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ID Date Author Type Categoryup Subject
  7156   Mon Aug 13 00:33:06 2012 MashaUpdateGeneralMysterious banging on emergency door

[Masha, Sasha]

Sorry to spam the e-log, but did someone come knock loudly on the emergency exit door a few moments ago? It gave Sasha and I quite a fright, and we are rather worried.

  7157   Mon Aug 13 01:33:55 2012 DenUpdateGeneralMysterious banging on emergency door

Quote:

[Masha, Sasha]

Sorry to spam the e-log, but did someone come knock loudly on the emergency exit door a few moments ago? It gave Sasha and I quite a fright, and we are rather worried.

 Probably, security. You can call 5555 and ask them. Otherwise you can ask them to come and check everything.

  7158   Mon Aug 13 09:59:05 2012 KojiUpdateGeneralMysterious banging on emergency door

You mean 5000?

Quote:

Probably, security. You can call 5555 and ask them. Otherwise you can ask them to come and check everything.

 

  7160   Mon Aug 13 15:31:09 2012 steveUpdateGenerallarger optical tables at the ends

I'm proposing larger optical tables at the ends to avoid the existing overcrowding. This would allow the initial pointing and optical level beams to set up correctly.

The existing table is 4 x 2 would be replaced by 4' x 3'   We would lose only ~3" space  toward exist door.

I'm working on the new ACRYLIC TABLE COVER for each end that will cost around $4k ea.  The new cover should fit the larger table.

Let me know what you think.

Attachment 1: ETMYtable.jpg
ETMYtable.jpg
Attachment 2: ETMY4X3.jpg
ETMY4X3.jpg
  7163   Mon Aug 13 18:00:30 2012 jamieUpdateGenerallarger optical tables at the ends

Quote:

I'm proposing larger optical tables at the ends to avoid the existing overcrowding. This would allow the initial pointing and optical level beams to set up correctly.

The existing table is 4 x 2 would be replaced by 4' x 3'   We would lose only ~3" space  toward exist door.

I'm working on the new ACRYLIC TABLE COVER for each end that will cost around $4k ea.  The new cover should fit the larger table.

Let me know what you think.

I'm not sure I see the motivation.  The tables are a little tight, but not that much.  If the issue is the incidence angle of the IP and OPLEV beams, then can't we solve that just by moving the table closer to the viewport?

The overcrowding alone doesn't seem bad enough to justify replacing the tables.

  7179   Tue Aug 14 15:58:44 2012 JenneUpdateGeneralTranslation to English: larger optical tables at the ends

Quote:

Quote:

I'm proposing larger optical tables at the ends to avoid the existing overcrowding. This would allow the initial pointing and optical level beams to set up correctly.

The existing table is 4 x 2 would be replaced by 4' x 3'   We would lose only ~3" space  toward exist door.

I'm working on the new ACRYLIC TABLE COVER for each end that will cost around $4k ea.  The new cover should fit the larger table.

Let me know what you think.

I'm not sure I see the motivation.  The tables are a little tight, but not that much.  If the issue is the incidence angle of the IP and OPLEV beams, then can't we solve that just by moving the table closer to the viewport?

The overcrowding alone doesn't seem bad enough to justify replacing the tables.

Steve pointed out to me (this is not in his original elog, although you can see it in the photo if you look closely), that we can't really move the table legs any closer to the chamber.  We have maybe 3" of clearance between the table leg and the blue support tube that supports the bottom of the stack.  Therefore, we can't just

So Steve's proposal is to leave the legs exactly where they are, and just put a larger table on those legs.  This leaves 9" unsupported on the chamber side, and 3" unsupported on the far side.  The tables are 4" thick. 

Steve also mentions that we will lose 1.5" on all 4 sides of the table, with the new acrylic boxes, so we'll be down to 1'9" unless we get the larger table, in which case we'd have 2'9", and 3'9" on the long direction.

I would like to see a sketch of the end tables, so we can see if 1'9" x 3'9" is enough.  Manasa is working on a new end table layout in parallel to the ringdown stuff.  If we're actually concerned about the input angle of the oplevs, then to fix that we need to either get the bigger table and hang it off the edge of the legs, or perhaps as Dmass suggested, get a "doggy cone collar", and give ourselves a larger opening angle of access to the viewport, from the current table location.

 

  7194   Wed Aug 15 16:01:47 2012 steveUpdateGenerallarger optical tables at the ends ?

The drawing of the 4' x 2'  table cover can be seen at entry  #6190 The new proposed wall #7106  The yellow acrylic would be ~ 0.25" thick and it will be the inside. It is not shown on the drawing.

Question remaining: should get a larger table 4' x 3' as outlined by red lines and make new cover to fit this

The oplev beam path needs larger incident angle to get in and out of the chamber: REMOVE BOTTLENECK for easy traffic

Moving the existing table closer to ETMY chamber - as Jamie suggested-  would help but there is no room for this solution.

The larger table solve this issue and leave more room for initial pointing, arm transmitted and future experiments.

Other benefits: no tube to make between table and chamber. It is easier to make the the larger box air tight.

The new isolation box with feed through, cover, seals will cost $4-5K ea

 

 

Attachment 1: bottleneck.jpg
bottleneck.jpg
  7195   Wed Aug 15 16:29:59 2012 Eric SummaryGeneralSURF Update

This week I took more data for the calibration of YARM. The summary of measurements taken is:

1. Peak-to-peak on Michelson
2. Michelson open loop
3. Excite ITMY and measure on AS55_Q_ERR
4. Excite ITMY and measure on POY11_I_ERR
5. Excite ETMY and measure on POY11_I_ERR
6. YARM open loop

Then I worked on comparing these measurements to the Simulink model of the interferometer control loop. The measured open loop transfer function of the YARM matched well with the model above about 20 Hz, after the gain was scaled properly to fit the data. Next is to fit the length response function of the model and the measurements, and then use DTT to calibrate the arm cavity's power spectrum.

  7247   Wed Aug 22 01:54:03 2012 JenneUpdateGeneralList o' things: YarmASS, ETMXTcamera, POXwhiteningTriggering

While meditating on other things, I have noticed / found the following today:

YARM ASS works okay.  Yesterday I measured the sensing matrix for the ASS for both arms (although I forgot to copy one of the matrix elements to my text file for Xarm - needs remeasuring).  I put the Yarm matrix in (after appropriate inversion, only non-zero pitch-to-pitch, yaw-to-yaw elements).  I turned on the Yarm ASS, and  the yaw converged pretty quickly (couple of minutes), with gains of -1 in the servos, overall gain of anywhere between 0.005 and 0.010.  The pitch took much longer, and I had to 'pause' several times by turning off the overall gain for the yarm ass when the MC lost lock (which has happened several times tonight - unknown cause).  Eventually, the pitch settled out, and quit changing, but the lockin outputs weren't zero, even though the error signal for the servos were almost zero (gains for the pitch servos were -0.5, overall gain ~0.005 was better than 0.01 - higher gain caused oscillations in the lockin outputs).  I think this means that I need to remeasure the yarm pitch ass matrix.  It's still much, much faster to just turn on the dithers, watch the striptool of the lockin outputs, and align the cavity by hand.

I think the ETMX Trans camera view is clipped a little bit.  I went down there, and it doesn't seem to be on the last optic before the camera, and moving the spot on the camera doesn't change the shape of the image, so I don't think it's on the camera.  We should look into this, since it's either clipping on the BS that separates some camera beam from the TRX beam, or TRX is getting a clipped beam too.  If the clipping is any earlier in the Trans path, the Trans QPD could also have some clipping.  This requires investigation.  The xarm trigger needs to be reset/disabled so we don't lose lock every time we block the TRX beam (as was happening to me).

XARM really doesn't like to relock unless the POX whitening is turned off.  Good flashes, doesn't really catch (10+ min waiting (while working on Yarm stuff) ).  After turning off the whitening, it catches almost immediately. Even though it's on the to-do list to rethink the tuning of our whitening, we should probably implement the whitening triggering now anyway.  It'll make things easier.

The double integrator that Rana implemented in the X and Y arm servo filters last week take 8 seconds to turn off (due to Foton settings), so even though they are triggered to turn off immediately upon lockloss, they sit around and integrate for 8 seconds, so have huge signals.  If the cavity flashes and the locking trigger engages during that 8 seconds, we send a huge kick to the ETMs.  I'm modeling the response of the filters to an impulse and noise, particularly in the case of ramping on the double integrators.  The problem is that a flat filter has 0deg phase, but the double integrator has 180deg phase at low frequencies, so there's some weird sign flipping that can happen as we ramp - this is part of what I'm modeling.

MC is losing lock unusually often tonight.  Everything on the servo board screen looks normal (which is good since that's all set by the autolocker).  I just disabled the test exc in, but that's been left enabled for a while now, and it hasn't (I think?) been a problem since there shouldn't be anything connected to the board there.  PMC transmission is a little low, 0.816, and FSS is starting to get near -1 on the slow actuator adjust, but we've seen locking of the PMC problems around -1.5 or -2 of the FSS, and the adjust value was at -0.8 earlier tonight and we still had MC locking problems.  I have had the seismic channels open on Dataviewer for the last several hours, and I'm not seeing any spikes in any of the Guralp channels which correspond to the times that the MC loses lock.  BLRMS don't seem particularly high, so MC lockloss cause is still a mystery for today.

The ETMX monitor selector on the VIDEO screen seems not to be switching the actual camera that's shown on the monitor.  Using the script command itself works, so my screen is wrong.

  7248   Wed Aug 22 11:41:20 2012 steveUpdateGeneralgrout plate for optical table at the ends

Reinforced concrete grout plate for existing carbon steel stands at the ends.

 

Attachment 1: IMG_1561.JPG
IMG_1561.JPG
Attachment 2: 08231201.PDF
08231201.PDF
  7249   Wed Aug 22 15:47:34 2012 jamieSummaryGeneralvent prepartion for fast-track vent

We are discussing venting first thing next week, with the goal of
diagnosing what's going on in the PRC.

Reminder of the overall vent plan:

https://wiki-40m.ligo.caltech.edu/vent

Since we won't be prepared for tip-tilt installation (item 2), we should
focus most of the effort on diagnosing what's going on in the PRC.  Of
the other planned activities:

(1) dichroic mirror replacement for PR3 and SR3

  Given that we'll be working on the PRC, we might consider going ahead
  with this replacement, especially if the folding mirror becomes
  suspect for whatever reason.  In any case we should have the new
  mirrors ready to install, which means we should get the phase map
  measurements asap.

(3) black glass beam dumps:

  Install as time and manpower permits.  We need to make sure all needed
  components are baked and ready to install.

(4) OSEM mount screws:

  Delay until next vent.

(5) new periscope plate:

  Delay until next vent.

(6) cavity scattering measurement setup

  Delay until next vent.

  7255   Thu Aug 23 10:38:12 2012 SteveUpdateGeneralvent prepartion for fast-track vent

Quote:

We are discussing venting first thing next week, with the goal of
diagnosing what's going on in the PRC.

Reminder of the overall vent plan:

https://wiki-40m.ligo.caltech.edu/vent

Since we won't be prepared for tip-tilt installation (item 2), we should
focus most of the effort on diagnosing what's going on in the PRC.  Of
the other planned activities:

(1) dichroic mirror replacement for PR3 and SR3

  Given that we'll be working on the PRC, we might consider going ahead
  with this replacement, especially if the folding mirror becomes
  suspect for whatever reason.  In any case we should have the new
  mirrors ready to install, which means we should get the phase map
  measurements asap.

(3) black glass beam dumps:

  Install as time and manpower permits.  We need to make sure all needed
  components are baked and ready to install.

(4) OSEM mount screws:

  Delay until next vent.

(5) new periscope plate:

  Delay until next vent.

(6) cavity scattering measurement setup

  Delay until next vent.

 Bob is back. Cleaning and baking all our posts and clamps. They will be ready for use Tuesday next week. Therefore beam dumps will be available for installation.

  7271   Fri Aug 24 14:46:08 2012 JenneSummaryGeneralDetailed alignment plan

Friday / pre-vent:

[done] Align the MC mirrors for the incident beam so that the mirrors can be the alignment reference [Koji]

[in progress] Center spots on MC mirrors [Jenne]

Put beam attenuator optics (PBS + waveplate) on PSL table, realign input beam to MC mirror centers

[In progress] See if we can design a set of nuts and bolts to use at bottom of tiptilt optic ring, to do small adjustments of pitch alignment [Steve]

After doors open:

Use CCD (Watek, with AGC on) to take images of everything we can think of, to see current status of clipping

Check that we get through the Faraday without clipping

Move PZT1 and MMT mirrors to get good spot positions on PR3, PR2.  Make sure we're clearing the Faraday's housing

Install dichroic optics, perhaps completely readjust pitch alignment of those tiptilts (we will measure the spares later, and call that good enough for our phase mapping).

Use some kind of oplev setup to check pitch alignment of PR2, PR3.

Tweak (if necessary) PR2 & PR3 pitch to go through center of PRM, BS, hit center of ITMY

Check that we're not clipping on the BS cage anywhere

Use CCD to take images with Sensoray of everything we can think of, to confirm we don't have clipping anywhere.  Want to see the edges of the beam on the targets, which would mean that the beam is hitting the center of the optic.  If necessary, we'll stay open an extra day to get good camera images everywhere, so we have a good record of what's going on inside.

Note:  While having good arm alignment would be good, we're willing to sacrifice some arm alignment to have good DRMI alignment, since we're re-venting and installing the new active tiptilts in another month or so. 

Things I'm leaving for Jamie-the-Vent-Czar to plan:

Order of door opening

Beam dump assembly and placement

 

  7291   Tue Aug 28 00:16:19 2012 jamieUpdateGeneralAlignment and vent prep

I think we (Jenne, Jamie) are going to leave things for the night to give ourselves more time to prep for the vent tomorrow.

We still need to put in the PSL output beam attenuator, and then redo the MC alignment.

The AS spot is also indicating that we're clipping somewhere (see below).  We need to align things in the vertex and then check the centerings on the AP table.

So I think we're back on track and should be ready to vent by the end of the day tomorrow.

Attachment 1: as1.png
as1.png
  7296   Tue Aug 28 17:02:16 2012 jamieUpdateGeneralsvn commit changes

I just spent the last hour checking in a bunch of uncommitted changes to stuff in the SVN.  We need to be MUCH BETTER about this.  We must commit changes after we make them.  When multiple changes get mixed together there's no way to recover from one bad one.

  7314   Thu Aug 30 00:08:34 2012 jamieUpdateGeneralIn vac plans for tomorrow, 8/30

Quote:

We need to check spot centering on PRM with camera tomorrow.

Suresh checked that we're not clipped by IP ANG/POS pickoff mirrors, but we haven't done any alignment of IP ANG/POS.

 I think we should NOT do any adjustment of IP ANG/POS now.  We should in fact try to recover them when doing the PRM spot centering

Quote:

Tomorrow:  Open ITMX door.  Check with Watek that we're hitting center of PRM.  Then look to see if we're hitting center of PR2.  Then, continue through the chain of optics.

The motivation for removing the ITMX door was so that the scatter measurement team could check alignment of the new viewing mirror next to ETMX.  After discussion today we decided that everything can be done at the X end.  They can inject a probe beam into the ETMX chamber, bounce it off of ITMX and align the viewing mirror with the reflection.  So we'll leave ITMX door on for now.

We should, however, inspect the situation ITMY and make sure we have good clearance in the Y arm part of the Michaelson.  Koji previously expressed suspicion that we might have clipping on the southern edge of the POY steering mirror, so we need to check that out.

Koji and I discussed the situation for getting camera face views of BS and PRM.  Koji said the original idea was to see if we could install something at the south-east view port of ITMX chamber.  Steve also suggested utilizing the "ceiling" camera mounted on the top of the IOO chamber.

Vertex tasks:

  • check spot centering in PRM
  • check that REFL is getting cleanly to the AP table
  • check IPPOS and IPANG - we should be adjusting IPPOS or IPANG at this point
  • check spot centering on BS
  • remove ITMY north door
  • check clearance of POY steering mirror
  • ...

in parallel:

  • Steve will inspect the situation for getting a camera view of BS and PRM face, either through IOO or ITMX.

End X tasks:

  • install baffle
  • install "permanent" ITMX viewing mirror, on west side of ETMX - this might require moving ETMX SUS cable bracket south
  • install temporary steering mirror for probe laser on south-east side of ETMX
  • at some point the scatter guys can also do transmission measurements of the ETMX view ports
  • ...
  7315   Thu Aug 30 08:12:39 2012 SteveUpdateGeneralIn vac plans for tomorrow, 8/30

 

 1,PRM spot can be viewed directly from the window south-east of ITMX chamber.  I can easy set up the mobile- Watek for this reason or you can just use an IR viewer.

   Remember, we have 2 SOS centering targets ready to use , that Rana was suggesting.

2, PR2 spot centering can be viewed directly through window north-west of ITMX.

3, We should put back the BS view pick-up mirror for the vertical camera on the BS chamber and adjust its upper pick-up.

4, The BS centering can be viewed with the mobile-Watek placed inside the BS chamber immediately.

  7329   Fri Aug 31 17:26:54 2012 SteveUpdateGeneralBS camera

Steve and Eric

Placed pick up mirror for BS face and PRM back. I will ask Jamie to clamp it.

There will be an other camera set up to view the face of PRM

Attachment 1: BS_PRM.png
BS_PRM.png
  7335   Tue Sep 4 13:31:55 2012 JenneUpdateGeneralThe Plan

We need a plan for the rest of the week.  I want to be closing the heavy doors on Friday at the latest.  Please add to / comment on this list!

 

Tues

* Lock MICH to get BS, ITMs aligned well

* Check if beam is hitting center of ITMs. 

* Check for clipping around BS

     - Use Watek in-vac to look at beam at all 4 BS ports - make sure no clipping going into BS, after BS in the michelson, or the AS port

* Try to get arms to flash??

* Prepare glass beam dumps??

Wed

* IPPOS / IPANG - make sure beam gets out of chambers (this may require opening ETMY)

* Jan take photos of ETMX scattering setup

* Manasa take in-vac photos of all tables, for table layouts

* Jan / Manasa viewport transmission

* Install glass beam dumps?

* If ETMY open, install glass baffle

* ????

Thurs

* ????

* Check table levelling one last time on all tables. 

Fri

* Close all heavy doors.  (Access connector, ITMX, ITMY, BS, ETMX, ETMY? )

* Drag wipe test masses

* Start at ~10am?

Mon (if not Fri)

* Start pumping

  7336   Tue Sep 4 13:44:17 2012 ManasaUpdateGeneralThe Plan

Quote:

We need a plan for the rest of the week.  I want to be closing the heavy doors on Friday at the latest.  Please add to / comment on this list!

 

Tues

* Lock MICH to get BS, ITMs aligned well

* Check if beam is hitting center of ITMs. 

* Check for clipping around BS

     - Use Watek in-vac to look at beam at all 4 BS ports - make sure no clipping going into BS, after BS in the michelson, or the AS port

* Try to get arms to flash??

* Prepare glass beam dumps??

Wed

* IPPOS / IPANG - make sure beam gets out of chambers (this may require opening ETMY)

* Jan take photos of ETMX scattering setup

* Manasa take in-vac photos of all tables, for table layouts

* Install glass beam dumps?

* If ETMY open, install glass baffle

* ????

Thurs

* ????

* Check table levelling one last time on all tables. 

Fri

* Close all heavy doors.  (Access connector, ITMX, ITMY, BS, ETMX, ETMY? )

* Start at ~10am?

Mon (if not Fri)

* Start pumping

Wed

* Jan/Manasa - Measure transmission of viewport at ETMX

 

 

 

 

 

  7338   Tue Sep 4 20:03:38 2012 JenneUpdateGeneralin-vac progress

Opened ETMY, beam was high and to the right (if you look at the face of ETMY).  Tried walking beam up, since just doing PZT2 caused clipping at the BS before we got to the correct spot on ETMY.  Moved PZT1, then PZT2, to translate beam, but we couldn't get far enough without starting to fall off of PZT2.  Put PZT1 approx. back where it was. Jamie tapped on the top of PR3 (tip tilt just before BS), and then did some compensation with PZT2 to get the beam through the BS target to the center of ETMY.

The beam is very dim at ETMY.  We ended up holding the big IR card with holes such that one of the holes was near the center of the optic, in front of the cage.  Then one person turned off all the room lights so we could see the beam, another person moved PZT2 and PR3, then lights person turned on and off the lights so we could compare beam position with hole position.  A total pain, but it ended up working better than just trying to follow the beam with a card.

We clearly need a better plan for adjusting the tip tilts in pitch, because utilizing their hysteresis is ridiculous.  Koji and Steve are thinking up a set of options, but so far it seems as though all of those options should wait for our next "big" vent.  So for now, we have just done alignment by poking the tip tilt.

Tomorrow, we want to open up the MC doors, open up ETMY, and look to see where the beam is on the optic.  I am concerned that the hysteresis will relax over a long ( >1hour ) time scale, and we'll loose our pointing.  After that, we should touch the table enough to trip the BS, PRM optics, since Koji is concerned that perhaps the tip tilt will move in an earthquake.  Jamie mentioned that he had to poke the tip tilt a pretty reasonable amount to get it to change a noticeable amount at ETMY, so we suspect that an earthquake won't be a problem, but we will check anyway.

After doing all of that, we adjusted IPANG so that the beam gets out of the vacuum envelope.  The beam must squeeze between the wall of the black beam tube and a lens for the oplev, so there is a very, very limited amount of space.  The eventual new tables will be very helpful for alleviating this, but for now we must live with it.  Even though it is pretty squishy right at the edge of the table, with the new layout we should think about giving IPANG a little more space.  Basically, if there is any Yaw motion, the beam going to the QPD will be clipped, and we may get confusing info.  We moved some of the IPANG optics that are on the end transmission table so the beam is centered on the optics while it just makes it through the space between the wall and the lens.  The spot was centered on the IPANG QPD. 

We still need to check on IPPOS, but it is always easier than IPANG.

General notes:

We discovered that the 45deg SOS beam targets are awesome, especially the ones with the irises.  The plain hole ones have very small holes relative to our beam size, so they are much more useful for the MC optics (which they were designed for).  The 45deg targets were made such that the target holes do not line up with the mounting holes.  This is good, since the mounting holes are lower than the center of the optic.  I don't think ericQ and I realized that on Friday, so it's probable that we had installed the target upside-down.  We still need to remake the 0deg targets for the next vent.

Jamie dogged down the new 'bathroom mirror' that lets us see BS and PRM on the same camera view.  He also adjusted some of the masses on the BS table to relevel the table. We need to (at some point) rename the AS_SPARE camera to something like BS_PRM, since we plugged the new camera into the AS_SPARE port on the videoswitch.

tl;dr: Input beam adjusted so we're hitting center of ETMY.  IPANG coming out of vacuum, QPD centered. Need better tip tilt in-situ adjustment capability.

  7340   Tue Sep 4 20:13:46 2012 JenneUpdateGeneralThe Plan - Tues evening version

 Tues

* Hit center of ETMY, using input optics, PR3.

* Get IPANG out of vac, center QPD.

Wed

* AM: Riju do MC mode scans

* Starting right after 40m meeting, if not before: Lock MICH to get BS, ITMs aligned well

* Check if beam is hitting center of ITMX.

* Check for clipping around BS

     - Use Watek to look at beam at all 4 BS ports - make sure no clipping going into BS, after BS in the michelson, or the AS port

       - Use some old in-vac mirrors to direct beam out the BS door.  Cameras are waiting near BS chamber.

* Prepare glass beam dumps??

* IPPOS - make sure beam gets out of chamber

* Jan take photos of ETMX scattering setup

* Manasa take in-vac photos of all tables, for table layouts

* Jan / Manasa viewport transmission

* Install glass beam dumps?

* Install glass baffle at ETMY. Jan maybe install baffle at one of ITMs.

* ????

Thurs

* ????

* Check table levelling one last time on all tables. 

Fri

* Close all heavy doors.  (Access connector, ITMX, ITMY, BS, ETMX, ETMY? )

* Drag wipe test masses

* Start at ~10am?

Mon (if not Fri)

* Start pumping

  7341   Tue Sep 4 20:20:47 2012 jamieUpdateGeneralproblematic tip-tilts

Quote:

We clearly need a better plan for adjusting the tip tilts in pitch, because utilizing their hysteresis is ridiculous.  Koji and Steve are thinking up a set of options, but so far it seems as though all of those options should wait for our next "big" vent.  So for now, we have just done alignment by poking the tip tilt.

Tomorrow, we want to open up the MC doors, open up ETMY, and look to see where the beam is on the optic.  I am concerned that the hysteresis will relax over a long ( >1hour ) time scale, and we'll loose our pointing.  After that, we should touch the table enough to trip the BS, PRM optics, since Koji is concerned that perhaps the tip tilt will move in an earthquake.  Jamie mentioned that he had to poke the tip tilt a pretty reasonable amount to get it to change a noticeable amount at ETMY, so we suspect that an earthquake won't be a problem, but we will check anyway.

 I'm very unhappy with the tip-tilts right now.  The amount of hysteresis is ridiculous.  I have no confidence that they will stay pointing wherever we point them.  It's true I poked the top more than it would normally move, but I don't actually believe it wouldn't move in an earthquake.  Given how much hysteresis we're seeing, I expect it will just drift on it's own and we'll loose good pointing again.

And as a reminder, IPPOS/ANG don't help us here before the tip-tilts are in the PRC after the IP pointing sensors.

I think we need to look seriously at possible solutions to eliminate or at least reduce the hysteresis, by either adding weight, or thinner wire, or something.

  7346   Wed Sep 5 19:29:45 2012 JenneUpdateGeneralYarm aligned to IR incident beam

[EricQ, Jenne, brains of other people]

Checked at ETMY that the pointing hadn't changed a whole lot.  Jamie and Koji pointed out that we were half falling off of the IPANG QPD.  Adjusted PZT2 sliders so that we were again centered on IPANG's QPD.  Before we close up, we'll want to put the sliders back to their nominal positions, and use the knobs to hit IPANG, but this is equivalent and fine for now.  The tip tilts don't seem to have moved much overnight, since the beam drift on both IPANG and ETMY was fixed simultaneously with PZT2 (recall, IPANG picked off before tip tilts exist in the beam path).  This left us hitting the center of ETMY.  We moved ETMY sliders to make the reflected beam hit the center of ITMY (same spot position as transmitted beam from BS).  Then moved ITMY to get prompt reflection to hit same spot on ETMY as original primary beam from BS.  Checked at ITMY that we didn't need to move ETMY anymore.  (Actually, I forget how many iterations we did, but in the end, all of the reflections that we can find are co-located on the test masses.)

Next up:

Align BS so we're hitting the center of ETMX

Tap / readjust ITMX OSEM which is at 0.3 to get it back to the center of its range

Align ITMX to lock MICH

Check no clipping on POX / POY optics, no clipping around BS

Check PRM, SRM alignment (what exactly do we want to do here? Try to lock PRMI / SRMI?)

Get IPPOS out of vac

Fix clipped ITMY / SRM oplev

Install 'black' glass beam dumps - forward-going POP beam, 2 places in BS chamber (check old elog from Jenne/Yuta for the places).

Get green spots co-located with IR spots on ETMs, ITMs, check path of leakage through the arms, make sure both greens get out to PSL table

  7347   Thu Sep 6 02:51:47 2012 KojiUpdateGeneralGreen beam roughtly aligned (Re: Yarm aligned to IR incident beam)

The Y-End green beam was roughly aligned by the steering mirrors for the green beam.

I couldn't understand the Y-End green setup as the PD was turned off and the sign of the servo was flipped. Once they are fixed, I could lock the cavity with the green beams.

After a long alignment session, TEM00 was found. The alignment of the green beam has not been optimized.

Looking at the spot position at ETMY OSEM holders (not by the ccd image), it seems that the cavity mode is not at the center of the mirrors.

Quote:

[EricQ, Jenne, brains of other people]

Get green spots co-located with IR spots on ETMs, ITMs, check path of leakage through the arms, make sure both greens get out to PSL table

 

Attachment 1: green_y.png
green_y.png
  7348   Thu Sep 6 10:57:27 2012 JenneUpdateGeneralForgot to turn green refl pd back on

Quote:

I couldn't understand the Y-End green setup as the PD was turned off and the sign of the servo was flipped. Once they are fixed, I could lock the cavity with the green beams.

Quote:

[EricQ, Jenne, brains of other people]

Get green spots co-located with IR spots on ETMs, ITMs, check path of leakage through the arms, make sure both greens get out to PSL table

 

 I had turned the green refl PD off on Tuesday while we were doing the IPANG alignment, since the beam was not so bright, and the LED on top of the PD was very annoyingly bright.  I forgot to turn it back on.  The sign flip on the servo, I can't explain.

  7357   Fri Sep 7 01:25:53 2012 JenneUpdateGeneralPRC, SRC flashing

[Koji, Jenne]

* Found that IPANG was no longer centered, so we used PZT2's sliders to get the spot back on the center of the QPD.  Koji points out that I should have moved the lens even farther away, to have a larger beam (many mm, not just ~1) on the QPD.

* Found that MICH alignment had drifted, so used ITMX to realign MICH.

* Aligned PRM, got REFL beam through viewport.  Just made sure reflected beam was colinear with incident beam.

* PRC flashes were visible on AS camera. 

* PRM was more precisely aligned to have good interference with ITM reflections, by looking at AS camera.

* Decided to align SRM.  Spot was ~5mm too far to the north on the SRM....so we were off from center by ~5mm.

* Moved SR2 yaw a little bit to get spot centered on SRM.

*  Couldn't align SRM within bias slider range, so moved SRM in yaw to get reflected beam colinear with incident beam.

* Centered the spot on the steering mirrors.  The 2nd steering mirror after the SRM was moved by ~1 inch.  All mirrors after that were aligned to match this new beam.

* Found spot on AS table, aligned AS table mirrors so that beam hits AS55 PD window.  Haven't actually centered beam on PD.

* Transmission of 99% reflector was too weak to use with a card to get the beam back on the AS camera, so we moved the camera over to the AS110 path.

* Precisely aligned PRM and SRM by watching AS camera.

* Both the PRC and SRC look kind of funny.  Koji agrees.  Seriously.  They're a little weird. We can't align either recycling cavity, one ITM at a time (so PRM with ITMX, PRM with ITMY, SRM with either single ITM) to get rid of all the fringes.  Something is definitely funny.  It's got to be in the recycling cavities, since the weirdness is common between both ITMs for a given recycling mirror.  We need to take Sensoray views of these tomorrow.=

* There is some clipping on the right side of the AS camera view.  We have determined that it is not clipping at the viewport exiting the vacuum, but we aren't sure where it is.  It is at least before PZT4 (the 2nd PZT in the output AS path). 

  7367   Sat Sep 8 00:04:53 2012 JenneUpdateGeneralBeam scan measurement plan - to do Monday morning.

[MikeJ, Jenne]

We have a plan for how we're going to measure the beam after PR3.  Mike is going to write up a nifty program that will spit out the waist of the beam if you give it a bunch of razor blade measurement data.

Since the beam bounced off of the pitched ITMX is coming out of the chamber so high, it's kind of a pain to setup optics to steer the beam down the walkway next to the Yarm.  So, I have a new vision.

I think that we can get the beam right after PR3 onto the PRM/BS oplev table using 3 clean mirrors (of which we have many spares, already clean).  Once on the oplev table, we can put a 2" Y1 mirror to steer the beam down the walkway, after taking off the short east side of the table.  Then we can use the little breadboard on the mobile blue pedestal for the razor blade / power meter setup.

The razor blade on a micrometer translation stage will be the first thing on that table that the beam sees. Then, a 2" lens to get the beam small enough to fit on the power meter.  Then, obviously, the power meter.  We can measure the distance between the oplev table and the razor blade using the laser range finder, which has pretty good accuracy (it's sub-centimeter, but I don't remember the exact number for the precision).

A lens is not okay if we're trying to get the beam directly onto the beam scanner, since it will distort the beam.  However, as long as the razor blade is before the lens, and we're just using the lens to get the full intensity of the non-obscured part of the beam onto the power meter, I think using a lens should be fine.  If we don't / can't use a lens, we're going to run into the same problem we have with the beam scanner, since the power meters all have a fairly small aperture.  Even the big 30W power meter's aperture will be on the order of the size of the beam, so we won't be able to guarantee non-clippage.

The main problem I see with the technique as I have described it, is that the beam is going to hit 4 mirrors (3 in-vac, one outside) before going to the razor/lens/power meter.  We have to make sure that we're not clipping on any of those mirrors.  Also, this measurement version takes the beam after PRM, PR2 and PR3, but not after the BS and ITM.  I don't think we're concerned with either of those 2 optics, (especially since this is refl off the front of the BS, so won't see any potential clipping on the BS cage), but just in case we are, this measurement isn't so useful, and we'd have to come up with a different way of placing the mirrors on the in-vac tables to get a beam bounced off  of  a yaw-ed ITMX. 

Perhaps it would be easier to just go with the pitched ITMX version of the measurement, but I could use some ideas / advice on how to mount mirrors and lenses ~4 feet off the ground outside of the chambers, and not have them waving around on skinny sticks.

 

EDIT: Another idea is to instead use the beam transmitted through the BS, put a single clean steering mirror in the ITMY chamber, and get the beam out of the ITMY door.  This could either be the beam before the ITM, or we could yaw the ITM a little and take the reflected beam.

  7369   Mon Sep 10 08:50:35 2012 SteveUpdateGeneralBeam scan measurement plan - to do Monday morning.

 

 I misaligned ITMX pitch on Friday and brought out the beam at 44" height. The beam was bouncing to much. I only realized it this morning why. The OSEM voltages are 1.8, 1.7, 0.2 and 0.9V  Even with a stable 8-9 mm diameter beam you would be clipping

on the beam scanner 9 mm aperture. You can bring out the beam with one mirror right after  PR3, just remove  PRMOP2

  7371   Mon Sep 10 19:04:32 2012 ranaUpdateGeneralplan

 On Friday, Koji and I adjusted the beam pointing into the DRMI using the PZT yaw and found that the beam inside the DRMI (as seen on the AS camera) looked OK (not distorted too much).

So it seems that the issue seen before, namely that the DRMI resonant mode is very strange, is no longer true.

The camera image at the AS port still looks elliptical. So Jenne and Mike have started to make this beam round by adjusting the lenses.

Our plan now is:

1) Fix AS camera optics to get a round beam (single bounce off of ITMY).

2) Flash DRMI to make sure the beam at AS is still round.

3) Using the moveable Watec camera and Sensoray, get images of the spot on all DRMI mirrors with DRMI flashing. Use targets and rulers whenever possible to get quantitative measurements of the beam positions. (i.e. just saying "Oh, its pretty much in the center" is the Mickey Mouse approach to science)

4) Align all pickoff beams in this situation. Make sure there is no in vac clipping. Align IP POS and ANG using this input beam pointing.

5) Pump down.

 

  7378   Thu Sep 13 07:36:41 2012 SteveUpdateGeneralrestore conditions

Quote:

 Summary: Recorded the presence of higher order modes in IMC

What I did: Misaligned the flat mirror MC1 by small amount in both pitch and yaw (it was needed to be done cause at the beginning of the experiment no higher order modes were present)  and scanned the cavity for frequency-range 32MHz to 45MHz.

I found the presence of higher order modes around 36.7MHz (1st order)  and 40.6MHz (2nd order) along with two other strong modes near 35MHz and 42.5MHz.

 

 Please, restore condition after you finished and update elog right away! People wasted hours yesterday not knowing the condition of the MC

  7381   Thu Sep 13 23:27:14 2012 JenneUpdateGeneralPre-close checklist

We need to do the following things:  Images of optics in DRMI chain, place black glass beam dumps, make sure pickoff beams get out, align IP POS/ANG.

Black glass: behind MMT1, behind IPPOSSM3, forward-going POP beam.

Images and pickoff stuff should happen at the end of each vent.

Images need to be taken of the following optics (with ruler edge at center of optic):

* PZT1

* MMT1

* MMT2

* PZT2

* PRM

* PR2

* PR3

* BS (front and back?)

* ITMX

* ITMY

* SR3

* SR2

* SRM

* OM1

* OM2

* OM3

* OM4=PZT3

* OM5=PZT4

* OMPO

* OM6

* Viewport as AS beam leaves chamber

* POYM1 (check no clipping on edge of mount)

* POXM1 (check no clipping on edge of mount)

Pickoff / aux beams:

* REFL path

* POX

* POY

* POP

* IPPOS

* IPANG

  7383   Fri Sep 14 00:56:13 2012 JenneUpdateGeneralDRMI aligned

[Rana, Jenne]

We aligned the DRMI, and have concluded that it looks good enough that we should close up and pump down soon. We still need to use the camera to check things, and get all pickoff beams out of the chambers, so don't get too excited yet.

We looked at the mode matching telescope's calculated beam propagation, and since we're using spherical telescope mirrors at non-zero degree incidence angle, we expect an astigmatism about like what we are seeing on the AS camera.  This matches up with the measurements that Mike posted from his and Q's measurements earlier today.  We think that it has 'always' been this way, and someone just picked a camera position such that the beam used to look more round than it does now.

We aren't entirely sure what's up with the SRM - it almost looks like the pitch and yaw are coupled, but it was pretty easy to align the PRMI.  We don't see any evidence of the crazy, crappy beam that we did before the vent.  This means we have fixed most of the bad clipping problems we were seeing over the last ~year.

In the process of aligning the DRMI, we fixed up the input beam alignment - we were not hitting the exact centers of the MMT mirrors (in pitch, mostly), so we fixed that, and propagated the alignment fix through the chain.  In all, we touched the knobs on PZT1, MMT1, MMT2, PZT2.  The beam then went through the SRM, and we touched a few of the output steering mirrors to get the beam centered on all mirrors. 

I remeasured the MC spot positions, and they're a little worse than they have been.  Some of the spots seem to be off by 1.75mm (or less) on MC 1 and 3.  The numbers, MC1,2,3 pitch, then MC1,2,3 yaw are:   1.749759        9.744013        1.025681        -0.791683       -1.338786       -1.779958

A question to consider before doing the final-final alignment checking is: do we need to get the MC spots centered better than this, especially in light of the potential PMC axis having moved? 

  7388   Fri Sep 14 16:39:14 2012 ericq, jenneUpdateGeneralFirst In Vac Picture

After much fussing, we got a picture of MMT1 with the beam.

Using the iris doesn't seem feasible. Since it has to be significantly separated from the optic, it is hard to judge whether it is centered, especially in yaw.

It took ~30 min to get this picture. Comments on whether this kind of picture is good enough are welcomed, since there are many more to be taken.

Attachment 1: mmt1.jpg
mmt1.jpg
  7390   Fri Sep 14 18:18:33 2012 JenneUpdateGeneralIn Vac Pictures

Quote:

After much fussing, we got a picture of MMT1 with the beam.

Using the iris doesn't seem feasible. Since it has to be significantly separated from the optic, it is hard to judge whether it is centered, especially in yaw.

It took ~30 min to get this picture. Comments on whether this kind of picture is good enough are welcomed, since there are many more to be taken.

 I've been taking more photos.  Obviously, it gets quicker as I go along and get the hang of it.  Also, I've been taking overhead pictures with the Nikon so we can see what kind of parallax there is for each snapshot.

However, I just took MMT2, and the beam is nearly falling off the side of the optic!  It seemed fine last night when Rana and I were working on it.  The MC spots haven't moved significantly (I had measured yesterday, and again a few hours ago).  WTF?

This means that I need to move the knobs of MMT1, and then redo the whole alignment chain all over again.  Lame.

 

EDIT:  MC spot positions, last night at 12:33am, and this afternoon at 2:12pm:

                        year month day hour minute       MC1pit         MC2pit          MC3pit            MC1yaw         MC2yaw          MC3yaw

./data_spotMeasurements/MCdecenter201209140033.dat      1.749759        9.744013        1.025681        -0.791683       -1.338786       -1.779958      
./data_spotMeasurements/MCdecenter201209141412.dat      1.702974        7.916438        0.986519        -0.888736       -0.170237       -1.771267

 

Attachment 1: mmt2.jpg
mmt2.jpg
  7391   Fri Sep 14 18:28:25 2012 JenneUpdateGeneralIn Vac Pictures

All the photos so far:

PZT1:

pzt1_light.jpg

MMT1:

mmt1.jpg

MMT2:

mmt2.jpg

PZT2:

pzt2.jpg

IPPO:

ippo.jpg

  7393   Sat Sep 15 18:29:25 2012 JenneUpdateGeneralMore photos taken

{EricQ, Jenne]

More photos were taken.  Will post Monday, because too hungry now.

  7397   Mon Sep 17 13:39:32 2012 JenneUpdateGeneralMore photos taken

Quote:

{EricQ, Jenne]

More photos were taken.  Will post Monday, because too hungry now.

 Have eaten.  Here's a PDF with all the pictures to-date, along with a few notes.

Also, the first thing we did on Saturday was to fix the yaw pointing of MMT1, so that the beam hit the center of MMT2.  Then we had to touch PZT2 to compensate.  We put the iris target on the BS, and adjusted PZT2 until the beam went nicely through there.  The resulting beam looks good on the SRM, and teh beam is still hitting the AS camera.

Attachment 1: AllPhotos_Sept2012.pdf
AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf
  7399   Mon Sep 17 20:23:31 2012 JenneUpdateGeneralLast of In-vac mirror photos taken

[Manasa, Jenne]

We took the last of the in-vac photos of mirrors today.  I'll post in the morning.

Tomorrow, I'll align the DRMI once more to check, and get IPPOS and IPANG out of the vacuum.  I'll  take a look at POX, POY and POP, but we may just have to cross our fingers and hope for the best on those ones.  They were pretty hard to get out of the vac during their initial alignment, since they're so weak.

Also, tomorrow morning Steve is going to try out our new light access connector!!!!  I'm so excited!

The goal is to put heavy doors on, on Wed, and start pumping Wed afternoon / Thurs evening.

  7400   Mon Sep 17 23:58:01 2012 ranaUpdateGeneralLast of In-vac mirror photos taken

 My hope is that the DRMI flashes will be bright enough to see on the PO beams. IF we get 10 mW through the Faraday, you should get some buildup when the carrier resonates in the DRMI.

If the recycling gain is 10 and the pickoff fraction is 100 ppm you ought to get ~10 uW on PO. How much of the recycling cavity power gets out of POP?

  7401   Tue Sep 18 11:53:12 2012 JenneUpdateGeneralLast of In-vac mirror photos taken

Quote:

[Manasa, Jenne]

We took the last of the in-vac photos of mirrors today.  I'll post in the morning.

Tomorrow, I'll align the DRMI once more to check, and get IPPOS and IPANG out of the vacuum.  I'll  take a look at POX, POY and POP, but we may just have to cross our fingers and hope for the best on those ones.  They were pretty hard to get out of the vac during their initial alignment, since they're so weak.

Also, tomorrow morning Steve is going to try out our new light access connector!!!!  I'm so excited!

The goal is to put heavy doors on, on Wed, and start pumping Wed afternoon / Thurs evening.

 The photos on the OMC table are particularly tricky, since the camera plus the 'bathroom' mirror add a lot of weight....even if the MC locked, the input beam would be completely different, so all of the beams would be wrong.

During some of the work on the BS table, ITMY was realigned to have its beam retro-reflect, since the weight of the camera plus mirror was shifting all of the suspended optics on the BS table.  ITMY was restored after that, for subsequent photos.

Attachment 1: AllPhotos_Sept2012.pdf
AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf AllPhotos_Sept2012.pdf
  7402   Tue Sep 18 18:24:50 2012 JenneUpdateGeneralScattering in BS chamber or ITMX chamber

I have touched PZT2 such that the beam goes through the 45 degree non-iris target on the beam splitter.  This puts the beam at the center of ITMY, and without moving the BS, at the center of ITMX.  I say "at the center", but what I really mean is I put the target approximately at the center, within what looks like, say, 2 mm, by looking from above.  The target was many (5ish) centimeters away from the optic though, so that's why my side-to-side centering isn't so precise.  Given that, the beam was always more than half going through the hole of the target for both ITMs, so I'm claiming that the spots on the ITMs are within a few mm of center.

With this alignment, the beam was also hitting the center of the SRM (with all the same caveats).

I was able to get the SRM to retroreflect, while I still had Michelson fringing, so I think that I had the SRMI at least close to aligned (I was looking at the SRM retroreflection at the beam splitter, not all the way out to the AS port).  PRM is also pretty easy to align.

We're hitting the top of the AS camera, so I think things are pretty good.  I don't see beam on the REFL camera, but no investigation of that has been done as yet.

There is some scattering going on in the BS / ITMX chambers that's making me kind of unhappy.  I don't know how to get this to embed the youtube video, so here's the embed link, as well as the regular link:

youtube of AS and BS/PRM camera.

<iframe width="420" height="315" src="http://www.youtube.com/embed/QUbnMLXSS5U" frameborder="0" allowfullscreen></iframe>

Manasa watched the camera while I waved an IR card around in the BS chamber, and the only way I was able to get all the scatter spots to go away was to either block the beam incident on the BS (duh), or block the beam reflected off the BS, heading to ITMX.  Manasa said that the scatter spots still looked like they were fringing though, so I'm confused.  I may wave a card around in the ITMX chamber when I come back later tonight, to see what I can see.  Also, I just misaligned the SRM, and the scatter spots moved.  Now there's just some scatter off of what looks like the BS OSEM holders, as seen through the BS optic.

  7405   Wed Sep 19 01:08:48 2012 JenneUpdateGeneralDRMI aligned again

The DRMI was aligned once again tonight. 

Here's a video: http://youtu.be/Cy8nHL9yMeM  (Can someone please tell me / remind me how to make the elog embed videos?!?)

Description of video:

Video capture of AS camera.
NOTE: The beam is a few centimeters above ETMY with this alignment, so it will not be final.

Beginning is ITMY only.
ITMX is realigned to form MICH.
PRM is realigned to form PRMI.
SRM is realigned to form DRMI.
PRM is misaligned to form SRMI.
ITMX is misaligned to form SRY.

With this alignment, I opened up the ETMY door to find the beam there.  The beam is ~half on, ~half off of the top of the glass baffle.  Not the top of the hole, but the top of the piece of glass.  This means that it's many centimeters too high at ETMY.  This helps explain why, while swinging PZT2 around the other day, I could not see any beam on the cage.  It did, however, look pretty close (within a centimeter....I didn't look closer than that since it was so off in pitch) to centered yaw-wise.

Tomorrow I'd like a Clean assistant to help tweak PZT2 to hit the center of ETMY.  We'll need to put the 45 degree target back on to make sure that we don't end up pointing funny down the arm.  Then I'll realign the DRMI one more time.

Tonight, I can't check the full AS path, or any of the REFL path once it diverges from the main path.  Steve's new contraption (which is awesome!) doesn't have doors/windows yet, so I can't open it to get an IR card anywhere near any optics in the IOO or OMC chambers.  I waved PRM around a bit, but I can't find the beam on the REFL camera, so I definitely need to check that whole path again before we close up.

So, we're not closing up tomorrow, but progress has been made, and we're getting closer.

Note to self:  These are the ITMX, ITMY, PRM, BS, SRM biases with this DRMI alignment.  The DRMI is good, but the arms aren't, so these won't be final.  The saved alignments are still those with (for the Yarm) the beam bouncing several times between ITMY and ETMY.  BS was aligned at the time to hit the center of ETMX, and PRM and SRM should be retro reflecting in that alignment.  So, it's possible, that aligning PZT2 to hit the center of ETMY and restoring all of the optics will get me close to being back to DRMI aligned, but in a condition that the arms are align-able too.

Attachment 1: DRMI_aligned_19Sept2012_ETMYwasHighNeedToFix.png
DRMI_aligned_19Sept2012_ETMYwasHighNeedToFix.png
  7406   Wed Sep 19 01:15:15 2012 JenneUpdateGeneralLast of In-vac mirror photos taken - NOT!

I'm making a separate entry to go along with this thread of photos...

Putting the camera and 'bathroom' mirror on any table pretty significantly changes the leveling of any table.  The mirror especially is very heavy, although the camera is not feather light.  We need to come up with a new plan for taking alignment-confirming photos without adding anything to the tables.  That, or we have to level the table between each camera shot.  Anyone who has ever leveled one of our in-vac tables should shudder in horror at idea #2, so we need to put some thought into idea #1 before our next vent.  Vent Czar - can you put this on the list, in addition to the REFL rearrangement stuff?

As a result of this, PZT2 needed to be reverted to the place it was before work began on Saturday (so that the beam goes through the 45 degree target without any extra stuff on the table).  This means, unfortunately, that all of the photos / still captures of optics after PZT2 are invalid.

  7413   Wed Sep 19 19:38:37 2012 JenneUpdateGeneralSpot centered on BS, ETMY, ETMX

[Unni, Manasa, Jenne]

It turned out that the beam was a teeny bit high in the corner, so we touched PZT1 and PZT2 knobs to translate the beam down a bit.

Now the beam is centered on the BS (using the 45 degree non-iris target), centered on ETMY (using Steve's latest target, which worked perfectly), and then BS was aligned a tiny bit (really, it didn't need much) to get the beam centered on ETMX.

After dinner I'll align ITMX and ITMY such that their beams retroreflect and I get MICH fringes.  I'll also align SRM and PRM to retroreflect.  Check no clipping on AS path, get REFL path out, center IPPOS and IPANG, check POX, POY and POP.  Then, I think we might be almost done.

  7415   Thu Sep 20 01:28:14 2012 JenneUpdateGeneralDRMI aligned again, but with good arms

[Jenne, Manasa]

Using the alignment of the PZTs and BS from pre-dinner, where the beam was hitting the center of both ETMs, we aligned the DRMI.  The beam was off on the SRM in yaw by ~half a beam diameter, so I undid Koji's movement of SR2 from a week ago.  I loosened the SR2 dog clamps, touched it gently on the base to do a little bit of angle, then re-clamped it.  Once again, Steve's new brass centering target was awesome, since it was on the SRM while I was moving SR2. 

We approximately recentered the beam on the AS camera, although it didn't need much once we got the beam out of the vacuum, by centering it on all of the output AS path mirrors.

We also got IPPOS out of the vacuum.  Manasa was in the process of centering the QPD when the laptop died from too long being unplugged, so we leave that for tomorrow.

Left to do:

REFL path.  REFL is not coming out of the vacuum, and with the light access connector I can't reach any of the REFL steering mirrors, since they're in the center of the IOO table.

IPANG.  Should be easy.

POP, POX, POY.  Need to the the camera-on-a-stick back down to the corner (from ETMY) and point it at the pickoff mirrors to ensure that beam is getting out of the vacuum.

  7417   Thu Sep 20 08:34:46 2012 ManasaUpdateGeneralDRMI aligned again, but with good arms

Quote:

[Jenne, Manasa]

Using the alignment of the PZTs and BS from pre-dinner, where the beam was hitting the center of both ETMs, we aligned the DRMI.  The beam was off on the SRM in yaw by ~half a beam diameter, so I undid Koji's movement of SR2 from a week ago.  I loosened the SR2 dog clamps, touched it gently on the base to do a little bit of angle, then re-clamped it.  Once again, Steve's new brass centering target was awesome, since it was on the SRM while I was moving SR2. 

We approximately recentered the beam on the AS camera, although it didn't need much once we got the beam out of the vacuum, by centering it on all of the output AS path mirrors.

We also got IPPOS out of the vacuum.  Manasa was in the process of centering the QPD when the laptop died from too long being unplugged, so we leave that for tomorrow.

Left to do:

REFL path.  REFL is not coming out of the vacuum, and with the light access connector I can't reach any of the REFL steering mirrors, since they're in the center of the IOO table.

IPANG.  Should be easy.

POP, POX, POY.  Need to the the camera-on-a-stick back down to the corner (from ETMY) and point it at the pickoff mirrors to ensure that beam is getting out of the vacuum.

 Steve!! The light access connector got more ripped during the work last night...we've just taped it back. We might need  to figure out a better way to do this than just cutting through the cover.

  7419   Thu Sep 20 11:39:40 2012 ManasaUpdateGeneralDRMI aligned again, but with good arms

 

 QPD at IPPOS has been centered by removing the filter at the QPD.

So we need to remember to check back on AS camera path and the IPPOS as well in addition to the usual MCrefl path.

P.S. We would be happy to have a new laptop in the lab to replace "Belladonna"!

  7420   Thu Sep 20 14:55:06 2012 JenneUpdateGeneralPickoffs are hard to see

Quote:

 My hope is that the DRMI flashes will be bright enough to see on the PO beams. IF we get 10 mW through the Faraday, you should get some buildup when the carrier resonates in the DRMI.

If the recycling gain is 10 and the pickoff fraction is 100 ppm you ought to get ~10 uW on PO. How much of the recycling cavity power gets out of POP?

 [Manasa, Jenne]

We think this math is wrong.

If we have P mW through the Faraday, PRM's transmission is 5.5%, BS transmission is 50%, Recycling gain is ~10, pickoff fraction is ~100ppm, we have:

P mW * 5.5e-2 * 0.5 * 10 * 100e-6 = P * 2750e-8 mW = P * 2.7e-5 mW.

So, if P=10 (10mW through the Faraday), we should have 2.7e-4 mW = 2.7e-7 W = 0.27 microwatts = not so many watts.    

If P = 100 (100mW through the Faraday), we should have 2.7 microwatts. Still, not so many watts.

We have the Watec pointed at POY right now, DRMI is flashing, I'm waving the IR card in front of the mirror, and Manasa isn't able to see anything on the monitor.  The power into the vacuum is 100mW (we just measured and adjusted it), so even if we were getting a full 100mW through the Faraday, it would be hard to see.  If we're assuming we get ~half the power through the Faraday, then we should only have 1 microwatt

  7421   Thu Sep 20 17:05:26 2012 JenneUpdateGeneralREFL, IPANG are coming out of the vac

[Jenne, Unni, Manasa]

I touched some in-vac steering mirrors, so we have REFL and IPANG coming out of the vacuum, not clipping.  IPPOS was done yesterday.  I re-checked a few optics in the AS path that were hard to see yesterday while the plastic light access connector was in place, and AS still looks good.

Except for POX, POY, POP, and putting the regular EQ stops back on PRM, I think we're done with the in-vac stuff.

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