J. Kissel

I've taken a full set of top-to-top transfer functions on H1 SUS ETMX to complete the quick assessment performed on Friday (LHO aLOG 15748) and confirm all is free and good after the recent optic cleaning (LHO aLOG 15744) and door re-install (LHO aLOG 15750). The chamber is still at air, but the doors are on, the ISI is damped, HEPI is floating and position controlled.

Results look great. 

The only thing of interest is that the 2nd pitch mode, previously reported to be a lower frequency than expected (see LHO aLOG 8822) remains low in frequency, and has not changed since the previous assessment. Again, we've controlled this suspension admirably, so no problems. Just one of life's mysteries that remains unsolved.

All data, and updated scripts have been committed to the repository (see below for details).

-----------------
Raw Data:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_L_WhiteNoise.xml
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_P_WhiteNoise.xml
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_R_WhiteNoise.xml
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_T_WhiteNoise.xml
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_V_WhiteNoise.xml
SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_Y_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_L_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_P_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_R_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_T_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_V_WhiteNoise.xml
SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_Y_WhiteNoise.xml

Processed and saved .mat files of measurements:
SAGM0/Results/2014-12-22_1710_H1SUSETMX_M0_DTTTF.mat
SAGR0/Results/2014-12-22_1720_H1SUSETMX_R0_DTTTF.mat

Updated scripts:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/
plotquad_dtttfs.m
plotallquad_tfs.m

PSL Status: 
SysStat: All Green, except VB program offline 
Output power: 33.0w  
Frontend Watch: Green
HPO Watch: Red

PMC:
Locked: 5 days, 14 hours, 35 minutes
Reflected power:    2.3w
Power Transmitted: 23.3w 
Total Power:       25.6w 

FSS:
Locked: 2 days, 15 hours, 58 minutes
Trans PD: 1.944v

ISS:
Diffracted power: 7.44%
Last saturation event: 2 days, 19 hours, 11 minutes  

Will run a couple DC tests to insure clearance.

broken by people starting to go into the LVEA.

Start:   2014/12/22/01:05
Stop:    2014/12/22/17:25
Duration:16h20min

We do see O(1%) power drifts, including a step arounbd 8:30am local - presumably due to human activity. We will chase down where this comes from.

Seismic : Working on ITM configurations
	  Need to take Safe.Snap of BSC1, BSC2, BSC3
	  Calibration of HEPI system pressures	

Suspensions: Clean up after ETM optics work

no restarts reported for both days. Conlog frequently changing channels reports attached.

Evan, Stefan

With the winds calming down again, we did some more SR3 alignment work:
- We noticed that for SCR1_Y AS B 36 I is still the best signal. It has
   - less "phase lag", presumably due to a reduced coupling to the BS. This allows us to do a high bandwith loop.
   - a small enough offset that servoing it to zero makes sense for reducing build-up fluctuations.
- Thus we closed the yaw loop with a UGF of 3.3Hz. Engaging it is in the Guardian.
- We tried to play the same game for the pitch loop, with less sucess.
   - all signals have some RF offset.
   - none of the signals seem to have low enough "phase lag" for a high BW loop. We should make sure this phase lag is not due to some broken whitening filter.
- Thus for now we left pitch in the configuration described in alog 15769.

Evan is now also updating the WFS relieve.

We will leave DRMI locked for the night.

I went into the PSL to check out possibilities for redoing the top periscope piezo mirror mount, which I think is responsible for the 250 Hz peak in DARM at LLO (Link). The secondary purpose was to check the recovery time for a 10 minute incursion. The IMC did not loose lock but suffered intensity spikes beginning when I went in, and quickly dissapating so that they were gone by an hour after I left. The plots show MC2 TRANS and ISS_AOM_DRIVER_MON in an overview and a zoom into one of the intensity spikes. The zoom suggests ISS oscillations. The step in MC2 TRANS was when Evan, seeing the spikes, shut down the gaurdian. 

Robert, Evan

Elli, Thomas, Stefan

- We found that the DRMI build-up fluctuations reported in alog 15765 were mostly due to a small offset in the WFS locking point for the SRC (feed back to SRM yesterday, switched to SR3 today).
- We fine-tweaked the input matrix mixing signals from AS36 A (orthogonal to the BS signal) and AS36 B (I&Q), such that we maximize the SR3 signal and get a good locking-point offset.
  The matrix is:
    AS A RF36I -0.45
    AS A RF36Q  0.89
    AS B RF36I  1.1
    AS B RF36Q -0.77
  This was found for pitch. Yaw was confirmed to be close, but wind prevented further fine-tuning. Using this significantly reduced the build-up fluctuations.

- Next we commissioned the a high BW loop for SR3. The filters are
    PIT: zpk([0.06+i*0.815;0.06-i*0.815;0.3+i*3.25;0.3-i*3.25],[0.3+i*2.87;0.3-i*2.87;11.1111+i*38.4258;11.1111-i*38.4258],1,"n")
    YAW: zpk([0.13+i*1.24;0.13-i*1.24;0.15+i*2.88;0.15-i*2.88],[0.15+i*2.48;0.15-i*2.48;11.1111+i*38.4258;11.1111-i*38.4258],1,"n")
  They were successfully tested up to a UGF of 6Hz using an optical lever. However, on the WFS we could not go that high because there was significant cross-talk from the other loops.
  Thomas will attach a measured transfer function.

- We left the feed-back on SR3 (the guardian sets this up), but with maybe 10 times lower BW.

- We also noticed that the high BW WFS cause more violent lock losses. We thus put (generous) limiters to all the top stages.

Unfortunately the winds are at 60mph again, so we won't leave it locked tonight.

I have reconfigured conlog to remove the constantly noisy H1:ALS-Y_VCO_TUNEOFS and the 2 disconnected channels. Details are:

+ H1:ALS-X_WFS_AUTOC_SWITCH

+ H1:ALS-Y_WFS_AUTOC_SWITCH

- H1:ALS-X_WFS_AUTOC_SWTCH

- H1:ALS-Y_VCO_TUNEOFS

- H1:ALS-Y_WFS_AUTOC_SWTCH

inserted 2 pv names

deleted 3 pv names

model restarts logged for Fri 19/Dec/2014
2014_12_19 11:28 h1fw1
2014_12_19 14:48 h1hpiham3
2014_12_19 14:49 h1isiham3

h1fw1 unexpected restart, SEI HAM3 restarted to see if it would fix a problem. Conlog frequently changing channels report attached.

Stefan, Kiwamu,

We did some more ASC optimizations tonight in DRMI. We are leaving the DRMI locked overnight to see what drfits on a time scale of hours.

Here is a list of what we did:

• High bandwidth PR3 and PRM ASC loops were engaged. Both use the M3 bottom stage with an almost 1/f open-loop shape.
  • PR3 loops = 6 Hz UGF,
  • PRM loops = 1 Hz UGF (going above this UGF causes instability at 10 Hz for some unknown reason )
• Off-loading to top stage on PRM, PR3 and BS are newly implemented. The top stages have an integrator so that they keep the DC value when the DRMI drops lock.
• IM4 pointing slow loop is newly engaged. It uses ASC-POP_B. The output matrix is diagonalized with an off-diagonal element for PRM.
  • for pitch output matrix, IM4 = 1 and PRM=22.
  • for yaw output matrix, IM4 = 1 and PRM = 129.
  • The servo points to a non-zero point on POP_B as we were not sure whether it was a good idea to servo it to zero without confirming the arm pointing. In addition, we saw the build-up dropping when we went further away from the nominal offset point, which is another reason why we did not servo it to zero. For now, we put an offset in ASC-POP_B_PIT(YAW)_OFFSET such that we don't loose the current IM4 pointing.
• We moved SR3 (which is one of the uncontrolled mirrors) to see what signal responds to it. It seems that REFL_B_45I is sensitive to this mirror, but currently SRM is suppressing this sensor with a slow bandwidth. Stefan will look into this mirror during the weekend.

All the modifications and new loops are coded in not only in the ISC_DRMI guardian but also ISC_DOF guardian so that they do not mess up the initial alignment WFSing.

Last night I tried a new loop topology for the OMC alignment servos, using the inputs to the OMC SUS that were added to the model a few weeks ago.

The idea here is to diagonalize the DC alignment in HAM6, using OM1 and OM2 for the centering on the AS WFS, and use OM3 and the OMC SUS for the centering into the OMC.

I measured the sensing matrix for OM3,OMCS {P,Y} --> OMC-ASC ANG,POS {X,Y}, took the inverse, and used this for the output matrix (DOF2TT).  This kind of worked; I was able to close all four loops and engage the AS WFS DC centering in parallel.  But the centering on the OMC wasn't very stable, and turning on the integrators caused an instability in the yaw loops.  I think the problem is that we're using loops designed for the tip-tilts to actuate on a 2-stage suspension; a better approach is to invert the OMC SUS --> OMC QPD transfer function and put this into the OMCSUS ASC filter banks.  But, my earlier fear that the OMCSUS actuation was too weak doesn't appear to be true.  This scheme should work once we account for the complications in the OMC SUS transfer function.

A screenshot of the output matrix from ANG,POS --> OM3, OMCS is attached.  You can see that the OMCS is 1000x weaker than the tip-tilt.  For now I have reverted to the old configuration, which uses OM1 and OM2.

After I reverted back I noticed that the dither loops had developed an instability!  They were stable as recently as 10 days ago, according to conlog nothing had changed.  We'll need to investigate the dither alignment chain in the new year.

[Mackenzie, Eleanor, Paul]

This afternoon we got the PLL aux laser measurement up and running, and fortunately this happened to coincide with a locked DRMI. 

We were initially able to observe the FSR dips, as we had seen them previously. We decided since we had the benefit of a locked DRMI we would try adding the clipping objects in the aux laser input path, and also in front of the REFL AIR B diode that was used to detect the beat note between the aux laser reflected from the PRM and the PSL beam reflected from the PRM. 

We observed new features in the transfer function, which are likely candidates for higher-order mode resonances. Attached are two preliminary plots of sweeps close to two FSR HG00 resonances.

A very quick calculation of the PRC one-way Gouy phase from these data is as follows:

HG00 peak resonance frequency - HG10 peak resonance frequency = 0.3MHz.

Fraction of FSR = 0.3/2.6 = 0.1154.

Convert to degrees one way Gouy phase: 0.1154*180 = 20.77degrees.

With the ITMs that are currently installed, we expect a one-way Gouy phase in the PRC of about 18 degrees (with no ITM thermal lensing). Design value accounting for thermal lens in ITMs from 18W input power and 0.5ppm absorption on the ITM HR surface is 25 degrees. 

Worth noting is that the DRMI was locked during this measurement, not the PRMI. It's not clear to me yet how this affects the results – maybe not much. Also, evidence for the additional peaks really being due to HOMs is the repeated resonance a further 3MHz away from the HG00 resonance, which I expect is the HG11+HG20+HG02 mode resonance. More precise analysis and measurements to follow. 

Thomas, Stefan, Jeff, Kiwamu, Elli

Continuing along the same line as yesterday's work on PR3 (alog 15727), we have designed high-bandwidth (<10Hz) actuation filters for the PRM.  These filters are applied to H1ASC-PRC1P and H1ASC-PRC1Y in the central part of the ASC WFS servo.

The filters added to ASC WFS central are called 'PRM^-1' and are:
H1:ASC-PRC1_P:   zpk([0.2+i+0.9;0.2-i*0.9;0.05+i*3.41;0.05-i*3.41],
                [0;0.2+i*2.75;0.2-i*2.75;0.125+i*9.99922;0.125-i*9.99922],1,"n")
H1:ASC-PRC1_Y:     zpk([0.04+i*1.08;0.04-i*1.08;0.1+i*2.08;0.1-i*2.08;0.05+i*3.43;0.05-i*3.43],
                [0;0.15+i*1.8;0.15-i*1.8;0.05+i*3.3;0.05-i*3.3],1,"n")
Some old unused filters were also removed.

Low-pass filters called 'RLP17' were added to the PRM M3 locking filters in pitch and yaw:
H1:SUS-PRM_M3_LOCK_P:  zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")
H1:SUS-PRM_M3_LOCK_y:  zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")