JimW EricA Greg

This morning we disconnected the HEPI Actuators because the YAW correction needed by IAS was ~200urads or about .4mm at the HEPI foot.  The range of motion is only +-1mm, plus, the attached actuators will fight that amount of motion and cause non-expected responses.  Jason tweaked up the IAS gear and gave us the confirm on moving.  We brought it from 180urad CCW to 15urad CCW with 1/4 of a turn on each of the big Double Start Counter Wound (DSCW) HEPI Springs.  After lunch we set to reattaching the Actuators and while we'd like to see better centering of the Actuator Plates for max range of motion I think it will be plenty.  We'll have to really do driven range of motion measurements to determine this.
In the end based on the Dial Indicators relative the last In-Chamber Vertical survey of the optical table and post this mornings move and OK by IAS, HEPI has Yawed the Optic from 15urad ccw to 35urad cw (still in spec).  We also improved the level of the optical table, depending on how the tilting of the HEPI actually translates into the tilting of the optical table, from 0.5mm p-p to 0.3mm p-p.  So again all good; really we just got lucky.

I've attached a few pages from my logbook recording the in-chamber vertical survey and all the HEPI DSCW Spring adjustments and the Dial indicators readings.  Let me know if you want a guide or tour.

Brushing of BSC2 was completed and first vacuum started.

Unexpectedly, I found the ETMy undamped this morning and the loop switches in an inconsistent state of on or off.  I restored the switches to their appropriate on or off and enabled the damping on R0 and M0.  THe suspesnion should remained damped at all times.  It might, however trigger off a few times today as alignment activities commence.  I'll (or designee) try to keep it damped throughout the day.

At 06:28 local time Tuesday 22 May, h2fw0 crashed and restarted itself. Unfortunately the ini and par files had changed since the last DAQ restart and therefore h2fw0's frames contained bad data. The whole H2 DAQ was restarted at 8am to resync the whole system. A solution to the out-of-sync-configuration is being installed. The cause of the original crash is still under investigation.

The ring section and hand brushing of the upper chamber was completed yesterday. The flooring was shifted to one side and and half the chamber bottom was brushed.

Attached are plots of dust counts > .5 microns.

Over the past few days we've relocked the reference cavity in the optics lab, coupled the transmitted light into a fiber optic cable, and shot it down to End-Y.  This will be used to stabilize the ALS laser using a phase-locked loop, at least until the new H1 PSL has a serviceable FSS.

For the reference cavity, the setup is the same as that put in place by Matt, Bram, and Szymon last fall.  After a few days of loop tuning and optics tweaking (label your optics!  and for crying out loud, don't label something 'HWP' on one side and 'QWP' on the other!), we settled on a UGF of 120kHz with about 40 deg of phase margin.  The loop is pretty stable, but experiences an intermittent high-frequency oscillation that causes an audible buzzing in the EOM.  We're not sure what this is coming from, maybe insufficient gain in the fast path (relative to the fast-fast EOM path).  The visibility through the cavity is not great, only about 20% at the moment.

We take 95% of the transmitted light from the cavity and couple that into a fiber optic.  This coupling isn't that great either, only about 30%; the mode matching could use some work.  From there, the fiber runs to the mass storage room, and connects to a spigot of the communications cable that goes down the arm.  Four kilometers later it emerges in the VEA field rack, about ten meters from the ALS table.  We're using the first connector, in the upper left corner of the fiber patch panel.  The transmission from the optics lab down the arm is quite respectable, only about 5.7dB is lost.  Better than 1.5dB/km!

Here are some numbers:

41.6mW incident on the reference cavity
7.0 mW transmitted through the cavity
2.2 mW coupled into the fiber
0.6mW at End-Y

One potentially worrisome thing is that the fiber coupler appears to scatter light back into the reference cavity, which causes fringe wrapping or some other junk on the RFPD.  There's a bunch of noise in REFL_DC when the beam is aligned into the fiber coupler, and it goes away when you block the coupler with your hand.  We may have to install a Faraday isolator on the transmitted beam to keep this from polluting the PLL.

Another thing: does the reference cavity have some seismic isolation inside the vacuum can?  Like, is it sitting on springs?  When we hip-check the optics table there's a vertical mode at about 4Hz that gets rung up.

Currently for laser-safety reasons the fiber optic is disconnected in the optics lab, we'll plug it in once the cabling at the endstation is worked out.

Gerardo and I started the long process of leak testing new conflat joints on the H1 input MC volume.  Gerardo found a 6.1 x 10-7 torr*L/sec leak on HAM3 lower SW (1)12"x(3)4.5" feed-through (leak on 12" joint).  Much more hunting in the next few days.  

Also, I accidentally shut of the instrument air to the safety valve on the YBM MTP and had to restart the MTP shortly after it began to spin down.

The latest SUS ETMY measurements indicate the M0 & R0 masses are fully free-swinging with nearly all of the resonances lining up with the QUAD model.  The measurement from last night (05/21/12) is plotted with previous measurements of this QUAD with one from ITMY.  The drive in the 0.1-4Hz band was increased by a factor of three for all DoFs on both masses.  The result is a cleaner measurement in this band (compared to the 05/18/12 meas.) with a better SNR.   

D. Cook, J. Oberling

We set our equipment back up and measured pitch and yaw of the ETMy this afternoon.  The results are as follows:

• Pitch: 850 µrad down
  • Desired is 639 ± 160 µrad down, therefore this is out of spec
• Yaw: 220 µrad CCW
  • Desired is 0 ± 160 µrad, therefore this is out of spec

As can be seen by these results, further adjustment is necessary to bring the ETMy pointing into spec.

Been a while since there has been an alog about SEI assembly progress, so here goes...

Unit 5 is looking good at last report, after hunting down a couple of well hidden cable rubs (backside of an actuator and locker). Hugo could say better, but I'm tentatively hopeful we can put this assembly in the can next weekish. Unit 6 was floated for the first time today, and some rough adjustments were done to lockers and locker shims. This assembly looks rather a mess right now, partly because we are trying to match more recent wall payloads plans (less weight on the walls than previously thought) and partly because we are still missing things like actuators and walls, the last of the GS-13's for this assembly and some miscellaneous hardware that needs to be baked. As such, 6 will probably not be ready for testing for a couple weeks, so we are slowly nibbling away at prep work for LHO's 7th and final HAM. The optical table is mostly done with helicoils, Stage 0 is ready to be put on the assembly stand and we are putting together what sub-assemblies we can. We are still learning what hardware we've managed to misplace over the last ~2 years, so #7 may go a little slow.

BSC6 Activities

• Keita spent first part of morning investigating TMS mis-alignment (Hugh confirmed it was NOT ISI/HEPI-related). 
• VEA was then transitioned to LASER SAFE after his work. 
• Doug/Jason continued alignment work in the afternoon

Misc

• Dave rebooted h2DAQ just after 8am
• CP1 was filled via Praxair
• EY Dust Monitor alarmed for one cycle (100-200 counts).  After this alarm,noticed a "red box" around this dust monitor on the medm screen.  The box was red because there is a "calibrate failure".  Patrick said that if the status doesn't change, this dust monitor will need to be swapped out.

Awaiting a more detailed aLog but posting now to keep the masses up-to-date, I recently learned that the ETMy TFs from last night appear to show that it is free and clear of mechanical issues.  Doug and Jason are taking an IAS shot shortly.  I'm hoping they'll get assistance with damping if they need it (I'm tied up in the staging building).

TMS crew went into BSC6 to look at the viewports.  What was found was a significant misalignment in pitch, which is preventing the retro-reflection and HWS beams from making it through the table and out the viewport.

The two viewports on the South door look so much better, after the recleaning!

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Pictures:

First picture shows where the TMS beam is entering the vacuum system through the viewport.  This beam is misaligned on the TMS table in pitch, and diagnosis of the cause is ongoing today, so realignment/fixes will take place tomorrow.

Second picture shows a defect in the viewport, on the outside surface, that may be an issue for the Hartmann Sensor - will know more after TMS fixes.

The third picture shows the TMS beam close up, going through the viewport, and shows that there are point features, but no scratches or defects where the beam is going through the viewport, today.  The viewport looks good in this region, so I think it's unlikely that an issues will arise from alignment, which will move the beam on the viewport.

Fourth picture shows a feature of the viewport that's near the edge.  It might be helped with cleaning, but no threat to TMS/HWS beams, so not worth the risk to try to mitigate.

Pictures 5 is of the other viewport (BSC6 South Door, East Viewport).  There are a number of features that are visible, but already cleaned with freon, so likely in coating or a surface feature, and relatively small.

Picture number 6 shows a close up of the TMS beam on the inside surface of the viewport.  Point features are visible.

When we went to BSC6 to check the viewport for the ALS green beam, we've quickly found out that the beam was not hitting the EY, not even the primary.

The beam was at least 4mm too high on the secondary (picture will be posted by Cheryl). That's a huge number.

Since there's no lens/curved mirror between the ALS table and the secondary of the TMS telescope, and since the distance between the top periscope mirror of the ALS table and the secondary on the TMS telescope is something like 3.5m roughly, we're talking about 1mrad-ish number if it is something on the ALS table, and much much more if it is something on the TMS.

Vincent assured me that the ISI was good.

Hugh looked at the dial gauges of the HEPI and told me that the changes since May/07 are all 0.1mm or less. That's over 3 or 4mm distance. That's nothing compared to what we're seeing.

There was no change in the TMS bias voltages since we "finalized" the alignment a week ago, and though the OSEM values showed some drift it's about 1000 counts maximum, and that doesn't sound that big. Nobody worked on the ALS table since the last alignment. Picomotor driver cable was disconnected last time we finished working on that.

At this point, there are three potential cause of this:

1. Wedge of the viewport

BSC6 high quality viewport was removed from BSC6 for cleaning after our "final" TMS alignment, and then installed again.

Though this is "no-wedge" viewport, the spec (E1100267) says "up to 5 arc minutes", which is 1/12 degrees or 1.45 mrad. Assuming the refractive index of n=1.45 and using a small incident angle approximation, the angle deviation caused by this viewport is approximately up to

1.45 mrad * (n-1) = 0.65 mrad.

If the viewport was rotated 180 degrees after cleaning, that will cause up to 1.3 mrad difference.

Since the distance from the viewport to the secondary along the optical path is roughly 3m, 1.3 mrad roughly corresponds to 4mm shift.

2. Bias of the PZT mirror on the ALS table

We've found that one of the four inputs for the PZT mirrors is 14 Volt for whatever reason. I'm quite certain that the offset was there when we aligned the TMS. Indeed, when I disconnected the input cable from the PZT driver, the beam was totally misaligned and didn't even come out of the ALS table.

We still don't know why there's such a stupid offset, but anyway it's not impossible (though not very likely) that this offset drifted over time. The iris is much closer to the PZT mirrors than to the TMS secondary, so a tiny change in the PZT mirror angle could lead to a big position change on the secondary.

3. TMS mirrors

It's not impossible that the TMS mirrors got bumped. Again this is not very likely, because there are only two relevant mirrors  that are easy to bump, and it's kind of difficult to bump them to cause problem mostly in pitch only.

For the record--will report the current position of the HEPI relative to the position after we first installed the Actuators on May 3 & 4.  Likewise this is after latest OK from Initial Alignment before the Actuator install.

We see a tilt about the horizontal line running from SE to NW of less than 100urads & similar magnitude CW rotation about the vertical axis.

The largest absolute motions are +0.1mm vertical on the SE corner and 0.2mm south motion on the SE corner.  All other shifts are smaller and 3 of the 10 readings are zero.