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ID Date Author Type Categoryup Subject
  12269   Thu Jul 7 16:05:55 2016 KojiUpdateGeneralSUS Vmon

Ah, thanks. That makes sense. In that case, we should remove the texts "30Hz HPF" from the suspension screens.

Now we just need AA LPFs for these channels, or hook them up to the RT system.

  12270   Thu Jul 7 17:12:50 2016 JohannesUpdateGeneralVent progress

I performed a visual inspection of ITMY in its natural habitat today. I did not get any great pictures from the HR side because it's located very towards the edge of the table towards the arm. Before that I checked the levelness of the table. East-west direction was fine, north-south was slightly off but still within the marks for 'level'.

The AR side had several speckles, a few of them located somewhat near the geometrical center of ITMY. The top of the barrel was worse of, as expected. The HR side was a little better, but there were a few pieces of dust? near near the center. Sample pictures are attached, I uploaded all the good ones to Picasa.

Clamps that mark the position of ITMY were already in place. I did not move the optic just yet, and we will have to move a cable block out of the way to bring ITMY near the opening for us to work on it. We will markt the position of that to preserve the weight distribution. Then we can probably take some better before/after pictures. Tomorrow I will be looking at ETMY.

  12271   Fri Jul 8 11:35:45 2016 gautamUpdateGeneralVent progress - ETMX SUS Coil driver electronics investigation

Yesterday, I expanded the extent of the ETMX suspension coil driver investigation. I set up identical monitors for two more coils (so now we are monitoring the voltage sent to UL, UR and LL - I didn't set one up for LR because it is on a second DB25 connector). Furthermore, I increased the excitation amplitude from ~20 to ~2000 (each coil had an independent oscillator at slightly different frequency between 5Hz and 8.5 Hz), the logic being that during LSC actuation we send signals of approximately this amplitude to the coils and we wanted to see if a larger amplitude signal somehow makes the system more prone to glitches.

Over ~10 hours of observation, there is no clear evidence of any glitch. About 2 hours ago (~930am PDT Fri Jul 8), the watchdog tripped - but this was because even though I had increased the trip threshold to ~800 for the course of this investigation, megatron runs this script every 20 minutes or so that automatically reduces this threshold by 17 counts - so at some point, the threshold went lower than the coil voltage, causing the watchdog to trip. So this was not a glitch. The other break around 2am PDT earlier today was an FB crash.

Do we now go ahead and pull the suspension out, and proceed with the swap?

  12272   Fri Jul 8 11:48:09 2016 KojiUpdateGeneralVent progress - ETMX SUS Coil driver electronics investigation


Move the suspension on the south clean bench and make more close inspection. We need to remove the OSEMs.

Then unmount the mirror. Bring it to the clean room and work on the bond removal.
Meanwhile, set up all suspension components inclusing the alignment test setup.

  12273   Fri Jul 8 13:01:23 2016 AakashUpdateGeneralAcromag is talking ! | SURF 2016

Acromag is talking now, after few changes to the original EPICS configuration and cross compile configuration. Modbus config files also were changed and compiled again to run it on linux-arm architecture. I have made use of pyModbus for the final work and I am planning to use the same for grabbing channels. Though I am unable to grab channel data right now, I am able to communicate to it over ethernet and send and receive data. 

  12274   Fri Jul 8 14:03:26 2016 ericqUpdateGeneralETMX removed from suspension

ETMX is currently in the clean room, the barrel is the tiniest bit submerged in acetone that will remove a guide rod, standoff, and side OSEM. 

Additional inpsection of the standoffs on the flow bench did not provide any insight, pictures are in picasa. Here is a cropped version of a picture we took:


We should look at them under a microscope.

  12276   Fri Jul 8 16:33:26 2016 ericqUpdateGeneralETMX removed from suspension

The magnet, guide rod, and standoff came off without too much force. However, some epoxy residue remains on the barrel. I didn't really want to scrape it off, so I've opted for more soaking. Much of the acetone had evaporated already, so I put some more - just to the point where the residue is submerged. 

  12278   Fri Jul 8 20:44:09 2016 KojiUpdateGeneralETMX removed from suspension

In the evening, I went into the clean room to check how it goes.

- The air around the table is quite warm like a hell. Is this normal?

- I checked how the scattered epoxy spots look like. They were not touching the bath anymore due to evaporation.
- I scraped the spots with the tweezers there. They were easily removed. The particlates on the side barrel were wiped by a wipe with aceton. (Result: Attachment 3)

- Then looked at the other side. I poked the standoff with the tweezer. It was easily removed. I don't think the bond was too weak. Just the area of the bond was so tiny.
- Also residue was scraped by a tweezer and wiped with a cloth. (Attachment 2)

- The removed stand off is in the stainless bowl together with the parts that Eric removed.

- I didn't want to leave the optic in the aceton fume. It was placed on a metal donuts for a 3" optic. (Attachment 4)

- I couldn't find a vacant clean glass jar for the lid. So, a foil hut was built. We should be very careful not to scratch the optic when we remove the hut. (Attachment 5)

- The aceton bath was covered with the foil as it was. (Attachment 6)

  12281   Fri Jul 8 21:22:38 2016 gautamUpdateGeneralVent progress - ETMX SUS Coil driver electronics investigation

While ETMX is out, I'm leaving the larger amplitude excitations to the coils on over the weekend, in case any electronic glitch decides to rear its head over the weekend. The watchdog should be in no danger of tripping now that we have removed the ETM.

Unrelated to this work: while removing the ETMX suspension from the chamber, I also removed the large mirror that was placed inside to aid photo taking, so that there is no danger of an earthquake knocking it over and flooding the chamber with dust.

  12283   Sun Jul 10 15:38:01 2016 ericqUpdateGeneralETMX in guiderod/standoff gluing fixture

I was hoping to glue a standoff and guide rod today, but some problems have reared their heads. Story follows:

Upon first placng the optic into the standoff gluing fixture, I was presented with a geometric problem. In the assembly procedure, one glues the rods before the magnets, which prevents a situation like this:

When what you want to do is this:

So, I spun the optic around such that the magnet is on the far side of the scribe line from the side arm, and instead of extending the side arm past the scribe line, will bring it back towards the near side. I also swapped the arms of the fixture such that the guide rod will be glued on the opposite side of the optic than the side magnet, so the side magnet won't get in the way when doing the pitch adjustment of the second standoff.

Then, I found the scribed ruby rods, and took a look at one under a microscope. The groove looks nice and sharp. I placed the standoff in the side arm of the fixture.

However, the fact that the groove does not go all the way around the standoff leads to problem #1: when adjusting the position of the side arm, the standoff seems to roll around unpredictably, making it hard to deterministically position it while keeping the groove facing outwards. 

Problem #2 is not too surprising give Steve's finding about the guide rod holding arm in ELOG 12264. Given that the tip is banged up, the guide rod does not sit straight in the arm, making it crooked. This would lead to the second standoff's groove not being well aligned to the suspension wire.

I will meditate on solutions to these problems... I have covered the optic and fixture with the same foil hut Koji made on Friday.

Also, I peeked at the aluminum standoffs under the microscope. Since the groove goes all the way around, we don't really know where the wire was seated before. Still, there are some places where the groove looks kind of worn:

  12285   Sun Jul 10 17:33:00 2016 ericqUpdateGeneralVent progress

It took a little time, but I relocked the IMC and realigned to the point where the PRC is flashing, visible on REFL and AS, and tiny flashes are visible in TRY.

  12289   Mon Jul 11 15:13:22 2016 gautamUpdateGeneralVent progress: in-date First Contact procured

I have obtained 2x100cc bottles of in-date first contact from Garilynn (use before date is 09/14/2016) for cleaning of our test-masses. They are presently wrapped in foil in the plastic box with all the other first contact supplies.

  12290   Tue Jul 12 09:18:12 2016 ericqUpdateGeneralSlippery substance mystery

I found a note on Steve's desk that R. Abbott left yesterday afternoon about an unidentified slippery substance being present on the floor by cabinet S12, along the X arm. (Steve is away this week)

Just now, I found no trace of the substance in the vicinity of that cabinent (which is one of the cabinets for clean objects). Maybe the janitor cleaned it already?

  12291   Tue Jul 12 09:35:51 2016 JohannesUpdateGeneralSlippery substance mystery

I've noticed the spot that Rich means before, too. I think you only notice this when you're wearing the shoe covers, not sneakers or crocs. I didn't see any 'substance', it seems more like the floor finish (wax?) seems to be more slippery in that area than others.


I found a note on Steve's desk that R. Abbott left yesterday afternoon about an unidentified slippery substance being present on the floor by cabinet S12, along the X arm. (Steve is away this week)

Just now, I found no trace of the substance in the vicinity of that cabinent (which is one of the cabinets for clean objects). Maybe the janitor cleaned it already?


  12292   Tue Jul 12 16:08:00 2016 ericqUpdateGeneralETMX ruby guided gluing

[ericq, Koji]

We have positioned and applied epoxy to one ruby standoff on ETMX, for overnight curing according to the SOS standoff gluing procedure. This included:

  • Removing and reinserting the guiderod until the groove is properly oriented, as seen by microscope
  • finding the right vertical offset with the microscope + 3 axis micrometer stage
  • axial centering by equalizing the distances from the grove to each bevelled edge of the barrel with the microscope stage
  • mixing epoxy
  • Testing the mix by putting some drops on some foil, and putting that in a 200F oven for 15 minutes, and checking that it cured well
  • Applying some tiny droplets of expoxy using the tip of some copper wire, making an effort to keep epoxy away from the glue

Instead of trying to fix up a way of gluing the guiderod with the proper alignment, we chose to be more conservative and glue the standoff today, then switch the gluing fixture's arms tomorrow to glue the guide rod with the good fixture arm. 

Additionally, we chose to glue one of the more assymetric standoffs on this first side. What I mean by this is: We have 3 ruby standoffs with grooves. Two of them have the groove about 1/8th of the way along their length, and one has it about 1/4 of the way. Since the second standoff is going to be glued while suspended, after pitch balancing, we figure that we want to use the more centered groove on that side, meaning we used one of the 1/8th standoffs today.

Unfortunately, we neglected to take any pictures :/

  12294   Tue Jul 12 20:16:15 2016 LydiaUpdateGeneralITMX dust

Looked at ITMX. Johannes and I both saw a fairly large speck of dust near the center of the HR side. We tried to take some photos but couldn't get any with good focus. 

  12295   Tue Jul 12 23:51:16 2016 JohannesUpdateGeneralVent progress - ETMY inspection

On Monday I inspected ETMY, and found nothing really remarkable. There was only little dust on the HR side, and nothing visible in the center. The AR side has some visible dust, nothing too crazy, but some of it near the center.

  12296   Wed Jul 13 00:01:38 2016 JohannesUpdateGeneralITMX dust

We ran out of illuminator juice, and short-term charging couldn't restore enough battery life to continue the work. We should be able to get some better pictures tomorrow.


Looked at ITMX. Johannes and I both saw a fairly large speck of dust near the center of the HR side. We tried to take some photos but couldn't get any with good focus


  12297   Wed Jul 13 00:38:25 2016 JohannesUpdateGeneralVent progress - ETMY attempted repositioning

[Lydia, Johannes]

We attempted to move the ETMY suspension near the access port in preparation for the cleaning process. The plan was to move in the face restraints first to the point of almost making contact, then the ones underneath so the optic is sitting on them, followed by the top one facing down, and then bringing in the stops on the faces.

While moving in the stoppers I noticed that the far lower stopper on the HR side was barely touching the face of the optic in its resting position and was basically pushing it sideways when moved forward. It was just on the edge, so I tried to compensate minimally by moving the underneath stops a little further on the near side, trying to let it 'slide' over a little so the screw would have better contact. I must have been too generous with the adjustment, because while proceeding I noticed at some point that the stick magnets on one side of the optic were not attached anymore but laying inside the OSEMs. The side magnet was also missing, it is now sitting on the suspension jig base plate. The dumbbells all seem intact, but we'll test them before we reglue the magnets to the optic. This is extremely unfortunate, but hopefully won't take too long to fix. At the very least, as Koji put it, the cleaning will be easier with the optic out of the suspension. Still, what a bummer.

  12298   Wed Jul 13 03:16:47 2016 KojiUpdateGeneralITMX dust

Multicolor flash light:

- It seems that the usb port charging doesn't work.

- There is a battery charger on Steve's desk. I set the batteries on it.


White LED flash light:

- I temporarily brought a compatible charger from WB. It's charging two batteries behind the LCD display on my desk.


  12299   Wed Jul 13 15:35:56 2016 LydiaUpdateGeneralVent Progress - ETMY repositioned and removed

[Lydia, Johannes]

Took photos to document the original OSEM orientation and wrote down the serial numbers for each position. We removed the OSEMs, moved the suspension to the accessible side of the table and took out the optic, which was brought to the clean room to have the magnets reglued. The ETMY chamber is now closed up with the OSEMs and clamps inside on the table, and should not need to be reopened until the magnets have been reattached. 

  12300   Wed Jul 13 21:13:51 2016 KojiUpdateGeneralETMX guide rod gluing / ETMY Magnet gluing

[Eric, Koji]

  • ETMX: The Al guide rod has been glued on the mirror.
  • ETMY: The UR, LR, and SD magnets have been glued on the mirror.
  • For both, we are waiting for the glue getting cured.

Handing over message to the next step

  • ETMX: The arm of the fixture has probably been glued together with the guide rod. It has to be taken care when the fixture is removed.
    ETMX gluing section and Attachment 13)

ETMX: guide rod gluing (done) -> fixture unmounting side -> fixture setting -> magnet gluing -> suspend -> pitch balance -> ruby gluing -> air bake
ETMY: magnet (done) -> fixture unmounting -> air bake

ETMY gluing

Mirror transport:
- A transport setup was made with a donut holder for a 3" optic, glass jar, stain less tray, and a CS Stat zipbag. (Attachment 1)

- The magnets have been glued witht the gluing fixture. (Attachment 2)
- We checked the dimensions of the glued magnet and found that the thicker side has to be raised by 1mm. (We used the fact that the relative distance between the wire groove and the magnet is always the same.)
- The ETMs have 2.5deg wedge and this corresponds to 3.2mm height difference between the left and right edges. This meant that the thinner side had to be raised by 4.2mm.
- We used a 0.9mm Teflon sheet for the thicker side (Attachment 3) and two 2.2mm Teflon pieces for the thinner side (Attachment 4). For stabilization of the fixture, two Teflon tubes with a diameter of ~3mm are inserted to the top and bottom side of the mirror (Attachment 5).

Magnet orientation:
- Mirror orientation in the fixture (Attachment 6).
- It was confirmed that existing UR, LR, and Right SD magnets have the polarity of N facing out, S facing out, and N facing out. And we confirmed that this is consistent with ETMX and the procedure document (E970037)
- Along with the procedure document, we arranged the magnet-dumbbells UL, LL, and Left SD magnets to have S-out, N-out, and N-out. (Attachments 7, 8, and 9)

- In prior to gluing, all three dumbbells surfaces were cleaned by acetone and razor blade scrubbing.
- After the epoxy curing test (see below), the three magnet-dumbbell pairs have been glued on the mirror. A single dub of EP30-2 was applied to each dumbbell surface.

- Attachments 10, 11, and 12 shows how glue is spread at each joint.

ETMX gluing

Guide rod positioning:
- The longitudinal position of the guide rod was adjusted using the micrometer microscope such that it located at the center of the mirror thickness.
- The guide rod is not long enough to have the edges sticking out from the form of the fixture arm. Therefore only arm finger of the arm held the guide rod. 
- The height was adjusted to be 1.73mm (68mil) lower than the mirror scribe line. The mirror is fixed on the fixture upside down. So this bonds the guide rod above the scribe line.

- Then the epoxy was applied to the guide rod. The glue was applied to two edges of the rod, but capillary action spread the glue around the rod. It seemed that the fixture and the rod were connected with the glue. Care should be taken when the fixture is going to be removed. (Attachment 13)
- The top side (in the picture) where the stand-off will come is still relatively kept clean. So it must be OK for the stand off. If there is an issue, we can shave the epoxy with a razor blade.

Glue testing

- EP30-2 tends to fail to get cured. In order to check the mixture is properly made or not, we put a test piece into air bake oven.
- The procedure says, 200F 15min bake show if the glue is in a good shape or not.

- We have the temperature sensor setup on a air bake oven, but it seemed that the indicated temperature there is overestimate.
  The heating setting of 2 was enough to show the temp of 100degC although EP30-2 didn't get cured with this setting.

- Our experience says that heater setting of "5" makes the temperature ~90degC. On July 12nd, this setting showed the temp of 90degC. Today (July 13rd) it didn't. In the both cases, the epoxy got cured nicely. So we should use this setting.

  12301   Thu Jul 14 01:00:33 2016 KojiUpdateGeneralETMX ruby guided gluing

Today I took the picture of the glued ruby stand-off. The groove has not been invaded by the epoxy!

  12302   Thu Jul 14 22:29:57 2016 ericq UpdateGeneralETMX guide rod gluing / ETMY Magnet gluing

The pickle puckers came off ETMY cleanly yes ETMY now rests in the ring holder, under a glass jar, with all of its magnets.

We removed the guiderod gluing fixture from ETMX without any apparent damage to the fixture arm, optic, or guiderod epoxy joint. 

I started measuring some distances on the optic for the side magnet gluing, but am not sure of it yet. So, I didn't manage to start the gluing today. 

  12305   Fri Jul 15 16:23:51 2016 ericq UpdateGeneralGluing setbacks

[ericq, Lydia]

Here is a picture of the ETMX guide rod post-gluing. There is unfortunately a fair amount of excess. The "tab" is the result from the epoxy travelling along the finger of the fixture arm that held the guide rod.

We set out to glue the previously remove ETMX side magnet, and set up the fixture to do so. For ETMX we needed 3 mm of shimming on the thick side, and 6mm on the thin side.

However, while cleaning the magnet+dumbbell base of epoxy residue, I broke the dumbbell off of the magnet no

We then fetched the spare side magnet that Steve had been holding onto. While cleaning it, it was dropped and dissapeared from this plane of existence nono

So, instead of gluing a side magnet today, we are gluing the existing magnet and dumbbell back together:

Sadly, this used up the last of our EP30.nonono

Though Koji had the foresight to order more(yes), it will not arrive until Monday/Tuesday, so no side magnet gluing until then.frown

  12306   Fri Jul 15 17:44:37 2016 AakashSummaryGeneralAcromag Setup | SURF2016

Aidan has described the physical connections and initial setup here :  https://nodus.ligo.caltech.edu:30889/ATFWiki/doku.php?id=main:resources:computing:acromag#recovering_from_a_terminal_power_communication_outage  .

Since I used a Raspberry Pi(domenica.martian) for communicating to Acromag(acroey.martian) card, I had to recompile everything for linux-arm architecture. 

For EPICS installation, download the EPICS base from http://www.aps.anl.gov/epics/download/base/baseR3.14.12.3.tar.gz . Installing dependencies, build, install epics at /usr/local/epics. By downloading modbusApp source from https://llocds.ligo-la.caltech.edu/daq/software/source/epics-  , build the modbusApp for linux-arm architecture in modules/modbus directory inside epics base.

Put all the files mentioned by Aidan and run a tmux session to grab channels.

Also, pyModbus can be used to read the channels. I'll put the physical connections schematic shortly.

  12308   Mon Jul 18 05:05:05 2016 AakashUpdateGeneralHeater for Seismometer Enclosure | SURF 2016

I took off the silicon rubber heaters which were used by a SURF last year for heating the enclosure. The heater data sheet has mentioned the power dentsities, but I doubted the values. So I wanted to measure the actual power density by these heaters. I think the rubber heaters are broken somewhere within, the surface is not heated evenly. Although I don't have a good quantative reason to use, I was thinking to use a thermoelectric cooling module for the enclosure. 

From the data I collected few days back, I am trying to obtain a transfer function of temperature inside the enclosure to that of outside. My aim is to measure the pole frequency of temperature fluctuations inside the enclosure relative to the outside fluctuations.


  12310   Tue Jul 19 13:21:42 2016 JohannesUpdateGeneralVent progress - ETMY attempted repositioning

[Lydia, Johannes]

We moved ITMY from its original position to a place near the access point. We took the OSEMs off first, and noticed that the short flat head screw driver was still a little too long to properly reach the set screws for the lower OSEMs. We were able to gradually loosen them, though and thus remove the lower OSEMs as well. We had to move a cable tower out of the way, but used clamps to mark its position. After making sure the optic is held by its earthquake stops, we moved it to its cleaning location. All magnets are still attached.

  12312   Tue Jul 19 15:30:08 2016 SteveUpdateGeneralHEPA dryer and dust

I set up a simple HEPA filter dryer to dry your clean room garment before  you can put it away into your storage box.

Our lab is dusty ! This is  specially important when we are vented. Please wipe things daily and cover item with foils .... etc.

  12313   Tue Jul 19 16:39:29 2016 LydiaUpdateGeneralETMX magnet gluing/guiderod excess glue removed

[ericq, Lydia]

The epoxy arrived. Eric managed to remove the excess glue below the guiderod with a razor blade (see attachment 1). The magnet and dumbell that came apart were reglued successfully and passed the stregth test of picking up the magnet from the table by the dumbell, so the magnet was glued back on the optic and is setting in the gluing apparatus (see attachment 2).

We double checked the polarity against the side magnets on ETMY. Because of the gluing position strategy (a fixed distance toward the HR side from the groove location), the other side magnet appears slightly below the center of the gluing barrel, which after some discussion with Koji was determined to be ok. 

  12317   Thu Jul 21 05:22:26 2016 AakashUpdateGeneralTemperature measurements across the enclosure | SURF 2016

I have measured the transfer function of temperature fluctuations inside the enclosure to that of the temperature fluctuations outside. The transfer function has been estimated by using 'tfestimate' which is library function in Matlab and which estimates the transfer function based on Welch's method. The attached plots shows the transfer function of the temperature inside the enclosure to that of outside temperature.



In order to determine a relation between temperature inside the enclosure to that of the outside temperature, I have calculated the mean squared coherence.  I have used Matlab's 'mscohere' library function which uses Welch's method to calculate the coherence. Attached plot shows the coherence between the temperature across the enclosure.


Also, I have attached the matlab script which I used for generating these plots.


  12322   Thu Jul 21 17:01:59 2016 ericqUpdateGeneralETMX magnet gluing/guiderod excess glue removed

One step forward, two steps back...

While attempting to suspend ETMX, I broke off a side magnet crying

It is now gluing

(This is *not* the one that was previously glued. I.e., now both ETMX side magnets have been reglued)

  12323   Thu Jul 21 21:38:44 2016 AakashUpdateGeneralTemperature measurements across the enclosure | SURF 2016

I have made the changes as suggested by Gautam.

  12326   Fri Jul 22 05:20:26 2016 AakashUpdateGeneralTemperature measurements across the enclosure | SURF 2016

Please find the new attached plots and the new script.

  12327   Fri Jul 22 23:03:23 2016 gautamUpdateGeneralETMX suspension - progress

[ericq, gautam]


Today, we attempted to progress as far as we could towards getting the mirror suspended and gluing the second wire standoff. We think we have a workable setup now. At this stage, the suspension wire has been looped around the magnet, the second wire standoff has been inserted, coarse pitch balancing has been done, and we have verified that side OSEM/magnet positioning is tenable. Details below.


  1. First we verified that the epoxy on the side magnet re-glued yesterday had dried (verified using control setup of epoxy in aluminum foil + copper wire - we didn't perform any further tests like pulling the magnet off the tabletop as we were satisfied)
  2. We placed the optic inside the suspension cage, resting on the 4 lower earthquake stops.
  3. We looped the suspension wire around the optic. This is a somewhat challenging procedure. After consulting the documentation, we decided to follow the given advice and loop the wire around from the bottom of the optic, one side at a time. It is tricky to thread the wire between the two lower earthquake stops and get it up around the side. The side magnets were an unexpected ally in this effort as they served as some sort of intermediate checkpoint from which we could pull the wire further up. We then lightly clamped it to the winches mounted atop the suspension cage.
  4. After verifying that we had routed the wire correctly through the various stages (primary and secondary suspension points at the top of the cage), we placed the wire under very slight tension by had, and then tightly clamped the wires in the winches (we then cut off the excess length).
  5. In this state, we proceeded to install the second wire standoff (having verified that the wire was indeed sitting in the groove on the other side). 
  6. We then proceeded to raise the optic to the desired height (center of optic to 5.5 inches above the table top) with the help of the microscope and the lines on the barrel side. 
  7. Next, we attempted to freely suspend the optic (i.e. no contact with the viton tips). We were initially unsuccessful but Eric did some fine adjustment of the (unglued) standoff to achieve a stable configuration. However, the wire is now really close to the magnet - although it is not clear to me if it is touching the magnet as we initially suspected - see Attachment #1, it may be that if the wire is touching something, it is the dumbbell and not the magnet itself. While this is clearly not ideal, we think that this setup is workable as is. If after doing the pitch balancing, if the deviation of the wire becomes much more pronounced, we may have to re-glue the side magnet. In any case, both the horizontal scribed lines are now 5.5 inches above the table top.
  8. We then brought over the OSEMs from the ETMX vacuum chamber to the cleanroom. As a first check, we wanted to ensure that one of the side magnets could accommodate an OSEM (because both side magnets have been re-attached after the optic was removed from the old suspension). Attachment #2 suggests that this is possible, even though the relative positions of the side magnet and the shadow sensor may be sub-optimal. We will only really know after hooking up the electronics.


  1. We found that after a few hours, there was some sag introduced in the wire, presumably it stretched into an equilibrium position under the weight of the optic. We will re-check the heights tomorrow while conducting further tests.

Immediate to-do:

  1. Insert all OSEMS. Ensure that the magnet positions relative to the coil are compatible.
  2. Enable damping loops. We have a cable coming from the IFO area into the cleanroom through a hole-in-the-wall. We are missing a DB25 gender changer at the moment. 
  3. Do the pitch balancing.
  4. Glue the second standoff in place. 

Other attachments:

Attachment #3 - Unglued stand off with wire in the groove, mirror freely suspended.

Attachment #4 - Glued stand off with wire in the groove, mirror freely suspended. Clearance between wire and magnet looks reasonable.

Attachment #5 - Barrel of optic (underside), mirror freely suspended. The wire seems to be in a reasonable orientation along the barrel, albeit not perfectly parallel.

Koji just pointed out that we should check that the unglued ruby standoff is in good contact with the barrel of the optic. Attachment #1 suggests that maybe this is not the case. If you zoom into Attachment #1, it is not clear if the standoff is sitting on the glue.

  12328   Sun Jul 24 03:43:56 2016 ericqUpdateGeneralMagnet positioning

When Koji and I were gluing magnets to ETMY, we decided to position the side magnet based on the empirically observed offsets from the standoff groove seen at other side magnet locations. Specifically, we figured that the magnet should be glued 1.25mm closer to the HR surface than the wire groove.

However, Steve has told me that he believed that this distance should be something like 0.5mm. 

I used the 1.25mm figure when gluing the ETMX side magnets, which now do not align well to their OSEM mounts. While it is certainly possible that I made an error when shimming the fixture, I think it is also possible that this figure was incorrect. 

Sadly, after poring through the DCC and various elogs, I have not been able to come up with a definitive answer on what this offset should actually be.

One approach is to examine the suspension tower dimensions. I.e. when subject only to gravity, the wire loop should lie in the plane of the back face of the top block of the suspension, as it is constrained by the clamps. Thus, the standoff grooves also lie in this plane. The center of the side OSEM mounting holes are about 1.64mm in front of this plane, which is larger than the 1.25mm figure that Koji and I came up with. Examining the picture Gautam posted of the marginal magnet/OSEM alignement, we see that this figure would in fact move the magnet in the wrong direction...

ELOGs in which the intitial side magnet gluing and fixture shimming are detailed do not reference the absolute position of the side magnet, nor do they include any pictures of their fixture setup. (Some links for the curious: 2652 2654 2668)

The DCC isn't much help either, as it is not clear what version of the gluing fixture we actually have. There is a drawing for a 40m specific version, but it includes swappable side-magnet-pickle-picker-slots to achieve different positions for different (circa 2001) optics; this is not the kind of fixture we currently have in our possesion. (https://dcc.ligo.org/D010131) I have discovered that some versions of this fixture (https://dcc.ligo.org/d990168) include an assumed 0.5deg wedge angle and thus position the two side slots differently. Although the fixture we have has no identifying marks on it whatsoever (naturally), I measured the two side slots to be different in axial position by roughly 0.6mm, which is consistent with a 0.5deg wedge. Furthermore, the sign of this difference indicates that this fixture ring is designed for the opposite wedge orientation than our ETMs, which have a 2.5deg wedge, making this fixture wrong by 3deg (which is ~4mm over the diameter of the optic). 

We did not account for this for either ETMX or ETMY, so this is another source of error, but this does not give us much guidance on what the real absolute magnet position should be.

  12331   Mon Jul 25 13:01:49 2016 ericqUpdateGeneralETMX suspension - progress

(Full resolution versions of the photos in this ELOG are on picasa)

The OSEM gender changers were not in the box labelled as such, we need these to be able to use the OSEMS to see just how bad the side magnet alignment is, and to do any kind of damping for the fine pitch balancing. The hunt is on.

In the meantime, Gautam and I checked out the standoff seating, and alignment of the face OSEMS (after slightly adjusting the wire length - I guess some sagging is still happening).

With a bit of poking, we convinced ourselves that we sat the standoff in contact with the optic's barrel. Amazingly, we were able to maintain the coarse pitch balance of the optic.

We then partially inserted the face OSEMS, to check their magnet alignment. ("partially" means that the OSEM is not actually enclosing the magnet, we don't want to knock anything off) They seem ok, but not perfect. These magnets were not removed or reglued, so presumably their alignments should be unchanged.

  12332   Mon Jul 25 13:47:19 2016 ranaUpdateGeneralETMX suspension - progress

Ugh. frown

Steve, please look into getting some plated magnets (either SmCo or NdFeB is OK) of this size so that we can install cleaner magnets by the next vent.

  12335   Mon Jul 25 20:37:46 2016 gautamUpdateGeneralETMX suspension - Side OSEM test

[Lydia, gautam]

Summary: We did some preliminary tests to check if at least one of the side magnet positions is usable for the side OSEM. We mainly wanted to check how much dynamic range we lose because of the sub-optimal longitudinal positioning of the side magnet. We found that when the side magnet was mainly moving along the axis of the side OSEM (with minimal yaw motion as gauged by eye), the PD voltage bottomed out at ~80 counts (while the completely unoccluded readout was ~800 counts). 


  1. First, we placed the face OSEMs into their holders one by one, and adjusted their position till the readout was approximately half the saturation value (as judged by the average value of the readout, at this point, the mirror was still swinging around a fair bit).
  2. Next, we enabled the POS, PIT and YAW damping (with all existing settings unchanged), but with the SD coil input and output disabled. We had to increase the watchdog threshold to ~600mV.
  3. Once the optic was reasonably well damped (~70mV on the watchdog was the best we saw), I put in the side OSEM till the PD was completely occluded. At this point, I enganed the earthquake stops, and then released the mirror such that it was freely hanging. I then observed the optic by eye, and noted a time when the dominant motion was along the axis of the side OSEM coil (i.e. minimal YAW motion). 
  4. Attachment #1 shows time series plots of the 5 OSEM PD voltage monitors. Perhaps because the side OSEM input was disabled, the damping wasn't as efficient as it normally is (also there is a fan blowing air around the clean bench). But at the point indicated on the plot, the YAW motion was negligible to the eye, while the dominant motion was along the axis of the coil. During this time, the readout bottomed out at approximately 10% of the saturation value (towards the end of these plots, I disabled the damping loops and began pulling the OSEMs out one by one). Because the damping was imperfect, this is only an approximate guess of how much dynamic range we are losing. But does this warrant regluing the side magnet?

Other remarks:

  • The 4 face magents were reasonably well centered in the coil. While Eric and I were looking at this earlier today, the LL magnet looked a little close to the coil, but after putting all 4 OSEMs in, the situation looked reasonable to the eye. I couldn't take pictures because of space constraints, and furthermore, it's almost impossible to hold the camera in the correct vertical position. 
  • Steve, Eric and I couldn't find the OSEM gender changer anywhere in the lab and it wasn't in the box it was advertised to be in. So we made a custom cheater cable, and cleaned it by wiping with Isoprop., and wrapped it in foil for use in this test. The OSEM pins should probably be cleaned before we put these back in vacuum. 
  12340   Tue Jul 26 18:07:57 2016 gautamUpdateGeneralETMX suspension - Further OSEM Tests

Today, we did the following:

  • Once again, inserted all four face OSEMs till the sensor voltage readouts were approximately half their saturation value. The presence of some ferromagnetic material in the Honeywell components makes this tricky as each coil is coupled to the other three, but we were able to converge to a point where all the voltage readouts were oscillating around a mean value of ~40-60% of their maximum value, with all the damping loops OFF.
  • Turned on all damping loops, and verified that the OSEM positioning was indeed such that the sensor readout is nominally around 50% of the saturation value. The air buffeting around the clean bench means that the damping isn't nearly as effective as it is inside the vacuum chamber.
  • Attempted to increase the gain on the damping loops - we first switched out the Chebyshev low-pass filter in all the damping loops for something a little less aggressive, to allow us to turn up the gain. However, this experiment wasn't a success, when we turned the damping loops on, they were ringing the optic up.
  • At this point, Eric checked the offset sliders (summed in via the slow system) and saw that they were not zero. We zeroed these, but naturally, they destroyed the OSEM positioning equilibrium we had established earlier. So we had to go back and re-position the OSEMs
  • After re-centering the face OSEM magnets relative to the LED-PD pair, we insertd the side OSEM such that the side magnet completely occluded the PD. Interestingly, Eric noticed that the magnetic attraction between OSEM and magnets conspired to center the side magnet fairly well in the side OSEM, when it completely blocked the PD. However, when he returned the side OSEM coil to its nominal operating position of approximately half-blocking the PD, some minor misalignment was re-introduced (i.e. even when the optic was swinging mostly along the axis of the side OSEM, the voltage readout did not quite go down to 0). 
  • We then decided to compare the spectra for the error signals for the 4 DOFs with the current configuration (i.e. suspension clamped down to table top, optic freely hanging, all OSEMs reasonably well centered, and with the ETMX SUS model reverted to its normal state) to some reference (see Attachment #1). I initially thought I would wait for the optic to settle down a bit more before taking the spectra, but it doesn't seem to be showing any signs of getting any quieter in the last one hour. In Attachment #1, I have plotted as reference the spectra of the error signals from the early hours of 4 July 2016, at which point we were at atmosphere but the heavy doors were not yet off, so this is not really a fair comparison, but we don't really have a period in which the optic was exposed to the atmosphere and with the OSEMs in place, at least from this vent. Colors are identical for a given DOF, with todays trace as a solid line, and the reference dashed.
  • We did not check the room available to install some shimming piece of metal in the side OSEM holder, as a possible solution to solve the misalignment problem. Steve has already found pieces of varying thickness, and they are soaking in acetone right now, we plan to air bake them tomorrow. 

I will have another look at the spectra tomorrow morning, to see if the damping improves overnight. 

  12345   Thu Jul 28 03:22:28 2016 ericqUpdateGeneralETMX magnets re-reglued

[gautam, ericq]

Brief summary, some pictures and such follow in the daytime. 

  • All magnets enclosed by OSEMS were knocked off. (This means one side magnet remained, on the guiderod side)
  • Glue residue cleaned from ETMX
  • Dumbbell feet were cleaned of glue, finely sanded, re-scored with a razor blade
  • The magnet gluing fixture was painstakingly aligned multiple times, adjusting the shim height to get a magnet/wire groove clearance of 0.25-5mm
  • Epoxy mixed, test batch cured perfectly, applied to 5 dumbbells (after triple-checking polarities) and set to glue. 

The epoxy needs at least 12 hours of room temperature air curing, so no touchy until 3:30PM on Jul 28!

  12347   Thu Jul 28 13:49:44 2016 gautamUpdateGeneralETMX magnets re-reglued

[gautam, ericq]

Brief summary, some pictures and such follow in the daytime. 

  • All magnets enclosed by OSEMS were knocked off. (This means one side magnet remained, on the guiderod side)
  • Glue residue cleaned from ETMX
  • Dumbbell feet were cleaned of glue, finely sanded, re-scored with a razor blade
  • The magnet gluing fixture was painstakingly aligned multiple times, adjusting the shim height to get a magnet/wire groove clearance of 0.25-5mm
  • Epoxy mixed, test batch cured perfectly, applied to 5 dumbbells (after triple-checking polarities) and set to glue. 

The epoxy needs at least 12 hours of room temperature air curing, so no touchy until 3:30PM on Jul 28!

Attachment #1 - After multiple trials shimming the magnet gluing rig with teflon spacers, we think that we managed to find a configuration in which the side magnet edge is between 0.25 mm and 0.5 mm from the groove in the ruby wire standoff in which the wire will sit. 

Attachment #2 - Zoomed in view of the side magnet.

Of course we won't know until we suspend the optic, but we believe that we have mitigated the misalignment between the side OSEM axis and side magnet.

The short term plan is to try and suspend ETMY in the end chamber and have a look at the alignment between all magnets and OSEM coils for it. Once the epoxy on ETMX is cured, we will try and suspend the optic again, this time taking extra care while tightening the wire clamps.

Unrelated to this work: Bob just informed me that we had left the air bake oven on overnight - this unfortunately melted the plastic thermocouple inside.

  12348   Thu Jul 28 16:43:01 2016 LydiaUpdateGeneralETMX aluminium standoff groove condition


I took some pictures with the digital microscope of the aluminum standoffs removed from ETMX. The first one had some leftover epoxy still attached, so I was able to distinguish which part of the groove was occupied by the wire. A better microscope would help (this one has a maximum magification of 80, 200 or so would be much better) but I was still able to see what looks like a second minimum inside the groove at the wire location (see Attachments 1 and 2). The bottom edge of the standoff shows the profile of the groove on the opposite side from the glue. I took several photos with different lighting angles and at different locations on the microscope stage and convinced myself that this was not just an artificial effect. I also took photos of the groove in a different place and did not see this feature (Attachment 3).

The other standoff in the same container had no visible damage to the groove or to the body of the rod. I rotated it under the mocroscope and could celarly see the 'V' shape all the way around. The smooth undanaged groove caught the light more easily and was obvious. The damaged one is scratched around much of the surface, but the undamaged standoff is very smooth. Eric, were both aluminum standoffs in the container with the extra ruby one taken off ETMX, or was one of them new? in any case, see Attachement 4 for a comparison. The believed damage is somewhat visible on the top edge of the lower standoff in the photo. 

[Edit:] Also, in the drawings it looks like the specified radius for the bottom of the groove (0.001 in) is smaller than the radius of the wire (0.00085 in). This would prevent having two clean points of contact like Steve and Gautam were describing as the goal. This is also true of drawings for the new Sapphire guiderods, though the dimensions are in metric units the specified radius of the groove bottom is smaller than the wire's diameter, but larger than its radius. Maybe this providied the initial ability for the wire to move around and carve two distinct grooves. 

  12349   Thu Jul 28 17:48:17 2016 gautamUpdateGeneralETMY LR magnet broke off

While ETMX magnets were curing, I wanted to try and suspend ETMY in the endchamber, put in the OSEMS and see if the magnets aligned well with the coils, and run the same type of diagnostics we have been doing for ETMX. However, while I was trying to slip the optic into the wire, the UL magnet on ETMY broke off. I recovered the magnet and now both optic and magnet are back in the cleanroom. The magnet dumbbell has been cleaned with acetone and then sandpaper to remove residual epoxy - it remains to clean the residue off the optic itself before re-gluing the magnet tonight

I also noticed that the existing wire in the suspension had a kink in it. It looks fairly sharp, and I think we should change the wire while re-inserting the optic. Putting the optic into an existing loop of wire is tricky, as if you go in from the front of the suspension cage, the magnets on the AR side attract the wire, and makes it quite difficult to loop the wire around. I have to think of some way of holding the wires in place while the optic is being placed, and then, once the optic is roughly in position, slip the wire into the grooves in the standoffs. 

I took the opportunity to replace the face OSEM coil holder screws while the chamber was open. 

EDIT 9 August 2016: It was in fact the LR magnet that was knocked off.

  12350   Thu Jul 28 22:43:03 2016 ranaUpdateGeneralETMY UL magnet broke off

I'd recommend replacing the wire and grinding down the clamp to prevent cutting the wire. Since we have almost never replaced clamps, many of them probably have grooves from the wires and can make unpleasant cuts. Better safe than sorry in this case.

  12351   Fri Jul 29 03:32:30 2016 ericqUpdateGeneralETMX suspended once more

[gautam, ericq]

Tonight's progress on ETMX:

  • All pickle pickers removed successfully, face magnet positions look symmetric (all on border of AR coating), side magnet same location as in yesterday's photo
  • Flipped around clamp blocks on winches and top blocks, refinished main clamp block not on tower yet
  • Trimmed viton tips of EQ stops, I had left them too long before, leading to bending and unwanted translation when in contact with optic
  • Inserted optic into bottom EQ stops, turned bolts to position optic at correct height and sort of pitch leveled
  • Threaded new length of wire up through both sides, clamped at winch. Made an effort to avoid any wire twisting. 
  • Winched until enough tension to sit in standoff groove, inserted second ruby standoff
  • Winched to just come up off of bottom EQ stops, observed neccesary correction of second standoff for rough pitch balance
  • Roughly pitch balanced by iterating standoff location
  • Partially inserted OSEMS, all four face magnets looked low. We figure it's more likely that our microscope was set to the wrong height, than all four OSEMS being too high by the same amount. (Given how the face magnets are all located on the concentric circle of the AR coating, we know there wasn't much translation error in the magnet gluing)
  • Did some common mode winching of both wire ends to get magnets to correct height, all OSEM alignments look good
  • Inserted OSEMs to half of open voltage
  • Having trouble engaging stable damping of all DoFs, this will be followed up in the daytime.

Since the air bake oven we had been using is out of commision, we're not sure where to do our EP30 test runs. If we are fortunate, we can get the fine pitch balance done tomorrow while Bob is still around, so he can help us quickly bake the test dots, so we can do the standoff gluing. 

  12354   Fri Jul 29 13:17:34 2016 KojiUpdateGeneralOven

While the air bake oven situation is being improved, how about to buy a cheepo toaster oven at Target, BestBuy, or anywhere?

We don't need precise temp control for the glue cure test. At LLO I saw that they are using cooking grade oven for this purpose.
(Of course, we should not use this oven for foods once it is used for epoxy)

I have a fryer temp sensor in my office on the freezer stole from the 40m long time ago. You should be able to measure high temp.

If you have such an oven, I'd love to borrow it for the OMC lab later, as I expect to work on epoxy bonding later.

  12358   Sun Jul 31 17:28:38 2016 ranaOmnistructureGeneralupclean

I cleaned up the south Electronics bench today.

The other two, as well as several of the desks are in some chaotic state of degradationno. Please clean up your areas and put away projects which do not need to remain staged for several months. Try to eliminate "that's not mine" and "I don't know who's that is" from your vocabulary.  angry Fight back against entropy!

  12360   Mon Aug 1 18:50:29 2016 AakashUpdateGeneralAcromag Setup | SURF2016

There were many unknown and unsolved problems with using modbusApp for linux-arm architecture. So I tried to install the necessary files to setup Acromag Busworks card 1221-000 on Zita(, which is a linux-x86_64 machine on the martian network. After installing a few dependencies and seting up few symbolic links for some libraries, everything is successfully configured. Initially I was unable to run myiocconfig.cmd file(as mentioned by Aiden on ATF wiki page) due to a undefined macro error for envset. Later I found that this error might be due to THIS bug in epics base. So, I removed the first four lines of that given code and directly referenced the .db file's location and it worked.

Now, I am facing another issue while running this file but on different line. Random symbols are returned on the last second line of the file each time I run it. I have attached the screenshots of those errors. I tried changing the encoding of the file several times but still it is showing the same error.


  12364   Wed Aug 3 10:52:03 2016 SteveUpdateGeneralETMY soaking dish

ETMY UL epoxy soaking dish. All teflon in glass.


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