Attached are plots of dust counts > .5 microns in particles per cubic foot.

JimW, Alex & Hugh---We forklifted and hefted in 800+lbs onto the HAM3 ISI Optical Table, enough to get it floating.  The Shipping Braces were removed and the Lockers were then locked.  We connected the CPS cabling to the feedthrus in preparation of floating and balancing.  The one missing bolt connecting the ISI to the East Support Tube, Corey noted during ISI Installation, was not successfully installed.  It remains loose and need to be removed and replaced.

HAM3 ISI had payload installed, and the ISI was floated.

HEPI acatuators were craned off of BSC7

Various tests/work done related to the OAT & SUS

EricA & HughR---Keita gave us a window to use the crane from 1130 to 1330, that was nice of him wasn't it!  At least it made for a shorter afternoon.
Anyway, no issues, removed the horizontal and vertical actuators on the two north piers of BSC7.  The main crane was out of position during that time and moving occasionally.  Just the SW corner left and then BSC4.  3/8ths done.

Afterfussing with the setup all afternoon yesterday and another few hours today, I finally glued the first primary prism to the HAM3 PR2. It looks to be off in the d-value disance, but the fixture/microscope setup is such that you cannot check any numbers once the prism is glued and being cured in the fixture.  So, I'll have to wait until tomorrow when the glue is mostly cured to remove the fixture and remeasure everything again.

[Michael R., Guido M., Rick S., Chris M.]

The input optics on the PSL table have been moved from H2 to H1.  The main beam path is aligned up to the bottom periscope mirror which has been left in the cabinet for safety.  All of the auxillary beams are aligned as well, but most of the electronics are yet to be installed (rfpd, dcpd, piezo mirror).  The alignment is as shown in D0902114.  

The periscope spacers have also been moved from H2 to H1 but are actually off in height by 1.25 inches.  New spacers are being machined and should be ready to be installed within the next month.  
We looked at the mode matching into the interferometer using beam scans with the WinCam.  The overap (in power) between the fitted beam and the mode cleaner mode is 98.7%.  The data wasn't robust enough (Rayleigh range is too large) to fit an M^2 value though.  The attached plot Mode_Matching_to_IMC.pdf shows the measured data with fits as well as the ideal beam.  

The H2 EOM has been moved to the H1 table which means that the sideband frequencies will all need to be modified.  Volker Q. will work on this when he is here in the middle of July. Hopefully the final RF system will be in place by then.  

For now we have checked out the AM/PM ratio for the 8.68 MHz sideband.  As usual with RFAM the measurement was not completely conclusive.  We initially measured a value of 4.9e-4, but were able to bring it down to 1.5e-4 by adjusting the alignment on the PD (without any significant change in the DC value).  We also put an iris in front of the PD and by adjusting the aperature size were able to bring it down to 4.9e-5 again without any significant change in the DC value.  Our hypothesis is that it is caused by scattered light possibly from the blocked s polarized beam from the EOM.

Methods of measurement and definitions of modulation indices can be found in an attachment to https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=2901.  The attached spreadsheet H1_PSL_Data.ods contains the data described above.  

J. Kissel, M. Evans

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These are the results and analysis from the Open Loop Gain TF measurements of H2 SUS ETMY mentioned below. For details of the measurement and setup, please check out the associated comments to that entry. 
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In order to check / confirm that the damping loops were "working as expected," I took Open Loop Gain TFs of the degrees of freedom of interest to the excess motion recently found in H2 SUS I/ETMY; Longitudinal (L), Pitch (P), and Yaw (Y). Attached are the results.

Each collection of plots shows the Open Loop Gain TF (in red), and a reference Plant TF (in black). 
The black traces are what we typically loosely call simply "TFs," which are taken from with the excitation point from the out-of-loop TEST bank. These are in OSEM repsonse [ct]s / COIL drive [ct]s, but because all frequency response in the analog signal chain is compensated, the calibration is merely a collection of scale factors; an even scale factor of 60 -- so we can consider it in [m/N] or [rad/N.m] which is indeed the "plant," P, of the damping control loop. 
The new red traces are taken by exciting through the DAMP filter bank, which means the measurement includes the damping filters and gains, -K, and is hence the Plant times the Filters, P*-K == G, or the Open Loop Gain. Here, because we're sensing and actuating from the same point in the loop (i.e. the input to the damp filters), the transfer function is dimensionless, and no calibration is necessary. Also, because the loop is defined with minus sign explicitly outside of the damping filters, the stability criteria is for Upper Unity Gain crossings to stay away from -180, and Lower Unity Gain crossings to stay away from +180. 

These plots confirm what was mentioned below, that with the gains as is [er was by now], the

- L is basically undamped for both SUS, especially its low frequency modes (where the dominant RMS motion lies), because the Open Loop Gain is below 1,
- P is totally squashed (over-damped), especially the higher frequency modes; not necessarily obvious from these plots -- because it's unclear from the open loop gain how much suppression one would get, it merely shows that you have lost of gain over all resonances -- but it certainly obvious from the closed loop TF plots in the previous log.
- Y could maybe use a little more juice at low frequency, but otherwise looks OK


It's from the combination of these plots and the previous plots our "quick fix" recommendation came: it looks like there was plenty of phase-margin head room to increase the gain of the L loop by 10, and decreasing the P gain by a factor of 3 looked like we could still get some gain at the resonances, without squashing them entirely.

Of course, while writing this log, I found that Keita had remeasured the performance using these new "quick fix" gains, and found that the motion has increased. So, I will tuck my tail between my legs and head back to the drawing board with my thinking cap on. l'*sigh*.

J. Kissel, M. Evans

Forgive me while I catch you up to where we are.

Here's some data collected over the course of these SUS's lifetimes thus far. An a priori thanks goes to J. Garcia for taking most of this data!

I collect it all in one place, with the data shown in the mindset of the discussion of why there's so much excess motion in Pitch (during ambient times). I'll show more plots later that show that it's actually Longitudinal that's going nuts, but ... we'll get there.

Remember that both ETMY and ITMY have the same exact filters with the same exact gains.


For now: check out the attached. We will find out that (1) is more useful than (2).
------------
(1) I show a collection of data that is representative of the current situtation, comparing damping loops ON vs. OFF (see allquads_120628_H2SUS_DampingComp_ALLM0_ZOOMED_TFs.pdf). From this plot, we immediately notice the following:

- L is basically undamped for both SUS, especially its low frequency modes (where the dominant RMS motion lies)
- P is totally squashed (over-damped), especially the higher frequency modes
- T, R, V, and Y could maybe use a little more juice, but otherwise look OK -- but even in these DOFs, the lowest frequency modes are poorly damped

These particular filters were designed for the LASTI QUAD, with the gains copied and pasted without really looking at anything more than the ring down time, and (they haven't [changed/been tuned] since Brett's QUAD at LASTI  4 years ago, and therefore what gains were in place in March are still in place now). 

(2) Then, just because cross-coupling came up in conversation, I show the "detail" plots for each of the damped data sets. In particular, take a look at the cross-coupling plots (pgs 7-19) to get a direct measurement of the cross coupling between various degrees of freedom. Note that I've added the Y to L / L to Y plot (pg 13), which is not normally shown because it's not a physically expected cross-coupling. Why? Because we were at one point confused as to whether the excess motion was in Pitch or Yaw. I think, because of the spectra shown yesterday, now we're reasonably convinced that the excess motion during quiescent times is Pitch.

It's admittedly quite difficult to discern and information from these plots, because they're in all sorts of different units... but you can eye-ball it, and see that what cross-coupling does exist is reasonably well below the "diagonal" terms of the transfer function. On the to-do list: make these plots more readable by [converting them into/using] the conversion from rad to m (either modeled or measured).

------------

I'll post a separate log with what I think is going on, with better data to prove it, but I'll say here just in case people are impatient:

- L is totally undamped, both in L and P. The tons of excess motion seen in P at 0.43 and 1.0 Hz are L modes, that, because of fundamental cross coupling are showing up a lot in P. As of yet, we only have a good measure of the test mass P, since we don't have any cavities to measure the L. 
- Because we're overdamping P so much, when those who saw only pitch increased the P gain, the loop went unstable, so we couldn't solve the problem directly.
- From the looks of the open loop gain plots (which will be shown in a separate log, where I'll spell out the problem and solution in greater detail) my proposed "quick fix" solution:
    Decrease the P gain by 3.
    Increase the L gain by 10.
See if that works / helps.
    

OK. I wanna show the open loop plots, so lemme get this up and out, so I can start working on that aLOG.

Just a heads up: while y'all are asleep, I'muna gunna take some active measurements of ETMY, and perhaps gather some quiescent spectra of the TOP stage of TMSY while those are running. I hope to be done in 2 hours, starting from 9:30a ET, 6:30a PT. I have reserved this amount of time on the CDS reserve systems MEDM as well. Please, don't hesitate to call if you need me (617 452 3605) to stop before hand -- otherwise, consider me to be done at 11:30 ET, or 8:30a PT.

It's a shoddy lock, it only lasts for maybe 0.5 sec or so and unlocks, and after 0.5 sec or so it locks again, and this lock/unlock cycle is perfectly in sync with the alignment fluctuation, but it locks nevertheless!

The alignment is not that great, but when it locks we can see a very weak 00-mode spot on the ETM surface at the center of the mirror. Right before it unlocks, the spot shifts in PIT (so my assessment about YAW being a problem might have been wrong).

The real breakthrough was to lock the PLL. You would think that the PLL doesn't matter that much if you lock the laser to the arm, but in reality the frequency noise of Prometheus is so big that it masks things badly. Higher order mode peaks were there but indistinguishable from each other and the demod signal looked like a hopeless random noise hell masking the peaks. As soon as the Beckhoff model was fixed (I don't know why it broke in the first place) and we locked the PLL, we were able to see multiple resonances clearly.

After Jax and Elli somewhat refined the alignment, we turned the PDH lock loop on, and with some tweaking in the gain and sign I was able to find the beam spot on the ETM.

The DC level of the reflected light on the PDH PD is still fluctuating by a large amount, and we confirmed that the fluctuation is NOT from the clipping on the diode by using a power meter in front of the diode. It's not clear where the clipping is happening, it might be the Faraday, or upstream. I'll measure the power fluctuation in the Hartman sensor path tomorrow.

This is good enough of a victory for today.

(corey, jim)

Dial Indicator Install (this work was on Tues)

Dial Indicators used to monitor the HAM3 ISI/HEPI system are roughly in place.  This hardware should not be touched/bumped as it will be used to monitor and ultimately help position the HAM3 ISI. 

Cabling (this work started Wed)

In-Vac Cabling for HAM3ISI is mapped out according to D1002874.  Since Septum work finished up this afternoon, I started running Corner-1 cables to their feed through.  I was able to get all cables to the feedthrough (but opting NOT to screw down to feed-thru), EXCEPT for the H1 Actuator (it's 70" long cable was a foot or so too short!).  At any rate, I only ran cables for Corner-1.  I went to the other side of the chamber and separated Corner-3 cables from Corner-2 (since they're going to opposite sides of the Chamber).  Corner-3 looks like it will be the tough one to work on (due to feed-thru in middle of Chamber).

I labeled the dirty side of feedthroughs.

The dust monitor at location 15 in the LVEA was moved into the clean room over HAM 3 at around noon today. It is labeled 'R'. It seems to occasionally lose communication for a cycle or so. I'm not sure of the cause of this.

Greg, Jim, Hugo,

One could hear/feel both of the top mases resonate when being hit. We moved both masses and set them on a different set of washers (we used the same kind of washer as for the previous units). We adjusted the masses/wahsers position util we could not hear/feel the masses resonate anymore.

TF are running overnight. Hopefully, the unwanted resonances that were recorded in HF are now gone.

(corey, greg, jim)

Spring Pull Down Assys were removed

Actuators were installed; serial numbers noted here.

Payload was put on the Stage-1

• Keel with D071200:  (3)Type-6, (3)Type-4, & (6)Type-5
• 35kg put everywhere a GS13 will go except V1 (it's the only one we have and can install)
• A 600lb & 200 lb Leg Element mass on the Optics Table

Also started some cabling.

(On HAMISI#6, we helped Hugo, as needed)

[Stuart A, Mark B, Jeff B, Vern S]

Whilst last visiting LHO I was able to quickly make some open-light and one dimensional responsivity measurements using three dirty AOSEMs and a test-jig kindly loaned from Mark. The test-jig has previously been used for characterising BOSEMs, and so had to be reconfigured to accommodate the smaller AOSEM coilformer. More importantly, rather than using the rectangular flag employed for the BOSEM, a ~1" long x ~2 mm diameter cylindrical flag was provided by Jeff B.

A UK production Satellite Box (D0901284) was connected up to the AOSEM under test using a dirty in-vacuum quadrapuss harness (D1000234). The Satellite Box was provided with it's required supply lines via a Satellite Box Testing Board (courtesy of Filiberto). For electronics set-up please see image 504 below. A DVM was used to read-out the amplified voltage signal via the diagnostics port (J4) on the Satellite Box (Pins 9 and 28). Note that, the production Satellite Boxes have a input gain of 242k V/A or 0.242 µA/V (double-ended).

Image 506 (below) shows the opto-mechanical set-up for the reconfigured test-jig, including the translation stages and flag assembly. For these tests, only the responsivity is sought, and therefore a one-dimensional characterisation along the sensitive axis is adequate.

When connected up to the Satellite Box, each of the AOSEMs had the following open-light differential voltage measurements:-

- Unit #1, open-light = 14.75 V (i.e. an open-light photo-current of ~61 µA). Corresponds to ~24k counts
- Unit #2, open-light = 10.14 V (i.e. an open-light photo-current of ~42 µA). Corresponds to ~17k counts
- Unit #3, open-light = 12.19 V (i.e. an open-light photo-current of ~50 µA). Corresponds to ~20k counts

Over a ~0.7 mm operating range, these AOSEMs were found to have the following responsivity (see plot below):-

- Unit #1, responsivity = 18784 V/m (i.e. 78 mA/m).
- Unit #2, responsivity = 13028 V/m (i.e. 54 mA/m).
- Unit #3, responsivity = 15721 V/m (i.e. 65 mA/m).

These responsivity results can be compared with the default value we have previously assumed of ~80 mA/m (see LLO aLog entry 2715).

To summarise, these measurements can be used to validate our assumption of using the AOSEM calibration factor of, 1/(80e-3 [A/m] * 240e3 [V/A] * (2^16)/40 [cts/V]) = 3.2e-8 [ct/m], is consistent for units with open-light counts above Jeff K's goal of 25k.