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ID Date Authorup Type Category Subject
  9753   Wed Mar 26 14:54:32 2014 KojiSummaryLSCPRMIsb locked with REFL165I&Q again

[Manasa, Eric, Koji]

PRMIsb was locked with REFL165I&Q.


- Aligned the arms with ASS. The misaligned ETMX and ETMY

- Configured PRMIsb with IFO_Configure screen

- Immediately PRMIsb was locked with REFL55I&Q

- Checked the REFL165 phase in terms of the REFL165Q vs PRCL. It was already well adjusted at -82.5deg. We tuned the phase a bit more and got -83.5deg.

- With DTT, relative gain between REFL55I and REFL165I was measured. REFL165I is about x10 higher than REFL55I and has the same sign.

- The transition of PRCL with the input matrix was just easy.

- With DTT, relative gain between REFL55Q and REFL165Q was measured. REFL165Q is about x3 higher than REFL55Q and has the same sign.

- The transition of MICH was flakey, but after careful adjustment of the PRM alignment, ~10s lock was achieved. It seemed that the PRM alignment fluctuation
  was bug enough to unlock the interferometer.

- Eric went into the lab and aligned all of the oplevs except for the SRM's one.

- Now the lock with REFL55 and also with REFL165 became more robust. Less MICH offset and darker AS port.


Input ports:
REFL55   WHTN: 45dB demod phase +45.0deg
REFL165 WHTN: 45dB demod phase -83.5deg

Input matrix: for acquisition:
REFL55I x 1.0 -> PRCL
REFL55Q x 1.0 -> MICH

Input matrix: PRCL Transition:
REFL55I x 1.0 + REFL165I x 0.0 -> x0.5 + x0.0 -> x0.5 + x0.05 -> x0.3 + x0.05 -> x0.2 + x0.05 -> x0.1 + x0.05 -> x0.0 + x0.05

Input matrix: MICH Transition:
REFL55Q x 1.0 + REFL165Q x 0.0 -> x0.5 + x0.0 -> x0.5 + x0.3 -> x0.3 + x0.3 -> x0.2 + x0.3 -> x0.1 + x0.3 -> x0.0 + x0.3

Triggers:
MICH POP110I 100up/10down / FM Trig FM2/3/9 35up 2down 5sec delay
PRCL POP110I 100up/10down / FM Trig FM2/3/6/9 35up 2down 0.5sec delay

Servo:
MICH OFS 0 / Gain 1.3 / Limitter ON
PRCL OFS 0 / Gain -0.04 / Limitter ON

Output matrix:
MICH PRM -0.2625 / BS 0.5
PRCL PRM 1.0

  9758   Fri Mar 28 17:22:55 2014 KojiSummaryLSCPRMIsb locked with REFL165I&Q again

While I'm looking at the PRM ASC servo model, I tried to use the current servo filters for the ASC
as Manasa aligned the POP PDs and QPD yesterday. (BTW, I don't find any elog about it)

I found no issue for locking PRMIsb with the REFL165I&Q signals if the PRM ASC is employed.
See this entry for the IFO settings.

It is just stable. The IFO is ready for the arm scanning.

=== ASC setting ===

PRCL_PITCH: FM1/3/9 x-0.004
PRCL_YAW: FM1/3/9 x-0.001

The PRM OPLEV has to be off when the PRM ASC is engaged. Actually, it turned out that we don't need OPLEV for locking.

  9761   Fri Mar 28 23:28:13 2014 KojiConfigurationGeneralNTP setting on nodus

[Koji Rana]

We are looking at NTP settings. I looked at nodus.

- xntpd is running

- We decided to start over the configuration file /etc/inet/ntp.conf

    - The old configuration was moved to ntp.conf.bak

    - The server configuration file was copied from ntp.server to ntp.conf

    - Caltech NTP servers 131.215.239.14 and 131.215.220.22 were selected as the servers we are reffering

    - Commented out the lines for "fudge" and "broadcast"

- xntpd was restarted

    - sudo /etc/init.d/xntpd stop
    - sudo /etc/init.d/xntpd start

- check how the daemon is running
      tail -50 /var/adm/messages

   Mar 28 23:00:49 nodus xntpd[27800]: [ID 702911 daemon.notice] xntpd 3-5.93e Mon Sep 20 15:47:11 PDT 1999 (1)
   Mar 28 23:00:49 nodus xntpd[27800]: [ID 301315 daemon.notice] tickadj = 5, tick = 10000, tvu_maxslew = 495, est. hz = 100
   Mar 28 23:00:49 nodus xntpd[27800]: [ID 798731 daemon.notice] using kernel phase-lock loop 0041
   Mar 28 23:00:49 nodus last message repeated 1 time
   Mar 28 23:00:49 nodus xntpd[27800]: [ID 132455 daemon.error] trusted key 0 unlikely
   Mar 28 23:00:49 nodus xntpd[27800]: [ID 581490 daemon.error] 0 makes a poor request keyid

- check the syncing staus by ntpq -p

        remote           refid      st t when poll reach   delay   offset    disp
   ==============================================================================
   *ntp-02.caltech. .CDMA.           1 u   37   64  377     0.56    3.010    0.08
   +ntp-03.caltech. ntp1.symmetrico  2 u   36   64  377     0.52    2.727    0.12

      this * means nodus is synced to ntp-02. "+" means it is stand by as a valid secondary server.  "when" increases every second.
      When "when" reaches "poll" the clock is synced to the server. These marks are not set at the beginning.
      It was necessary to wait for sometime to get synced to the server.

- Once nodus became a synced server, the realtime systems starts syncing to nodus automatically.

   controls@c1sus ~ 0$ cat /var/log/ntpd
   25 Mar 01:41:00 ntpd[4443]: logging to file /var/log/ntpd
   (...)
   28 Mar 23:13:46 ntpd[4983]: synchronized to 192.168.113.200, stratum 2
   28 Mar 23:14:25 ntpd[4983]: time reset +39.298455 s
   28 Mar 23:14:25 ntpd[4983]: kernel time sync status change 2001
   28 Mar 23:25:19 ntpd[4983]: synchronized to 192.168.113.200, stratum 2
   controls@c1sus ~ 0$ ntpq -p
        remote           refid      st t when poll reach   delay   offset  jitter
   ==============================================================================
   *nodus.martian   131.215.239.14   2 u   42   64  377    0.140   42.222  11.373

  9762   Sat Mar 29 00:11:39 2014 KojiConfigurationGeneralNTP setting on nodus

FB: /etc/ntp.conf was updated as below such that it refers nodus and also caltech server when nodus is not available

server 192.168.113.200
server 131.215.239.14

ntpd was restarted and

diskless RT machines: they are booted from /diskless/root on fb.
Therefore /diskless/root/etc/ntp.conf was updated in the same way as above.
When the machines are rebooted, this setting will be active.

control machines:

now they are referring nodus and other external servers too.

  9769   Mon Mar 31 23:57:22 2014 KojiSummaryASCPRM ASC characterization / design

A series of measurements / calculations for the PRM ASC characterization and servo design

1) Actuator characterization

The actuator responses of the PRM in pitch and yaw were measured (attachment figure 1). I believed the calibration of the oplev QPD to be
1 count/urad. The oplev servo loops were turned off at the FM inputs, and the filter banks were turned off so that the response has the open
loop transfer function except for the servo filter.

The measured transfer functions were fitted with LISO. The LISO results (c.f. the source codes) were shown in the figure. The responses also
include the 60Hz comb filter present in the input filters. The responses are well approximated by the single pendulum with f0 of 0.6-0.8 and q of 3.5 and 6.3.

From this measurement, the actuator responses of the PRM at DC are estimated to be 2.2 urad/cnt and 1.8 urad/cnt in pitch and yaw, respectively.

2) Sensor response of the POP QPD

As we already know how the actuators respond, the QPD optical gain can be characterized by measuring the actuator response of the QPD
(attachment figure 2). The QPD signals are such noisy that the response above 1Hz can't be measured with sufficient coherence. Below 1Hz,
the response is well represented by the actuator response measured with the oplev. From this measurement, the optical gains of the QPD
with respect to the PRM motion are 650 cnt/urad and 350 cnt/urad.

3) Open loop transfer function of the current ASC servo

By combining the above information with the servo setting of the servo filters, the open loop transfer functions of the PRM QPD ASC loops
were estimated (attachment figure 3). Actually the expected suppression of the fluctuation is poor. The yaw loop seems to have
too low gain, but in fact increasing gain is not so beneficial as there is no reasonable phase margin at higher frequency.

With the estimated openloop transfer functions and the measured free-running angular fluctuation, the suppressed angular spectra can be
estimated (attachment figure 4). This tells us that the suppression of the angular noise at around 3Hz is not sufficient in both pitch and yaw.
As there is no mechanical resonance in the actuator response at the frequency, intentional placement of poles and zeros in the servo filter is necessary.

4) Newly designed ASC filter

Here is the new design of the QPD ASC servo (attachment figure 5). The target upper UGF is 10Hz with the phase margin of 50 to 60deg.
The servo is AC coupled so that we still can tweak the alignment of the mirror.

As this servo is conditionally stable, at first we should close the loops with stable filter and then some boosts should be turned on.
Estimated suppressed fluctuation is shown in the attachment figure 6. We can see that the fluctuation was made well white between 0.5Hz to 10Hz.

The filter design is shown as follows:


Pitch
FM1: zero at 0Hz, pole at 2000Hz, gain at 2000Hz = 2000

FM3: (boost)
zero: f: 0.5Hz q: 1  /  4.5Hz, q: 1 / f: 1Hz, q: 3
pole: f: 2Hz q: 3  / f: 2.7Hz, q: 2  / f: 1Hz, q: 15

FM9: (HF Roll-off)
pole: f: 40Hz q: 1.7
 
Servo gain: -0.028

Yaw
FM1: zero at 0Hz, pole at 2000Hz, gain at 2000Hz = 2000

FM3: (boost)
zero: f: 0.7Hz q: 2  /  3Hz, q: 7 / f: 2Hz, q: 6
pole: f: 1.02Hz q: 10  / f: 4.5Hz, q: 0.8  / f: 1.5Hz, q: 10

FM9: (HF Roll-off)
pole: f: 40Hz q: 1.7
 
Servo gain: -0.0132


 

Attachment 1: PRM_OPLEV.pdf
PRM_OPLEV.pdf
Attachment 2: PRM_QPD.pdf
PRM_QPD.pdf
Attachment 3: OLTF_design.pdf
OLTF_design.pdf
Attachment 4: QPD_spe.pdf
QPD_spe.pdf
Attachment 5: OLTF_design2.pdf
OLTF_design2.pdf
Attachment 6: QPD_spe2.pdf
QPD_spe2.pdf
Attachment 7: 140328.zip
  9773   Tue Apr 1 22:03:44 2014 KojiSummaryASCNew PRM ASC is running

[Koji Jenne]

New PRM ASC was implemented. [to be cnt'd]

  9777   Wed Apr 2 19:50:12 2014 KojiSummaryASCNew PRM ASC is running

As the designed ASC filters in this entry had too little phase margins (~10deg), I had to compromise the servo design.

The design was modified and tested again. This will be reported by a following entry.

Incidentally, I have adjusted the demodulation phases of REFL33/55/165 for PRMIsb so that the PRCL is eliminated from the Q signals.

REFL33    125.5 deg -> +136.5 deg
REFL55      45.0 deg -> +  25.0 deg
REFL165   -79.5 deg -> +  44.5 deg

This change of the demod phase for REFL165 was a bit surprising.
I did not check the sign, so it could be -135.5 deg. But still this is a bit change.

  9779   Wed Apr 2 23:08:51 2014 KojiSummaryASCNew PRM ASC is running

The new PRM ASC design


Pitch
FM1: zero at 0Hz, pole at 2000Hz, gain at 2000Hz = 2000

FM5: (boost)
zero: f: 0.5Hz q: 1  /  4Hz, q: 2 / f: 1Hz, q: 3
pole: f: 2Hz q: 3  / f: 2.7Hz, q: 2  / f: 1Hz, q: 15

FM9: (HF Roll-off)
pole: f: 40Hz q: 1/Sqrt(2) (2nd order butterworth)

Servo gain: -0.023

Yaw
FM1: zero at 0Hz, pole at 2000Hz, gain at 2000Hz = 2000

FM5: (boost)
zero: f: 0.5Hz q: 1  /  4Hz, q: 2 / f: 1.5Hz, q: 10
pole: f: 1.02Hz q: 10  / f: 3Hz, q: 5  / f: 2Hz, q: 6

FM9: (HF Roll-off)
pole: f: 40Hz q: 1/sqrt(2)
 
Servo gain: -0.027


The loop gains were adjusted to have the UGFs of 10Hz. The measured openloop transfer functions were compared with the model.
The transfer functions for yaw are well matched. However, the pitch ones don't. It seems that the pitch loop has extra low pass
which I can't locate. The possibility is the analog electronics of the pitch loop.


The effect of the control between 0.3Hz to 3Hz are well represented by the model. The attachment 2 shows the free running
angle fluctuation, the ones with the control engaged, and the estimated spectra. Indeed, the estimated spectra well represent
the measured angular spectra.

Attachment 1: PRM_QPD.pdf
PRM_QPD.pdf
Attachment 2: QPD_spe.pdf
QPD_spe.pdf
  9788   Tue Apr 8 10:44:53 2014 KojiUpdateLSCPlaying with PRMI + 2 arms

I vaguely remember that the ALS count (Phase Tracker output) is converted to Hz@532nm by a factor  ~20kHz/cnt.
This means the calibration for the IR frequency is 10kHz/cnt.

If this is true 100cnt is 2MHz. Isn't it too big?

Assuming 38.5m for the arm length, FSR is 3.89MHz. (~389cnt)

Our sideband is at integer multiples of 11.03MHz. So...

1xf1 is 0.62MHz (62cnt) away from the carrier
2xf1 is 1.24MHz (124cnt)
3xf1 is 1.86MHz (186cnt)
5xf1=1xf2 is 0.79MHz (79cnt)
10xf1 = 2xf2 is 1.58MHz (158cnt)
15xf1 = 3xf2 is 1.52MHz (152cnt)

So we have to be well with in 62cnt to avoid resonating modulation sidebands.

There maybe some mistake in the factors.
e.g. Phase Tracker calibration is not correct, or CARM ALS OFFSET has factor 2 different calibration from the arm ALS offset.

  9800   Fri Apr 11 12:21:27 2014 KojiUpdateLSCCARM and DARM both on IR signals!!!!!!!!!

About the ADC range,

According to the elogs, DARM = AS55Q/400. So in the current level, the error has +/-40cntpp (even if I ignore the whitening).

The arm transmission this time was 0.1-0.3. This will go up to 100~300. So we potentially increase the AS55Q optical gain by factor of 1000.

So we get +/-40000. This is already too much. If we consider the whitening, the situation is more tough.

We need to lower the whitening gain. If it is not enough, we need to lower the power on the PD.

How much was the whitening gain for AS55 this time?

Quote:

 DARM_IN1_getsSmaller.png

 

  9803   Fri Apr 11 16:04:31 2014 KojiUpdateLSCcongratulation

It's just one of the stepping stones, but not yet a mile stone.
Keep going forward!

  9812   Tue Apr 15 08:55:57 2014 KojiUpdateLSCAnalog phasing of REFL11 and REFL55

I have never used such a long cable for RF phase adjustment. The speed of the signal is 2e8 m/s and the frequency is ~10e6 Hz.
This means that the wavelength is only about 20m. How could you end up with ~100meters?
The convenient way to remember the cable delay is "1m, 1MHz, 2deg". This gives us ~1.5m for 11MHz and 34deg.

In fact, 1 degree of phase shift is not 1/(2 pi freq) second of delay, but f/360.

For such a precise phase adjustment, it is better to calibrate the delay with the network analyzer.

Quote:

We calculated that about 1 degree of phase shift is about 1/(2 * pi * freq), or about 1.4e-8 seconds of delay for 11MHz.  We took the speed of light in the cables to be about 2/3*c, so 1.4e-8 * 2e8 = 2.9 meters per degree for 11MHz.  Since REFL11 was 34 degrees from 0, we estimate that we need to add about 98 meters of cable to the REFL11 signal path.  The same calculation for 55 MHz, but with a 15 degree shift required, gives 8.8 meters of cable to be added to the REFL55 signal path.   

 

  9815   Tue Apr 15 16:21:18 2014 KojiUpdateIOOMC2 LSC offset was set to be -5000

Yesterday, MC2 alignment was slipping all day. Even when the WFS was off (i.e. there wa sno actuation), I had continual misalignment caused by MC2

I was afraid that the MC2 mirror is on a bistable position somehow. So I gave -5000 offset on the MC2 LSC. We'll see how it makes the MC happier.

  9847   Thu Apr 24 11:19:50 2014 KojiUpdateLSCLocking without TRY

This seems the ever best stability at the zero offset PRFPMI.

Can you look at REFLDC in this data stream too? How was it promising?

  9852   Thu Apr 24 23:55:31 2014 KojiUpdateLSCY end whitening board

The main problem was a panel fixing bolt that caused the short circuits between power supply layers.
This burned the PCB and secondarily caused permanent short circuit between +15V/-15V/+5V layers.

Diagnosis

- The resistances between +15V, +5V, and -15V were low. The resistance between +15V and -15V is 13 Ohm.
  The one between +5V and -15V is 7Ohm. And the one between +15 and +5 is 19Ohm. So the situation is

                o -15V
                |
+15V o-(13 Ohm)-+-(9 Ohm)-o +5V

Even after removing all of the active components from the board, they remained the same.

- The tantalum caps were removed from the board and it was confirmed that they are not the cause of the issue.

- The panel was removed from the module for the component migration to a spare board (to be described in the other entry).
I found that the screw hole and the screw have burnt marks. The screw need an insulation tube to avoid short circuit.
The other screw was also bare. The spare board has the screws with the insulation tubes.

 

Attachment 1: P4245550.JPG
P4245550.JPG
  9854   Fri Apr 25 10:43:57 2014 KojiUpdateLSC(Fixed) Y end whitening board

I went to WB and found the last spare module of D990399 revB. We need to thank Frank for his foresight.

The original (=broken) board had various modifications from this revB.
I had to check the schemaric diagram and the difference between the boards and migrate some of the SMD components from left to right.


Here is the deciphered features of the QPD whitening board:
- The input stage is a VGA amp (AD602). It has the internal input impedance of 100 Ohm. The series resister
  of 909 Ohm gives us 1/10 voltage division! It is more tricky as the QPD (D990272) has the output impedances of 50Ohm
  (for the both side of the differential out) and on resistance of MAX333A. So it could have been deviated by ~10% from the nominal.

- Variable gain control: The input has 1/10 voltage division. The gain is fixed at the unity. In total the gain of the variable control stage is 1/10.
  This gives us the gain range of +42dB/-22dB for +10V/-10V. The actual range is limited to be -10~30dB.

- Whitening stages. Each channel has two sets of the whitening path and the bypass path.
  They could be switched by binary control inputs but I permanently enabled the whitening by pulling the MAX333 control inputs to the ground.
  The whitening zero and pole are at 4.02Hz and 40.6Hz.

  Each bypass path has an additional cap of 220pF in parallel to 35.7kOhm (R101 and R103 for CH1), resulting in the pole at 20.2kHz.
  Each whitening paths had a 5.6nF cap (C53 and C64). This cap was replaced with 350pF, resulting in the move of the pole freq from 800Hz to 12.7kHz.

- There are two anti-aliasing stages which were designed for 2kHz sampling rate. They are identical sallen key 2nd-order LPFs with fc=766Hz and Q=0.74 (~ butterworth).
  As all of these caps were removed, they are just voltage followers now.

- The final stage (AD620) has the gain resister of 16.5k. The gain is 1+(49.4k/16.5k) = 3.99.

- The 4pin lemo connector (J8) was removed from the board. We instead installed an isolated BNC connector on the panel for the thorlabs PD serving as the high gain PD.

- There is a daughter board for the high gain PD. This seems to be the butterworth low pass filter with fc=~30kHz.
  The differential output of the daughter board is connected to pin 17 and 18 of J10 (S5 Out and Rtn).

- The input of the daughter board is differential (AD620). Therefore the LEMO connectros next to the BNC were wrapped with Kapton tapes for isolation.

Board test at the workbench.

- The test required two dual power supply as the unit requires +/-5V and +/-15V.

- The four channels were tested with the signal injection. 1kHz input yielded 20mVpp across the AD602 input. The output of the 1st whitening stage was
  60mVpp. This makes sense as the gain of the AD620 is -10dB (1/10 and 10dB). The output of the 2nd whitening stage was 600mVpp.
  Finally the output of the output stage was confirmed to be 2400mVpp. This was confirmed for four channels.

- The daughter board output was also checked. The gain is the unity and flat upto ~10kHz.

Board installation

- Jenne installed the module. This time there was no smoke.


Gain mystery

- It was not sure how the whitening gains have been given.

- The corresponding database entry was found in /cvs/cds/caltech/target/c1auxey/ETMYaux.db as

grecord(ao,"C1:ASC-QPDY_S1WhiteGain")
grecord(ao,"C1:ASC-QPDY_S2WhiteGain")
grecord(ao,"C1:ASC-QPDY_S3WhiteGain")
grecord(ao,"C1:ASC-QPDY_S4WhiteGain")

- The gains for S2-S4 were set to be 30. However, C1:ASC-QPDY_S1WhiteGain was set to be 8.62068.
And it was not writable.

- After some investigation, it was found that the database was wrong. The DAC channel was changed from S100 to S0.
The corrected entry is shown here.

grecord(ao,"C1:ASC-QPDY_S1WhiteGain")
{
        field(DESC,"Whitening gain for QPDY Seg 1")
        field(DTYP,"VMIVME-4116")
        field(OUT,"#C0 S0 @")
        field(PREC,"1")
        field(EGUF,"42")
        field(EGUL,"-22")
        field(EGU,"dB")
        field(LINR,"LINEAR")
        field(DRVH,"30")
        field(DRVL,"-10")
        field(HOPR,"30")
        field(LOPR,"-10")
}

- Once c1auxey was rebooted, the S1 whitening gain became writable. Now all of the channels were set to be +30dB (max).

 

Attachment 1: D990399-B_40m.pdf
D990399-B_40m.pdf D990399-B_40m.pdf D990399-B_40m.pdf
Attachment 2: P4245552.JPG
P4245552.JPG
Attachment 3: P4245553.JPG
P4245553.JPG
Attachment 4: P4245551.JPG
P4245551.JPG
  9860   Sun Apr 27 20:26:19 2014 KojiUpdateLSCPhase Tracker servo characterization

The measured open loop TF of the ALS Phase Tracker loop for each arm was characterized by an empirical model on LISO.

The model for the open loop TF has pole 1m instead of the one at DC as LISO has a difficulty to model it.
Digital time delay and the sampling effect seem to be well represented by a zero at ~8kHz and delay of  ~60us.
(cf 16kHz sampling => 61us)

The XARM phase tracker has the UGF of 1.5kHz. This is too low because
1) The phase rotation at 100Hz is visible in the plot.
2) We don't much care about the closed loop bump in the phase tracker as long as the phase tracker keeps its continuity.

So I suggest to increase the gain so that we have the UGF of 3kHz. (phase margin: 24deg)

The red curve in the plot is the closed loop response calculated by CLTF =  - OLTF / (1-OLTF).

The model results are used in the ALS servo models.

Attachment 1: ALSX_PTTF.pdf
ALSX_PTTF.pdf
Attachment 2: ALSY_PTTF.pdf
ALSY_PTTF.pdf
  9861   Sun Apr 27 21:30:59 2014 KojiUpdateLSCALS servo characterization

The measured openloop TF of the ALS servo for each was characterized by a ZPK model.

The openloop TF can be modeled by:

1) Filter TF obtained from foton
2) Actuator response with appropriate assumption
3) Phase tracker closed loop TF
4) Delay caused by the digital control
5) anything else

For 1) ZPK models of the servo filter was obtained from foton. It turned out that the TF of FM5 doesn't match with the ZPK model in foton.
Therefore the TF was exported and fitted with LISO. This seems to be related to the pole frequency (3kHz) which is too close to Nyquist frequency (8kHz).

FM(:,1)  = zero1(f,5).*pole1(f,0.001)*5000;
FM(:,2)  = zero1(f,1).*pole1(f,0.001)*1000;
FM(:,3)  = zero2(f,4.5,1.4619).*pole1(f,0.001).*pole1(f,0.001)*20.2501*1e6;
FM(:,4)  = zero2(f,35,2).*pole2(f,3,3).*zero1(f,3000).*pole1(f,1).*pole2(f,3000,1/sqrt(2)).*pole1(f,700).*zero1(f,10).*zero1(f,350).*136e1;
FM(:,5)  = zero1(f,1).*pole1(f,4.010e3).*pole2(f,17.3211e3,1.242).*zero2(f,18.865e3,100e3);
FM(:,6)  = zero2(f,3.2,0.966775).*pole2(f,3.2,30.572);
FM(:,7)  = zero2(f,16.5,2.48494).*pole2(f,16.5,78.5807).*zero2(f,24.0,2.22483).*pole2(f,24.0,7.03551);
FM(:,8)  = 1;
FM(:,9)  = zero2(f,7.50359,1.07194).*pole2(f,1.43429,0.717146)*27.5653;
FM(:,10) = 1;

dc_gain = 14;

FM1/2/3/5/6/7/9 are used for the control.

For 2), a resonant freq of 0.97 with Q of 5 was assumed.

The model for 3) was obtained by the previous entry.

Now the measured TF was divided by the known part of the model 1) ~ 3) and empirically fitted in LISO.

### XARM ###
pole 392.5021429051 698.1992431753m
zero 42.3128869460k 31.0954443799m
pole 589.2716424428 2.8325268375
factor 8.3430140244
delay 34.7536691023p

### YARM ###
pole 416.2463334253 743.2196174175m
zero 97.9161062704M 114.6703921876m
pole 626.0463515310 2.7671041771

factor 9.0045911761
delay 34.0945727358p

These compensation TF have weird TF. Probably the frequency response of the delay and the analog AA/AI filters without the high frequency data
led the LISO make up this. I'm requesting Masayuki to provide the AA/AI data to make the estimation more reasonable.
For the servo modeling, this is sufficient and we'll go a head.

The results of the OLTF modeling are attached.

Attachment 1: ALSX_OLTF.pdf
ALSX_OLTF.pdf
Attachment 2: ALSY_OLTF.pdf
ALSY_OLTF.pdf
  9862   Mon Apr 28 10:24:10 2014 KojiUpdateLSCerror signal characterization

As we now have the loop model, we can characterize the error signals.

We have the following data:

1) Free-running ALS error signals (i.e. phase tracker output) calibrated in Hz (for 532nm) (blue)
2) Controlled ALS error signals calibrated in Hz (for 532nm) (red)
3) ALS error signals measured with X and Y arm locked with the IR PDH. (black)
    This is likely to represent the sensing noise of the beatnote detection

from 2) we can derive the similar quantity as 1)
4) Estimated free-running ALS error signals from the controlled signals (green)

Remarks:

- From 1) and 4) we can see that the phase tracker is not perfectly linear. It seems that fast fringing of the phase tracker is causing upconversion.

- From 2) and 3) the servo loops don't have enough gain between 3Hz and 20Hz. On the other hand they have too much gain bekow 3Hz.

Attachment 1: ALSX_SPE.pdf
ALSX_SPE.pdf
Attachment 2: ALSY_SPE.pdf
ALSY_SPE.pdf
  9863   Mon Apr 28 10:34:51 2014 KojiUpdateLSCnew ALS servo design

Based on the evaluation of the error signals, the new servo was designed.

Concept:
- Don't touch the locking filters. (i.e. FM5)
- Sacrifice some phase at 150Hz to increase the gain between 3-20Hz.
- As resonant gains costs the phase without increasing the LF gains, replace them with a poles for the integrators.


FM(:,1) = zero2(f,.5,.7).*pole2(f,0.001,.7)*(0.5/0.001)^2;
FM(:,2) = zero2(f,5,2).*pole2(f,3,3).*pole1(f,1).*zero1(f,5)*5*(5/3)^2;
FM(:,3) = zero2(f,25,.7).*pole2(f,3.2,10)*(25/3.2)^2; % Zero crossing
FM(:,4) = zero2(f,35,2).*pole2(f,3,3).*zero1(f,3000).*pole1(f,1).*pole2(f,3000,1/sqrt(2)).*pole1(f,700).*zero1(f,10).*zero1(f,350).*136e1;
FM(:,5) = zero1(f,1).*pole1(f,4010).*pole2(f,17.3211e3,1.242).*zero2(f,18.865e3,100e3);
FM(:,6) = zero2(f,5,2).*pole2(f,10,2).*pole2(f,16.5,30).*zero2(f,30,2);
FM(:,7) = 1;
FM(:,8) = 1;
FM(:,9) = 1;
FM(:,10) = 1;
dc_gain = 14;

FM1/2/3/5/6 are expected to be used for the control.


FM1: Boost below 0.5Hz. This does not cost the phase margin.
FM2: Increase the gain below 5Hz. This hardly cost the phase margin.
FM3: Boost below 25Hz. This is the main phase cost at UGF. This has a complex pole pair at 3Hz with Q=10 to supress the stack motion.
FM6: zero-pole-pole-zero combination to boost the gain between 5 to 30Hz. This eats the phase margin a little.

Note that the phase tracker gain for the X arm was increased by factor of 2.5.

Attachment 1: ALSX_OLTF_new2.pdf
ALSX_OLTF_new2.pdf
Attachment 2: ALSY_OLTF_new2.pdf
ALSY_OLTF_new2.pdf
  9864   Mon Apr 28 10:48:48 2014 KojiUpdateLSCnew ALS servo design: comparison

Comparison of the new and old servo OLTF
The new servo has the same UGF, slightly less phase margin, and more gain between 1.5 and 25Hz.

Attachment 1: ALSX_OLTF_new.pdf
ALSX_OLTF_new.pdf
Attachment 2: ALSY_OLTF_new.pdf
ALSY_OLTF_new.pdf
  9865   Mon Apr 28 10:59:54 2014 KojiUpdateLSCNew ALS servo design: expected error signals

The expected error signals derived from the estimated free running error signals of the ALS.

1) Previously estimated free-running noise (blue)
2) Previous in-loop ALS error signal (red)
3) Estimated error signal with the new servo (green)
4) Out-of-loop noise of the ALS with the arm controlled with the IR PDH (black)

Now the error signal (green) is expected to be very white.
The suppressed noise between 3 to 20Hz are below the sensing noise level.
There seems a little excess at 24.5Hz and 28Hz. If it is limiting the RMS, we need to take care of them.

Attachment 1: ALSX_SPE_new.pdf
ALSX_SPE_new.pdf
Attachment 2: ALSY_SPE_new.pdf
ALSY_SPE_new.pdf
  9866   Mon Apr 28 11:03:57 2014 KojiConfigurationLSCNew ALS servo implemented for the X arm

The new ALS/LSC servo was implemented for the X arm.

I'll upload more data later but here I make quick remarks:

- We need to give the gain of 12 to have correct UGF with the ALS.

- With this servo, the Xarm PDH lock oscillates with the gain of 0.02. We need to lower the gain to 0.015.
  Also FM trigger should be changed not to trigger unused FMs (FM7/8)

  9867   Mon Apr 28 11:08:11 2014 KojiUpdateLSCNew ALS servo design: expected error signals

Here are the MATLAB scripts and LISO codes for all of these servo analyses

Attachment 1: 140421_ALS_servo.zip
  9874   Tue Apr 29 01:10:16 2014 KojiConfigurationLSCNew ALS servo implemented for the X arm

New ALS servo performance

Attachment 1:

Comparison between the old (orange) and new (red). The new error signal (red) is suppressed like a white noise as expected.

Comparison between the out-of-loop evaluation (black) and the in-loop signal (red). Below 50Hz the out-of-loop is limited by the sensor-noise like something.
This out-of-loop stability was measured with the ALS stayed at the top of the resonance and calibrated the POX11 error signal.

Attachment 2:

New ALS servo with the LSC PDH signal. When the PDH signal is used for the control, FM4 is additionally used.
In this condition, the error signal was measured and calibrated into frequncy noise (Hz/sqrtHz).

By comparing the POX (with the new servo) and POY (with the old servo) signals, one can see that the new servo has better supression below 30Hz with almost no cost at ~100Hz.

Attachment 1: ALSX_SPE.pdf
ALSX_SPE.pdf
Attachment 2: ALSX_PDH_SPE.pdf
ALSX_PDH_SPE.pdf
  9875   Tue Apr 29 10:01:25 2014 KojiConfigurationGeneralnetgpibdata is working again now

I've moved the WB network analyzer to the OMC lab. The 40m network analyzer is not in service for the MC monitoring.
I setup the configuration so that the same command gives us the same spectrum measurement.

  9887   Thu May 1 00:13:21 2014 KojiUpdateLSCALS X beat setup aligned

I saw big misalignment on the GTRX camera, I went to the PSL table and aligned the beat beams.

I disconnected the RF out of the X beat PD and  connect an oscilloscope.
The beat amplitude was 15mVpp at the beginning and is 60mVpp right now.
I checked the alignment on this RF PD and the DC PD as well as the spot on the CCD.

The RF cable was connected again.

Jenne and I ran the ALS and scanned the arm cavity. We had the impression that the noise level of the ALS improved,
but I don't have correctly calibrated measurement. Let's do it tomorrow in the day time.

The Yarm beat alignment look awful. We should align this too.

  9905   Fri May 2 14:31:26 2014 KojiUpdateLSCALS Y beat setup aligned

Please check the X&Y ALS out-of-loop stability. Use fine resolution (BW0.01). Calibrate the POX/POY in Hz.

  9939   Fri May 9 21:18:51 2014 KojiUpdateGreen LockingReverted X green light power

It is actually very tricky to measure the green power at the output of the doubling crystal as the IR often leaks into the measurement.
I checked the green beam powers on the X/Y/PSL tables.

CONCLUSION: There is no green beam which exceeds 5mW anywhere in the 40m lab.

Note: The temperature of the doubling crystal at the X end was optimized to have maximum green power. It was 36.3degC and is now 36.7degC.

X END:

When the angles of the wave plates are optimized, we have 539mW input to the doubling crystal.
With the Xtal temperature of 36.7degC, where the green power is maximized, the power right after
the harmonic separator (H.S.) was 9.6mW.

Xtal temp 36.7degC   ~~~
                      |

--539mW@IR-->{Xtal}-->/-->9.6mW-->{Mirror}-->4.69mW-->{Mirror}-->4.54mW-->{Faraday}
                    (H.S.)

If we believe these 4.69mW and 4.54mW are purely from the green, we have 4.8mW right after the H.S.
This corresponds to the conversion efficiency of 1.6%/W (cf. theretical number 2%/W)

By disabling the heating of the crystal, we can reduce the green light by factor of 60. But still the reading right after the H.S. was 5.3mW

Xtal temp 29.2degC   ~~~
                      |
--539mW@IR-->
{Xtal}-->/-->5.3mW-->{Mirror}-->285uW-->{Mirror}-->74.3uW-->{Faraday}
                    (H.S.)

Naively taking the difference, the green beam right after the H.S. is 4.4mW.

In either cases, the green power right after the oven is slightly less than 5mW.

Y END:

When the angles of the wave plates are optimized, we have 287mW input to the doubling crystal.
With the Xtal temperature of 36.0degC, where the green power is maximized, the power right after
the harmonic separator (H.S.) was 0.86mW.

Xtal temp 36.0degC   ~~~
                      |

--287mW@IR-->{Xtal}-->/-->0.86mW-->
                    (H.S.)

When the temperature was shifted to 39.2degC, the reading after the H.S. was 70uW. Therefore the contamination by the IR is small
in this setup and we can believe the above reading in 70uW accuracy. This 0.86mW corresponds to the conversion efficiency of 1.2%/W.

PSL

The incident IR is 80mW. We have 170uW after the H.S., which corresponds to the conversion efficiency of 2.6%/W. Maybe there is some IR contamination?
From the vacuum chamber total 1mW of green is derivered when both arms are locked and aligned.

Thus the total green power at the PSL table is less than 5mW.

  9992   Mon May 26 07:59:23 2014 KojiUpdateElectronicsAmplifier removed from BeatX path

And the out-of-loop level of the ALSX compared with the previous measurement is ...?

Quote:

I just realized that I forgot to elog this, but yesterday afternoon I bypassed the amplifier in the BeatX path, and now the X beatnote is about -27dBm.  Arms lock nicely with ALS.

 

  10001   Wed May 28 19:15:38 2014 KojiUpdateLSCX green broadband PD NOT working

If the PD is the suspect, just pull it from the table and bring it to the PD testing setup.

The transimpedance of the PD should be ~2000 Ohm for both of the RF and DC outputs.

The test setup gives you the systematic opportunity for examination of the signal line.
Check the signal level with the active probe.

Once the broken component is found replace it. You are supposed to have the replacement
components on the blue tower.

  10004   Thu May 29 14:40:17 2014 KojiUpdateLSCHigh Bandwidth power recycled Yarm.

Wait. It is not so clear.

Do you mean that the IFO was locked with REFL11I for the first time?

Why is it still in the "low finesse" situation? Is it because of misalignment or the non-zero CARM offset?

  10012   Mon Jun 9 16:55:31 2014 KojiSummaryElectronicsBBPD D1002969-v8 transimpedence measurement

How is the modulation depth assumed in the calculation?

If you don't know the modulation depth, you can't calibrate the transimpedance of each PD individually.

  10031   Thu Jun 12 11:03:11 2014 KojiFrogsGeneralWorld Cup Soccer 2014

world_cup.jpg

  10038   Fri Jun 13 19:09:44 2014 KojiUpdateIOOA blown fuse found on the euro card crate at 1X2 (IOO) rack.

[Rana Zach Koji]

We tracked down the MC locking issue to be associated with the power supply problem.
Replacing a fuse which had incomplete connection with the new one, the MC started locking.

We still have the MC autolocker not running correctly. This is solely a software problem.


We went down to the IOO electronics rack to investigate the electronics there. After spending
some time to poking around the test points of the MC servo board, we noticed that the -24V
power indicator on the MC demodulator module was not lit. In fact, Steve mentioned on Wednesday
that the -24V Sorensen supply had lower current than nominal. This actually was a good catch
but should have been written in the ELOG!!!

We traced the power supply wires for the crate and found one of the three -24V supply has no
voltage on it. Inspection of the corresponding fuse revealed that it had a peculiar failure mode.
The blown LED was not lit. The connection was not reliable and the -24V power supply was flickering.

We then replaced the fuse.This simply solved all of the issues on the MC servo board. The electronics
should be throughly inspected if it still has the nominal performance or not, as the boards were exposed
to the single supply more than a week. But we decided to try locking ability first of all.

Yes, we now can lock the MC as usual.

Now the newly revealed issue is MC autolocker. It was running on op340m but op340m does not want to run it now.
It should be closely investigated.

Also turning on WFS unlocks the MC. Currently the WFS outputs are turned off.
We need usual align MC / check spot position / adjust WFS QPD spots combo.

  10064   Wed Jun 18 21:37:11 2014 KojiUpdateIOOMC REFL investigation

[Jenne Koji]

We decided to check the situation of the REFL MC beam path.

- No resolution of the weird MC REFL DC increase
- The reflection from the PD was adjusted to hit the beam dump
- The MC WFS paths were aligned again


Detail:

We found that the reflected beam from the PD was hitting the mount of the beam dump.
So the entire MC REFL path was steered down such that the last steering mirror does not neet to steer the beam.
When the alignment was adjusted so that the reflection from PD hit the beam dump, the beam spot on the small mirror right before the PD
got a bit marginal but it seemed still OK after some tweak.

Then we looked at the reflection value. It is still about 6.5. No change.

As we messed up the entire MC REFL path, we aligned the MC WFS paths again.
This was done with the unlocked MC REFL beam. Once the cavity was locked,
it turned out that it was enough for the WFS too keep the MC locked.

  10065   Wed Jun 18 21:53:48 2014 KojiUpdateElectronicsChanges to the PD frequency response measurement system

Not "hot" current but "photo" current. Is this my bad!?

It was me who told Nichin that the DC transimpedance was 200Ohm. But according to this entry I checked the RF transimpedance of AS55 before.
In my code, the DC transimpedance was defined to be 50Ohm. If we believe it, 30mV corresponds to 0.6mA.

Quote:

The multimeter readout 30mV finally. Taking the transimpedence as 200ohm approx., the hot current is about 1.5mA.

 

  10085   Fri Jun 20 19:09:23 2014 KojiUpdateElectronicsTransimpedence measurement-BBPD

Oh, nice! This must be a new technique to have a higher transimpedance by breaking the PD.

Now both BBPDs are showing abnormally high impedance.
(Remember, you have not revised your
previous entry after my pointing out you have a bug in the code.)

You should break down the measurement into each raw numbers for validation.
And if this high impedance is still true, you should point out what is causing of this anomaly.

  10109   Fri Jun 27 20:52:30 2014 KojiUpdateCDSOTTAVIA was not on network

I came in the lab. Found bunch of white EPICS boxes on ottavia.
It turned out that only ottavia was kicked out from the network.

After some struggle, I figured out that ottavia needs the ethernet cable unplugged / plugged
to connect (or reconnect) to the network.

For some unknown reason, ottavia was isolated from the martian network and couldn't come back.
This caused the MC autolocker frozen.

I logged in to megatron from ottavia, and ran at .../scritpt/MC

nohup ./AutoLockMC.csh &

Now the MC is happy.

  10110   Fri Jun 27 23:49:56 2014 KojiUpdateGeneralIR beam found, TTs not aligned well yet

The IR beam was found on the PRM surface, some CCDs, and in the X arm. The TTs are not aligned well yet.

I'm leaving the IFO with the following state.


Status:

ITMY/ETMY - aligned to the given green beam. GTRY (no PSL green) 1.0~1.1

ITMX/ETMX - aligned to the green beam. The end PZT for the green beam was steered to have maximum GTRX (0.76 without PSL green)

TT1/TT2 - unknown alignment, TT1/TT2 are related such that the spot is on the POP CCD

PRM - aligned to the given IR beam (i.e. PRM spot on the REFL CCD)

BS - aligned to the given IR beam (i.e. ITMX spot on the AS CCD, The X arm is flashing)


Notes:

- ITMX was stuck in the suspension. it was caused by the EQ.

- When the X arm was aligned to the green beam, there was no green hitting on the GTRX PD. That's why the end PZT was adjusted.

- In order to earn more range for TT1, C1:IOO-TT1_YAW_GAIN and C1:IOO-TT1_PIT_GAIN were increased to 300 (100 nominal) and the limiter (at 500) were removed.

- The HeNe laser for BS/PRM does not emit the beam even with the driver turned on. Is there a hidden shutter or something? ==> Jenne

 


TO DO:

- Find the Y arm fringe by moving TT1 and TT2 without loosing the PRM/AS/POP spots.

 

  10144   Mon Jul 7 18:11:04 2014 KojiUpdateGeneralBeam Waists

- Plots should be directly attached on the elog. (Attaching codes in a zip is OK.)

- Plot legends should not touch or hide any data points.

- Don't exclude data points.

- The model for the beam profile fitting is incorrect: zr and w0 are dependent

- The code needs to be reviewed by someone for refinement.
  (
EricQ, or possibly Jamie, Jenne while he is absent).

  10148   Mon Jul 7 22:18:26 2014 KojiUpdatePSLPMC local oscillator is going wonky

It seems that there is no better chip in MiniCircuits line-up with the same form factor.
ERA-5 is the most powerful one in the ERA (or MAR) series.

If the output is ~0dBm we have MAR-6SM in stock. But I suspect that ERA-5 was driven at the power level close to its saturation (~18dBm).

If we allow different form factors, we have GVA-** or GALI-** in the market and also in the blue tower, in order to gain more performance margin.
If it is difficult to apply them, I would rather use another ERA-5 with enhanced heat radiation.

I'm sure that Downs has EAR-5 replacement.

  10153   Tue Jul 8 15:28:32 2014 KojiUpdatePSLPMC local oscillator is going wonky

Koushik and Koji try to fix the PMC oscillator issue. So we remove the module from the rack.
This means we don't have the PMC transmission during the work.

  10159   Wed Jul 9 00:47:22 2014 KojiUpdatePSLPMC local oscillator is going wonky

Koushik replaced an ERA-5 in the PC path. We put the module back to the rack and found no change.
The epics LO level monitor monitor is still fluctuating from 6~11dBm. We need more thorough investigation
by tracing the signals everywhere on the board.

Despite the poor situation of the modulation, PMC was locking (~9PM). Rana suspect that the PMC demodulation
phase was not correctly adjusted long time. 

Koushik has the measured power levels and the photos of the board. I'll ask him to report on them.

  10179   Thu Jul 10 18:25:18 2014 KojiUpdateGeneralCoupling telescope design

CFC-2X-C has a FIXED focal length of 2mm, but the collimator lens position is adjustable.
I'm not yet sure this affects your calculation or not as what you need is an approximate mode calculation;
once you couple the any amount of the beam into the fiber, you can actually measure it at the output of the fiber with a collimator attached.

  10194   Mon Jul 14 14:28:27 2014 KojiSummaryElectronicsTiming Issues of Mini Circuits UFC-6000: Solved

Looks good. Now you have the internal timer to verify the external clock.
If you can realize the constant rate sampling without employing the external clock, that's quite handy.

  10211   Wed Jul 16 01:35:16 2014 KojiSummaryLSCPython Wavelet peak finding for dramatic ALS - Red Resonance finding speedup

From the last plot:

- Subtracting the offset of 0.0095, the modulation depth were estimated to be 0.20 for 11MHz, 0.25 for 55MHz

- Carrier TEM00 1.0, 1st order 0.01, 2nd order 0.05, 3rd order 0.002, 4th order 0.004

==> mode matching ~93%, dominat higher order is the 2nd order (5%).

Eric: now we have the number for the mode matching. How much did the cavity round-trip loss be using this number?

  10214   Wed Jul 16 02:22:10 2014 KojiUpdateElectronicsTest run of PDFR system

Log-log ... 

  10223   Wed Jul 16 23:02:16 2014 KojiSummaryElectronicsBode Plots and complete Characterization of Frequency Counter

If I assume 1sample delay for 0.1s sampling rate, the delay is Exp[-I 2 pi f T], where T is the sampling period.

This means that you expect only 36 deg phase delay at 1Hz. In reality, it's 90deg. Huge!

Also there are suspicious zeros at ~1.6Hz and ~3Hz. This may suggest that the freq counter is doing some
internal averaging like a moving average.

It would be interesting to apply a theoretical curve on the plot. It's an intellectual puzzle.

  10232   Thu Jul 17 17:39:57 2014 KojiUpdateElectronicsPDFR debugging attempt : REFL11

What is the coupling factor between the RF in and the RF mon of the demodulator?
I don't assume you have the same amount RF power at those two points unless you have an RF amplifier in the mon path.

ELOG V3.1.3-