Ruby wire standoff 1 mm od. with V-groove test cut. SOS sus wire 0.0017" od. is in the background.
It looks almost OK, but we need a bit sharper picture for both the groove and thw wire.
Kate Dooley picked up this item today.
The enclosure top piece in the middle is still in the machine shop.
The carpenter who helps in the built just left for one week vacation.
The unit will be ready on April 1
I'd prefer doing the installation with the enclosure on the new table.
It's the only way to minimize the resonances of the enclosure with shimming.
Recent EQ 4.8 mag San Felipe, Mexico trips PRM sus damping.
PRM damping restored. PMC locked.
Local earth quake 3.1 magnitude in Valencia, Ca did not trip our suspensions.
The ruby wire standoff V groove cuts are looking good.
I will request free sample of sapphire prizm where one side would have SOS's R cylindrical surface.
The present plan to have the v-groove on this prism.
Earth quake stops need viton tips.
Wirestandoffs are still aluminum.
Bah, we need ruby slippers for all future suspensions. Prism with curved backside and smooth grooves.
No aluminum, no cry.
May 23, 2016 ITMX dead He/Ne laser sn P845648 replaced after 1062 days [2.9 yrs] by 1103P, sn P859884, with output 2.6 mW, nicely round beam quality at 15 meters.
Power just before viewport 1 mW, returning light on qpd 154 microW = 7,500 counts
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.
I did a quick measurement of the ITMX oplev loops, both pitch and yaw have about the same upper UGF as previous measurements with the previous laser; about 4 Hz.
Local EQ 3.5 mag at 2:28 UTC May 24, 2016 Rancho Cucamonga, Ca.....no damage
There are some issues with 5 mm sapphire prism Atm5. It will cause interference between one of the prisms and the Side OSEM.
Here are some drawings to see the issues with larger wire standoff.
The 2 mm prism will work.with a 1 mm longer dumbell.
Quotes requested from http://photomachining.com/laser-micromachining-photomachining-contact.html and http://www.optocity.com/
Gap of the prism from the mirror
Sag: s = R(1-Cos[ArcSin[d/2/R]])
- Mirror curvature sag for 2mm prism (R=37.75mm): s=13um
- Minimum gap: 20um => s=33um => R=15mm
- Nominal gap: 35um => s=48um => R=10mm
- Maximum gap: 50um => s=63um => R=8mm
The second figure shows somewhat realistic arrangement of the pieces
Local EQ 3.1 mag at Jun 2, 2016 11:06:16 PM UTC, Muscoy CA........no damage
Our STS should seen this shake.
EQ 5.2 mag at Jun 10, 8:04 am UTC, Borego Spring, CA ~150 mi away.........no obvoius damage, damping restored, MC is locking, arms are flashing
ETMX has been jumping around again lately. Just now, I zeroed the ETMX alignment offsets in the SUS model, and centered the ETMX oplev spot via slow machine sliders. OSEM damping is on, oplev damping is off. Let's see how it moves around in the next day or so.
UTC: Jun 10 2016 23:18:26
Within two hours, it was already all over the place.
What about ETMY? and are these really microradians or just some made up cal?
(on tower )
buy Ni coated ones for future use from www.electroenergy.com
Ok for larger RUBY,
unit is not in perfect condtition but usefull
Pick up FC from Gary with purchasing date 7-7-2015
NOT finished, last edited 7-7
No suspention lost damping.
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.
NOT finished, last edited 6-28
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.
Hi Steve -
I found the doc I was looking for:
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.
ps: there is no existing fixture to hold SOS optic while soaking it
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
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:
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.
Things mentioned in the procedure I have not found:
Some other tasks and their status:
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.
Glass soaking dish with teflon guides.
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.
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 )
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.
(wiki link: https://wiki-40m.ligo.caltech.edu/Suspensions/Mechanical_Resonances)
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:
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:
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.
ITMY side : Magnet od 1.9 mm so wire to magnet gap ~ 0.2-0.3 mm
July 27, 2016 2 new 1103P from Edmonds in: P947034 & P947039, manf. date April 2016,
While tightening the bolts on the ETMX wire clamp, the wire broke. All four face magnets broke off.
Fortunately, no pieces were lost.
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.
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.
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
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.
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)
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.
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.
[lydia, steve, ericq, gautam]
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.
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.
[lydia, ericq, gautam]
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.
Part 1: Rotation of optic
Part 2: Replacement of holder for top pair of OSEMs
Part 3: Fine pitch balancing
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):
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?
0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will be on 8" OD. spool too.