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ID Date Authordown Type Category Subject
  9641   Sun Feb 16 17:40:11 2014 KojiUpdateLSCFriday Night ALS

I wanted to try common/differential ALS Friday evening. I tried ALS using the LSC servo but this was not successfull.
The usual ALS servo in the ALS model works without problem. So this might be coming from the shape of the servo filter.
The ALS one has 1:1000 filter but the LSC one has 10:3000. Or is there any problem in the signal transfer between
ALS and LSC???


- MC:
Slow offset -0.302V

- IR:
TRX=1.18 / TRY=1.14, XARM Servo gain = 0.25 / YARM Servo gain = 0.10

- Green Xarm:
GTRX without PSL green 0.562 / with PSL green 0.652 -> improved upto 0.78 by ASX and tweaking of PZTs
Beat note found at SLOW OFFSET +15525
Set the beat note as +SLOW OFFSET gives +BEAT FREQ

- Green Yarm:
GTRY without PSL green 0.717 / with PSL green 1.340
Beat note found at SLOW OFFSET -10415
Set the beat note as +SLOW OFFSET gives -BEAT FREQ

- BEAT X -10dBm on the RF analyzer@42.5MHz / Phase tracker Qout = 2300 => Phase tracking loop gain 80 (Theoretical UGF = 2300/180*Pi*80 = 3.2kHz)
- BEAT Y -22dBm on the RF analyzer@69.0MHz / Phase tracker Qout = 400 => Phase tracking loop gain 300 (Theoretical UGF = 2.1kHz)

Transfer function between ALSX/Y and POX/Y11I @560Hz excitation of ETMX
POX11I/ALSX = 54.7dB (~0deg)
POY11I/ALSY = 64.5dB (~180deg)

POX11I calibration:

ALSX[cnt]*19230[Hz/cnt] = POX11I[cnt]/10^(54.7/20)*19230[Hz/cnt]
= 35.4 [Hz/cnt] POX11I [cnt] (Hz in green frequency)

35.4 [Hz/cnt]/(2.99792458e8/532e-9 [Hz]) * 37.8 [m] = 2.37e-12 [m/cnt] => 4.2e11 [cnt/m] (c.f. Ayaka's number in ELOG #7738 6.7e11 cnt/m)

POY11I calibration:

ALSY[cnt]*19230[Hz/cnt] = POY11I[cnt]/10^(64.5/20)*19230[Hz/cnt]
= 11.5 [Hz/cnt] POX11I [cnt] (Hz in green frequency)

11.5 [Hz/cnt]/(2.99792458e8/532e-9 [Hz]) * 37.8 [m] = 7.71e-13 [m/cnt] => 1.3e12 [cnt/m] (c.f. Ayaka's number in ELOG #7738 9.5e11 cnt/m)

  9647   Tue Feb 18 20:31:29 2014 KojiUpdateLSCALS not locking with LSC

Hmm. Wierd. Can you look at the TFs between ETMX-EXC and the error signals so that we can identify which one has these structures.

  9650   Wed Feb 19 00:35:23 2014 KojiUpdateLSCALS locked with LSC!

Great. I indeed disabled all of the triggers and the normalization during my trial but in vain.
So I'm curious this is actually because of the filter shape or not.

  9684   Mon Mar 3 11:55:39 2014 KojiUpdateCDSfb timing was off

We need to correctly setup crontab or rc.local for the frontend machines.

  9685   Mon Mar 3 17:35:10 2014 KojiUpdateLSCVarious demod phase measurement

I wanted to check how the refl signals looked like.
I decided to measure the demod phase where PRCL and MICH appear, one by one.

The method I used is to actuate PRCL or MICH at a fixed frequency and rotate the demod phase such that
the signal at the actuating frequency disappears.

For the PRCL actuation, PRM was actuated by the lock-in oscillator with the amplitude of 100cnt.
For MICH, the ITMX and ITMY was actuate at the amplitude of 1000cnt and 1015cnt respectively.

The script I used was something like this

ezcaread C1:LSC-REFL11_PHASE_R
ezcaservo -r C1:CAL-SENSMAT_CARM_REFL11_Q_I_OUTPUT C1:LSC-REFL11_PHASE_R -g 100 -t 60
ezcaread C1:LSC-REFL11_PHASE_R

"11" should be changed according to the PD you want to test.
"Q" should be changed to "I" depending on form which quadrature you want to eliminate the signal

The option "-g" specifies the servo gain. This specifies which slope (up or down) of the sinusoidal curve the signal is locked.
Therefore, it is important to flip the signal angle 180degree if a negative gain is used.


Note: Original phase settings before touching them

REFL11  - 19.2
REFL33   135.4
REFL55    48.0
RELF165 -118.5

 

Here in the measurement PRMI was locked with AS55Q (MICH) and REFL55I (PRCL)


Without no serious reason I injected a peak at 503.1Hz. This peak is not notched out by the servo. There may have been
some residual effect of the feedback loops.

PRCL: By elliminating the peak from the Q quadrature, we optimize the I phase for PRCL.

REFL11,   minimize PRCL in "Q", gain, -1, -19.3659 deg
REFL33,   minimize PRCL in "Q", gain, -1, 132.813 deg
REFL55,   minimize PRCL in "Q", gain, -1, 20.9747 deg
REFL165, minimize PRCL in "Q", gain, -1, -119.004 deg

MICH: By elliminating the peak from the I quadrature, we optimize the Q phase for MICH.
If PRCL and MICH appears at the same phase, the resulting angles shows an identical number.

REFL11,   minimize PRCL in "I", gain, -1, -28.4526 deg
REFL33,   minimize PRCL in "I", gain, -1, 65.9148 deg
REFL55,   minimize PRCL in "I", gain, -1, 12.4051 deg
REFL165, minimize PRCL in "I", gain, -0.1, -143.75 deg


Then, the signal frequency was changed to 675Hz where the notch filters in the servo is active.

PRCL: By elliminating the peak from the Q quadrature, we optimize the I phase for PRCL.

REFL11,   minimize PRCL in "Q", gain, 1, -19.5224 deg
REFL33,   minimize PRCL in "Q", gain, -1, 135.868 deg
REFL55,   minimize PRCL in "Q", gain, 1, 48.5716 deg
REFL165, minimize PRCL in "Q", gain, 1, -122.398 deg

MICH: By elliminating the peak from the I quadrature, we optimize the Q phase for MICH.
If PRCL and MICH appears at the same phase, the resulting angles shows an identical number.

REFL11,   minimize PRCL in "I", gain, -10, -73.7153 deg
REFL33,   minimize PRCL in "I", gain, -10, 135.5 deg
REFL55,   minimize PRCL in "I", gain, 10, -2.55868 deg
REFL165, minimize PRCL in "I", gain, -5, -156.135 deg


 

 

This is just a test of the REFL channels for the arms signals. ETMX or ETMY were actuated.

YARM

REFL11, minimize ETMY in "Q", gain 100 => C1:LSC-REFL11_PHASE_R = 145.694
REFL55, minimize ETMY in "Q", gain 100 => C1:LSC-REFL11_PHASE_R = -60.1512

XARM

REFL11, minimize ETMX in "Q", gain 100 => C1:LSC-REFL11_PHASE_R = 142.365
REFL55, minimize ETMX in "Q", gain 100 => C1:LSC-REFL55_PHASE_R = -68.6521

  9687   Mon Mar 3 22:21:43 2014 KojiSummaryLSCPRMIsb locked with REFL165I&Q

Successful PRMIsb locking with REFL165I/Q

My previous entry suggested that somehow the REFL165 signals show reasonable separation between PRCL and MICH, contrary to our previous observation.
I don't know what is the difference now. But anyway I took this advantage and tried to lock sideband resonant PRMI.

REFL165I was adjusted so that the signal is only sensitive to PRCL. Then REFL165I and Q were mixed so that the resulting signal shows.
(Next time, we should try to optimize the Q phase to eliminate PRCL and just use the I phase for PRCL.

At first, I used AS55Q for lock acquisition and then switched the MICH input matrix to REFL165.
Later I found that I can acquire PRMI just turning on AS55Q without turning off REFL165.

The REFL165 MICH signal had an offset of 15cnt. The lock was more robust and the dark port was darker once the MICH input offset was correctly set.


MICH OFS = 0
Turn on AS55Q only / or AS55Q + REFL156I/Q
Once it is locked and all of the FMs are activated, give -15.0OFS to MICH.
Turn off AS55Q.

Input ports:
AS55       WHTN: 21dB  demod phase -5.5deg
REFL165 WHTN: 45dB demod phase -156.13deg

Input matrix:
AS55Q x1.00 MICH
REFL165I x-0.035 + REFL165Q -0.050 MICH

REL165Q x+0.14

Triggers:
MICH POP110I 100up/10down / FM Trig FM2/3/6/7/9 35up 2down 5sec delay
PRCL POP110I 100up/10down / FM Trig FM2/3/6/9 35up 2down 0.5sec delay

Servo:
MICH OFS -15.0 / Gain -10 / Limitter ON
PRCL OFS 0 / Gain -0.02 / Limitter ON

Output matrix:
MICH ITMX -1.0 / ITMY +1.0
PRCL PRM 1.0

 

  9691   Wed Mar 5 11:33:10 2014 KojiSummaryLSC2 arm ALS->LSC transition - road map

Step by step description of transition from 2arm ALS to Common/Differential LSC for FPMI

- Step 0: Place the frequencies of the arm green beams at the opposite side of the carrier green.

- Step 1: Activate stablization loops for ALSX and ALSY simultaneously.
  (Use LSC filter modules for the control. This still requires correct handling of the servo and filter module triggers)

- Step 2: Activate stablization loops for ALS Common and Differential by actuating ETMX and ETMY

- Step 2 (advanced): Activate stabilization loops for ALS Common by actuating MC2 and ALS Differential by ETMX and ETMY

- Step 3: Transition from ALS Common to 1/SQRT(TRX)+1/SQRT(TRY). Make sure that the calibration of TRX and TRY are matched.
  The current understanding is that the offset for 1/SQRT(TRX)+1/SQRT(TRY) can't be provided at the servo filter. Figure out
  what is the correct way to give the offsets to the TR signals.

- Step 4: Lock Michelson with AS55Q and then POP55Q (PD not available yet) or any other PD, while the arms are kept off-resonant using ALS.

- Step 5: Reduce the TR offsets. Transition to RF CARM signals obtained from POP55I or REFL11I in the digital land.

- Step 5 (advanced): Same as test6 but involve the analog common mode servo too.

- Step 6: Transition from ALS Differential to AS55Q


Independent test: One arm ALS (To be done everyday)

- ALS resonance scan

- Measurement of out-of-loop displacement (or frequency) stability 

- Check openloop transer function


Independent test: Common Mode servo for one arm

- Reproduce Decmber CM servo result of transition from one arm ALS to CM servo
  Insert 1/sqrt(TRY) servo in between?

- How can we realize smooth transition from ALS to POY11?

  9698   Thu Mar 6 11:15:32 2014 KojiSummaryLSCStuck at step 2

You don't need to make transition from ALS X/Y to ALS C/D. Just stabilize the arms with ALS C/D from the beginning.

  9708   Mon Mar 10 21:12:30 2014 KojiSummaryLSCComposite Error Signal for ARms (1)

The ALS error (i.e. phase tracker output) is linear everywhere, but noisy.
The 1/sqrt(TR) is linear and less noisy but is not linear at around the resonance and has no sign.
The PDH signal is linear and further less noisy but the linear range is limited.

Why don't we combine all of these to produce a composite error signal that is linear everywhere and less-noisy at the redsonance?

This concept was confirmed by a simple mathematica calculation:

The following plot shows the raw signals with arbitorary normalizations

1) ALS: (Blue)
2) 1/SQRT(TR): (Purple)
3) PDH: (Yellow)
4) Transmission (Green)

The following plot shows the preprocessed signals for composition

1) ALS: no preprocess (Blue)
2) 1/SQRT(TR): multiply sign(PDH) (Purple)
3) PDH: linarization with the transmission (If TR<0.1, use 0.1 for the normalization). (Yellow)
4) Transmittion (Green)

The composite error signal

1) Use ALS at TR<0.03. Use 1/SQRT(TR)*sign(PDH)*(1-TR) + PDH*TR at TR>0.03
2) Transmittion (Purple)
 

Attachment 1: composite_linear_signal.nb.zip
  9711   Mon Mar 10 21:16:13 2014 KojiSummaryLSCComposite Error Signal for ARms (4)

The LSC model was modified for CESAR.

A block called ALSX_COMBINE was made in the LSC block. This block receives the signals for ALS (Phase Tracker output), TRX_SQRTINV, TRX, POX11 (Unnormalized POX11I).
It spits out the composite ALS signal.

Inside of the block we have several components:

1) a group of components for sign(x) function. We use the PDH signal to produce the sign for the transmission signal.

2) Hard triggering between ALS and TR/PDH signals. An epics channel "THRESH" is used to determine how much transmission
we should have to turn on the TR/PDH signals.

3) Blending of the TR and PDH. Currently we are using a confined TR between 0 and 1 using a saturation module. When the TR is 0, we use the 1/SQRT(TR) signal for the control,
    When the TR is 1, we use the PDH signal for the control.

4) Finally the three processed signals are combined into a single signal by an adder.


It is important to make a consideration on the offsets. We want all of ALS, 1/SQRT(TR), and PDH to have zero crossing at the resonance.
ALS tends to have arbitorary offset. So we decided to use two offsets. One is before the CESAR block and in the ALS path.
The other is after the CESAR block.
Right now we are using the XARM servo offset for the latter purpose.

We run the resonance search script to find the first offset. Once this is set, we never touch this offset until the lock is lost.
Then for the further scanning of the arm length, we uused the offset in the XARM servo filter module.

Attachment 1: ss1.png
ss1.png
Attachment 2: ss2.png
ss2.png
Attachment 3: CESAR_OFFSETS.pdf
CESAR_OFFSETS.pdf
  9712   Mon Mar 10 21:16:56 2014 KojiSummaryLSCComposite Error Signal for ARms (5)

After making the CDS modification, CESAR was tested with ALS.

First of all, we run CESAR with threshold of 10. This means that the error signal always used ALS.
The ALS was scanned over the resonance. The plot of the scan can be found in EricQ's elog.
At each point of the scan, the arm stability is limited by the ALS.

Using this scan data, we could adjust the gains for the TR and PDH signals. Once the gains were adjusted
the threshold was lowered to 0.25. This activates dynamic signal blending.

ALS was stabilized with XARM FM1/2/3/5/6/7/9. The resonance was scanned. No glitch was observed.
This is some level of success already.

Next step was to fully hand off the control to PDH. But this was not successfull. Everytime the gain for the TR was
reduced to zero, the lock was lost. When the TR is removed from the control, the raw PDH signal is used fot the control
without normalization. Without turning on FM4, we lose 60dB of DC gain. Therefore the residual motion may have been
too big for the linear range of the PDH signal. This could be mitigated by the normalization of the PDH signal by the TR.

  9713   Tue Mar 11 14:49:01 2014 KojiSummaryLSCImportant notice on the XARM servo

The nominal gain of the XARM for the POX11 error signal is 0.03 (instead of previous 0.3)

This is due to my increase of the gain in FM4 by 20dB so that we can turn of FM4 without changing the UGF when it is at 150Hz.

The YARM servo was not yet touched.

  9717   Tue Mar 11 15:21:08 2014 KojiSummaryLSCComposite Error Signal for ARms (1)

True. But we first want to realize this for a single arm, then move onto the two arms case.
At this point we'll need to incorporate frequency dependence.

  9718   Tue Mar 11 18:33:21 2014 KojiUpdateLSCComposite Error Signal for ARms (6)

Today we modified the CESAR block.

- Now the sign(X) function is in a block.

- We decided to use the linearization of the PDH.

- By adding the offset to the TR signal used for the switching between TR and PDH, we can force pure 1/sqrt(TR) or pure PDH to control the cavity.

Attachment 1: 14.png
14.png
  9728   Fri Mar 14 12:18:55 2014 KojiUpdateLSCComposite Error Signal for ARms (9)

Asymptotic cooling of the mirror motion with CESAR was tested.

With ALS and the full control bandwidth (UGF 80-100Hz), the actuator amplitude of 8000cnt_pp is required.

Varying control bandwidth depending on the noise level of the signal, the arm was brought to the final configuration with the actuator amplitude of 800cnt_pp.

Attachment 1: asymptotic_cooling.pdf
asymptotic_cooling.pdf
  9731   Mon Mar 17 12:02:55 2014 KojiSummaryGeneralIFO recovery / confirmed ETMX in trouble

I confirmed that we need to vent the chambers.

All of the mirrors have been aligned except for ETMX.

ETMX does not respond to the excitation by the UR and LR coils. Likely that the magnets are knocked off, or stuck in the coil.

PRM/SRM oplevs are too much off and can't be turned on. Need realignment of the beams on the QPDs.


- FB was down. FB restarted ("telnet fb 8087", then type shutdown)

- Aligned the MC mirrors.

- Aligned PRM. Look at the REFL. It was slightly mislisligned.

- AS has no beam. The Y arm was resonating with the green. So I determined that the TTs were the misaligned guys.

- Touched TT2 pitch with an increment of 0.1. Immediately the AS beam spot for ITMY was found. And the arm was resonating.

- The RM was further aligned. The bias sliders were saved and then the PRM was misaligned.

- Yarm was locked on TEM01. The ASS maximized the transmission for TEM01, and then the arm was locked on TEM00.
  The ASS aligned the arm and TTs. These values were saved.

- Yarm was aligned and I can see the AS spot. So I believe the BS is still well aligned.

- Aligned the PRM to reduce the ghost beams.

- Moved the ITMX to have Michelson fringes properly.

- Also aligned the SRM.

- Now ETMX was checked. Played with the alignment biases to see if the mirror was sticking on the coils. The mirror can rock a little, but it did not come back.

- Then, checked each magnets. 0.8Hz 1000cnt signals were injected to each coils (cf. C1:SUS-PRM_**COIL_EXC) to see how the mirror could react.
  The OSEM output and green spot on the ETMX cage were observed.

- Saw some response by actuating the UL, LL, SD coils.

- Saw no response from the UR and LR coils. They show the OSEM output of zero. Does this mean the magnets fell in the coils?

//Manasa// MC spot positions measured and they look alright with not much change from before the earthquake (attach)

Attachment 1: MCspots.png
MCspots.png
  9733   Mon Mar 17 20:14:34 2014 KojiSummaryGeneralIFO recovery / confirmed ETMX in trouble

I tried to take the photos of the magnets from outside. So far most suspicious was LL.
Otherwise, the magnets are OK.
(The SD magnet is the one with most reasonable response.)
Steve will try to take much more zoomed photo with Olympus. But the LL coil already showed some response in my observation in the morning.

ETMX_UL.JPGETMX_UR.JPGETMX_LR.JPGETMX_LL.JPG

  9735   Mon Mar 17 21:55:36 2014 KojiUpdateSUS4.4M local earthquake

It was little bit surprising to me but Rana's professorial rock'n roll excitation released its sticking on the unconfirmed thing by unconfirmed reason.

I aligned the Xarm manually and via ASS.

Now we are back in the normal state.

  9739   Tue Mar 18 21:19:22 2014 KojiSummaryIOOMC spot positions checked

MC spot sposition script was ran

/opt/rtcds/caltech/c1/scripts/ASS/MC/mcassMCdecenter

Found no notable beam position change before and after the earthquake

 

Attachment 1: MCASS.png
MCASS.png
  9747   Mon Mar 24 21:36:28 2014 KojiUpdateGeneralPower Failure

I'm checking the status from home.

P1 is 8e-4 torr

nodus did not feel the power outage (is it APS supported?)

linux1 booted automatically

c1ioo booted automatically.

c1sus, c1lsc, c1iscex, c1iscey need manual power button push.

  9750   Tue Mar 25 16:11:24 2014 KojiUpdateGeneralPower Failure

As far as I know the system is running as usual. I had the IMC locked and one of the arm flashing.
But the other arm had no flash and none of the arms were locked before kunch time.



This morning Steve and I went around the lab to turn on the realtime machines.

Also we took the advantage of this opportunity to shutdown linux1 and nodus
to replace the extension cables for their AC power.

I also installed a 3TB hard disk on linux1. This was to provide a local daily copy of our
working are. But I could not make the disk recognized by the OS.
It seems that there is a "2TB" barrier that the disk bigger than 2.2TB can't be recognized
by the older machines. I'll wait for the upgrade of the machine.

Rebooting the realtime machines did not help FB to talk with them. I fixed them.
Basically what I did was:

- Stop all of the realtime codes by running rtcds kill all on c1lsc, c1ioo, c1sus, c1iscex, c1iscey

- run sudo ntpdate -b -s -u pool.ntp.org on c1lsc, c1ioo, c1sus, c1iscex, c1iscey, and fb

- restart realtime codes one by one. I checked which code makes FB unhappy. But in reality
  FB was happy with all of them running.

Then slow machines except for c1vac1 and c1vac2 were burtrestored.

-------

Zach reported that svn was down. I went to the 40m wiki and searched "apache".
There is an instruction how to restart apache.

  9752   Wed Mar 26 11:30:07 2014 KojiUpdateGeneralPower Failure

Recovery work: now arms are locking as usual

- FB is failing very frequently. Everytime I see red signals in the CDS summary, I have to run "sudo ntpdate -b -s -u pool.ntp.org"

- PMC was aligned

- The main Marconi returned to initial state. Changed the frequency and amplitude to the nominal value labeled on the unit

- The SHG oven temp controllers were disabled. I visited all three units and pushed "enable" buttons.

- Y arm was immediately locked. It was aligned using ASS.

- X arm did not show any flash. I found that the scx model was not successfully burtrestored yesterday.
  The setting was restored using Mar 22 snapshot.

- After a little tweak of the ETMX alignment, a decent flash was achieved. But still it could not be locked.

- Run s/LSC/LSCoffset.py. This immediately made the X arm locked.

- Checked the green alignment. The X arm green is beating with the PSL at  ~100MHz but is misaligned beyond the PZT range.
  The Y arm green is locked on TEM00 and is beating with the PSL at ~100MHz.

  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.

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