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ID Date Authorup Type Category Subject
  8609   Tue May 21 18:22:18 2013 JenneUpdateLSCSensing matrix scripts modified to include actuator calibration

The PRMI sensing matrix scripts have been modified to output a sensing matrix which is calibrated into units of counts/meter.

To run, you should just need to run .../scripts/LSC/runPRMI_SENS.py . 

If it looks like the drive amplitude is not large enough (no nice peak in the photodiode signals), you can increase the drive amplitude, which is line 21 in runPRMI_SENS.py  

  8618   Wed May 22 17:29:34 2013 JenneUpdateASCQPD for POP ASC tested

I fiddled around with the QPD that I'll use to replace Koji's temporary razor blade yaw sensor for detecting POP beam angular motion, and checked that it is working. 

Using the Jenne Laser, I put beam onto the 4 different quadrants of the QPD, and saw that the Sum channel remained constant. 

   * I had the room lights off, since the PD elements are silicon. 

   * Beam size on the QPD as seen on an IR card was ~1mm diameter.

   * With the beam on the QPD, I chose gain setting "G2" on the amplifier, since that was the only setting where neither the "current too high" nor the "current too low" LEDs were illuminated.  I didn't measure the power going to the PD, but the Jenne Laser puts out 1.2mW, and there's a 50/50 BS, so I was getting about 600uW. 

   * I turned off the "zero/cal" switch on the back of the box, since I don't know how to set the zero.  Since the X and Y channels are normalized by the Sum, you can't just block all light going to the PD and set the zero.  There isn't a big change in the output levels with the zero/cal switch off, so I think it should be fine.  (Previously, I set all 4 knobs - "zero" and "cal" for each X and Y - to approximately the center of their ranges.  Once you hit the end of the range, you can keep turning the knob, but something inside makes a clicking sound ~once per revolution, and the signal level stops changing (for the zero knobs). Much like centering a beam on a PD, I found each edge of the range for each knob, and set the knobs in the centers by counting the number of turns.  Anyhow, since I set the knobs to ~halfway, I think that explains why there isn't really a change whether the "zero/cal" switch is on or off.

   * Using the steering mirror sending the beam to the QPD, I moved the beam around, and watched where I was going with an IR viewer.  I see that as I move from quad-to-quad, the X and Y channels respond as I expect.  If I only move the beam in X, I only see X response on a 'scope, and vice versa.

I can't do a real calibration until I get the QPD installed in place, so I can use the actual beam, but for now it looks like the QPD is responding nicely.  Since Annalisa and Manasa are using the Arms for the evening, I'll work on putting the QPD on the POX table tomorrow.

  8619   Wed May 22 18:07:36 2013 JenneUpdateLSCKiwamu's sensing matrix measurement script revived

 

 To avoid exciting at the PRM violin mode frequency, I have changed all of the filters relevant to the sensing matrix measurement from 628Hz to 580.1Hz.  This includes notches in the LSC control loops, as well as the band pass filters in the lockins.  I have not yet loaded the new filters, since arm locking is in progress.

 

  8620   Wed May 22 18:24:19 2013 JenneUpdateSUSViolin mode survey

Quote:

It was too embarassing to see that the actuation frequency was set at the violin mode frequency in order to avoid designing a new filter!?

 Ooops, definitely my bad.  I think I was the one who put in the PRM violin filter, so I should have recognized that frequency.  However, I couldn't think of a reason why violin mode filters should be in the LSC filter banks, since we usually put them in C1:SUS-optic_LSC filter banks. 

Anyhow, so that I don't make a mistake like that again, I was looking through all of the violin mode filters for all the optics, so I could write down the frequencies.  The result: confusion.

Violin filters in C1:SUS-optic_LSC filter banks:

The PRM's violin mode filter is set correctly to 627.75Hz:  elog 8533.

One of BS or SRM has probably been measured (presumably BS), since they have the same filters centered around 645Hz. 

Neither ITM has a violin filter.

The ETMs have violin filters in the 440's, which I assume was correct back in the MOS days, before 2010.

Vio2 filters in C1:SUS-optic_LSC filter banks:

PRM, SRM, BS, ITMX, ITMY:  Centered around 1285 Hz, which matches the violin notch frequencies in the BS and SRM.

ETMY:  Centered around 883.5Hz, which matches the old 440Hz frequency

ETMX:  Centered around 631Hz .  So, this could have been measured, but it was put into the wrong filter module.

 

Koji tells me that we don't really need to worry about all these violin filters unless they are required (as with the PRM and the obnoxious hum a few weeks ago), so I 'm not going to do any measuring / adjusting of these filters for now.

  8621   Wed May 22 20:50:26 2013 JenneUpdateLSCSensing matrix scripts don't calculate correctly

I am trying to re-analyze the data that Koji took last night.  

I think that my script is just pulling out the I and Q data for each port, and each degree of freedom, calculating the magnitude from sqrt( I**2 + Q**2 ) and the phase from atan2( I / Q ).  No calibration.

If I print out the results, I get:

Sensing Matrix, units = cts/ct, phase in degrees
 
            MICH Mag   MICH Phase    PRCL Mag   PRCL Phase  
AS55_I      1.627E-02   62.063        4.189E-03   68.344       
AS55_Q      2.073E-02  -105.353        1.983E-02   66.361       
REFL11_I    8.165E+02  -112.624        2.441E+00   77.911       
REFL11_Q    2.712E+02  -112.650        7.065E-01  -127.093       
REFL33_I    8.028E+00  -112.154        6.282E-02   70.990
       

REFL33_Q    5.490E-02  -165.912        9.908E-03   61.269       

REFL55_I    8.347E+00  -112.085        2.146E-02   78.928       
REFL55_Q    3.003E-01  -151.652        7.924E-02   87.153
 

If, however, I take the raw values that are stored in the data file, for one row (say, REFL33_Q) and calculate by hand (same formulas), I get different results:

            MICH Mag   MICH Phase    PRCL Mag   PRCL Phase  
REFL33_Q    9.9E-03    28.89         5.46E-02   -103.8

Contrast that with Koji's uncalibrated transfer function result from elog 8611:

            MICH Mag    MICH Phase    PRCL Mag     PRCL Phase  
REFL33Q     1.8665e-5   71.1204      
1.6310e-4    -141.73

 

I am currently confused, and need to re-look at my script, as well as make sure I am actually measuring the things I think I am.

EDIT:  This has been fixed, in that my 2 calculations agree with one another.  I have crossed out the incorrect numbers, and put correct numbers below.  I still don't agree with Koji, but at least I agree with myself. 

The phase issue:  I needed to calculate the phase with "ATAN2(I,Q)", which I did when I calculated by hand, but the script had "atan2(Q,I)".  This has been fixed. 

The magnitude issue:  They match, but my "pretty print" script labels MICH as PRCL, and vice versa.  Doh.

Corrected values:

Sensing Matrix, units = cts/ct, phase in degrees
 
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
AS55_I      1.627E-02    27.937      4.189E-03    21.656     
AS55_Q      2.073E-02  -164.647      1.983E-02    23.639     
REFL11_I    8.165E+02  -157.376      2.441E+00    12.089     
REFL11_Q    2.712E+02  -157.350      7.065E-01  -142.907     
REFL33_I    8.028E+00  -157.846      6.282E-02    19.010     
REFL33_Q    5.490E-02  -104.088      9.908E-03    28.731     
REFL55_I    8.347E+00  -157.915      2.146E-02    11.072     
REFL55_Q    3.003E-01  -118.348      7.924E-02     2.847 

  8623   Thu May 23 00:49:13 2013 JenneUpdateLSCLSC filters loaded

Quote:

 To avoid exciting at the PRM violin mode frequency, I have changed all of the filters relevant to the sensing matrix measurement from 628Hz to 580.1Hz.  This includes notches in the LSC control loops, as well as the band pass filters in the lockins.  I have not yet loaded the new filters, since arm locking is in progress.

 I have loaded these new filters in.  Manasa is still using the IFO for green stuff, so I can try out the PRMI measurement in a day or so.  (Right now I have to make sure I understand my data, anyway.)

  8630   Thu May 23 14:45:08 2013 JenneUpdateLSCSensing matrix scripts calculations make more sense now

I think I have most of the magnitude issues figured out now. 

First of all, the lockin outputs are different from the actual responses in the PDs by a factor of 2. 

If the optic is driven with amplitude D, it will have a response of Asin(wt) + Bcos(wt) + other frequency junk.  The lockin bandpasses the response to get rid of the 'other frequency junk'.  Then creates 2 new signals, one multiplied by cos(wt), the other multiplied by sin(wt).  So, now we have Asin^2(wt) + Bcos(wt)sin(wt) and Asin(wt)cos(wt) + Bcos^2(wt).   If I rewrite these, I have A/2*(1-cos(2wt))+B/2*(sin(2wt) and A/2*sin(2wt)+B/2*(1+cos(2wt)).  We lowpass to get rid of the 2w components, and are left with A/2 for the Q-phase, and B/2 for the I-phase of the lockin outputs.  Since the real amplitudes of the response were A for the Q-phase and B for the I-phase, we need to multiply the lockin outputs by 2.

The other problem was that in the 'uncalibrated' version of numbers that I was printing to compare with Koji's, I had not normalized by the drive amplitude yet.  That happens in the "calibration" part of my script.  So, if I go back to comparing the calibrated versions of our numbers, I get quite close to Koji's answers.

For the PRCL magnitudes, 3 of the 4 numbers match to ~5%.  However, the MICH magnitudes all seem to be off by a factor of 2.  I'm still stuck on this factor of 2, but I'm thinking about it. Also, the phases that Koji and I get are pretty different.

Koji's sensing matrix:

Sensing Matrix, units = cts/meter, phase in degrees
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
REFL33_I    3.100E+11  -109.727      4.900E+09    74.434     
REFL33_Q    3.300E+09  -141.730      7.900E+08    71.120     
REFL55_I    3.200E+11  -109.672      5.900E+08    77.313     
REFL55_Q    1.200E+10  -143.169      6.500E+09    91.559  

My sensing matrix:

Sensing Matrix, units = cts/meter, phase in degrees
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
REFL33_I    3.242E+11  -157.846      1.067E+10    19.010     
REFL33_Q    2.217E+09  -104.088      1.683E+09    28.731     
REFL55_I    3.371E+11  -157.915      3.645E+09    11.072     
REFL55_Q    1.213E+10  -118.348      1.346E+10     2.847

Here are the plotted versions of these matricies:

SensMat_KojiMeas_23May2013.png

SensMat_JenneMeas_23May2013.png

SOME EDITS:  Koji's measurement was 1Hz away from the violin mode, while mine (him running my script) was at the violin mode, so the sensor TFs were actually taken at slightly different frequencies. This helps explain the discrepancies.

Also, the phase in these plots isn't correct, so I need to figure that out. Corrected version of the 'koji' measurement put in place of the incorrect one.  I convert from radians to degrees for my script, but Koji had already reported his phases in degrees, so when I multiplied by 180/pi, it didn't make any sense. I now convert his numbers to radians before running them through my analysis script.

 

  8632   Thu May 23 19:09:15 2013 JenneUpdateLSCSensing matrix scripts modified to include actuator calibration

After fixing up my calculations in my scripts, I have calculated the final PRMI sensing matrix (as measured very close to the violin frequency, so things may not be perfect). The data is from the file that Koji mentioned in his elog when he did the measurement:  elog 8611, sensematPRM_2013-05-22.12615.dat

Sensing Matrix, units = cts/meter, phase in degrees
 
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
AS55        1.064E+09   141.880      3.442E+09    11.929     
REFL11      3.474E+13  -108.372      4.316E+11   106.143     
REFL33      3.242E+11   -90.392      1.080E+10    81.037     
REFL55      3.373E+11   -92.060      1.394E+10    15.153 

SensMat_21May2013.png

In the plot, the little blobs on the ends of the 'sticks' are the error blobs.  Many of them are smaller than is really visible - this is good.  These errors come from measuring the lockin outputs several times while there is no drive to any optics, then the errors are propagated to each degree of freedom.  These errors do not incorporate any information about the precision of the actuator calibration, and they assume that the shape of all the sensor transfer functions are the same. 

If you look at the REFL11 and REFL33, it kind of seems like a miracle that we've ever been able to lock the full PRMI with the I&Q signals from either PD!

  8633   Thu May 23 20:39:50 2013 JenneUpdateLSCPRMI sensing matrix measured at 580.1Hz

I locked the PRMI and remeasured the sensing matrix, this time at 580Hz.  The excellent news here is that the matrix looks quite similar to the one measured the other day, recorded in elog 8632.  Yay!  I'm not sure why the REFL11 MICH error is so much larger this time around.

Raw data:  .../scripts/LSC/SensMatData/sensematPRM_2013-05-23.202312.dat

Sensing Matrix, units = cts/meter, phase in degrees
 
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
AS55        5.485E+08   162.424      2.679E+09    25.608     
REFL11      1.126E+13  -122.832      1.618E+11    85.296     
REFL33      2.658E+11   -87.973      8.910E+09    79.226     
REFL55      3.012E+11   -99.534      1.210E+10    12.486 

     SensMat_23May2013.png

  8634   Thu May 23 20:58:49 2013 JenneUpdatePEMPRM, ITMX optics tripped, restored

M5.7 - 11km WNW of Greenville, California

Time
Location
40.190°N 121.064°W
Depth
0.0km
  8635   Thu May 23 21:45:51 2013 JenneUpdateLSCSensing matrix scripts now check for lockloss

A few more small mods to the sensing matrix script.  Now the script saves the data after each measurement, so that in case you lose lock and can't measure any more, you still have the data you already measured.  Also, the error bar measurements are last, so that the consequence of losing lock partway through the measurement is just that you get fewer error bar numbers.  Not a big deal, since the actual sensing matrix data is already saved.

Also, the old script had a lockloss checker that I had overridden since it wasn't where I wanted it.  I have now re-implemented it, so that the script will stop the oscillation and quit measuring if either the LSC enable switch is off, or the degrees of freedom you're trying to measure are not triggered.  All data saved before the lockloss is saved though (as mentioned above).

  8640   Fri May 24 13:41:19 2013 JenneUpdateLSCPRMI sensing matrix measured at 580.1Hz

"0 degrees" is 0 degrees of demod phase.  I have now added the PD demod phases to the plot:

SensMat_23May2013_withIQ.png

  8642   Fri May 24 14:40:22 2013 JenneUpdateLSCPRMI sensing matrix: now what?

Quote:

It's hard to believe but is AS55Q really almost insensitive to MICH?

Well, anyway, now it is the time to use the automatic demod phase (and input matrix) adjustment.

 I am also wondering if I understand / am using the demod phase from the screen correctly.  This plot is indicating that MICH is entirely in I, and not at all in Q.

Currently, I take the demod phase, and plot that as the "I" line, then plot the "Q" line 90 degrees away from the I line.  Maybe it should be the other way around?

Re: the auto-demod phase, I was starting to wonder about that.  For each sensor, can I declare what degree of freedom I want in which quadrature to take priority (ex. MICH goes to REFL55 Q), and set the demod phase to the value that makes that true?

  8643   Fri May 24 14:44:34 2013 JenneUpdateGeneralRossa freezes all the time

I am getting tired of having to restart Rossa all the time.  She freezes almost once per day now.  Jamie has looked at it with me in the past, and we (a) don't know why exactly it's happening and (b) have determined that we can't un-freeze it by ssh-ing from another machine.

I wonder if it's because I start to have too many different windows open?  Even if that's the cause, that's stupid, and we shouldn't have to deal with it.

\end{vent}

  8644   Fri May 24 22:18:33 2013 JenneUpdateLSCPRMI sensing matrix: Got it!

Okay, I think I am finished with the sensing matrix scripts!  

I had the syntax for atan2() wrong, so I was calculating the demod phase wrong.  Do not trust the phase in any previous elogs!!

Also, the theta=0 axis of the plots are for 0 degree demod phase, but our PDs are not at 0 deg.  The measured sensing matrix phase is relative to the current demod phase, not 0 (unless the demod phase for that PD is currently 0degrees).  So, now I take that into account.  I add the current PD demod phase to the measured sensing matrix phase, so that the plot is actually true.

For interested parties, I have made all of the sensing matrix scripts, and the data folder a subdirectory of the /scripts/LSC folder, since it was starting to get crowded in there.  I have moved the 2 data sets that have been collected (21May, 23May) into the new place.

Future thoughts: 

* Save the amplitude and modulation frequency and the current demod phases in the data file.  Right now the ampl and mod freqs are included in the title of the data file, but there is no record of what the demod phase was at the time.  I need to fix this.

 

So, really, really, the Sensing Matrix:

Sensing Matrix, units = counts/meter, phase in degrees
 
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
AS55         5.485E+08   -43.424      2.679E+09    93.392    
REFL11       1.126E+13    -7.168      1.618E+11   135.296    
REFL33       2.658E+11   164.973      8.910E+09    -2.226    
REFL55       3.012E+11   -75.216      1.210E+10   172.764

SensMat_23May2013_withIQ_andCorrectPhases.png

  8648   Tue May 28 14:52:56 2013 JenneUpdateLSCPRMI sensing matrix: Got it!

Just so we have it, here is the re-analysis with the correct plot and phases for the May 21st data, taken near the violin mode:

Sensing Matrix, units = counts/meter, phase in degrees
 
            PRCL Mag   PRCL Phase    MICH Mag   MICH Phase  
AS55         9.048E+11   -22.880      2.927E+12   107.071    
REFL11       2.954E+16   -21.628      3.670E+14   123.857    
REFL33       2.757E+14  -192.608      9.186E+12    -4.037    
REFL55       2.868E+14   -82.690      1.186E+13   170.097 

SensMat_21May2013_withIQ_andCorrectPhases.png

Even though this data was taken near the violin mode (oops!), it is fairly consistent with the stuff taken a few days later at 580Hz (elog 8644). 

Neither of these is at all similar to what Kiwamu had measured a year ago (elog 6283), but we have changed many, many things since then.  He also includes an Optickle simulation, which is fairly similar to the Koji simulation in the wiki, but neither his measurements nor mine are particularly close to the simulated version.  I should think about why this is.

Also, I have fixed up the measurement scripts so that they record all of the relevant current settings / information:  Current actuator calibration, current PD demod phases, drive amplitude and drive frequency.  The "Analyze Saved Data" script has been updated to read all of this info from the files.  If you want to plot / look at any old data, open up SensMatAnalyzeSavedData in /scripts/LSC/SensingMatrix/ and put in the relevant filename that you want (which should be saved in /scripts/LSC/SensingMatrix/SensMatData/)

  8649   Tue May 28 17:00:50 2013 JenneUpdateASCProposed POP path, to be installed this evening

I have mounted 2 2" G&H high reflective mirrors, to be used in the new POP path.  Manasa and Annalisa are doing green things on their respective arms, so I will hopefully be able to install the new POP path after dinner tonight.

Here are photos of the current POP path, and my proposed POP layout.  In the proposed layout, the optical components whose labels are shaded are the ones which will change.

CurrentPOPpath.pdf

ProposedPOPpath.pdf

  8658   Thu May 30 17:18:58 2013 JenneUpdateASCNew POP path

I have placed the G&H mirrors and the Y1 as pictured in my proposed layout in elog 8649.  The distance between the 2" lens and the PDs has increased, so the focus point is all wrong.  I have measured the distances between optics on the table, and will pick new lenses and finish the POP layout later today or tomorrow.

For now, here are the powers measured using the Ophir power meter:

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

PRM-ITMY lock, POPDC was ~190 counts

5.29 uW after Y1 weird angle.  Can't see beam before then to measure

5.27 uW before BS50
3.5 uW before razor PD
3.00 uW before 110PD

 ------------------------

After installing G&H mirrors, replacing BS-98 with Y1:

4.94 uW before y1 (after G&H's)
4.92 uW after y1
2.66 uW before razor PD
1.61 uW before 110PD

  8663   Sat Jun 1 14:14:56 2013 JenneUpdateASCNew POP path

I have a lens solution for the new POP QPD, plotted below.  To get the beam size, I started with the waist at the ITM, so the out of vacuum table starts around 6 meters on this plot.  Also, "PD" is the QPD, but the position marked on the plot is the maximum distance from the 2nd lens.  In reality, I will place it a few cm after the lens.  Once I've got that laid out, I'll move the 110PD (and its lens) and the camera around so that they are in good spots relative to the beam size.

 POP_QPD_lensSolution.png

Here is a photo of the way I left the table last Thursday.  The notations in orange indicate what I need to do to make the actual table match my lens solution.

 POX_table_30May2013progress.pdf

 

  8697   Wed Jun 12 23:06:33 2013 JenneUpdateGreen LockingY arm locked with green but bad mode matching
Hmmm.  You seem to be saying that more light is reflected than is injected. Is this a units problem? Or was some IR on the power meter during the 'reflected' measurement? 
We should look at it with fresh eyes in the morning. 
  8700   Thu Jun 13 15:04:16 2013 JenneUpdateLSCNew modeled sensing matrix

Using all of the latest parameters that I can find, I have re-modeled the 40m sensing matrix.  Also, I have it output the data in a format that can be used by the same plotting function as the measured sensing matrix, so they are nice and easy to compare.

The newly modeled 40m sensing matrix:

SensMatModel_13June2013.png

To compare, here is the measured sensing matrix from elog 8644:

SensMatMeas_23May2013.png

Notice that (a) the units are different, so don't focus too much on the amplitudes of the lines, and (b) all of the measured and modeled matrix elements are pretty similar, except for the REFL11.  REFL11 (top right in model plot, top center in measured plot) looks like it's flipped, as well as rotated.  The new model doesn't match up too well with the Kiwamu/Koji models (which matched eachother okay), but I like that the new model matches the measurements fairly well.  The Koji sensing matrix: on the 40m wiki

EDIT: I have replaced the modelled plot with a new version.  The data and numbers are the same, but I have switched the labels on the individual radar plots, and forced them to be in the same order as they are in the measured plot.

  8705   Fri Jun 14 00:32:43 2013 JenneUpdateLSCNew modeled sensing matrix

I put in a new version of the modelled plot.  I figured out a different way to keep things generic so the same script can be used for other sites, but writes the names in the same format as the measured matrix, so the correct order is preserved.

The REFL11 measurement is consistent with the one in elog 8648 (data taken a few days earlier), within the error bars.  My goal for tonight is to hopefully get the POP path back in order, so that I can lock the PRMI again, and can measure again if I want.

The error bars for each sensor are only taken once (with no drive, so it's the noise in the "dark" sensor).  I take 6 "dark" measurements for each sensor, and get the stdev.  Then I use that and propagate it through for each measured sensing matrix element.  So, the PRCL and MICH error bars for REFL11 were created from the same standard deviation, and propagated in the same way, but the values plugged into the partial derivative of the function were different for PRCL and MICH. 

s_f = \sqrt{ \left(\frac{\partial f}{\partial {x} }\right)^2 s_x^2 + \left(\frac{\partial f}{\partial {y} }\right)^2 s_y^2 + \left(\frac{\partial f}{\partial {z} }\right)^2 s_z^2 + ...}(wikipedia - propagation of uncertainties)

 

Also, to answer an emailed question via the elog, the "0 degree" axis of the plots is the 0 demod phase axis, which corresponds to the I output of the demod boards (the I input to the RFPDs, before the phase rotation).  The "I" axis that I've drawn is the current demodulation phase that we have, which corresponds to the I_ERR output of the RFPDs after the phase rotation, which is the PD_I signal that goes into the LSC input matrix.  I draw this to help us see if our current demod phase is well tuned or not.

Yes, the MICH and PRCL signals are not at all orthogonal in the REFL33 sensor.  I think this is because our modulation frequency was chosen to be good in the case of the full DRFPMI IFO, not the corner IFO cavities.  As I calculated in elog 8538, the ideal frequency for the PRMI is 18kHz larger than our current modulation frequency. 

For the plots below, note that 11.066134 MHz is our current actual modulation frequency, and 11.0843 MHz is my calculated ideal modulation freq

Model, using our current modulation frequency, and the designed PRCL cavity length (same as elog earlier today):

SensMatModel_13June2013_currentPRMIfreq.png

Model, using the "ideal" PRMI modulation freq, and the PRCL cavity length used in elog 8538, where I calculated that number (a few cm different than the design PRCL length):

SensMatModel_13June2013_idealPRMIfreq.png

You can see that if we could use a better frequency, we would get much, much better signal separation.  Since our modulation frequency choice is related to our vacuum envelope constraints (we can't make the arms of a length that will have the sidebands exactly antiresonant when the arms are locked on the carrier), I hope that this will not be a significant issue in aLIGO. 

  8707   Fri Jun 14 03:10:40 2013 JenneUpdateASCNew POP path - PDs in place, need cabling

I have placed the lenses and the PDs in their new positions on the POP path.  As Koji had pointed out to me in reply to elog 8663, what really matters to get the beam size I want on the QPD is the distance between the lenses, and not so much the absolute position of the lenses (since the Rayleigh range of the POP beam coming out of the vacuum is so long), so I left the 2" lens in place, and made the distance between the Y1 and the QPD's lens 35 cm. 

I didn't move the camera very much, mostly just enough to get the beam centered on the TV.  I need to check where this is in terms of the beam shape, to see where I should move it to, so that I'm getting useful beam motion information by looking at the camera. 

The steering mirror for the POP110 PD is still between the camera and the steering mirror for the QPD, there's just much less space between those 3 elements than there was previously.  I put the POP110 PD's lens and the PD itself in such a way that the PD is at the focus.

The PD which used to be the ASC razor blade PD has been put back in the cabinet.  The cable that was plugged into it was being used for POPDC.  I will need to switch things back so that POPDC is once again coming from the POP110 PD.  Also, I need to bring over the power supply for the QPD, and lay some cables between the supply/readout box and the IOO chassis (where Jamie has freed up some channels for me).

Also, while I was on the POX table, I was reminded that we need to deal with the ITMX oplev situation, which Gautam detailed in elog 8684.  I will ask Steve to take care of it when he's back from vacation.

  8710   Fri Jun 14 17:54:11 2013 JenneUpdateASCNew POP path - cabling work

Quote:

... I need to ... lay some cables between the supply/readout box and the IOO chassis (where Jamie has freed up some channels for me).

 I have made 3 dongles that go from 2-pin lemo to BNC so that I can connect the 3 QPD signals (X, Y, Sum) to the IOO ADC (Pentek Generic board in 1Y2, which also has the MC channels). 

The interface board with the 2-pin lemo connectors doesn't have anything in the DCC for the document number (D020432), so I asked BAbbott, and he said: "After a bit of searching, I found that on psage 2 of D020006-A-pdf ( https://dcc.ligo.org/LIGO-D020006-x0 ), Pin 1 of each LEMO connector is the + leg, and pin 2 is the - leg.  This means that you should connect the center conductor of the BNC (if you don't have any 2-wire twisted-pair cables around) should be connected to pin 1 of the LEMO, and the outer conductor should be connected to Pin 2.  According to http://il.rsdelivers.com/product/lemo/epg0b302hln/2-way-size-0b-pcb-mount-socket-10a/1305621.aspx Pin one is the top one on the right-angled LEMO."  According to page 50 of the lemo data sheet, pin1 is the one with the mark next to it, when you are looking at the solderable end.


  8711   Mon Jun 17 16:34:15 2013 JenneUpdateLSCSensing Matrix vs. Schnupp Asymmetry

I have made some plots of the sensing matrix (PRCL / MICH amplitude ratio, and relative angle) versus Schnupp asymmetry for all the configurations that involve the power recycling cavity.  I am still meditating on what they mean for us, in terms of whether or not we should be changing our Schnupp asymmetry.

The Schnupp asymmetry scan starts at 1mm, rather than 0.  Also, recall that our current Schnupp asymmetry is 3.9cm.

PRMI:

SchnuppLoop_PRMI_REFLdiodes_zoom.png

SchnuppLoop_PRMI_REFLdiodes_phase.png

DRMI:

SchnuppLoop_DRMI_REFLdiodes_zoom.png

SchnuppLoop_DRMI_REFLdiodes_phase.png

PRFPMI:

SchnuppLoop_PRFPMI_REFLdiodes.png

SchnuppLoop_PRFPMI_REFLdiodes_zoom.png

SchnuppLoop_PRFPMI_REFLdiodes_phase.png

DRFPMI:

SchnuppLoop_DRFPMI_REFLdiodes.png

SchnuppLoop_DRFPMI_REFLdiodes_zoom.png

SchnuppLoop_DRFPMI_REFLdiodes_phase.png

  8712   Mon Jun 17 17:51:43 2013 JenneUpdateLSCPOP QPD cables laid

Power not on to the POP QPD yet though.  Also, still need to reconnect POPDC.

  8713   Mon Jun 17 21:10:25 2013 JenneUpdateLSCSensing Matrix vs. Schnupp Asymmetry

The plots, with a log y axis

PRMI:

SchnuppLoop_PRMI_REFLdiodes.png

DRMI:

SchnuppLoop_DRMI_REFLdiodes.png

PRFPMI:

SchnuppLoop_PRFPMI_REFLdiodes.png

DRFPMI:

SchnuppLoop_DRFPMI_REFLdiodes.png

  8719   Wed Jun 19 00:46:06 2013 JenneUpdateSUSsave/restore alignment scripts now also work for TTs, fixed a bug

I have done a quick update of the IFO_ALIGN screen's save and restore scripts, so that we can now also save, restore, and view the saved values for the input tip tilts. 

In the past, there was an "if" statement to check if the optic was a PZT, and if so, define the alignment channels accordingly (since all the SOS suspensions have the same format for the name, and the PZTs were the odd ones out).  I have removed the mention of PZTs, and replaced the if statement with an "if TTs" statement, and put in the correct channel names (C1:IOO-TT#_PIT_OFFSET, and the same for YAW). 

Also, I caught a bug in the code, which explains some confusing behavior that I had seen in the past.  When deciding if the restore script should take small steps or just do a big step, it looked at the difference between the saved value and the current value of the slider.  It was *not* looking at the absolute value of the difference.  So, if you had misaligned a slider by hand, and it was in the opposite direction of what the misalign script does, the restore script wouldn't realize that the optic needed to be restored in small steps.  I have now fixed this bug for both pit and yaw cases of the restore script.

  8720   Wed Jun 19 01:12:42 2013 JenneUpdateASCmodel name ASS -> ASC ???

I am proposing a model name change.  Currently, we have an "ASS" model, but we do not have an "ASC" model. 

The ASS is currently using ~17 of 60 available microseconds per cycle.  So, we have some cpu overhead available to put more stuff on that cpu. Like, say, ASC stuff.

So, my proposal is that we change the ASS model name to "ASC", and put all of the ASS-y things in a top_names block, so we retain the current channel names.  The IOO top_names block that is in the current ASS model (which is there to send signals to the LSC DAC for the input tip tilts, even though the names need to be IOO) should obviously stay on the top level, so that things in there retain their names.

Then, I can make a new top_names sub-block for ASC-like things, such as the new POP QPD. 

Inside the ASC block (in the ASC model), I'm currently thinking something simple will do..... QPD inputs, going to a matrix, which outputs to the filter banks in the "length" degree of freedom basis (PRCL, SRCL, etc), then another matrix, going to the ASC suspension paths. 

So, for example, the POP QPD pitch would go to the PRCL_PIT filter bank, and then on to the PRM_ASCPIT path in the SUS screen.

Or, in another example case, IPPOS yaw would go to an input pointing filter bank, then on to TT1's yaw slider.

EDIT:  After a few minutes of thinking, I think I also want triggering, and perhaps filter bank triggering, in the ASC model.  One of the reasons Koji has been pushing for the new automation system is that when the PRC fell out of lock, the ASC path would kick the PRM until Koji ran a down script.  Triggering will fix this issue, and it's the kind of thing that needs to happen quickly, so may not really be appropriate for the Guardian anyway.

  8722   Wed Jun 19 02:46:19 2013 JenneUpdateCDSConnected ADC channels from IOO model to ASS model

Following Jamie's table in elog 8654, I have connected up the channels 0, 1 and 2 from ADC0 on the IOO computer to rfm send blocks, which send the signals over to the rfm model, and then I use dolphin send blocks to get over to the ass model on the lsc machine. 

I'm using the 1st 3 channels on the Pentek Generic interface board, which is why I'm using channels 0,1,2. 

I compiled all 3 models (ioo, rfm, ass), and restarted them.  I also restarted the daqd on the fb, since I put in a temporary set of filter banks in the ass model, to use as sinks for the signal (since I haven't done anything else to the ASS model yet).

All 3 models were checked in to the svn.

  8727   Wed Jun 19 18:24:14 2013 JenneUpdateCDSProto-ASC implemented in ASS model

I have implemented a proto-ASC in the ASS model.  

In an ASC block within the ASS model, I take in the POP QPD yaw, pit, and sum signals.  I ground the sum, since I don't have normalization yet (also, the QPD that we're using normalizes in the readout box already).  The pit and yaw signals each go through a filter bank, and then leave the sub-block so I can send the signals over to the SUS model, to push on PRM ASCPIT and ASCYAW. 

In doing this, I have removed the temporary PRM ASCYAW connection that Koji had made from the secret 11'th row of the LSC output matrix (see Koji's elog 8562 for details from when he implemented this stuff).

LSC, SUS and ASS were recompiled, and restarted.  I also restarted the daqd on the fb.

  8728   Wed Jun 19 22:02:03 2013 JenneUpdateASCNew POP path - ready to try

I put the POPDC cable back to the DC output of the bias tee that is the first thing at the LSC rack that the POP110 PD sees.  So, now we should be back to the old nominal PRCL locking, with the addition of the new QPD.

I'm going to give it a whirl.....

  8729   Wed Jun 19 22:38:15 2013 JenneUpdateComputer Scripts / ProgramsLSC normalization sqrt_mon channels added to conlog

 

 Something has happened that all of the C1:LSC-dof_NORM_SQRT_ENABLEs are disabled, but normally some are enabled and others are not.

In the hopes that miraculously this change happened after Jamie restarted the conlog this afternoon, I checked the conlog.  These channels, however, were not recorded. 

Using the instructions on the conlog wiki page, I added the _MON channels to the conlog list.  The one snag I hit was that the medm screen referred to in the wiki isn't usable if you open it by hand using the medm gui, since it needs to know what IFO you're at to fill in the macro expansion variables.  To remedy this, I changed the "FE STATUS" button on the sitemap to "CDS", and added the conlog screen to the list of options.  

Now I see that the conlog at least knows about these channels, for future reference.

  8730   Wed Jun 19 23:50:44 2013 JenneUpdateLSCPRCL locking again

This is a mid-evening update, so I don't forget all the stuff I've already done.

Aligned PRMI, no nice flashes on POP110.  Aligned and locked PRM-ITMY half-cavity on the carrier, and used that POP beam to center the beam on the POP110 PD.  I also turned on the new QPD and centered the beam on it.

Notes about QPD setup:  The "zero/cal" switch is OFF, so none of the small knobs on the front (basically, everything but the gain knob) should be bypassed.  The gain knob is set to position 3.  This is the highest gain that I can have without the "too much light" saturation light blinking on the front panel.  (During this time, POP110I is flashing around 200 counts).

I made a super hacky ASC screen, which is accessible from the ASC button on the sitemap.  While there is a pitch path in the model, I only put in the yaw elements (except for the QPD readouts) in the screen, since that's what I'll be using for now. 

I added filter banks to the front side of the ASC subblock in the ASS model, so that I have a place to monitor the QPD signals on the screen and with striptool. 

Using the settings that Koji recorded in elog 8521 in the "Locking with SQRT(POP110I)" section (and no ASC engaged so far), I can lock the PRMI for ~10 or 20 seconds, at 150 or 200 counts on POP110I.  So, I'm doing well so far, and next up is to copy the ASC filters Koji made in elog 8562, and try the new ASC.

  8731   Thu Jun 20 01:13:18 2013 JenneUpdateLSCPRCL locking again - no ASC success

I didn't have any success with the ASC tonight.  I copied over the filters that Koji had used in elog 8562, and put them in the new ASC filter banks (and turned them off in the SUS-PRM_ASCYAW bank).  I also moved all the old scripts that were in .../scripts/ASC to an OLD subdirectory (the most recent edit is from 2009 sometime).  I then copied over the up and down scripts that Koji had written for his ASC test into the ..../scripts/ASC directory, and modified them to work with my new channels. 

I then tried locking, and wasn't very successful.  Actually, my best lock, ~4 minutes, including tweaking up the PRM alignment, was when the ASC path was off (even though I thought it was on).  After discovering my mistake, I tried locking for another hour or so, but haven't really gotten anywhere.  The lock stretches I'm getting are rarely long enough for me to get to the terminal and run my up script, and the maybe ~6 or 7 times I've been able to run it, I haven't converged toward finding a good gain value for the PRC yaw loop.  At some point, I redid the MICH alignment since it had drifted away a bit, but that didn't really help.

I think that one of the next things I might try is carrier-locking the PRMI, to find okay loop gain settings for the ASC path.  Since the QPD output is already normalized (I'd have to custom-make some electronics to make it non-normalized), I think the gain should be the same for both carrier and sideband lock cases.

_______________________________

Once I finally get a good, stable, PRMI sideband lock, I think I need to take the following measurements:

* CTRL and ERR spectra for MICH and PRCL

* TFs for MICH and PRCL loops

* Sensing matrix, including AS55, REFL11, REFL33, REFL55, POX and POY.

---->> Are there any others?

  8737   Mon Jun 24 11:51:23 2013 JenneUpdateLSCNew modeled sensing matrix

Quote:

 This is nice - how about figuring out how to plot the measurement and model on the same plot? I guess we need to figure out how to go from counts to Watts.

I haven't done a units conversion for the measured vs. modelled plot,  but at least we can compare the separation between the different degree of freedom signals.  Figuring out why the REFL11 measurement and models are so different is still high on my to-do list.  But at least the measurements that were taken last month are consistent with one another. EDIT:  The separation angles match up pretty well between the 2 sets of measurements, but the overall rotation isn't really consistent.  I do not believe that the phase rotation values that we're using online changed between the measurements, so the I&Q lines should be the same for both seets of measurements....however, I did not write down the phase rotation values at the time of the first measurement, so there's a chance that they were different.  Also, something that I need to monitor is the coherence of my measurement, to make sure I'm really driving and measuring something.

 

2 measurements, with overall rotation arbitrarily rotated to make MICH lines match up:

SensMatMeas_23May2013_21May2013_overlay.png

Same 2 measurements, without the arbitrary overall rotation:

SensMatMeas_23May2013_21May2013_NoRotation_overlay.png

Measurement vs. Model, with the *modelled* phase arbitrarily rotated:

SensMatMeas_23May2013meas_13June2013model_overlay.png

  8739   Mon Jun 24 16:41:40 2013 JenneUpdateCDSProto-ASC implemented in ASS model

I am working on making the Proto-ASC less "proto".  I have put IPC senders in the LSC model to send the cavity trigger signals over to the ASS model, for ASC use.  I'm partially done working on the ASC end of things to implement triggering.

LSC should be compile-able right now, ASS is definitely not.  But, I expect that no one should need to compile either before I get back in a few hours.  If you do - call me and we'll figure out a plan.

  8740   Tue Jun 25 00:13:00 2013 JenneUpdateCDSProto-ASC implemented in ASS model

I have finished my work on the LSC and ASS models for now. The triggering is all implemented, and should be ready to go.  There are no screens yet.

I have *not* compiled either the LSC or the ASS, since Rana and Manasa still have the IFO.

  8753   Wed Jun 26 04:38:02 2013 JenneUpdateLSCPRCL locking again - ASC success

With Rana's help/supervision/suggestions, I have closed the loop on the PRMI ASC servo with the new QPD.  I think I've had it locked for ~30+ minutes now.  It was locked for ~45 minutes, but then the MC momentarily lost lock.  I immediately recovered the PRMI+ASC (after small PRM yaw tweaking, since the ASC isn't triggered yet, so the MC lockloss caused a big yaw step function to go to the PRM, which displayed a bit of hysteresis.).

My biggest problem was that I didn't really understand Koji's servo filter choices, so I wasn't using the right ones / doing good things.  In particular, I need to compensate for the oplev servo filters.  The oplev servo shape is something like ^, so the 1/(1+G) shape is something like =v= (ignoring the lower horizontal lines there).  For tonight, we just turned off the PRM oplevs, but clearly this isn't a permanent solution.  (Although, after Rana went in and roughly centered the PRM oplev, we noticed that turning the oplev on and off doesn't make a huge difference for the PRM....we should investigate why not.  Also, we turned off the FM2 3.2Hz resonant gains in the PRM oplevs, since the Q of those filters is too high, much higher than our actual stacks). 

Rana and I also locked the PRM-ITMY half cavity, and used that beam to realign the beam onto the POP QPD, POP110 PD, and the camera. 

The POP QPD pitch and yaw signals with the half cavity have some noise, that looks like 60Hz crap.  Since this goes away (rather, is much less noticeable) with the regular sideband-locked PRMI, we suspect this is a problem with perhaps the normalization, with the sum very low, and having some noise on it.

Once we had our ASC filters set up (not the 10Hz boost yet though, I think), if I increased the gain from -0.02 to -0.03, we start to get some gain peaking.  With a gain of -0.04, the peak is very noticeable around 250Hz.  We aren't sure where this is coming from, since it shouldn't be coming from the ASC loop.  The UGF of that loop is much lower (I measured it, to check, and the UGF is ~5Hz). Anyhow, this is still a mystery, although the gain of -0.02 holds the cavity pretty well.

I measured the power spectra of the POP QPD pit, yaw, sum, as well as POPDC and POP110I, with the ASC loop on and off (dashed lines are with the loop on.  You can see that the yaw motion as seen on the QPD was reduced by almost 2 orders of magnitude below 1Hz.  It also looks like we can win some more by turning on the equivalent pitch ASC servo (this is also something we see when looking at the dataviewer traces).

I also tried to measure the PRMI sensing matrix, but I get some weird results, even after I double the drive actuation.  I need to be checking whether or not my drive is actually coherent with the error signals that I'm seeing, because right now I'm not sure that I believe things. I'm going to leave that on the to-do list for tomorrow night though.

Next up:

* Engage POP QPD -> pitch loop, copying yaw loop.

* enable ASC triggering

* model PRMI sensing matrix and error signals, bringing one arm into resonance

* Lock the PRMI, and bring the Xarm into IR resonance using the ALS system.

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

Here are some numbers and plots from the night:

Right now, I'm locking the LSC with:

MICH LSC with AS55Q, FMs 4 and 5 on, FM 3 is triggered, gain = -40.0, normalized by sqrt(POP110I)*0.1

PRCL LSC with REFL33I, FMs 4 and 5 on, FM 9 is triggered, gain = +2.5, normalized by sqrt(POP110I)*10

(FM3 of MICH and FM9 of PRCL are the same, just in different spots).

The ASC (only POP yaw -> PRM yaw right now) has:

FMs 1,2,5,6 on (1 = integrator [0:0.1], 2 = 3.2 res gain, 5 = [1000,1000:1 and gain of 0.01], 6 = 10Hz boost).  Gain = -0.020,  Limit=5000.

Turn off the input, turn on the output and the gain, clear the histories (to clear out the integrator in FM1), then turn on the input.

PRM oplev is OFF. (need to put in a filter to compensate for it in the ASC servo, but for tonight, we just turned it off.)

We measured the spectra of the POP QPD signals with the ASC loop on and off:

PRMI_ASC_yawOnly_powerSpectra_25June2013.pdf

I also measured the ASC loop (with the PRM oplev still off):

 PRMI_ASC_yawOnly_25June2013_mag.pdf

PRMI_ASC_yawOnly_25June2013_phase.pdf

PRMI_ASC_yawOnly_25June2013_coherence.pdf

(sorry about the separate plots - I can't make DTT give me more than 2 plots on a page at a time right now, so I'm giving up, and just making 3 separate pages)

Weird sensing matrix, unsure if I'm really getting good coherence:

SensMatMeas_26June2013.png

  8756   Wed Jun 26 13:37:13 2013 JenneUpdateIOOMC very misaligned - put back

Not sure why it was so poorly aligned, since the misalignment "event" happened while we were all away at lunch, but I steered the MC optics until their SUSYAW and SUSPIT values were about the same as they were before they got misaligned.  MC autolocker took over, and things are back to normal.

  8764   Thu Jun 27 15:50:03 2013 JenneUpdatePEMBLRMS are going crazy

The BLRMS are totally crazy today!  I'm not sure what the story is, since it's been this way all day (so it's not an earthquake, because things eventually settle down after EQs).  It doesn't seem like anything is up with the seismometer, since the regular raw seismic time series and spectrum don't look particularly different from normal.  I'm not sure what's going on, but it's only in the mid-frequency BLRMS (30mHz to 1Hz).

Here are some 2 day plots:

 

WeirdBLRMSincrease_27June2013_rawSeis.png

WeirdBLRMSincrease_27June2013_Gur1xBLRMS.png

WeirdBLRMSincrease_27June2013_lowFreqBLRMS.png

  8766   Thu Jun 27 17:04:49 2013 JenneUpdatesafetyNitrogen bottle too hot - overpressured

All of us in the control room / desk area heard a sudden whoosh of air a few minutes ago.  It kind of sounded like a pressure washer or something.  We determined that the northmost nitrogen bottle outside the front door was letting out all its gas. 

It's a gazillion degrees outside (okay, only 91F, according to a google of "Caltech Weather"), and those bottles are in direct sun all day.

We are leaving the bottle as-is, since it seems like its has finished, and nothing else is happening.

  8767   Thu Jun 27 17:09:41 2013 JenneUpdateLSCPRCL locking again - POP PIT work

Last night before dinner, I copied over the ASC yaw servo filters to the ASC pitch filter bank.  Using ASC gain of +0.001, I was getting the ~250Hz oscillations that Rana and I had seen with yaw. 

Rana pointed out to me that my measured TF of the yaw loop doesn't look right up in the several hundred Hz region:

MeasuredVsModeledASCyaw.png

As you can see on the right side, which is all of the PRCL ASC yaw filter banks, multiplied by a simulated pendulum filter, the magnitude should just keep decreasing.  However, on the measured plot on the left, you can see that I have a little gain hump.  I'm not sure what this is from yet.

  8780   Fri Jun 28 02:12:41 2013 JenneUpdateLSCPRCL locking again - ASC work

Rana had the epiphany that I didn't have any antiwhitening for my POP QPD.  Ooops. 

We looked at the schematic for the Pentek Generic board (pdf), and saw that it has a Zero @ 15Hz, and Poles @ 150Hz and 1500Hz, times 2 stages.  We determined from the TF that I posted that probably both stages are engaged, so I made an antiwhitening filter consisting of the inverse (so, 2 poles at 15Hz, 2 zeros at 150Hz and 2 zeros at 1500Hz).  [Rana points out that for this low frequency system we may not want to include the 1500Hz compensation, since it is probably just enhancing ADC noise].  The ASC system worked really well, really easily, after that.

Another note though, the AA stage of the Pentek Generic boards have 4 poles at 800Hz, which are not compensated.

Rana also added a 60Hz comb to the filter bank with the AntiWhitening, since the QPD has an unfortunately large amount of 60Hz noise.  Also, the 60Hz lowpass in the ASC loop was engaged for both pitch and yaw.

Rana, Lisa and Manasa also found that the ASC system was *more* stable with the PRM oplev ON. 

So, the ASC locking situation is:

PRM oplev loops on.

AS-POP_QPD_[PIT/YAW] filter banks with FM1, FM6 on.

ASC-PRCL_[PIT/YAW] filter banks with FM1, FM5, FM6 and FM9 on.

ASC-PRCL_YAW_GAIN = -0.040

ASC-PRCL_PIT_GAIN = +0.030

(No triggering yet).

The ASC Up and Down scripts (which are called from the buttons on the ASC screen) have all of these gain settings, although they assume for now that all the filters are already on.

Here's a screenshot of the power spectra showing the angular motion suppression. The PDF is attached so you can zoom in and see some details.  The dashed lines are the "PRMI locked, ASC off" case, and the solid lines are the "PRMI locked, ASC on" case.  You can see that according to the QPD, we do an excellent job suppressing both the pitch and yaw motion (although better for yaw), but there isn't a huge effect on POPDC or POP110I.  While we could probably do better if we had a 2 QPD system with the QPDs at differet gouy phases, this seems to be good enough that we can keep the PRMI locked ~indefinitely. 

 Screenshot-Untitled_Window.png

I would like to compile the ASC model, so that I can implement triggering.  For tonight, we did not have the ASC engaged during our PRMI+Xarm tests (see Manasa's elog), but I think it'll make things a little easier if we can get the ASC going automatically.

  8781   Fri Jun 28 02:23:00 2013 JenneUpdateLSCNeed to measure sensing matrix at REFL165

[Lisa, Rana, Jenne]

Lisa asked to see a model of the PRMI sensing matrix with REFL165 included, in the hopes that it wouldn't be as degenerate as REFL33.

SensMatModel_28June2013_InclREFL165.png

The conclusion, immediately after looking at this, is that I should make sure the REFL beam is nicely aligned onto the REFL165 PD (Koji did some tests, swapping out the REFL165 resonant PD with a broadband PD, and I don't remember if he aligned beam back onto the REFL165 PD).  Then, I need to measure the PRMI sensing matrix, including REFL165.  Hopefully, it is similar to the model, and we can use it as our 3f diode for locking.

  8788   Mon Jul 1 23:27:07 2013 JenneUpdateLSCSensing Matrix vs. Xarm sweep

I have modeled the PRMI sensing matrix as I bring the Xarm into resonance.  In optickle, I have the PRMI on sideband resonance, the ETMY is artificially set to have a transmission of 1, and the ETMX has it's nominal transmission of 15ppm.  I start with the ETMX's microscopic position set to lambda/4 (antiresonant for IR in the arm), and take several steps until the ETMX's microscopic position is 0 (resonant for IR in the arm).

Xarm antiresonant:

Modeled sensing matrix, units = W/m, Offset = 2.66e-07, phase in degrees
 
            MICH Mag   MICH Phase    PRCL Mag   PRCL Phase  
AS55         3.348E+04   142.248      5.111E+03    70.571    
POX11        3.968E+01   -66.492      1.215E+04    54.312    
REFL11       3.231E+05    24.309      9.829E+07   144.311    
REFL165      9.946E+03  -159.540      4.540E+05   -64.710    
REFL33       1.963E+04  -168.530      1.573E+06    -2.744    
REFL55       1.160E+06    -6.755      5.429E+07    86.895 

 

Xarm resonant:

Modeled sensing matrix, units = W/m, Offset = 0, phase in degrees
 
            MICH Mag   MICH Phase    PRCL Mag   PRCL Phase  
AS55         1.647E+06    57.353      3.676E+06   -81.916    
POX11        3.927E+02  -118.791      2.578E+04  -102.158    
REFL11       7.035E+05    61.203      1.039E+08   167.149    
REFL165      1.602E+04  -144.586      5.971E+05   -49.802    
REFL33       2.157E+04   171.658      1.940E+06    -9.133    
REFL55       1.822E+06     7.762      6.900E+07   101.906 

 

For REFL55, the MICH magnitude increases by a factor of 1.6, while the PRCL  magnitude increases by 1.3 .  The MICH phase changes by 15 degrees, while the PRCL phase also changes by 15 degrees.  Just eye-balling (rather than calculating), the other REFL PDs look to have similar-ish magnitude and phase changes.  Certainly none of them are different by orders of magnitude.

Movies forthcoming.

  8790   Tue Jul 2 02:29:47 2013 JenneUpdateLSCSensing Matrix vs. Xarm sweep

Here is the Sensing Matrix movie (sorry for the iffy quality - my movies usually come out better than this):

 

This is the sensing matrix for the sideband locked on PRMI, bringing the Xarm into resonance from anti-resonance, in 20 equally-spaced steps.  You can see the microscopic ETMX offset (units of meters) in the title of the figures.

I was surprised to see some of the 'jumps' in the sensing matrix that happen near the end, when the arm is almost in resonance.  I'm in the process of making movies of the error signals as the Xarm is brought into resonance.  I'll have to post those in the morning, since they're taking a long time to produce and save, however when I looked at a few, there is some weird stuff going on as we get close to resonance, even with the 3f signals. 

The modeling phone call is in the morning, but if anyone who is not regularly on the call has thoughts, I'm all ears.

  8805   Mon Jul 8 15:31:48 2013 JenneUpdateASCPOP QPD calibration prep

I am prepping to do the POP QPD calibration, and so have turned off the POP QPD, and put it onto a micrometer stage.  My plan is to (after fixing the ASC servo filters to make the servo AC coupled, rather than DC coupled) lock the PRM-ITMY half cavity, and use that beam to calibrate the QPD.  While this isn't as great as the full PRMI, the PRMI beam moves too much to be useful, unless the ASC servo is engaged.

While on the table, I noticed 2 things:

* In order to place the micrometer, I had to temporarily move the POP55 RFPD (which has not been used in quite a long time).  I think it's just that the panel-mount SMA connector isn't tight to the panel inside, but the RF out SMA cable connector is very loose.  I have moved the POP55 RFPD to the very very south end of the SP table, until someone has time to have a quick look. (I don't want to get too distracted from my current mission, since we haven't put beam onto that PD for at least a year).

* The ITMX oplev beam setup isn't so great.  The last steering mirror before the beam is launched into the vacuum is close to clipping (in yaw... pitch is totally fine), and the steering mirror outside of vacuum to put the beam on the QPD is totally clipping.  The beam is falling off the bottom of this last steering mirror.  Assuming the beam height is okay on all of the input optics and the in-vac table, we need to lower the last steering mirror before the oplev QPD.  My current hypothesis is that by switching which in-vac steering mirror we are using (see Gautam's elog 8758) the new setup has the beam pointing downward a bit.  If the problem is one of the in-vac mirrors, we can't do anything about it until the vent, so for now we can just lower the out of vac mirror.  We should put it back to normal height and fix the oplev setup when we're at atmosphere.

  8810   Tue Jul 9 11:41:22 2013 JenneUpdateASCPOP QPD calibration attempt

I was bad, and forgot to elog the most important part of my work yesterday - that I had rotated the POP QPD by 90 degrees, so that I could fit the micrometer onto the table.  There is a sticker on the front of the QPD to indicate which direction is "X" and "Y" for the output of the readout box.  Right now (and the way that I will mount the QPD to the table, after I redo the calibration today), X is PITCH, and Y is YAW.  Koji and Nic swapped the cables to the ADC to make this all consistent.

Yesterday, I locked the PRM-ITMY half cavity, and tried to take calibration data.  However, with no ASC servo engaged, the beam was still moving.  Also, with only the half-cavity, I had very little light on the QPD, and since it has internal normalization, the outputs can get a little funny if there isn't enough light.  I had checked, and even with the gain cranked up to maximum, the "light level too low" LED was illuminated.  So, my calibration data from yesterday isn't really useful.

Today, hopefully after lunch, I will lock the PRMI with the new AC-coupled ASC servo, so that I can have the servo on, and the PRMI locked on the sideband, so that I have more light on the QPD. 

After that, it seems that the final thing we need to do before we vent is hold an arm near, but off resonance, lock the PRMI, and then swing the arm in and out of resonance a bit.

  8812   Tue Jul 9 16:08:32 2013 JenneUpdateASCPOP QPD calibration attempt

[Jenne, Alex] 

Calibration data for the POP QPD has been taken, with the PRMI locked on sideband (with AS55Q and REFL33I, since it stayed locked longer with those 2).  ASC was on, AC coupled. 

We didn't get too far on either side of center of the QPD, since the ASC servo would go unstable, so we only explored the roughly linear region.  Data / plots / analysis to follow.

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