard, Peter

Attached are 3 photos of the flange that the replacement ESD connectors mate to.  The first image (ESD1.png)
shows some metal shards in the first two pins sockets from the left.  They can be clearly seen in the following
images.

Some of the connections passed the HiPot tester only to sometimes fail when retested.  Some of the connections
that had previously failed, passed.

LVEA: Laser Hazard
Observation Bit: Commissioning  

07:00 Karen & Cris – Cleaning in the LVEA
08:01 Kyle – Soft close on GV5 & GV7. Prep work for door removal of HAM1
08:10 Kyle, Gerardo, Bubba – Removing door on HAM1
08:15 Hugh – Working on CS HEPI system
08:20 Hugh – Taking down HEPI pump in LVEA mezzanine to fix leak
08:48 Aaron – Working on PEM power cables in LVEA
08:50 Filiberto – Going to End-Y to prep for ESD cabling 
09:30 Hugh – Finished with HEPI work and out of LVEA 
09:10 Peter – Going into the H2 PSL enclosure to take pictures
09:19 Doug & Jason – Going into the LVEA to prep for HAM5 OpLev check
10:24 Jonathan – Recycling 2F authentication system
10:36 Karen & Cris – Going to End-Y to deliver garb and clean
10:38 Betsy & Travis – Going to End-Y to work on cleaning ETM-Y 
10:40 Filiberto – Going to End-Y
11:00 Add 200ml water to diode room chiller
12:28 Rick – Going to End-Y
13:08 Cris – Going to End-X to restock garb and turn on small cleanrooms
13:08 Karen – Going to End-Y to restock garb
13:30 Betsy, Travis, and Rick – At End-Y cleaning 
13:35 Adjutant on site for repair work for Kyle 
13:48 Sheila, Elli, and Kiwamu – Going into HAM1 to do alignment 
13:54 Dale – Going to HAM1 to take pictures
14:50 Krishna & Fabrice – Going to End-X to work on BRS system
15:23 Travis – Going into the LVEA looking for Acetone
15:30 Rick, Travis, & Betsy – Going back to End-Y for more optics cleaning
15:48 Sheila – Transitioned LVEA to laser safe
   

The clean room at EX was turned on at approximately 1400 hrs.

Ed ran the PSL DBB scans today. The results are posted below.

Hugh, Sheila, Stefan, Elli, Kiwamu,

The mysterious IMC misalignment event happened again. We are speculating that there may be a loose optical component in the IMC refl path on the HAM2 in-chamber table.

Back in the last February, there was a strange misalignment event in IMC (see alog 10335) where the IMC reflection path seemed to have significantly moved for some reason. This happened again this morning. This time, it was associated with the HAM1 activity of taking the door off from the HAM1 chamber. It tripped the HAM2 ISI and HEPI. After untripping them, we noticed that the IMC reflection was misalgined so much that the beam was almost missing the reflection camera and WFS diodes. However, like the previous event, the IMC power build-up was still reasonably high (it was at 820 counts in MC2 trans which is usually 830 counts or so) when it was locked.  Sheila and Hugh then restored the HEPI back to the previous positions using the IPSs as a reference. At this point we could already see a reasonable DRMI flash at the dark port and also the IM4 trans seemed to have come back to the previous position. Based on these observations, we determined that the misalignment was only in the IMC refl path which is exactly the same conclusion as the previous event. So we realigned the refl path on IOT2L. Now IMC is locking fine and ASC loops were engaged without an issue.

In addition to those recovery activities, we did a brief test where we steered the HEPI by a big amount (~200 urads or so) in each rotational degree of freedom to see if we can reproduce such a big misalignment in the IMC refl, but we could not move the spot on the camera back to the center. Also, we quickly checked the mirrors in the IMC refl path on IOT2L to see if there is a loose component or something easily movable, but we could not find any. The misalignment was mainly in the horizontal direction on the table. The spot position on all three diodes (REFL, WFS_A and WFS_B) had almost the same amount of displacements horizontally, by half a cm toward the East. The attached is 3 hours trend of various sensors. At one point, both the WFSs got misaligned and at the same time the MC1 witness sensors saw a jump in both pitch and yaw (which I think is me untripping the HEPI and ISI).

Add 200ml water to diode room chiller

At the request of Stefan, here are the expected Gouy phases accumulated between mirrors in the SRC. I added the results for PRC for good measure. As we expected, almost all the Gouy phase is accumulated between S/PRM and S/PR2. The model these values were calculated from included 34.5km "thermal" lenses in the ITMs, and no ITM substrate non-thermal lenses. The no ITM substrate lenses is probably close to reality, since the CO2 laser was used to match ITMX to ITMY. Probably the +34.5km thermal lens isn't very true right now though. In general if this lens is not present all Gouy phases get smaller, but the relatve fractions accumulated between optics remain pretty similar.

More sensor correction data. May have posted this before, but I can't find the report. HAM3 shows less coherence with the STS than HAM2. No clue why. If work on the floor stops tripping chambers I'll try to use todays service interruptions for more invasive measurements.

I left the DRMI running last night with the SRC WFS and pointing loop running. We got a 9h lock out of it. But we still have to track down some drift - most likely the recycling cavity, because both 18 and 90 buildups are affected.

Start: 2014/12/16 06:04 UTC
Stop:  2014/12/16 15:41 UTC

HWS ITMy probe beam is reaching the camera.  There is no green beam on the table when this image was taken with the camera.

HWS ITMx beam should be aligned too, I don't have a picture from the ITMx HWS camera yet.

Alexa, Sheila, Stefan

We made a little bit of progress in DRMI alignment today.

 - First we ran the SRY cavity, and commissioned a pointing loop from the ASC_AS_C quad to SRM and SR2.
 - We used M1 (top mass) actuation because we needed the range, so we switched both SRM and SR2 to MO angular actuation.
 - We then carefully tuned the output matrix such that we don't rely on the WFS to keep SR2 and SRM aligned relative to each other.
 - The output matrix is:
             SRM    SR2
    PIT     -7.08   1.00
    YAW      7.12   1.00
   Note that this matrix will likely change if we switch M2 actuation.
 - Then we successfully used this pointing loop in DRMI, even without any SRC WFS running.
 - The gains were H1:ASC-SRC2_Y_GAIN = 1, H1:ASC-SRC2_P_GAIN = 1, and the input matrix is also 1 (H1:ASC-INMATRIX_P_7_27 and H1:ASC-INMATRIX_Y_7_27).

 - Next we re-phased the AS 36 and AS45 diodes using a freely swinging Michelson. A snapshot of all four diodes is attached.
 - Then we started looking into the SRC WFS again:
 - After many failed trials, we noted that one of the biggest signals for the SRM is AS_A_RF36_Q. But we already used this for the BS.
 - However when driving the BS we found that it has a different demod phase: The BS signal is maximized for the mix
    0.89*I + 0.45*Q (all of AS_A_RF36). The same mix was measured for both PIT and YAW.
   Thus we switched the BS to this mix.
 - Finally, for controlling the SRM, we found two signals: AS_A_RF36_Q from before, and AS_B_RF36_I.
 - Because AS_B_RF36_I is more what I expected, I left the SRM on that one.


Not done yet: 
Adding all this to the Guardian. 

[Mackenzie, Paul]

Yesterday we had trouble getting a large enough beat signal between the aux laser and the main PSL. After discussions with Dave O., Stefan and Daniel, we were convinced that the aux laser was not operating monochromatically. This can apparently occur if the aux laser is close to a "mode hop" region when we bring its frequency close to the PSL frequency using the temperature control. We then end up observing the beat frequency between the PSL and one of the "parasitic" modes of the aux laser, which has a much smaller amplitude than the main mode.

On Daniel's advice, we adjusted the diode input current as well as temperature, in order to give us an additional frequency control option that affected the proximity to the mode hopping region differently to the temperature. After some searching around, we suddenly observed a forest of peaks, with one especially large peak.

This forest appears to have been a combination of a) saturation of the 1811 AC output exciting harmonics of the base beat frequency and b) contributions from RF sidebands of the PSL light. We reduced the power on the 1811 using the filter wheel (we ended up using the OD 2.5 filter), resulting in the spectrum shown in the attached figure. The VCO offset frequency was 20MHz. Interestingly, the beat between aux laser and 9, 45MHz sidebands are quite visible.

The dominant beat frequency now registers a -22dBm signal at the AC PD output on the spectrum analyzer, even with the power on the PD attenuated such that the DC output from the PD produced by the PSL beam is less than 1mV (the PSL beam is the weaker of the two beams at the PD). This may still seem a little weak, but it is much better than yesterday, when we had ~-50dBm AC on a ~100mV DC signal.

After some adjustment of the servo box gains, we were able to achieve stable PLL locks. There is no slow temperature servo path included yet, so the PZT on the aux laser will go out of range rapidly if the temperature dial is not adjusted by hand. By adjusting the temperature dial, it was possible to keep the PLL locked for tens of minutes. 

Next, we switched the frequency reference for the PLL offset from the Marconi VCO to the swept sine output of the network analyzer. This presents a new challenge, because now not only does the aux laser have to phase lock to the PSL, but it also has to track the offset frequency generated by the NA. After playing around with IF BW, sweep ranges, source power etc., we were eventually able to get the aux laser to reliably phase lock to the PSL and track the NA frequency through a ~2MHz frequency range (almost enough for a full PRC sweep). We convinced ourselves that the PLL was locked and tracking the NA frequency by observing the TF from NA drive signal to 1811 AC output. When the PLL is locked, the TF is flat, high, and smooth, since the 1811 AC output is coherent with the NA signal at the same frequency. When the PLL is unlocked, the same TF is many decades smaller.

Each time the NA reaches the end of a sweep and flips back to the start frequency, the lock drops. I'm not sure there's much we can do about that. It would help to have the slow path enabled though, in order to compensate for slow drifts of the aux laser frequency away from the PSL frequency. 

Next we plan to try some PRC sweeps if there is PRMI locked time available. For this, we will take the TF from NA drive signal to one of the REFL AIR broadband detectors, with the PRMI locked and the PLL locked. Depending on how that goes, we may pursue the slow temperature feedback development. 

(Doug C and Suresh D.)

    This afternoon we replaced the glitchy diode laser  (Sl. No. 193) in the BS optical lever with a repaired and thermally stabilised laser (Sl. No. 130-1) which was under observation in HAM3 oplev.     The attached plots show the improved performance due to the repairs and stabilisation.

Things to note:

1) Broadband noise injection into pitch has disappeared after swapping the lasers

2) Constant glitching and consequent broadband injection of noise into yaw signals has disappeared after swapping.

3) The RIN has dropped by an order of magnitude at all frequencies

4) The spectrum is stable and does not oscillate between stable and unstable regimes as the temperature in the LVEA changes due to the airconditioners.

Please note that the laser is still approaching a stable operating condition and is under observation for a futher 24 hrs.  However its performance over the past six hours is satisfactory.