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ID Date Author Type Categoryup Subject
  10733   Mon Nov 24 20:24:29 2014 diegoUpdateSUSAnti-Jitter Telescope for OpLevs

I stared a bit longer at the plots and thanks to Eric's feedback I noticed I payed too much attention to the comparison between Beta and Gamma and not enough attention to the fact that Beta has some zero-crossings...

I made new plots, focusing on this fact and using some real values for the focal lengths; some of them are still a bit extreme, but I wanted to plot also the zero-crossings for high values of x, to see if they make sense.


Plot of Beta and Gamma




Plot of Beta and Gamma (zoom)




If we are not interested in the sign of our signals/noises (apart from knowing what it is), it is maybe more clear to see regions of interest by plotting Beta and Gamma in absolute value:


Plot of Beta and Gamma (Abs)




I don't know if putting the telescope far from the QPD and near the mirror has some disadvantage, but that is the region with the most benefit, according to these plots.


The plots shown so far only consider the coefficients of the various terms; this makes sense if we want to exploit the zero-crossing of Beta's coefficient and see how things work, but the real noise and signal values also depend on the Alpha and Theta themselves. Therefore I made another kind of plot, where I put the ratio r'(Alpha)/r'(Theta) and called it Tau. This may be, in a very rough way, an estimate of our "S/N" ratio, as Alpha is the tilt of the mirror and Theta is the laser jitter; in order to plot this quantity, I had to introduce the laser parameters r and Theta (taken from the Edmund Optics 1103P datasheet), and also estimate a mean value for Alpha; I used Alpha = 200 urad. In these plots, the contribute of r'(r) is not considered because it doesn't change adding the telescope, and it is overall small.

In these plots the dashed line is the No Telescope case (as there is no variable quantity), and after the general plot I made two zoomed subplots for positive and negative focal lengths.


Plot of Tau (may be an estimate of S/N)




Plot of Tau (positive f)



Plot of Tau (negative f)



If these plot can be trusted as meaningful, they show that for negative focal lengths our tentative "S/N" ratio is always decreasing which, given the plots shown before, it does little sense: although for these negative f Gamma never crosses zero, Beta surely does, so I would expect one singular value each.

Attachment 2: 20141124_Plot_Real_BetaGamma_f_Zoom.pdf
Attachment 3: 20141124_Plot_Real_BetaGamma_Abs_f.pdf
  10738   Mon Dec 1 07:30:29 2014 SteveUpdateSUSETMX damping restored

ETMX sus damping restored and PMC locked manually.

  10753   Thu Dec 4 01:24:47 2014 JenneUpdateSUSPRM volin 3rd harmonic

Earlier this afternoon, while locking PRMI, I saw a big peak at 1883.48 Hz.  This comes closest to the PRM's 627.75 Hz *3, so I infer that it is the 3rd order harmonic of the PRM violin mode. 

While putting this in, I noticed that my addition of ETM filters the other day (elog 10746) had gotten deleted.  Koji pointed out that Foton can do this - it allows you to create and save filters that are higher than 20th order, but secretly it deletes them.  I went into the filter archive and recovered the old ETM filters, and split things up.  I have now totally reorganized the filters, and I have made every single optic (ETMs, ITMs, PRM, SRM, BS, MC2) all the same. 

FM1 is BS 1st and 2nd harmonics, and FM6 directly below that is a generic 3rd order notch that is wide enough that it encompases 3*BS. 

FM2 is the PRM 1st and 2nd order, and FM7 below it is the PRM 3rd order. 

FM3 is the SRM 1st order, FM4 is the ETMs' 1st order, and FM5 is the MC2 1st and 2nd order filters. 

All of these filters are triggered on if any degree of freedom is triggered.  They all have a ramp time of 3 sec. We may want to consider having separate trigger options for each optic, so that we're not including the PRM notch on the ETMs, for example, and vice versa. 

When all of these filters are on, according to Foton we lose 5.6 degrees of phase at 100 Hz.

  10757   Fri Dec 5 00:52:51 2014 JenneUpdateSUSETMX 2nd order violin

We looked at the spectra of POX and POY during IR lock, and Q saw a peak at 1285 in POX only.  We're actuating on the ETMs, so it must be an ETMX violin mode, although it doesn't match the others that are in the table.

Anyhow, I added it to FM9.  While I was doing that, I realized that yesterday I had forgotten to put back the 3rd order ETM violin notch, so that is also in FM9.

  10850   Sun Jan 4 12:49:18 2015 SteveUpdateSUSrecent earthquakes

All suspensions were tripped. Damping were restored. No obvious sign of damage. BS OSEM-UR may be sticking ?

Attachment 1: recentEQ.png
  10852   Mon Jan 5 12:42:09 2015 ericqUpdateSUSBS misbehaving

The BS was showing some excess motion. I think I've fixed it. Order of operations:

  • The DC PIT bias from previous ASS runs was at ~500, I zeroed this and aligned the BS to be centered on its oplev QPD with DC alignment sliders
  • I squished the gold box cables. This changed the alignment slightly, and brought the UR voltage back to a normal value. Excess motion still existed
  • I found that the the C1:SUS-BS_LRSEN filter had HOLD OUTPUT enabled. I turned it off. All seems well. 

I'm not sure how this might have gotten switched on...

  10870   Wed Jan 7 14:35:44 2015 diegoUpdateSUSSUS Drift Monitor

The SUS Drift Monitor screen has been updated:

  • removed the old dead channels from the MEDM screen;
  • updated the SUS models with new 'mute' channels where the expected values should be put;
  • updated the MEDM screen with the new channels
  • values are still 0 since I don't know what these expected values should be, at this time


  10881   Thu Jan 8 23:02:30 2015 diegoUpdateSUSSUS Drift Monitor

The MEDM screen has been updated: the new buttons, one for each optic, call the scripts/general/SUS_DRIFTMON_update_reference.py script, which measures (and averages) for 30s the current values of the POS/PIT/YAW drifts, and then sets the average as the new reference value.


  10882   Fri Jan 9 10:52:37 2015 SteveUpdateSUSPIT trend plots at the ends

100 and 10 days trends of ETMX and ETMY_SUSPIT.  One can see clearly the earthquaks of Dec.30 and 31 on the 10 day plot. You can not see the two shakes  M3.0 & M4.3 of Jan. 3 

The long term plot looks OK , but   the 10 day plot show the problem of ETMX as it was shaken 4 times.


Attachment 1: susPITends.png
  10924   Tue Jan 20 19:32:06 2015 JenneUpdateSUSSUS Drift restore scripts

I made little scripts to go with the sus driftmon buttons, that will servo the alignment sliders until the susyaw and suspit values match the references on the driftmon screen. 

  10930   Thu Jan 22 15:35:41 2015 diegoUpdateSUSBounce/Roll Measurements

I measured the bounce/roll frequencies for all the optics, and updated the Mechanical Resonances wiki page accordingly.

I put the DTT templates I used in the /users/Templates/DTT_BounceRoll folder; I wrote a python script which takes the exported ASCII data from such templates and does all the rest; the only tricky part is to remember to export the channel data in the order "UL UR LL" for each optic; the ordering of the optics in a single template export is not important, as long as you remember it...

Anyhow, the script is documented and the only things that may need to be modified are:

  • lines 21, 22: the "starting points" FREQ_B and FREQ_R (to accomodate noisy or bad data, as ETMX was for the Roll part in both the measurements I took);
  • line 72: the parameters of the slepian window used to average the data: the first one is the most important and indicates how much averaging will happen; more averaging means less noise but broader and lower peaks, which shouldn't be a big issue since we care only about the peak position, not its amplitude; however, if the peak is already shallow, too much averaging will make things worse instead of better;
  • lines 110, 118: the initial guess for the fit parameters;

The script is in scripts/SUS/BR_freq_finder.py and in the SVN. I attach the plots I made with this method.

Attachment 1: BR_Jan2015.tar.bz2
  10932   Thu Jan 22 22:15:30 2015 diegoUpdateSUSCentered OpLevs

[Diego, Jenne]

We centered the OpLevs for ITMX and ITMY.

  10934   Fri Jan 23 10:07:15 2015 SteveUpdateSUSSUS Drift ETMX vs ETMY

ETMX YAW stopped drifting Jan 8, 2015


I made little scripts to go with the sus driftmon buttons, that will servo the alignment sliders until the susyaw and suspit values match the references on the driftmon screen.

Attachment 1: SUSdrift30d.png
  10989   Mon Feb 9 08:40:49 2015 SteveUpdateSUSrecent earthquake 4.9

Baja 4.9 m earth quake tripped suspentions, except ETMX Sus damping recovered. MC is locking.

Attachment 1: M4.9Baja.png
  11088   Mon Mar 2 18:34:12 2015 JenneUpdateSUSETMX moving during single arm lock

This has been edited several times over the last several hours, as I try to change different parameters, to see if they affect the movement of ETMX.  So far, I don't know what is causing the motion.  If it is there, it is only present when the LSC is engaged, so I don't think it's wobbling constantly on a twisted wire.

FINAL EDIT, 9:10pm:  The arm ASC was turning itself on when the arms were locked.  Whelp, that was only 3 hours of confusion.  Blargh.

For his penance for leaving the arm ASC engaged, Q has made a set of warning lights on the LSC screen, right next to the ASS warning lights.

ETMX might be having one of those days today, which is lame. 

So far tonight, I have run the LSC offset script, set the FSS slow value to +0.2, and run the arm ASS scripts.  Nothing too crazy I think.

Sometimes when I lock the single arms, the ETMs move around like crazy.  Other times, not.  What is going on here???  The ETMs don't move at all when they are not being actuated on with the LSC.

In this screenshot you can see the end of a POX/POY lock stretch where everything was nice and good.  Then, the arms were unlocked, and they have a bit of a DC offset.  After settling from that step, they continue sitting nice and still.  Then, I relock the cavities on POX and POY a little before -4 minutes.  ETMY takes a moment to pull itself together, but then it's steady.  ETMX just wobbles around for several minutes, until I turn off the LSC enable switch (happened after the end of this plot). 

I'm not going to be able to lock like this.  Eeek! 

This is somehow related to light being in the Xarm.  This next plot was taken while the arms were held with ALS in CARM/DARM mode. 

  • Between -4 and -3, and again between -2 and -1.5, the arms were held with ALS "on resoanance".  Yarm power (green) is fine, Xarm power (purple) is not fine.  The ETMX OSEM pitch and yaw signals are bumpy at the same times.
  • Between -3 and -2 minutes, the arms were held with ALS off resonance.  Obviously you can't see anything about IR transmission, but you can see that the SUSPIT and SUSYAW signals quiet down. 
  • Between -1 and 0, I moved the Yarm ALS offset such that only it was resonating (the jags at the beginning of the resonance is me finding it, not to do with ETMY misbehaving). 
    • The ETMX SUS signals stay quiet. 
    • ETMY YAW has a DC offset when there is IR power in the arm.
  • After 0 minutes on this scale, I move the offsets such that only Xarm is "on resonance". 
    • The ETMX osem signals go bumpy again.

I closed and re-opened all 3 green shutters.  Now (at least the last 8 arm locks in the last 6 mintues) ETMX has never gone wobbly, except for a little bit right after acquisition, to deal with whatever the DC offset it. Why is this changing? 

The arms were fine for one long ~30 minute lock while I stepped out for dinner.  At some point after returned, the MC lost lock. When the arms came back, ETMX was being fussy again.  Then, it decided that it was done.

In this plot, at -1 minute I started the ASS.  Other than that, I did not touch any buttons at all, just observed.  I have no idea why at about -3 minutes the bad stuff seems to go away. 

I was curious if it had to do with the DC pointing of the optics, so I unlocked the arms, put ETMX about where it was during the long good lock stretch, then reaquired lock.  I had to undo a little of that so that it would lock on TEM00, but at the beginning of the lock stretch (starting at about -3) the pitch is about the same spot.  But, the oscillations persist.  This time it was clear that the oscillations were around 80 mHz, and they started getting bigger until they settled to an amplitude they seemed to like.

Seems pretty independent from FSS temp.  There are 3 lock stretches in the next plot (easier to see by looking at the Yarm transmission, green trace).  The first one, the FSS slow was at 0.35.  the middle one, it was around 0.05.  The last one, it was around -0.4.  Other than the different DC pointings (which I don't know if they are related), I don't see anything qualitatively different in the movement of ETMX.

Attachment 1: ETMX_moving.png
Attachment 2: ETMXmoving_ALSlock.png
Attachment 3: StartsMoving_stopsItself_ranASS.png
Attachment 4: 80mHz.png
Attachment 5: IndependFromFSStemp.png
  11092   Tue Mar 3 09:42:40 2015 SteveUpdateSUSETMX is drifting

The temperature of the east and south ends  are normal, they are about the same.


Attachment 1: ETMXdrifting.png
Attachment 2: ETMXvsTemp.png
  11100   Thu Mar 5 10:32:58 2015 SteveUpdateSUSBS oplev servo turned off

The BS oplev servo was kicking up the BS. It was turned off

  11104   Thu Mar 5 20:44:30 2015 JenneUpdateSUSdamprestore script updated

I just realized that the "damprestore" script that can be called from the watchdog screen did not have the new oplev names.  I have updated it, and added it to the svn.

  11142   Sat Mar 14 00:12:18 2015 ranaUpdateSUSOplevs huh?

The oplev situation still seems unresolved - notice this DTT. I guess there are still inconsistencies in the screens / models etc.

Could use some some investigation and ELOGGING from Eric.

Attachment 1: burp.png
  11148   Thu Mar 19 17:11:32 2015 steveSummarySUSoplev laser summary updated

           March  19, 2015   2  new  JDSU 1103P, sn P919645 & P919639 received from Thailand through Edmond Optics. Mfg date 12/2014............as spares

  11153   Fri Mar 20 23:37:46 2015 JenneUpdateSUSWaking up the IFO

In addition to (and probably related to) the XARM ASS not working today, the ITMX has been jumping around kind of like ETMX sometimes does.  It's very disconcerting. 

Earlier today, Q and I tried turning off both the LSC and the oplev damping (leaving the local OSEM damping on), and ITMX still jumped, far enough that it fell off the oplev PD. 

I'm not sure what is wrong with ITMX, but probably ASS won't work well until we figure out what's up.

I tried a few lock stretches (after realigning the Xgreen on the PSL table) after hand-aligning the Xarm, but the overall alignment just isn't good enough.  Usually POPDC gets to 400 or 450 while the arms are held off resonance, but today (after tweaking BS and PRM alignment), the best I can get POPDC is about 300 counts. 

Den and I are looking at the ASS and ITMX now.

  11155   Sun Mar 22 13:53:44 2015 ranaUpdateSUSITMX alignment jumps

So, was there real shifting in the ITMX alignment as seen in the DV trend or just mis-diagnosis from the ETMX violin mode? Or how would the ETMX violin mode drive the ITMX with the LSC feedback disabled?

  11160   Mon Mar 23 13:27:33 2015 ericqUpdateSUSITMX oplev quadrant gains unbalanced

I've been poking around the oplev situation. One thing I came across regarding ITMX was that the gain on segment 4 seems to be about higher than the other segments. I was led to believe this by steering the optic around, and looking at the counts on each quadrant when the other 3 were dark.

Putting a gain of 0.86 (the ratio of the other segments' max counts over segment 4's max counts) in the segment 4 FM flattens the 1 Hz peak in the ITMX_OL_SUM spectrum, as well as significantly reducing the sub-Hz coherence of the sum with the individual quandrant counts. This is what I would expect from reducing the coupling of angular motion due to quadrant gain mismatch into the sum. 

Here are the ITMX_OL_SUM spectra before and after (oplev servos are off).

The "burps" and control filter saturations are still unexplained. Investigations continue...

Attachment 1: olsum.png
  11198   Fri Apr 3 10:46:32 2015 SteveUpdateSUSOSEM sensor oscillation

ITMX, ETMY, BS and SRM are oscillating ?

Attachment 1: sensors1sec.png
  11199   Fri Apr 3 14:57:38 2015 manasaUpdateSUSBS oplev

The BS oplev has been misbehaving and kicking the optic from time to time since noon. The kicks are not strong enough to trip the watchdogs (current watchdog max counts for the sensors is 135).

I took a look at the spectrum of the BS oplev error in pit and yaw with both loops enabled while the optic was stable. There is nothing alarmingly big except for some additional noise above 4Hz.

I have turned the BS oplev servo OFF for now.

Attachment 1: BS_oplev_Apr3.png
  11200   Fri Apr 3 15:15:55 2015 SteveUpdateSUSBS oplev

I saw this kicking before  


The BS oplev has been misbehaving and kicking the optic from time to time since noon. The kicks are not strong enough to trip the watchdogs (current watchdog max counts for the sensors is 135).

I took a look at the spectrum of the BS oplev error in pit and yaw with both loops enabled while the optic was stable. There is nothing alarmingly big except for some additional noise above 4Hz.

I have turned the BS oplev servo OFF for now.


  11201   Fri Apr 3 19:35:14 2015 JenneUpdateSUSBS oplev centered

I think that this happens when the beam gets too close to the edge of the QPD.  We see this regularly in the ETMs, if they've been kicked a bit, but not enough to trip the watchdogs.  I think it might be the step/impulse response of the RES3.3 filter, which rings for almost 20 seconds. 

Anyhow, I've just recentered the BS oplev.  It was at -21urad in pitch, and had more than 400 counts on the top two quadrants, but only about 100 counts on the bottom two.  Now it's around 300 counts on all 4 quadrants.

As a totally unrelated aside, I have installed texlive on Donatella, so that I could run pdflatex.

  11227   Mon Apr 20 16:42:48 2015 steveUpdateSUSPRM and BS oplev laser replaced

The laser below is dead. JDSU 1103P, SN P845655 lived for 3.5 years.



JDSU 1103P died after 4 years of service. It was replaced with new identical head of 2.9 mW output. The power supply was also changed.

The return spots of 0.04 mW  2.5 mm diameter on qpds are BS  3,700 counts and PRM 4,250 counts.


It was replaced by JDSU P/N 22037130,( It has a new name for 1103P Uniphase ) sn P919639 of mfg date 12-2014

Beam shape at 5 m nicely round. Output power 2.8 mW of 633 nm

BS spot size on qpd ~1 mm &  60 micro W

PRM spot size on qpd ~1 mm & 50 micro W

Attachment 1: newOplevLaser.png
  11234   Wed Apr 22 11:43:28 2015 SteveUpdateSUSETMX damping restored

ETMX sus damping restored.

  11246   Fri Apr 24 23:40:15 2015 ranaUpdateSUSPRM and BS oplev laser replaced

Recently, Steve replaced the HeNe which was sourcing the BS & PRM OL. After replacement, no one checked the beam sizes and we've been living with a mostly broken BS OL. The beam spot on the QPD was so tiny that we were seeing the 'beam is nearly the size of the segment gap' effect.

Today I removed 2 of the lenses which were in the beam path: one removed from the common PRM/BS path, and one removed from the PRM path. The beams on both the BS & PRM got bigger. The BS beam is bigger by a factor of 7. I've increased the loop gains by a factor of 6 and now the UGFs are ~6 Hz. The loop gains were much too high with the small beam spots that Steve had left there. I would prefer for the beams to be ~1.5-2x smaller than they are now, but its not terrible.

Many of the mounts on the table are low quality and not constructed stably. One of the PRM turning mirror mounts twisted all the way around when I tried to align it. This table needs some help this summer.

In the future: never try locking after an OL laser change. Always redo the telescope and alignment and check the servo shape before the OL job is done.

Also, I reduced the height of the RG3.3 in the OL loops from 30 to 18 dB. The BS OL loops were conditionally stable before and thats a no-no. It makes it oscillate if it saturates.

Attachment 1: BSOL.pdf
  11256   Sun Apr 26 15:34:34 2015 JenneUpdateSUSPRM oplev centered

After last week's work on the BS/PRM oplev table, I think the PRM oplev got centered while the PRM was misaligned.  With the PRM aligned, the oplev spot was not on the QPD.  It has been centered.

  11319   Fri May 22 11:59:54 2015 ericqUpdateSUSDampRestore script problem

PRM watchdog tripped, but the damprestore.py script wouldn't run. 

It turns out the script tries to import some ezca stuff from /users/yuta (angry), which had been moved to /users/OLD/yuta (crying). 

I've moved the yuta directory back to /users/ until I fix the damprestore script. 

  11320   Fri May 22 12:09:57 2015 ranaUpdateSUSDampRestore script problem

I will move it back. We need to fix our scripts to not use any users/ libraries ever again.


PRM watchdog tripped, but the damprestore.py script wouldn't run. 

It turns out the script tries to import some ezca stuff from /users/yuta (angry), which had been moved to /users/OLD/yuta (crying). 

I've moved the yuta directory back to /users/ until I fix the damprestore script. 


  11339   Mon Jun 1 08:32:14 2015 SteveUpdateSUSPRM damping restored

Local earthquake 3.8 Mag tripped only PRM

Vac monitor is not communicating.

PSL HEPA turned on

Attachment 1: indio3.8Meq.png
  11349   Tue Jun 9 10:57:12 2015 SteveUpdateSUS BS oplev laser tuned

Lenses removed from oplev beam path at elog entry 11246


Attachment 1: 100dBStrend0425.png
Attachment 2: 18dBSdrift.png
  11476   Mon Aug 3 08:16:19 2015 SteveUpdateSUSETMX damping restored
Attachment 1: ETMXrestored.png
  11525   Mon Aug 24 14:05:47 2015 ericqUpdateSUSEricG Investigating L2A

This afternoon, I showed Eric Gustafson some of the basics of making swept sine measurements with DTT. We turned off the f2a filters and oplev damping on the BS and made a cursory measurement of the transfer function from position drive to the oplev signals. 

He will be in the lab periodically to continue this line of investigations. 

  11526   Mon Aug 24 16:10:07 2015 ericqUpdateSUSETMY Oplev laser power is falling

Today I noticed the box around the ETMY oplev sum flashing red, as it dipped below 1k. I don't recall seeing this recently, so I wanted to look up the history.

However, we've been having trouble with our minute (and longer) trend data, so I had to hack it out a bit... Here is the unfortunate result:

I think we can be fairly confident that this is not due to alignment drifts, we generally keep the QPD reasonably well centered. I also recentered it today, and the counts remained at ~1k. 

Details of the hack that got me this data:

I ended up looking at the BURT snapshots from every night at midnight, which report a number for ETMY_OL_SUM_OUT16, and making a text file with dates and values with the following BASH spaghetti:

find /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2015 -wholename "*00*/*scy*" |xargs ack --nogroup "ETMY_OL_SUM_OUT16 1" |  sed -e 's/.*2015/2015/g' -e 's/\/c1.*\([0-9]\..*$\)/, \1/g' -e 's/\//-/g'  > ETMYsum.txt

This produces a file full of unsorted lines like: 2015-Aug-23-00:07, 1.106459228515625e+03

The python package pandas is good at parsing dates and automatically plotting time series: 

olsum = pandas.read_csv('ETMYsum.txt', index_col=0, parse_dates=True)
Attachment 1: ETMYsum_trend.pdf
  11527   Mon Aug 24 16:46:49 2015 ericqUpdateSUSETMY Oplev laser power is falling

Repeated for all optics, ETMY seems like the only one sharply dropping for now (PRM is all over the place and hard to gauge, since we often leave it partially- or mis-aligned):


Hacky bits:


find /opt/rtcds/caltech/c1/burt/autoburt/snapshots/2015 -wholename "*00:0*"
| xargs ack --nogroup "OL_SUM_OUT16 1"
| grep -v 'SUS-MC'
| sed -e 's/.*2015/2015/g' -e 's/\/c1.*C1:SUS-/, /g' -e 's/_OL.*\([0-9]\..*$\)/, \1/g' -e 's/\//-/g'
| sort | uniq > allOL.txt

qontrols@pianosa|~ > head allOL.txt 
2015-Apr-10-00:07, BS, 1.146766113281250e+03
2015-Apr-10-00:07, ETMX, 1.597261328125000e+04
2015-Apr-10-00:07, ETMY, 4.331762207031250e+03
2015-Apr-10-00:07, ITMX, 6.488521484375000e+03
2015-Apr-10-00:07, ITMY, 1.387590234375000e+04
2015-Apr-10-00:07, PRM, 8.352053833007812e+02
2015-Apr-10-00:07, SRM, 6.099560928344727e+01
2015-Apr-1-00:07, BS, 1.180478149414062e+03
2015-Apr-1-00:07, ETMX, 1.584842480468750e+04



olsum = pd.read_csv('allOL.txt',parse_dates=True, names=['Date','Optic','Sum'])
olsum['Date'] = pd.to_datetime(olsum['Date']) # Automatic parsing didn't work for some reason
olpivot = olsum.pivot(index='Date',columns='Optic',values='Sum')
Attachment 1: OLsum_trend.pdf
  11566   Thu Sep 3 08:53:55 2015 SteveUpdateSUSETMY Oplev laser power is falling

Rana, Steve

We investigated the ETMY oplev table set up and did not find a red herring.

Two 2 years  vs one day plot below.

ps: thanks  Q for fixing  DTT, the auto scaling is not working at sampling rate 10 min and 1 hr period?? surprise


Attachment 1: ETMYoplev2y.png
  11569   Thu Sep 3 19:52:24 2015 ranaSummarySUSSUS drift monitor

Since Andrey's SUS Drift mon screen back in 2007, we've had several versions which used different schemes and programming languages. Diego made an update back in January.

Today I added his stuff to the SVN since it was lost in the NFS disks somewhere. Its in SUS/DRIFT_MON/.

Since we've been updating our userapps directory recently to pull in the screens and scripts from the sites, we also got a copy of the Thomas Abbott drift mon stuff which is better (Diego actually removed the yellow/red functionality as part of the 'upgrade'), but more complicated. For now we have the old one. I updated the good values with all optics roughly aligned just a few minutes ago.

Attachment 1: 07.png
  11642   Fri Sep 25 11:08:33 2015 SteveUpdateSUSwire standoffs

Our last effort to change the existing Al-6061 wire standoffs was at April 2012

We requested sapphire and/or ruby materials with smaller R at the bottom of the  groove. Groove polishing was asked for.

Insaco Inc. quote 84740 as " best effort " NO POLISHING.  The groove cut to be with eximer laser.

Jeff Lewis as 9-12-2012:  the LIGO sapphire prisms grooves were NOT POLISHED  but Resonatics used the corner of a rasor blade to scrape off the

ablated material wich was redeposited in and around the grooves.

Attachment 1: wireStandOff_SOS.PDF
  11643   Fri Sep 25 14:52:08 2015 SteveUpdateSUSETMX is not drifting

We have talked about the drift of ETMX sus on the Wednesday meeting.

It has stopped moving on Jan 8, 2015 and it has been reasanable stable since than.


Attachment 1: ETMXstoppedDrifting.png
Attachment 2: 25daysArmsT.png
  11646   Fri Sep 25 19:06:13 2015 ranaUpdateSUSETMX IS drifting

I don't see any evidence of it getting more stable. It seems there was a big step in January, but the problem we were talking about - the suspension shifting when it gets a big kick - can't be proven to be gone or not by just looking at the trends. The real issue is whether or not it slips when we put in a large step in the LSC.


We have talked about the drift of ETMX sus on the Wednesday meeting.

It has stopped moving on Jan 8, 2015 and it has been reasanable stable since than.


  11667   Mon Oct 5 11:25:21 2015 ericqUpdateSUSETMY OL laser dead

Gautam alerted me that the Y arm looked like it was being dithered, even though the ASS was turned off. I found that the ETMY OL signals were garbage, leading to the servos flipping back and forth between their rails. 

We went out to the ETMY table, and found the HeNe laser to be emitting a paltry <0.5mW; the OL QPD could not register the puny beam incident on it.

Here is the last 30 days of OL_SUM:

Steve will replace the laser this afternoon. 

  11668   Mon Oct 5 16:41:22 2015 SteveUpdateSUSETMY OL laser replaced

This JDSU 1103P laser, sn P892324 lived for 2 years. It's power output is 0.05 mW now

It was replaced with brand new JDSU 1103P,  sn P919645, Mfg date 12/2014 with 2.75 mW output.

There is 0.14 mW  light returning to the qpd = 7,250 counts without AR 632 lenses

  11702   Tue Oct 20 15:51:44 2015 ericqUpdateSUSMC2 F2P tuned

Using a modified version of Hang's deMod_deCoup scripts, I tuned the MC2 coil output matrix to minimize the appearance of POS drive in the SUSPIT signal at 28Hz. Up until now, there was no F2P compensation. This reduced the force to pitch coupling at 28Hz by 8dByes

Old: POS -> 1 x UL, 1 x UR, 1 x LL, 1x LR

New: POS -> 1.1054 x UL, 1.1054 x UR, 0.8946 x LL, 0.8946 LR

I checked the MCL spectrum before and after this change with OAF on, this did not spoil the feedforward length subtraction in any noticible way. 

The script lives in userapps/release/isc/c1/scripts/decoup, but I've symlinked it to /opt/rtcds/caltech/c1/scripts/decoup.

The script modification I made had to do with how the I and Q data is collected. Before, it was sporadically probing the I and Q FM output monitor EPICS values; I changed it to use the avg function of cdsutils, which calculates the mean and std from the 16kHz data and have seen it improve results by 1dB or so. I've been in touch with Jenne to propagate this to the sites. 

  11711   Fri Oct 23 21:58:10 2015 ranaUpdateSUSMC2 F2P mis-tuned

The OSEMs cannot be used for coil balancing above ~10 Hz. The main coupling path from OSEM drive to sensor is not through the mirror motion, but instead direct electrical coupling of the drive wires to the sensing wires.sad

I put this in the elog every ~1-2 years since people keep trying it, but it keeps coming back like a zombie.crying

Better to use the MC angular sensors for L2A decoupling. Not perfect, but better than OSEMs. For the TMs we can use the OLs.

  11716   Tue Oct 27 03:46:26 2015 ericqUpdateSUSMC2 F2P mis-tuned

D'oh. Good point.

Reverted for now; I'm thinking about doing laser pointer->MC2 QPD...

  11724   Fri Oct 30 17:49:27 2015 SteveUpdateSUSETMX kicked up

The oplev and  the LSC are off.

Attachment 1: ETMXkicking.png
Attachment 2: ETMXkickedbyOpPerror.png
Attachment 3: ETMXstillKicking.png
Attachment 4: ETMXkickingCond.png
Attachment 5: 7hrsETMX-Y.png
ELOG V3.1.3-