IMC calibrated length / frequency path housekeeping

[Jeff, Paul]

I had a look through the calibrated length and frequency paths for the IMC (IMC-X and IMC-F respectively) to check that the calibration is still in order. A description of all the filters in the IMC-X and IMC-F paths can be found in Giacomo's entry 5945.

In fact, some things were amiss in the IMC_X path:

IMC-X_M1 path:

Filters that were engaged: to_m

Filters that are now engaged: dc_cal, wresg1, wresg2, to_m

MC2 M1 feedback is not currently engaged, so this may not matter right now. However, I've engaged the filters that calibrate the IMC-X_M1 signal to M3 motion. wresg1 and wresg2 model the suspension TF from M1 actuation to M3 actuation with the resg damping filters engaged (as they are currently). If and when M1 stage feedback is applied, the corresponding IMC-X channel should be calibrated now.

IMC-X_M2 path:

Filters that were engaged: dc_cal, white, sus_d1, sus_d2, to_m

Filters that are now engaged: dc_cal, wresg, to_m

The sus_d1 and sus_d2 filters are used to model the suspension TF without the resg filter in the M1 L damping path turned on. Because we are now using the resg damping I have switched the sus_d1 and sus_d2 filters off and engaged the wresg filter, which is used to model the suspension TF with the resg filter in the M1 L damping path. The white filter is a filter which was implemented in L1 in an attempt to avoid digitization noise above 50Hz (since the signal is so small there). I don't think we want to have this filter engaged, since it has to be accounted for later in data analysis, and I think we can ignore IMC_X so far above the L to F crossover. I've therefore disengaged this filter. This isn't the first time this one has come back to haunt us: see e.g 5311 or 5452.

IMC-X_M3 path:

Filters that were engaged: dc_cal, white, sus_d, to_m

Filters that are now engaged: dc_cal, wresg, to_m

Same story as for the M2 path.

I took a snapshot of all IMC-X filter banks.

IMC-F path:

Filters that were engaged: cts2V, InvGenFilt, VCO, FtoL

Filters that are now engaged: cts2V, InvGenFilt, VCO, FtoL

The only filter that changed since Giacomo's entry 5945 is the FtoL filter being engaged now instead of the tokHz filter. This means that the IMC_F signal is now calibrated in meters, presumably for ease of comparison with IMC_X. I checked the VCO gain filter: it is still the 536,604 Hz/V value, agreeing with Kiwamu's number from entry 5556 after accounting for the double pass of the AOM.

I had at four separate times (first plot) after these changes were made to see how H1:IMC-X_DQ looked after it didn't appear comparable to LLO last week (see alog 9373). I've also attached a more recent plot of the same channel at LLO (second plot). The same channel still looks quite different between sites and H1:IMC-X_DQ still seems quite featureless in comparison to LLO. A rather naive question...are they meant to look similar?

BSC-ITMX 0.5Hz investigation part2

Arnaud, Sebastien

We've kept investigatiing on the 0.5Hz resonance issue that we've been having on ISI-ITMX (see first alog here). Reminder: we see a  peak at 0.5Hz on all the sensors of the ISI when it is controlled.

After more tests, we realized that this peak appears on all the sensors only when the T240s are in the blend (see plot attached).

Plus, by looking at the T240-X signal, you can clearly see this peak at 0.5Hz. It is even more obvious when the noise floor is reduced (ISI controlled).

 

Thus the issue seems to come from the T240s. We'll continue the investigation tomorrow and find which T240 is bad and how to fix it.

Exactly 0.5Hz (and its harmonics).

PR2 M3 pitch drivealign done

Jeff, Stefan

We did the PR2 M3 pitch L2P decoupling today.

Plot 1:  transfer functions:
 - blue:   measured L2P TF
 - green:  measured P2P TF
 - red:    L2P/P2P (from measured data)
 - black:  fit (note that we paid more attention to the frequencies below 1Hz, because they matter almost 2 orders of magnitude more (see L2P)
 - Purple: fitted filter times measured P2P.


Plot 2: 3e5cts drive to H1:SUS-PR2_M3_LOCK_L_EXC, first at 0.75Hz, then at 0.95Hz. At both frequecies we get about 1 order of magnitude suppression.

HAM4 DTT tf's versus Matlab

Still no resolutions to the problems with HAM4 ISI transfer functions. I took more DTT tf's today, and they all look a little better than the Matlab tf's. The attached plot shows the 3 vertical pods. The 3 thinner lines are the Matlab tf's (which, though not shown, have been repeated 3 times, all 3 times look pretty similar) and the 3 thicker lines (red, green and blue) are the same sensors with a DTT whitenoise tf.

ETMy resuspended

T. Sadecki, B. Weaver

The now final (?) monolithic ETMy Quad has had both chains fully suspended.  Electronics were hooked up and troubleshot for all stages.  OLVs were taken for all stages and MEDM screens updated.  We are satisfied with the current alignment enough that we are ready for the first IAS rough alignment look tomorrow.  We have some rather gross yaw work to do on the main chain, but would like a preliminary look at the overall position on the table so we can take care of any gross, whole structure moves before continuing with finer alignments. 

ops

ETMx ISI Alignment changed

St1 Before	St1 After	St2 Before	St2 After
X 6959nm	41458	-9643	2702
Y 8935nm	9155	253	478
Z -22709nm	-22563	-10660	-10743
Rx 39467nrad	39195	10198	10083
Ry -7904nrad	-5523	5845	7101
Rz 19481nrad	20104	4123	4482

To help make the isolation of the ETMx less troublesome, this morning I reset the ETMX ISI position loop alignment targets to the tilted location.  This way the ISI will not drive back to the untilted position putting larger outputs on the ISI and reliably running up the trilliums, tripping the WDs.  If the local to cart matrices are somewhat correct, the position/alignment change is small & so far OK.  Adding theStage1 & Stage2 cart position changes gives a 46um position shift of the ISI Optical Table with <4urads on the Ry.  All the other dofs combine to 1um or 1 urad or less.  Sheila did spend some time realigning but the ITM wasn't in nominal isolation either so that might have been hampering efforts there.  Once the ITM was Isolated properly, the green locked much better.

So above is the before and afters.

Wiggling cables at ITMx CPS

From ~1400 to 1440--moving ladders, wiggling cables, general trouble making.

ETMy OL values

Betsy swapped all the BOSEMs and AOSEMs on ETMy and left them retracted for open light measurements. The resulting values with gains and offsets are:

prettyOSEMgains('H1','ETMY')

M0F1 30218 0.993 -15109
M0F2 29922 1.003 -14961
M0F3 29480 1.018 -14740
M0LF 31134 0.964 -15567
M0RT 30792 0.974 -15396
M0SD 31110 0.964 -15555
R0F1 31059 0.966 -15529
R0F2 30058 0.998 -15029
R0F3 29953 1.002 -14977
R0LF 30794 0.974 -15397
R0RT 31050 0.966 -15525
R0SD 30282 0.991 -15141
L1UL 29222 1.027 -14611
L1LL 30117 0.996 -15059
L1UR 25735 1.166 -12868
L1LR 22721 1.320 -11361
L2UL 21334 1.406 -10667
L2LL 24582 1.220 -12291
L2UR 21223 1.414 -10612
L2LR 20325 1.476 -10163

I entered the gains, checked that all the outputs were right (should be 15000*0.023333=350) and redid the safe.snap.

 

EX PDH Measurements

(Sheila, Alexa)

We made a few measurements at EX under the following configuration:

PLL Servo Board

• Input 1 pol: NEG
• Input 1 gain: 0dB
• Comm Comp: ON
• Generic Filter: ON
• Fast Option: ON
• Fast gain: -8dB
• Boost 1: OFF
• rest off

PDH Servo Board

• Input 1 pol: POS
• Input  1 gain: -1dB (this was adjusted due to the new modulation depth change...we inserted a 12dB attenuator...see alog 9466. The optical gain must be adjusted accordingly)
• Boost 1: ON
• Comm Comp: ON
• rest off

1. PDH open loop transfer function (EX_PDH_OpenLoopTF_mag/phase.TXT)
2. To calculate the arm cavity length we zoomed in around the FSR resonance (~37MHz) and took the open loop TF (EX_PDH_OpenLoopTF_mag/phase_zoom.TXT). We found FSR ~ 37.752 kHz, which gives a crude estimate of L~3970.6m for the arm cavity length.
3. PDH error signal power spectrum (EX_PDH_Noise.TXT, EX_PDH_Noise_High.TXT, EX_PDH_Noise_Low.TXT). When plotting the power spectrum at full span we noticed a lot of variation in the measurement (we tried to collect the high and low spectrum in this variation). This variation is due to an unstable cavity lock which causes a variation in the optical gain.
4. PDH shot noise (EX_PDH_ShotNoise.TXT)

PSL Change

Kiwamu is transitioning the H1 PSL from commissioning to science mode.

ETMX ISI running fine.

Stefan logged yesterday that he was unable to get the ISI into operation state without tripping.

First time I did this today, I did Stage2 one dof at a time and had no problem.  The ETMx blends at 750mHz on both Stages all dofs.  Pretty sure this isn't as well as can be squeaked from the ISI.  I took this opportunity to take spectra as I brought other blend filters to bare.  Attached is the Stage2 GS-13 X In1 with various filter combos.

Ref3, red: As found 750mHz all dofs both Stages.

Ref7, blue: T(rilliums)750mHz all dofs Stage1, 750mHz Stage2---Maybe a factor of 2 improvement below 0.5Hz

Ref11, green: T250mHz all dofs Stage1, 750mHz Stage2---Much better above 0.5Hz but worse between ~.1 and 0.5Hz.

Ref15,thick brown: T100mHz.44NO Stage1 X Y & Rz else T250s, Stage2 750mHz---Big win below 1Hz to about 0.1Hz.

Ref18, pink:T100mHz.44NO Stage1 X Y & Rz else T250s, Stage2 250mHz---Better ~x2 or 4 above 0.8 but worse below especially 0.2Hz.

Ref23, aqua: T100mHz.44NO Stage1 X Y & Rz plus Notch X Y else T250s, Stage2 750mHz---Lost improvement above 0.8Hz but improves over brown between 0.8 and 0.2Hz.

Ref28, black: T100mHz.44NO Stage1 X Y & Rz plus Notch X Y else T750s, Stage2 750mHz---Some improvements below 0.2Hz and some above 1Hz.

I'm not sure this is exactly the best configuration such as maybe the T250 is better than the T750 for both Stages.  Certainly incrementally there were tradeoffs.  We need to combine the benefits in a better way.

So I have the ISI in this final arrangement. I took the ISI out of Isolation (it triggered then!)  I then reset the ISI targets to the unisolated postions.  The ISI was then able to go into Isolation with 'One Button'.  Green team is evaluating if they can live with this minor alignment change.

ops

Sheila to EX

Commissioning calendar for next 2 weeks

Here is the list of commissioning task for the next 7-14 days:

Green team:

1. Measure difference between red and green locking offsets.
2. Commission the common mode hand-off including the AO path.
3. Make an exact measurement of the cavity length.
4. Complete the noise model for ALS X by adding PDH and COMM servos.
5. Commission a relief script for the angular offsets in the initial alignment controls.
6. Commission the length feedback path to the ETM top suspension point to suppress microseism.
7. Asses the status of the reference cavity temperature controls.

Red team:

1. Angular decoupling optimization for PR2 and PRM.
2. Lock the PRMI using 1f and 5f signals.
3. Lock the PRMI using the 3f signals.
4. Arm cavity alignment for the red beam.
5. Mode matching measurements using ISCT1 and maybe IOT2R.
6. Mode cleaner characterization: Absorption, heating and scattering.
7. Track down the 0.5 Hz feature in the seismic isolation system.
8. Investigate the REFLAIR45 whitening filter issue.

TMS:

1. Repair and exchange the in-vacuum cable for the beam diverter.

ISCTEY (starting next week):

1. Complete the feedthrough panels.
2. Install the on table cabling.
3. Prepare for move to the end station.
4. Check out ALS electronics in EY.