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ID Date Author Type Category Subject
12178   Tue Jun 14 16:53:16 2016 ranaUpdateSUSETMX watch

12187   Thu Jun 16 11:10:17 2016 SteveUpdateSUSspare ETMX optics preparation to be hanged
 D Location Number on Drawing Component Name Baked Clean  Pieces Needed Pieces In Stock (on tower ) Notes 31,20,19,13 viton tips not cut yet baked material in stock 30 6-32x0.75" stops 4 (4) 29 steel music wire 0.017" not baked on roll needs good wipes 28 1/4 "washer 4 (4) 27 lock washer 4 50 install 26 Ag plated 1/4-20x1.25 4 (4) 25 Ag plated1/4-25x.75 & not plated 20 (20) 24 SS 4-40x.5 2 (2) 23 SS 4-40x.38 4 (4) 22 spring plunger 4+2 (4+2) 18 magnets, 1.9mm od, length 3.2 mm 5 ~30 not coated, rusty buy Ni coated ones for future use from www.electroenergy.com 17 guide rod, 0.635 mm od, 3.3 mm 3 6 Al 16 wire standoff, 1 mm od, 4.8 mm 2 2 Al and ruby (ruby groove not centered) 15 short OSEMs 5 6 14 spare ETMX in 40m wiki 1 1 confirmed in cabinet 12 dumbbell standoff 5 6 11 Al stiffening plate 1 (1) 10 wire clamp B in sus block 2 (2) 9 wire clamp A 1 (1) 8-7 lower clamp for lifting optics 2 (2) 6 upper clamp to hold down optic 1 (1) 5-4 left-right side of tower 1 ea (1ea) 3 tower base 1 (1) 2 sus block 1 (1) 1 lower and upper OSEM holders 1ea (1ea) 48 sandind fixture for magnet&dumbbell 45 magnet-dumbbell assemblly fixture 1 1 43 guide-wirestandoff gluing fixture 1 1 Ok for larger RUBY, unit is not in perfect condtition but usefull First contact 3-15-2013 purchase Pick up  FC from Gary with purchasing date 7-7-2015 or later FCPEEK peeler ring disk for TM cleaning 10 front,10 back side have sheets only 32&19mm ID punches ordered GordonBrush custom for LIGO optical cleaning ~5 1 (3/8wide nylonSS) more from Calum available EP30-2 epoxy have have expiration date 9-24-2016

NOT finished, last edited 7-7

Attachment 1: SOSsus_Page_1.png
Attachment 2: SOSsus_Page_2.png
Attachment 3: ETMXspareTowerFace.jpg
Attachment 4: ETMXspareTowerBack.jpg
Attachment 5: magnets-dumbbells.jpg
12199   Mon Jun 20 09:36:10 2016 SteveUpdateSUS EQ 3.1 m Big Bear Lake, CA

No suspention lost damping.

Attachment 1: eq3.1BigBearLakeCA.png
12218   Tue Jun 28 09:14:27 2016 SteveUpdateSUS ETMX optics preparation to be rehanged

Given the effect on the contrast defect, the consensus at the meeting Wednesday 6-22  was that we should continue to use the existing ETMX optic.

Does this imply that we can simply:
• Vent
• Remove the current ETMX suspension, and optic from the suspension
• Replace the standoffs (and guide rod if necessary), leaving the current magnets in place
• Re-suspend on the current, existing suspension, with new wire clamps
That is, if we are keeping the current optic, do we gain anything by replacing the whole suspension? Is there any reason to remove and replace magnets? (The wire clamps do need to be replaced, as a groove forms when they are installed.)

This could allow us to vent and execute this whole thing sooner.

-Eric Q.
...............................
Yes, I think this is a reasonable approach. Besides the wire standoffs and wireclamps, the only other problem might by a worn groove in the top piece of the suspension (not the clamp piece, but the piece that the clamp holds the wire up against).

How about use the current ETM, but put it into the new suspension body with new wire standoffs?

Quote:
 D Location Number on Drawing Component Name Baked Clean  Pieces Needed Pieces In Stock (on tower ) Notes 31,20,19,13 viton tips not cut yet baked material in stock 30 6-32x0.75" stops 4 (4) 29 steel music wire 0.017" not baked on roll needs good wipes 28 1/4 "washer 4 (4) 27 lock washer 4 50 install 26 Ag plated 1/4-20x1.25 4 (4) 25 Ag plated1/4-25x.75 & not plated 20 (20) 24 SS 4-40x.5 2 (2) 23 SS 4-40x.38 4 (4) 22 spring plunger 4+2 (4+2) 18 magnets, 1.9mm od, length 3.2 mm 5 ~30 not coated, rusty buy Ni coated ones for future use 17 guide rod, 0.635 mm od, 3.3 mm 3 6 Al 16 wire standoff, 1 mm od, 4.8 mm 2 2 Al and ruby (ruby groove not centered) 15 short OSEMs 5 6 14 spare ETMX in 40m wiki 1 1 confirmed in cabinet 12 dumbbell standoff 5 6 11 Al stiffening plate 1 (1) 10 wire clamp B in sus block 2 (2) 9 wire clamp A 1 (1) 8-7 lower clamp for lifting optics 2 (2) 6 upper clamp to hold down optic 1 (1) 5-4 left-right side of tower 1 ea (1ea) 3 tower base 1 (1) 2 sus block 1 (1) 1 lower and upper OSEM holders 1ea (1ea) 48 sandind fixture for magnet&dumbbell 45 magnet-dumbbell assemblly fixture 1 1 43 guide rod gluing fixture shipped from LOH .... D000335...needs cleaning First contact 3-15-2013 purchase check expiration date OK FCPEEK peeler ring disk for TM cleaning 10 front,10 back side have sheets only 32&19mm ID punches ordered GordonBrush custom for LIGO optical cleaning ~5 1 (3/8wide nylonSS) more from Calum available EP30-2 epoxy have have expiration date 9-24-2016

NOT finished, last edited 6-28

Attachment 1: nylonFCss.jpg
12226   Wed Jun 29 08:20:04 2016 SteveUpdateSUS First Contact shelf life
We'll follow LIGO policy:
Our policy is to use first contact within 1 year of purchase for use in the interferometers.  For inspection use I am comfortable with out-of-date use.


GaryLinn offered their indate First Contact for use.

12227   Wed Jun 29 14:32:22 2016 SteveUpdateSUS how to remove epoxy from optics

Hi Steve -

I found the doc I was looking for:

https://dcc.ligo.org/LIGO-E1200821

Specifically, you might find guidance in Section 5 and the pictures at the end of the doc.  This should work for Vacseal as well.

Good luck - it will take some time (hours to day or 2)...
I'll be interested to know how it goes.

GariLynn helped us develop this procedure so you could also ask her to cast an eye over the setup if you are worried.

-Betsy

ps: there is no existing fixture to hold SOS optic while soaking it

12229   Wed Jun 29 16:02:29 2016 SteveUpdateSUS ETMX beam baffle

In the attached photo from 2012, one can see the installed black glass baffle. According to the drawings (LIGO-DNNNXXX) this one has a clear aperture of 40 mm.

In (someplace ?) we have clean baffles with a 50 mm aperture which can be installed during this vent. In order to be more conservative, let us choose to swap these out for all 4 test masses during the upcoming vent using the green laser as an alignment guide, as Koji described at today's lunch meeting.

They are located at the top of E1 drawer cabinet

Attachment 1: IMG_1608.JPG

I've gone through the SOS suspension document (E970037) and some old elogs to get an idea of all the accesories we need for the process of suspending, aside from the tower itself, which Steve has already put together. Gautam and I have laid our eyes upon most of the critical pieces. Some other objects are unknown, and perhaps not strictly neccesary.

Confirmed to exist:

• Guide rod gluing fixture
• 3 axis micrometer + microscope doohicky
• PZT buzzer (for fine standoff positioning)
• Winch fixture (the plate maybe doesn't fit perfectly on the top of the SOS tower, but one bolt will probably work)
• Spare guide rods and ruby standoffs
• Magnet+dumbell gluing fixture (in case we need to glue a new magnet+dumbell pair)
• Magnet to optic gluing fixture (including "pickle pickers"/grippers)
• 0.017" suspension wire
• HeNe laser + QPD + beam height target (confirmed working on scope)

In addition, I am told that we have a long ribbon cable that can run from the X end to the clean room to enable OSEM damping control while we do the pitch alignment.

• Something called an "SOS set screw tool" (D961412)
• Not mentioned specifically what this is for
• Edmund scientific pocket measuring microscope + bushing
• Seems to be intended for centering OSEM holding plate on the magnet position. I found no mention of this use in 40m elogs. It can likely be done by eye
• SOS cleaning bracket (D970181)
• This is likely for the old liquinox cleaning procedure. We'll be using first contact.

Some other tasks and their status:

• Check cleanroom table levelling:
• Done via 12" spirit level, looks good
• Glue removal strategy / fixture
• Steve is working on this
• Cut and apply viton tips to earthquake stops
• Either gautam will do this, or we will use the current suspension's stops
12231   Thu Jun 30 10:03:16 2016 SteveUpdateSUS how to remove epoxy from optics

Proposed Acetone soak dish for SOS epoxy softening.

It has good acces through 5" top ID. The set up is stable and teflon lined.

Materials: glass jar with SS cover, teflon bricks, 0.008" teflon wrapped "high density Drever bricks" and aluminum

Drever brick: I beleive it is a Tungsten alloy. We used it as vac-bat savor at the coffe can. It has high density, heavy and hard, it was never identified.

I will soak one brick  to see if it has any reaction ability with acetone.

NO means that only Glass and Teflon can be used for this fixture in  Acetone. We can not take a chance on the coating!

I guess the small surface area Aluminum dumbbell, guide rod and-or wire standoff, magnet and epoxy does not degrade the acetone such way that it effects our coating.

Not ot mention, that only the very edge of the coating would in this solution.

Attachment 1: SOSsoakDish.jpg
Attachment 2: SOSsoakDish_tv.jpg
12232   Thu Jun 30 14:31:02 2016 ChemistryUpdateSUSNO

12241   Tue Jul 5 09:25:31 2016 SteveUpdateSUS how to remove epoxy from optics

Glass soaking dish with teflon guides.

 Quote: Proposed Acetone soak dish for SOS epoxy softening. It has good acces through 5" top ID. The set up is stable and teflon lined. Materials: glass jar with SS cover, teflon bricks, 0.008" teflon wrapped "high density Drever bricks" and aluminum Drever brick: I beleive it is a Tungsten alloy. We used it as vac-bat savor at the coffe can. It has high density, heavy and hard, it was never identified. I will soak one brick  to see if it has any reaction ability with acetone.   NO means that only Glass and Teflon can be used for this fixture in  Acetone. We can not take a chance on the coating! I guess the small surface area Aluminum dumbbell, guide rod and-or wire standoff, magnet and epoxy does not degrade the acetone such way that it effects our coating. Not ot mention, that only the very edge of the coating would in this solution.

Attachment 1: SOSsoakingDish.jpg
Attachment 2: SOSsoakingD.jpg
12264   Thu Jul 7 09:13:54 2016 SteveUpdateSUSSOS gluing fixture

Atm 1, It's right arm is perfect.

Atm 3-4, The left one has bended (dropped) end.

Atm 2, Our ruby wire stanoffs will fit the jig. Ruby OD 1.27 mm vs. old Aluminum OD 1.0 mm. Length ruby 6.4 mm vs Al 4.8 mm

Atm 5, The fixture translation stages are a bit loooose. Careful use of the micrometer is needed to be precise

Betsy agreed that the 40m will keep SOS fixtures.

Attachment 1: SOSgluingFixRarmWend.jpg
Attachment 2: SOSgluingFixRarm.jpg
Attachment 3: SOSgluingFixLarm45.jpg
Attachment 4: SOSgluingFixLarm.jpg
Attachment 5: SOSgluingFixture.jpg
12315   Wed Jul 20 13:58:55 2016 SteveUpdateSUSSUS damping out of vac chamber

Cheater cable to be used in clean room pitch gluing alingment.

Satelite amp needs to be there.

Atm 2-3, The ETMs  suspension damping cable  are connected at the end racks. All others go to 1X5

Atm 4-5, The other end of this cable in the high cable tray at 1X3 as shown. We'll disconnect the shorty and move the end to ETMX ( or any sus at 1X5 )

Attachment 1: ETMXrack.jpg
Attachment 2: fromETMX-satBox.jpg
Attachment 3: susDampingSatboxCab.jpg
Attachment 4: susDampingSatboxCabl.jpg
12316   Wed Jul 20 14:03:01 2016 ericqUpdateSUSEffect of thicker ruby standoffs

The new ETMX ruby guide rods are slightly thicker than the old aluminum ones; specifically 1.27mm vs 1.0mm.

Since we did not change the guide rod location in response to this fact, the vertical position of the suspension point changes, which in turn changes the dynamics of the suspension. Specifically, since the standoff is placed below the guide rod, the suspension point is lowered, which makes the pitch mode softer. I crunched a few numbers and have determined that this effect should not be a problem.

Given the wiki's value of the ETMX pitch resonance frequency of 0.829 Hz, I predict a the new pitch resonance frequency of 0.800 Hz.

A useful document about the dynamics of our suspension can be found at T000134

From this document, one will find that the effect of changing the suspension point height over the optic center of mass,b, on the pitch resonance frequency (while keeping all other dimensions equal) to be:

$\frac{\omega'_\theta}{\omega_\theta} \approx \sqrt{\frac{b'}{b}}$

The top of the standoff is fixed by the guide rod, so let's say that b' is given by the position of the center of the Ruby standoff. This is then smaller than the previous b by the differences in the radii of the standoffs:

$b' = b - \frac{\oslash_{\textrm{ruby}}-\oslash_{\textrm{Al}}}{2}$

The nominal value of b is 0.985mm. Thus, the pitch resonance frequency is changed by factor of 0.965, i.e. 3.5% smaller. Then, taking the wiki value of 0.829 Hz results in 0.800Hz, a 30mHz decrease.

12334   Mon Jul 25 17:01:54 2016 SteveUpdateSUSETMX suspension - progress

ITMY side  : Magnet od 1.9 mm so wire to magnet gap ~ 0.2-0.3 mm

Attachment 1: ITMYside2011.JPG
12341   Wed Jul 27 11:40:48 2016 steveSummarySUSoplev laser summary updated

Quote:

Quote:

Quote:

 Quote: 2005              ALL oplev servos use Coherent DIODE LASERS # 31-0425-000, 670 nm, 1 mW     Sep. 28, 2006              optical lever noise budget with DC readout in 40m,  LIGO- T060234-00-R, Reinecke & Rana     May  22, 2007              BS, SRM & PRM  He Ne 1103P takes over from diode     May  29, 2007              low RIN He Ne JDSU 1103P selected, 5 purchased sn: T8078254, T8078256, T8078257, T8078258 & T8077178 in Sep. 2007     Nov  30, 2007               Uniphase 1103P divergence measured     Nov. 30, 2007               ETMX old Uniphase 1103P  from 2002 dies: .............., running time not known......~3-5 years?     May 19, 2008               ETMY old Uniphase 1103P from 1999 dies;.....................running time not known.....~    ?     Oct.  2, 2008                ITMX & ITMY are still diodes, meaning others are converted to 1103P earlier                        JDSU 1103P were replaced as follows:    May 11, 2011                ETMX replaced, life time 1,258 days  or 3.4 years    May 13, 2014               ETMX , LT 1,098 days or 3 y    May 22, 2012               ETMY,  LT 1,464 days or  4 y    Oct.  5, 2011                BS & PRM, LT 4 years,  laser in place at 1,037 days or 2.8 y    Sep. 13, 2011               ITMY  old 1103P &    SRM    diode laser replaced by 1125P  ..........old He life time is not known, 1125P in place 1,059 days or 2.9 y    June 26, 2013              ITMX 622 days or 1.7 y    note: we changed because of beam quality.........................laser in place 420 days or 1.2 y     Sep. 27, 2013               purchased 3 JDSU 1103P lasers, sn: P893516, P893518, P893519 ......2 spares ( also 2 spares of 1125P of 5 mW & larger body )

May  13, 2014             ETMX,  .............laser in place 90 d

May  22, 2012             ETMY,

Oct.  7,  2013             ETMY,  LT  503 d  or  1.4 y............bad beam quality ?

Aug. 8,  2014              ETMY,  .............laser in place   425 days  or  1.2 y

Sept. 5, 2014              new 1103P, sn P893516  installed at SP table for aLIGO oplev use qualification

May 23, 2016             ITMX dead laser sn P845648 replaced after 1062 days [2.9 yrs] by 1103P, sn P859884, with output output  2.6 mW, nicely round beam quality at 15 meters.

July 27, 2016             2  new 1103P from Edmonds in: P947034 & P947039, manf. date April 2016,

12342   Wed Jul 27 15:03:02 2016 sisyphusMetaphysicsSUSBroken wire

While tightening the bolts on the ETMX wire clamp, the wire broke. All four face magnets broke off.

Fortunately, no pieces were lost.

12343   Wed Jul 27 16:56:47 2016 ranaMetaphysicsSUSBroken wire

For the rest of this vent, at least, we need to start using the EQ stops more frequently. Whenever the suspension is being worked on clamp the optic. When you need it to be free back off the stops, but only by a few hundred microns - never more than a millimeter.

Best to take our time and use the stops often. With all the magnets being broken off, its not clear now how many partially cracked glue joints we have on dumbells which didn't completely fall off.

12346   Thu Jul 28 08:42:36 2016 SteveUpdateSUS wire clamp

The clamp is in the machine for milling off the grooves. It's condition is normal. The edges needs some 800 sand paper so it is not sharp anywhere.

How did those nicks get on the edge? Fortunatelly they did not aligned with the wire.

Attachment 1: e12342.jpg
12353   Fri Jul 29 03:59:55 2016 ericqUpdateSUSIn air OSEM diagonalization check

The question arose whether we can get good enough data to diagonize our OSEM sensing matrices in air.

I just took a look at the BS spectra over the last six hours (~10PM-4AM), and the SNR looks good. The BS diagonalization itself doesn't seem so great; the POS is hugely coupled into pitch and yaw, and the angular motions are themselves coupled to each other at around 10%.

NB: use a flat-top window when you really care about peak heights that don't fall exactly on an FFT bin.

I would've liked to check this for the PRM and SRM too, but one of the PRM sensors continues to be dark, and I just noticed that all of the SRM OSEM signals are dark. ughhhh

Attachment 1: BS_OSEM_diag.pdf
12355   Fri Jul 29 15:17:23 2016 SteveUpdateSUSwire and clamping test

Unbaked steel music wire from  "Ca Fine Wire Co" from 24" od spool, od 0.0017" used. Identical to the one that broke.

The set up as shown with silver plated screws-washers on clamp. The unused clamp edges were sanded on P800 paper at 45 degrees just not to be very sharp.

Use your finger to feel the sharpness of  edge and sand till it gets a little bit not so sharp. The drawing note is "sharp edges" on wire clamp for low loss, high Q in mind.

The wire broke at the midle with single load 295 grms

The wire hold on overnight at single load 242 grms  Vezo torque wrench is not accurate!  This test was performed ~ 1.5Nm  DO NOT USE THIS NUMBER! (added at 8-10-2016)

This gives us a factor of 2 safety  with loop suspended of 250 grms small optic.

Attachment 1: 43micr242grs.jpg
12357   Fri Jul 29 20:12:54 2016 gautamUpdateSUSthird time - no luck

[lydia, gautam]

Summary: Third unsuccessful attempt at getting ETMX suspended. I think we should dial the torque wrench back down to 1.0 N m from 1.5 N m for tightening the primary clamp at the top of the SOS tower. No damage to magnets, standoff successfully retrieved (it is sitting in the steel bowl)

Details:

• We burned through two sets of wires today.
• First, the assembly Eric and I had put together last night failed when Eric tightened the wire clamp (no torque wrench was used I think?)
• This afternoon, Lydia and I re-assembled the suspension once again. Standoff was successfully inserted, coarse pitch balancing was achieved relatively easily - we think that the coarse pitch balance can be achieved if the end of the wire standoff closer to the groove is ~0.5mm ahead (i.e. towards HR side) of the guide rod.
• Checked leveling of scribe lines, gave an extra 0.25 turns on the winches in anticipation of the wire sagging
• Inserted OSEMs just short of magnets, verified that they were approximately centered, if anything, slightly above center, again in anticipation of the wire sagging.
• After taking pictures, we went ahead and attempted to clamp the wire (ALL EARTHQUAKE STOPS WERE ENGAGED)
• Eric commented that the clamp piece did not slide in smoothly on the dowels (indeed it does not come off very easily either, I have just left it on for now). I don't remeber it being so difficult prior to us sending it into the maching shop to get rid of the grooves made by the suspension wire the first time around. But with the torque wrench, the piece moved in relatively easily (we had sanded down rough edges prior to putting this piece onto the suspension earlier in the afternoon.
• I could feel that the torque wrench coming up on its limit. But the wire snapped before the torque wrench clicked. As far as I am aware, there were no rough edges on the piece, but perhaps we missed a spot?
• I took the opportunity to discharge the optic using ionized nitrogen at 40psi. After about 2-3 minutes of a steady stream, I verified that a piece of the suspension wire no longer gets attracted to the barrel, as was the case earlier today.

Unfortunately I don't know of a more deterministic way of deciding on a "safe" torque with which to tighten the bolts except by trial and error. It is also possible that the clamping piece is damaged in some way and is responsible for these breakages, but short of getting the edges chamfered, I am not sure what will help in this regard.

Unrelated to this work: earlier today before the first wire failure, while I was optimistic about doing fine pitch balancing and gluing the standoff, I set up an optical lever arm ~3m in length, with the beam from the HeNe on the clean bench at 5.5 in above the table, and parallel to it (verified using Iris close to the HeNe and at the end of the lever arm). I also set up the PZT buzzer - it needs a function generator as well for our application, so I brought one into the cleanroom from the lab, isopropanol wiped it. The procedure says apply 5Vrms triangular wave at 1000Hz, but our SR function generators can't put out such a large signal, the most they could manage was ~2Vrms (we have to be careful about applying an offset as well so as to not send any negative voltages to the PZT voltage unit's "External input". All the pieces we need for the fine pitch balancing should be in the cleanroom now.

12359   Mon Aug 1 14:09:20 2016 SteveUpdateSUSthird time - no luck

Gautam and Steve,

The clamp's left side was jammed onto the left guide pin. It was installed slit facing left. Gautam had to use force to remove it. The clamp should move freely seating on the guide rods till torque aplied. Do not move on with the hanging of optic with a jammed clamp. Fix it.

Never use force as you are hanging - aligning optic. The clamp is in the shop for resurfacing and slit opening.

12362   Wed Aug 3 00:15:39 2016 gautamUpdateSUSETMX suspended

[lydia, steve, ericq, gautam]

Summary:

• ETMX is now suspended by wire clamps (winches have been removed)
• Wire clamp was machined by shop, D groove widened to spec, old wire grooves removed from face
• We also sanded the part of the suspension tower in contact with the primary wire clamp, as there were a couple of craters there which looked dangerous (pictures to follow)
• Height was adjusted by centering magnets on OSEMs. We then winched an extra half turn in anticipation of wire sag
• I then proceeded to tighten, first, the primary wire standoff (I reduced the torque on the torque wrench to ~1.25Nm), and then the secondary wire clamps.
• Checked that the ruby standoff is sitting on the optic barrel and not on glue
• Later in the evening, I inserted OSEMs, centered magnets, and checked that the damping scheme set up last week works (I'm leaving the damping on, bottom EQ stops are ~0.5mm from the optic)
• Checked the pitch balancing - initially, we were ~60mrad off. By using the tweezers to gently adjust the position of the ruby standoff (after clamping the optic, turning the damping off), I was able to improve the situation a little bit - now we are ~20 mrad off. I am not attempting to do the fine pitch balancing tonight, but all parts of the PZT buzzer set up are ready to go in the cleanroom.
• Unfortunately, in the process of doing the pitch balancing, the position of the magnets relative to the OSEM coils have moved. Now the UR magnet looks a little high relative to the coil, but perhaps after any sag has set in, we should be alright. Else, we can probably get away by inserting one of the little metal shim pieces, the adjustment required is small.
• Lydia will upload some photos soon.
• We actually went through another failed attempt today - this time, the problem was that the winches were not sufficiently secure at the top, such that when the range of the winch was nearing its end, the whole assembly twisted and took the wire along with it. Perhaps this would not have happened if we had a winch adaptor plate handy...
• Plan for tomorrow:
• ​Fine pitch balancing using PZT buzzer
• Clean ETMY epoxy residue from knocked off magnet
• Glue wire standoff
• Glue ETMY magnet
12363   Wed Aug 3 09:26:54 2016 LydiaUpdateSUSETMX suspended: photos

Here are the photos we took showing the magnet positions in the OSEMs, and others showing the positions of the wire and unglued standoff. These were taken before the pitch balancing adjustment Gautam described, which apparently cause UR to be a little too high. Thoe OSEMs were all inserted only until the ends of the magnets were almost inside, to lower the risk of knocking any magnets off.

At the time of these pictures, all magnets except LL were intentionally positioned slightly above the center of the OSEM in anticipation of wire sag. The LL magnet was approximately centered in the OSEM. It was not possible to get both LL and UL the same height relative to their respective OSEMs, possibly due to a spacing error when they were glued to the optic.

Attachment 1: Position of wire along bottom of the optic. Looks adequately centered and not kinked.

Attachment 2: Photo showing good contact between the sandoff and the barrel of the optic. The standoff does not appear to be resting on glue from the guiderod.

Attachment 3: Shows position of standoff and wire after rough pitch banacing. Wire is visibly resting in the groove.

Attachment 4: SD magnet location photographed through OSEM.

Attachment 5: LL magnet location photographed through OSEM.

Attachment 6: LR magnet location photographed through OSEM.

Attachment 7: UL magnet location photographed through OSEM.

Attachment 8: UR magnet location photographed through OSEM.

Attachment 1: wire_bottom.JPG
Attachment 2: standoff_contact.JPG
Attachment 3: wire_in_groove.JPG
Attachment 4: SD.JPG
Attachment 5: LL.JPG
Attachment 6: LR.JPG
Attachment 7: UL.JPG
Attachment 8: UR.JPG
12367   Wed Aug 3 15:36:57 2016 SteveUpdateSUSNi plated magnets & epoxy ordered

Ni plated SmCo magnets with specification of LIGO-C1103521-v2 for SOS ordered from Electron Energy Corp

100 pieces of Ni- Platted magnets are in 9-27-2016 They are stored at clean cabinet S15

EP30-2 epoxy  1/2 pt kit 250 ml of part A and 25 ml of part B should be here in 7 days. These can packed epoxy is much more economical than the double barrel cartridges.

Spare SOS wire clamps will be out of the machine shop next week.

12370   Thu Aug 4 03:14:39 2016 gautamUpdateSUSETMX suspended
 Quote: [lydia, steve, ericq, gautam] Summary: ETMX is now suspended by wire clamps (winches have been removed)  Unfortunately, in the process of doing the pitch balancing, the position of the magnets relative to the OSEM coils have moved. Now the UR magnet looks a little high relative to the coil, but perhaps after any sag has set in, we should be alright. Else, we can probably get away by inserting one of the little metal shim pieces, the adjustment required is small

[lydia, ericq, gautam]

• Turns out setting the height of the optic with the OSEMs isn't quite reliable. We were indeed too high, for all the OSEMs
• Related to the above - we observed no sag (which is one of the reasons we winched a little bit extra in the first place)
• Eric and I re-did the suspension in the afternoon. We found no wire grooves in the primary (or secondary) clamps, so we just reused them (is this a red flag? should we be using more torque?)
• This time we set the height using the traveling microscope - double checked the height to which the microscope was levelled = 5.5"
• Having checked the height of both scribe lines, we proceeded to clamp the suspension, with ~1.35Nm of torque (since 1.25Nm seemed a little low, no wire grooves were made in the clamps) - clamping was successful
• In the evening, Lydia and I attempted to do the fine pitch balancing
• Both left side magnets (as viewed from the AR side) are low (within 0.5mm of the teflon). Right side magnets are pretty well centered. But left side ones seemed usable so we went ahead and tried to turn the damping on.
• Damping worked reasonably well
• Tried to do fine pitch balancing with PZT buzzer. Reduced voltage from Fn generator to 0.4Vrms (down from 1.7Vrms) but had limited success.
• I was able to do much better with just the teflon tipped tweezers. So gave up on the PZT buzzer
• After ~3hours of a random walk between two pretty-close-to-ideal positions, we have now realized a fine pitch balancing of ~1mrad (~3mm off the ideal height of 5.5" over a lever arm of ~1.5m, but the mirror tilt is half of this angle)
• Actually, I was able to do much better - at one point, we even had the reflected beam dead center on the iris 1.5m away. But adjusting the OSEM positions even a little bit (say from oscillating around 40% to 50% of the maximum value) has a BIG effect on the pitch balance (it caused a misalignment of 4mrad)
• I think gluing the standoff without destroying the fine pitch balancing is going to be very challenging, judging by how gently I had to touch the standoff to destroy the fine pitch balance completely. Perhaps we want to consider using some 3 axis stage to bring the needle with glue in and perturb the standoff as little as possible

Lydia also briefly played around with the IR camera to inspect the OSEMs. A more thorough investigation will be done once the cage is in for air baking. From our initial survey, we feel that the beams are pretty well aligned along the straight line between PD and LED - we estimate the upper bound on any misalignment to be ~10 degrees.

12377   Fri Aug 5 02:17:10 2016 gautamUpdateSUSETMX Ruby Wire Standoff Ready for Gluing

Part 1: Rotation of optic

• As reported in my elog yesterday, both the left magnets (UL and LL) seemed too low relative to the OSEM coils
• Eric and I checked the height of the scribe lines using the microscope and found that the scribe lines were low on the left side and high on the right side (as viewed from the AR side) by approximately the same amount, confirming our suspicion that the optic was rotated. The position of the scribe line on the bottom of the optic relative to the bottom-rear face EQ stop also suggested the same
• Eric brought in the bottom EQ stops, and once the wire was slightly unloaded, rotated the optic by the required amount by hand
• This process took two tries, but we were successful
• Re-checked heights of scribe lines using microscope, and once we were satisfied, re-did the coarse pitch balancing

Part 2: Replacement of holder for top pair of OSEMs

• Eric and I had difficulty removing the UR OSEM-holding screw
• This is the non-silver-coated new variety of screw
• It got to a point where I could neither move the screw in or out, even with the help of a pair of pliers
• I decided to swap out the piece of the suspension tower holding the top two OSEMs (UR and UL) with the same piece from the old ETMX tower that is currently residing on the flow bench at the south end (along with the accompanying piece that overhangs the optic and holds the front-face and top earthquake stops
• I cleaned the piece 3-4 times with acetone, and then a couple of times with isopropanol. I adjudged this to be sufficient as we are going to air bake the tower anyways prior to installation in the vacuum chamber
• I then swapped the pieces:
• First I brought in the bottom pairs of EQ stops
• Next, I secured the optic using the three lower face EQ stops
• Then, I removed the EQ stop screws from the overhanging piece, after which I removed the overhanging piece itself
• After removing the top-back EQ stop, I removed the OSEM-holding piece from the suspension tower
• Did the above steps in reverse, installing the new piece
• All went smoothly. This piece does not have a serial number unfortunately
• After this, I re-inserted the OSEMs, and judged the magnet-coil alignment to be satisfactory to proceed further
• We decided to use the old variety of silver plated OSEM holding screws for the top two OSEMs (by choice) and the side OSEM (the new variety is too short anyways). During the course of my work tonight, I found this worked way better. The bottom pair of OSEMs remain held by the new variety of unplated screws. We may want to review whether we really want to use this new type of screws (I believe the idea is to make it easier to tighten and loosen the screws)

Part 3: Fine pitch balancing

• As per the SOS assembly procedure, I turned off the HEPA filters at the clean bench for this part of the work
• Checked that the HeNe beam incident on the optic was level with the tabletop, beam height set to 5.5"
• Proceeded to do the fine pitch balancing the same way as described in yesterday's elog (i.e. no PZT buzzer, just fine touches by hand)
• I was able to converge fairly quickly to a good point in configuration space
• After re-centering the OSEM coils such that the PD output was ~50% of its maximum value (see Attachment #1), I found over a lever arm length of 56" (=1.42m) a beam height deviation from 5.5" by <2mm. This corresponds to 0.7mrad pitching forwards towards the HR side
• The suspension assembly procedure tells us to aim for 0.5mrad, but I think this is close enough for standoff gluing, as this misalignment is extremely sensitive to the OSEM coil positions (although I would say, from Attachment #1, that they are actually pretty well centered)
• The only thing that concerns me is that the LL magnet is still a little low relative to the coil. This can be fixed by shimming if necessary...

Attachment #1: Striptool trace showing OSEMs are pretty well centered (towards the end, I turned on the HEPA filters again, which explains the shift of the traces). The y-axis is normalized such that the maximum displayed corresponds to the fully open PD output of the coils

Attachment #2: Fine pitch balancing optical lever setup

Attachment #3: Tower assembly

Attachment #4: SIDE OSEM close-up

Attachment #5: UR OSEM close-up

Attachment #6: UL OSEM close-up

Attachment #7: LL OSEM close-up (this is the concerning one)

Attachment #8: LR OSEM close-up

We should also check the following (I forgot and don't want to wear my clean jumpsuit again now to take more photos):

1. Wire is still in groove
2. Standoff is sitting on the optic barrel and not on epoxy residue of the guiderod
Attachment 1: OSEMs.PDF
Attachment 2: IMG_2932.JPG
Attachment 3: IMG_2934.JPG
Attachment 4: IMG_2935.JPG
Attachment 5: IMG_2936.JPG
Attachment 6: IMG_2937.JPG
Attachment 7: IMG_2938.JPG
Attachment 8: IMG_2939.JPG
12378   Fri Aug 5 04:43:09 2016 KojiUpdateSUSETMX Ruby Wire Standoff Ready for Gluing

If only the LL magnet looks too low, doesn't this mean that the OSEMs are not arranged in a square shape?
If so, you can fix this misalignment by moving the OSEM holding plate rather than OSEM shimming, can't you?

12379   Fri Aug 5 09:38:12 2016 SteveUpdateSUSSOS sus wire ordered

0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will be on 8" OD. spool too.

Attachment 1: 0.0017.jpg
Attachment 2: 0.0017spec.jpg
12381   Fri Aug 5 18:21:28 2016 gautamUpdateSUSETMX Ruby Wire Standoff GLUED
• The latest twist in this apparently never-ending saga was that even though fine pitch balancing was achieved, the wire was out of the groove on both sides!
• I rectified this situation in the morning, did the fine pitch balancing in the afternoon
• Koji's suggestion of adjusting the OSEM holding plate totally did the trick, all four magnets are reasonably well centered relative to the vertical now...
• After the latest round of fine pitch balancing, we are now tilted in pitch backwards (i.e. towards the AR face) by <0.7mrad.
• Prior to gluing, I visually inspected the optic to check that (see attachments):
• Wires are in grooves on both sides
• Unglued ruby standoff has the correct "rotation", i.e. that the wire contacts the standoff after the groove has started, and leaves it before the groove ends, since the groove doesn't go all the way around the standoff
• Section of wire around the bottom half of the optic has no obvious kinks/other funny features
• Unglued standoff is in contact with the barrel
• All magnets are well clear of teflon in OSEM coils on both sides
• Eric also checked the frequencies of the various modes (PIT, YAW, POS and SIDE) by looking at the power spectrum of the free-swinging error signals on the coils. The pitch mode is now softer than before, at ~710mHz
• We then proceeded to glue the optic, using a needle to apply the glue (optic was clamped using face EQ stops, bottom EQ stops were not engaged as we felt this would affect the fine pitch balancing
• During the process, it looks like we may have inadvertently gotten some glue onto the wire (see attachments) - it doesn't look like any has seeped into the groove itself, but there is definitely some on the wire. We can possibly try cleaning this once the optic is out. In the worst case scenario, we will have to loop another section of wire, but the fine pitch balancing should be unaffected provided we did not perturb the optic too much
• Bob has said the large oven will be available to bake the cages on Tuesday, August 9th. By this time, we should have ETMY suspended as well (we were unable to glue the knocked off magnet on ETMY as the glass bowl we had for soaking the edge of the optic in acetone to remove the epoxy residue broke while I was assembling the various pieces of Teflon inside it. Steve is procuring a new one on Monday). It is still unclear when we can vacuum bake the two ETMs...

Attachments:

Attachment #1: Wire is in the groove in the unglued wire-standoff, groove rotation looks pretty good.

Attachment #2: Ruby standoff is sitting on the barrel of the optic (if you zoom in)

Attachment #3: Side magnet is well centered w.r.t OSEM coil

Attachment #4: UR magnet is well centered w.r.t OSEM coil

Attachment #5: UL magnet is well centered w.r.t OSEM coil

Attachment #6: LL magnet is well centered w.r.t OSEM coil

Attachment #7: LR magnet is well centered w.r.t OSEM coil

Attachment #8: Wire is in the groove in the glued Ruby standoff

Attachment #9: Standoff after gluing. 3-4 drops of epoxy are visible on the wire, but none looks to have seeped into the groove itself

Attachment #10: Side view of newly glued Ruby standoff

Attachment #11: Before and After gluing shots.

Attachment 1: IMG_2966.JPG
Attachment 2: IMG_2969.JPG
Attachment 3: IMG_2970.JPG
Attachment 4: IMG_2972.JPG
Attachment 5: IMG_2972.JPG
Attachment 6: IMG_2973.JPG
Attachment 7: IMG_2974.JPG
Attachment 8: IMG_2967.JPG
Attachment 9: IMG_2980.JPG
Attachment 10: IMG_2985.JPG
Attachment 11: BeforeNAfter.PDF
12382   Sun Aug 7 14:53:39 2016 ericq UpdateSUSETMX Standoff gluing was successful

I came in to check on ETMX. I freed the earthquake stops, and found that the OSEMS were reasonably, but not perfectly, centered. Turning on the damping, I found that the pitch balance is biased slightly downwards at about ~0.5mrad, which is acceptable.

As another check for how much we moved the standoff while gluing, we can look at the spectra of the OSEMS while the mirror is free swinging, and see if/how the resonance frequencies have moved around. As Gautam previously mentioned, the pitch frequency is even softer than we expected from the thicker ruby standoff alone. This is due to the excess glue around the guide rod forcing us to position the standoff even lower to have good contact with the optic's barrel. In the plot below, the design yaw/pit/pos frequencies are the dashed lines, and the measured frequencies are the solid lines.

[The plot is not in spectral density units, so that the peak heights reflect real units of motion at each resonance frequency. Data and code used to generate the plot is attached]

 Yaw Pitch Pos Side Design frequencies from T000134: 0.773 Hz 0.856 Hz 1.001 Hz ETMX Measurement in-air 2010 0.828 Hz 1.04 Hz 0.908 Hz 0.949 Hz Pre-gluing 0.785 Hz 0.709 Hz 0.949 Hz 0.975 Hz Post-gluing 0.789 Hz 0.705 Hz 0.953 Hz 0.984 Hz

According to the calculations from ELOG 12316, this pitch frequency implies the support point is 0.317mm lower than the design value of 0.985mm. (However, this is just an approximation and does not include the fact that each standoff is at a different height.)

Nevertheless, this difference is frequency is not so large that the dynamics of the suspension will be qualitatively changed in some important way; really, the pitch frequency is just ~1.5dB lower. So, I deemed our standoff gluing a success, removed the optic from the suspension, and placed it in an optic holding ring after giving the top of the barrel a gentle drap wipe with some iso. At this point, I used the microscope to look at the ruby standoff groove. As far as I can tell, no glue has invaded the groove - it looks sharp as ever. (whew)

I also wiped the wire with acetone and easily removed the glue droplets. However, I noted that (as is the case for ETMY) the wire is deformed at the points where it was in contact with the standoffs. I wonder if we should re-suspend with new wire, or accept the current deformed wires.

In any case, we can now move on to air baking the ETMX tower and gluing the stray magnet back onto ETMY.

Attachment 1: ETMX_resonances.pdf
Attachment 2: ETMX_SUSspectra.zip
12384   Tue Aug 9 00:44:43 2016 gautam UpdateSUSETMY patch-up

Summary:

Given that ETMX looks to be in good shape and the optic and suspension tower are ready for vacuum and air bakes respectively, I set about re-gluing the knocked off magnet of ETMY. In my previous elog, I had identified the knocked off magnet as the UL magnet. But in fact, it was the LR magnet that broke off. This is actually one of the magnets that was knocked off when Johannes was removing the optic from the vacuum chamber. I have edited the old elog accordingly.

Step 1: Removing epoxy residue

• I used the teflon+glass rig Steve put together for this purpose
• After soaking for ~2 hours in acetone, I was able to remove approximately half of the ring residue by lightly pushing with a wipe.
• The other half wouldn't budge so I let it soak for another 4 hours
• After 6 hours of soaking, I was able to get all of the epoxy residue off - it doesn't simply dissolve in the acetone, I had to push a little with one of the cotton-tipped paddles in the cleanroom
• I gave the portion exposed to acetone a quick drag wipe with isopropanol. I didn't spend too much time trying to clean the AR side given that we will be using first contact anyways.
• I have not touched the HR side for now, even though a small portion of it was exposed to acetone. While cleaning the HR face with first contact, this portion can be inspected and cleaned if necessary

Step 2: Putting the optic in the magnet gluing jig

• I transferred the optic to the magnet gluing jig
• Given that we weren't touching any side magnets, I reasoned I did not have to go through the elaborate shimming routine to account for the wedge of the optic that we had to do in the recent past
• However, I did not think to put a thicker teflon spacer on the lower side of the wedge, and as a result, I knocked off the UR magnet as well as the jig did not have sufficient clearance
• Fortunately, the UR magnet came off cleanly, there was hardly any epoxy residue left on the optic. The UR magnet was NOT one of the magnets knocked off by Johannes while removing the optic from the vacuum chamber
• I gave the area formerly occupied by the UL magnet 3-4 wipes with acetone and then 1-2 wipes with isopropanol
• At this stage, I proceeded to re-insert the magnet-gluing jig. I used the two scribe lines on the outer side of the jig to fix the rotation of the jig, and used the remaining two attached face magnets to fix the overall position of the jig (by centering these magnets relative to the apertures on the jig). In order to center well, I had to unscrew the stuck silver plated screw on the jig by 1 turn
• Having arranged the jig satisfactorily, I proceeded to remove epoxy residue off the dumbbell of the recently knocked off UL magnet using first a razor blade, then sandpaper and finally made some new grooves with a razor blade. I then cleaned the surface of the dumbbell to be in contact with the optic with isopropanol. All of this was done for the LR magnet two weeks ago right after it was knocked off

Step 3: Gluing the magnets

• I prepared the magnets in the pickle pickers
• I discarded 1 full squeeze of the epoxy after it reached the tip of the mixing fixture, and then extracted another full squeeze of the gun for mixing and gluing the magnets
• I mixed the epoxy in an Al foil vessel for 3-4 minutes, and then placed a few drops on a piece of Al foil for a test bake at 200F for ~15 minutes
• The test bake went well, so I proceeded to apply glue to the dumbbells and re-glue the magnets to the optic
• The gluing was done around midnight, so we should be able to have a look at this post lunch tomorrow.

Provided the gluing goes well, the plan for tomorrow is:

1. Bring ETMY suspension tower from the vacuum chamber to the cleanroom along with its OSEMs
2. Suspend ETMY with a new length of wire (this should be much more straightforward than our ETMX exploits as both standoffs are already glued)
3. Insert OSEMs, check that all 4 face magnets are well centered w.r.t. their coils and also that at least one side magnet is well aligned relative to its coil and can be used
4. If step 3 goes well, then ETMY is also ready for a vacuum bake. I guess we can also air bake the ETMY suspension tower, there's plenty of room in the oven
12386   Tue Aug 9 15:27:57 2016 gautam UpdateSUSETMY patch-up

The pickle pickers came off nicely and both magnets seem to be glued on okay. The alignment of the face magnets look pretty good, but we will only really know once we suspend the mirror, check the pitch balance, and put in the OSEM coils.

I brought the ETMY suspension tower + OSEM coils out of the vacuum chamber into the cleanroom. Given that the old wire had a pretty sharp kink in it, I removed it with the intention of suspending the optic with a new length of wire. I noticed a few potential problems:

Attachment #1 - ETMY tower is different from ETMX tower:

• The ETMY suspension seems to be of an older generation - it does not have the the two secondary wire clamps.
• The top piece was attached to the body of the tower using non-silver-plated screws. Steve tells me this is the wrong type, and we can switch these out when we put it back together.
• The wire clamp itself doesn't have much of a groove from the wire. But the wires have made asymmetric grooves in the tower itself (the left groove is deeper than the right as seen in Attachment #1), that are clearly visible. Should we get these grooves removed before attempting re-suspension? How do we want to remove it? Steve thinks the best option is to send it to the shop for milling, as there is hardly any room to rub sandpaper along the piece because of the pins, and these pins don't come out.
• Or do we just not care about these grooves for now, if we are planning to use new wire anyways after air-baking the towers?
• Steve thinks we should have a few spares of these top blocks handy (the latest version, with the secondary clamps), he wants to know if we should place an order for these (we already have 10 spare wire clamp pieces available for if/when we need them)

Attachment #2 - the base of the tower is significantly rusty:

• A few wipes with an acetone soaked rag yielded quite a lot of rust
• Steve thinks this is because the wrong type of stainless steel was used
• Does this have to do with the cage being of an older variety? After a few vigorous wipes, no more rust came off, but the rusting process will presumably keep generating new rust? Is this a concern? Do we want to change this piece before putting the tower back in?

I am holding off on attempting to re-suspend the optic for now, until we decide if the old wire grooves need to be removed or not. If we are okay with re-using the same piece as is, or if we are okay with using sandpaper and not the machine shop to remove the grooves, I will resume the re-suspension process.

Eric suggested another alternative, which is to use the old ETMX tower. I don't recall it being rusted, but this has to be checked again. The other problem of the wire-grooves would possibly still be an issue.

Regarding the vacuum bake of the ETMs, Bob tells us that the best case scenario we are looking at is September.

Attachment 1: IMG_2996.JPG
Attachment 2: IMG_2997.JPG
12388   Tue Aug 9 16:19:27 2016 SteveUpdateSUStorque driver for wire clamp

New Wiha 28504 torque wrench for SOS wire clamping. It's range 7.5  - 20 in-lb in 0.5 steps [ 0.9 - 2.2 Nm ] Audible and perceptible click when the pre-set torque has been attained at ±6% accuracy.

The new ETMX sus wire torqued to ~ 11.5 in-lb [1.3 Nm ]

 Quote: Gautam and Steve, The clamp's left side was jammed onto the left guide pin. It was installed slit facing left. Gautam had to use force to remove it. The clamp should move freely seating on the guide rods till torque aplied. Do not move on with the hanging of optic with a jammed clamp. Fix it. Never use force as you are hanging - aligning optic. The clamp is in the shop for resurfacing and slit opening.

12390   Wed Aug 10 03:08:03 2016 gautam UpdateSUSETMY patch-up

[lydia, gautam]

Rana felt it was alright to use the wire clamp and suspension cage in its existing condition for checking the ETMY magnet-OSEM coil alignment. So we set about trying to re-suspend ETMY. The summary of our attempts:

• Transferred optic from magnet gluing rig to the suspension cage
• Adjusted bottom EQ stops till the scribe lines on both sides were at 5.5" as verified with the microscope
• Looped cleaned length of wire around optic, attached free ends to winches, placed the wires under light tension by finger-pulling the slack out
• Lowered the bottom EQ stops
• Winched the optic to the right height
• Clamped the wire with the only wire clamp on this variant of the suspension cage. We used the same torque wrench at the same torque setting as was successful for ETMX. But after removing the winches, and releasing the face EQ stops, the optic seems to have sagged a lot - it now touches all the bottom EQ stops, and the more I lower it, the more it seems to come down. Perhaps it is the effect of the wire grooves in the cage, or that the wire-clamp itself is slightly different from the piece used on the ETMX cage, but 1.3Nm of torque doesn't seem to have tightened the wire clamp sufficiently
• We can still probably salvage the situation by re-attaching the winches to the top of the cage, setting the optic to the right height again, and clamping the wire clamp with more torque (as this is just a check to see that the reglued magnet configuration is compatible with the OSEM coil positions on the cage). Before air baking the cage, we will have the old wire grooves removed, and then suspend the optic with a fresh loop of wire after the bake
• We could not check the magnet-OSEM alignment because of the slipping of the wire through the clamp. We decided against pushing on tonight
• Optic is currently in the cage, resting on the bottom EQ stops and with all face EQ stops within 1mm of the optic. The OSEM coils have not been inserted into the holders

Regarding the vacuum bake of the optics: why do we want to do this again? Koji mentioned that the EP30-2 curing process does not require a bake, and there is also no mention of requiring a vacuum bake in the EP30-2 gluing guide. Is there any other reason for us to vacuum bake the optic?

12392   Wed Aug 10 15:34:24 2016 SteveUpdateSUS6 in-lbs torque driver for wire clamp screw

The 7.5 in-lb of Wiha seems at the upper end of torque range for a 4-40 SS screw

Wiha 28502 ordered with range 5 -10 in-lb for silver plated 4-40 screws

Do not trust the Venzo torque wrench under 2 Nm ! It miss lead me.

Recommended torque values for silver-plated fasteners are here. For aLIGO we use the guidelines in T1100066-v6, This doc is posted in 40m wiki under Mechanics also.

So, we'll use 6 in-lbs  on silver plated 18-8 stainless steel socket head cap screw 4-40 x 3/8 into SS tower bridge.

Please replace these clamp screws every time if they were tightened without a torque wrench.

Quote:

New Wiha 28504 torque wrench for SOS wire clamping. It's range 7.5  - 20 in-lb in 0.5 steps [ 0.9 - 2.2 Nm ] Audible and perceptible click when the pre-set torque has been attained at ±6% accuracy.

The new ETMX sus wire torqued to ~ 11.5 in-lb [1.3 Nm ]

 Quote: Gautam and Steve, The clamp's left side was jammed onto the left guide pin. It was installed slit facing left. Gautam had to use force to remove it. The clamp should move freely seating on the guide rods till torque aplied. Do not move on with the hanging of optic with a jammed clamp. Fix it. Never use force as you are hanging - aligning optic. The clamp is in the shop for resurfacing and slit opening.

12397   Wed Aug 10 23:45:03 2016 gautam UpdateSUSETMY re-suspended

Summary:

• ETMY has been re-suspended
• Reglued magnets (and also those that weren't knocked off) quite well with OSEM coils (see attachments)
• Pitch balance is off by ~2.8mrad (8mm over 1.5m lever arm) after inserting and centering OSEMs
• The same damping scheme used during the ETMX re-suspension process works reasonably well with ETMY as well

Details:

• I suspected that I had not tightened the wire clamp enough yesterday, and that the wire had slipped once the winches were removed
• Steve and I looked into the torque wrench situation today, and I realised that I had not been using the torque wrench correctly. What I thought were clicks indicating that the set torque has been reached was in fact just the sound the piece makes when going the opposite way relative to the direction set by the clip on the torque wrench. Anyways, the point is that while I thought I was tightening the screws with ~1.3Nm of torque, what was actually being applied was much less (although I don't have a good way to quantify how much less)
• So today I put the winches back on top of the tower, and winched the optic back up to the correct height using the ususal scribe line + microscope prescription
• I then tightened the wire clamp by hand. This is obviously not very repeatable, but it will have to do until we get a torque wrench with the correct range
• This seems to have done the trick - I did the tightening shortly after lunch, and after ~10 hours, there is no evidence of any wire sag
• I then proceeded to insert the OSEMs, first not all the way in to check the clearance available to the magnet, and once I was satisfied there was no danger of knocking anything off, went ahead and inserted the coils till the PD readouts were approximately half of the maximum (i.e. fully un-occluded) values. I used the OSEM coils originally on the ETMY tower, but all the other readout and drive electronics in the signal chain (satellite box included) belong to the ETMX setup (so as to avoid any cable routing over 80m from the Y end to the cleanroom). After some adjustment of the OSEM holding plates, I was able to center the magnets relative to the coils
• The tower only allows for a side OSEM to be inserted on one side. The other side does not have a threaded hole for a set screw. So we are forced to use the reglued magnet and not the side magnet that was not knocked off. By eye, it looks like the magnet may never completely occlude the LED, but the Striptool trace I was using to monitor the output of the PD did not yield any conclusive evidence. The optic was moving around a lot and I did not perform this check after turning the damping on
• I was able to damp the optic as well as we were able to damp ETMX on the clean bench (with the HEPA turned OFF). I had to turn the YAW gain down from 100-->75 to avoid some oscillations
• I then proceeded to check the pitch balance with the HeNe. The spot is low on an iris 1.43m away by ~8mm, which corresponds to a pitch misalignment of ~2.8mrad. I am not sure what to make of this - but perhaps its not unreasonable that we see this? Is there any record of what fine pitch balancing was achieved when the optic was put together back in 2010? This is also very sensitive to how far in/out the OSEM coils are, and though I've tried to center the coils as best as I can, I obviously have not done a perfect job...

What's next?

• Is the observed pitch imbalance a deal breaker? If so, I guess we need to re-glue a standoff?
• Are we willing to accept the side OSEM situation? (Tomorrow, I need to do a check to see what, if any, dynamic range we lose, with the damping on)
• If both the above are not problems we need to worry about, then:
• ETMY + ETMX -------> Vacuum bake on 22nd August (? - Bob also told me earlier today that he will try and put in some old turbo pump next week, and if that works, we could possibly get in the queue even before the 22nd)
• ETMY tower -------> Steve for sanding and removing wire grooves -------> Air bake
• ETMX tower -------> Air bake (provided the latest round of wire tightening has not left any grooves in the top piece of the tower, if it has, this needs to be cleaned up too)
• Some lengths of SOS wire (for re-suspending optics after bake) -------> Air bake

Attachments:

Attachment #1: Striptool trace showing all OSEM coils have been pushed in till the PD readout is approximately half the fully open value

Attachment #2: Pitch balance is off by ~2.8mrad (the Iris center is 5.5" above the table)

Attachment #3: UR magnet

Attachment #4: UL magnet

Attachment #5: LR magnet

Attachment #6: LR magnet

Attachment #7: SD magnet

Attachment 1: ETMY_OSEMStrip.PDF
Attachment 2: IMG_2998.JPG
Attachment 3: IMG_3000.JPG
Attachment 4: IMG_3001.JPG
Attachment 5: IMG_3002.JPG
Attachment 6: IMG_3003.JPG
Attachment 7: IMG_3004.JPG
12398   Thu Aug 11 00:20:41 2016 KojiUpdateSUSETMY re-suspended

How much pitch bias do you need in order to correct this pitch misalignment?
That may give you the idea how bad this misalignment is.

12401   Thu Aug 11 11:56:40 2016 gautamUpdateSUSETMY re-suspended
 Quote: How much pitch bias do you need in order to correct this pitch misalignment? That may give you the idea how bad this misalignment is.

I needed to move the pitch slider on the IFO align screen to -2.10 (V?) from 0 to get the HeNe spot to the center of the iris. The slider runs from -10V to 10V, so this is something like 10% of its range. I am not sure if it means anything, but the last saved backup value of this pitch slider was -3.70. Of course, application of the bias will affect all the coils, and when the optic is pitch balanced, the lower magnets are a little too far out and the upper magnets are a little too far in (see Attachment #1), as we expect for a downward pitch misalignment to be corrected. I suppose we can iteratively play with the coil positions and the bias such that the coils are centered and we are well balanced (maybe this explains the old value of -3.70).

I also checked that the side magnet can completely occlude its PD. With the damping on, by pushing the coil all the way in, the output of the side PD went down to 0.

Attachment 1: pitchBalancingWithBias.PDF
12409   Mon Aug 15 14:29:32 2016 SteveUpdateSUSSOS sus wire ordered

The wire will arrive in 1-2 weeks. It is a new production. Brad Snook of Ca Fine Wire was suprised that we are still using the 13 years old wire.  Oxidation is an issue with iron contained steel wire.

He would not give me a shelf life time on it. He recommended to check the strenght of it before usage. It passed with safety factor of 2 just recently.

In the future we'll store the new spool in oxigen free nitrogen environment..

 Quote: 0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will on 9" OD. spool too.

12410   Mon Aug 15 14:34:33 2016 ericqUpdateSUSSOS sus wire ordered

We have indeed seen numerous tarnished/rusty points along the wires, and just tried to choose lengths free of any of these. I wonder if this can explain the brittleness/ease with which we've been breaking it. My feeling is that we should use the newer wire if feasible.

12411   Mon Aug 15 18:28:15 2016 gautamUpdateSUSAir-bake preparation

I assume that we are prepared to live with the pitch bias situation of ETMY (i.e. we can achieve a configuration in which there is some pitch bias to the coils, and the OSEMs are inserted such that the PD outputs are half their maximum value). Or at least that we don't want to go through the whole standoff-regluing procedure for ETMY as well.

So today I took the optic out, and began to make some preparations for the air bake.

• Both optics are now sitting in their respective metal donuts.
• How do we want to bake the optics? Bob has said he has prepared the oven for this bake, and that he has configured the temperature controller to a setpoint of 34C, and a ramp time of 2 hours to reach that temperature from lab temperature (we should check this before putting the optics in there with our independent temperature sensor - also, he is away for the week now so we can't get his input on any of these). But what about the actual logistics of how the optics are going to be housed? Specifically:
• Do we want the donut to sit on some sort of tray? Presumably it is not ideal to have the HR surface in close proximity to the oven floor?
• Does the oven need any special cleaning?
• Do we cover the donut+optic setup with a glass jar? If we do, any particles we eject off the optic can't escape the confines of the bowl, and if we don't, detritus from elsewhere may settle on the optic?
• How long do we want this bake to last? 24hours? 48 hours? Bob didn't have an answer when I asked him earlier in the afternoon...
• I also removed the suspension block from the top of the towers of both ETMX and ETMY, so that Steve could work on sanding them before we acetone-wipe and bake the towers themselves.
• It was very apparent that the weights of the two pieces were largely different (ETMY suspension block ~350g, ETMX suspension block ~960g), even though they have the same physical dimensions.
• Investigation into why this was yielded nothing conclusive. But Steve and I think that the ETMY suspension block is made out of Aluminum rather than SS, which would explain why the wire grooves seem deeper in the ETMY piece than the ETMX piece. It is worth noting that the specification calls for SS and not aluminum. But the top piece of the ETMY suspension (and indeed the old ETMX suspension) looks different from the specification, in that they don't have tapped holes for the secondary wire clamps (see Attachment #1).
• I'm not sure if this is important, but it is worth noting. Steve and I also checked the remaining suspension towers. We think that ITMY, BS, SRM and PRM have the correct (to specification) suspension block. We couldn't get a look at ITMX and didn't want to take the door off. So ETMY (and possibly ITMX) will be the only suspension(s?) with a different suspension block.
• Steve's sanding efforts did not go ideally.
• He was successful in removing the wire grooves.
• But the sharp edge which is supposed to clamp the wire seems to have been rounded a little bit (see Attachment #1).
• Overall, the section that we was sanded looks lower (i.e. its like we've dug a small channel into the plane of the suspension block)
• Given that we suspect the ETMY suspension block is Aluminum, it is likely that attempting to sand it will yield an even deeper channel.
• Do we want to bake the suspension towers in the large baking oven? Presumably we don't want to bake the optics with anything else. But does the large oven need any special cleaning before we stick the towers in there?
• ETMY has some acetone marks on it. I will try and have this removed by drag wiping with more acetone and isopropanol prior to the bake tomorrow. Anyways we will first-contact clean the HR (and AR) sides after the bake before installing the optic.

In summary, the questions that remain (to me) are:

1. Are we okay using an Al suspension block?
2. How perfectly do we want wire grooves from prior suspensions removed? It looks like sanding doesn't work well, do we want to consider sending this into the shop?
3. Baking logistics, as described above.

I think we can start the baking of the optics tomorrow. The timeline for the suspension towers is unclear, depends on how we want to deal with the sanding dilemma.

Attachment 1: IMG_6816.JPG

The SOS ETMY tower had and Aluminum bridge. How is it possible that this was true? Is SS better than Al for some quantitative scientifc reason ???

Their weight ratio as measured  =  922 / 307 g = 3

Destinies:  SS 304 / Al 6061  >  0.289 / 0.098  [ lb /in3 ] =  2.94

Attachment 1: AlBridge.jpg
12415   Tue Aug 16 21:54:27 2016 gautamUpdateSUSAir-bake - IN PROGRESS

I put in both ETMX and ETMY into the air-bake oven at approximately 8.45pm tonight. They can be removed at 8.45am tomorrow morning.

• Given that we had previously melted a thermocouple in this oven, and there have been no high temperature bakes in it since, we ran the oven at 100C for about 3 hours in the afternoon
• After that, I left the oven door open for an hour for the interior to return to room temperature
• I then re-connected the controller (which doesn't seem very precise, it pulses the AC power to the oven in order to control the temperature), and dialled the oven back down to heating level 4, which is what Bob had it set at. I then waited for a couple of hours for the oven to reach ~34C
• Before putting the optics in, I gave the inside of the oven a quick wipe with a clean wipe, and palced a layer of Al foil on the bottom of the oven
• The optics are sitting on their donuts (see Attachment #1) - the copper wire elevates the optic+donut slightly and provides a path for air flow
• ETMY was drag wiped with acetone+isopropanol prior to baking (to remove acetone stains from soaking to remove epoxy residue
• We will of course be cleaning the optics with first contact prior to re-installation in the vacuum chambers
• I am not sure what the extra cylindrical piece in there is, but Bob advised me to leave it in there so that's what I did
• I've observed the temperature over ~2hours since I first put it in, and the oven/controller isn't going bonkers, so I'm trusting the controller and leaving for the night
Attachment 1: IMG_3005.JPG
12416   Wed Aug 17 08:47:43 2016 ericqUpdateSUSAir-bake finished

I turned off the air bake oven at 8:45AM. I'll leave the optics alone for a bit while it cools.

12419   Wed Aug 17 22:09:04 2016 ranaUpdateSUSSOS sus wire ordered

Not really true that it passed. That's just an arbitrary margin. Best to throw away all the old wire. We have no quantitative estimate of what the real torque should be. Its just feelings.

 Quote: The wire will arrive in 1-2 weeks. It is a new production. Brad Snook of Ca Fine Wire was suprised that we are still using the 13 years old wire.  Oxidation is an issue with iron contained steel wire. He would not give me a shelf life time on it. He recommended to check the strenght of it before usage. It passed with safety factor of 2 just recently. In the future we'll store the new spool in oxigen free nitrogen environment..

12420   Wed Aug 17 23:00:57 2016 gautamUpdateSUSAir-bake of towers

I just put in the following into the air bake oven for a 12 hour, 70C bake:

• ETMX and ETMY cages (with sanded suspension blocks loosely tightened for now, we will tighten them after the bake)
• 13 new wire clamps that were recently made by the shop
• 7 lengths of suspension wire (since the new wire is unlikely to arrive for another 2 weeks). This should be sufficient in case we overtighten the wire clamps a couple of times and the wire snaps.

I put these in at 10.30pm. So the oven will be turned off at 10.30am tomorrow morning. The oven temperature seems stable in the region 70-80 C (there is no temperature control except for the in built oven control, I just adjusted the dial till I found the oven remains at ~70C.

Tomorrow, we will look to put on first contact onto the ETMs, and then get about to re-suspending them.

Attachment 1: IMG_3006.JPG
12421   Thu Aug 18 08:17:16 2016 SteveUpdateSUSwire clamping preparation

The wire inprints were removed by 800P grain paper [Norton 73568] The SS bridge block now has an undesireble vally in the wire location.

The sus bridges were soaked in acetone over night and sonicated to remove residual sand paper.

 Quote: I just put in the following into the air bake oven for a 12 hour, 70C bake: ETMX and ETMY cages (with sanded suspension blocks loosely tightened for now, we will tighten them after the bake) 13 new wire clamps that were recently made by the shop 7 lengths of suspension wire (since the new wire is unlikely to arrive for another 2 weeks). This should be sufficient in case we overtighten the wire clamps a couple of times and the wire snaps. I put these in at 10.30pm. So the oven will be turned off at 10.30am tomorrow morning. The oven temperature seems stable in the region 70-80 C (there is no temperature control except for the in built oven control, I just adjusted the dial till I found the oven remains at ~70C. Tomorrow, we will look to put on first contact onto the ETMs, and then get about to re-suspending them.

Attachment 1: 800P.jpg
12422   Thu Aug 18 14:14:20 2016 gautamUpdateSUSAir-bake of towers - finished

I took the two cages, wires and wire clamps out this morning, back into the cleanroom after their 12 hour 70C bake.

I've also applied first contact to the AR face of the optics. Steve is preparing a jig which will allow us to apply first contact on the HR side with the optic horizontal. The idea is to apply a large coating first, to clean the bulk of the HR surface, and peel it off before re-suspending the optic. Then we can paint on a smaller area, suspend the optic (and hope the pitch balancing is alright) before taking the whole assembly into the chamber where it will be peeled off.

Calum recommended that we buy a new ionizing gun + electrometer assembly (apparently our current set up is woefully obsolete) but I don't know if we can have these in time for the first contact peeling...

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