40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 61 of 341  Not logged in ELOG logo
ID Date Authorup Type Category Subject
  7444   Wed Sep 26 23:55:14 2012 JenneUpdateIOOWFS centered

Since the MC spots are good, I put the beam back on WFS 1 and WFS 2.

Also, I changed the indicators on the LockMC screen to reflect the change in elog 7289, where we added another on/off switch for the WFS so that the ASS could be on, but the WFS off.  For the last month, the WFS could be disabled, but the MC screen's indicators would suggest that we were pushing very significantly on all 3 MC mirrors.  Now the MC screen reflects reality a little better.

I also uncommented the WFS lines in the mcup script.  Den had commented them out, but didn't elog about it!  C'mon Den, please elog stuff!!!!  (He confessed out loud the other day, but it still wasn't in the elog).

I'm leaving the WFS loops disabled (even though the MC autolocker tries to turn them on, I have them manually disabled using the extra on/off switch) since they're unstable.  I'm in the process of figuring out what's wrong.  So far, the WFS improve the MC alignment for a minute or two, and then they totally misalign the MC.  This is a work in progress.

  7455   Mon Oct 1 11:08:25 2012 JenneUpdateIOOMC WFS adjustment

Quote:

Found a bug in the IOO screen: All of the 6 WFS signal indicators is liked to the same info (C1:IOO-MC1_PIT_OUTPUT).
Fix this, Jenne! Baaaaagghhhhh! 

 My bad.  As it turns out, you can't copy and paste between MEDM instances.  It is now fixed.

  7456   Mon Oct 1 13:11:43 2012 JenneUpdateIOOPZT inspection elogs

I'll come back to the PZTs later, but I want to write down all the elogs I have found so far that look relevant.

http://nodus.ligo.caltech.edu:8080/40m/699

http://nodus.ligo.caltech.edu:8080/40m/5368

nodus.ligo.caltech.edu:8080/40m/5431

  7465   Tue Oct 2 16:32:43 2012 JenneUpdateIOOPZT diagnosis

[Koji, Jenne]

Jamie and I pulled the whole PZT driver for both PZT1 and PZT2. 

Koji and I found that each HV power supply (the left-most module) has 2 fuses.  Both HV supplies (PZT1 and PZT2) have one blown fuse.  The "T2L250A" measures low resistance for both HV supplies, but the "T250mAL250V" measures Open for both HV supplies.

I have ordered 10 pieces of each kind of fuse, Next Day shipping, from DigiKey.

  7475   Thu Oct 4 01:06:52 2012 JenneUpdateIOOPZT diagnosis

[Koji, Jenne]

We naively hoped that just replacing the fuses would fix the problem with the PZT HV drivers.  Alas, this was not the case. 

All of our investigations (other than visual inspections) today have been of the PZT2 module.  We have not applied any electricity to any PZT1 components/modules today.

After blowing a few more fuses (not good, we know, but we really didn't know what was going on at the time and were convinced that our changes between fuse installations should prevent fuse-blowing, including removing all modules except the HV driver), we found that the YAW driver for both PZT1 and PZT2 has severe discoloration on the PCB, and several resistors and other solder joints are damaged near some high voltage regulators. Pitch on PZT1 looks a tiny bit discolored, but doesn't look totally cooked like the 2 YAW modules do.  So, at least PZT1's Yaw was cooked before we started replacing fuses, since we haven't plugged it in yet today.

We then began some more methodical checks:

We bypassed the fuses by applying 10 Vpp = ~7.2 Vrms to the input side of the big transformer on the PZT2 HV driver board.  (This usually sees the 120 Vrms from the wall AC, so we were looking at things with a factor ~16 attenuation from what they normally see.)  We then measured things on the other side of the transformer, and made sure that they made some sense (one path for 5V stuff, one path for 15V stuff, one path for 180V stuff).  One of the rectifying diode bridges (the one for HV) didn't seem to be working, and didn't seem to have all of its pins connected, as if perhaps one or more diodes inside was destroyed.

When I went home for dinner, Koji continued looking at the low voltage supply capability of the PZT2 driver.  He removed the diode bridge from the HV path, and also removed the FET that lives on the output side of the HV driver board.  He was then able to energize the HV driver and the non-burnt pitch module.  So the +\-5 V and +\-15 V paths have been confirmed okay for PZT2's driver stuff.

What I will do tomorrow (when there is someone here to rescue me if I crispy-fry myself) is solder a wire to the now open pin of the backplane connector on the HV driver board, so that we can supply an external 180V to the pitch / yaw modules (although, obviously we won't be using the burnt yaw modules as-is).  Tomorrow I'll start by applying a nice small voltage, check that things still look okay, no shorts, and then I'll slowly increase the voltage until I get to the nominal 180V.

Since the low voltage stuff on the driver board is working, once we supply an external 180V (if successful), we should be able to re-install the PZT driver and drive PZT2. 

Since both Yaw modules that we have are burnt, I am proposing that we use the PZT2 HV board (which has been checked and modified this evening) with the 2 pitch modules.  Since we are not actively utilizing the strain gauge sensors, the fact that the calibrations on these modules are not exactly the same (rather, that PZT1's pitch is not the same as PZT2's yaw) should not matter at all.  This means that we will not be able to energize PZT1 at all, but that shouldn't be a problem.  Even when PZT 2 was working, PZT1 had very, very, very limited motion through the full range of applied voltage, so having no driver connected shouldn't have an impact.

 

  7492   Fri Oct 5 14:53:29 2012 JenneUpdatePSLTTFSS board not fully seated!

[Den, Jenne]

Den noticed that the -15V LED on the TTFSS board was not illuminated.  A further symptom of the FSS being funny was that the PC RMS Drive was constantly high (3.6 ish) and the FAST Monitor was very high, often saturated. 

We took the TTFSS board out, and put an extender card in, and it looked like all of the correct power is being supplied to the board (the +\- 24V LEDs on the extender card were illuminated).  Just to check, we put the board back in, and this time both +\- 15V LEDs came on.  So it looks like the board is fine, it just wasn't seated in there all the way.

Now the readbacks on the FSS screen look good (PC RMS Drive is less than 1, FAST Mon is 5ish), the MC is locked, and I think we're back in business. 

 

  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.

  7501   Mon Oct 8 11:15:53 2012 JenneUpdatePSLPMC and FSS had a weird weekend

Something bizarre-o was going on with the PMC and FSS over the weekend.  On the striptool, PMC's PZT looks like it was doing a sawtooth pattern for several hours.  I opened up the FSS screen, and the FSS SLOWDC had walked itself up to +10.  It's not supposed to get that far from 0. 

Here are some trends, so you can see what was going on.

10 day trend:  This weird behavior began ~Friday evening (FSS_SLOWDC ramps quickly).

PMC_sawtooth_FSSweird_8Oct2012_10dayTrend.png

1 day trend:  You can see the sawtooth pattern in PMC_PZT more clearly here.  It's at the same time as the FSS_SLOWDC is ramping rapidly, and the FSS_FAST is saturated.

PMC_sawtooth_FSSweird_8Oct2012_1dayTrend.png

  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.

  7504   Mon Oct 8 14:19:17 2012 JenneUpdateIOOPZT diagnosis - not fixed yet

Quote:

What I will do tomorrow (when there is someone here to rescue me if I crispy-fry myself) is solder a wire to the now open pin of the backplane connector on the HV driver board, so that we can supply an external 180V to the pitch / yaw modules (although, obviously we won't be using the burnt yaw modules as-is).  Tomorrow I'll start by applying a nice small voltage, check that things still look okay, no shorts, and then I'll slowly increase the voltage until I get to the nominal 180V.

 I connected a thick wire to pin 22 of the backplane connector of the transformer / power supply module of the PZT box.  This is the pin that +180V is supposed to go on, to be distributed to the other boards in the crate.  Last week I had drilled a hole in the front panel so the wire can come out (since no one on campus seems to have HV panel mount connectors in stock). 

While the transformer module was isolated, not touching anything else, I applied (slowly ramping up) 180V DC, and it all looked good.

When I plugged the module back into the crate (first turning off and disconnecting the HV), I blew the 250mA fuse again.  No HV yet, just the low voltage stuff that Koji had fixed last week.  :( 

We're now out of 250mA fuses, we're supposed to get a box of them tomorrow.

  7505   Mon Oct 8 18:45:48 2012 JenneUpdateIOOPZT diagnosis - not fixed yet, possible solution

After the fuse-blowing fiasco earlier this afternoon, Koji and I took another look at the PZT controllers.

We put an ammeter in place of the fuse, and watched the current as we turned on the transformer module.  The steady-state current with no other modules plugged in is ~15mA.  However, there is a surge current right when you turn on the box which sometimes goes as high as 330mA.  Since the fuse is 250mA, this explains the fuse blowing, even though Koji had already checked out the low voltage path.

The high voltage line was connected, with +180V to the HV out pin of the backplane connector, and the (-) terminal of the power supply connected to signal ground on the board.

We inserted the PITCH module for PZT2, and we started with ~10V as our "high" voltage, and slowly increased the value (current at this time was ~60mA).  We also had a function generator plugged into the "MOD" input, which is where the epics slider goes, so that we should see a changing output voltage.  We never saw a changing output voltage.  Increasing the HV power supply didn't help. 

When Koji spun the "DC offset" knob really fast and then stopped, sometimes the output voltage as measured on the connector-converter board between the white and red wires would jump up, and then settle back down. It came back to the same value that it always was, but it was bizzarre that it would jump like that.  We suspect that that knob is an offset for use with the closed loop setting, so it isn't relevant for us anyway.  Watching the MON output, the value never changed, even when Koji did his fancy knob twirling.

We switched to the other PITCH module, and watched the output voltage on the MON output.  This time, with the function generator unplugged, so no modulation input (so we were expecting a steady DC output voltage) the number on the LCD and the MON output fluctuated wildly.  We plugged in the function generator, and the fluctuations did not change in approximate amplitude or DC offset.  They kind of looked the same. 

So, we have concluded that (a) the PZT drivers don't work, and (b) we don't understand why.  Therefore, we don't know how to fix them.

With that in mind, we are thinking of totally circumventing the PZT drivers. 

I plugged in the PZT1 connector converter board, which has Koji's circuit that he made last time when PZT1 died.  I plugged the ribbon cable which goes to the PZT, and the +\- 30V power supply, and the PZT responded!  Just plugging in the power supply puts the PZTs near the center of their nominal range.  I then put a function generator on the epics inputs for pitch and yaw (one at a time), and saw the spot move around at the ~1Hz that I was applying.  Yay!

What I think I'll do for tonight - modify the other connector converter board so that I can just use 2 HV power supplies (current limited) to steer the PZT.  I set up a TV monitor next to the PZT electronics (1Y3? 1Y4?  I forget), and it's connected to output 20 of the video switch, so I can watch the AS camera and move the PZTs by hand.  Then maybe I can try to align some stuff. (Evan is coming to work tonight, so if I electrocute myself, someone will be here to call 5000)  Koji suggested buying 2 single-channel thorlabs piezo drivers, like we have on the PSL table for the FSS loop.  These take in 0-10V and output either 0-75V, 0-100V or 0-150V (depending on which setting you choose).  These cost $712 each. This would be a more permanent solution than me just sitting out there, since we could once again control PZT2 via epics.

  7506   Mon Oct 8 21:42:17 2012 JenneUpdateIOOPZT diagnosis - not fixed yet, possible solution

Note to self:

The ENV-40 amplifiers that we have supply -10V through +150V .... so don't exceed those limits.

piezojena link

  7508   Mon Oct 8 23:58:57 2012 JenneUpdateSAFETYControl room emergency lights came on

[Evan, Jenne]

We were sitting trying to lock MICH (hooooorraaaayy!!!), and the emergency lights above the control room door came on, and then ~1 minute later turned off.  Steve, can you see what's up?

  7509   Tue Oct 9 00:25:33 2012 JenneUpdateIOOPZTs - hacky solution in place!!

[Evan, Jenne]

We applied some volts across both the pitch and yaw pin sets of the ribbon cable that goes to PZT2.  We ended up with ~40V yaw and ~14.5V pitch.  That was the nice happy center of the clipping that we can see on the AS camera.  Once we found the center of the PZT clipping range with the ITMY beam, we recentered the AS camera (actually, this took a few iterations, but now it's good). 

We then aligned MICH, but aren't able to get it to lock.  Before falling asleep, we have decided to align the PRM and SRM, so right now we have a flashing DRMI.  Both the SRMI and PRMI look a little funny the closer you get to 'good' alignment, so I'll investigate a little more tomorrow, and include pictures.  (The video capture script has barfed again, and I'm not in the mood to deal with it today.)

  7513   Tue Oct 9 23:12:56 2012 JenneUpdateLSC11MHz reconnected to EOM

Riju hasn't been in the lab in a long time to do any measurements, so I put the signals back to how they should be. 

I turned off / confirmed off the things which were sending signal to the EOM:  the network analyzer, the RF generator box, and the Marconi which supplies the 11MHz. 

I removed the cavity scanning cable, and terminated it, and put the regular 11MHz cable back on the splitter.

I then turned on the RF gen box and the Marconi.  The Marconi had been off, so we were not getting any 11MHz or 55MHz out of the RF gen. box.  This is why I couldn't lock any cavities last night (duh). 

On to locking!

----------------- In other news,

While swapping out the EOM cable, I noticed that the DC power supply sitting under the POX table was supplying a weird value, 17 point something volts.  I checked on the table to remind myself why that power supply is there...it's powering an RF amplifier right after the commercial PD that is acting as POP22.  The amplifier wants +15 and GND, so I reset the power supply to 15V.  We should add this to the list of things to fix, because it's dumb.  Either we need to put in the real POP22 (long term goal), or we need to get this guy some rack power, and do the same for any amplifiers for the Beat setup.  It's a little hoakey to have power supplies littering the lab.

  7514   Wed Oct 10 00:18:58 2012 JenneUpdateLockingREFL camera aligned

I moved some of the REFL optics on the AS table by a teeny bit to accomodate the new place that the REFL beam exits the chamber (none of this was done while we were at air....we were only dealing with the AS beam at the time, and were happy that REFL came out of the vacuum).

The REFL beam is now on the REFL camera (with PRMI aligned), and the beam is going toward the 4 REFL RF PDs, but it's not aligned to any of them.

I have some questions as to mystery optics on in the REFL path.  There is a 90% BS, and I don't know where the 10% reflection goes....is it going to beat against the AUX Stochino laser?

I have to go, and I didn't fix the videocapture script today, so pix tomorrow, I promise.

  7520   Wed Oct 10 15:46:23 2012 JenneUpdate cavitymode scan

Quote:

 Rijuparna, Jenne

Today I checked the optical lay-out in MC REFL board of the MC REFL path on the AS table (I will put the updated diagram in a few hours), and took a record of the reflected power of unlocked MC and power entering MC REFL PD. The power coming out of MC cavity when unlocked is 1.25W and power entering REFL PD 112mW (Jenne measured these powers for me). 

I also got a description of the MC demodulation board from Jenne.

(Edits by Jenne)

 Also, when I walked through the control room later, the WFS were driving the MC crazy.  I turned off / disabled the WFS from the WFS screen.   In my infinite spare time, I need to put in the real-time triggering, so that the WFS turn off as soon as the cavity unlocks. 

  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 :(

  7552   Mon Oct 15 22:24:45 2012 JenneUpdateComputersLots of new White :(

Evan and I are starting to lock, and there is lots of new, unfortunate white stuff on several different screens.

C1:TIM-PACIFIC_STRING is gone, C1:IFO-STATE (MC state) is gone, C1:LSC-PZT..._requests are gone (all 4 of them), C1:PSL-FSS_FASTSWEEPTEST from the FSS screen is gone (although I'm not sure that that one is newly gone), lots of the WF AA lights on the LSC screen are gone.

Those are the things I find in a few minutes of not really looking around.

EDIT:  IPPOS is also gone, so I can't see how my current alignment relates to old alignments.

  7554   Tue Oct 16 00:33:29 2012 JenneUpdateLSCPOP lens placed on POX table, 2 PRMI movies

[Evan, Jenne]

We aligned the PRMI.  We definitely can lock MICH, but we're not really sure if PRCL is really being locked or not.  I don't think it is.

Anyhow, we found 2 different places on the AS camera that we can align the PRMI.  One (middle, right hand side of the camera), we see the same weird fringing that we've been seeing for a week or two.  The other (lower left side of the camera), we see different fringing, almost reminds me more of back in the day a few months ago when the beam looked like it was expanding on each pass.  As I type, Evan is uploading the movies to youtube.  I *still* don't know how to embed youtube videos on the elog!

Also, we found both forward-going and backward-going POP beams coming out onto the POX table.  We placed the 2" lens in the path of the backwards beam, so that we can find it again.  We can't see it on an IR card, but if we put some foil where we think the beam should be, we can use a viewer to see the spot on the foil.  Poking a hole in the foil made an impromptu iris.

Youtube videos:

Lower left on camera

Middle right on camera

  7556   Tue Oct 16 11:38:17 2012 JenneUpdateLSCMore PRMI notes from last night

Quote:

How can you lock the PRMI without the REFL beams? c.f. this entry by Kiwamu
Which signals are you using for the locking?

I think the first priority is to find the fringes of the arms and lock them with POX/POY.

As for the POP, make sure the beam is not clipped because the in-vac steering mirrors
have been supposed to be too narrow to accommodate these two beams.

I was using AS55I for PRCL, and AS55Q for MICH.  I snuck that into the last line of an unrelated elog, since I did both things at the same time: see elog 7551.  Kiwamu's measurements (elog 6283) of the PRMI sensing matrix show that the PRCL and MICH signals are almost orthogonal in AS55 (although the optickle simulation doesn't agree with that...)  He was able to lock PRMI with AS55 I&Q (elog 6293), so I thought we should be able to as well.  Locking the PRMI was supposed to help tune the alignment of the PRM, not be the end goal of the night.  Also, we only tried locking PRCL in the "middle right" configuration, not the "lower left" configuration, but we were seeing what looked like recycling flashes only in the "lower left" configuration.

I agree in principle that we should be working on the arms. However, since we can't use the old steer-the-beam-onto-the-cage trick to find the beam, I was hoping that we could steer the beam around and see some light leaking out of the ETM, onto the end table.  However, with the 1% transmission of the ITMs and ~10ppm transmission of the ETMs, there's not a lot of light back there.  I was hoping to align the PRMI so that I get flashes with a gain of 10 if I'm lucky, rather than just the 5% transmission of the PRM.  With the PRMI aligned, I was expecting:

(1W  through Faraday) * (10 PR gain) * (0.5 BS transmission) * (0.01 ITM transmission) * (10ppm ETM transmission) = 0.5uW on the ETM tables during PRCL flashes

I was hoping that things would be well enough aligned that I could just go to the end table, and see the light with a viewer, although as I type this, I realize that if the beam was not on the end table (or even if it was...) any time I move the PZTs, I'd have to completely realign the PRMI in order to see the flashes.  This seems untenable, unless there are no other options.

We then got sidetracked by trying to see the POP beam, and once we saw the POP beam we wanted to put something down so we could find it again.  POP is also small, but not as small as expected at the end:

(1W  through Faraday) * (10 PR gain) * (20ppm PR2 transmission) = 0.2mW on POP during PRCL flashes.

POP was very difficult to see, and we were only able to see it by putting the foil in the beam path, and using a viewer.  I think that we once were able to see it by looking at a card with the viewer, but it's much easier with the foil.  I'd like to find an iris that is shiny (the regular black iris wasn't helpful), to facilitate this alignment.  Since we were just looking at the reflection off of the foil, I have no comment yet about clipping vs. not clipping.  I do think however that the forward-going beam may have been easier to find....when the PRMI alignment drifted, we lost the beam, but I could still see the forward-going beam.  Probably I should switch to that one, since that's the one that was lined up with the in-vac optics. 

Summary:

Ideas are welcome, for how to align the beam to the Yarm (and later to the Xarm), since our old techniques won't work.  Aligning the PRMI was a distraction, although in hopes of getting flashes so we could see some light at the end tables.  I'm going to go see if I can look through a viewport and see the edges of the black glass aperture, which will potentially be a replacement for the steering-on-the-cage technique, but if that doesn't work, I'm running out of ideas.

  7557   Tue Oct 16 11:54:05 2012 JenneUpdateIOOMC alignment??

The MC won't survive the boosts right now.  Pizza meeting is in a minute, and I won't be back to the lab before ~3:30 because of the seminar / a meeting, so someone else is welcome to try to fix it. Otherwise I'll have a look later on.

I'm leaving the autolocker disabled, so that it won't try any funny business.  WFS are off, so that they don't need to be turned off by the down script.

  7569   Wed Oct 17 18:41:27 2012 JenneUpdateCamerasCamera looking at ETMY baffle

The camera titled "watec_mobile" is looking at the front of the black glass baffle (i.e. the side facing the ITM) on the ETMY table.  This required (for my quick hacky solution) removing the regular ETMYF camera.  Steve has a genius plan (I think) so that we can have both at the same time.  Anyhow, eventually we'll move the black glass back, so we'll be back to needing just one camera.

After dinner, I'll try aligning the Yarm.

  7572   Thu Oct 18 03:45:56 2012 JenneUpdateIOOMCL, WFS triggers

Quote:

I've added MCL and WFS stop triggers into C1MCS/SUS model. Threshold value of MC_TRANS can be changed in the text entry located in MC2_POSITION medm screen. I tried 2 cases: trigger either blocks signal before MCL filter bank input or after output. Due to filter history in the 1 case MC2 was still slightly disturbed (C1:SUS-MC2_ULPD_VAR ~= 15) right after unlock. In the second case there was no disturbance as we zero output signal, but then I had to add "clear history" command to the mcup script.

WFS triggers block the signal before ASCPIT/YAW filter bank.

 I've redone the WFS triggers.  I left the MCL trigger alone (for now....I'll come back to it). 

The trigger was setup such that (a) it was totally unclear what was going on, by looking at the WFS screen.  Koji and I spent some time confused before I remembered that Den did this work recently.  Also, for some reason, the triggers were just plain thresholding, not a schmidt trigger, so any time the cavity flashed, the WFS came on.  Since the cavity can flash before the mcdown script has a chance to turn off the WFS servos, the outputs of the WFS filters are trying to output thousands of counts, and the signal goes through any time the cavity flashes.  Not so good.

I have removed the triggering for the angular DoFs from the mcs model (leaving the MCL triggering for now).  I have put new triggering into the ioo model, at the error point of the WFS loops.  The idea is that if the cavity unlocks, we don't want to lose the current pointing of the mirrors.  If the WFS servos were doing a lot of DC work, the bias sliders won't have the full information about where we want the mirrors to point.  Since we have the integrators in FM1, removing the input signal should freeze the output signal.  I need to modify the WFS on / off script so that this doesn't get turned off every lockloss.

Also, I have implemented (for the first time in a useful model, although I've done some testing in the tst model) the "wait" delay between a cavity locking and the trigger going through.  The idea is that we don't necessarily want the WFS to come on simultaneously with the cavity lock.  Since the wait delay resets any time it is un-triggered, this also prevents any signals from going through during cavity flashes.  The wait block has 3 inputs:  (1) a trigger, the output of some kind of trigger block, (2) a number of seconds to wait and (3) the model rate in Hz.  The model rate should be set with a constant in the model, the trigger passed from the trigger block, and the wait time in seconds should be available as an epics input. 

So far it looks like it's working as I expect, although I'm honestly too tired to do enough testing that I'm satisfied with, so I'm leaving the WFS off for the night.

  7573   Thu Oct 18 03:57:20 2012 JenneUpdateLockingAlignment is really bad??

The goal of the night was to lock the Y arm.  (Since that didn't happen, I moved on to fixing the WFS since they were hurting the MC)

I used the power supplies at 1Y4 to steer PZT2, and watched the face of the black glass baffle at ETMY.  (elog 7569 has notes re: camera work earlier)  When I am nearly at the end of the PZT range (+140V on the analog power supply, which I think is yaw), I can see the beam spot near the edge of the baffle's aperture.  Unfortunately, lower voltages move the spot away from the aperture, so I can't find the spot on the other side of the aperture and center it.  Since the max voltage for the PZTs is +150, I don't want to go too much farther.  I can't take a capture since the only working CCD I found is the one which won't talk to the Sensoray.  We need some more cameras....they're already on Steve's list.

When the spot is a little closer to the center of the aperture than the edge of the aperture (so the full +150V!!), I don't see any beam coming out of AS....no beam out of the chamber at all, not just no beam on the camera.  Crapstick.  This is not good.  I'm not really sure how we (I?) screwed up this thoroughly.  Sigh.  Whatever ghost REFL beam that Kiwamu and Koji found last week is still coming out of REFL.

Previous PZT voltages, before tonight's steering:  +32V on analog power supply, +14.7 on digital.  This is the place that the PRMI has been aligned to the past week or so.

Next, just to see what happens, I think I might install a camera looking at the back (output) side of the Faraday so that I can steer PRM until the reflected beam is going back through the Faraday.  Team K&K did this with viewers and mirrors, so it'll be more convenient to just have a camera.

Advice welcome.

  7577   Fri Oct 19 00:55:35 2012 JenneUpdateComputersc1lsc is down (at least all of the models)

When Evan and I were dithering the BS and ITMY (see his elog), I noticed that c1lsc was acting weird.  the IOP was the only one with the blinky heartbeat.  The IOP was all green lights, but all the other models had red for the fb connection, as well as the rightmost indicator (I don't know what that one is for).  I logged on to c1lsc and ran 'rtcds restart all'.  The script didn't get anywhere beyond saying it was beginning to stop the 1st model (sup, the bottom one on the lsc list).  Then all of the cpus went white.  I can still ping c1lsc, but I can't ssh to it.

I'm not sure what to do here Jamie.  Heelp. 

  7578   Fri Oct 19 01:11:18 2012 JenneUpdateIOOMCL, WFS triggers

Quote:

Quote:

 

 I've redone the WFS triggers.  I left the MCL trigger alone (for now....I'll come back to it). 

The trigger was setup such that (a) it was totally unclear what was going on, by looking at the WFS screen.  Koji and I spent some time confused before I remembered that Den did this work recently.  Also, for some reason, the triggers were just plain thresholding, not a schmidt trigger, so any time the cavity flashed, the WFS came on.  Since the cavity can flash before the mcdown script has a chance to turn off the WFS servos, the outputs of the WFS filters are trying to output thousands of counts, and the signal goes through any time the cavity flashes.  Not so good.

 Your schmitt trigger has 2 threshold values - min and max. Set thresholding value in my trigger to the max of your schmitt trigger and you get the same behavior for MC,  triggers are not supposed to turn anything on in this realization as they do for locking with flashing.

 The problem is that the WFS were being engaged with your triggers every time the MC flashed.  That wasn't a schmidt trigger thing, but I like the schmidt trigger better anyway.

 

Anyhow, it's turned on, and it works really well.  It's kind of awesome.  I'm really excited to start using the wait block to start pushing even more of the locking out of scripts and into the real time system.

  7584   Fri Oct 19 19:26:42 2012 JenneUpdateVACvent has started

Quote:

Quote:

 

 PSL shutter closed, manual block in place, HV turned off. P1 is at 200 Torr now.  Jenne is taking over here.

 Valves closed, 500 torr.  Steve will finish off Monday morning, then we'll take off doors and get to work.

  7590   Mon Oct 22 21:20:36 2012 JenneUpdatePSLBeam attenuation optics in place

[Jenne, Raji (before dinner)]

We put the beam attenuation optics in place.  Before putting any optics down, I centered the IOO QPDs, then adjusted the HWPs and PBS such that we remained centered on those QPDs.

Now, I'm about to unblock the beam and let ~100mW into the vacuum so I can lock the MC.  Steve and Manasa were putting on the light access connector when I left earlier, so I'm excited to use it!

  7591   Tue Oct 23 00:41:55 2012 JenneUpdateAlignmentMC locked, spots centered

[Jenne, Raji]

We replaced the MC Refl path BS with the Y1, as usual, so that the full ~100mW goes to the REFL PD, so we don't have WFS or MC refl camera. 

The MC spots were all outside of 1mm, and some were beyond 2mm (for MC1,3, P,Y....MC2 is of course free since we have more DoFs than we need), so we touched (very, very slightly) the zigzag mirrors on the PSL table.  We realigned the MC, and now the spots are centered to my satisfaction.

MC1,2,3 Pit,    MC1,2,3 Yaw (in mm):

[0.46444020918749457, 8.2634316545130009, -0.41417975237831089, -0.89401481457980592, -0.9323196976382162, -1.543145765853893]

MC2 is way off in pitch, according to this measurement, and it's been consistently going down as we move the MC2 spot in the same direction (up on the monitor), but since we started at +15mm and are now at +8, and we've gone quite a ways, I'm not sure that we really want to go all the way to 0.  Anyhow, MC1 and MC3 are the ones which define our input pointing, so we're quitting for tonight.

We will turn on the PZTs and begin with the official vent list for dummies tomorrow.

  7601   Tue Oct 23 18:12:18 2012 JenneUpdateAlignmentTip tilt wires - the truth

Quote:

At this point I cried foul.  This is not an acceptable situation.  Very little stimulation to the tip-tilts can repoint the beam inside the PR cavity.

Steve says that the TT weights, which will attach to the base of the TT mirror mounts and should help keep the mirrors vertical and not hysteretic, are being baked now and should be available tomorrow. 

 We also wrote down the serial numbers (top center of each TT, inscribed by hand) for what tip tilt is installed where.  I then went through the elog to determine which TT was suspended with what kind of wire (thick or thin).  Summary: all installed tip tilts have thick wire, 0.0036" diameter.

As noted in elog 3295, we had found that there was similar hysteresis whether we used the thick or the thin wire, so we had decided not to go back and re-suspend every optic.

Also, since we will redo the pitch balance tomorrow with the new hardware tomorrow, I think we should put in the new LaserOptik mirrors at the same time.  We have not yet gotten phase maps of them, but we might as well do this rebalancing once, rather than twice.

 

As-installed tip tilt list
Serial number Installed as Wire thickness Notes, elog reference
001 SR 3 0.0036" See elog 3437
002 SR 2 0.0036" See elog 3295
003 PR 2 0.0036" No elog, but inferred since there were 4 with thick wire, and #004 is the thin wire one.  Elog 3437 has notes on the 4 thick, 1 thin situation.
004 spare, dirty originally 0.0017", but looks redone with thicker wire See elog 3295
005 PR 3 0.0036" Was supposed to be spare according to elog 3437, but was installed.  See elog 3437

 

  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.

  7603   Tue Oct 23 18:21:21 2012 JenneUpdateAlignmentPower supply at OMC removed

Quote:

Quote:

Manasa and Raji hooked up HV power supplies to the PZTs and set them to the middle of their ranges (75 V).

 [Raji, Manasa]

The high-voltage power supply from the OMC was removed to replace one of the PZT power supplies. The power supply terminals were connected to the rear connection ports as per instructions from the manual (TB1 panel: port 3 - (-)OUT and port7 - (+)OUT). They were both switched  on and set to deliver (75V) to the PZTs.

 

 This means that the low voltage dual supply which was wired in series (so could supply a max of 63V = 2*31.5V) has been replaced with the OMC power supply.  This is okay since we haven't turned on the OMC PZTs in a long, long time.  This is *not* the power supply for the output pointing PZTs.  When she says "both", she means the new HV supply, as well as the HV supply that was already there, so both pitch and yaw for PZT2 are being supplied with 75V now.

  7606   Wed Oct 24 11:49:07 2012 JenneUpdateAlignmentGame plan for the day

Jamie has arranged for phase map measurements this afternoon, so I will take the 6 dichroic LaserOptik optics over to Downs at 1:15 this afternoon.

Team Jamie+Nic will lead the effort to clamp down dog clamps as placement markers for all 4 in-vac passive TTs, and then pull all 4 TTs out of the chambers.  They plus Den will move the TTs to the Cleanroom, and will start to install the new pitch alignment hardware. 

When I return with the optics, we will install them in the TTs and re-balance them.  Then we can put them back in the chambers and get back to work on alignment.  

After we re-install the TTs, we will need to check the leveling of all 3 corner tables, just to be sure.

  7608   Wed Oct 24 14:19:01 2012 JenneUpdateAlignmentPhase map summary of LaserOptik mirrors

Quote:

Jamie has arranged for phase map measurements this afternoon, so I will take the 6 dichroic LaserOptik optics over to Downs at 1:15 this afternoon.

Team Jamie+Nic will lead the effort to clamp down dog clamps as placement markers for all 4 in-vac passive TTs, and then pull all 4 TTs out of the chambers.  They plus Den will move the TTs to the Cleanroom, and will start to install the new pitch alignment hardware. 

When I return with the optics, we will install them in the TTs and re-balance them.  Then we can put them back in the chambers and get back to work on alignment.  

After we re-install the TTs, we will need to check the leveling of all 3 corner tables, just to be sure.

 Raji took the optics over. They were all measured at 0 deg incidence angle, although we will use them at the angles required for the recycling folding mirrors.  Here's the summary from GariLynn:

In general all six pieces have a radius of curvature of around -700 meters.

They all fall off rapidly past 40 mm diameter.  Within the 40 mm diameter the rms is ~10 nm for most.  I can get finer analysis if you have something specific that you want to know. 
 
All data are saved in Wyko format at the following location:
Gari
  7610   Wed Oct 24 17:02:01 2012 JenneUpdateAdaptive Filteringmicrophone noise

Quote:

  We have to change the sample rate and AA filter for the mic channels before going too far with the circuit design.

 To save the mic channels at higher than 2k (which we should do), we either have to move them to a different model, change the rate of the PEM model, or see if you can save data faster than the model runs (which I can't imagine is possible).

  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.

  7631   Fri Oct 26 13:08:14 2012 JenneUpdateSUSTip tilts in progress

Quote:

Quote:
 

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.

 The tip tilts have all been pitch-adjusted now, and they have all been put back onto the tables, with the same serial numbers in the same places as we took them out.  Jamie also re-leveled the BS table.

Raji and I will align things after I finish measuring the MC spot positions.

  7632   Fri Oct 26 16:57:30 2012 JenneUpdateAlignmentPR2 aligned, PR3 mostly aligned

[Raji, Jenne]

After lunch we began where Raji and Jamie had left things.  PR2 was unfortunately pitched down so far that it was almost hitting the table just in front of PR3.  I loosened the 4 clamp screws that hold the wire clamp assembly to the mirror holder, and tapped it back and forth until I was within hysteresis range, re-tightened, then tapped the top and bottom until we were at the correct beam height just in front of PR3.  I also had to unclamp it from the table and twist the base a tiny bit, since the beam was closer to hitting the beam tube than the optic.  Finally, however, PR2 is adjusted such that the beam hits the center of PR3.

Moving on to PR3, the pitch looked good while we were looking at the aperture placed near the face of ITMY, so we left that alone.  The beam is off in yaw though.  Several times I unclamped the tip tilt from the table, and twisted it one way or another, but every time when I tighten the dog clamps, I'm too far off in yaw.  The beam points a little too far south of the center of ITMY, so we were putting the beam a little north of the center before I clamped it, but even tightening the screws in the same order, by the same amount each time, causes a different amount of slipping/twisting/something of the TT mount, so we never end up directly in the center of the ITM.  It seems a little like a stochastic process, and we just need to do it a few more times until we get it right. 

We left it clamped to the table, but not in it's final place, and left for JClub.  On Monday morning we need to go back to it.  As long as we're pretty close to centered, we should probably also have someone at ETMY checking the centering, because we need to be centered in both ITMY and ETMY.

We have not touched the SR tip tilts, so those will obviously need some attention when we get to that point.

  7641   Mon Oct 29 18:50:02 2012 JenneUpdateAlignmentPRC aligned, Yarm almost aligned

[Jamie, Jenne, Raji, with consultation from Nic, Ayaka and Manasa]

We went back and re-looked at the input alignment, and now we're "satisfied for the moment" (quote from Jamie) with the PRC alignment.  Also, by adjusting the PR folding mirrors, we are almost perfectly aligned to the Yarm.

What we did:

Set PRM DC biases to 0 for both pitch and yaw.

Aperture was attached to PRM cage, double aperture was attached to BS cage, free-standing aperture was placed in front of PR2. 

Adjusted PZT1, PZT2 such that we were centered on PZT2, and through apertures at PRM and PR2.   This was mainly for setting beam height in PRC.

Checked centering on PZT1, MMT1, MMT2, PZT2.

Adjusted PRM pitch bias and PZT2 yaw such that REFL beam was retro-reflected from PRM.

Checked that REFL beam came nicely out of Faraday.

Checked that beam was still going through center of PRM aperture, and pitch height at PR2 was good.

Moved PR2 sideways until beam hit center in yaw of PR2.

Twisted PR2 such that beam was hitting center of PR3.

Moved and twisted PR3 (many times) so that beam went through BS input and output apertures, and through center of ITMY aperture.

Found that beam was just getting through black glass aperture at ETMY, top left corner, if looking at the face of ETM from ITM.

Locked down dog clamps on PR2.

This required some re-adjustment of PR3.  Re-did making sure going through BS apertures and ITMY aperture, locked down PR3 dog clamps.

Found that we are centered in yaw at ETMY, a little high in pitch on ETMY.

Replaced all of the light doors, to take a break.  4 hours in bunny suits seemed like enough that we earned a break.

This all sounds more straighforward than it was.  There was a lot of iteration, but we finally got to a state that we were relatively happy with.

 

What we will do:

Tweak PZT2 a *tiny* bit in pitch, ~0.5 mrad, so that the beam goes through the ETMY aperture.

See if we can align EMTY and ITMY to get multiple bounces through the Yarm.

Remove ETMX heavy door, steer BS such that we're getting through the center of an aperture at ETMX.

Align ETMX and ITMX such that we get multiple bounces through the Xarm.

Check SRM, AS path alignment.

Check REFL out of vac alignment.

Check other pickoffs.

Check all oplevs.

Check IPPOS/IPANG

 

We have a open-sided 2" mirror mount that we are considering using for the POY pick-off mirror.  This might help us get a little more clearance in the Y-arm of the Michelson.  Problem is the mount is not steerable, so we need to determine if that's doable or not.

 

  7642   Tue Oct 30 11:51:45 2012 JenneUpdateAlignmentPRC aligned, Yarm almost aligned

[Raji, Jenne]

We tweaked PZT2, PZT1 (yaw only), and PR3 (pitch only) to get the beam ~centered on the BS aperture, the ITMY aperture, and the ETMY aperture.

After lunch I'll tweak up the MC alignment, since, although the spots are in the right places, the transmitted beam could be higher power.  This will make it easier to check our pointing, especially since the ETMY spot is larger than our aperture, but the beam is dim.

We're getting there!

  7647   Wed Oct 31 17:18:34 2012 JenneUpdateAlignmentprogress, then setback - trend of BS table shift

Here is a two hour set of second trends of 2 sensors per mirror, for BS, PRM, ITMY and MC1.  You can see about an hour ago there was a big change in the BS and PRM suspensions, but not in the ITMY and MC1 suspensions.  This corresponds as best we can tell with the time that Jamie was figuring out and then fixing PZT2's mount.  You can see that the table takes some time to relax back to it's original position.  Also, interestingly, after we put the doors on ~10 or 20 minutes ago, things change a little bit on all tables. This is a little disconcerting, although it's not a huge change.

  7658   Thu Nov 1 19:28:48 2012 JenneUpdateAlignmentaligned, AS beam on camera

After everyone else did the hard work, I moved the AS first-on-the-table steering mirror sideways a bit so the AS beam is on the center of the mirror, then steered the beam through the center of the lens, onto the 2" 99% BS.  I also moved the camera from it's normal place (the 1% transmitted through that BS) to the AS110 PD path, as we did last vent.  We'll need to put it back before we go back to high power.

  7662   Fri Nov 2 14:37:36 2012 JenneUpdateGeneralOpen-sided mount - why

Quote:

Quote:

Suprema- SS clear edge mirror mount 2" diameter is modified for 40m vacuum use. One left and one right handed one. It's adjustment screw housing is bronze! It is not ideal for out gassing.

It will be baked and scanned. If it passes we should use it.

We may need these to bring out some pick-off beams.

 I vote against it. We don't know about the grease inside the screw bushings - scans are not everything if adjusting the screw loosens up the grease. If we need more pick off mirrors lets just make some of the kind that we already use inside for the 2" optics.

 I think Steve had these prepared in response to my question a few days ago of how badly do we need adjustability for the POX/POY mirrors?  We already have cleaned open-sided mounts that have no adjustment screws.  So as long as the beam reflects off the ITMs horizontally (which it should), we can do yaw adjustment by twisting the whole mount. We don't need super fine yaw adjustment, we just need to get the beam out, so this is probably good enough.

We should put the POY mirror on this open-sided mount (the one without screws) some time.  Perhaps even today.

  7664   Fri Nov 2 19:59:54 2012 JenneUpdateAlignmentPOP, POX, POY, IPPOS, IPANG, REFL all coming out of vac

[Evan, Jenne, Jamie]

We used the green laser pointer technique to adjust the POP steering mirrors behind PR2 to get the POP backward beam out onto the table (rather, the mirrors were adjusted so that the green laser pointer, mounted on the POX table, was co-aligned with the beam between PR2 and PR3).

We were unable (why? I feel like it wasn't so hard last time) to see the POX beam, with a camera pointed at an IR card.  We ended up just waving a lens-free CCD camera around on the POX table where we expected POX to be, found the beam, and decided that if the beam was getting to the table, that was good enough.

We then waved the camera around on the POY table, and found the POY beam on the table.  We also moved ITMY up and down in pitch, and saw that the POY beam was moving, so we were satisfied that we had the correct beam.  We should go back and do this same check with POX, although I'm pretty sure that we already have the correct beam.  But checking is good.

We confirmed that IPPOS was coming out of the chambers.  I didn't end up touching any in-vac mirrors for IPPOS, since they all looked centered, and the beam on the table was already centered on the steering mirror on the out-of-vac table.

We got IPANG out of the chamber to the ETMY table.  IPANG has, after the pickoff window, an adjustable mirror, and then a fixed mirror on the BS table.  The beam was very close to the edge, in yaw, on that fixed mirror.  Jamie unclamped it and moved it so the beam was centered, then twisted it until I got beam back down at the end, centered on the first steering mirror down there.  Then Evan and I got the beam centered on the other steering mirror on the in-vac ETMY table, and got the mirror to ~the center of the first out-of-vac steering mirror.  Then Evan adjusted the other steering optics so the beam was hitting the QPD.

We then got the real REFL beam out of the chambers.  I still don't know what that ghost/fake beam is.  Anyhow, we moved PRM around, and saw that the real REFL beam moves, while the fake one doesn't.  We adjusted the adjustable REFL steering mirror in-vac such that the real REFL beam came out to the table.  Once on the AP table, we moved the PRM around again, just to be doubly/triply sure that we had the correct beam.  We put a beam splitter (found on the SP table) after the lens in the REFL path on the AP table, and put the camera on the reflected side of that BS.  This is because, like the AS port, the beam is too dim at the normal camera spot (which for REFL is the transmission through a Y1 mirror).

Jamie has centered IPPOS and IPPANG QPDs, so we should look at the weekend trend come Monday, to see what things look like, and how they drift, if at all.

 

On Monday, we should:

* Check the alignment, and the centering of beams on all mirrors one last time

* Remove all apertures from suspended optics (I think BS and PRM may be the only two that have them at this time)

* Check oplev paths for all mirrors

* Check all pickoffs / beams that need to come out of the vacuum

* Start putting on doors

  7665   Fri Nov 2 20:41:53 2012 JenneUpdateAlignmentAS, REFL camera shots

These don't show anything too interesting, but we're including them to show where the beams are right now on the cameras, so we can compare on Monday.

 

AS:

AS_2Nov2012.png

 

REFL:

REFL_2Nov2012.png

 

 

  7668   Mon Nov 5 09:53:35 2012 JenneUpdateAlignmentAS, REFL camera shots

Today's photos:

AS:

AS_5Nov2012.png

 REFL:

REFL_5Nov2012.png

IPANG / IPPOS trends:

IPPOS_IPANG_weekend_trend.png

 

 c.f. screen caps from Friday:

Quote:

These don't show anything too interesting, but we're including them to show where the beams are right now on the cameras, so we can compare on Monday.

 

AS:

AS_2Nov2012.png

 

REFL:

REFL_2Nov2012.png

 

 

 

  7683   Wed Nov 7 15:51:44 2012 JenneUpdateAlignmentJamie's tip tilt proposal

Steve's elog 7682 is in response to the conversation we had at group meeting re: Jamie's proposed idea of re-purposing the active tip tilts.

What if we use the active TTs for the PR and SR folding mirrors, and use something else (like the picomotors that Steve found from the old days) for our input steering?

ELOG V3.1.3-