Koji and Steve pointed out that previous design  of a damping bracket was a bit complicated to manufacture. So I made it simpler and also added a tap hole for original yaw damping. We'll give drawing to Mike in the machine shop tomorrow morning.

I've purchased K&J magnets for eddy current damping, they should be here in 2 days. 

We went into the vertex today to see about fixing the alignment.  The in-air access connector is in place, and we took heavy doors off of BS, ITMY, and ETMY chambers.

We started by looking at the pointing from the PZTs.  Manasa and Raji hooked up HV power supplies to the PZTs and set them to the middle of their ranges (75 V).

We installed a target on the BS cage, and new "free standing" targets made special by Steve for the SOSs on ITMY and ETMY.

Using a free-standing aperture target we looked at the beam height before PZT2.  It was a little high, so we adjusted it with PZT1.  Once that was done we looked at the beam height at PR2, and adjusted that height with PZT1.

We then tried to use the hysteresis in PR2 to adjust the beam height at ITMY.  Pushing just a little bit at the top or bottom of PR2 would repoint the beam in pitch.  This sort of works, but it's stupid.  Using this method we got the beam more or less centered vertically at ITMY.

We moved on to ETMY with the idea that we would again use the hysteresis in PR3 to get the vertical pointing to the ETM correct.  This was a good demonstration of just how stupid the tip-tilts really are.  Just touching slightly at the top or bottom or PR3 we could completely change the pointing at ETMY, by mili-radians (~4 cm over 40m).

At this point I cried foul.  This is not an acceptable situation.  Very little stimulation to the tip-tilts can repoint the beam inside the PR cavity.

Steve says that the TT weights, which will attach to the base of the TT mirror mounts and should help keep the mirrors vertical and not hysteretic, are being baked now and should be available tomorrow.  We therefore decided to stop what we were doing today, since we'll have to just redo it all again tomorrow once the weights are installed.

 [Raji, Manasa]

The high-voltage power supply from the OMC was removed to replace one of the PZT power supplies. The power supply terminals were connected to the rear connection ports as per instructions from the manual (TB1 panel: port 3 - (-)OUT and port7 - (+)OUT). They were both switched  on and set to deliver (75V) to the PZTs.

 We also wrote down the serial numbers (top center of each TT, inscribed by hand) for what tip tilt is installed where.  I then went through the elog to determine which TT was suspended with what kind of wire (thick or thin).  Summary: all installed tip tilts have thick wire, 0.0036" diameter.

As noted in elog 3295, we had found that there was similar hysteresis whether we used the thick or the thin wire, so we had decided not to go back and re-suspend every optic.

Also, since we will redo the pitch balance tomorrow with the new hardware tomorrow, I think we should put in the new LaserOptik mirrors at the same time.  We have not yet gotten phase maps of them, but we might as well do this rebalancing once, rather than twice.

 Den mentioned that the disks will have threaded holes, and that he has made a note to that effect on the paper copy of the drawing that he will bring to Mike at the shop.  Also, all threaded holes in the new plate are marked on the paper copy.

 This means that the low voltage dual supply which was wired in series (so could supply a max of 63V = 2*31.5V) has been replaced with the OMC power supply.  This is okay since we haven't turned on the OMC PZTs in a long, long time.  This is *not* the power supply for the output pointing PZTs.  When she says "both", she means the new HV supply, as well as the HV supply that was already there, so both pitch and yaw for PZT2 are being supplied with 75V now.

Wow... This is even more complicated than the original "Y" design...

 While I was doing the oil change of the roughing pumps I accidentally touched the 24 V adjustment knob on the power supply.

All valve closed to default condition. I realized that the current indicator was red at 0.2A  and the voltage fluctuated from 3-13V

Increased current limiter to 0.4A and set voltage to 24V     I think this was the reason for the caos of valve switching during the VME swap.

Jamie has arranged for phase map measurements this afternoon, so I will take the 6 dichroic LaserOptik optics over to Downs at 1:15 this afternoon.

Team Jamie+Nic will lead the effort to clamp down dog clamps as placement markers for all 4 in-vac passive TTs, and then pull all 4 TTs out of the chambers.  They plus Den will move the TTs to the Cleanroom, and will start to install the new pitch alignment hardware. 

When I return with the optics, we will install them in the TTs and re-balance them.  Then we can put them back in the chambers and get back to work on alignment.  

After we re-install the TTs, we will need to check the leveling of all 3 corner tables, just to be sure.

Previous results
I am measuring the noise level of the microphones. The circuit does not seems to limit their sensitivities but the circuit's noise seems to be different from other channels.

Measurement
I measured the circuit noise of all 6 channels. (input open)
(mic_open.png)
The noise level is about 10 times different from the others.

Comparing the acoustic signal, microphone+circuit noise, and ADC noise;
(mic_noise.png)
- blue; acoustic signal
- green; microphone+circuit noise
- red; circuit (the data was not took simultaneously.)
- sky blue; ADC noise

To do
I will remake the circuit though the circuit does not limit the sensitivity. I would like to make sure that the circuit does not affect badly and to make the circuit noise level the same.
At the same time, I will get the PMC control signal and see coherence between it and acoustic sound.

 Raji took the optics over. They were all measured at 0 deg incidence angle, although we will use them at the angles required for the recycling folding mirrors.  Here's the summary from GariLynn:

In general all six pieces have a radius of curvature of around -700 meters.

  We have to change the sample rate and AA filter for the mic channels before going too far with the circuit design.

 To save the mic channels at higher than 2k (which we should do), we either have to move them to a different model, change the rate of the PEM model, or see if you can save data faster than the model runs (which I can't imagine is possible).

Quote:

Raji took the optics over. They were all measured at 0 deg incidence angle, although we will use them at the angles required for the recycling folding mirrors.  Here's the summary from GariLynn: In general all six pieces have a radius of curvature of around -700 meters. They all fall off rapidly past 40 mm diameter.  Within the 40 mm diameter the rms is ~10 nm for most.  I can get finer analysis if you have something specific that you want to know.    All data are saved in Wyko format at the following location: http://www.ligo.caltech.edu/~coreopt/40MCOC/Oct24-2012/ Gari

 After a long search, I've found a way to finally read and analyze(?)  the Wyko opd format data using Image SXM, an image analysis software working only on mac osx.

I am attaching the images (in tiff) and profile plot of all the 6 mirrors.

We removed all the folding mirrors ({P,S}R{2,3}) from the IFO and took them into the bake lab clean room.  The idea was that at the very least we would install the new dichroic mirrors, and then maybe replace the suspension wires with thinner ones.

I went in to spend some quality time with one of the tip-tilts.  I got the oplev setup working to characterize the pointing.

I grabbed tip-tilt SN003, which was at PR2.  When I set it up it  was already pointing down by a couple cm over about a meter, which is worse than what we were seeing when it was installed.  I assume it got jostled during transport to the clean room?

I removed the optic that was in there and tried installing one of the dichroics.  It was essentially not possible to remove the optic without bending the wires by quite a bit (~45 degrees).  I decided to remove the whole suspension system (top clamps and mirror assembly) so that I could lay it flat on the table to swap the optic.

I was able to put in the dichroic without much trouble and get the suspension assembly back on to the frame.  I adjusted the clamp at the mirror mount to get it hanging back vertical again.  I was able to get it more-or-less vertical without too much trouble.

I poked at the mirror mount a bit to see how I could affect the hysteresis.  The answer is quite a bit, and stochastically.  Some times I would man-handle it and it wouldn't move at all.  Sometimes I would poke it just a bit and it would move by something like a radian.

A couple of other things I noted:

• The eddy current damping blocks are not at all suspended.  The wires are way too think, so they're basically flexures.  They were all pretty cocked, so I repositioned them by just pushing on them so they were all aligned and centered on the mirror mount magnets.
• The mirror mounts are very clearly purposely made to be light.  All mass that could be milled out has been.  This is very confusing to me, since this is basically the entire problem.  Why were they designed to be so light?  What problem was that supposed to solve?

I also investigated the weights that Steve baked.  These won't work at all.  The gap between the bottom of the mirror mount and the base is too small.  Even the smalled "weights" would hit the base.  So that whole solution is a no-go.

What else can we do?

At this point not much.  We're not going to be able to install more masses without re-engineering things, which is going to take too much time.  We could install thinner wires.  The wires that are being used now are all 0.0036", and we could install 0.0017" wires.  The problem is that we would have to mill down the clamps in order to reuse them, which would be time consuming.

The plan

So at this point I say we just install the dichroics, get them nicely suspended, and then VERY CAREFULLY reinstall them.  We have to be careful we don't jostle them too much when we transport them back to the IFO.  They look like they were too jostled when they were transported to the clean room.

My big question right now is: is the plan to install new dichroics in PR2 and SR2 as well, or just in PR3 and SR3, where the green beams are extracted?  I think the answer is no, we only want to install new dichroics in {P,S}R3.

The future

If we're going to stick with these passive tip-tilts, I think we need to consider machining completely new mirror mounts, that are not designed to be so light.  I think that's basically the only way we're going to solve the hysteresis problem.

I also note that the new active tip-tilts that we're going to use for the IO steering mirrors are going to have all the same problems.  The frame is taller, so the suspensions are longer, but everything else, including the mirror mounts are exactly the same.  I can't see that they're not going to suffer the same issues.  Luckily we'll be able to point them so I guess we won't notice.

When installing the dichroics we need to pay attention to the wedge angle.  I didn't, so the ghost beam is currently point up and to the right (when facing the optic).  We should think carefully about where we want the ghost beams to go.

I also was using TT SN003, which I believe was being used for PR2.  However, I don't think we want to install dichroics in the PR2, and we might want to put all the tip-tilts back in the same spots they were in before.  We therefore may want to put the old optic back in SN003, and put the dichroics in SN005 (PR3) and SN001 (SR3) (see 7601).

 PEM model is running at 64K now. It turned out to be tricky to increase the rate:

• BLRMS are computationally expensive and original pem model did not start at any frequency higher then 16k ( at 16k cpu meter readings were 59/60 ). Also when we go higher then 16k, front-end gives the model less resources. I guess it is assumed that this model is iop and won't need too much time. So in the end I had to delete BLRMS blocks for all channels except for GUR2Z and MIC1.
• Foton files are modified during model compilation: lines with sampling rate and declaration of filters in the beginning of the file are changed only. Sos-representation and commands are the same. I hoped that filter commands will let me change sos-representation quickly. I've opened Foton and saved the file. However, Foton modified commands in such a way that the ratio of poles and zeros to sampling rate is preserved. I guess all filters have to be replaced or this process should be done in another way.
• BLRMS block uses low-pass filters below 0.01 Hz, increasing the sampling rate by a factor of 32 might make calculations incorrect. I'll check it.

We should also increase cut off frequency of the low-pass filter in the microphone pre-amplifier from 2 kHz up to ~20-30 kHz.

 Great, however, unless you can save the images in FITS format, we still need another reader for the opd images.

Previous phasemap data and analysis for the new 40m COC are summarized on the following page

https://nodus.ligo.caltech.edu:30889/40m_phasemap/

(Use traditional LVC authentication (not albert.einstein))

The actual instance of the files can also be found on nodus below the following directory:

/cvs/cds/caltech/users/public_html/40m_phasemap

The programs for the analysis are found in

/cvs/cds/caltech/users/public_html/40m_phasemap/40m_PRM/mat

The main program is RunThis.m

Basically this program takes ascii files converted from opd by Vision32.
(i.e. You need to go to Downs)
Then the matlab program takes care of the plots and curvature analyses.

The thinner wire has a history that it did not improve the hysteresis (ask Jenne). Nevertheless, it's worth to try.

If you flip the clamp upside-down, you can lift the clamping point up. This will make the gravity restoring torque stronger.
(i.e. Equivalent effect to increasing the mass)

Luckily (or unluckily) the clamp has no defined location for the wire as we have no wire fixture.
Therefore the clamp will grab the wire firmly even without milling.

 Why not? The new dichroic mirrors have more transmission of 1064nm than G&H. Thus it will give us more POP beam and will help locking.

 The wire clamps should be taken off at the top and at the mirror holder. They need a mill touch up. It would be nice to have the centering jig from LLO for the 0.0017"

The clamps in this condition are really bad. It can sleep, it is not adjustable.

 The second loop of the bungee cord should be on the top of the acrylic  and still on the supporting aluminum tube as shown.

 Thank you for changing the sample rate!
Also we have to change the Anti-Aliasing filter, as Jamie said.

Now my question is, whether S/N ratio is enough at high frequencies or not. The quality of EM172 microphone is good according to the data sheet. But as you can see in previous picture, the S/N ratio around 1kHz is not so good, though we can see some peaks, e.g. the sound that a fan will make. I have to check it later.
And, is it possible to do online adaptive noise cancellation with a high sampling rate such that computationally expensive algorithms cannot be run?

  That's no good - we need BLRMS channels for many PEM channels, not just two. And the channel names should have the same name as they had in the past so that we can look at long term BLRMS trends.

I suggest:

1. Have a separate model for Mics and Magnetometers. This model should run at 32 kHz and not have low frequency poles and zeros. Still would have acoustic frequency BLRMS.
2. Have a low frequency (f_sample = 2 kHz) model for seis an acc. Seismometers run out of poop by 100 Hz, but we want to have the ACC signal up to 800 Hz since we do have optical mount resonances up to there.
3. Never remove or rename the BLRMS channels - this makes it too hard to keep long term trends.
4. Do a simple noise analysis to make sure we are matching the noise of the preamps to the noise / range of the ADCs.
5. Immediately stop using bench supplies for the power. Use ONLY fused, power lines from the 1U rack supplies.

Ayaka, Den

 C1PEM model is back to 2K.

We created a new C1MIC model for microphones that will run at 32K. C1SUS machine is full, we have to think about rearrangement.

For now, we created DQ channels for microphones inside iop model, so we can subtract noise offline.

We provided 0-25 kHz bandwidth noise to AA board and saw the same signal in the output of ADC in the corresponding channel. So cut-off frequency is higher then 25 kHz. There is a label on the AA board that all filters are removed. What does this mean?

We've turned off AA bench power supply, prepare to use fused from 1U.

I measured the transmitted power @1064nm on one of the LaserOptik mirrors labled SN6

Here is the data

The mirror is not a good reflector at 0 deg.

Jamie and I spent some time with tip tilt SN001 this afternoon.  This was installed as SR3, so I was going to put a new LaserOptik mirror in there.  I accidentally snapped one of the wires (I forgot how strong the magnets are - one zipped from the mirror holder and captured the wire).  Jamie and I put the new LaserOptik mirror in, with the wedge correct, but we need to re-resuspend it with the 0.0036" wire tomorrow.  We'll also keep working on re-pitch aligning the other optics.

PR2 needs to be put back as a G&H, and we need to put a LaserOptik mirror into PR3.

 We now stop using bench DC power supplies for microphone preamp and PEM AA board. DC power is wired from 1x5 rack suppliers. I've installed a beam to mount fuse houses in the 1x7 as we did not have one.

Now that I read Koji's last elog about phase maps, I am not sure if these are still required, but here they are (the tilt-removed phase maps of the Laser Optik mirrors), first 1, 2, 3:

Then 4,5,6:

So they all have an elevated center. I am not sure why the phase maps of mirrors 5 and 6 are slightly smaller in dimension. Anyhow, all mirrors have quite strong aberrations. Also, there is no big difference between the mirrors. Check for yourself, but be careful with the colors since the scales are all different.

Are these maps drawn from the data we extracted using Image SXM??

 Indeed. So the only manipulation that I did was to remove the tilt (since this should usually be seen as an artifact of the measurement, or better, we can assume that tilt is compensated by alignment). I did not remove the curvature.

 We resuspended SN001 this morning with 0.0036" wire.  We did as Koji suggested, and flipped the wire clamp so the suspension point is a little higher, so we'll see if that helps.  We put LaserOptik mirror SN1 into this TT001.

We put the G&H mirror back into TT004, which is PR2.  We also put a LaserOptik mirror (SN5) into TT005, which is SR3.

Jamie is working on re-pitch aligning TT004 and TT005 (we already did 001), then we can re-install them in the vacuum system later this afternoon.

 The tip tilts have all been pitch-adjusted now, and they have all been put back onto the tables, with the same serial numbers in the same places as we took them out.  Jamie also re-leveled the BS table.

Raji and I will align things after I finish measuring the MC spot positions.

[Raji, Jenne]

After lunch we began where Raji and Jamie had left things.  PR2 was unfortunately pitched down so far that it was almost hitting the table just in front of PR3.  I loosened the 4 clamp screws that hold the wire clamp assembly to the mirror holder, and tapped it back and forth until I was within hysteresis range, re-tightened, then tapped the top and bottom until we were at the correct beam height just in front of PR3.  I also had to unclamp it from the table and twist the base a tiny bit, since the beam was closer to hitting the beam tube than the optic.  Finally, however, PR2 is adjusted such that the beam hits the center of PR3.

Moving on to PR3, the pitch looked good while we were looking at the aperture placed near the face of ITMY, so we left that alone.  The beam is off in yaw though.  Several times I unclamped the tip tilt from the table, and twisted it one way or another, but every time when I tighten the dog clamps, I'm too far off in yaw.  The beam points a little too far south of the center of ITMY, so we were putting the beam a little north of the center before I clamped it, but even tightening the screws in the same order, by the same amount each time, causes a different amount of slipping/twisting/something of the TT mount, so we never end up directly in the center of the ITM.  It seems a little like a stochastic process, and we just need to do it a few more times until we get it right. 

We left it clamped to the table, but not in it's final place, and left for JClub.  On Monday morning we need to go back to it.  As long as we're pretty close to centered, we should probably also have someone at ETMY checking the centering, because we need to be centered in both ITMY and ETMY.

We have not touched the SR tip tilts, so those will obviously need some attention when we get to that point.

[Raji, Ayaka]

Thanks to Den, power supplies for microphone circuit are changed.
So I measured the microphone noise again by the same way as I did last time.

  solid lines: acoustic noise
 dashed lines: un-coherent noise
black line: circuit noise (microphone unconnected)

The circuit noise improves so much, but many line noises appeared.
Where do these lines (40, 80, 200 Hz...) come from?
These does not change if we changed the microphones...

Anyway, I have to change the circuit (because of the low-pass filter). I can check if the circuit I will remake will give some effects on these lines.

I do not think that 1U rack power supply influenced on the preamp noise level as there is a 12 V regulator inside. Lines that you see might be just acoustic noise produced by cpu fans. Usually, they rotate at ~2500-3000 rpm => frequency is ~40-50 Hz + harmonics. Microphones should be in an isolation box to minimize noise coming from the rack. This test was already done before and described here. 

I think we need to build a new box for many channels (32, for example, to match adc). The question is how many microphones do we need to locate around one stack to subtract acoustic noise. Once we know this number, we group microphones, use 1 cable with many twisted pairs for a group and suspend them in an organized way.

 Maybe we have already discarded this idea, but why not do the alignment without the MC?

Just lock the green beam on the Yarm and then use the transmitted beam through the ITMY to line up the PRC and the PZTs? I think our estimate is that since the differential index of refraction from 532 to 1064 nm is less than 0.01, using the green should be OK. We can do the same with the Xarm and then do a final check using the MC beam.

In this way, all of the initial alignment can be done with green and require no laser Goggles (close the shutter on the PSL NPRO face).

 I do not think they are acoustic sounds. If so, there should be coherence between three microphones because I placed three at the same place, tied together. However, there are no coherence at lines between them.

 [Jan, Manasa]

Below are phasemaps for the tip-tilts with both tilt and RoC removed. We have not used Koji's code; but tweaked the earlier code to remove curvature.

The RoC values matched approximately to that quoted by Gari Lynn ~700m.

Phasemaps

The color scale for height are not the same for all mirrors.

SN1, SN2 and SN3

SN4, SN5 and SN6

 The posted residual phase maps show circular contours since the data came with relatively low resolution in height. This is ok for what we want to do with these phase maps (i.e. simulating higher-order mode content in the PRC using Finesse). Better resolution is only required if you want to understand in detail optical scattering out of the cavity. Anyhow, the circular artifacts can be removed by first interpolating the phase maps to a higher lateral resolution, and then performing tilt and curvature subtraction. So we will soon have better looking phase maps posted. Then we should think about what type of Finesse simulation we could run. Certainly one simulation is to look at the beam shape in the PRC, but more interesting could be how sensitive the shape is to mirror alignments. The current simulation shows a mode that resembles the TEM01, but I have not yet tried to find optimal alignment of the mirrors (in simulation) to search for the TEM00 mode.

 We've received all parts that we need for eddy current damping. I've made an estimate of Q with dirty tip-tilt. It looks fine (Q~1)

We need to check ring magnets for vacuum compatibility. Bob start baking on Friday.

[Jamie, Jenne, Raji, with consultation from Nic, Ayaka and Manasa]

We went back and re-looked at the input alignment, and now we're "satisfied for the moment" (quote from Jamie) with the PRC alignment.  Also, by adjusting the PR folding mirrors, we are almost perfectly aligned to the Yarm.

What we did:

Set PRM DC biases to 0 for both pitch and yaw.

Aperture was attached to PRM cage, double aperture was attached to BS cage, free-standing aperture was placed in front of PR2. 

Adjusted PZT1, PZT2 such that we were centered on PZT2, and through apertures at PRM and PR2.   This was mainly for setting beam height in PRC.

Checked centering on PZT1, MMT1, MMT2, PZT2.

Adjusted PRM pitch bias and PZT2 yaw such that REFL beam was retro-reflected from PRM.

Checked that REFL beam came nicely out of Faraday.

Checked that beam was still going through center of PRM aperture, and pitch height at PR2 was good.

Moved PR2 sideways until beam hit center in yaw of PR2.

Twisted PR2 such that beam was hitting center of PR3.

Moved and twisted PR3 (many times) so that beam went through BS input and output apertures, and through center of ITMY aperture.

Found that beam was just getting through black glass aperture at ETMY, top left corner, if looking at the face of ETM from ITM.

Locked down dog clamps on PR2.

This required some re-adjustment of PR3.  Re-did making sure going through BS apertures and ITMY aperture, locked down PR3 dog clamps.

Found that we are centered in yaw at ETMY, a little high in pitch on ETMY.

Replaced all of the light doors, to take a break.  4 hours in bunny suits seemed like enough that we earned a break.

This all sounds more straighforward than it was.  There was a lot of iteration, but we finally got to a state that we were relatively happy with.

What we will do:

Tweak PZT2 a *tiny* bit in pitch, ~0.5 mrad, so that the beam goes through the ETMY aperture.

See if we can align EMTY and ITMY to get multiple bounces through the Yarm.

Remove ETMX heavy door, steer BS such that we're getting through the center of an aperture at ETMX.

Align ETMX and ITMX such that we get multiple bounces through the Xarm.

Check SRM, AS path alignment.

Check REFL out of vac alignment.

Check other pickoffs.

Check all oplevs.

Check IPPOS/IPANG

We have a open-sided 2" mirror mount that we are considering using for the POY pick-off mirror.  This might help us get a little more clearance in the Y-arm of the Michelson.  Problem is the mount is not steerable, so we need to determine if that's doable or not.

[Raji, Jenne]

We tweaked PZT2, PZT1 (yaw only), and PR3 (pitch only) to get the beam ~centered on the BS aperture, the ITMY aperture, and the ETMY aperture.

After lunch I'll tweak up the MC alignment, since, although the spots are in the right places, the transmitted beam could be higher power.  This will make it easier to check our pointing, especially since the ETMY spot is larger than our aperture, but the beam is dim.

We're getting there!

 Jenne, Den

We looked at beam spots on ITMY and ETMY. We switched to smaller apertures on the other side of the rulers. For ITMY beam spot was 1mm below and 1mm south (right if you look in the direction ITMY -> ETMY) from the aperture center, for ETMY - 4 mm up and 3mm north from the aperture center. We made a correction for this using PZT 1 and 2. Now beam spots are in the middle of the apertures on ITMY and ETMY.

We tried to look at reflected beam from ETMY but it was hard to see the dependence between ETMY DC offset and reflected beam. We'll continue tomorrow.

 More data on the transmission. Measured the tranmission as a funtion of incidence angle at 1064nm

High particle count confirmed with #2 counter

jamie, nic, jenne, den, raji, manasa

We were doing pretty well with alignment, until I apparently fucked things up.

We were approaching the arm alignment on two fronts, looking for retro-reflection from both the ITMs and the ETMs.

Nic and Raji were looking for the reflected beam off of ETMY, at the ETMY chamber.  We put an AWG sine excitation into ETMY pitch and yaw.  Nic eventually found the reflected beam, and they adjusted ETMY for retro-reflection.

Meanwhile, Jenne and I adjusted ITMY to get the MICH Y arm beam retro-reflecting to BS.

Jenne and I then moved to the X arm.  We adjusted BS to center on ITMX, then we moved to ETMX to center the beam there.  We didn't both looking for the ETMX reflected beam.  We then went back to BS and adjusted ITMX to get the MICH X arm beam retro-reflected to the BS.

At this point we were fairly confident that we had the PRC, MICH, and X and Y arm alignment ok.

We then moved on the signal recycling cavity.  Having removed and reinstalled the SRC tip-tilts, and realigning everything else, they were not in the correct spot.  The beam was off-center in yaw on SR3, and the SR3 reflected beam was hitting low and to the right on SR2.  I went to loosen SR3 so that I could adjust it's position and yaw, and that when things went wrong.

Apparently I hit something BS table and completely lost the input pointing.  I was completely perplexed until I found that the PZT2 mount looked strange.  The upper adjustment screw appeared to have no range.  Looking closer I realized that we somehow lost the gimble ball between the screw and the mount.  Apparently I somehow hit PZT2 hard enough to separate from the mirror mount from the frame which caused the gimble ball to drop out.  The gimble ball probably got lost in a table hole, so we found a similar mount from which we stole a replacement ball.

However, after putting PZT2 back together things didn't come back to the right place.  We were somehow high going through PRM, so we couldn't retro-reflect from ITMY without completely clipping on the PRM/BS apertures.  wtf.

Jenne looked at some trends and we saw a big jump in the BS/PRM osems.  Clearly I must have hit the table/PZT2 pretty hard, enough to actually kick the table.  I'm completely perplexed how I could have hit it so hard and not really realized it.

Anyway, we stopped at this point, to keep me from punching a hole in the wall.  We will re-asses the situation in the morning.  Hopefully the BS table will have relaxed back to it's original position by then.

Here is a two hour set of second trends of 2 sensors per mirror, for BS, PRM, ITMY and MC1.  You can see about an hour ago there was a big change in the BS and PRM suspensions, but not in the ITMY and MC1 suspensions.  This corresponds as best we can tell with the time that Jamie was figuring out and then fixing PZT2's mount.  You can see that the table takes some time to relax back to it's original position.  Also, interestingly, after we put the doors on ~10 or 20 minutes ago, things change a little bit on all tables. This is a little disconcerting, although it's not a huge change.