Conlog reads the future

Dave B., Patrick T.

Just realized that the system time for h1conlog is ~ 1 min 42 sec in the future. NTP needs to be set up. We will do this during Tuesday maintenance.

We also added three channels for testing:

H1:PEM-CS_GDS_0_RSET
H1:PEM-CS_GDS_0_SW1
H1:PEM-CS_GDS_0_SW2

WFS sensing matrix

(Jax, Keita)

Yesterday morning we measured the sensing matrix for the ALS WFS. We did this by Injecting 30000cts at 5Hz into H1:SUS-L2_(I/E)TMX_L2_TEST_(P/Y)_EXC, then measuring the transfer function between H1:ALS-X_WFS_(A/B)_I_(PIT/YAW)_OUT and H1:SUS-(I/E)TMX_L3_OPLEV_(PIT/YAW)_OUT. 

In cavity basis:

Pitch Sensing Matrix: (WFS ct/uRad)

	Hard	Soft
A	-24871	-44392
B	-10475	52694

Pitch Input Matrix: (uRad/WFS ct)

	Hard	Soft
A	-2.967e-5	-2.5e-5
B	-5.899e-6	-1.401e-5

Pitch Output Matrix:

0.707	0.707
-0.707	0.707

Yaw Sensing Matrix: (WFS ct/uRad)

	Hard	Soft
A	38421	67629
B	-18263	-25945

Yaw Input Matrix: (uRad/WFS ct)

	Hard	Soft
A	-1.088e-4	-2.838e-4
B	7.665e-5	1.612e-4

Yaw Output Matrix:

0.707	0.707
0.707	-0.707

Raw data: 

Useful information for determining sign conventions from raw data:

1. ETM/ITM Yaw is defined with positive as a counter-clockwise rotation of the optic around the z-axis. 

2. ETM/ITM pitch is defined as positive pitch "down", but ITM oplev is set such that an increase in pitch gives a decrease in oplev measurement.

ETM Yaw:

WFS	dB Magnitude	Phase
A	86.3	126
B	74.7	-46.1

ETM Pitch:

WFS	dB Magnitude	Phase
A	93.79	123.2
B	89.5	-57.8

ITM Yaw:

WFS	dB Magnitude	Phase
A	97.5	-62.58
B	89.9	122.24

ITM Pitch:

WFS	dB Magnitude	Phase
A	82.8	115.7
B	93.0	-60.7

ISCT1 beam size measurement summary

[Evan, Paul]

Here is a summary of the analysis of beam size measurements reported in 9898 and previous, in context with expected parameters from a model of the PRMI.

The first attached plot shows the ITMX direct reflection : PRM direct reflection beam size ratios predicted at the ISCT1 measurement location, as a function of ITMX susbtrate lens and PR2-PR3 distance offset*. The diagonal lines on the plots indicate the measured value of this beam size ratio**. There are also 3 pairs of red and blue vertical lines on the plots. The blue lines represent "cold states" and the red lines represent the designed for "warm state" with a +50km (+20uD) thermal lens in the ITM. The left-most pair of blue and red lines corresponds to the "expected" ITM lens state: -80km (-12.5uD) non-thermal lens in the ITMX substrate. The middle pair of blue and red lines corresponds to the "design" ITM lens state: no non-thermal lens in the ITMX susbtrate. The right-hand pair of blue and red lines corresponds to the "estimated" ITMX lens state, given the assumption that the generalized PRC parameter 2*PR2->PR3 - PR3Rc is as designed.

By assuming PR2-PR3 is as designed, we can estimate an ITMX non-thermal lens of +15uD (6.7km). The estimate from x-axis data and y-axis data agrees very well here. By assuming that the ITMX non-thermal lens is the -12.5uD (-80km) that came from surface figure measurements, we can estimate that the PR2-PR3 offset is +8.82mm. However, it should be noted that other simulation results showed that PRY is very likely to be unstable for such a large PR2-PR3 offset. As far as I'm aware, this was not observed during PRMI commissioning, though I'd appreciate some confirmation if anyone has any. Of course, any combination of PR2-PR3 offset and ITMX lens deviation that gives beam size ratios along the diagonal line is not discounted by these measurements.

The second attaced plots shows the same data for the ITMY measurements, which were taken while 4W was being applied to the ITMY ring heater. For ITMY we have no prior information about the non-thermal substrate lens, so the blue and red lines are not added. The only sensible prior information to assume, just for comparison, is that the non-thermal substrate lens is 0uD (+inf km). This is the right hand edge of the plot. The black dashed line represents the expected substrate lens caused by 4W of heating with the ring heater, using Aidan's number of -13.6uD/W. The diagonal lines again represent the measured beam size ratios. This seems to suggest that the non-thermal substrate lens is around +32uD (31.25km) in the x-axis and +40uD (25km) in the y-axis, again under the assumption that PR2-PR3 distance is as designed. From the ITMX plot and the ITMY plot, we should at least be able to pin down the difference in non-thermal lens power between ITMX and ITMY, even if we can't pin them down individually.

Next, I wanted to take a look at the consequences for actual mode matching in the interferometer, specifically between the IMC and PRX, PRX and XARM.
The third and fourth attached plots shows the IMC-PRX eigenmode overlap and PRX-XARM overlaps respectively over a slightly larger xaxis-range than for the first attached plot, but with the same blue and red lines for ITMX susbtrate lenses. Both diagonal lines from the plots in the first attached figure are included on these mode overlap plots: it is clear that lines from x and y-axes lie very close to each other. The important thing here is that at the "estimated" ITMX non-thermal lens value +15uD and the as-designed PR2-PR3 length, the IMC-PRX overlap is 99.5%(x) and 98.5%(y), and the PRX-XARM overlap is 99.7%(x) and 99.2%(y). If we allow for a +20uD (+50km) thermal lens on top of this value, these overlaps change to IMC-PRX 99.4%(x) 99.8%(y) and PRX-XARM 99.8%(x) 100%(y). In short: IMC-PRX and PRX-XARM should be mode matched well at cold and warm states if we believe the beam size measurements. Of course, the mode matching starts to suffer at a bit lower power than planned as a result of this, but PRX-XARM should still remain >97% for effectively all powers up to 125W. Also worth noting here is that for the mode matching, it doesn't matter right now whether it's the PR2-PR3 length that is off or the ITM non-thermal lens power, since the slope of the mode overlaps with respect to PR2-PR3 offset matches the diagonal lines from the beam size measurements.

I've also been looking at PRX-PRY overlaps for comparison with PRC gain observations as a function of ring heater power, but this post is already too long so I'll post that later.

* PR2-PR3 was varied in the simulation, but for these purposes it's degenerate with PR3 Rc change. The actual quantity that seems to matter most is (2 x PR2-PR3 distance - PR3 Rc), but in the simulation it suffices to vary just one of these. In practice we can only change PR2-PR3 distance so I plot that one.

**One caveat there: since the x-axis PRM measurement is believed to have been affected by the reflection from the back surface of the pick off window, I used the the model value of PRM direct reflected beam size and the measured value of the ITMX direct reflected beam size for computing the ratio. For comparison, the y-axis PRM direct reflected beam size (unaffected by the second reflection form the window) was measured to be 2.15mm, compared to the model value of 2.138mm. This is less than 1% difference, and the PRM model x-axis beam size was scaled by 2.15/2.138 to account for the possible small error in measurement location.

SUS guardian

[Jamie, Arnaud]

Some SUS guardian updates from yesterday :

- all sus guardians have been successfully restarted after Jamie's modifications to SUS.py.

- Sheila thought it would be useful to add a saving feature for the alignment of TMSX with the itmx baffles PD1 and PD4, so align_save_burt was modified to add the option of saving "aligned to pd1" and "aligned to pd4" snap file.

Usage :

./align_save_burt -t alignedtopd1 TMSX
saving alignedtopd1 tmsx
 /opt/rtcds/userapps/release/sus/h1/burtfiles/h1sustmsx_alignedtopd1_offsets.snap

- This has been added to the OPTICALIGN medm screen of TMSX and TMSY as well as the IFO_ALIGN (cf TMSX_OPTICALIGN.png and IFO_ALIGN.png)

- Two states were created for SUS_TMSX and SUS_TMSY ALIGNED_TO_PD1 and ALIGNED_TO_PD4. They simply load the files saved by the align_save_burt script

- Edges between the different alignment positions were added for SUS_TMSX and SUS_TMSY to avoid going through the DAMPED state (which turns off the alignment offsets) during transition between different aligned states (cf TMSX_graph.png)

What need to be done/discussed :

-Turning off the alignment offsets seems to be enough to misalign the suspensions, so I'm wondering if we need to keep the misaligned state (except for PRM)

BS HEPI & ISI Tripped

The SUS tripped out the SEIs and I'm bringing them back up.  After bringing HEPI back I checked the ISI Stage1 position/target deltas and I thought 'Self, you just reset those targets yesterday and they are already drifted too far to start the ISI with the T240 in the blend? Geez!"  So I pondered this for a minute or too and longingly looked again and thought, "Hey self, those deltas aren't as large as they were are they?"  And I replied, "Hey self, you are correct sir! These differences are getting smaller!"  And now over the time to write this alog, the ISI offsets have gotten fairly close to zero and the ISI should go up now directly on the Trilliums.  ANd now that I've tried it did.

Not enough time at the moment to look but either the HEPI is just that slow to settle although looking at the Bias screeen, they are pretty much at target when I still see the ISI offsets too large.  The HEPI could still be relaxing into position even though the Actuator/IPSs are at target or the ISI takes some time to creep into position after the HEPI moves into position.  FYI, the HEPI does move/tilt a fair bit on the BS, not sure why and again it would be good to not do this if the alignment could tolerate it.

BS oplev loop should be automatically disabled when it is tripped

I accidentally tripped the BS suspension and therefore I had to untrip it using the guardian. After bringing it to "damped" and "aligned" states, I noticed that the oplev entered the crazy state where it keeps oscillating (see the attached trend). I believe this is due to some nonlinearity in the error signal particularly when the BS wobbles a lot and I have seen this before.

Anyway, I think that we should tell the guardian to disable the oplev loop when it is down.

BS ISI tripped by LSC feedback on BS suspension

6:32 local (14:32 UTC) -- started feeding back the signal to BS

Immediately after it, the BS ISI tripped. The actuator of stage 1 and GS13 of stage 2 tripped. They had been at level 2. I will try level 1 as Hugh and Fabrice suggested.

REFLAIR_A_RF45 found disconnected at the ISC rack

I plugged it back. This is why I didn't see a reasonable signal out of it.

Red commissioning has started

Arm locking tonight

Sheila, Alexa

After spending the afternoon on the arm locking, we spent some time looking at the COMM handoff.  (Plots coming in the morning...)

• By lowering the PLL gain (to lower the gain peaking frequency) we can get the COMM ugf to 35kHz.  (using PLL gain 19, CM in1 gain 27). 
• The 27kHz line from the end station is large in the COMM error signal as well. (so we wouldn't wat to use a high bandwidth in this loop anyway).
• We then went back to the nominal gains and had a look at the coherence with the OPlevs of our refl control signal, and the COMM control signal.  The ETM motion was higher when we did this, and it had coherence around the pitch resonaonce, the ITM didn't have much coherence.
• We measured some tranfser functions from pitch of the ETM to our control signals, and should be able to use this to make a projection of the frequency noise due to pitch of the ETM. 
• We noticed that the cavity transmitted power fluctuations were much smaller with the dither alignment servos off.  Suspecting clipping, we checked the single show bem position on the camera on ISCT1but it seemed fine. However when we engaged the dither servos the cavity transmitted spot was not centered on the camera.  After a manual realingment the cavity transmitted power seems much more stable. 

 

I am leaving the arm cavity locking, PRM parked and ITMY misalinged, and the alingment servos off. 

ETMX Controls

I have started to study ETMX performance:

- The figure in page 1 shows the ISI motion in the controls configuration that has been used for a week and half or so (Level 2 controls with TCrappy blend filters). Looks like the X signal has been significantly dominated by tilt (see good match of pink and green curves).

- page 2 shows the optical lever pitch motion, it illustrates that most of the RMS is in the .6 to .4 Hz band (nothing new there)

- in this controls configuration, there was a lot coherence between ISI RY signal and the optical lever motion (page 3)

- So I switched Stage 2 to a less aggressive blend configuration. It did not cost any optical lever performance (page 4), but changed the coherence (page 5). The optical lever motion is now coherent with ISI longitudinal motion, which is, I think, much easier to analyze and improve. It allows to implement sensor correction from stage 1 to stage 2.

- I implemented sensor correction from stage 1 to stage 2. It had a good effect on the optical lever motion (page 6). I have started to do some gain and phase margin, but there's room for further improvement.
 
The wind is currently pretty low, so we'll have to wait to find out whether this configuration is more robust against changes of input motions (see past logs on high winds)  

Lines in X arm servo channel

We (CW and Stochastic folks) are starting to look at the HIFO X data. Greg has generated some Fscans using 30-minute SFTs from a long lock stretch of a number of ALS channels, including the one we are treating as our primary "h(t)" for line finding: H1_ALS-X_ARM_IN1_DQ.  The ALS Fscans generated so far are for a long lock stretch (~20 hours) on Feb 2-3  and a 1-day "control segment" on Feb 16 when the arm was not locked.  For defining lock, we require mean(H1:ALS-C_COMM_A_LF_OUT_DQ ) > 1200 counts over a 1-minute period. SFTs require 30 contiguous minutes satisfying this condition. Greg's Fscans can be found at this link. 

I have taken a quick look at the raw integrated spectrum over all of the Fscan SFTs for the 1st kHz of the feedback channel above to see what narrow lines jump out in the Feb 2-3 data. As for the HIFO Y test, there are many lines visible, and presumably more will become visible, once we have more long stretches to integrate over. Here is a tentative list of frequencies that stand out to some degree. More significant digits are given for sharper lines:

18.425 Hz, 27.743 Hz, 48. 52 Hz, 69.2 Hz, 101.6 Hz, 102.1 Hz, 106.4 Hz, 122.1 Hz, 123.5 Hz, 137 Hz, 138.4 Hz, 146.5 Hz, 148.7 Hz, 151.8 Hz, 172.3 Hz, 213.2 Hz, 221.6 Hz, 258.5 Hz, 315. Hz, 317.5 Hz, 322. Hz, 344.8 Hz, 383.7 Hz, 408.4 Hz, 418.5 Hz, 421.2 Hz, 425.7 Hz, 484.5 Hz, 488.4 Hz, 501.5 Hz, 504.2 Hz, 506.7 Hz, 522. Hz, 573.5 Hz, 594.8 Hz, 600.8 Hz, 628.8 Hz, 645.3 Hz, 665.5 Hz, 678.8 Hz, 685.2 Hz,  695.5 Hz, 724.6 Hz, 730.5 Hz, 735.5 Hz, 765.5 Hz, 776.3 Hz, 808.213 Hz, 837.5 Hz, 861.5 Hz

I also took a look at the same channel when the arm was not locked (Feb 16 data) and found a pervasive digital comb (lines are entirely contained in the 0.5-mHz bins) on top of a comb. There is a 100-Hz comb up to and beyond 4 kHz, with a comb of odd-harmonics of 3.125 Hz (=100/32) centered on each 100-Hz harmonic. The spacing between the secondary comb harmonics is 6.25 Hz (=100/16). For example, one sees 190.625 Hz, 196.875 Hz, 200 Hz, 203.125 Hz, 209.375 Hz, with the secondary combs from 200 Hz and 300 Hz joining smoothly at 246.875 Hz and 253.125 Hz. Lines at this strength are not visible in the locked-arm data on Feb 2, but it would be worrisome to future CW searches to have coherent digital lines at even this low level.

More information on H1 HIFO X line-finding plans and tools (e.g. NoEMi) can be found on this wiki page. Comments are welcome.

Figure 1 - minute trends (min,mean,max) of H1:ALS-C_COMM_A_LF_OUT_DQ  on Feb 2 (arm locked to green light)

Figure 2 - uncalibrated spectrum of H1_ALS-X_ARM_IN1_DQ on Feb 2. Power mains marked with 'M'. Single lines marked with 'x'

Figure 3 - uncalibrated spectrum of H1_ALS-X_ARM_IN1_DQ on Feb 16 (unlocked). Power mains marked with 'M'.  The comb-on-comb structure is apparent.

EX PDH Measurements

(Alexa, Sheila, Rana)

PLL Servo Board as per previous alogs..

PDH Servo Board Settings:

• Input 1 enable: ON
• Input 1 polarity: POS
• Input 1 gain: -7dB
• Common Comp: ON
• Boost 1: ON
• Boost 2: ON unless specified

Transfer Functions:

1. Frequency: 24.407363 MHz, Demod phase: 120.7 deg (228 steps): SCRN0343.TXT (mag), SCRN0344.TXT (phase)
2. Frequency: 24.407363 MHz, Demod phase: 140.7 deg (266 steps): SCRN0345.TXT (mag), SCRN0346.TXT (phase)
3. Frequency: 24.407363 MHz, Demod phase: 100 deg (190 steps): SCRN0348.TXT (mag), SCRN0347.TXT (phase)
4. Frequency: 24.407363 MHz, Demod phase: 80 deg (152 steps): GIF 349  ---- each measurement was different
5. Frequency: 24.402363 MHz, Demod phase: 120.7 deg (228 steps): SCRN0354.TXT (mag), SCRN0355.TXT (phase)
6. Frequency: 24.401363 MHz, Demod phase: 120.7 deg (228 steps): SCRN0356.TXT (mag), SCRN0357.TXT (phase)
7. Frequency: 24.387319 MHz, Demod phase: 120.7 deg (228 steps): SCRN0358.TXT (mag), SCRN0359.TXT (phase) --- bistable mode, hops to 01 mode

I have attached two plots summarzing the above results. One plot consists of OLTFs where the modulation frequency was held at 24.407363 MHz and the demon phase as was adjusted (EX_PDH_OLTF_DiffDemodPhase.pdf), while the other plot has the demod phase held at 120.7deg (228 steps), while the modulation frequency was adjusted (EX_PDH_OLTF_DiffModFreq.pdf).

Amplitude Spectrum (from IMON) --- Freqency: 24.407363 MHz, Demod phase: 120.7 deg (228 steps)

1. Boost 2 Off: EX_PDH_NoiseSpectrum_BoostOff.TXT
2. Boost 2 On: EX_PDH_NoiseSpectrum_BoostOn.TXT, EX_PDH_NoiseSpectrum_BoostOn_Low.TXT