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ID Date Authorup Type Category Subject
  8200   Thu Feb 28 06:51:17 2013 yutaUpdateRF Systemphase tracker: noise level

I measured noise level of the phase tracker by inputting constant frequency RF signal from marconi.
Measured frequency noise was ~2 Hz/rtHz @ 100 Hz. It's not so good.

What I did:
  1. Unplugged 11MHz marconi and put RF signal to the beatbox from this. Frequency and amplitude I put are 100 MHz and -3 dBm.
  2. Measured spectra of phase tracker outputs, C1:ALS-BEATX_FINE_PHASE_OUT, C1:ALS-BEATY_FINE_PHASE_OUT.
  3. Calibrated using the factor I measured (elog #8199).
  4. Put marconi back to orignal settings.


  - According to Schilt et al., this noise level is not so good.
  - By changing the delay-line cable length or optimizing whitening filter etc., we can improve this.

  8208   Fri Mar 1 16:58:37 2013 yutaUpdateLSCXarm oscillation stopped

POX11 oscillation at 630 Hz was stopped by installing 630 Hz resonant gain to LSC_XARM.
After few hours, oscillation stopped. So I removed the resonant gain.
Our guess is that 630 Hz peak is some violin mode or something, and it was excited somehow, and didn't stopped for very long time because of its high Q. It coupled into POY11 somehow (scattering, electronics, etc).

  8212   Sat Mar 2 05:53:15 2013 yutaUpdateLSCstable lock of PRMI

I tuned alignment, gains and filters to achieve stable lock of PRMI.
It now locks quite stably with UGF of ~100 Hz. Measured power recycling gain at maximum is ~ 25.

Locking details:
  == PRMI carrier ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -1, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = 0.3, feedback to PRM

  MICH servo is always on. PRCL loop turns on by trigger using POP DC. Boost filters and resonant gains turn on by triggers using POP DC.
  Gain normalization was not used.

Openloop transferfunctions:

  MICH: UGF ~90 Hz, phase margin ~40 deg
  PRCL: UGF ~100 Hz, phase margin ~50 deg (cf. Fitted gain was same as half-PRC: elog #8053)

Power recycling gain:

  POP DC when unlocked is 6, when locked is 2200-2500, and when dark is 0. So, power recycling gain is ~ 22 to 25. Value without any loss in PRMI is 45 (elog #6947). Alignment was pretty critical to achieve this recycling gain and stable lock.
  There was oscillation at 630 Hz when locked, which is similar to the one we saw in POX11 (elog #8203).


AS(top left), POP(top right), REFL(bottom left), and ETMYT(bottom right). ETMY was mis-aligned, but you can see the beam at ETMYT after PRMI was carrier locked.

MICH/PRCL coupling:

  I measured "sensing matrix" of PRMI by tickling PRM/ITMs/BS at 8.5 Hz and measuring 8.5 Hz peak height of AS55_Q, REFL55_I spectra during PRMI lock (attached is an example measurement of PRM). Below table is the result. AS55_Q has ~5% of sensitivity to PRCL compared with MICH. Also, BS introduces REFL55_I signal considerably. And also, there seems to be an imbalance in actuation efficiency between ITMX and ITMY.

actuation AS55_Q_ERR   REFL55_I_ERR
ITMX      +11.4        +0.80
ITMY      +33.0        +1.06
BS        +50.8        +1.90
PRM       - 0.7        +1.05

AS clipping:
  AS was clipped inside the vaccuum the other day(elog #8198). So, I tried to avoid AS clipping by aligning BS this morning. But it turned out that avoiding AS clipping by BS makes ITMX beam centering worse. Maybe we should center the beam on Yarm first next week.

 - calculate expected PRMI recycling gain with loss, PR2 filpped
 - beam centering on the arms
    - IPANG, IPPOS, Y green, X green
    - PRMI g-factor measurement

  8214   Sat Mar 2 20:09:12 2013 yutaUpdateRF Systemphase tracker: DAQ noise limited

[Koji, Yuta]

We found that our phase tracker noise is currently limited by the noise introduced in DAQ.
We confirmed that the frequency noise was improved from 2 Hz/rtHz to 0.4 Hz/rtHz by increasing the gain of the whitening filter.
The whitening filters should definitely be refined.

What we did:
  1. Put constant frequency RF input to the beatbox from Marconi and measured noise spectrum of the beatbox output(BEATX I) after the whitening filter with a spectrum analyzer. Noise floor level was ~0.2 Hz/rtHz at carrier frequency range of 15-100 MHz. Calibration factor of the beatbox output was ~380 mV/MHz.

  2. Measured noise spectrum of C1:ALS-BEATX_FINE_I_OUTPUT(figure below). The noise floor didn't change when there was RF input of 100 MHz from Marconi(blue) and DAQ input was terminated (green). Also, C1:ALS-BEATX_FINE_I_IN1(which is before unwhitening filter) showed a flat spectrum. These show our spectrum is limited by DAQ noise, which is introduced after the whitening filter.

  3. We increased the gain of whitening filter by x20 to show frequency noise performance can be improved by better whitening filter(red). But we can not use this setup as the other quadrature will be saturated by a too much gain at DC. Thus we need to carefully consider the signal level and the gain distribution of the whitening filters.

  - Better whitening filters. The current one consists of zero 1 Hz and pole 10 Hz with DC gain of 5 using SR560.
  - Better beatbox. We can increase the RF input power to the mixer and unify the preamplifier and the whitening filter in the box.

  8221   Mon Mar 4 16:46:31 2013 yutaUpdateSUSoplev calibration for PRM

[Manasa, Sendhil, Yuta]

We calibrated oplev for PRM. Calibration factor for C1:SUS-PRM_OL(PIT|YAW)_IN1 are;
  OLPIT: 15.6 +/- 0.3 counts/mrad
  OLYAW: 17.8 +/- 0.3 counts/mrad

We needed these values for g-factor measurement of PRC using angle dithering method.

What we did:
  1. Adjusted QPD offsets (C1:SUS-PRM_OL[1-4]_OFFSET) by zeroing the output when turned oplev laser was turned off.
  2. Centered PRM oplev beam on QPD using steering mirror.
  3. Mounted PRM oplev QPD on a xy-stage and centered the beam on QPD.
  4. Moved QPD in x and y using micrometers and measured dependance of C1:SUS-PRM_OL(PIT|YAW)_IN1 on QPD displacement.
  5. Measured the path length of PRM oplev returning beam. We get the in-vac path length using optical layout CAD. We measured out of vac path using scale and tape measure.
  6. Dismounted PRM QPD from the stage and put it back to the original position.

  1. Figures below are OLPIT/OLYAW dependance on micrometer displacement moved in x and y. Error bars are measured fluctuation in the signal.

moved in x:PRM_PIT.png       moved in y:PRM_YAW.png

  2. We fitted the result by error function to get slope at zero crossing point. We also linear-fitted the other degree of freedom to get cross coupling between x and y. Slopes we get were;

micrometer    OLPIT          OLYAW
moved in x    4.68 +/- 0.08  0.01 +/- 0.03
moved in y   -5.32 +/- 0.10  0.11 +/- 0.03    (counts/mm)

  3. Measured the path length of PRM oplev returning beam was 3340 +/- 20 mm. This gives you the calibration factors above.

  [Precision] According to Jamie's calculation, expected g-factor for PRC in PR2-flipped PRMI is 0.966/0.939 (elog #8068). We care about the g-factor change in ~0.01. Also, intra-cavity power dependance on mirror angle is proportional to 1/(1-g). So, we need to calibrate mirror angle in ~few 10 % of precision in order to get useful g-factor from angle dithering measurement. Measurement precision here meets this requirement.

  [x/y coupling] Measured x/y coupling was less than 2 %. We assumed gains in 4 QPD quadrants are same, and assumed QPD is mounted well in x/y axes. These assumptions are OK considering precision we need.

  [x/y difference] Calibration factors for OLPIT/OLYAW are different by ~10 %. This is not so crazy considering the incident angle on the QPD (~20 deg) and elliptic beam shape.

  8222   Mon Mar 4 17:32:26 2013 yutaBureaucracyGeneralflowchart for PRMI g-factor measurement

I made a very useful flowchart for the week. Our goal for the week is to measure g-factor of PRC in PRMI.


  8230   Tue Mar 5 06:27:14 2013 yutaUpdateLSCintra-cavity power dependence on mirror misalignment

I measured intra-cavity power dependance on mirror misalignment.
Intra-cavity power of PRC in PRMI degrates roughly 20 % when there's 0.5 mrad 5 urad misalignment. (edited by YM)
Currently, PRMI lock is not so stable, so it is hard to do this measurement and error bars are huge.

Measurement method:
  0. Align the cavity and lock.
  1. Misalign one optic and measure oplev output value and intra-cavity power.
  2. Also, dither the optic in pitch or yaw in 8.5 Hz and get demodulated amplitudes at 8.5 Hz of oplev output and intra-cavity power using tdsdmd.
  3. Misalign the optic again and do the same things.

  1. gives intra-cavity power dependence on mirror misalignment directly, but 2. should give better S/N because of dithering.

  /opt/rtcds/caltech/c1/scripts/dither/dithergfactor.py does these things, and ./plotgfactor.py plots the result.
  They work quite well, but it should be made better so that

  - it checks if the cavity is locked
  - automatically change the oplev calibration factor for each optic
  - automatically adjusts the region and modulation amplitude
  - read data with better error evaluation


PRMI alignment:
  Y green looks like it drifted quite a lot somehow. If we start aligning Yarm to Y green, we get AS and POP beam at different spot on camera compared with last week. Also, TRY and TRX only goes as high as ~0.7. Since we have A2L now (elog #8229), let's start using Yarm spot positions as input pointing reference.

PRMI locking details:
  Same as in elog #8212, but I changed gains in the lock acquisition mode.

  == PRMI carrier ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -0.2, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = 1.0, feedback to PRM

  I made gainx5 in LSC_MICH filter bank so that it increases the overall gain when locked by trigger.
  I also made gainx0.3 in LSC_PRCL filter bank so that it reduces the overall gain when locked by trigger.

Result for PRC in PRMI:
  For PRMI, I couldn't done dithering method because dithering takes time to measure and I could not hold PRMI locking during the measurement.
  Below is the result when reading just the DC values. Mirror angle is calibrated by oplev (elog #8221). Error bars are huge because of beam motion mainly in yaw.

PRM in pitch: PRM_PIT_20130305a.png    PRM in yaw:PRM_YAW_20130305b.png

Results for the arms:
  For the arms, I could do both in DC and dithering. Below are the results, but ITMs misalignments are not calibrated because we don't have calibrated oplev yet.
  Results for the arms can be used to verify this method because we know g-factors of the arms from mode scan.

ITMX in yaw: ITMX_YAW_20130305.png    ITMY in yaw: ITMY_YAW_20130305.png

By the way:
  I found C1:SUS-ITMY_LSC_GAIN is somehow set to be 2.895 recently. I think this should be 1.0. Maybe this is why we had actuation imbalance in ITMs(elog #8212).

 - more stable lock
 - calibrate ITM oplevs to apply this method to the arms
 - derive g-factor from these measurements
 - measure PRM angular motion spectra using calibrated oplev

  8232   Tue Mar 5 17:09:30 2013 yutaUpdateSUSoplev calibration for ITMY

[Manasa, Sendhil, Yuta]

We calibrated oplev for ITMY. Calibration factor for C1:SUS-ITMY_OL(PIT|YAW)_IN1 are;
  OLPIT: 6.29 +/- 0.11 counts/mrad
OLYAW: 5.74 +/- 0.09 counts/mrad

Note that there was ~10% of coupling between pitch and yaw.
This is large considering statistical error, but I think this is from QPD mounted rotated (by ~5 deg).

  Same as in elog #8221.

moved in y: ITMY_PIT.png      moved in x: ITMY_YAW.png

micrometer    OLPIT          OLYAW
moved in y    3.14 +/- 0.05  0.27 +/- 0.03
moved in x   -2.87 +/- 0.04  0.17 +/- 0.03    (counts/mm)

  Measured the path length of ITMY oplev returning beam was 2000 +/- 20 mm. This gives you the calibration factors above.

  ~10 % coupling between OLPIT and OLYAW can be explained by QPD rotation by ~ 5 deg, which seems not unreasonable.

  8235   Tue Mar 5 23:00:08 2013 yutaUpdateLSCYarm and PRC g-factor from misalignment measurement

I fitted intra-cavity power dependance on mirror misalignment plot with parabola to get the g-factor.

  Y arm (tangential) g = 0.44 +0.01 -0.01  (measured value before was 0.3765 +/- 0.003 elog #6938)
  PRC (sagittal)       g = 0.97 +0.01 -0.04 (expected value is 0.939 elog #8068)
  PRC (tangential)   g = 0.96 +0.02 -0.05 (expected value is 0.966 elog #8068)

Error bars are just statistical errors from the fitting. Estimated systematic error is ~0.04 (or more).
Here, I assumed PR2/PR3 to be flat to make the calculation simple. I assumed PRC to be curved PRM - flat ITM cavity, and Y arm to be curved ETMY - flat ITMY cavity.

g-factor calculation:
  Intra-cavity power decrease can be written as

dP/P = (dx/w0)**2 + (dt/a0)**2

where dx and dt are translation and tilt of the beam axis introduced by mirror misalignment. w0 is waist size and a0 is divergence angle (= lamb/(pi*w0)).

  When considering a flat-curved cavity with cavity length L, dx and dt can be expressed as;

(dx)    1  ( L*g     L ) (a2)
(  ) = --- (           )*(  )
(dt)   1-g ( -(1-g)  0 ) (a1)

using misalignments of mirrors(a1,a2). Here, mirror1 is curved, and mirror2 is flat. See Kakeru document /users/OLD/kakeru/oplev_calibration/oplev.pdf for derivation.

  So, power decrease by flat mirror misalignment can be expressed as

dP/P = pi*L/lamb * g/(1-g)/sqrt(g*(1-g)) * a2**2

  For curved mirror is

dP/P = pi*L/lamb * 1/(1-g)/sqrt(g*(1-g)) * a1**2

  We can derive g-factor by measuring dP dependance on a1/a2.

  My script lives in /opt/rtcds/caltech/c1/scripts/dither/gfactormeasurement/plotgfactor.py.
  It least fitts data with parabola (scipy.optimize.leastsq) and gets g-factor value from bisection (scipy.optimize.bisect).

  Below are the plots of fitted curves.


Systematic effect:
  [oplev calibration] We noticed QPD rotation when calibration oplevs (elog #8232). ~5 deg of rotation makes 10% of systematic error to the oplev calibration and this introduces ~0.04 of error to g-factor values. This

  [oplev linear range] Oplev linear range is ~100 urad, so this is OK.

  [assumption of flat PR2/PR3] Result here doesn't tell you g-factor of PRM itself, but some "effective g-factor" of PRM/PR2/PR3 combination. We can compare with FINESSE result.

  [intra-cavity power drift] If there's significant intra-cavity power drift during the measurement, if effects parabola fitting. We can make this affect small by sweeping the mirror alignment in both direction and take average.

By the way:
  I kept getting PRC g-factor of something like 0.999999 because I had power normalization mistake in my calculation. My script worked for Yarm because TRY is already normalized.
  Also, I was multiplying the oplev calibration factor wrong last night (see elog #8230).

  - Compare with FINESSE result.
  - Is this g-factor enough? Is this presicion enough? Calculate from mirror angluar motion.
  - More stable lock of PRMI.
  - Try dithering method to measure g-factor to check consistency and also to study systematic effect.

  8236   Tue Mar 5 23:37:11 2013 yutaUpdateSUSPRM angular motion spectra

I measured PRM angular motion spectra (in daytime today).
PRM angular motion is ~ 10 urad in RMS when undamped and ~1 urad in RMS when damped.
If PR2/PR3 angular motions are something like this, and their motion are not enhanced when PRC is locked, measured g-factor of PRC looks OK. But considering the error we have, maybe we are not OK yet. We need calculation.


  8248   Thu Mar 7 01:43:35 2013 yutaUpdateLSCcalibrated MI differential length spectra

Free swing MI differential length is 86 nm RMS and residual length when locked is 0.045 nm RMS(in-loop).
Looks very quiet. Comparison with PRMI is the next step.

Openloop transfer function:
  OLTF of simple MI lock using AS55_Q_ERR as error signal and ITMs as actuators is below.
  UGF ~ 90 Hz, phase margin ~ 40deg
  I added 16 Hz resonant gain to suppress bounce mode.

MI differential length spectra:
  Below. Calibration was done using calibrated AS55_Q_ERR and actuator response(elog #8242)

  Expected free swing is calculated using

x_free = (1+G)/G * A * fb

where G is openloop transfer function, A is actuator response, fb is feedback signal(C1:LSC_ITMX/Y_IN1) spectrum. I used A as simple pendulum with resonant frequency at 1 Hz, Q = 5. Since free swing RMS is dominated by this resonance, RMS depends on this Q assumption.

  8252   Thu Mar 7 18:12:03 2013 yutaUpdateAlignmentInput beam drift ~ 0.1 mrad/h in pitch

[Jenne, Manasa, Yuta]

We temporarily centered the beam on IPANG to see input pointing drift. From eyeball, drift was ~ 0.1 mrad/h in pitch.

What we did:

  1. Aligned TT1/TT2 and aligned input pointing to Yarm.

  2. Tweaked TT2 in pitch to center the beam on the first steering mirror of IPANG path. We still saw Yarm flash in higher order modes at this point. Before tweaking, the beam was hitting at the top edge.

  3. Centered the beam on IPANG QPD.

  4. Moved IPPOS first steering mirror because IPPOS beam was not on the mirror (off in yaw, on mirror edge). Also, IPPOS beam was coming out clipped in yaw.

  5. Centered the beam on IPPOS QPD. We put lens in the path to focus the beam on the QPD.

  6. Left input pointing untouched for 4 hours.

  7. Restored TT2 again. We tried to align Y arm with IPANG available, but it was not possible without touching TRY path and AS was also clipped.

  Below is the trend of IPANG sum, X, and Y. IPANG Y (IBQPD_Y) drifted by ~0.8 counts in 4 hours. IPANG is not calibrated yet, but Jenne used her eyeball to measure beam position shift on IPANG steering mirror. It shifted by ~2 mm. This means, input pointing drifts ~0.1 mrad/h in pitch.

  Compared with yaw, pitch drift is quite large considering beam size at ETMY(~5 mm). We can monitor input pointing drift in weekends get longer trend.

  - IPANG and IPPOS are both changed from the state before pumping.

  8254   Thu Mar 7 18:48:43 2013 yutaUpdateComputer Scripts / Programsreleasing my secret scripts

I released/updated my secret scripts to real scripts directory.
I checked they run correctly (but maybe not working correctly).

  in ./scripts/general/burtlookup.py

  It returns a value of a specified channel in the past using burt snapshots.
  Help is available.

  in ./scripts/ALS/GRtoggler.py

  Toggles green shutter until it locks TEM00.
  Help is available. Threshold setting is critical.

  in ./scripts/MC/MCbeeper.py

  Beeps when MC is unlocked.

  in ./scripts/pylibs/yutalib.py

  Python library for data loading, saving and plotting.
  I think it's well commented.

  in ./scripts/pylibs/pyezcalib.py

  Python library for ezca stuff.
  It has functions for recording and resetting default channel values in case of interrupt.

  Python scripts for PRC modescan. Not well commented. Not organized.
  See elog #8012

  Python and shell scripts for alignment work. Not well commented.
  See elog #8164

  Python scripts for oplev calibration. Not well commented.
  See elog #8221

  Python scripts for g-factor measurement. Not well commented.
  See elog #8230

  Python scripts for calibrating actuators. Not well commented.
  See elog #8242

  8255   Fri Mar 8 02:17:04 2013 yutaUpdateLSCcalibration of PRM actuator

[Manasa, Yuta]

We measured AC response of PRM actuator using PRM-ITMY cavity.
Result is

PRM:  (19.6 +/- 0.3) x 10^{-9} (Hz/f)^2 m/counts

It is almost the same as in 2011 (elog #5583). We took the same procedure as what Kiwamu did.

What we did:
  1. Aligned PRMI in usual procedure, mis-aligned ITMX and locked PRM-ITMY cavity using REFL55_Q_ERR. POP DC was about 18 when locked.

  2. Made UGF of PRM-ITMY cavity lock at 10 Hz and introduced elliptic LPF at 50 Hz(OLTF below).

  3. Measured transfer function from C1:LSC_ITMY_EXC to C1:LSC_REFL55_Q_ERR. Dividing this by ITMY actuator response(measured in elog #8242) gives calibration of REFL55_Q.

  4. Measured transfer function from C1:LSC_PRM_EXC to C1:LSC_REFL55_Q_ERR to calibrate PRM actuator.

  Calibration factor for REFL55_Q for PRM-ITMY cavity was (1.37 +/- 0.02) x 10^9 counts/m (plot below). Error is mainly from statistical error of the average.

  Measured AC response (50-200 Hz) of PRM is below.

  - Measure free-run length spectrum of PRM-ITMY cavity and compare with MICH free-run.

  8256   Fri Mar 8 03:07:19 2013 yutaUpdateLSCcalibrated PRM-ITMY length spectra

Measured free swing PRM-ITMY length was 230 nm RMS.
MI differential length was 85 nm RMS(elog #8248). This tells you that PR2, PR3 are not so noisy compared with usual suspensions.

Openloop transfer function:
  OLTF of PRM-ITMY cavity lock using REFL55_Q_ERR as error signal and PRM as actuator is below.
  UGF ~ 120 Hz, phase margin ~ 50 deg.
  Somehow, phase delay was 460 usec, which is smaller than the empirical value 550 usec.

PRM-ITMY length spectra:
  Below. Calibration was done using calibrated REFL55_Q_ERR and actuator response(elog #8255).

  8259   Fri Mar 8 15:27:42 2013 yutaUpdateGreen LockingPSL green shutter installed

[Manasa, Yuta]

Mechanical shutter for PSL green is installed right in front of PSL doubling crystal.
This is for blocking PSL green when we want to measure the power of green beam from the arms.

The shutter was previously sitting on AS table un-used. Channel name to control this shutter was C1:AUX-SPS_Shutter. This should be renamed as C1:AUX-GREEN_PSL_Shutter.

  We are going to restore both arm green in parallel to PRMI work.

  - Coarsely align IR input pointing and arms using A2L
  - Align X green
  - Install green DC PDs and cameras on PSL table

  8261   Fri Mar 8 16:05:56 2013 yutaBureaucracyGeneralaction items for PRMI / ALS-FPMI

We should focus our work both on PRMI and ALS-FPMI (elog #8250).


    - Check out ASS and A2L working -JENNE (ALS done, ASS on going elog #8229)
    - Are all whitening filters for PDs toggling correctly? -JENNE, JAMIE (POX11 was OK, elog #8246)

PRMI locking:
    - Adjust I/Q rotation angles for error signals -JENNE, YUTA (coarsely done elog #8212)
    - Adjust filters -JENNE, YUTA (coarsely done elog #8212)
    - Coil balancing for BS (and ITMs/ETMs) -YUTA (done elog #8182)
    - Calculate sensing matrix for PRMI and convert them into physical units -JENNE, JAMIE
    - Measure sensing matrix for PRMI -JENNE, MANASA
    - Measure 55 MHz modulation depth -KOJI

PRC characterization in PRMI:

    - Measure PR2 loss from flipping -MANASA (on going elog #8063)
    - Measure mode matching ratio -JENNE, YUTA
    - Measure finesse, PR gain -JENNE, YUTA (done elog #8212)
    - Calibrate PRM and/or ITM oplevs -MANASA, YUTA (done elog #8221)
    - Measure g-factor by tilting PRM or ITMs -JAMIE, YUTA (coarsely done elog #8235, use other methods to check)
    - Simulate intra-cavity power dependance on PRM tilt -JAMIE (see elog #8235)
    - Calculate expected finesse, PR gain -JENNE
    - Mode match and align aux laser from POY -ANNALISA (on going elog #8257)

    - Prepare for installation of new end tables on next vent -MANASA
    - Install green DC PDs and cameras on PSL table -JENNE, MANASA
    - Make ALS handing off to DARM/CARM LSC script -JENNE, YUTA
    - Demonstrate FPMI using ALS -JENNE, YUTA
    - Phase tracker characterization -YUTA, KOJI (bad whitening elog #8214)
    - better beatbox with whitening filters -JAMIE, KOJI

    - Update optical layout CAD after PR2 flipping -MANASA
    - IMC REFL demod phase rotation -EVAN, ANNALISA (done elog #8185)
    - Look into PMC drift -JENNE, MANASA
    - Measure RFAM contribution to error signals -YUTA
    - Look into TT2 drift -JENNE, MANASA

  8283   Wed Mar 13 08:34:33 2013 yutaUpdateLockingTWO arms TWO colors

- I took the shutter from AS table to use it for the PSL green. It was sitting near MC REFL path unused (elog #8259).

- If X green lock is not tight, maybe temporarily increasing loop gain helps. This can be done by increasing the amplitude of the frequency modulation or increasing green refl PD gain. Also, if X green beam spot is too wiggly compared with Y green, it is maybe because of air flow from the air conditioner (elog #6849). I temporarily turned it off when I did X green steering last summer.

- X green transmission on PSL table reached ~270 uW last summer (elog #6849, elog #6914). Y green transmission is now ~240 uW and ~2700 counts at maximum. So, X green transmission should reach ~3000 in counts.

- Did you have to re-align TRX path? We moved the harmonic separator on X end table horizontally to avoid IR TRX clipping before beam centering on X arm (elog #8162). I wonder what is the current situation after the beam centering.

  16827   Tue May 3 21:05:23 2022 yutaUpdateBHDAS path alignment, removing a lot of green stuff

[Tega, Yehonathan, Koji, Yuta]

We tried to align AS path this afternoon.
IMC is not aligned now after the work today crying
Green mirrors/perisocope in IMC chamber were removed since some of them was clipping the AS beam, and this changed the balance of the IMC stack and thus MC1 and MC3 alignment.

Summary of changes:
ITMY chamber
  - Rotated AS2 in roll by 90 deg to have more aperture for the transmission (photo)
  - IR beams are now centered on AS1, AS2, AS3 and AS4 (photo, photo)

BS chamber
  - Moved ASL towards -X direction for about 1/4 inch
  - Installed GRY_SM2 at the nominal position (re-used GR_SM3 from IMC chamber)

IMC chamber
  - Removed green optics GR_SM4, GR_SM3, GR_PERI2L (GR_PERI2L is now stored at Xend)
  - Removed IFI camera mirrors FIV1, FIV2 (they are now stored at Xend) (photo, photo)
  - GR_SM4 mount is now reused as GRY_SM1 (Y2-2037-0 is now mounted instead of previously mounted Y2-LW1-2050-UV-45P/AR), and GRY_SM1 is installed at the nominal position (photo)
  - Moved weights to balance the stack

OMC chamber (we don't have OMC in this chamber...)
  - We swapped AS5 and AS6 so that the nobs comes in -X direction to have more spacing between AS beam and IMC REFL beam (photo)
  - Moved weights to balance the stack

What we did:
1. Misaligned ITMX and use ITMY reflected beam to align AS path
2. Centered the IR beam on AS1 using SR2
3. Centered the IR beam on AS2 and ASL using AS1. AS2 was rotated in roll by 90 deg to have more aperture for the transmisson. cool
4. Centered the IR beam on AS3 using AS2 nobs, centered the IR beam on AS4 by rotating AS3 in yaw.
5. "AS beam" (it turned out that what we are looking was actually not the AS beam!! Some stray light) was in +X direction by 1 inch or so at AS5. Moving AS5 to center the beam would clip IMC REFL beam. So we swapped AS5 and AS6 so that the nobs comes in -X direction to have more spacing between AS beam and IMC REFL beam.
6. Balanced OMC chamber stack again using IMC REFL beam as a referece (bring the IMC REFL beam to the reference red circle on the monitor).
7. Tweaked the alignment of TT1 and TT2 to have Yarm flashing to ~0.9 in TRY. angel
8. Moved AS5 towards +X by an inch or so to center the "AS beam."
9. Moved ASL towards -X direction for about 1/4 inch and re-centered the beam by AS1 to see if the "AS beam" gets far from IMC REFL at OMC chamber, but the "AS beam" didn't move much.
10. By blocking the beam from ITMY, we found that "AS beam" was not the actual one. frown
11. Opened IMC chamber and found that AS beam is blocked by the past optics.
12. Removed old green optics and IFI camera mirrors. GR_SM4 mount and GR_SM3 were reused as mentioned above.
13. Tried to balance IMC chamber stack to recover IMC alignment. We used IMC REFL beam as a reference, but it was hard to completely bring the IMC REFL beam to the reference red circle on the monitor. It is now off by a beam diameter or so. No IMC flashing now. crying

Theoretically, balancing IMC chamber stack would recover all the IFO alignment, but maybe tough. It is maybe easier to align MC1 and MC3 to have IMC locked. Assuming input pointing to IMC is not drifted too much, we should be able to recover Yarm flashing by tweaking TT1 alignment only. However, MC3 SD OSEM is at the edge of the range. We might have to balance the stack more or tweak SD OSEM position.

  16850   Thu May 12 20:24:29 2022 yutaUpdateBHDPOX and POY investigation

[Anchal, Yuta]

We checked POX and POY RF signal chains for sanity check since Xarm cannot be locked in IR stably as opposed to Yarm.
POX beam seems to be healthy. This issue doesn't prevent us from closing the vacuum tank.

 - RF PD has SPB-10.7+ and ZFL-500NL+ attached to the RF output.
 - At the demodulation electronics rack, SMA connectors are used everywhere.
 - With Yarm flashing at ~1, RF output has ~24 mVpp right after RF PD, ~580mVpp after SPB-10.7+ and ZFL-500NL+, and ~150mVpp at right before the demodulation box.
 - There is roughly a factor of 3 loss in the cabling from POY RF PD to the demodulation rack.
 - Laser power at POY RF PD was measured to be 16 uW

 - RF PD doesn't have amplifiers attached.
 - At the demodulation electronics rack, N connector is used.
 - With Xarm flashing at ~1, RF output has ~30 mVpp right after RF PD, and ~20mVpp at right before the demodulation box.
 - Losses in the cabling from POX RF PD to the demodulation rack is small compared with that for POY.
 - Laser power at POX RF PD was measured to be 16 uW

 - POX and POY RF PDs are receiving almost the same mount of power
 - POY has larger error signal than POX because of RF amplifier, but the cable loss is high

 - There might be something in the electronics, but we can close the vacuum tanks

  16856   Mon May 16 13:22:59 2022 yutaUpdateBHDREFL and AS paths aligned at AP table

After Xarm and Yarm were aligned by Anchal et al, I aligned AS and REFL path in the AP table.
REFL path was alreasy almost perfectly aligned.

REFL path
 -REFL beam centered on the REFL camera
 -Aligned so that REFL55 and REFL33 RFPDs give maximum analog DC outputs when ITMY was misaligned to avoid MICH fringe
 -Aligned so that REFL11 give maximum C1:LSC-REFL11_I_ERR (analog DC output on REFL11 RFPD seemed to be not working)

AS path
 -AS beam centered on the AS camera. AS beam seems to be clipped at right side when you see at the viewport from -Y side.
 -Aligned so that AS55 give maximum C1:LSC-ASDC_OUT16 (analog DC output on AS55 RFPD seemed to be not working)
 -Aligned so that AS110 give maximum analog DC output

  16865   Thu May 19 18:56:08 2022 yutaUpdateBHDCurrent OSEM sensor values with all the suspensions aligned

Current OSEM sensor values with all the suspensions aligned are attached.
For 'BS','ITMX','ETMX','ITMY','ETMY','PRM','SRM','LO1','LO2', the ones out of the range [200,800] are marked, and for 'PR2','PR3','SR2','AS1','AS4', the ones out of the range [6000,24000] are marked.

  16873   Wed May 25 16:38:27 2022 yutaUpdateSUSSuspensions quick health check

[JC, Yuta]

We did a quick health check of suspesions after the pump down.

 - ITMX LRSEN is too bright (~761) and not responding to any optic motions (we knew this before the pump down)
 - ITMY ULCOIL is not working
 - LO1 LLCOIL is not working
 - Damping loops need to be retuned, especially for ETMY (too much damping), SRM, PR3 and AS4 (damping too weak)
 - MC1 sensor outputs are minus instead of plus
 - LO2 OSEMs got stuck during the pump down, but now it is free after some kicks. OSEM sensorr values almost came back (see attached)

What we did:
 1. Kicked optics with C1:SUS-{optic}_{UL,LL,UR,LR,SD}COIL_OFFSET one by one with offsets of +/- 10000 (or 100000), and checked if C1:SUS-{optic}_{UL,LL,UR,LR,SD}SEN_OUT16 move in both directions.

 2. Check if the optic damps nicely.

 3. Attached photo of the note is the result.

  16875   Wed May 25 17:34:47 2022 yutaConfigurationBHDIFO recovery - IFO alignment

IFO aligned to maximize flashings, except for GRY and LO-AS.

What we did:
 0. After recovering IMC, C1:IOO-MC_TRANS_SUM was ~1300 with C1:IOO-MC_RFPD_DCMON of ~0.11 (~10% better than what we had during vent). Xarm and Yarm was already flashing and could see the beam at AS and POP cameras.
 1. Aligned ETMX and ITMX to green X input beam to maximize C1:ALS-TRX_OUT, to ~0.19.
 2. Aligned TT2-PR3 to get C1:SUS-ETMX_TRX_OUT flashing at 0.09 at max
 3. Aligned ITMY to have nice POP blinking of MICH at POP camera
 4. Aligned ETMY-PR3 to have C1:SUS-ETMX_TRX_OUT flashing at 0.06 at max
 5. Misaligned ITMY (with +2 in C1:SUS-ITMY_PIT_COMM), and aligned PRM to have PRX (PRM-ITMX cavity) flashing at C1:LSC-ASDC_IN1 at ~20 (offset -70) at max
 6. Misaligned PRM, and aligned SRM to have SRX (SRM-ITMX cavity) flashing at C1:LSC-ASDC_IN1 at ~20 (offset -70) at max
 7. Restored all the alignment. ITMY didn't quite come back, so I need to tweak the alignement to maximize TRY flashing.

Current alignment is as attached. IR beam at AS, REFL, MCR and green beam at GTRX cameras all seem slightly to the left from monitors, but looks as it was before the pump down.yes GTRY is still clipped, but green Y locks stably. Oplevs were not so useful to recover the alignment. ETMX/Y oplevs did not drifted too much probably because we don't have in-vac steering mirrors.

 - Tweak alignment of green Y input to follow Yarm
 - Do LO-AS alignment
 - REFL DC is not receiving beam. Re-alignment necessary
 - Oplev centering
 - BHD PDs need to be replaced to lower gain PDs and need to be connected to CDS

  16877   Thu May 26 19:55:43 2022 yutaConfigurationBHDOplevs centered, BHD DCPDs are now online

[Paco, Yuta]

We have aligned the IFO (except for LO-AS and GRY), and centered all the oplevs.
We have also restored Gautam's in-air BHD DCPD setup and placed it to ITMY table.
BHD DC PD signals are now online at C1:XO4-MADC1_EPICS_CH4 and CH5. 

 Aligned the IFO following the steps in elog 40m/16875.
 When we were woking on BHD DCPDs, we lost REFL beam on camera and both arms flashing. Alignment was restored mostly with TT2 pitch.
 We centered all the oplevs after the recovery (see attached).

 1. We removed a circuit box with M2 ISS photodetector readout board from AP table, in-air BHD photodiodes from optics graveyard. (see LIGO-E2000436 and elog 40m/15493 for wiring diagram)
 2. Taken out temporary two Thorlabs PDA100A used for aligning LO-AS during the vent from ITMY table, and placed the BHD setup in ITMY table (see attached and attached).
 3. DB9 cable (15ft+10ft) was connected from M2 ISS box to anti-aliasing chassis for ADC1 of C1X04 at 1Y2 rack (see attached).
 4. +/-18V power for M2 ISS box was supplied from 1Y1 rack.
 5. BHD DCPD signals are now available at C1:XO4-MADC1_EPICS_CH4 and CH5 (see attached).

 - Tweak alignment of green Y input to follow Yarm
 - Do LO-AS alignment
 - Centering of PDs everywhere with IFO aligned
 - Update RTS model for BHD

  16880   Fri May 27 17:45:53 2022 yutaConfigurationBHDBHD camera installed, GRY aligned

[JC, Paco, Yuta]

After the IFO recovery (elog 40m/16881), we installed an analog camera for BHD fringe using a BNC cable for old SRMF camera so that we can see it from the control room.
We also aligned AS-LO using LO1,LO2 and AS4.
We then aligned GRY injection to get maximum GTRY.

Maximum TEM00s right now are
 C1:ALS-TRX_OUT_DQ ~0.20
 C1:ALS-TRY_OUT_DQ ~0.18

  16884   Wed Jun 1 11:56:28 2022 yutaUpdateALSShutter driver for GRY replaced

[JC, Yuta]

We replaced a shutter driver for GRY since it stopped working this morning.
We replaced it with a free driver which was sitting on the ITMY table.
The reverse polarity issue of C1:AUX-GREEN_Y_Shutter was fixed by switching one of the switches of the driver from N.O. to N.C.

Also, "Toggle" button was added to IFO_ALIGN.adl so that we can toggle shutters easily to find TEM00. It runs /home/controls/Git/40m/scripts/ALS/ShutterToggler.py.


The green Y shutter now works but in reverese, meaning that sending 1 to C1:AUX-GREEN_Y_Shutter closes the shutter and vice versa. This needs to be fixed.


  16886   Thu Jun 2 20:05:37 2022 yutaConfigurationPSLIMC input power recovered to 1W, some alignment works

[Paco, Yuta]

We have increased the output power from the PSL table to 951 mW (it was 96.7 mW).
IMC was recovered including WFS, and both arms are flashing nicely in IR.
We tweaked the alignment of GRX and GRY injection to align them with IR, but it was hard.
Right now IR beams are not centered on TMs. We should center them first.

What we did:
Power increase and IMC recovery
 - Replaced a beam splitter which splits the beam into IMC REFL RF PD path and WFS path from R=98% to R=10% one. Reflection goes to RF PD.
 - Put a R=98% beam splitter back into WFS path.
 - We also tried to put a window in front of IMC REFL camera to recover the arrangement in 40m wiki, but the beam reflected from the window was too weak for us to align. So, we decided not to place a window in front of the camera.
 - Attached photos are the IMC REFL path before and after the work.
 - Measured the PSL output power as Koji did in elog 40m/16672. It was measured to be 96.7+/- 0.5 mW.
 - Rotated the HWP using the Universal Motion Controller (it was not possible for us to do it from the MEDM screen). The position was changed from 73.99 deg to 36.99 deg. Output power was measured to be 951 +/- 1 mW
 - IMC locked without any other changes.
 - Changed C1:IOO-WFS_TRIGGER_THRESH_ON to 5000 (was 500). IMC WFS also worked.
 - After running MC WFS relief script, WFS DC offsets and RF offsets are adjusted following the steps in elog 40m/16835. Below are the results.

C1:IOO-WFS1_SEG1_DC.AOFF => -0.0008882080010759334
C1:IOO-WFS1_SEG2_DC.AOFF => -0.0006527877490346629
C1:IOO-WFS1_SEG3_DC.AOFF => -0.0005847311617496113
C1:IOO-WFS1_SEG4_DC.AOFF => -0.0010395992663688955
C1:IOO-WFS2_SEG1_DC.AOFF => -0.0025944841559976334
C1:IOO-WFS2_SEG2_DC.AOFF => -0.003191715502180159
C1:IOO-WFS2_SEG3_DC.AOFF => -0.0036688060499727726
C1:IOO-WFS2_SEG4_DC.AOFF => -0.004011172490815322

IOO-WFS1_I1         :  +1977.7 ->    +2250 (Significant change)
IOO-WFS1_I2         :  +3785.8 ->  +3973.2
IOO-WFS1_I3         :  +2014.2 ->  +2277.7 (Significant change)
IOO-WFS1_I4         :  -208.83 ->  +430.96 (Significant change)
IOO-WFS1_Q1         :  +2379.5 ->  +1517.4 (Significant change)
IOO-WFS1_Q2         :  +2260.4 ->  +2172.6
IOO-WFS1_Q3         :  +588.86 ->  +978.98 (Significant change)
IOO-WFS1_Q4         :  +1654.8 ->  +195.38 (Significant change)
IOO-WFS2_I1         :  -1619.9 ->  -534.25 (Significant change)
IOO-WFS2_I2         :  +1610.4 ->  +1619.8
IOO-WFS2_I3         :  +1919.6 ->  +2179.8 (Significant change)
IOO-WFS2_I4         :    +1557 ->  +1426.6
IOO-WFS2_Q1         :   -62.58 ->  +345.56 (Significant change)
IOO-WFS2_Q2         :  +777.01 ->  +805.41
IOO-WFS2_Q3         :  -6183.6 ->  -5365.8 (Significant change)
IOO-WFS2_Q4         :  +4457.2 ->  +4397.

IFO Alignment
 - Aligned both arms using IR. Both arm flashes at the following, which is consistent with the power increase.
 - With this, we tried to tweak GRX and GRY injection. The following is after the work. We could increase GTRX to 0.204 when the Xarm is aligned to green. This suggests that GRX injection is not aligned nicely yet. But the beams are also not centered on TMs. We should center them first.
 C1:ALS-TRX_OUT_DQ ~0.13
 C1:ALS-TRY_OUT_DQ ~0.07
 - GTRX and GTRY cameras are adjusted to have nicer images. In GRX path, the second and last lens before the PD and CCD was pulled ~ 1 cm behind its original position and both beams realigned. Then, on GRY path, the beam was re-centered on the first and only lens, the whole assembly pushed forward by ~ 2 cm and the beams re-centered.

 - Center the IR beam on TMs (first by our eyeballs; better to use A2L after arm locking is recovered and coils are balanced)
 - Tweak GRX and GRY injection (restore GRY PZTs?)
 - Install ETMXT camera (if it is easy)
 - Lock Xarm and Yarm (C1:LSC-TRX/Y_OUT needs to be fixed for triggering. Can we use other PDs for triggering?)
 - MICH locking (REFL and AS PDs might need to be re-aligned; they are not receiving much light)
 - RTS model for BHD needs to be updated

  16888   Fri Jun 3 15:22:51 2022 yutaUpdateLSCBoth arms locked with POY/POX, IR beam centered on TMs with ASS

[JC, Paco, Yuta]

We locked both Y and X arms with POY11 and POX11.
RFM fix (40m/16887) enabled us to use triggering using C1:LSC-TRY/X_OUT.
IR beam is now centered on TMs using ASS (for Yarm, ASS loops cannot be closed fully, so did it manually).

What we did:
 - Aligned both arms so that the beams are roughly centered at TMs using cameras.
 - Yarm lock was easy, but Xarm lock required gain tuning. Somehow, Xarm required x3 higher gain as follows, although the amplitude of POX11_I_ERR seems to be almost the same as POY11_I_ERR. I suspect it is something to do with power normalization matrix (TRX flashing is almost a double of TRY flashing).


 - Run ASS for Yarm. ASS loops cannot be closed fully using default feedback parameters. I guess this is because ITMY ULCOIL is not working (40m/16873). ASS demodulated signals were manually zero-ed by manually aligning ETMY, ITMY and PR3 (and some TT1 and TT2), except for demodulated signals related to ITMY. Beam on ITMY was centered just by using our eyes.
 - Run ASS for Xarm. It seemed to work well.
 - After this, TRX and TRY were as follows and beam positions on TMs were as attached.

C1:LSC-TRX_OUT ~0.95
C1:LSC-TRY_OUT ~ 0.58

(TRX is somehow lower than what we had yesterday... 40m/16886; TRX and TRY photodiode alignment was checked, but seems to be OK.)

 - Centered TMs and BS oplevs.

 - POX and POY demodulation phases are not fully optimized. Needs re-tuning.
 - Tweak GRX and GRY injection (restore GRY PZTs?)
 - Install ETMXT camera (if it is easy)
 - MICH locking
 - RTS model for BHD needs to be updated

  16889   Fri Jun 3 17:42:50 2022 yutaUpdateLSCMICH locks with AS55_Q

AS path at AP table as re-aligned and confirmed that MICH can be locked with AS55 Q.

What we did:
  - Aligned AS55 and AS110 paths at AP table. AS55 was not receiving enough light. AS110 was not receiving light at all.
  - Changed AS55 I and Q whitening gain from 3dB to 42dB.
  - Zero-ed the RF offsets manually. C1:LSC-AS55_Q_IN1 is having too large offset. When PSL shutter was closed, it reads 13950! Needs investigation.
  - Locked MICH with PRM mis-aligned with configurations attached.

Other Issues:
 - C1:IOO-MC_TRANS_SUM is now stuck at 14009. MC auto locker doesn't work correctly. FIX ME!

  16894   Mon Jun 6 21:01:22 2022 yutaUpdateIMCMC1 OSEM sensor sign flipped, MC1/2/3 free swinging overnight for inmat diagonalization

[Tomislav Andric, Rana, Yuta]

We put -1 to MC1 OSEM sensor gains and re-tuned MC1 damping.
We also kicked MC1, MC2, MC3 tonight for input matrix diagonalization.

MC1 damping investigations:
 We put -1 to MC1 OSEM sensor gains so that UL/UR/LR/LL/SDSEN_OUT will be positive like other optics.
 OSEM damping filter gains were adjusted.
 We have also checked if having +1 for all UL/UR/LR/LL/SDCOIL_GAIN is correct or not. It has been like this at least for the past year.
 It should be -1 for UR and LL to account for magnets, but if we did put -1 or them, kick in C1:SUS-MC1_PIT_OFFSET mostly gave yaw kick and kick in C1:SUS-MC1_YAW_OFFSET mostly give pitch kick.
 So, we reverted them to be +1.

Input matrix diagonalization:
 We also kicked MC1, MC2, MC3 tonight input matrix diagonalization.
 Kick was done manually at the following times local.
  - MC1 20:08 June 6th, 2022
  - MC2 20:24 June 6th, 2022
  - MC3 20:21 June 6th, 2022
 We will leave watchdogs shutdown to free swing overnight (damping loops are "on").
 This will help get better angular sensor from OSEMs to calibrate WFS signals.

 - Investigate why MC1 coils gains have +1 for all
 - Calculate input matrix. Make sure SUSPOS/PIT/YAW/SIDE_IN will be in the units of um or urad.

 - Add filter ramp time of 1sec for all by default
 - Make null stream channel from input matrix for diagnostics

  16896   Tue Jun 7 17:26:21 2022 yutaUpdateSUSITMY ULCOIL mystery not solved

[Paco, Yuta]

We investigated the ITMY ULCOIL issue (40m/16873).
ULSEN is sensing the optic motion but ULCOIL cannot move the optic.
We confirmed that the coil input is there upto satellite amplifier output.
We also checked that ULCOIL have 3.3 mH and 16 Ohms, which are consistent with other coils.
Mystery remains...
We need to investigate ITMY ULCOIL in the next vent.

What we did:
 - Checked again that C1:SUS-ITMY_ULCOIL_OFFSET does not kick ITMY using OSEM sensor signals and oplev signals. ULSEN moves when ITMY is kicked by other coils.
 - Checked that kick gives voltage changes at coil driver and satellite amplifier output. We unplugged J1 DB25 cable from the feedthru flange and checked the signals sent to coil with oscilloscope.
 - Measured inductance (using BK PRECISION LCR meter) and resistance (using Fluke) of coils for ITMY. Below is the result. UL coil seems to be consistent with other coils. (It seems like BK PRECISION one wil give wrong resistance if the dial is set to the resistance value which is too low compared with the one you want to measure. If you want to measure 16Ω, set the dial to larger than 20Ω, not 2Ω)

Feedthru connector: ITMY1
Pin 3-15 / R = 16.3Ω / L = 3.32 mH (UL)
Pin 7-19 / R = 16.4Ω / L = 3.30 mH (UR)
Pin11-23 / R = 16.2Ω / L = 3.31 mH (LL)

Feedthru connector: ITMY2
Pin 3-15 / N/A
Pin 7-19 / R = 16.3Ω / L = 3.30 mH (SD)
Pin11-23 / R = 16.4Ω / L = 3.33 mH (LR)

 - UL is the only short OSEM in ITMY OSEMs.
 - ITMY have dumbells for magnets.
 - If UL magnet is off, ULSEN would not work. Something not magnetic is working for shadow sensing for UL? Dumbells?
 - ULSEN just sensing some coupling from other OSEMs?

  16898   Tue Jun 7 19:13:12 2022 yutaUpdateSUSAgreement on suspension damping loop polarity conventions

Anchal, Paco and I agreed to follow the polarity conventions below for suspension damping loops.
Some of the polarity/gains were changed to homogenize all the suspensions to the convention.
All the suspensions are homogenized except for MC1 (which have all - in sensor inputs and all - in coil outputs) and AS1 (SDCOIL_GAIN have the same sign as LL).

*SEN_GAIN to be +1
INMATRIX to be the following, and calibrated so that SUSPOS/SIDE_IN will be um and SUSPIT/YAW_IN1 will be urad (calibration to be done later)
+ + + + *
+ + - - *
+ - - + *
* * * * +
SUS*_GAINS to be +

TO_COIL gains to be the following
+1 +1 +1  *
+1 +1 -1  *
+1 -1 +1  *
+1 -1 -1  *
 *  *  * +4
*COIL_GAIN to be the following or flipped one so that SUS*_GAINS will be +

To do this, the following changes were made

For BS, ITMX, ITMY, PRM, SRM, ETMX, ETMY, MC1, MC2 and MC3 ("old" suspensions), TO_COIL_5_4_GAIN (for side) is changed from +1 to +4 and SUSSIDE_GAINs are divided by 4 accordingly.
For ETMX, the sign of SUSSIDE_GAIN is flipped to +, and SDCOIL_GAIN to be -1 (it was +1).
For MC1, *SEN_GAINs are - (not following the convension; see 40m/16894). The sign of INMATRIX_4_5 (for side) is flipped to +, SUSPOS/PIT/YAW_GAIN are flipped to +, and *COIL_GAIN are flipped to - (not following the convension). IMC WFS output matrix components for MC1 were also flipped. 

  16903   Wed Jun 8 18:16:20 2022 yutaUpdateSUSITMY ULCOIL mystery: Coil driver swap test

To see if the ULCOIL channel of the ITMY coil driver is working or not, I swapped ITMY coil driver and ITMX coil driver by swapping DB15 cable (see Attachment #2).

With this swap, I confirmed that ITMX can be kicked with C1:SUS-ITMY_ULCOIL_OFFSET, but ITMY cannot be kicked with C1:SUS-ITMX_ULCOIL_OFFSET (see Attachment #1).

This means that the issue is not the in-air electronics.
Mystery remains again...
We need to investigate ITMY ULCOIL in the next vent.

I revereted the swap and confirmed that damping loops work fine again.

  16905   Fri Jun 10 13:02:14 2022 yutaUpdateSUSITMY ULCOIL mystery: Coil driver swap test

ITMY ULCOIL was measured to have ~3.3 mH as measured from the flange. RTFE 40m/16896 .


what was the result of the inductance measurement? should be ~3.3 mH as measured from the flannge or cable that goes to the flange from sat amp.



  16907   Fri Jun 10 15:02:04 2022 yutaUpdateSUSServo gain sign flipped for MC1 WFS relief

The servo gain for MC1 in /opt/rtcds/caltech/c1/Git/40m/scripts/MC/WFS/reliefWFS was flipped to account for COIL_GAIN flip done in 40m/16898.
The reliefWFS script now works fine.

ezcaservo -r 'C1:SUS-MC2_ASCPIT_OUT16' -g ${g} -t ${ts} C1:SUS-MC2_PIT_COMM & 
ezcaservo -r 'C1:SUS-MC2_ASCYAW_OUT16' -g ${g} -t ${ts} C1:SUS-MC2_YAW_COMM & 
ezcaservo -r 'C1:SUS-MC1_ASCPIT_OUT16' -g -${g} -t ${ts} C1:SUS-MC1_PIT_COMM &  
ezcaservo -r 'C1:SUS-MC1_ASCYAW_OUT16' -g -${g} -t ${ts} C1:SUS-MC1_YAW_COMM & 
ezcaservo -r 'C1:SUS-MC3_ASCPIT_OUT16' -g ${g} -t ${ts} C1:SUS-MC3_PIT_COMM & 
ezcaservo -r 'C1:SUS-MC3_ASCYAW_OUT16' -g ${g} -t ${ts} C1:SUS-MC3_YAW_COMM & 

  16909   Fri Jun 10 20:11:46 2022 yutaUpdateASCYarm ASS re-tuning in progress

[Anchal, Yuta]

We tried to re-tune Yarm ASS today. It cannot be fully closed as of now. I think we need to play with signs.

 - We want to make sure Yarm ASS work with current ITMY coil matrix (40m/16899).
 - ASS makes the beam positions on test masses to be the same every day.

What we did:
 - Adjusted A2L paths of C1:ASS-YARM_OUT_MTRX based on cavity geometry. For the paths to maximize the transmission using TT1 and TT2, we just assumed they are correctly calculated by someone in the past.
 - Adjusted OSC_CLKGAINs so that ITMY and ETMY will be shaken in the same amplitude in terms of radians. The ratio of the excitation was determined to take into account for the oscillator frequency difference between DOFs.
 - Checked the time constant of A2L paths by turning on A2L paths only, and checked that of max-transmission paths by turining on them only.
 - Adjusted DEMOD_SIG_GAINs so that their time constants will be roughly the same, with C1:ASS-YARM_SEN_MTRX fully identity matrix and all servo GAINs to be +1.
 - Re-tuned DEMOD_PHASEs to minimize Q signal. C1:ASS-YARM_ITM_PIT_L_DEMOD_PHASE and C1:ASS-YARM_ITM_YAW_T_DEMOD_PHASE were re-tuned within +/- 5 deg.
 - These changes are recorded in /opt/rtcds/caltech/c1/Git/40m/scripts/ASS/ASS_DITHER_ON.snap now.

 - A2L loops seems to be working, but max-transmission paths seems to diverge at some point. I think we need to play with the signs/gains of max-transmission paths for C1:ASS-YARM_OUT_MTRX.
 - Attached is the current configuration we achieved so far.

  16910   Fri Jun 10 21:10:01 2022 yutaUpdateSUSITMY ULCOIL mystery: Coil driver swap test

We checked the photos we have, but we didn't have the photos which show ULCOIL situation clearly.

Free swing of ITMY (and others) will be done this weekend to see the OSEM spectra and resonant frequencies.

  16911   Mon Jun 13 20:26:09 2022 yutaUpdateASCYarm ASS re-tuning in progress -part 2-

[Anchal, Yuta]

We are still in the progress of re-commissioning Yarm ASS.
Today, we tried to adjust output matrix by measuring the sensing matrix at DC.
Turning on yaw loops kind of works, but pitch does not. It seems like there is too much coupling in pitch to yaw.
We might need to adjust the coil output matrix of ITMY and ETMY to go further, and/or try measuring the sensing matrix including pitch - yaw coupling.

What we did:
 - Confirmed that turning on TT1 and TT2 loops (max-transmission loops) work fine. When we intentionally misalign TT1/2, the ASS loops correct it. So, we moved on to measure the sensing matrix of A2L paths, instead of using theoretical matrix caluclated from cavity geometry we used last week (40m/16909).
 - Instead of +/-1's, we put +/-2's in the ITMY coil output matrix to balance the actuation between ETMY and ITMY to take into account that ITMY is now using only two coils for actuating pitch and yaw (40m/16899).
 - Measured the change in C1:ASS-YARM_(E|I)TM_(PIT|YAW)_L_DEMOD_I_OUT16 error signals when offset was added to C1:SUS-(E|I)TMY_ASC(PIT|YAW)_OFFSET. We assumed pitch-yaw coupling is small enough here. Below was the result.

                            ETM PIT error  ITM PIT error
ETM PIT OFFSET of +100cnts: -3.0cnts       -2.99cnts
ITM PIT OFFSET of +100cnts
: -11.94cnts      -5.38cnts

                            ETM PIT error  ITM PIT error
ETM YAW OFFSET of +100cnts:
-3.42cnts      -16.93cnts
ITM YAW OFFSET of +10 cnts: +1.41cnts      +0.543cnts

 - Inverted the matrix to get A2L part of C1:ASS-YARM_OUT_MTRX. Attachment #1 is the current configuration so far.
 - With this, we could close all yaw loops when pitch loops were not on. But vise versa didn't work.
 - Anyway, we aligned the IFO by centering the beams on test masses by our eyes and centered all the oplevs (Attachment #2).

 - Do coil balancing to reduce pitch-yaw coupling
 - Measure sensing matrix also for pitch-yaw coupling
 - Xarm ASS is also not working now. We need to do similar steps also for Xarm

  16914   Tue Jun 14 19:34:06 2022 yutaUpdateSUSResonant frequency identification from the free swing test

[JC, Anchal, Yuta]

We are working on resonant frequency idendification from the free swing test done last weekend.
Table below is the resonant frequencies identified, and attached are the plots of peak identification for some of our new suspensions.
To identify the resonant frequencies, the kicks were done in each degrees of freedom so that we can assume, for example, SUSPOS will be mostly excited when kicked in POS and the heighest peak is at the POS resonant frequency.
For PR3, AS1 and ETMY, the resonant frequency idendification needs to be done in the order of POS, PIT, YAW, SIDE and identified frequencies need to be removed when finding a peak.
Other than that, the identification was done without any prior assumptions on the suspensions.
For ITMY, ETMY, PR2, PR3, AS1, AS4, yaw has lower resonant frequencies than pitch, as opposed to other suspensions.
For LO1, POS and PIT frequencies might be swapped because LLCOIL is not working (40m/16898) and POS/PIT kicks both might be excited SUSPOS/PIT.
LO1 coil output matrix was temporarily modified so that we use only two coils for POS/PIT/YAW excitation (Attachment #7), as we did for ITMY (40m/16899).

The scripts for the free swinging test and analysis live in /Git/40m/scripts/SUS/InMatCalc

     POS    PIT    YAW    SIDE
BS   0.990  0.748  0.794  0.959 
ITMY 0.987  0.739  0.634  0.948 fPIT > fYAW
ETMY 0.979  0.816  0.649  0.954 fPIT > fYAW
ITMX 0.978  0.586  0.758  0.959 
ETMX 0.962  0.725  0.847  1.000 
PRM  0.939  0.541  0.742  0.990 
PR3  1.019  0.885  0.751  0.989 fPIT > fYAW
PR2  0.996  0.816  0.724  0.999 fPIT > fYAW
SRM  0.969  0.533  0.815  0.985 
SR2  0.978  0.720  0.776  0.997 
LO1  0.926  1.011  0.669  0.993 POS AND PIT MIGHT BE SWAPPED
LO2  0.964  0.998  0.995  0.990 WRONG DUE TO STUCK (40m/16913)
AS1  1.028  0.832  0.668  0.988 fPIT > fYAW
AS4  1.015  0.800  0.659  0.991 fPIT > fYAW
MC1  0.967  0.678  0.797  0.995 
MC2  0.968  0.748  0.815  0.990 
MC3  0.978  0.770  0.841  0.969 
  16919   Wed Jun 15 15:45:37 2022 yutaUpdateSUSLO1 LLCOIL now working, it was loose connection

We tracked the issue of LO1 LLCOIL not actuating LO1, and found that the DB9 cable from the coil driver to the sat amp was loose.
I tightened the screws and now it is working.
Never ever connect cables without screwing the connectors tightly! angryno

What I did:
 - Measured the resistance and the inductance of each coil with BK PRECISION LCR meter, as I did for ITMY (Attachment #1, 40m/16896). The result is the following and it shows that LLCOIL is there.

Feedthru connector: LO1 1
Pin 3-15 / R = 16.0Ω / L = 3.27 mH (UL)
Pin 7-19 / R = 15.8Ω / L = 3.27 mH (UR)
Pin11-23 / R = 15.7Ω / L = 3.27 mH (LL)

Feedthru connector: LO1 2
Pin 3-15 / N/A
Pin 7-19 / R = 15.6Ω / L = 3.22 mH (SD)
Pin11-23 / R = 15.9Ω / L = 3.30 mH (LR)

 - Swapped the DB25 cable which goes to the feedthru LO1 1 and feedthru LO1 2. LLCOIL could be drived from LR coil driver and LRCOIL could not be drived from LL coil driver. SD and UR worked fine with the swap. This means that there is something wrong with the LL driving.
 - Went to see the rack which have coil drivers and sat amp for LO1, and immediately found that the DB9 cable was loose (Attachment #2). Tightened them and the issue was fixed.
 - C1:SUS-LO1_TO_COIL matrix gains were reverted to default values (Attachment #3).

  16920   Wed Jun 15 17:03:17 2022 yutaUpdateSUSITMY ULCOIL issue solved, loose connection in sat amp box

[Anchal, Yuta]

We fixed the issue of ITMY ULCOIL not driving ITMY by replacing one of the 64pin ribbon cable in the satellite amplifier box.
We thought the coil driver and the sat amp box are OK by checking the voltage change at the output of the sat amp box by giving an offset to UL coil driver, but it was not giving a current change, probably due to too much contact resistance in the cables.
It was sneaky because it was not completely disconnected.

All the coils for our suspensions are now working!

What we did:
 - Using breakout boards, the output current of sat amp box was measured using FLUKE multimeter. It turned out that UL is not giving measurable current. We also confirmed that UR coil driver can drive UL by re-directing the current from UR coil driver to UL. This means that the UL magnet was not de-magnetized!
 - Measured the coil resistance from at the coil driver output and found that UL coil seen from there has too high resistance which cannot be measured with the multimeter, whereas UR coil was measured to be ~30 Ohms.
 - Went back to the feedthru and measured the resistance of UL coil. Upto the output of the Satellite Amp Terimator, the resistance was measured to be ~16 Ohms, but not at the input of the Satellite Amp Terimator (Attachment #1,2).
 - It turned out that #16 pin of 64pin ribbon cable in between the Satellite Amp Terimator (LIGO-D990021) and the Satellite Amp board (LIGO-D961289) at the Satellite Amp Terimator side was not good (Attachment #3).
 - Replaced the cable and confirmed that ULCOIL can kick ITMY (Attachment #4).
 - C1:SUS-ITMY_TO_COIL matrix was reverted to default values.

 - We might have to re-commission Yarm ASS again since pitch-yaw coupling have changed. -> EDIT: Checked that it works (except for ITM PIT L), including offloading offsets (writeASS_offsets.py), 18:30 local.
 - Now that LO1 LLCOIL issue is solved and LO2 stuck is solved, we should do the free swing test again to identify the resonant frequencies.
 - OSEM sensor diagonalization (input matrix), coil balancing (and F2A)

  16922   Thu Jun 16 15:29:03 2022 yutaUpdatePSLPMC input beam aligned again, IMC

[Paco, Tomislav, Yuta]

Somehow, when we were trying to measure WFS open loop transfer functions, PMC unlocked many times for the past two hours and PMC transmission got low.
PMC iput beam was aligned again, and IMC WFS DC offsets and RF offsets were adjusted.
PMC transmission is now C1:PSL-PMC_PMCTRANSPD~0.75, and IMC transmission is C1:IOO-MC_TRANS_SUM~1.4e4.
Actually, IMC transmission once reached 1.5e4 at 06-16-2022 20:01 UTC with PMC transmission of 0.75 (see Attached). There might be a better alignment.

  16929   Fri Jun 17 16:22:21 2022 yutaUpdateLSCActuator calibration of BS. ITMX, ITMY, updated MICH displacement spectra from c1cal

Following what we have done in 2013 (40m/8242), actuator calibration was done using MICH.

AS55_Q in MICH : 9.74e8 counts/m
BS   : 26.08e-9 /f^2 m/counts
ITMX : 5.29e-9 /f^2 m/counts
ITMY : 4.74e-9 /f^2 m/counts

Optical gain is 25% lower than the measurement in June 6 (40m/16892), probably because our estimate was too rough then and also we now have ~15% lower IMC transmission.
Actuator gains are 2-30% higher than the measurement in 2013.

MICH error signal calibration:
 C1:LSC-AS55_Q_ERR was calibrated by taking data with C1:LSC-ASDC_OUT, when Michelson was aligned and free swinging (Attachment #1).
 AS55_Q and ASDC were X-Y plotted and fitted with ellipse to get an amplitude of AS55_Q to be 82.51 counts (Attachment #2).
 4*pi*A/lambda gives you 9.74e8 counts/m, where meters are in terms of difference between BS to ITMX length and BS to ITMY length.
 Jupyter notebook: https://git.ligo.org/40m/scripts/-/blob/main/CAL/MICH/MICHOpticalGainCalibration.ipynb

Openloop transfer function for actuator calibration:
 C1:LSC-MICH_GAIN was lowered to -1 (instead of -6), and some of filters are turned off to make the MICH UGF to be ~10.
 Also, ellip("LowPass",4,1,40,50) was added to C1:LSC-MICH_A filter bank to cut the feedback above 50 Hz, so that the loop does not suppress the measurement.
 The configuration is in Attachment #3.

Actuator calibration of BS, ITMX, ITMY:
 With this MICH OLG, transfer functions from C1:LSC-BS,ITMX,ITMY_EXC to C1:LSC-AS55_Q_ERR were measured.
 AS55_Q was calibrated to meters using the calibration factor above, and fitted the transfer function with 1/f^2 in 70-150 Hz range to get the actuator efficiency mentioned above (Attachement #4).
 Thus, meters in this calibration is in terms of ITM POS motion (not in BS POS motion).
 Jupyter notebook: https://git.ligo.org/40m/scripts/-/blob/main/CAL/MICH/MICHActuatorCalibration.ipynb

MICH displacement noise:
 Measured values were added to c1cal model as follows.
  C1:CAL-MICH_CINV FM2: 1/9.74e8 = 1.03e-9
  C1:CAL-MICH_A FM2: 2.608e-8 (it was 2.07e-8 from 2013!)
  C1:CAL-MICH_A_GAIN = 0.5 to take into account of C1:LSC-OUTPUT_MTRX_8_2=0.5 in the LSC output matrix for BS
 Spectrum of C1:CAL-MICH_W_OUT (now calibrated in nm) with configuration in Attachment #5 was taken.
 Attachement #6 is the result. I also took the spectrum with PSL shutter off to measure the sensing noise. The sensing noise limits our sensitivity above ~40 Hz at 5e-11 m/rtHz.

  16932   Tue Jun 21 14:17:50 2022 yutaConfigurationBHDBHD DCPDs re-routed to c1sus2

After discussing with Anchal, we decided to route BHD related PD signals directly to ADC of c1sus2, which handles our new suspensions including LO1, LO2, AS1, AS4, so that we can control them directly.
BHD related PD signals will be sent to c1lsc for DARM control.

Re-cabling was done, and now they are online at C1:X07-MADC1_EPICS_CH16 (DC PD A) and CH17 (DC PD B) with 15ft DB9 cable.
Here, DC PD A is the transmission of BHD BS for AS beam, and DC PD B is the reflection of BHD BS for AS beam (see attached photo).

  16935   Tue Jun 21 21:17:16 2022 yutaUpdateBHDRTS models for BHD added but PCIE error remaining

[Anchal, Yuta]

RTS models for BHD homodyne phase control (c1hpc) and angular control (c1bac) are created and added to c1sus2.
c1su2 and c1lsc models were modified accordingly.
We still have issues with IPC PCIE connection sending DCPD A and B signals to c1lsc and DC error 0x2000 in c1su2 model.

c1hpc (host: c1sus2) Attachment #1
 This model is for homodyne phase control.
 It can dither LO1, LO2, AS1, AS4 in POS and demodulate mixture of DCPD A/B signals for the phase control to feedback to those optics.
 It also sends DCPD A/B signals to c1lsc via cdsIPCx_PCIE.
 Dither and controls signals are sent to the optics via cdsIPCx_SHMEM.

c1bac (host: c1sus2)
 This model is for BHD angular control.
 It is basically the same as c1hpc, but it is for PIT and YAW dithering of LO1, LO2, AS1, AS4.

c1su2 (host: c1su2) Attachment #2
 LSC and ASCPIT/YAW feedback signals from c1hpc and c1bac via shared memory were added to send them to corresponding optics.
 Somehow Mux/Demux didn't work to send SHMEM signals inside the subsystem in the Simulink model (this works for ADC, but probably not for IPC stuff?), and we had hard time make-install-ing this model.

c1lsc (host: c1lsc) Attachment #3
 DCPD A/B signals from c1hpc via PCIE were added for our new error signals for LSC.

Starting and restarting the models
 After having some troubles make-install-ing modified models (be careful of goto and from tags!), we stopped all the models in c1sus, c1ioo, c1lsc, c1sus2 and started all of them, including new c1hpc and c1bac models.
 This somehow created RFM errors in c1scx and c1scy.
 So, we proceeded to do the same step we did in 40m/16887 and 40m/15646, now including c1sus2 for the restart.
 Initial attempt made c1lsc, c1sus, c1ioo mostly red, so scripts/cds/rebootC1LSC.sh was run again on pianosa.
 RFM issues for c1scx and c1scy were solved.
 Shared memory within c1sus2 seems to be working, but sending DCPD A/B signals from c1hpc to c1lsc is not working (see Attachement #4).

 - Fix C1:HPC-LSC_DCPC_A/B issue
 - Make/modify MEDM screens

  16940   Wed Jun 22 18:55:31 2022 yutaUpdateLSCDaily alignment work; POY trouble solved

[Koji, Yuta]

I found that Yarm cannot be locked today. Both POY11 and POYDC were not there when Yarm was aligned, and ITMY needed to be highly misaligned to get POYDC.
POY beam also could not be found at ITMY table.
Koji suggested to use AS55 instead to lock Yarm. We did it (AS55_I_ERR, C1:LSC-YARM_GAIN=-0.002) and manually ASS-ed to get Yarm aligned (ASS with AS55 somehow didn't work).
After that, we checked ITMY table and found that POY beam was clipped at an iris which was closed!
I opened it and now Yarm locks with POY11 again. ASS works.
PMC was also aligned.


  16949   Mon Jun 27 12:32:45 2022 yutaUpdateIOOWFS issues fixed

[Anchal, Yuta]

We found that MC1 local damping loop signs were revereted to the state before our standardization on June 7th (40m/16898), but the WFS output matrix was not reverted.
This caused the sign flip in the feedback to MC1, which caused the IMC WFS issue.
This probably happened when we were restarting the models after RTS modeling (40m/16935). We might have used wrong snap files for burt-restoring.

We went back to the snapshot taken at 09:19 June 21, 2022 and now the IMC WFS is working,

  16952   Mon Jun 27 18:54:27 2022 yutaUpdateLSCModulation depths measurement using Yarm cavity scan

[Yehonathan, Yuta]
EDITED by YM on 22:11 June 27, 2022 to correct for a factor of two in the modulation index

Since we have measured optical gain in MICH to be an order of magnitude less compared with Yehonathan's FINESSE model (40m/16923), we measured the power at AS55 RF PD, and measured the modulation depths using Yarm cavity scan.
We found that 50/50 beam splitter which splits AS55 path into RF PD and RF QPD was not included in the FINESSE model. Measured modulation index were as follows:

TEM00 peak height: 0.6226 +/- 0.0237
RF11 peak height: 0.0067 +/- 0.0007
RF55 peak height: 0.0081 +/- 0.0014
RF11 modulation index: 0.208 +/- 0.012
RF55 modulation index: 0.229 +/- 0.020
RF11 modulation index: 0.104 +/- 0.006
RF55 modulation index: 0.114 +/- 0.010

Here, modulation depth m is defined in E=E_0*exp(i*(w*t+m*sin(w_m*t))), and m m/2 equals to square of the intensity ratio between sidebands and TEM00.

Power measurement at AS55 RF PD:
 - ITMY and ITMX single bounce reflection was measured to be 50-60 uW at the front of AS55 RFPD.
 - In the FINESSE model, it was expected to be ~110 uW with 0.8 W input to PRM (0.8 W * 5%(PRM) * 50%(BS) * 50%(BS) * 10%(SRM) * 10%(AS2) gives 100 uW)
 - In AP table, AS55 beam was split into two paths with 50/50 beam splitter, one for AS55 RF PD and one for AS WFS and AS110. This will be included in the FINESSE model.

Modulation depth measurement using Yarm cavity scan:
 - Aligned Yarm using ASS, and unlocked Yarm to get the 2sec scan data of C1:LSC-TRY_OUT_DQ, C1:LSC-POY11_I_ERR_DQ, C1:LSC-AS55_I_ERR_DQ.
 - TRY data was used to get TEM00 peak heights
 - POY11/AS55 data was used to find RF11/RF55 sideband peaks, and height was measured at TRY (see attached).
 - If we define m to be E=E_0*exp(i*(w*t+m*sin(w_m*t))), the amplitude of TEM00 I_00 is proportional to J_0(m) and the amplitude of upper/lower sideband I_f1 is proportional to J_1(m), where J_n(m) is the bessel function of the first kind.
 - m can be calculated using 2*sqrt(I_f1 / I_00).
 - Results were shown above. Error is calculated from the standard deviation of multiple measurements with multiple peaks,
 - The code for doing this lives in https://git.ligo.org/40m/measurements/-/blob/main/LSC/YARM/modulationIndex.ipynb

 - Power at AS55 account for the factor of 2, In the FINESSE model, modulation index of 0.3 was used (could be m=0.3/2 or m=0.3; needs check). These combined can explain a factor of 3 at least (or 6).
 - Gautam's measurement in Jan 2021 (40m/15769) gives almost double modulation index, but I'm not sure what is the definition Gautam used. It agrees with Gautam's measurement in Jan 2021.

  16954   Tue Jun 28 14:24:23 2022 yutaUpdateBHDBHD DC PD signals now also sent to c1lsc to circumvent IPC error

[JC, Yuta]

To circumvent IPC error sending BHD DC PD signals from c1sus2 to c1lsc, DB9 cable from BHD DC PD box sent to c1sus2 is now split and sent also to c1lsc.
They are now available in both

c1sus2 ADC1
C1:X07-MADC1_EPICS_CH16 (DC PD A) and CH17 (DC PD B)

c1lsc ADC1
C1:X04-MADC1_EPICS_CH4 (DC PD A) and CH5 (DC PD B)

 - Add battery powered SR560 to decouple c1sus2 and c1lsc to avoid the ground loop

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