40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Authorup Type Category Subject
  8962   Fri Aug 2 22:51:10 2013 JenneUpdateGeneralAll vent tasks complete, just need oplev check

[Manasa, Koji, Jenne]

We went into the BS and IOO chambers, and aligned the green beams such that they came out of the vacuum chamber.  The idea here was to get the beams at the same height, but slightly offset in yaw.  This required moving the Periscope on BS table, PBS in front of that periscope, the Periscope on the IOO table, and 2 steering mirrors on the IOO table after the 2nd periscope.  The tables were not releveled, although we have aligned the full interferometer to this situation, so we do not want to touch the tables.  The MC spot positions are still consistent with those measured earlier this afternoon, before this work, so I'm not concerned.

We confirmed that both green beams are hitting a good place (centered in pitch, and just left and right of center in yaw) on the mirror in the OMC chamber, and are getting to the center of the first mirror on the PSL table.  We then coarsely aligned the beams on the PSL table.

We then relocked and aligned the arms for IR, and checked that the AS beam is centered on the mirrors in the BS chamber, and that the beam is coming out, and to the AS table.  I touched the last mirror before PZT3 a small amount in yaw, and then PZT3 in pitch and yaw, until we saw the beam recentered on the first mirror on the AS table.  At that point, we were also back to the center of the AS camera (which is good, since Koji had aligned all of that the other day).  So, the AS beam is good.

We checked IPPOS, and have centered the beam on all the mirrors, and aligned the beam onto the QPD. 

We checked IPANG, by looking through the viewports at the mirrors in the ETMY chamber.  We are now centered in yaw, but clipping a bit low.  This is what we want, since we always end up drifting high during the pump-down. 

We see a nice, unclipped REFL beam on the camera.

We see a beam a little high on the POP camera, but Koji looked on the table with a card, and saw the beam....we just need to do minor alignment on the out of vac mirrors.

We checked again that the green TEM00 beams from both arms come to the PSL table. 

We are getting POX and POY out, since we are using them to lock and align the arms.

Manasa and Koji recovered one clean allen key from the bottom of the chambers, but one remains, as a sacrifice to the vacuum gods. 

I believe that, with the exception of checking the oplevs and taking photos of PR3, and the green steering optics, we have finished all of our vent tasks.  We should do a quickie alignment on Monday, check the oplevs, take some photos, and put on the heavy doors.  Pumping can start either Monday afternoon or Tuesday morning. 

 

  8974   Tue Aug 6 19:53:15 2013 JenneUpdateLSCArms locked in IR, aligned. IFO at nominal power

[Koji, Manasa, Jenne]

The Y arm was locked in IR, and we saw flashing in the Xarm (Gautam had the Xarm for green work when we began).  I checked IPANG, and the beam was beautifully unclipped, almost perfectly centered on the first out of vacuum mirror.  I aligned the beam onto the QPD.

We then swapped out the MC Y1 that we use at low power, and replace the usual 10% BS, so that we wouldn't crispy-fry MC REFL.  Manasa adjusted the half wave plate after the laser, to maximize the power going toward the PMC.  We relocked the PMC, and see transmission of ~0.84, which is at the high side of what we usually get.  The beam was aligned onto MC REFL and centered on the WFS, and the MC was locked at nominal power.  Koji tweaked up the alignment of the MC, and ran the WFS offset script.  I aligned beam onto POP QPD and POP110 coarsely (using a flashing PRC, not a locked PRM-ITMY cavity, so the alignment should be rechecked).  The arms have both been locked and aligned in IR....the green beams need to be steered to match the current cavity axis. 

The AS beam, as well as REFL and POP, are all coming out of the vacuum nicely unclipped. 

Notes:  When Koji was aligning the SRM to get the SRC cavity roughly aligned (the AS flashes all overlapping), we noticed that there is some major pitch-yaw coupling.  Serious enough that we should be concerned that perhaps some connector is loose, or an actuator isn't working properly.  This should be checked.

Moral of the story:  Coarse alignment of all mirrors is complete after pump-down and we have IR locked and aligned to both arms at nominal power.

 

Still to do:

* Restore PRM, align beam onto the REFL PDs. 

* Lock PRM-ITMY cavity, align beam onto POP PDs.

* Align AS beam onto AS55. 

* Recenter all oplevs.

* Recenter IPPOS and IPPANG at nominal power.

* Start locking!!

  8980   Wed Aug 7 19:16:20 2013 JenneUpdateASCASS setting up accelerated more

I have furthered Koji's work, and moved the filter on/off state for all the filter banks also to the burt snapshot.  

Turning on the ASS is now much faster than it was originally, with the ezcawrites in series.

  8981   Wed Aug 7 21:52:11 2013 JenneUpdateSUSSRM coils fine - problem with slow bias slider

[Koji, Jenne]

We have looked a little more at the SRM situation.  We aligned the SRM, and then aligned the oplev, so that we had a convenient monitor of the optic's motion.

When we use the _COMM channels, which are the usual ones on the IFO_ALIGN screen, the pitch slider makes pitch motion, but the yaw slider makes the oplev spot move ~45degrees from horizontal.

However, when we use the bias channels that are in the front end model, parallel to the ASC path, pitch moves pitch, and yaw moves pure yaw.

So, we conclude that the SRM coils are fine, and there is something funny going on with the slow part of the actuation. 

Koji restarted the slow computer susaux, and burt restored it, but that did not fix the situation.  We went inside and looked at all of the ribbon cable connections, and pushed them all in, but that also has not fixed things. 

We have been looking at D010001-b, the coil driver board, and we think that's where the summing resistor network between the slow bias slider, and the coil outputs from the fast model exists.  (It's not 100% clear, but we're confident that that's what is going on). 

Tomorrow, we will pull the SRM's coil driver board, and see if any of the components in the slow slider path, before the summing point, look burned / broken / bad.

  8995   Mon Aug 12 12:57:59 2013 JenneUpdateCDSX-End Green ASS - Roundup

Quote:
  1. The SIMULINK model has been modified to accommodate an option to dither the cavity mirrors and not the PZT mirrors. Details are as follows:
    • I have sent the LO signals (CLK,SIN and COS) from the ASS model to the ASX model via the RFM model. Appropriate changes were made to all these three models, and recompiling and restarting the models was done without issue. The SIN and COS signals are used to demodulate green transmission at the dither frequencies. ***The CLK signal is not required to be sent between models as it is not being used by ASX (I turn the dither ON using the channels already set up for ASS). I realised this a little late, and at present the ASS and RFM models are compiled such that the CLK signal is also sent from ASS to RFM. This can be removed, thus freeing up 4 unnecessary inter-process communication channels. Also, I am not too sure if this is relevant, but the maximum computation time of both the RFM and ASX models seem to have gone up after I added these inter-process communication links.***

    •  

 Getting rid of the LO transmission will certainly help / be good.  After adding these channels, the RFM model is regularly hitting 62usec (out of a max acceptable of 60).

I'm not really sure why the ASS was involved in this.  I feel like it might have been simpler to just do everything in the ASX model, to keep things cleaner.  Also, the IPC blocks for this stuff (in both ASS and ASX) are not on the top level of the model.  I had thought that this was expressly forbidden (although I'm not sure why).  I'm emailing Jamie, to see if he remembers what, if anything, is breakable if the IPC blocks are down a level.

  8997   Mon Aug 12 14:05:34 2013 JenneUpdateASCPRCL ASS software in place

Quote:

- We are ready to implement ASS for PRM

 I have added an IPC sender from the LSC model, to send POPDC to ASS.  I have copied over the structure of the arms' ASS, to do the same for PRCL.  I have set it up to dither the PRM, and feed back to the PRM.  I did not include an LSC set, since I'm assuming that we'll set the input pointing with the arms, and just want to move the PRM to maximize POPDC.

Models have been compiled, installed, and restarted, and the daqd was restarted.

  8998   Mon Aug 12 15:39:40 2013 JenneUpdateASCPRCL ASS screens in place

I have added the PRCL ASS to the main ASS screen, and created the servo and lockin screens.  The filters loaded are the same as those used for the arms (bandpasses and lowpasses for the lockins, and an integrator for the servo).

I'm going to try to lock, and get the ASS to work.

  9001   Mon Aug 12 23:13:14 2013 JenneUpdateASCPRCL ASS software in place

Quote:

Why POPDC???

 I guess I was thinking that POPDC was a proxy for any type of PRCL lock.  Even if we're sideband locked, there is still some signal in POPDC (although it is very small relative to a carrier lock - ~40cts vs. 1,000cts).  However, as soon as this question was asked of me, I realized that one of the 2f demodulated signals made more sense. 

Since I want the ability to choose between POP110 and POP22, I have put a little 1x3 input matrix before the PRCL lockins in the ASS model.  Since POPDC was already there, I included it as an option in the matrix (in case we ever want to do some PRCL ASS after we have some carrier resonating as well). 

  9030   Mon Aug 19 11:30:20 2013 JenneUpdateIOOMC mirrors' ASC has non-zero inputs

[Masayuki, Jenne]

When I came in this morning, I noticed that the Mode Cleaner had not been locked for at least the past 8 hours.  We moved the MC SUS sliders until the MC SUSPIT and SUSYAW values for each mirror were back to approximately the place they were the last time the MC was nicely locked (~12 hours ago).  This got the MC flashing TEM00, so we thought we were doing well. 

However, if the servo was enabled, any time the cavity flashed a small-order mode (especially 00), the mirrors would get super kicked.  Not good

We went to investigate, and discovered that the RFPD aux laser was left on again.  We turned that off, however that didn't fix the situation. 

Manasa suggested checking that the WFS were really, really off.  When we looked at the WFS master screen, we noticed that although the WFS servos were off, the MC mirrors' ASC filter banks had non-zero inputs.  We checked, and this is not from the MCASS, nor is it from the MC WFS lockins.  At this point, I have no idea where these signals are coming from.  I have turned off the ASC outputs for all the MC mirrors (which means that we cannot turn on the WFS), and the MC locks fine

So, we need to know where the ASC signals are coming from.  There isn't anything that I can see, from any screen that I can find, that indicates some signals being sent over there.  Has anyone done anything lately?  I know Koji was working on IPC stuff the other day, but the MC was locking fine over the weekend until yesterday afternoon, so I suspect that's not the culprit. 

I have turned off the outputs of the WFS lockins, as part of my turning things off, so if whatever script needs them doesn't enable them, they should be turned back on by hand.

  9036   Mon Aug 19 23:08:31 2013 JenneUpdateLSCDRMI sensing signals

Here are a bunch of sensing signals.  The configuration is always DRMI.  Except for the optic noted in the title and the x-axis of any individual plot, other optics are held in their nominal position.  DRMI condition is sidebands resonant in PRCL, 55MHz sideband resonant in SRCL.  Each plot has an error signal, as well as the 2f signals at POP and AS.

 The phases of POP22 and POP110 have been adjusted so that the I signal is maximized when everything is at the nominal positions (sideband resonant for PRMI).  The phase of AS110 has been adjusted so that the I signal is maximized when the DRMI is in the nominal position (f2 resonant in SRC).  The phases of the 1f1, 1f2, 2f1 and 2f2 REFL signals were all adjusted to have max PRCL signal in the I phase.  AS55 was adjusted to have max SRCL signal in the Q phase.

 DRMI_PRM_REFL11I.png

DRMI_PRM_REFL33I.png

DRMI_PRM_REFL55I.png

DRMI_PRM_REFL165I.png

DRMI_MICH_REFL11Q.png

DRMI_MICH_REFL33Q.png

DRMI_MICH_REFL55Q.png

DRMI_MICH_REFL165Q.png

DRMI_SRM_REFL55Q.png

DRMI_SRM_REFL165Q.png

DRMI_SRM_AS55Q.png

 

  9038   Tue Aug 20 01:28:47 2013 JenneUpdateLSCREFL investigations

According to the wiki, REFL 11 has a transimpedance of 4.08kV/A, and REFL 55 has a transimpedance of 615V/A.  This is a ratio of ~6.5 .  My optickle simulations from earlier this evening indicate that, at maximum, there is a ~factor of 2 more signal in REFL 11 than REFL 55.  This is a factor of order 10-15.  Then, REFL 55 has 15dB whitening gain, which is a factor of ~4.  So, this explains why we're seeing so much more digital signal on REFL11 than REFL55.

Tomorrow, I need to replace the 50/50 beam splitter that splits the beam between REFL55 and REFL11 (33 and 165 have already had their light picked off at this point).  I want to put in a 10% reflector, 90% transmission beamsplitter.  Steve, can you please find me one of these, and if we don't have one, order one? This will give us a little more light on 55, and less light on 11, so hopefully we won't be saturating things anymore.

 

  9041   Tue Aug 20 11:52:20 2013 JenneUpdateLSCREFL investigations

Quote:

As I always tell everyone: Don't use a 10% reflector which produce ghost beams. Use a 90% reflector. 

 Hmmm, yes, I forgot (bad me).  I'll find a 90% refl BS, and swap the positions of REFL11 and REFL55.

  9043   Tue Aug 20 18:42:57 2013 JenneUpdateLSCREFL investigations

I have done the swap in the REFL path.  First, I swapped the positions of REFL11 and REFL55.  Then, I swapped out the 50/50 BS for a 90% reflection BS.  (90% goes to REFL55, 10% goes to REFL11).  I also changed the aluminum dump that was dumping the old REFL165 path into a razor dump.

Before: REFL11 had 4.0mW, REFL55 had 3.1mW.  Now, REFL11 has 0.53mW, and REFL55 has 6.9mW.  REFL165 still has around 61mW of light, and REFL33 has 3.3mW (the things that were changed were after 165 and 33 in the REFL path). 

Now, the DC value of the REFL PDs are:  REFL165 = 10.4V, REFL33 = 110mV, REFL55 = 232mV, REFL11 = 18.6mV. 

As I was finishing aligning the beams onto all of the REFL diodes, Manasa asked for the IFO so she and Masayuki could continue their work on the Xarm, so I'll check the signals acquired a little later.

  9049   Thu Aug 22 02:40:12 2013 JenneUpdateLSCDRMI Locked for 1+ minute!!!!!!

[Jenne, Koji]

The DRMI has been locked!!  And at least one time, it was for more than one minute!! 

DRMI_First_Lock_1plusMinute_21Aug2013.png

We are not 100% sure yet that it's correctly sideband locked.  The test of this was to put a 50% BS in front of the AS camera (so after the beam has gone to AS55), and send the light over to a PDA10CF Thorlabs PD.  I locked the Michelson on carrier for the alignment of this diode.  Then I strung a cable to the control room, and plugged it into the RF spectrum analyzer.  (First, I had turned off the green beat PD power, so there wasn't any RF stuff on the line that I unplugged).  It's hard to watch the screen and a tv / dataviewer at the same time, so I've taken a video, so that we can see the nicely locked round DRMI beam on the AS camera, and the spectrum analyzer.  My phone is working very hard at uploading the video, but we may have to wait until tomorrow for that.  However, I think that we're locked on the 55MHz sideband. (Also, maybe I'm too tired or excited or something, but how do you make the real cameras take video??)

EDIT:  Video uploaded.  Pause the video at 10 seconds, and you'll see that we've got a strong 110MHz peak!!  Hoooray!  The TV in the upper right side of the video is AS.  You can see as we flash, the peaks go up and down.  When there's no resonance, the 110 peak goes away. (Ex., when I'm PRMI locked on the sideband, there isn't a visible peak).

 

Alignment procedure was as normal:  Lock and align the arms. Misalign ETMs. Check that MICH fringes look good (ASS does a nice enough job that I don't actually lock and align the Michelson anymore).  Restore the PRM.  Lock PRMI.  Tweak PRM alignment to maximize POP110I.  At this point, Koji and I played a little with the PRMI, but when we finished with that, we restored the SRM, and tweaked its alignment by making nice overlap on the AS camera.

Then, we tried some DRMI settings, started seeing some locks, and played a bit with trying to optmize the settings that we have. 

DETAILS:

PRMI settings: 

PRCL ASC is on (with loop triggering).  MICH gain = -0.8, PRCL gain = +0.05.  FM4, FM5 always on, FM2 triggered.  Loop and filter module triggering on POP22I.  No power normalization.  MICH and PRCL locked on REFL55 I&Q, with 1's in the LSC input matrix.  PRCL actuating on PRM with +1, MICH actuating on BS with +0.5, PRM with -0.267. 

I took transfer functions between REFL55 I&Q and REFL11 I&Q, to determine the relative gains and signs.  REFL11I's gain should be -18dB relative to REFL55I, with the opposite sign.  We tried PRMI locking with MICH = 1*REFL55Q and PRCL = -0.125*REFL11I for the input matrix.  Still no power normalization (we haven't used power norm at all today, so I'll quit writing that).

I took transfer functions between REFL55 I&Q and REFL33 I&Q.  REFL33I's gain is -8dB relative to REFL55I, but they have the same sign.  We tried locking PRMI with MICH = 1*REFL55Q and PRCL = +0.6*REFL33I.  Success.

Next up, some Optickle simulations, to help us go in the right direction for DRMI locking.  I checked the signs of the error signals REFL55I (PRM sweep), REFL11I (PRM sweep) and REFL55Q (MICH sweep) in both PRMI and DRMI configurations.  For all of these cases, the signs were the same (i.e. no sign flips needed to happen for DRMI locking, relative to PRMI locking).  I checked the sensing matrices for DRMI and PRMI for those same signals, and took the ratios of the sensing matrix elements.  This gave me the ratio of optical gains for each error signal, in the DRMI case vs. PRMI case, so any servo gain changes should be the inverse of these numbers.  These numbers are all DRMI/PRMI:  REFL55I PRCL response = 0.76, REFL11I PRCL response = 0.99, REFL55Q MICH response = 18.  So, when trying to lock the DRMI, we wanted to keep the gains for PRCL about the same, reduce the servo gain for MICH by a factor of ~20, but keep the same signs for everything.

In doing that, we started seeing some short DRMI locks, so we twiddled some parameters (mostly the elements in the LSC input matrix) a bit.  We eventually settled on:  PRCL = -0.125*REFL11I, MICH = 0.1*REFL55Q, and SRCL = 1.0 * REFL55I.  The output matrix was the same (MICH pushing on BS and PRM, PRCL on PRM), with the addition of a +1 in the SRCL -> SRM element.  For all 3 degrees of freedom (PRCL, MICH, SRCL), FMs 4 and 5 were always on.  For PRCL, FMs 2,3,6 were triggered to come on after 0.5 seconds of delay.  The PRCL FM triggers helped enormously.  I tried several other things, including changing the MICH input matrix element up and down in value, changing the SRCL input matrix element up and down in value, and engaging triggering for a few different filters in the MICH and SRCL degrees of freedom.  However, none of these made things better, and several made things worse.  Most notably, for SRCL, engaging triggering for FMs 2 and 3 kicked the cavities out of lock, which implies that perhaps our gain isn't high enough yet (and thus our UGF isn't very high yet).  I changed FM1 of SRCL to be +3dB of gain (from +10dB), and it would live through that coming on (trigger delayed by 1 sec, then ramping up over 1 second), but within a second after the filter finishing coming on, the cavity would fall out of lock (not violently kicked, just not locked anymore). 

At this point, we were trying to figure out a way to confirm what kind of lock we had.  I checked Optickle again, and we do not expect to see a significant change in POP110I between the PRMI and DRMI cases, so that isn't a useful check.  We dreamed of having our AS110 demod board, or the AS OSA set up, but neither of those was going to happen tonight.  Instead, Koji suggested hooking up the PD, and looking directly at the output. 

To-do:  Set up the AS OSA.  Also, perhaps temporarily borrow the 110 demod board from POP.  We were triggering on POP22 tonight, and that seemed to work okay.

 

 

  9052   Thu Aug 22 13:03:40 2013 JenneUpdateLSCDRMI Locked for 1+ minute!!!!!!

Quote:

  Very nice!!  I was wondering, shouldn't the driving matrix be such that MICH pushes on SRM as well?

 Hmmm, yes, that's a very good point.  I think you're right, and I'll give that a try today.

  9057   Fri Aug 23 01:52:34 2013 JenneUpdateSUSViolin filters moved to LSC, from SUS

[Rana, Jenne]

We were meditating a little bit on what may be the story behind the PRM violin filter situation.  We locked the PRMI, and turned on and off the violin filters.  We noticed, very bizarrely, that when the violin filters were ON, the servos would oscillate.  Weird.  Also, probably because the oscillation was causing us to hit the limit we have in the MICH servo, we rung up a 3rd harmonic of one of the violin modes, which was at 1955 Hz. 

We took a transfer function of the PRCL servo, saw that the UGF was 300 Hz, and lowered it to ~180 Hz.  After later investigations, that high-ish UGF probably wasn't a problem.  Anyhow, we then took MICH servo transfer functions, and saw some very weird stuff. 

At frequencies where we had violin filter notches, we were seeing peaks in the transfer function, which came close to touching, or crossed the 0dB line!  We suspect that this may have something to do with the balancing of the drives to the optics, since we have PRCL driving PRM, but MICH driving BS and PRM.  What we did was move the violin filter notches into the LSC model.  There were already SUS filter banks in the LSC model (right side of the LSC screen).  In preparation for the DRMI, I have put the BS violin notches into the BS, PRM and SRM filter banks, as well as the PRM and SRM filters into all 3 banks.  Right now for PRMI, I have the BS and PRM notches (as well as the Vio3 notch) turned on in both BS and PRM.  All of the violin-related filters are turned off in the LSC filter bank inside the SUS models.  When we did this, the servo oscillations no longer are excited when we turn on the notches, and when we take a new transfer function, there are no longer weird peaks at the notch frequencies.  More meditation needs to be done.

Also, for the violin3 filter, Rana noted that at 1955 Hz, after we confirmed that the REFL 55 phase was set correctly (and we're using REFL 55 I&Q for PRMI locking), the I-phase had a response of 0.36, while the Q-phase had a response of 0.20.  I should be able to think about these numbers, and decide if the vio3 is for the BS or the PRM violin mode.

 MICHloopNotches_23Aug2013.pdf

the above series of Bode plots shows the MICH Open Loop Gain as the REFL55 phase is adjusted (PURPLE, ORANGE) with the notches in the SUS and then (RED) as the notches are moved to the LSC and made the same for all optics.

In other news, I have the parts that Jamie ordered to make a new 110 demod board, so that's one of my daytime activities now, so we can have both POP110 and AS110.

  9062   Mon Aug 26 18:55:18 2013 JenneConfigurationElectronicsputting together a 110 MHz LSC demod board for AS

I have modified one of the spare demod boards that was sitting above the electronics bench (the one which was unlabeled - the others say 33MHz, 55MHz and 165MHz) to be the new AS110 demod board.  In place of the T1 coil, and the C3 and C6 resistors, I have put the commercial splitter PSCQ-2-120+.  In place of U5 (the low pass for the PD input) I have put an SCLF-135+. 

In order to figure out how to make the pinout of the PSCQ match up with the available pads from T1, I first pulled the "AS11" board (it's not something that we use, so it would be less of a tragedy if something happened while I had the board pulled).  However, while the PCB layout is the same, the splitter for the low frequencies (PSCQ-2-51W) has a different pinout than the one I need for the 110MHz.  So, I put AS11 back, and pulled the POP110 board. (After I noted the pinout on POP110, I reinstalled that board.  To get it out, I had to unplug the I and Q outs of POP22, but I have also replugged those in).

For my new AS110 demod board, I copied the pin connections on POP110.  I have made a little diagram, so you can see what pins went where.  The top 2 rectangles are the "before" installation cartoon, and the bottom is the "as installed" cartoon.

AS110_demod_board_modifications.pdf

The one thing that must be noted is that, because of the pinout of the splitter and the constraints of the board layout, the +0 degrees (I-phase) output of the splitter is connected to the Q channel for the rest of the demod board.  This means that the +90 degrees (Q-phase) output of the splitter is connected to the I channel for the rest of the demod board.  This is not noted for POP110, but is true for both:  The I and Q channels of the 110 MHz demod boards are switched.  In practice, we can handle this with our digital phase rotation.

Daytime tomorrow, I will test my new board as Suresh did in elog 4736.  Before we get to use AS110, we need (a) some LO juice from the RF distribution box, and (b) a spot to plug the board in, in the LSC rack.  Meditating on how those are going to happen are also tasks for daytime tomorrow.

  9068   Tue Aug 27 02:18:28 2013 JenneUpdateLSCPRMI, DRMI sensing matrices

I have made a measurement of the PRMI and the DRMI sensing matrices. 

Keiko pointed out to me in an email a little while ago that I wasn't zeroing elements in the oscillator drive matrix after using them, so I was effectively driving all the degrees of freedom at once, which is why some of the recent sensing matrices looked a little bullshitty.  Anyhow, I put in a few lines to zero that row of the LSC  output matrix, so that we don't do that any more. 

PRMI sensing matrix:

SensMatMeas_26Aug2013_withErrorBars.png

DRMI sensing matrix, first-ever measurement, after the optic flipping / recent locking success:

SensMatMeas_26Aug2013_DRMI_firstEverMeasurement.png

Note that we don't have any error bars in the DRMI case, since the IFO fell out of lock during the error bar measurements.  So, we got the "real" data from the degrees of freedom, but not extra data for making error bars.  Also, the MICH / SRCL coupling hasn't been balanced out in the output matrix yet, but since the notches are engaged in the degrees of freedom during this measurement, that shouldn't be a significant effect.

To get the DRMI sensing matrix measured, I added the SRM's actuator calibration to SensMatDefinitions.py (data from elog 5637).  I also created a new file runDRMI_sens, to be the equivalent of runPRMI_sens.  In the new runDRMI_sens, I reduced the actuation from the oscillator by a factor of 10.  I had several attempts at higher oscillator amplitudes that kept kicking the IFO out of lock.

The DRMI was pretty good, but I wasn't getting ~10s of minutes like Koji was on Friday.  I also wasn't able to engage all of the FM triggers that he was.  The 10-30 Hz seismic BLRMS is a little higher than a usual night, but other than that, seismic looks pretty quiet.

My settings for the night:

LSC input matrix:  +0.1*REFL55Q = MICH, -0.125*REFL11I = PRCL, +1.00*REFL55I = SRCL.

Filter settings:  MICH, PRCL, SRCL all had FM4,5 always on.  MICH had FM2,3 triggered.  PRCL had FM2,3,6 triggered.  SRCL had FM2 triggered.  In particular, engaging FM 6 for MICH or SRCL made some loud low-ish frequency oscillation.  Engaging anything other than FM2 for SRCL kicked the IFO out of lock. 

Gains:  MICH = -0.800, PRCL = +0.050, SRCL = -0.100

Triggering:  All triggered on POP22I, upper = 50, lower = 10 (lower = 25 for SRCL).

FM trigger thresholds: MICH on = 35, off = 2, delay = 2 sec.  PRCL on = 35, off = 2, delay = 0.5 seconds.  SRCL on = 80, off = 25, delay = 5 sec.

Power normalization:  None, for any degree of freedom.

LSC Output matrix:  MICH = -0.267 for PRM, +0.50 for BS.  PRCL = +1.0 for PRM.  SRCL = +1.0 for SRM. 

LSC SUS filters:  BS, PRM, SRM all had FM1,2,3,6 engaged for the BS, PRM and SRM violin filters, as well as the 3rd order harmonic for one of them.

Other notes: 

I tried locking the SRMI, so that I could do the same kind of actuator calibration that Koji did for the PRMI in elog 8816, but was unsuccessful.  I checked optickle, and found that for REFL 55 I&Q locking, MICH and SRCL keep the same signs for SRMI as DRMI.  Also, for both, the optical response is a factor of ~15 lower for SRMI than DRMI, so the gains should be higher by a factor of 15 for both MICH and SRCL.  I think my big problem here is that I don't have anything to trigger on.  There isn't any signal to speak of in the POP PDs, with the PRM misaligned.  Hopefully we'll have AS110 shortly, and that will help.

I updated the IFO Configure restore scripts to our latest versions of locking.  I have also tested them, and restoring the Michelson, PRMI and DRMI all seem to work. (MICH restores to locking with AS55Q.  PRMI restores to locking with REFL165 I&Q.  DRMI restores to the settings noted above in this entry.)  The X and Y arm restores have been working, and I have been using them (semi-)regularly since I announced them in elog 8433 back in April.  Still to-do though:  Add PRCL ASC to the PRMI up script, and make the dither options work for at least the arms and PRM.  (Just need to point the drop down menu options to the new ASS scripts.)

 

 

  9069   Tue Aug 27 15:31:48 2013 JenneConfigurationElectronicsputting together a 110 MHz LSC demod board for AS

Quote:

Quote:

I have modified one of the spare demod boards that was sitting above the electronics bench (the one which was unlabeled - the others say 33MHz, 55MHz and 165MHz) to be the new AS110 demod board.  In place of the T1 coil, and the C3 and C6 resistors, I have put the commercial splitter PSCQ-2-120+.  In place of U5 (the low pass for the PD input) I have put an SCLF-135+.

OK, but what kind of filter should we be actually using? i.e. what purpose the 135 MHz low pass serve in contrast to a PHP-100+ ?

 Hmmm. Indeed. This is just cutting off higher frequency stuff, but anything from other lower sidebands still gets through.  I should actually stick in the SXBP-100's, which will band pass from 87-117 MHz.  These have an insertion loss at 100 MHz of 1.64 dB. 

Jamie ordered 2 of these, so I can put one in each of AS110 and POP110. 

  9071   Tue Aug 27 17:32:52 2013 JenneConfigurationElectronicsputting together a 110 MHz LSC demod board for AS

I measured the phase split between the I and Q signals of my AS110 board.  To do so, I plugged the board into an empty slot next to the PD DC readout / whitening board in the LSC rack.  I borrowed the POP110 local oscillator, and used a Marconi to generate a "PD input".  (I'm roughly following what Suresh did in elog 4736).  Our 11MHz is currently 11.066134MHz, so I had the Marconi going at 110.662340 MHz (1kHz from 10*11MHz), and I had the Marconi source at -13dBm.  

I took a transfer function using the SR785 between the I and Q outs of the AS110 demod board, and got a magnitude misbalance of 0.809 dB, and a phase split of 110.5 degrees.  This isn't so close to 90 degrees, but this may be a problem with the splitter that we're using, as Suresh detailed in elog 4755.  In that elog, he measured a phase split of POP110 of 105 degrees, unless the power going into the splitter was pretty high.  As with POP110, since I expect that we'll usually only look at one channel (I, for instance), this isn't such a big deal for AS110. 

I have left, for now, the board in the empty slot.  It looks like (I'm going to go check) there are 3 open channels on the whitening board that has the PD DC signals.  So, the only thing left to figure out is how we want to get some local oscillator action for this new board.

EDIT: Yes, those channels are available.  Right now (as a remnant from testing the whitening filters waaaay back in the day) they are called C1:LSC-PDXXX I, Q, DC.  I'll use 2 of those for the AS110 I and Q. 

  9072   Tue Aug 27 18:21:35 2013 JenneConfigurationElectronics110 MHz LO options

As I see it, we have a few options for getting the 110 MHz LO to both the POP110 and AS110 demod boards.  

The current situation is described by Kiwamu in elog 5746.  The 55 MHz signal comes into the box, and is split 4 ways, with each path having 19.7 dBm.  One of these 4 is for 110.  It has a 2dB attenuator (giving us ~17.7 dBm), and then it goes to an MK-2 frequency multiplier.  I'm a little lost on why we're giving the MK-2 17 dBm, since it says that it can handle an input power between 1 - 15 dBm.  It has ~16 dB conversion loss, so the 110 output of the distribution board has (according to the drawing) 1.9 dBm.  The demod boards have a 10 dB attenuator as the first element on the LO path, so we're giving the ERA-5 -8 dBm. 

We can either amplify the 110 leaving the distribution box, split it, and then attenuate it to the appropriate level for the demod boards, or we can change the attenuators on the POP110 and AS110 demod boards. 

Since we seem to be over driving the 2x frequency multiplier, I think I should change the 2dB attenuator to a 5dB attenuator, so we're giving the 2x multiplier ~15 dBm.  The conversion loss of ~16 dB means we'll have -1 dBm of 110 MHz.  I want to amplify that by ~10 dB, to give 9 dBm.  Attenuate by 5 dB to get to 4 dBm, then split into 2, giving me 2 110 MHz spigots, each of ~1 dBm.  Since the demod boards expect between 0-2 dBm for the LO's, this should be just fine.

Thoughts, before I start scrounging parts, and pulling the RF distribution box?

  9077   Wed Aug 28 00:41:23 2013 JenneUpdateCDSCDS svn commits not happening

svn status update. asx, als and ioo were found not committed. Not sure about who modified ioo last after Jenne.

//edit Manasa - edited the/ elog instead of replying //

  9078   Wed Aug 28 03:28:00 2013 JenneUpdateLSCPlaying with DRMI, some ASS automation prep

[Rana, Jenne]

We did lots of poking around with the DRMI tonight.  I should elog more in the morning, but the most important points are:

Locking settings same as elog 9068, except PRCL gain changed to 0.035, and the FMs that are triggered.  PRCL tonight had FM2,3,6 triggered.  MICH had FM1,2,3,7 triggered.  SRCL had FM1,2 triggered.  Engaging the MICH boosts helped make things more quiet, so that some of the SRC boosts could be enabled.  Still not as good of lock stretches as Koji got last Friday (elog 9060). 

REFL55 and REFL11 were still saturating (only during acquisition), after the optical path changes I did last week (elog 9043).  We reduced the REFL55 whitening slider from 15 dB to 6 dB (but forgot to compensate with digital gain), to keep the counts (as seen on DTT time series, binning off) to less than ~20,000 counts.  REFL11 is still saturating, and we're not sure why, since it's slider gain is 0 dB.  To be investigated.

I was prepping the ASS to be more conveniently put into a wrapper script, which could be called from the IFO Configure screen.  This involved adding PRCL to the burt .req and .snap files, as well as modifying the scripts a little bit to include PRCL as an option.  I ended up changing the script names from DITHER_Arm_ON.py and DITHER_Arm_OFF.py to DITHER_ASS_ON.py adn DITHER_ASS_OFF.py, since they are no longer restricted to being arms-only.  You must still provide an argument to the script, to tell it which degree of freedom you want to activate.  I also changed the save offsets scripts.  The way they were, the X and Y arms just had separate hard-coded scripts, with no convenient way to incorporate PRCL.  I merged them (including PRCL) into WRITE_ASS_OFFSETS.py, which you must now provide the DoF as an argument.  I tested these new scripts on all 3 of the DoFs, and made changes to the ASS screen, so it now calls only the new scripts.  It should now be easy to incorporate future ASS modifications.

Rana was in the middle of modifying the ASS model to include SRCL, and we also need to include MICH.  The ASS model is not compile-ready, so don't compile it!!  If you need to compile the ASS, please save what's there as a different name, and do an "svn up" to get the latest working version.


We suspected that there might be angular drive issues with the SRM (it was wiggling a lot). We checked the damping via step responses - all Qs were less than 10. Then we found that the INPUT button on the SRM PIT OL was OFF (why ???). After turning this back on it behaved better. We measured the loop shape and found that the UGF was 7 Hz; good. Need to work on some loop shaping for this guy. Its just 1/f out to 300 Hz right now. UGF should be made a little lower so that we can stably turn on the Bounce/Roll notches and a ~50 Hz low pass filter.

Most importantly, the F2A filters need to be measured and implemented. They are a few years old.

  9094   Mon Sep 2 15:22:57 2013 JenneUpdatePSLPMC relocked

 The PMC was locked on an LG 10 mode (or something like it), for at least the last 8 hours.  I relocked it on the regular 00 mode, and it's fine now.  

Also, in CDS news, I did an mxstream restart (the RCG upgrade is supposed to make this not an issue anymore...), and did a "diag reset" afterwards, and all of the IPC errors except for one in the LSC model have gone away (OAF is still not running....on my to-do list, but not super high priority).

  9095   Mon Sep 2 16:46:32 2013 JenneUpdateElectronicsRF distribution box is on the bench

I have pulled the RF distribution box out of the rack, so I can look at it, and modify it to have 2 110 MHz spigots. I'm going to make the mods as in elog 9072.

Before I pulled the distribution box, I turned off the RF Generation Box, so don't be surprised that the MC will not lock.  I have terminated the cables that bring the 11 and 55 MHz signals from the generation box to the distribution box, so if someone does turn on the generation box, there won't be bad reflections.

To get the box out, in addition to unplugging all of the cables that go to the distribution box, I had to disconnect 2 of the ADC ribbon cables from the top row of RFPD demod / whitening / ADC boards, since they were in the way.  Everything is labeled, so it should be easy to put back together.

Note to Future Jenne:  Past Jenne put the screws needed for those ADC cables and to hold the box in the rack, in the plastic box that is on the floor in front of the LSC rack. 

Also, I measured the 110 MHz port before I pulled the board, so I would know what my "before" looked like.  I was using the 300MHz 'scope's measurement functions, so these are in volts, not dBm.  Amplitude = 1.33V, RMS = 456 mV, freq = 109.4-111.9 MHz

  9096   Mon Sep 2 18:06:21 2013 JenneUpdateElectronicsRF distribution box: 110 MHz LO options

After scrounging for parts, and opening up the box, I have modified my proposal to the following:

RF_distribution_box_proposed_modifications.pdf

Note that the freq multiplier is supposed to take, at maximum, 15 dBm.  The reason I put the 5 dB attenuator, then an amplifier, then another attenuator is that I don't know of / can't find easily a 10 dB amplifier with the usual case type on the MiniCircuits site.  (If anyone knows of one off the top of their head, that would be handy.  Then I'd remove the attenuator between the multiplier and the amplifier, and make the 10 dB attenuator a 5 dB.)

Anyhow, the ZFL-500HLN can only output 16 dBm of power, and I don't think I have space for another ZHL-2 (which can output up to 26 dBm) inside the box, so I put an attenuator before, as well as after, the amplifier. 

I think I have space inside the box for all the bits and pieces I'll need, although to do things correctly, I need to drill holes in the teflon mounting plate to mount the amplifier and splitter.

0902131751.jpg

I also think that I have space on the front panel to put another isolated SMA feedthrough.

0902131751a.jpg

I have, on my desk, all the parts (except for mounting screws, and cables between things) to make these modifications to the distribution box. 

  9099   Tue Sep 3 21:08:13 2013 JenneUpdateElectronicsRF distribution box: 110 MHz LO options

The RF distribution box is still on the bench, so again, don't be surprised that the MC doesn't lock.

I have completed my modifications as proposed in elog 9096, but I want to do a couple of quickie tests in the morning before I declare it ready for service.

  9100   Tue Sep 3 21:10:36 2013 JenneConfigurationElectronicsputting together a 110 MHz LSC demod board for AS

Quote:

 

 I should actually stick in the SXBP-100's, which will band pass from 87-117 MHz.

 I have removed the 135 MHz low pass from my new AS110 demod board, but these SXBPs have different feet than the SCLFs, so I want to confirm with Koji or someone that I can solder them in the same way, before I get carried away and destroy anything.  I should be able to finish this up tomorrow, plug in the demod board and the distribution box, and try out AS110 triggering, etc, tomorrow night.

  9101   Wed Sep 4 16:06:40 2013 JenneUpdateElectronicsRF distribution box: Reinstalled

I have reinstalled the RF distribution box, as well put in the AS110 demod board.  I plugged everything back in, and turned it all on.

The switch on the distribution box may be starting to fail.  When I was turning the box on, I could depress the button, and see the blue glow, but it wouldn't catch, so when I removed my finger, the glow went away.  I was afraid that I'd have to pull the box, but after a few more button toggles, I got it to stay on.  I'm leaving it for now, but we should remember that this may be a problem.

I will look at the phases of all the PDs, but none should need changing except POP 110.  Every other PD has the exact same cables as before.

  9103   Wed Sep 4 17:22:09 2013 JenneUpdateLSCDemod phases for RFPDs

I checked the demod phases for AS55, POP110, and all the REFL PDs. 

AS55:  I locked MICH, and shook the ITMs (+1 for Y, -1 for X), and watched the AS55 I & Q spectra at 580Hz (notch in the servo was enabled).  I rotated the phase from -32.0 to +13.0 to get the signal entirely in the Q phase.

POP110:  I locked the PRMI (triggering on POP22), and maximized POP22.  I then rotated the phase of POP110 until the signal was maximally positive.  I forgot what the starting phase was, but it is now 84.  The POP11_I signal was entirely negative when I started, so the new phase is about 180 from the old phase.  I also checked by unlocking the cavity, and seeing that a large peak in POPDC corresponded to large negative dips in POP110_I and POP22_I.

REFL PDs:  I locked the PRMI, and shook the PRM (notches in the servos were enabled for both MICH and PRCL).  Maximized the peak in the I phase.  REFL11 was fine, REFL33 was fine.  REFL55 was changed from 120 to 45.  REFL165 was changed from 106 to 96.

I restored the SRM on the IFO_ALIGN screen, but the saved value was almost 2 full integers off in yaw from actual DRMI resonances.  It looks like it was saved when Rana and I were working late last week.  We must have accidentally saved it when it was misaligned, since hysteresis can't do that much.

I want to check the phases for POX and POY with arm locking, just in case.  Also need to set the AS110 phase (which is plugged into the AS11 channels - need to fix the channel names).

 

  9107   Wed Sep 4 22:14:35 2013 JenneUpdateSUSMC2 tickler turned OFF

Quote:

 

 Sounds like this was just incidental, since the MC locked fine also with the tickler enabled for weeks.

The tickle is disabled by the down script, but there's no way to correctly handle all possible button pushes. If you want to disable the autolocker for some reason you should run mcdown before trying to lock. This will set up things with the correct settings.

 Isn't that backwards?  Shouldn't the tickler be enabled by the down script, and disabled by the up script?  Either way, the problem was that, after I acquired lock, the tickler was causing the transmitted power to fluctuate by ~20%, and often the MC would lose lock after a minute or so.  Also, the WFS definitely couldn't be enabled by hand. 

Anyhow, I'll try to keep in mind that this exists, so I'm not stymied by it again.

  9109   Thu Sep 5 01:55:29 2013 JenneUpdateLSCLSC model upated to have AS110 channels, violin filter triggering

I have modified the c1lsc model so that I have access to the AS110 channels in the triggering and power normalization matrices. 

I also put in a few blocks so that we can have triggering on the violin notches that we moved to the LSC model a week or so ago. 

Here is my svn comment, so I don't have to retype things:

2 changes:  AS110 channels added, and Violin filter triggers added.

AS110:     We recently installed a    new demod board    and PD for an AS110 signal.  Since we will not    be using AS11 in the forseeable    future,    the AS110 demod    board outputs use the former AS11 channels.  I    have left the AS11 channels in the model so that we can easily    add them back if we want to, but they are grounded rather than    connected to the ADC.  I've added digital demodulation for AS110, power normalization,    and then added the I&Q signals to both the trigger matrix and the main    power normalization matrix.  NOTE that these slide the matrix columns around.    Since the AS110    is also    using the former AS11 whitening    channels, swapped those on the    BIO block also.

Violins:  Recently, Rana and I moved the SUS LSC violin    filters    from the individual suspension    models over to the LSC model.  Giving every optic every    optics' violin    notch helps eliminate bad cross-coupling between servo loops.  Here, I have enabled triggering    for these notches, so that the violin filters can come on after a cavity is locked.  Since the    filter banks SHOULD BE THE SAME    for all LSC_SUS banks,    the "mask" is common to    all optics.

I also edited several medm screens, to show the new changes:  the lsc overview screen has a button to the violin notch triggering screen, in addition to being able to get to the new screen from the regular triggering matrix screen.  I made the trigger and normalization matrix screens bigger, since there are now 2 new columns. 

I added AS110 to both the LSCoffsets script, and Masayuki's new, better, LSCoffsets2.py. 

I added new lines to the .req files for the ifo configure burt restores for the new matrix columns, and the violin triggering.

I restored, checked out, and saved the Xarm, Yarm, MICH, PRM_sb, and DRM configurations. 

 


I tried locking the DRMI, but haven't really been successful.  I'm not 100% sure how to do the phasing for AS110, so that could be a problem.  For POP, I can watch POPDC to see if something is a carrier or a sideband flash, but I don't have something quite as convenient at the AS port.  I have set the AS110 phase to 60 degrees for now, since during free swinging DRMI flashes, it looks like most of the buildup is in the I phase with 60 degrees.  Even with the same configurations as a week or so ago, I'm not getting much more than ~1 second locks.

I also tried locking the SRMI, but am not getting anything at all.  I think I need to go back to simulation-land to figure out what good signals might be.

 


Other thoughts:

Stefan modified the LSC filter module triggering blocks, so now we have a new epics variable, "_INVERT", which sends the trigger through a NOT or not.  I think that we want to keep this variable set to 0 to be the same as things were, but I do need to expose this new variable on the screens.

The trigger and normalization matrices pictured on the LSC overview screen need to be expanded by the 2 new columns.  The actual matrix screens are good, but I forgot to fix up the little Kissel buttons.

When I have a free swinging SRMI, MICH and SRCL should have the same sign for the gain, if I'm using AS55 I&Q for locking.

LLO is using REFL 9I for SRCL, and ASDC for MICH for the SRMI, but I don't have any REFL beam with a misaligned PRM, so I don't think I can copy what Den and Lisa did on Monday night.

I have figured out / rediscovered why the "sqrt" buttons on the power normalization screen aren't restored when you restart the LSC model - They are controlled by momentary epics records, which go to embedded c-code to do some toggling.  I don't know yet of a good way to save the configuration of these guys for burt restore-type restoration.  This will be a problem for anything that is using these toggle c-codes.

  9112   Thu Sep 5 11:19:33 2013 JenneUpdateSUSPRM side

Quote:

I think the crane repair guy accidentally  stepped on the  BS support beam.

PRM side is not coming down.

 Seems fine now.

  9113   Thu Sep 5 15:18:41 2013 JenneUpdateLSCFree swinging DRMI power buildups

I have the DRMI free swinging right now, since it's not really locking.  Looking at these time series in the attached pdf, particularly around time=1.15, it would be super handy to trigger the SRCL degree of freedom on AS110 after the PRMI is triggered on POP22.

  9114   Thu Sep 5 21:07:09 2013 JenneUpdateLSCStarted work on logic for triggering

I want something like an "AND" for the degree of freedom triggers.  Koji and I talked through an idea, and I have it running in the c1tst model, but the logic isn't working like I expect, so I need to look into it more before I can put it into the lsc model.

  9122   Wed Sep 11 17:35:38 2013 JenneUpdateLSCALS requirement

I have done a quickie look at Optickle to see how the linewidth of an arm cavity changes versus the configuration. 

To do this, I make different configurations, and do a sweep of ETMX.  For each configuration, I find the max peak value, and then find the points that are at half that value.  The distance between them is the full width at half max.

I get:

FWHM_DRFPMI = 3.8750e-11  meters

FWHM_PRFPMI = 3.8000e-11  meters

FWHM_SRFPMI = 2.3200e-09  meters

FWHM_FPMI =   1.1900e-09  meters

So, for the ALS to hold within 1/10th of a linewidth for the full IFO configuration, we want the ALS noise to be on the order of 3 picometers RMS.  If I recall correctly, that's about an order of magnitude better than we currently have.

 

ArmLinewidthComparison.png

                 use LOG y-scale

EDIT 8 Nov 2013, JCD:  New log-y plot:

LinewidthComparison.png

  9126   Thu Sep 12 01:06:09 2013 JenneUpdateASCSRCL ASS implemented

I have modified the ASS model to also have an ASS for SRCL.  The input options are POPDC, POP110, AS110.  I suppose I could/should have included ASDC.

Screens are modified / made.  I haven't finished setting the servo gains and oscillator amplitudes, and all that jazz yet. 

Using the parameters that Koji had in elog 9116, I was able to get nice long DRMI locks (several on a ~10 minute time scale). 

I tried some pseudo-ANDing for the triggers, to no avail.  I was trying to have the trigger matrix row for the SRCL loop have 1*POP22 and 0.02*AS110, where the 0.02 is to scale AS110 so that it has a similar amplitude to POP22.  I then set threshold levels to ~250 for up, and 100 for down (I tried several different values for the up threshold).  I was watching the TRIG_MON_FAST channels for both PRCL and SRCL, and I wasn't able to get SRCL to be triggered only at the same times as PRCL using this technique.  Since we can get the DRMI to lock, perhaps my AND logic for the triggers is a low priority, but I think we'll need something like that if we want real logic.

 

  9193   Thu Oct 3 02:51:26 2013 JenneUpdateLSCPRMI locked "forever", some ALS fiddling

First up for me this evening was getting the PRMI locked.

I used the IFO configure screen to lock the X and Y arms, then aligned them using the ASS scripts.  Then used the IFO config screen to restore the Michelson, and did some fine tune tweaking of the BS alignment by looking at the AS camera.  Then, I restored the PRMI from the IFO config screen, tweaked the PRM a little bit in yaw, and was able to get a lock using REFL 165 I&Q for ~25 minutes before I got bored and unlocked things.  I used the ASS for the PRM to align the PRM, then turned off the ASS.  POP110 and POP22 both drifted down, but by a small amount, and at the end (when I turned the ASS back on for PRM), they picked back up to about their original levels.

PRMI_lock_ASSatBeginningAndEnd.png

(Note to self: to get it to print both plots, chose custom paper size, make it 14.5 by 11.  Don't ask why, just do it, because it works.  Also, in PNG device properties, increase the compression to 9.)

 

After I played with the PRMI, I started looking at the ALS system. 

I had both arms locked on IR using the regular LSC system (so POX and POY for the error signals).  Then I opened up the green shutters, and got both arms locked on green (so the green lasers were just following the arms...no digital ALS business).  I went out to the PSL table and tweaked up the alignment of the green beams (didn't need much at all, just an itsy bitsy bit in yaw, mostly).  I saw a very strong peak for the Yarm vs. PSL (around -19dBm), and there was a harmonic of that beat.  Opening and closing the Xarm green shutter had no effect on these peaks, so there wasn't any kind of X-Y cross beat sneaking around that I could see.  That's really as far as I got - I think (but haven't checked) that Manasa may have removed the power splitter / combiner, so that the RF analyzer is only looking at the Y beat PD (she mentioned earlier today that she was going to give that a try to narrow things down). 

After that, Rana and I went back to the PRMI for some noise stuff, and worked on the PMC.  See those separate elogs for info on those activites.

  9213   Mon Oct 7 13:55:26 2013 JenneUpdateLSCArms locked in IR for many hours

Someone left the arms aligned, and the LSC engaged, so the arms have been locked almost continuously for several days hours.  The trend below is for 4 days hours.  What is most impressive to me is that we don't see a big degredation in the transmitted power over this time.

EDIT: Okay, I got excited without paying attention to units.  It was only several hours, which is not too unusual.  Although the lack of transmission degredation is still unusual.  However, this may be due to improved oplevs?  I'm not sure why, but we're not seeing (at least in this plot) the degredation to ~0.7 after an hour or so.

BothArmsLocked3Days_7Oct2013.png

  9214   Mon Oct 7 14:15:10 2013 JenneUpdateLSCPRMI alignment is also excellent

Something is really excellent with the alignment today, or something has changed with the POP path / electronics.  While usually we see ~120 counts on POP22_I and ~175 counts on POP110_I (cf elog 9193), today I have ~175 counts on POP22_I and ~265 counts on POP110_I.

PRMI_excellent_alignment_7Oct2013.png

  9215   Mon Oct 7 14:24:10 2013 JenneUpdateLSCPRMI Config settings re-saved

I have resaved the PRMI locking settings in the IFO Config screen.  Nothing has changed, except that I have put a 1e-4 into the PRCL matrix elements for REFL11I, REFL33I and REFL55I.  So, PRMI still locks on REFL165 I&Q, but the other 3 REFL diodes' whitening gets triggered when the cavity is locked.  I think this will help the LSC sensing matrix measurements, which I'm going to test out now.

  9217   Mon Oct 7 18:36:39 2013 JenneUpdateLSCSensing Matrix scripts updated

I discovered that I was not getting enough SNR on all the refl RFPDs when I actuated using the Sensing Matrix script.  The problem was that the ITMs have actuation constants that are a factor of 5 lower than the PRM.  So, I need to push on the ITMs (for MICH) about 5 times as hard as I push on the PRM (for PRCL).  I have modified the sensing matrix scripts to allow different actuation amplitudes for each degree of freedom.  If I watch the REFL PD spectra while the script is running, I see that I now have some actual SNR (as in, more than 1, which is what the SNR was for some diodes previously). 

A consequence of this is that the script to analyze past data will no longer work on sensing matrix data taken before this afternoon.  On the other hand, that data isn't very useful, since there was no SNR.

  9218   Mon Oct 7 18:39:29 2013 JenneSummaryLSCPRMI: REFL11 beam realigned

Quote:

Bonus: notice how we have cleverly used the comb of bounce frequencies around the calibration line to determine that REFL11 is clipping!

 Rana and I noticed last week that it looked like the REFL11 beam was clipping.  This afternoon, I locked the PRMI with REFL 165 I&Q, and checked the REFL 11 path.  The beam looks fine through all of the optics going to the diode, so I just realigned the beam onto the diode using the itty bitty steering mirror.  I have not yet checked the change (hopefully improvement) in the REFL11 spectrum.

  9222   Tue Oct 8 16:56:38 2013 JenneUpdateLSCLSC model sensing matrix upgrades in progress

I have modified the LSC model (the currently-running model is checked into the svn), but it is not compiling for me.  So, if you need to make changes to it, be careful, and probably save my version off to the side, and checkout the latest svn version.  (I don't foresee anyone needing to modify this model any time soon though).

The change that I'm trying to make is adding several more lockin setups, so that we can measure the sensing matrix elements for several degrees of freedom simultaneously. 

Right now, the error that I'm getting is the frustrating "something isn't connected" error, even though if you look in the model, the part that it mentions is fully connected.  Usually the solution to this is to disconnect and reconnect everything, so I'll work on that after I return to the lab in a bit.

  9225   Wed Oct 9 17:27:35 2013 JenneUpdateLSCLSC model sensing matrix upgrades

The modifications to the LSC model are now complete, and the new model has been compiled, installed, and is running. The sensing matrix lockins are all in the c1cal model.  Masayuki is locking right now, so so far, things appear to be back to normal.

The longer version of the story, with all the detours and hiccups:

After several tries of deleting the GoTo and From flags / tags in the lockin area of the LSC model, and continually getting the "something is not connected" errors, I gave up and just drew several long lines.  So, in the new Sensing Matrix block (which is actually in c1cal, not c1lsc, but that's a story for the next paragraph), we should eventually make things back to the more clean flags situation, but for right now, it's working, with lots of lines everywhere.  I've tried to be very organized and clear about what lines go where, so that it's easy to see what's going on.

I eventually was able to compile c1lsc, and then installed it, and restarted the model.  Adding in 5x the lockin modules (we had 27, but now we have 5x27, so that we can look at the sensing matrix elements for every degree of freedom, and every photodiode, all at the same time) was too much for the poor lsc cpu.  I was consistently getting over 70usec per cycle, and was hitting a max of 77usec for the lsc cpu.  Both of those numbers are greater than the allowed 60usec.  So, I made the decision to put the whole sensing matrix / lockin stuff into the calibration model.  This means that I have 27+5 more IPC signals than I used to, but so far things seem to be okay (no rigorous testing yet).  (27 to send the 27 PD inputs over to the cal model, and another 5 to send the oscillator "clocks" from the cal model to the lsc model.)  The lsc model is now running faster than before (because there were 27 lockin modules in the model), at 24-28 usec, and the cal model is running at 39usec.

All seemed well and good, both the lsc and cal models compiled, but the lsc burt restore wasn't working.  Restarting the model did not successfully do a burt restore, and when I tried several different .snap files from today, and other times this month using burtgooey, I kept getting "NOT OK", and numbers weren't being restored into the epics channels.  A very few settings were restored, but most were not.  I ended up copying a .snap file from a few hours ago into a separate directory, then went in and by-hand removed all the lines referring to now non-existant lockin channels.  Burtgooey still told me "NOT OK", but settings seem to be restored, so I think it's okay.  I have not confirmed each and every one of the 10,000+ channels to ensure that the number is the same as the one in the .snap file, but as I glance around in the LSC screen and its dependants, all the numbers and buttons look about right.  

After all this stuff, Masayuki is locking both arms simultaneously in IR, as he prepares to test some new ALS scripts, so things seem okay for now.

  9227   Wed Oct 9 22:05:55 2013 JenneUpdateLSCNew lockin / sensing matrix screens

After finishing up working on the models for today, I made corresponding screens.  

The new Sensing Matrix (and lockin) overview screen is accessible from the sitemap:  LSC -> Sensing Matrix. 

From there, you have the oscillators, input matrices (one per degree of freedom), output matrix, and the lockin modules themselves.  You can either look at several PDs for one degree of freedom (ex. there is a screen for all the AS RFPDs, demodulated for the DARM oscillation), or all the degrees of freedom for a single PD (ex. how are all the degrees of freedom seen in AS55Q?).  The LSC screen has been updated to match - now you see 5 oscillator readbacks, and a larger output matrix.  There is a button for the Sensing Matrix overview screen, and if you click on the cartoons of the oscillators, it'll take you to the oscillators screen.

Still to do:

* Decide what 5 frequencies to use for excitation.

* Put the bandpass and lowpass filters into the lockin modules.

* Put matching notch filters into each LSC servo.

* Re-write the sensing matrix scripts.

* Put a little more stuff into the front end so that we get total mag and phase of the sensing matrix element, not just uncalibrated lockin outputs.

  9231   Thu Oct 10 11:46:43 2013 JenneUpdateSUSITMY OpLev Noise

For my work designing a cost function, so that I can try out new feedback servo designs on the oplevs, I wanted to know what the dark noise of an oplev is.  Since the pitch and yaw channels are divided by the sum channel, when the laser is off, the noise in the pitch and yaw channels looks much higher than it really is.  So, I collected some data from the 4 individual quadrants of the ITMY oplev, when the laser was on (but damping was off), and when the laser was off.  I used the values of the oplev input matrix to re-create the non-normalized pitch and yaw signals.  What I see is that we have some kind of real signal below 1 kHz, but we're hitting the noise at around 1 kHz.  So, we definitely don't want to use oplev error signal information above 1 kHz when designing new servos.

The last word in the title is "off".  OSEM damping was on, but the oplev damping was off.  These are uncalibrated, because the calibrations that we have to go from counts to microradians are for the normalized signals. 

ITMY_OpLev_Noise.png

  9234   Fri Oct 11 17:37:08 2013 JenneUpdateLSCNew lockin / sensing matrix screens

Quote:

Still to do:

* Decide what 5 frequencies to use for excitation.

* Put the bandpass and lowpass filters into the lockin modules.

* Put a little more stuff into the front end so that we get total mag and phase of the sensing matrix element, not just uncalibrated lockin outputs.

 I worked on some of these "to-do" things today for the new sensing matrix setup.  I chose several frequencies around 90 Hz for my measurements.  This was an area (while PRMI was locked with REFL 165 I&Q, and all 4 REFL PDs had their whitening on) there was a pretty wide clean space in the noise spectrum.

I put bandpass filters into the _SIG banks of the lockin modules, and lowpass filters into the _I banks.  However, when I loaded the new filter coefficients, it looks like not all of them are showing up in the screens.  I'm a little confused as to why.  They are still there if I close and re-open Foton, so I think I really put them in.

Also, I don't think that I'm successfully getting any signal from the LSC model into the new lockin modules on the CAL model.  I'm not sure if this is to do with the fact that I added 32 more IPC connections the other day.  I've emailed Jamie to ask whether or not we may have hit some limit.

I also tried testing out a small bit of c-code for the calibration of the lockin outputs.  It seems as though I cannot do an arctangent in the front end.  When I compile the c1tst model, and start it up, if I have an "atan2" in the code, it tells me "No Sync".  However, if I remove that line of c-code, the model compiles fine (which it did in the case with the arctan), and the model runs just fine (which it doesn't with the arctan).  My backup plan is to include a Taylor expansion for the arctangent in some c-code.

  9237   Mon Oct 14 17:40:15 2013 JenneUpdateLSCNew lockin / sensing matrix screens

 Hmmmm, yup.  I forgot to pay attention to what the UGFs of our LSC loops are when I was picking a low-noise region.  Since they're (currently, at least) around 100Hz, I want to find a frequency in the few hundred Hz region.  Masayuki has the IFO right now for ALS diagnostics, so I'll pick new frequencies later.   If we decide to omit the bandpass filters, it's even easier to change frequencies on the fly (although we'll always still have to make the servo notch filters match).

  9238   Mon Oct 14 17:51:40 2013 JenneUpdateIOOinput beam to PMC drifted again

Quote:

I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?

 The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.

I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.

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