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ID Date Author Type Categoryup Subject
  7379   Thu Sep 13 17:19:45 2012 JenneUpdateSUSMirrors being installed on active TTs

I have given Den 4 G&H R>99.99% mirrors to be installed on the 4 active tip tilts.  He's in there working on things (incl. installing and balancing the pitch of the mirrors) right now.  He'll elog his work later.

  7384   Fri Sep 14 01:05:36 2012 DenUpdateSUSMirrors being installed on active TTs

Quote:

I have given Den 4 G&H R>99.99% mirrors to be installed on the 4 active tip tilts. 

 I've installed the mirrors on 4 tip-tilts. I was able to align 3 of them in pitch, the last one has a screw with damaged thread, I'll continue with it tomorrow.

Alignment accuracy in pitch is ~0.1 mrad. Mirrors oscillate a lot probably due to air flow coming from the side wall.

  7387   Fri Sep 14 12:51:43 2012 JenneUpdateSUSNeed risers for active TTs

I was helping Den get started in the cleanroom yesterday, and I noticed that the new active TTs, like the old passive ones, are set to be 4" from the table.  So, like the old ones, we need 1.5" risers to get the center of the mirror up to our in-vac 5.5" beam height.  I didn't see any risers in there when I was looking around. 

Steve says he still has the drawing that he gave to the shop for the old tip tilts, so he'll double check that the dimensions are the same, and then ask the shop to make 4 more.

  7408   Wed Sep 19 09:32:24 2012 SteveUpdateSUSalignment centering jig

SOS alignment tool with ID 9.5 and 6.3 mm

Attachment 1: IMG_1639.JPG
IMG_1639.JPG
Attachment 2: IMG_1651.JPG
IMG_1651.JPG
  7428   Fri Sep 21 22:43:51 2012 DenUpdateSUSTT alignment

I did TT alignment using red laser and QPD.

P9210079.JPG       P9210092.JPG

 I had a problem aligning TT with frame number SN-035 as some screws are damaged so all what I could move were 2 blades on the sides of the mirrors. But this was not enough to align pitch and yaw simultaneously.  It is possible to align pitch only, but then I got a huge yaw angle (~0.05-0.1 rad). The only option I had was to make a reasonable alignment in yaw and then suspend several washes on the screw on the bottom of the mirror to align pitch.

Attached are flag positions inside coils. 1 - SN034, 2 - SN012, 3 - SN006, 4 - SN035. For each TT there are 4 pictures with flag 1-4: UL, LL, UR, LR

Attachment 3: 1.pdf
1.pdf 1.pdf 1.pdf 1.pdf
Attachment 4: 2.pdf
2.pdf 2.pdf 2.pdf 2.pdf
Attachment 5: 3.pdf
3.pdf 3.pdf 3.pdf 3.pdf
Attachment 6: 4.pdf
4.pdf 4.pdf 4.pdf 4.pdf
  7443   Wed Sep 26 17:09:15 2012 DenUpdateSUSTT

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

  7446   Thu Sep 27 15:21:04 2012 SteveUpdateSUSTT height adaptor & PTICH damping

Quote:

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

Attachment 1: 09271201.PDF
09271201.PDF
Attachment 2: IMG_1656.JPG
IMG_1656.JPG
Attachment 3: IMG_1654.JPG
IMG_1654.JPG
  7453   Mon Oct 1 07:25:48 2012 SteveUpdateSUSMC2 & ETMX sus damping restored
  7458   Mon Oct 1 17:03:01 2012 steveUpdateSUSETMY oplev relayed

Quote:

Quote:

Quote:

 

 The typical sign of a dying gas laser is that it glows for a few minutes only. The power supplies are fine.

Two new  JDS - Uniphase 1103P lasers ( NT64-104 )  arriving on Monday, May 21

 Yesterday I swapped in new He/Ne laser with output power 3.5 mW  The return spot on qpd is large ~6mm in diameter and 20,500 counts

The spot size reduction require similar layout as ETMX oplev.

 The oplev path is relayed and the spot size on the qpd is reduced. I still have to clean up and replace "Miki Mouse" lens holder.

There was no IP-ANG coming out of the chamber at this time!

 I did relayed the oplev path with new  f 500 mm lens

Attachment 1: IMG_1673oplevETMY.jpg
IMG_1673oplevETMY.jpg
  7460   Tue Oct 2 07:45:49 2012 SteveUpdateSUS MC2 & PRM sus damping restored
  7466   Wed Oct 3 07:41:23 2012 SteveUpdateSUS MC2 sus damping restored

This is the third morning in a row that the MC2 was tripped.  Would you look at it Koji?

  7473   Wed Oct 3 23:24:05 2012 KojiUpdateSUS MC2 sus damping restored

Quote:

This is the third morning in a row that the MC2 was tripped.  Would you look at it Koji?

This may be cause by the impact of crazy WFS signal after the lock loss.
The auto locker is not fast enough to shut the WFS down before the mirrors are kicked.

Jenne and I discussed the issue and agreed that this can be solved by implementing
the same triggering algorithm as the LSC triggers.

Give us a bit more time to work on this.

  7478   Thu Oct 4 14:08:49 2012 jamieUpdateSUSsuspensions damped

All suspension damping has been restored.

  7484   Thu Oct 4 22:27:54 2012 KojiUpdateSUSHow about the slow machines?

One terrible concern of mine is that the slow machines were rebooted at the power interruption.
Based on the elog entries, I assume they have not been burtrestored...

If this is true, they may cause some weird behaviors of the PSL/IOO electronics.

 

  7485   Thu Oct 4 22:35:16 2012 DenUpdateSUSHow about the slow machines?

Quote:


Based on the elog entries, I assume they have not been burtrestored...

 Do you know how to burtrestore or restart slow machines?

Edit by Den: I did burtrestore of c1psl.snap from 2 days ago. Still slow machines behave not normal. For example, if I sweep C1:PSL-FSS_SLOWDC, SLOW monitor value does not change.

  7489   Fri Oct 5 04:34:31 2012 ranaUpdateSUSHow about the slow machines?

Quote:

Quote:


Based on the elog entries, I assume they have not been burtrestored...

 Do you know how to burtrestore or restart slow machines?

Edit by Den: I did burtrestore of c1psl.snap from 2 days ago. Still slow machines behave not normal. For example, if I sweep C1:PSL-FSS_SLOWDC, SLOW monitor value does not change.

 Problems with Slow Machines?

Read ELOG

  7496   Sun Oct 7 15:05:42 2012 DenUpdateSUS MC2 sus damping restored

Quote:

This is the third morning in a row that the MC2 was tripped.

 MC2 was tripped again. I think the answer is that watchdog's critical value was too small C1:SUS-MC2_PD_MAX_VAR = 10, so seismic could trip MC2. I've changed the value to 100.

mc2.png

  7500   Mon Oct 8 10:56:59 2012 JenneUpdateSUSETMX slow machine dead??

I think the ETMX slow machine might be dead.  All of the regular FE readbacks are fine, and the c1iscex FE computer looks fine, but the slow readbacks are all whited out. 

I turned off the damping loops for ETMX, since I don't have access to the watchdog disable/enable switch.  I guess checking this out will be task #1 for Monday morning.

  7502   Mon Oct 8 11:44:21 2012 JenneUpdateSUSETMX slow machine fine

Quote:

I think the ETMX slow machine might be dead.  All of the regular FE readbacks are fine, and the c1iscex FE computer looks fine, but the slow readbacks are all whited out. 

I turned off the damping loops for ETMX, since I don't have access to the watchdog disable/enable switch.  I guess checking this out will be task #1 for Monday morning.

 For lack of a better idea, I keyed the crate.  The computer came back up just fine, ETMX is happily damped again.

  7507   Mon Oct 8 22:07:46 2012 ranaUpdateSUSDoors on, ready to pump

Quote:

All oplevs need a little realignment, especially ETMY, which had it's lens removed (Rana has a Wall of Shame photo of this, which is why it was removed by him).  Steve will look into this tomorrow, after he starts pumping.

 The shame:

20120921_200637.jpg

There is no situation in which it is OK to install a mount like this. Steve had installed this flaky and shaky mount to optimize the beam size on the OL QPD.

Everyone in the lab should know better. Putting in something like this is just like sabotage - it creates extra noise in our interferometer in a sneaky way and just makes locking harder. All mounts for anything useful (including QPDs) must have highly rigid mounts. 

Use the example from the PSL relayout: use the 3/4" steel mounts and the wide aluminum bases from Newport. No more art projects using home made mounting crap, Steve.

  7511   Tue Oct 9 17:16:14 2012 DenUpdateSUSdiagonalization

I went inside to align the beam on WFS and noticed that oscillations in yaw are ~10 times stronger then in pitch. I've plot rms of pitch and yaw measured by LID sensors and saw that MC3 yaw rms motion is a few times larger then pitch.

Also MC1 input diag matrix does not diagonalize signals for pitch and yaw. In the spectrums of these signals all 4 resonance are equally seen during the free swinging. I think we should rediagonalize MC1.

Another thing is that if MC1 and MC3 are on the same stack,  pitch and yaw spectrums of these mirrors should be comparable. But MC1 signal is ~2-3 times larger then of MC3. I think we should correct calibration.

Attachment 1: mc123_rms.pdf
mc123_rms.pdf
Attachment 2: mc1_diag.pdf
mc1_diag.pdf
Attachment 3: mc123_rms.pdf
mc123_rms.pdf
  7512   Tue Oct 9 17:33:37 2012 jamieUpdateSUSdiagonalization

Quote:

I went inside to align the beam on WFS and noticed that oscillations in yaw are ~10 times stronger then in pitch. I've plot rms of pitch and yaw measured by LID sensors and saw that MC3 yaw rms motion is a few times larger then pitch.

What are "LID" sensors?  Do you mean the OSEM shadow sensors?  I'm pretty sure that's what you meant, but I'm curious what "LID" means.

 

  7516   Wed Oct 10 02:20:34 2012 ranaUpdateSUSOptical Lever QPD mods

 Since we upgraded the CDS system, I guess our ADC ranges have gone up but we never did anything to the OLs to match the ADC ranges. From Liz's daily summary page of the OL, I see this:

C1-CORE_OPTICS_SUM_DATA_ALL_TIME_0-1033801216-86400.png

So we need a factor of 5-10 increase in the electronics gain (why isn't the BS SUM on there?). This might be accomplished in the head, but for the ones with whitening boards, might be better to do there.

(** add to Jamie's list of long term tasks **)

  7523   Wed Oct 10 21:50:39 2012 SUS_DiagonalizerUpdateSUSOptics kicked
All suspended optics have been kicked at Wed Oct 10 21:50:39 PDT 2012. Watchdogs will be reengaged in 90 minutes.
  7524   Thu Oct 11 00:22:58 2012 SUS_DiagonalizerUpdateSUSOptics kicked

Quote:
All suspended optics have been kicked at Wed Oct 10 21:50:39 PDT 2012. Watchdogs will be reengaged in 90 minutes.


New SUS input matrix diagonalization complete.
  7525   Thu Oct 11 00:28:30 2012 DenUpdateSUSdiagonalization

I've written MC123 input matrixes to the front-end.

MC1 diagonalization is poor, better then before, but still pitch is seen in pos and yaw. Either smth is malfunctioning or flags touch sensors and do not move freely. On the plot mc1_new black lines - before, red - after rediagonalization.

Attachment 1: mc1_new.pdf
mc1_new.pdf
Attachment 2: mc123_new.pdf
mc123_new.pdf
  7526   Thu Oct 11 01:30:11 2012 DenUpdateSUSdiagonalization

Quote:

MC1 diagonalization is poor, better then before, but still pitch is seen in pos and yaw. Either smth is malfunctioning or flags touch sensors and do not move freely. On the plot mc1_new black lines - before, red - after rediagonalization.

 I've actuated on MC1 with UL, UR, LR, LL coils in turn and measured sensor readings. All coils separately work fine from the first look.

On the plot: black - free mirror, blue - UL coil actuation, green - UR, grey - LR, red - LL.

Attachment 1: mc1_coils.pdf
mc1_coils.pdf
  7528   Thu Oct 11 11:36:52 2012 SteveUpdateSUSTT pitch adjustment

Tip Tilt pitch adjustment on existing-in vacuum suspension. This can be added by a simple installation of a 1.25" long 2-56 threaded rod with nuts.

Attachment 1: IMG_1702.JPG
IMG_1702.JPG
  7532   Thu Oct 11 14:40:20 2012 DenUpdateSUSdiagonalization

Quote:

MC1 diagonalization is poor, better then before, but still pitch is seen in pos and yaw. Either smth is malfunctioning or flags touch sensors and do not move freely. On the plot mc1_new black lines - before, red - after rediagonalization.

 I've manually corrected MC1 input matrix by looking at UL, UR, LL, LR transfer functions between each other. This improved pos significantly and slightly yaw.

Attachment 1: mc1.pdf
mc1.pdf
  7535   Fri Oct 12 10:39:45 2012 SteveUpdateSUSTT PITCH damping

Quote:

Quote:

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

 We can only decide the need of pitch damping when the coils are activated.

Attachment 1: IMG_1709.JPG
IMG_1709.JPG
  7536   Fri Oct 12 14:01:33 2012 KojiUpdateSUSTT PITCH damping

Quote:

 We can only decide the need of pitch damping when the coils are activated.

Could you tell us why? Are you thinking about induced current damping?

  7538   Fri Oct 12 16:59:26 2012 steveUpdateSUSTT PITCH damping

Quote:

Quote:

 We can only decide the need of pitch damping when the coils are activated.

Could you tell us why? Are you thinking about induced current damping?

      I  was wrong The instability will be the same when the coils are actuated.

  7544   Mon Oct 15 08:08:33 2012 steveUpdateSUSPRM damping restored

Quote:

Quote:

Quote:

Quote:

Yuta claims he fixed the PRM oplev by centering it the other day, but no one has left it on and watched it for a long while, to make sure it's okay.  We watched it now for ~2 min, and it was good, but we're leaving the oplevs off anyway for the night.  Tomorrow we should restore PRM (it's currently restored), turn on the oplevs, and let it sit to make sure it doesn't go crazy.

 

 PRM oplev servo was turned on with PITgain 0.5  and YAWgain  -0.7

Note: gain settings were PIT  1.0  and  YAW --0.5   on Jun 1, 2012 that I measured Feb 23, 2012

 It is still oscillating. Gains turned down to zero.

 Earthquake test our suspensions            PRM damping restored.             Oplev servo gains turned to zero.

 The PRM damping restored. Oplev  PIT gain  0.15 and YAW  gain   -0.3 turned to zero.

  7548   Mon Oct 15 14:51:16 2012 JenneUpdateSUSSUS were kicked hard as a result

Quote:

Apparently all of the ION pump valves (VIPEE, VIPEV, VIPSV, VIPSE) opened, which vented the main volume up to 62 mTorr.  All of the annulus valves (VAVSE, VAVSV, VAVBS, VAVEV, VAVEE) also appeared to be open.  One of the roughing pumps was also turned on.  Other stuff we didn't notice?  Bad. 

 Several of the suspensions were kicked pretty hard (600+ mV on some sensors) as a result of this quick vent wind.  All of the suspensions are damped now, so it doesn't look like we suffered any damage to suspensions.

  7551   Mon Oct 15 22:16:09 2012 JenneUpdateSUSAll oplev gains turned to 0

Steve has promised to fix up all of the oplevs, but it hasn't happened yet, so I've turned all of the oplev gains to zero, so that when the optics are restored we don't have to quickly click them off.

Oplev values that were changed to zero:

PRM P=0.15, Y=-0.3

SRM P=-2.0, Y=2.0

BS P=0.2, Y=-0.2

ITMY P=2.1, Y=-2.0

ITMX P=1.0, Y=-0.5

ETMX P=-0.2, Y=-0.2

ETMY P=0.5, Y=0.6

Also, PRCL was changed in the LSC input matrix from REFL33I to AS55I, since there is no REFL beam out of the IFO :(

  7566   Wed Oct 17 08:30:49 2012 SteveUpdateSUS PTICH damping needed

Quote:

Quote:

  [Koji, Steve, Den]

TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.

We are moving towards electronics testing.

Atm1,  TT 1.5" high adaptor base will be back from the shop in 10 days.

Atm2,  There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap

Atm3,  Adjustable Al -disc that contains a small magnet is purely designed.

We have to come up with a solution to have damping in PITCH

 Pitch damping solution needed! It should be in the machine shop already.

  7568   Wed Oct 17 11:15:05 2012 DenUpdateSUS PITCH damping needed

Quote:

 

 Pitch damping solution needed! It should be in the machine shop already.

I think we can put ø2mm × 10mm long magnetic material inside 4 holes with actuation magnets. Then magnetic field on the other side of the mirror will be close to one produced by actuation magnet. Magnetic cylinder center of inertia will be in the vertical plane where mirror's center of inertia is. So this should not change alignment significantly. Eddy current dumping will be applied to the end of the magnetic cylinder opposite to the magnet using aluminium disks, we have them in the clean room.

pitch_damping.png

  7571   Thu Oct 18 02:42:38 2012 DenUpdateSUS PITCH damping needed

Quote:

 

I think we can put ø2mm × 10mm long magnetic material inside 4 holes with actuation magnets. Then magnetic field on the other side of the mirror will be close to one produced by actuation magnet. Magnetic cylinder center of inertia will be in the vertical plane where mirror's center of inertia is. So this should not change alignment significantly. Eddy current dumping will be applied to the end of the magnetic cylinder opposite to the magnet using aluminium disks, we have them in the clean room.

 I've tested this approach. As we do not have required cylinders with high magnetic permittivity, I replaced them with magnets simular to actuator magnets ø2mm × 3mm long. Using them and aluminium disks from other TT I've made a "pitch dumping" construction.

DSC_4759.JPG

Pitch Q reduced but not that much as I could expect. I did a ringdown test. 

Plots:

yaw ringdown using original construction     |  yaw ringdown with added pitch damping

------------------------------------------------------------------------------------------------------------------------

pitch ringdown using original construction   |  pitch ringdown with added pitch damping

    yaw_nodamp_20.JPG   yaw_damped_13.JPG

pitch_nodamp_30.JPG     pitch_damped_10.JPG

 

 From this data I've estimated Q factor for yaw (135 vs 88) and pitch (192 vs 77) (original vs added pitch damping). Thess results diverges with the ones obtained by designes. They measured Q~40-50 for original construction. Pitch and yaw have 2 close resonances so this time domain method can not be very precise. I've measured the same with SR785.

yaw.pngpitch.png

In these comparison plots excitation was not the same as coils are not plugged in yet, but resonance Q factors can be compared.

 

  7583   Fri Oct 19 18:30:07 2012 DenUpdateSUS PITCH damping needed

CQuote:

 

 From this data I've estimated Q factor for yaw (135 vs 88) and pitch (192 vs 77) (original vs added pitch damping).

 I've made a more precise measurement of pitch damping using spectrum analyzer.

damp.png   pitch.png

Measurements confirm that damping using small actuation magnets reduces pitch Q by a factor of 4 and is not enough.

  7585   Sat Oct 20 01:23:56 2012 DenUpdateSUS PITCH damping needed

Quote:

Measurements confirm that damping using small actuation magnets reduces pitch Q by a factor of 4 and is not enough.

 I've tested the idea to use coils as eddy current dampers. I terminated them with a wire and measured Q factor during the ringdown test. Sadly, I did not see any significant damping and Q was ~150. We need stronger magnets if we want eddy current dumping down to Q~1.

P1010059.jpg      P1010060.jpg    P1010058.jpg

  7586   Sat Oct 20 20:37:55 2012 DenUpdateSUS PITCH damping needed

Quote:

 

 We need stronger magnets if we want eddy current dumping down to Q~1.

 I've inserted 10mm * 10mm magnets to the 4 corner holes on the front side of the mirror frame according to actuation magnets polarity. I realigned TT and measured Q factor for pitch and yaw, it was 5-10.

DSC_4778.JPG     pitch.JPG   yaw.JPG

 

I was able to do it for 1 TT only, because others have smaller (~0.1 mm) hole diameter and magnets can't go inside. I tried to warm holes up to 850 F but still was not able to insert a magnet.

DSC_4776.JPG

  7588   Mon Oct 22 11:26:12 2012 ranaUpdateSUS PITCH damping needed

 

Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.

  7593   Tue Oct 23 01:46:53 2012 DenUpdateSUS PITCH damping needed

Quote:

 

Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.

 I've made SolidWorks models of damping bracket and eddy current disk. They will me manufactured and used instead of old ones. New bracket will be mounted in exactly the same place where the old one was. Drawings might not be complete but all dimensions are in the models so we can fix drawing tomorrow before going to machine shop.

I think we can use ring magnets for passive damping. Then we won't have the vent problem. I've found some at K&J Magnetics, we can get them any time. Magnets are Ni-Cu-Ni (fine for vacuum?) Diameter is 3/8'' with advertised tolerence 0.004'', so they should fit the holes.

Attachment 1: Mirror_Holder_ECD_NEW_DRAWING.PDF
Mirror_Holder_ECD_NEW_DRAWING.PDF
Attachment 2: TT_DAMPING_DRAWING.PDF
TT_DAMPING_DRAWING.PDF
  7595   Tue Oct 23 09:37:33 2012 SteveUpdateSUS passive TT adjustment correction

Quote:

Tip Tilt pitch adjustment on existing-in vacuum suspension. This can be added by a simple installation of a 1.25" long 2-56 threaded rod with nuts.

 We should check that  their sus wire diameter are 0.0017"  All 2-56 hardware are in and  Bob is cleaning them.

Attachment 1: IMG_1745.JPG
IMG_1745.JPG
  7598   Tue Oct 23 17:12:30 2012 DenUpdateSUS PITCH damping needed

 Koji and Steve pointed out that previous design  of a damping bracket was a bit complicated to manufacture. So I made it simpler and also added a tap hole for original yaw damping. We'll give drawing to Mike in the machine shop tomorrow morning.

I've purchased K&J magnets for eddy current damping, they should be here in 2 days. 

Attachment 1: simple_drawing.PDF
simple_drawing.PDF
  7602   Tue Oct 23 18:18:29 2012 JenneUpdateSUS PITCH damping needed

Quote:

Quote:

 

Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.

 I've made SolidWorks models of damping bracket and eddy current disk. They will me manufactured and used instead of old ones. New bracket will be mounted in exactly the same place where the old one was. Drawings might not be complete but all dimensions are in the models so we can fix drawing tomorrow before going to machine shop.

I think we can use ring magnets for passive damping. Then we won't have the vent problem. I've found some at K&J Magnetics, we can get them any time. Magnets are Ni-Cu-Ni (fine for vacuum?) Diameter is 3/8'' with advertised tolerence 0.004'', so they should fit the holes.

 Den mentioned that the disks will have threaded holes, and that he has made a note to that effect on the paper copy of the drawing that he will bring to Mike at the shop.  Also, all threaded holes in the new plate are marked on the paper copy.

  7604   Wed Oct 24 01:02:10 2012 KojiUpdateSUS PITCH damping needed

Wow... This is even more complicated than the original "Y" design...

  7619   Thu Oct 25 08:04:45 2012 SteveUpdateSUSmy assesment of the folding mirror (passive tip-tilt) situation

Quote:

The thinner wire has a history that it did not improve the hysteresis (ask Jenne). Nevertheless, it's worth to try.

If you flip the clamp upside-down, you can lift the clamping point up. This will make the gravity restoring torque stronger.
(i.e. Equivalent effect to increasing the mass)

Luckily (or unluckily) the clamp has no defined location for the wire as we have no wire fixture.
Therefore the clamp will grab the wire firmly even without milling.

 The wire clamps should be taken off at the top and at the mirror holder. They need a mill touch up. It would be nice to have the centering jig from LLO for the 0.0017"

The clamps in this condition are really bad. It can sleep, it is not adjustable.

 

Attachment 1: IMG_1748.JPG
IMG_1748.JPG
  7625   Thu Oct 25 20:44:11 2012 JenneUpdateSUSTip tilts in progress

Jamie and I spent some time with tip tilt SN001 this afternoon.  This was installed as SR3, so I was going to put a new LaserOptik mirror in there.  I accidentally snapped one of the wires (I forgot how strong the magnets are - one zipped from the mirror holder and captured the wire).  Jamie and I put the new LaserOptik mirror in, with the wedge correct, but we need to re-resuspend it with the 0.0036" wire tomorrow.  We'll also keep working on re-pitch aligning the other optics.

PR2 needs to be put back as a G&H, and we need to put a LaserOptik mirror into PR3.

  7630   Fri Oct 26 10:44:25 2012 JenneUpdateSUSTip tilts in progress

Quote:

Jamie and I spent some time with tip tilt SN001 this afternoon.  This was installed as SR3, so I was going to put a new LaserOptik mirror in there.  I accidentally snapped one of the wires (I forgot how strong the magnets are - one zipped from the mirror holder and captured the wire).  Jamie and I put the new LaserOptik mirror in, with the wedge correct, but we need to re-resuspend it with the 0.0036" wire tomorrow.  We'll also keep working on re-pitch aligning the other optics.

PR2 needs to be put back as a G&H, and we need to put a LaserOptik mirror into PR3.

 We resuspended SN001 this morning with 0.0036" wire.  We did as Koji suggested, and flipped the wire clamp so the suspension point is a little higher, so we'll see if that helps.  We put LaserOptik mirror SN1 into this TT001.

We put the G&H mirror back into TT004, which is PR2.  We also put a LaserOptik mirror (SN5) into TT005, which is SR3.

Jamie is working on re-pitch aligning TT004 and TT005 (we already did 001), then we can re-install them in the vacuum system later this afternoon.

ELOG V3.1.3-