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ID Date Author Type Categoryup Subject
  3281   Fri Jul 23 18:55:25 2010 kiwamuUpdateSUSPRM and TT installed

I updated the last entry.

  3294   Mon Jul 26 20:12:18 2010 kiwamuUpdateSUSOSEMs on PRM

 [Alberto and Kiwamu]

We installed the OSEMs to the new PRM.

As I wrote down on the elog (see here)  today's mission was to install the OSEMs to the PRM.

After putting them on the tower we adjusted the readout offsets by sliding the OSEMs so that they can stay in the linear sensing ranges. 

Now all of the OSEMs have almost good separation distances from the PRM.

In the attached picture you can see the OSEMs installed on the PRM tower ( middle: PRM tower, left: BS tower)


(what we did)

 1. moved the PRM tower close to the door so that we could easily access the PRM.

 2. leveled the table by putting some weights and confirmed the level by a  bubble level tool.

     - We must level the table every time when we set / adjust any OSEMs,  otherwise the readout voltages of  the OSEMs vary every time due to the tilted table.

 3. released the PRM by loosing the earthquake stops

 4. put the OSEMs with approximately right separation distances from the PRM.

      -  At this phase we can see the readout of the OSEMs, which were oscillating freely because we still didn't enable the damping.

        -  The OSEM positions were checked by looking at useful notes on the wiki (see here).

 5. turned on the damping servo of the OSEMs

       - Without changing any gains, it worked well. 

      - Then we could see stable readouts of the OSEMs which didn't show any oscillations in turn because of the damping.

 6. checked the level of the table again

 7. set each of the OSEM readouts to the half of its maximum value by sliding their positions slightly.

      - The readout offsets were at almost the half value within +/- 100 mV accuracy (this was the best accuracy we could adjust by our hands)

 8. screwed down the earthquake stops to lock the PRM.

      - Now the damping is off.

 9. closed the door

 


(to be done)

 *  Putting the PRM tower back to the designed place

 *  Installation of the pick off mirror

 *  Arrangement of the PZT mirror

Attachment 1: DSC_2279.JPG
DSC_2279.JPG
  3295   Mon Jul 26 20:30:35 2010 JenneUpdateSUS2 Tip Tilts suspended and balanced

[Koji, Jenne]

We were on Team Cleanroom, while Kiwamu and Alberto were on Team Chamber.  Team Cleanroom suspended and balanced 2 Tip Tilts this afternoon.

One of the TTs that was suspended today is the one which was broken on Friday (see elog 3278).  We resuspended it using the regular 0.0036" diameter wire (91um).  We balanced it using the HeNe oplev, and then set it aside.  This TT has serial number 2.

We noticed that, like the previous 2 TT suspensions (this one before it was broken, and the one actually installed in the BS chamber on Friday, which is #3), there seems to be a little bit of hysteresis in the pointing.  The difference comes if we poke the top of the mirror holder and observe the place the reflected beam spot comes to rest at, and if we poke the bottom of the mirror holder.  The beam spot stays a little higher when we poke the top vs. when we poke the bottom. 

To combat this, we tried suspending our second TT of the day (the one that Kyung Ha and I had half finished) using thinner wire for the mirror holder.  We used the 0.0017" diameter wire (43um) that is used for the SOSes.  Unfortunately, it still seems like there is a similar hysteresis.  The thin-wire TT has serial number 4.

While working on TT4, we recalled that we have to include rubber dampers for the vertical blade springs.  Oooops!  We used some of the leftover #4-40 screws with viton tips that Zach and Mott had made for Earthquake stops to damp the vertical resonance of the blades.  We measured the Q factor by flicking the blades up or down.  We changed the oplev setup to be a shadow sensor setup, and watched the ringdown of the vertical mode on the 'scope.  We counted #cycles/time = frequency, and the t(1/2) time for the exponential ringdown to calculate the Q.  For the shadow sensor, we positioned the QPD in line with the initial HeNe beam, and placed the edge of the mirror holder clamp partially in the beam, so the beam was partly occluded.  When the mirror shook up and down, more or less of the beam was blocked, and we could see this power fluctuation on the 'scope.

Using the formula Q = pi  f0 T1/2 / ln(2) = 4.53 f0 T1/2, where T1/2 is the the time it takes for the amplitude to decay by half, we measured a Q of 31 for the vertical mode with no damping, and a Q of 14 with damping.  Koji confirmed the calculation and put it into wiki.

We need to go through the other TTs that have been assembled and give them their rubber dampers.

 

  3302   Tue Jul 27 21:38:21 2010 kiwamuUpdateSUSinstallation of in-vac optics

[Alberto and Kiwamu] 

We put the PRM back approximately on the right place.

Also we installed the pick off mirrors and the PZT mirror.

Since the main beam after the MMT still has not been well aligned , we put those optics approximately on the right place. A fine alignment of those will be performed later

The offsets of the PRM OSEMs are still kind of okay.

The next things we have to do are

(1) installation of a tip-tilt for the SRC, (2) alignement of those optics by using the main laser and (3) installation of the green optics.

 


what we did

 1. put the PRM back to the designed place.

     - After this, we released the PRM from the earthquake stops and turned on the damping servo.

      - Now the earthquake stops are at a distance of approximately 1mm from the PRM. These separation distances were tuned by counting the turn number when we screwed them off.

 2. leveled the table

 3. adjusted the separation distances from the PRM to the OSEMs.

    - The table below summarize the current OSEM offsets. LL may still need to be adjusted.

  Max./2 [V]

measured offsets [V] 

after adjustment 

discrepancy [%]
UL 0.874 0.928 + 6.2 %
UR 0.848 0.777 - 8.4 %
LL 1.038 0.796 - 23 %
LR 0.967 0.845 -12 %
SD 0.840 0.745 - 11%

 4. put the PZT mirror on the right place.

      -  This PZT mirror is going to be used for beam steering after the MMT.

 5. put the pick off mirror and its associated optics.

     -  This pick off mirror provides with the beam eventually going to IP_ANG and IP_POS.

 


current status

The table below shows the current status of the installed optics.

Red letters represent the incomplete states which still need further adjustment.

Blue letters represent the complete status which don't need any further adjustment.

 

name on the drawing

(see the wiki ) 

status
BS tower BS well aligned by a caliper
PRM tower PRM approximately aligned. LL OSEM
TIp-TIlt PR3 approximately aligned
Pick off Window (wedged) IPPO

wedge is correctly set (fat part is on the left).

 approximately aligned

steering mirror IPPOSSM1 mirror is correctly flipped. approximately aligned
steering mirror IPANGSM1 mirror is correctly flipped. approximately aligned
steering mirror IPANGSM2 approximately aligned
pzt mirror SM2 approximately aligned

 

Attachment 1: DSC_2284.JPG
DSC_2284.JPG
Attachment 2: DSC_2291.JPG
DSC_2291.JPG
  3303   Tue Jul 27 23:46:45 2010 JenneUpdateSUSQ measurements of 2 TTs

[Koji, Jenne]

We took measurements of the Q of all the modes that we could think of for TT#4, and then repeated several of the same measurements for TT#2.  We noticed that when we took off the backplane and then replaced it on TT#4, the pitch pointing had changed, so we had to repeat the balancing procedure by slightly shifting the position of the wire clamps relative to the mirror holder. No fun. We decided to quit removing the backplanes. 

The main conclusion of this evening's measurements of TT#4 is that everything looks very close to the design ideas.  Good work team!

TT#4:

'Free Swinging' values (just for interest)

Vert, no damping:   Q = 31.4

Pitch, no damping (ECD backplane removed): Q = ~700

Yaw, no ECDs: Q = ~900

Pos, no ECDs (no measurement) - we had already put the backplane back on, and didn't want to take it off again.

 

Damped Values:

Vert, with damping: Q = 14.3

Pitch, with ECDs: overdamped, so Q < 1/2

Yaw, with ECDs: Q = 2.3

Pos, with ECDs: Q = 1.4

Side, with ECDs: Q = 1.9

 

We also measured the resonant frequency of each of the ECDs for this TT (since we had the backplane removed anyway...)

ECD UL: 10.05Hz

ECD UR: 10.15Hz

ECD LL: 10.21Hz

ECD LR: 10.21Hz

 

TT#2:

Yaw, with ECDs: Q = 7.0

Pitch, with ECDs: overdamped, so Q < 1/2

Vert: Problematic.  No damping, f = 25.9Hz, Q = 36.  With rubber dampers, f = 20.0Hz, Q = 42.   Yes, you read that right.  The frequency is lower, and the Q is higher *with* the damping.  Perhaps our brains are fried.  Perhaps we've discovered new, inconsistent physics (awfully unlikely....). We'll revisit this again tomorrow to figure out what mistake we're making.

  3313   Wed Jul 28 17:32:37 2010 kiwamuUpdateSUSinstallation of in-vac optics

[Jenne, Koji and Kiwamu]

We have installed two steering mirrors and the green periscope.

Also we took the tip-tilt out from the chamber for characterization.


1. installed two steering mirrors

     - We installed IPPOSSM2 and IPPOSSM3.

    - Because IPPOSSM2 is a new 0 deg mirror so we newly engraved "Y1-LW1-2037-1064-0-AR" on the mount and deleted  the previous enegravement.

      For the 0 deg mirror itself, it had already been engraved by Koji. The wedge was horizontally aligned.

      Now IPPOSSM2 is off from the right place by 5 inch for convenience because it may touch our stomachs when we try to lean further into the chamber.

    - IPPOSSM3 is a 45 deg mirror which used to be in the chamber and had been already correctly engraved, so we didn't have to newly engrave on it. Now it's on the right place approximately.

 2. put three oplev mirrors

      - Two of them are approximately on the place, but one which is going to be on the center of the table is not on the place because there is a cable distributer sitting exactly there.

 3. installed the green periscope

      - Both the mirrors and the periscope were correctly engraved.

     - Now it's sitting on the right place approximately.

 4. removed the tip-tilt 

      -  This tip-tilt is now in the clean room and the mechanical mode will be characterized. 

 


 The next things to be done

* Cross-coupling evaluation of the PRM OSEMs

* Rearrangement of the cable distributer panel.

   - In order to do this we have to pull its cables which are attached to the stack.

* Installation of three green steering mirrors

   - All of them need to be engraved.

* Installation of two tip-tilt

  - One for the SRC and the other for the PRC

  3315   Thu Jul 29 10:39:43 2010 kiwamuUpdateSUSRe: installation of in-vac optics

I updated the last entry about the in-vac work (see here)

  3326   Thu Jul 29 22:08:32 2010 AlbertoUpdateSUSMore optics installed on the BS table

[Koji, Steve, Kiwamu, Alberto]

- This afternoon we installed a few new optics on the BS table: GR_PBS, GRY_SM2, GRY_SM1.

- We pulled up the cables so that we had more freedom to move one of the cable towers farther South.

- Then we re-leveled the table. PRM OSEMs were adjusted to be nominal insertions.

- Koji released the earthquake stops on BS but the readout of the OSEMs was apparently frozen on the MEDM screens.
Initially we thought it was a software problem. a nuclear reboot didn't solve it. We spent the following three hours investigating the cause.
Eventually it turned out that the earthquake stops on BS weren't actually fully released.

We opened the tank and accessed to BS. Releasing the earthquake stops in full solved the issue. The OSEMs readout went back to normal.

  3425   Mon Aug 16 19:12:18 2010 JenneUpdateSUSMore TT characterization

[Jenne, Yoichi]

We characterized Tip Tilts numbers 2 & 3 today.  Recall #4 is the one which Koji and I measured some time ago, and #s 1 & 5 have yet to be suspended (that's on the to-do list for tomorrow).

When we began looking at #3 (the one which had been in the BS chamber for a few days, but was removed for characterization) we found that the pitch pointing was way off.  The beam was way too low after reflection.  So we adjusted that (and got it right on the first try....a miracle!).  This does however make me pretty concerned about our in-chamber pointing.  Are we destroying our pointing during travel between the cleanroom and the chambers?  Is there anything we can do about it? Pointing doesn't seem to be lost when we move them around on the tables in the cleanroom, ie we can pick up a TT, move it, leave it for a while, move it back to the oplev, and the pointing still seems okay.  But the TT which was sent to the chambers came back with bad pointing. I'm sure this is related to the hysteresis we see in the pointing if we poke the top of the mirror holder versus the bottom when exciting pitch motion.

For both #2 and #3, we measured the frequency and Q of Pitch, Yaw, Pos, Side, Vert motion.  For the Vert motion, we measured both without and with EQ stops as dampers.  For the other modes, all were measured with the ECD backplane in place.  Pitch and Yaw were measured with reflection off of the mirror surface onto the PD, while Pos, Side and Vert were measured using the wire clamp on the mirror holder to obscure the beam as a shadow sensor.

TT #2

Pitch: Overdamped, no freq measured, Q < 1/2

Yaw: freq ~1.8Hz, Q between 2-7

Pos: freq ~1.75Hz, Q too low to measure, but above critically damped

Side: freq ~ 1.8Hz, Q~5

Vert no dampers: freq ~20Hz, Q~36

Vert with dampers on outer screws: freq~24Hz, Q~8,

TT #3

Pitch: no freq measured.  Q~1/2?  Upon being excited in Pitch, the beam started down way below the photodiode, came up a little past its DC place, and went back down a tiny bit.  So not quite overdamped.

Yaw: freq ~1.96Hz, Q very low

Pos: freq ~1.72Hz, Q~3

Side: freq ~1.85Hz, Q~6

Vert no dampers: freq ~20Hz, Q~75

Vert with dampers on outer screws: freq ~20Hz, Q~34  (Frequency stayed constant....we did several measurements both with and without the dampers...but the half life time changed significantly)

 

Things we noticed:  Koji and I had been concerned the last time we were looking at TT#2 because the frequency got lower and the Q seemed to get higher when we added the damping to the vertical blades.  Yoichi and I did not find that to be true today.  We did notice, however, that the EQ stop screws with the viton had been placed in the holes closer to the clamping point, whereas with TT #4 the screws had been placed in the holes farther from the clamping point.  We moved the screws on TT #2 to the outer holes, and noticed that the frequency increased slightly, and the Q significantly decreased.  We then followed this outer-hole philosophy when installing screws in TT #3.

To Do List: We need to suspend the ECDs and the Optics for the remaining two Tip Tilts, and to characterize them.  We also (probably farther-future) need to take transfer functions using a shaker / shake table with our spare Tip Tilt.  After all the TTs are suspended and have their modes measured, we will be ready for installation into the chamber during the next vent.

 

  3427   Mon Aug 16 23:39:29 2010 YoichiUpdateSUSMore TT characterization

Quote:

Things we noticed:  Koji and I had been concerned the last time we were looking at TT#2 because the frequency got lower and the Q seemed to get higher when we added the damping to the vertical blades.  Yoichi and I did not find that to be true today.  We did notice, however, that the EQ stop screws with the viton had been placed in the holes closer to the clamping point, whereas with TT #4 the screws had been placed in the holes farther from the clamping point.  We moved the screws on TT #2 to the outer holes, and noticed that the frequency increased slightly, and the Q significantly decreased.  We then followed this outer-hole philosophy when installing screws in TT #3.

The inner and outer screw holes of the EQ stop Jenne is talking about are shown in the photo below.

EQStopScrewHoles.jpg

  3437   Wed Aug 18 19:19:38 2010 JenneUpdateSUSFinal 2 TTs suspended!

[Jenne, Yoichi]

The final 2 Tip Tilts (#1 and #5) have been suspended.  We have designated #5 the spare.  It looks like there might be a teensy bit of dust on the AR surface of the optic in #5, right near the edge of the coating.  Not a critical issue if this one is the spare, although we should see if we can blow it off with the Nitrogen.  Both #1 and #5's optics were suspended using the thicker wire, 0.0036" diameter.  This leaves 4/5 TTs with this thick wire, and 1 of the 5 has the thin wire.

To do still: Balance both #1 and #5, and then measure the modes of each.  Then we'll be ready to install them into the chambers, and we'll reserve #5 for shake table TFs for some later date.

 

  3447   Fri Aug 20 15:22:09 2010 JenneUpdateSUSTTs done!!!

[Yoichi, Jenne]

Hooray!!! The Tip Tilts are completely done!  The only things remaining are (1) Install 4 TTs in chambers sometime in September and (2) do shake tests / take TFs of the spare.

Today we balanced and characterized #'s 1 and 5.  All 5 TTs are waiting happily on the flow bench in the cleanroom for installation.

  3455   Mon Aug 23 08:28:27 2010 steveUpdateSUSETMY sus damping restored
  3456   Mon Aug 23 15:24:24 2010 kiwamuConfigurationSUSwatchdogs off

For the new CDS test, I turned off the watchdogs for PRM, SRM, BS, ITMs and MCs.

I will restore these watchdogs after several hours from now.

 

  3457   Mon Aug 23 18:18:22 2010 kiwamuConfigurationSUSRe:watchdogs off

Now watchdogs are back.

The suspensions are well damped.

  3478   Fri Aug 27 13:41:02 2010 kiwamuUpdateSUSfix watchdogs

 [Joe, Kiwamu]

We found that the vertex watchdogs were not correctly running.

After I powercycled c1susaux, the problem was fixed successfully.

 

The symptom: the watchdogs didn't disable the coil signal even when PD_VAR signals went larger than the threshold values PD_MAX_VAR.

Also we replaced the label by the correct name "C1SUSAUX" on a tag which was tied to the front end machine mounted on the new 1X5 rack.

  3581   Fri Sep 17 03:06:06 2010 KojiUpdateSUSSOS sent for baking

Two SOS suspensions for the ETMs were disassembled and packed for cleaning and baking by Bob.

These suspensions have been stored on the X end flow bench long years, and looked quite old.

They have some differences to the modern SOSs.

- The top suspension block is made of aluminum and had dog clamps to fix the wires.
- The side bars are not symmetric: the side OSEM can only be fixed at the right bar (left side in the picture).
- EQ stops were made of Viton.
- One of the tower bases seems to have finger prints (of Mike Zucker?).

I found that the OSEM plates had no play. We know that the arrangement of the OSEMs gets quite difficult
in this situation. Therefore the holes of the screws were drilled with the larger drill.

We decided to replace all of the screws to the new ones as all of the screws are Ag plated and got corroded
by silver sulfide (Ag2S). I checked our stock in the clean room. We have enough screws.

Important note: Use stainless screws in aluminum / Silver-plated screws in stainless
There exists some study about galling: LIGO-G020394-00-D

Attachment 1: IMG_3596.jpg
IMG_3596.jpg
Attachment 2: IMG_3597.jpg
IMG_3597.jpg
  3582   Fri Sep 17 03:32:11 2010 KojiUpdateSUSArrangement of the SUS towers

The day before yesterday, I was cleaning a flow bench in the clean room.

I found that one SOS was standing there. It is the SRM suspension.

I thought of the nice idea:

- The installed PRM is actually the SRM (SRMU04). It is 2nd best SRM but not so diiferent form the best one.
==> Use this as the final SRM

- The SRM tower at the clean room
==> Use this as the final PRM tower.
==> The mirror (SRMU03) will be stored in a cabinet.

- The two SOS towers will be baked soon
==> Use them for the ETMs

This reduces the unnecessary maneuver of the suspension towers.

  3686   Sun Oct 10 18:28:25 2010 kiwamuSummarySUSITMX OSEM offsets

Because of the in-vac work on Oct. 4th (see this entry) , ITMX's OSEM offsets were changed.

The two upper OSEMs are still fine, but LL and LR seem to be out of the OSEM's range. 

The plot below shows the trends of LL's and LR's readouts for about two weeks. (The channel name are in the old convention, i.e. ITMY)

OSEM.png

 Some data were missing due to the upgrade of the frame builder.

 It is apparent that the offsets are changed after the in-vac work on Oct. 4th, and now they just show almost zero numbers.

 

The damping of ITMX can still work, if LL and LR are disabled.

At some point before pumping down, we have to check the leveling of the ITMX table again.

  3688   Mon Oct 11 10:51:36 2010 steveUpdateSUSOSEMs, OSEMs, OSEMs...those lovely little OSEMs
Attachment 1: 40dll.jpg
40dll.jpg
  3689   Mon Oct 11 16:09:10 2010 yutaSummarySUScurrent OSEM outputs

Background:
 The output range of the OSEM is 0-2V.
 So, the OSEM output should fluctuate around 1V.
 If not, we have to modify the position of it.

What I did:
 Measured current outputs of the 5 OSEMs for each 8 suspensions by reading sensor outputs(C1:SUS-XXX_YYPDMON) on medm screens.

Result:

  BS ITMX ITMY PRM SRM MC1 MC2 MC3
UL 1.20 0.62 1.69 1.18 1.74 1.25 0.88 1.07
UR 1.21 0.54 1.50 0.99 1.77 1.64 1.46 0.31
LR 1.39 0.62 0.05 0.64 2.06 1.40 0.31 0.19
LL 1.19 0.88 0.01 0.64 1.64 1.00 0.05 1.03
SD 1.19 0.99 0.97 0.79 1.75 0.71 0.77 0.93

 White: OK (0.8~1.2)
 Yellow: needs to be fixed
 Red: BAD. definitely need fix

  3699   Tue Oct 12 17:42:57 2010 yutaUpdateSUSvery first measurement of Q-values for MC1

Background:
 Data aquisition system is fixed, and now we can use the Dataviewer to measure Q-values of the ringdowns for each DOF, each optics.
 First of all, I measured MC1 suspention damping servo for a test.

What I did:
1. Used DAQ channels activated in this entry(#3690) to see and compare the ringdowns when the damping servo is on and off with the Dataviewer.

2. Plotted the data and fitted the ringdown using this formula;
  p[0]*exp(-p[1]*t)*sin(p[2]*t+p[3])+p[4]
 I used python's scipy.optimize.leastsq for the fitting.

3. Calculated the resonant frequency f0 and Q-value using following formulas;
  f0=2*pi*sqrt(p[1]**2+p[2]**2)
  Q=f0/(2*pi)/(2*p[1])

4. For plotting, I subtracted the offset(=p[4]).

All parameters I used for this measurement are automatically saved here;
  /cvs/cds/caltech/burt/autoburt/snapshots/2010/Oct/12/13:07/c1mcs.epics
(-1,0,1 for all matrix elements, GAIN=3,3,3,150 for POS,PIT,YAW,SIDE)

Result:
 Attached is the plot of each 4 DOF ringdown when servo is off and on.
 "servo off" means off for that DOF. Servo for the other 3 DOFs are on.

 As you can see clearly, the damping servo is working.

 The resonant frequencies and Q-values calculated from the fitting are as follows;

  servo off servo on
f0 (Hz) Q f0 (Hz) Q
POS 0.97 large 0.97 16
PIT 0.71 96 0.73 6.9
YAW 0.80 100 0.82 8.9
SIDE 0.99 large 0.99 27


 Resonant frequencies and Q-values have about 1% and 10% error respectively.
 I estimated it from my 2-time measurement of the POS ringdown.

Next work:
 - Find and modify some scripts to optimize the matrix elements
 - Calibrate the displacement
 - Do the same thing for other optics

Attachment 1: MC1ringdown.png
MC1ringdown.png
  3710   Thu Oct 14 00:04:46 2010 yutaUpdateSUSQ-value adjustment for MC dampings

Background:
 We need MC to be locked soon, so MC suspensions should be damped well(Q~5).

What I did:
1. Set the correct filters and turn all the damping servo on.

2. Kick the optics by adding some offset into the control loop.

3. Measure the Q-value of the ringdown with my eye.

4. If Q-value seems to be around 5, go to step #5. If not, change the filter gain and go to step #2.

5. Done! Do step #1-4 for all MCs.

All parameters I used for the servo are automatically saved here;
  /cvs/cds/caltech/burt/autoburt/snapshots/2010/Oct/13/20:07/c1mcs.epics

Result:
 Q-values of the damping servo for all MCs are set to around 5.
 Attached is the ringdown of MC2 for example.
 As you can see, my eye was very rough......

Next work:
 - Make a script that does steps #2-5 automatically.
    I need pyNDS module installed to get data using Python.
    I already wrote the rest of the script.
    We'll have Leo help us install pyNDS tomorrow.

Attachment 1: MC2ringdown.png
MC2ringdown.png
  3711   Thu Oct 14 00:53:44 2010 kiwamuUpdateSUSwhat's wrong with MC2

It turned out that the DC alignment of MC2 from epics doesn't helathily work.

For example, the pitch slider does drive the yaw alignment as well.

 

Is this somehow related to the unknown MC2 jump happened around September 10th ?? (see the trend below)

OSMEs.png

  3731   Fri Oct 15 22:16:22 2010 kiwamuUpdateSUSwhat's wrong with MC2

[Yuta, Suresh, Rana and Kiwamu]

 The DC alignment problem of MC2 was fixed.

There were some loosely connected cables on the backside of a VME rack which contains the MC2 SOS driver.

We pushed those connectors to make them tightly connected.  And then the problem disappeared.

 


(voltage unbalance on coils)

 Before fixing it Yuta opened the satellite box and measured the voltage across the coils using a voltmeter.

At that time UL and LR showed 20 times smaller voltages than that of the other two when we moved the DC alignment slider from min. to max. on the medm screen.

This behavior is exactly consistent with the wired motion of a beam spot which we saw when we were aligning MC2. 

 

(diagnostic using optical lever)

 After pushing the connectors, we made an optical lever using a red laser pointer in order to check the actual motion of MC2.

We confirmed that MC2 respond correctly to the alignment slider.

Quote:

 2010:Oct.14th:

It turned out that the DC alignment of MC2 from epics doesn't helathily work.

For example, the pitch slider does drive the yaw alignment as well.

 

  3736   Mon Oct 18 17:16:30 2010 JenneUpdateSUSOld PRM, SRM stored, new PRM drag wiped

[Jenne, Suresh]

We've put the old PRM and SRM (which were living in a foil house on the cleanroom optical table) into Steve's nifty storage containers.  Also, we removed the SRM which was suspended, and stored it in a nifty container.  All 3 of these optics are currently sitting on one of the cleanroom optical tables.  This is fine for temporary storage, but we will need to find another place for them to live permanently.  The etched names of the 3 optics are facing out, so that you can read them without picking them up.  I forgot to note the serial numbers of the optics we've got stored, but the old optics are labeled XRM ###, whereas the new optics are labeled XRMU ###. 

Koji chose for us PRMU 002, out of the set which we recently received from ATF, to be the new PRM.  Suresh and I drag wiped both sides with Acetone and Iso, and it is currently sitting on one of the rings, in the foil house on the cleanroom optical table.

We are now ready to begin the guiderod gluing process (later tonight or tomorrow).

  3737   Mon Oct 18 18:00:36 2010 KojiUpdateSUSOld PRM, SRM stored, new PRM drag wiped

- Steve is working on the storage shelf for those optics.

- PRMU002 was chosen as it has the best RoC among the three.

Quote:

[Jenne, Suresh]

We've put the old PRM and SRM (which were living in a foil house on the cleanroom optical table) into Steve's nifty storage containers.  Also, we removed the SRM which was suspended, and stored it in a nifty container.  All 3 of these optics are currently sitting on one of the cleanroom optical tables.  This is fine for temporary storage, but we will need to find another place for them to live permanently.  The etched names of the 3 optics are facing out, so that you can read them without picking them up.  I forgot to note the serial numbers of the optics we've got stored, but the old optics are labeled XRM ###, whereas the new optics are labeled XRMU ###. 

Koji chose for us PRMU 002, out of the set which we recently received from ATF, to be the new PRM.  Suresh and I drag wiped both sides with Acetone and Iso, and it is currently sitting on one of the rings, in the foil house on the cleanroom optical table.

We are now ready to begin the guiderod gluing process (later tonight or tomorrow).

 

  3741   Tue Oct 19 15:14:51 2010 JenneUpdateSUSPRM (little) update

[Jenne, Suresh]

We've aligned the guiderod and wire standoff to the PRM, each partly.  They have both been aligned to the correct distance above the scribe lines, but they have not yet been centered forward/backward along the thickness of the optic.  So, we're working on it...

  3746   Wed Oct 20 18:17:35 2010 Suresh, JenneUpdateSUSPRM assembly

We have positioned the guide rod and the wire-stand-off on the optic in the axial direction. 

We have selected six magnets whose magnetic strength is +/-5% of their mean strength (180 Gauss).  The measurement was made as follows:

1) each magnet was placed on its  end, on the top of a beaker held upside down. 

2) The Hall probe was placed directly under the magnet touching the glass from the other side (the inside of the beaker). 

This ensures that the relative position of the magnet and the probe remains fixed during a measurement.  And ensures that their separation is the same for each of the magnets tested. 

With this procedure the variation in the measured B field is less than +/- 10% in the sample of magnets tested.

  3761   Fri Oct 22 15:06:43 2010 JenneUpdateSUSArts and Crafts!

This afternoon I epoxied the guiderod and wire standoff to the new PRM.  I also epoxied the magnets that Suresh picked out to the dumbbell standoffs.  We'll let them all cure over the weekend, and then I'll glue the magnets to the optic on ~Monday.

Notes about the epoxy: 

Previously, we had been using the "AN-1" epoxy, which is gray, with a clear hardener.  Bob recommended we switch to "30-2", which is clear with clear, and has been chosen for use in aLIGO.  Both were vacuum approved, but the 30-2 has gone through ~2 months of testing at the OTF (Optics Test Facility?) over in Downs under vacuum, to check the level of outgassing (or really, non-outgassing).

The 30-2 is less viscous than the AN-1, and it takes less glue to do the same job, so we should keep that in mind when applying the epoxy.  When I put the glue next to the guiderod and standoff, it got wicked along the length of each rod, which is good.  I can't reach the whole length of the rod with my glue applicator because the fixture holding them in place blocks access, so the wicking is pretty handy.

 

I've also added the updated version of my Status Table for the suspensions.

Attachment 1: StatusTable.png
StatusTable.png
  3777   Mon Oct 25 11:39:06 2010 JenneUpdateSUSMagnets glued to PRM
This morning I glued the magnets to the PRM. Now we wait, and tomorrow afternoon (at the earliest), Suresh and I can balance the PRM.
Attachment 1: StatusTable.png
StatusTable.png
  3786   Tue Oct 26 15:57:10 2010 JenneUpdateSUSOne magnet broken, reglued

[Jenne, Suresh, Thanh (Bram's Grad Student)]

When we removed the grippers from the magnets on the PRM, one of the face magnets broke off.  This time, the dumbbell remained glued to the optic, while the magnet came off.  (Usually the magnet and dumbbell will stay attached, and both come off together).  I had 3 spare magnet-dumbbells, but only one of them was the correct polarization.  The strength of the spare magnet was ~128 Gauss, while the other magnets glued to the PRM are all ~180 Gauss.  We considered this too large a discrepancy, and so elected to reuse the same magnet as before. 

We removed the dumbbell from the optic using acetone.  After the epoxy was gently removed, we drag wiped the AR face of the optic (Acetone followed by Iso, as usual), being careful to keep all the solvent away from all the other glue joints.  We cleaned off the magnet with acetone (it didn't really have any glue stuck on it...most of the glue was stuck on the dumbbell), and epoxied it to a new dumbbell. 

The PRM, as well as the magnet-dumbbell gluing fixture are in the little foil house, waiting for tomorrow's activities.  Tomorrow we will re-glue this magnet to the optic, and Thursday we will balance the optic.  

This still leaves us right on schedule for giving the PRM to Bob on Friday at lunchtime, so it can bake over the weekend.

  3798   Wed Oct 27 16:15:35 2010 SureshUpdateSUSRe-glued magnet to the PRM

Thanh and I re-glued the magnet to the PRM following the procedure outlined by Jenne

The PRM in the gluing fixture has been placed in the little foil house and left to cure for a day.

If all goes well the balancing the PRM will be done tomorrow.

 

 

  3816   Fri Oct 29 01:18:03 2010 KojiSummarySUSPRM standoff glued

[Suresh Koji]

The standoff glued. The incandescent lamp set for curing the epoxy.


Jenne and Suresh did the balancing job. The next job was to glue it.

They ran out of the clear epoxy, and tried to use the grey epoxy which we used on the other suspensions for the upgrade.
They found that the solution A with grey color one was dried out and grainy.

We made a test piece of the grey epoxy (mixed with the solution B) in order to see the glue is still usable or not.
After the PMA party, we found that the glue was not stiffening but brittle. We judged that the grey epoxy is no longer useful.

Steve found a pack of Vac Seal in the chemical fridge. We decided to use this one for the gluing of the standoff.

After the gluing, we set an incandescent lamp to make the glue warm. 

Finally, we wrapped the suspension tower with Al foils and turned the HEPA fans again.

Attachment 1: IMG_3674.jpg
IMG_3674.jpg
  3824   Fri Oct 29 14:16:26 2010 JenneUpdateSUSPRM baking

[Suresh, Jenne]

We took a look-see at the PRM after the gluing from last night.  The balance is still okay.  The reflected beam is a teeny bit below the laser aperture (center of the beam maybe ~2mm below, so ~1mRad low).  This is within our okay range, since the DC offset that the OSEMs will give will be even more, and the coils can definitely handle this kind of offset.

We took the optic out of the tower, and gave it to Bob and Daphen to bake over the weekend.

  3840   Mon Nov 1 17:27:47 2010 JenneUpdateSUSPRM ready for installation into chamber

[Jenne, Suresh]

Over the weekend, Bob and Daphen gave the PRM a 48hr. vacuum bake.  This afternoon Suresh and I placed it back in the wire in the tower.  We used the microscope-on-translation-stage technique to make sure the scribe lines on each side of the optic are at the same height, and then secured the PRM using all of the EQ stops.  It is wrapped in foil, and ready for its journey into the IFO room.  When we next have the BS chamber open, we should put the PRM in, and move the current PRM to its final place on the ITMY table as the SRM.

  3867   Fri Nov 5 09:08:14 2010 steveUpdateSUSepoxy

Physical Electronics: Vac-Seal #288-6000 arriving Monday. Our last bag used last week had a p/n 1002003 with expiration date   .....2009 ? and it was stored in the

refrigerator all times. We are getting 68 small bags.

We should have precision gluing notes of epoxies/procedures used on our sus upgrade.

Attachment 1: 11081001.PDF
11081001.PDF
  3889   Thu Nov 11 01:34:27 2010 JenneUpdateSUSNew-Old ETM towers assembled

[Suresh, Jenne]

We have put together the new-old ETM towers.  These are the ones which were hanging out on the flow bench down the arm for years and years, and have recently been re-baked.  Interestingly, these are predominantly steel, whereas the newer ones are mostly aluminum.  This caused momentary drama while we scrounged for the correct screws (we needed more silver-plated screws than anticipated, since we were screwing into steel and not aluminum), however the miscellaneous clean hardware collection came to the rescue.  We did however use up all of the 1/4-20 3/4" silver plated screws, so hopefully no one else needs more later...

We only found 5 (enough for one of the two towers) spring plungers which are used to hold the OSEMs in place.  Suresh is sending an email to Steve to ask him to buy some more, so we can get them cleaned in time for use.  This is important, but not super urgent, since we have ~ 2 weeks before the ETMs will be ready for installation. 

Koji has not yet had a chance to inspect the ETM data sheets and choose for us which pair of ETMs to use (ATF sent the 4 ETMs in matched pairs).  So we will not begin the "arts and crafts" until tomorrow-ish.

  3902   Fri Nov 12 00:13:34 2010 SureshUpdateSUSETM assembly started

[Jenne, Suresh]

Selection of ETMs

Of the four ETMs (5,6,7 and 8) that are with us Koji gave us two (nos. 5 and 7) for use in the current assembly.  This decision is based on the Radius of Curvature (RoC) measurements from the manufacturer (Advanced Thin Films).   As per their measurements the four ETMs are divided into two pairs such that each pair has nearly equal RoC. In the current case, RoCs are listed below:

   

Radii of Curvature of ETMs
ETM # RoC from Coastline Optics (m) RoC from Advanced Thin Films (m)
5 57.6 60.26
6 57.4 54.58
7 57.1 59.48
8 57.9 54.8

 

The discrepancy between the measurements from these two companies leaves us in some doubt as to the actual radius of curvature.  However we based our current decision on the measurement of Advanced Thin Films. 

 

Assembly of ETMs

We drag wiped both the ETMs (5 and 7) and placed them in the Small Optic Gluing Fixture.  The optics are positioned with the High Reflectace side facing downwards and with the arrow-mark on the Wire Standoff side (big clamp).  We then used the microscope to position the Guide Rod and the Wire Standoff in the tangential direction on the ETMs (step 4 of the procedure specified in E010171-00-D)

We will continue with the rest of the assembly tomorrow.

 

  3928   Mon Nov 15 22:24:28 2010 SureshUpdateSUSSelection of Magnets

I have selected a set of 16 magnets which have a B field between 900 to 950 Gauss (5% variation) when measured in the following fashion.

I took a Petri-dish, of the type which we usually use for mixing the glue, and I placed a magnet on its end.  I then brought the tip of the Hall-probe into contact with the Petri-dish from the opposite side and adjusted the location (and orientation) of the probe to maximise the reading on the Gauss meter.

The distribution of magnets observed is listed below

 

Range of B Field (Gauss) # of Magnets
800-849 2
850-899 6
900-950
16

 

 

 

 

 

The set of sixteen has been have been placed inside two test tubes and left on the optical bench (right-side)  in the clean room.

 

 

  3936   Tue Nov 16 23:36:29 2010 Suresh, JenneUpdateSUSAssembly of ETMs

[Jenne, Suresh]

 

The ETM assembly has moved forward a couple of steps.  We have completed the following:

1) Positioning the guide rod and wire stand-off on both the ETMs (5 and 7)

2) The magnets had to be cleaned with an acetone wash as they had touched the plastic Petri-dish (not cleaned for vacuum).

3) The magnets and the Al dumb-bells have been glued together and left to cure in the gluing fixture.

4) The guide-rod and wire stand-offs have also been glued to the optic and left to cure for 24 hrs.

 

 

JD:  As you can see in my nifty status table, we are nearing the end of the suspension story.  

StatusTable.png

We are going to try (but can't guarantee) to get ETMX to Bob for baking by Friday at lunchtime, that way we can re-suspend it on ~Monday, and place it in the chamber.  Then we could potentially begin Green arm locking next week.  Steve has (hopefully!!) ordered the spring plungers for ETMY.  The receiving and baking of the spring plungers is the only current delay that I can foresee, and that only is relevant for one of the optics. 

We (who is going to be in charge of this?) still need to move the SRM OSEMs & cables & connectors to the ITMY chamber from the BS chamber. 

 

 

  3942   Wed Nov 17 23:45:20 2010 JenneUpdateSUSA bad day for suspensions

[Jenne, Suresh]

Today has been a downright miserable day in the world of suspension work. Thumbs down to that: 

Yesterday, we had glued 2 full sets of magnets to dumbbells.  Today, half of those broke.  I think I put too thin of a layer of glue on the magnets when gluing them to the dumbbells.  All magnet/dumbbell assemblies should pass the test of being picked up by the dumbbell while the magnet is stuck to the optical table or a razor blade.  6 of the 12 magnets failed this test. Suresh soaked the dumbbells that had been used in acetone, and scrubbed them, so we can reuse them when we reglue things tomorrow.  By some miracle, we have exactly one full set intact (for each set of 6, we need 4 of one direction and 2 of the other).  This was frustrating, but not yet a deal-breaker.  That part comes next....

I got ETMU05 nicely aligned in the magnet gluing fixture, and then was on my last check of whether the side magnets would be glued in the correct place when I realized that the fixture is all wrong for the ETMs.  This final check was added to the procedure after the drama with the ITMs of having the side magnets glued incorrectly as a result of the fixture being specific to the wedge angle of the optic.  Kiwamu and I had set the fixture to be just right for the ~1deg wedge corner station optics, but the ETMs have a 2.35deg wedge (according to the Coastline spec sheet, which is consistent with our measurements when placing the guiderod and standoffs).  Suresh and I need to reset the height of the optic in the fixture using more teflon sheets, but we don't have a whole lot of options ready in the cleanroom.  We're going to cut some more pieces and ask Bob to clean them tomorrow.  Since the way the fixture holds the teflon is a little hoaky, Suresh suggested just resting the optic on teflon pads, rather than screwing the teflon to the fixture, and then putting the optic on the pads.  We'll try Suresh's method tomorrow, and hopefully it will be pretty easy. 

At least the guiderods and standoffs were successfully glued to the optics....

Here's the updated Status Table.  I don't think we're going to be able to have an ETM ready for the chambers early next week, but we should still be able to have both ready for the Monday after Thanksgiving.  The spring plungers arrived today, and were given immediately to Bob and Daphen for cleaning.

StatusTable.png

  3953   Fri Nov 19 04:23:12 2010 SureshUpdateSUSCleaned and stuck magnets to dumbbells

To clean the glue off the magnets and dumbbells I soaked them in Acetone for about an hour and then scrubbed the ends clean with a lint free tissue soaked in Acetone. 

I then examined the ends under a microscope and found that while the flat faces were clean some of the grooves were still filled with glue.

 

Top Bottom

dumbells_before_ultrasonic_bath_2.jpg

dumbells_before_Ultrasonic_wash_1.jpg
 magnets_after_scrub.jpg magnets_after_scrub.jpg


While examining the magnets I found some small magnetic fibers stuck to the magnets.  Rana had mentioned these before as potential trouble makers which could degrade the high frequency performance of the OSEMs.

 Magnetic_Hair.jpg

 

To try and get the glue out of the grooves I put the dumbells through an ultrasonic bath for ten mins.  Most of the glue has been removed from the grooves.  Pics below

 

dumbells_after_ultrasonic_wash_1.jpg

dumbells_after_ultrasonic_wash_2.jpg

 

I proceeded try and recover the lost time by sticking the magnets back to the dumbbells.  Increased the quantity of the glue to a slightly larger amount than usual.  It should definitely squish out a bit now.  We will know tomorrow when we open the gluing fixture.

 

 

 

  3956   Fri Nov 19 16:13:09 2010 JenneUpdateSUSETMU05: magnets glued to optic

[Jenne, Suresh]

Suresh and I glued the intact-from-the-first-round magnets to ETMU05.  I accidentally got too much glue on one of the dumbbells (the glue was connecting the dumbbell to the gripper - bad news if we let that dry), and while I was cleaning it, the magnet broke off.  So I used one of the ones that Suresh had re-glued last night, and he is putting that one back together after some cleaning. 

To set the fixture, Suresh had the great idea of using small pieces of foil underneath the teflon pads to set the height of the optic in the fixture.  The optic still rests on the teflon pads, but with the foil we have finer control over how the optic sits.  Neat.  Since both ETMs are the same, we shouldn't have to do any more adjustment for the other ETM.

The updated Status Table:

StatusTable.png

  3958   Fri Nov 19 18:20:59 2010 SureshUpdateSUSGlue dynamics!

I examined the magnet-dumbbell joints under the microscope to see whether the glue that I applied yesterday was sufficient or in excess.

I think the pictures below speak for themselves !  

 

Too_much_glue_1.jpg Too_much_glue_2.jpg Too_much_glue_3.jpg

 

During the gluing process the Al dumbbell stays below and the magnet with a drop of glue on the lower face is placed on it and held in the teflon fixture.  As seen in the pics the glue seems to have run up the surface of the magnet and has not collected in the narrow part of the dumbell.  So it has climbed up along the narrow gaps between the magnet and the teflon fixture by capillary action. The glue stops where the teflon fixture ends, a little before reaching the free end of the magnet, which further indicates the capillary action.

 

 

Attachment 2: Too_much_glue_2.jpg
Too_much_glue_2.jpg
  3966   Mon Nov 22 18:39:53 2010 JenneUpdateSUSETMU07: magnets glued to optic. ETMU05: magnets removed

[Suresh, Jenne]

A story about minor disasters, and crises averted:

Once upon a time, in a cleanroom not so far away..... there lived an optic.  To preserve anonymity, we shall call him "ETMU05".  This optic had a rough day.  When removing the grippers from the magnet-to-optic fixture, 4 out of 6 magnets broke off the dumbbells (the dumbbells were still securely glued to the optic...these had come out of the same batch that had problems last week, same problem).  The remaining 2, LL and LR, were sadly of the same polarity.  This is bad, because it means that the "humans" taking care of "ETMU05" didn't check the polarity of the face magnets properly, and ensure that they were laid out in an every-other pattern (LL and UR having the same polarity, and LR and UL having the opposite).  So, the humans removed all magnets and dumbbells from ETMU05.  All remaining glue was carefully scrubbed off the surfaces of ETMU05 using lens paper and acetone, and the magnets and dumbbells were sonicated in acetone, scrubbed with a lint-free wipe, sonicated again, and then scrubbed again to remove the glue.  ETMU05 had a nice cleansing, and was drag wiped on both the AR and HR surfaces with acetone and iso.  ETMU05 is now on vacation in a nice little foil hut.

His friend, (let's call him ETMU07) had a set of magnets (with polarities carefully confirmed) glued to him.  The cleaned magnets and dumbbells removed from ETMU05 were reglued to their dumbbells, and should be dry by tomorrow. 

.....And then they lived happily ever after.  The End.

 


The revised schedule / status table:

StatusTable.png

  3979   Tue Nov 23 18:08:28 2010 JenneUpdateSUSETMU07: Balanced, standoff glued. ETMU05: Magnets glued to optic

[Koji, Jenne]

ETMU07 had its wire winched to the correct height, was balanced, standoff glued.  Can be ready for going into the oven tomorrow, if an oven is available.  (One of Bob's ovens has a leak, so he's down an oven, which puts everything behind schedule.  We may not be able to get anything into the oven until Monday).

ETMU05 had magnets glued to the optic.  Hopefully tomorrow we will winch the wire and balance the optic, and glue the standoff, and be ready to go into the oven on Monday.

The spring plungers were sonicated, but have not yet been baked.  I told Daphen that we'd like the optics baked first, so that we can get ETMX in the chamber ASAP, and then the spring plungers as soon as possible so that we can install ETMY and put the OSEMs in.

The updated status table:

StatusTable.png

  3984   Wed Nov 24 17:57:24 2010 JenneUpdateSUSETMU07: Baking. ETMU05: Needs side magnets reglued

[Jenne, Koji]

We removed ETMU07 from the suspension tower, after confirming that the balance was still good.  Bob put it in the oven to bake over the weekend.  The spring plungers and our spare magnets are all in there as well. 

I tried to remove the grippers from ETMU05, and when I did, both side dumbbells came off of the optic.  Unfortunately, I was working on getting channels into the DAQ, so I did not clean and reglue ETMU05 today.  However Joe told me that we don't have any ETMY controls as yet, and we're not going to do Yarm locking (probably) in the next week or so, so this doesn't really set any schedules back. 

The cleaning of ETMU05 will be tricky.  Getting the residual glue off of the optic will be fine, but for the dumbbells, we'd like to clean the glue off of the end of the dumbbells using a lint free wipe soaked in acetone, but we don't want to get any acetone in the magnet-to-dumbbell joint, and we don't want to break the magnet-to-dumbbell joint.  So we'll have to be very careful when doing this cleaning. 

The Status Table:

StatusTable.png

  3991   Mon Nov 29 22:50:07 2010 SureshUpdateSUSETMU05 Side Magnets glued back

[Suresh, Jenne]

ETMU05 : Gluing Side magnets back on to the optic.

The following steps taken in this process:

1) The two magnet+dumbell units which had come loose from the optic needed to be cleaned.  A lint free wipe was placed on the table top and a few cc of acetone was poured on to it.  The free end of the dumbbell was then scrubbed on this wipe till the surface regained its shine.  The dumbell was held at its narrow part with a forceps to avoid any strain on the magnet-dumbbell joint.

2) The optic was then removed from its gluing fixture (by loosening only one of the three retaining screws) and placed in an Al ring. The glue left behind by the side magnets was scrubbed off with a optical tissue wetted with Acetone. 

3) The optic was returned to the gluing fixture.  The position of the optic was checked by inserting the brass portion of the gripper and making sure that the face magnets are centered in it [Jenne doubled checked to be sure we got everything right].

4) The side magnets were glued on and the optic in the fixture has been placed in the foil-house.

If all goes well we will be able to balance the ETMU05 and give it to Bob for baking.

 

ETMU07 : It is still in the oven and we need to ask Bob to take out. It will be available for installation in the 40m tomorrow.  

 

  3997   Tue Nov 30 12:45:36 2010 kiwamuUpdateSUSfound a loose connection : ITMX damping

 Last night I found that the response of ITMX against the angle offsets were strage.

Eventually I found a loose connection at the feedthrough connectors of ITMX chamber.

 

So I pushed the connector hard, and then ITMX successfully became normal.

It looked like someone had accidentally kicked the cable during some works.

This bad connection had made unacceptable offsets in the OSEM readout, but now they seem fine.

ELOG V3.1.3-