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  40m Log, Page 326 of 327  Not logged in ELOG logo
ID Date Authorup Type Category Subject
  8080   Wed Feb 13 19:41:07 2013 yutaSummaryGeneralpossible explanations to oval REFL beam

We checked that REFL beam is already oval in the vacuum. We also centered in-air optics, including lens, in the REFL path, but REFL still looks bad.

By using IR card in vacuum, PRM reflected beam looks OK at MMTs and at the back face of the Faraday. But the beam looks bad after the output aperture of the Faraday.

  8082   Thu Feb 14 00:10:12 2013 yutaSummaryAlignmentREFL is not clipped

Let's wait for astigmatism calculation.
In either case(clipping or astigmatism), it takes time to fix it. And we don't need to fix it because we can still get LSC signal from REFL.
So why don't we start aligning input TTs and PRMI tomorrow morning.

Take the same alignment procedure we did yesterday, but we should better check REFL more carefully during the alingment. Also, use X arm (ETMX camera) to align BS. We also have to fix AS steering mirrors in vacuum. I don't think it is a good idea to touch PR2 this time, because we don't want to destroy sensitive PR2 posture.


Calculations need to be done in in-air PRMI work:
  1. Explanation for REFL astigmatism by input TTs (Do we have TT RoCs?).
  2. Expected g-factor of PRC (DONE - elog #8068)
  3. What's the g-factor requirement(upper limit)?
    Can we make intra-cavity power fluctuation requirement and then use PRM/2/3 angular motion to break down it into g-factor requirement?
    But I think if we can lock PRMI for 2 hours, it's ok, maybe.
  4. How to measure the g-factor?
    To use tilt-and-measure-power-reduction method, we need to know RoC of the mirror you tilted. If we can prove that measured g-factor is smaller than the requirement, it's nice. We can calculate required error for the g-factor measurement.

  8091   Fri Feb 15 20:07:28 2013 yutaUpdateAlignmentPOP path set up but AS55 is broken

[Manasa, Yuta]

We set up POP camera and POPDC PD, and centered REFL PDs.
We also tried to center AS55 PD, but AS55 seems to be broken.

What we did:
 1. POP path alignment:
   Shot green laser pointer from ITMX table at where POPDC PD was sitting and centered green beam at optics in the POP path. Steered POPM1/M2 mirrors in the ITMX chamber to make green laser overlap with the PRM-PR2 beam as far as I can reach from ITMX chamber. We removed some ND filters and a BS for attenuating POP beam because POP power was somehow so low. Currently, POP is pick-off of the beam which goes from PRM to PR2.

 2. POP camera and PD:
   We first used camera to find the beam at where POPDC PD was sitting because it is much easier to find focused beam. Put an iris in front of the camera, and put POP DC behind it. Steered a mirror in front of PD to maximize DC output.

 3. REFL PDs:
   Steered mirrors in the REFL path to center the beam and maximized DC outputs, as usual.

 4. AS55:
   AS55 was not responding very much to the flashlight nor AS beam. C1:LSC-ASDC_OUT looked funny. By swapping the ribbon cables of AS55, REFL55, and REFL165, I confirmed that AS55 PD itself is broken. Not the ribbon cable nor PD circuit at LSC rack. I don't know what happened. AS55 was working on Feb 8 (elog #8030).

Result:
  We aligned PRMI coarsely. POP(right above) looks much better than before. REFL (left below) still looks elliptic, but ellipticity differs with the position on the camera. Some astigmatism is happening somewhere. AS (right below) looks pretty nice with MI aligned.


Next:
  1. Fix AS55? Or replace it with POP55 PD, which is currently unused.
  2. Confirm we are getting the right error signals or not, and lock PRMI.

  8092   Fri Feb 15 21:22:29 2013 yutaUpdateElectronicsAS55 replaced with POP55 PD

I temporarily replaced AS55 PD with PD labeled "POP55(POY55)".
I think POP55 is working because I could lock MI with this PD using AS55_Q_ERR as an error signal. I rotated I/Q phase (C1:LSC-AS55_PHASE_R) to 70 deg by minimizing ASDC during MI lock.

POP55 PD was freely sitting on the ITMX table.
I will leave AS55 PD at free space of the AP table. Someone, please look into it.

  8093   Sat Feb 16 17:27:26 2013 yutaUpdateSUSPRM coil balanced

PRM coil gains and f2a filters are adjusted for PRMI work.
It seems like UR/LL coil gains were ~10 % larger than others, and f2a filters changed by few %.

What I did:
  1. Tried to lock PRMI but when I turn on PRCL lock, PRM reflection looked like it tends to go up and left in REFL camera (last night).

  2. So, I set up PRM oplev back, by steering PRM oplev mirrors on the BS table (last night).

  3. Turned PRM oplev sero on, f2a filters off, and ran

> /opt/rtcds/caltech/c1/scripts/SUS/F2P_LOCKIN.py -o PRM

  I had to fix F2P_LOCKIN.py because it assumed some OUTPUT buttons in LOCKIN1 filters to be ON.
  Also, I had to restore filters in LOCKIN1 (8.5 Hz bandpass filter etc.) because their names were changed. To do this, I copied filters needed from /opt/rtcds/caltech/c1/chans/filter_archive/c1sus/C1SUS_110916_162512.txt, renamed LOCKIN1_(I|Q|SIG) with LOCKIN1_DEMOD_(I|Q|SIG), and pasted to the current filter bank file. I checked that they look OK with foton after editing the file.

  This measurement takes about 30 minutes. I ran several times to check consistency. There was ~ 0.1 % standard deviation for the measurement results.

  4. By putting measured coupling coefficients and PRM pendulum frequency (f0=0.993 Hz) to /opt/rtcds/caltech/c1/scripts/SUS/F2Pcalc.py, I got new f2a filters.

  5. Overwrote f2a filters in C1:SUS-PRM_TO_COIL_(1-4)_1 FM1 with new ones, and turned  new f2a filters on.

Result:
  Below is the DC gain adjustment result from F2P_LOCKIN.py;

multiplier factors are :
UL = 1.141525
UR = 0.879997
LR = 1.117484
LL = 0.860995
Set C1:SUS-PRM_ULCOIL_GAIN to 1.04990177238
Set C1:SUS-PRM_URCOIL_GAIN to -0.983396190716
Set C1:SUS-PRM_LRCOIL_GAIN to 0.954304254663
Set C1:SUS-PRM_LLCOIL_GAIN to -0.971356852259


  So, UR/LL coil gains somehow got ~10 % larger than other two since last coil balancing.

  Measured coupling coefficients from F2P_LOCKIN.py were

- measured coupling coefficients are :
P2P(POS=>PIT) = 0.014993
P2Y(POS=>YAW) = 0.001363


  New f2a filters are plotted below. They look fairly different compared with previous ones.
PRM_f2a.png


 

We need better F2P_LOCKIN.py:
  Some one should make F2P_LOCKIN.py better. The main problem is the sudden gain change when starting diagonalization at low frequency. It sometimes trips off the watchdog.

Some elogs related:
  Kiwamu made f2a filters in Sep 2011: elog #5417
  Koji adjusting DC gains in Jan 2013: elog #7969

  8094   Sat Feb 16 18:32:01 2013 yutaSummaryRF Systemphase tracker: OLTF

I measured openloop transfer function of the phase tracking loop for the first characterization of phase tracker.

What is phase tracker:

  See elog #6832.
  For ALS, we use delay-line frequency discriminator, but it has trade-off between sensitivity and linear range. We solved this trade-off by tacking the phase of I/Q signals.
  Figure below is the current diagram of the frequency discriminator using phase tracker.
phasetracker.png

OLTF of phase tracking loop:
  Below. UGF at 1.2 kHz, phase margin 63 deg for both BEATX and BEATY. Phase delay can be clearly explained by 61 usec delay. This delay is 1 step in 16 KHz system.
  Note that UGF depends on the amplitude of the RF input. I think this should be fixed by calculating the amplitude from I/Q signals.
  BEAT(X|Y)_PHASE_GAIN were set to 300, and I put -3dBm 100 MHz RF signal to the beatbox during the measurement.
BEATX:BEATXFINEPHASE_OLTF.png BEATY:BEATYFINEPHASE_OLTF.png

Other measurements needed:

 - Linear range: By sweeping the RF input frequency and see sensitivity dependence.
 - Bandwidth: By measuring transfer function from the modulation frequency of the RF input to phase tracker output.
 - Maximum sensitivity: Sensitivity dependence on delay-line length (see PSL_Lab #825).
 - Noise: Lock oscillator frequency with phase tracker and measure out-of-loop frequency noise with phase tracker.
 - Sensitivity to amplitude fluctuation: Modulate RF input amplitude and measure the sensitivity.

  8095   Sat Feb 16 19:23:17 2013 yutaUpdateLSCPR2 flipped PRMI locked

It is my pleasure to announce that the first lock of PR2 flipped PRMI was succeeded.



POP looks very nice. TEM00 and not wobbling.
We need more I/Q phase and gain/filter adjustment and characterization soon.

Some more details:
  MICH error signal: AS55_Q_ERR (using POP55 PD; phase rotation angle 70 deg)
  PRCL error signal: REFL11_I_ERR (phase rotation angle 80 deg)
  MICH feedback: BS (MICH_GAIN = -60)
  PRCL feedback: PRM (PRCL_GAIN = -0.5)

  8099   Mon Feb 18 18:28:01 2013 yutaBureaucracyAlignmentwe are going to pump down

We will start preparing for pumping down. Main goal for this is to demonstrate PRFPMI using ALS.
Here are to-dos before we pump down.

Feb 18 eveing
- check input beam and Y arm alignment again
- IPPOS/IPANG alignment
- check all oplevs

Feb 19 morning
- open ETMX chamber heavy door
- align BS to X end
- adjust OSEM values (added by YM)
- center beam on all AS optics
- make sure AS/REFL is clear
- take picture of flipped PR2 (added by YM)
- make sure green is not clipped by new PRM oplev mirrors  (added by YM)
- center all oplevs

Feb 19 afternoon - Feb 20 morning
- close PSL shutter
- close all heavy doors and put the access connector back
- start pumping down

Feb 20 evening
- start aligning IFO

  8102   Tue Feb 19 00:21:09 2013 yutaUpdateElectronicsPOP path set up but AS55 is broken

Hmm......
I thought AS55 is broken because it was not responding to the AS beam nor flashlight in DC. What's the DC gain difference between AS55 and POP55 (or REFL55)?

Quote:

I undertook the investigation of the AS55 PD. I found the PD is not broken.

  8103   Tue Feb 19 02:23:40 2013 yutaBureaucracyGeneralaction items for PRFPMI

These are things need to be done for demonstrating PRFPMI using ALS.
All of these should be done before March 8!

CDS:
    - Fix c1iscex -JAMIE (done Feb 19: elog #8109)
    - Is ASS and A2L working? -JENNE
    - Are all whitening filters for PDs toggling correctly? -JENNE, JAMIE

PRMI locking:
    - Adjust I/Q rotation angles for error signals -JENNE, YUTA
    - Adjust filters -JENNE, YUTA
    - Coil balancing for BS (and ITMs/ETMs) -YUTA

PRC characterization in PRMI:

    - Measure PR2 loss from flipping -MANASA
    - Measure mode matching ratio -JENNE, YUTA
    - Measure finesse, PR gain -JENNE, YUTA
    - Calibrate PRM and/or ITM oplevs -MANASA, YUTA
    - Measure g-factor by tilting PRM or ITMs -JAMIE, YUTA
    - Calculate expected mode matching ratio and g-factor -JAMIE
    - Calculate expected finesse, PR gain -JENNE
    - Align aux laser into AS port? -ANNALISA?

ALS:
    - What's the end green situation? Optical layout changed? Laser temperature in CDS? -MANASA
    - What's the PSL green situation? Green trans cameras/PD? -JENNE, MANASA
    - Make ALS handing off to DARM/CARM LSC script -JENNE, YUTA
    - Demonstrate FPMI using ALS -JENNE, YUTA
    - Phase tracker characterization -YUTA, KOJI

PRFPMI:
    - Measure mode matching between PRC and arms -JENNE, YUTA
    - Measure PR gain -JENNE, YUTA
    - Calculate expected finesse, PR gain -JENNE

Others:
    - Update optical layout CAD after PR2 flipping -JAMIE, MANASA
    - AS55 situation? -YUTA
    - Look into PMC drift -JENNE, MANASA
    - Measure RFAM contribution to error signals -YUTA

 


Please fix, add or update if you notice anything.

  8105   Tue Feb 19 08:06:02 2013 yutaUpdateElectronicsPOP path set up but AS55 is broken

I didn't use LED flash light. We learned from the past (elog #7355). I checked that POP55 and REFL55/165/33/11 are clearly responding to flash flight, but I didn't expect that much difference in DC gain.
I wonder why we could align AS beam to AS55 in Feb 8 (elog #8030), but not in Feb 15 (elog #8091). I will check during the pump down.

Quote:

10010 Ohm for POP55 vs 50 Ohm for AS55 (cf. http://nodus.ligo.caltech.edu:8080/40m/4763)

I wonder if you used an LED flash light, which emits no IR.

  8112   Tue Feb 19 19:55:52 2013 yutaUpdateIOOMC yaw input tuned

[Jenne, Manasa, Yuta]

Since we levelled IMC stack, we had to center beam spots on MC mirrors again.
We did this by steering PSL mirror in yaw (about same amount but opposite direction to what we did in elog #8077)
Residual beam tilt compared with a line through MC1 and 3 actuator nodes is ~ 15 mrad, mainly in yaw.
MCdecenter_19Feb2013.png

  8114   Wed Feb 20 03:13:10 2013 yutaUpdateAlignmentclipping centering checklist

I attached clipping/centering checklist for the alignment.
Blue ones are the ones we checked today. Red ones should be checked tomorrow. Circles indicate centering on the optics, rectangles indicate clipping check, and arrows indicate retro-reflecting or bounces.
We found mis-centering on MMT1, PR2 and SR3 tonight (by ~0.5 beam diameter). They are also indicated.

I think we don't want to touch MMT1 and PR2 anymore, because they change input beam pointing.
I'm a little bit concerned about high beam on SR3, because we had PRC flashing in vertical higher order modes. We also see ETMX slider values high in pitch (~ 5.4).
Also, the diameter of ETMX reflected beam on ITMX looked larger and dimmer than ITMX transmitted beam, which doesn't seem reasonable.


Wednesday, Feb 20:
 - tweak TT1/TT2 and PRM so PRC flashes
 - re-check Yarm/Xarm bounces
 - center beam on all AS optics, starting from SR2
 - make sure REFL and AS is clear
 - check if TRY/TRX are coming out from the ends
 - check beam centering on mirrors in IMC/OMC chamber as far as you can reach
 - inject green from both ends
 - make sure green beams are not clipped by mirrors on BS chamber, IMC/OMC chamber
 - re-center all oplevs, with no clipping
 - check all OSEM values
 - take pictures of flipped PR2 and input TTs (and everything)
 - close all heavy doors and put the access connector back

Thursday, Feb 21:
 - make sure we can lock PRMI
 - start pumping down when Steve arrives

Attachment 1: ClippingCenteringChecklist.pdf
ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf
  8115   Wed Feb 20 10:13:41 2013 yutaUpdateAlignmentPRC flashing brighter than last week

After in-vac alignment work last night, PRC is flashing brighter than PRMI alignment last week.
My hypothesis is that "we aligned PRM to junk MI fringe last week". Possibly, we used MI fringe caused by AR reflection of ITMs, or MI fringe reflected from SRM.

Videos:
  PRC flashing last week (youtube, elog #8085, elog #8091)

  PRC flashing this time (Lens in-front of AS camera was taken out)



My hypothesis can explain:
 - why we had dimmer POP last week (flash in half-PRC was way brighter even when we had more attenuators (youtube))
 - why I thought AS55 is broken (AS was too dim)

Conclusion:
  Be careful of junk beams.

  8119   Wed Feb 20 19:48:16 2013 yutaUpdateAlignmentBS table oplev re-arranged

[Sendhil, Yuta]

After aligning IFO and putting the access connector on, we also centered IPANG/IPPOS and all oplevs (except SRM).
To avoid clipping of PRM/BS oplevs, we re-arranged oplev steering mirrors on BS table.

What we did:
  1. Checked IPANG comes out unclipped after putting on the access connector.
  2. Centered IPANG on its QPD.
  3. Checked oplevs beams for ITMX/ITMY centered on in-vac mirrors, and centered them on their QPDs.
  4. Checked IPPOS beam is centered on the mirrors inside BS chamber, and centered IPPOS on its QPD.
  5. Tweaked oplev mirrors on BS chamber to make PRM/BS oplev beam unclipped and centered on mirrors, and centered them on their QPDs. To avoid clipping of oplev beams in BS table, we re-arranged oplev steering mirrors on BS table (outside the vaccum).


Current status:
  QPD values, IFO_ALIGN/MC_ALIGN screens, OSEM values attached.

  - IR incident beam and IFO aligned
  - X/Y end green coming out to PSL table (in higher order modes)
  - IPANG/IPPOS available
  - All oplevs available
  - AS/REFL/POP cameras ready
  - access connector, ETMX/ETMY heavy doors on
  - ITMX/ITMX/BS heavy doors are not on
  - AS/REFL/POP PDs not centered
  - POX/POY/TRX/TRY not aligned
  - AS beam coming out of the OMC chamber low by ~ 1 beam diameter (my bad)


Tomorrow:
  - Align AS/REFL/POP PD and lock PRMI
  - Take pictures of ITMX/ITMY/BS stacks
  - Put heavy doors on ITMX/ITMY/BS chambers
  - Start pumping down

Attachment 1: IFOALIGN_QPDs_OSEMs.png
IFOALIGN_QPDs_OSEMs.png
  8121   Wed Feb 20 20:15:29 2013 yutaUpdateAlignmentSRM oplev status

Currently, SRM is misaligned in pitch so that SRM reflected beam hits on the top edge of SR3 (not on the mirror, but on the cage holding the mirror).
We also confirmed that SRM oplev beam is coming out from the chamber unclipped, and centered on QPD when SRM is "aligned".

  8122   Wed Feb 20 20:58:37 2013 yutaUpdateAlignmentclipping centering checklist

Blue ones are the ones we checked yesterday.
Green ones are the ones we checked today.
Red ones are the ones we couldn't check.

We noticed mis-centering on green optics and partial clipping of higher order modes, but we did not touch any green optics in-vac. This is because green beam from Y end and X end has different spot positions on the green optics after periscopes. We confirmed that direct green beam from ends are not clipped.

I believe we have checked everything important. Any other concerns?

Attachment 1: ClippingCenteringChecklist.pdf
ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf ClippingCenteringChecklist.pdf
  8124   Wed Feb 20 21:56:08 2013 yutaUpdateAlignmentclipping centering checklist

I'm not sure about the OMC situation at 40m. I think there are no direct beam reflected back into IFO from OMC path. There must be some backscatter, but we have to open OMC chamber again to put a beam dump.
I don't think we want to put one in OMC path for this pump-down, but we can put a beam dump to dump reflected beam from mis-aligned SRM tomorrow, if available.

  8129   Thu Feb 21 15:21:07 2013 yutaUpdateVACall heavy doors on, started pumping down annulus

[Steve, Manasa, Jenne, Sendhil, Evan, Yuta]

We put heavy doors on ITMX/ITMY/BS chamber and started pumping down from annulus.

What we did:
  1. Replaced POP55 with AS55 back, because it was not broken.
  2. Centered on AS55, REFL55, REFL11, POPDC PD.
  3. Tried to lock PRMI, but I couldn't lock even MI stably for more than 1 min. I believe this is because it was noisy this morning. But I checked again that REFL/POP/AS beams are coming out without clipping and we have some error signals.
  4. Noticed AS beam has less range in left (on AS camera), so we tweaked OM4 a little to make more room.
  6. Took pictures inside ITMX and BS chambers
  7. Put heavy doors on ITMX/ITMY/BS chambers.
  8. Started pumping down annulus.
  9. Recentered IPANG/IPPOS and oplevs on their QPDs.

POP, REFL, AS:

  8141   Sat Feb 23 00:34:28 2013 yutaUpdateComputerscrontab in op340m deleted and restored (maybe)

I accidentally overwrote crontab in op340m with an empty file.
By checking /var/cron in op340m, I think I restored it.

But somehow, autolockMCmain40m does not work in cron job, so it is currently running by nohup.

What I did:
  1. I ssh-ed op340m to edit crontab to change MC autolocker to usual power mode. I used "crontab -e", but it did not show anything. I exited emacs and op340m.
  2. Rana found that the file size of crontab went 0 when I did "crontab -e".
  3. I found my elog #6899 and added one line to crontab

55 * * * *  /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m >/cvs/cds/caltech/logs/scripts/mclock.cronlog 2>&1

  4. It didn't run correctly, so Rana used his hidden power "nohup" to run autolockMCmain40m in background.
  5. Koji's hidden magic "/var/cron/log" gave me inspiration about what was in crontab. So, I made a new crontab in op340m like this;

34 * * * *  /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m >/cvs/cds/caltech/logs/scripts/mclock.cronlog 2>&1
55 * * * * /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/PSL/FSS/RCthermalPID.pl >/cvs/cds/caltech/logs/scripts/RCthermalPID.cronlog 2>&1
07 * * * * /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/PSL/FSS/FSSSlowServo >/cvs/cds/caltech/logs/scripts/FSSslow.cronlog 2>&1
00 * * * * /opt/rtcds/caltech/c1/burt/autoburt/burt.cron >> /opt/rtcds/caltech/c1/burt/burtcron.log
13 * * * * /cvs/cds/caltech/conlog/bin/check_conlogger_and_restart_if_dead
14,44 * * * * /opt/rtcds/caltech/c1/scripts/SUS/rampdown.pl > /dev/null 2>&1


  6. It looks like some of them started running, but I haven't checked if they are working or not. We need to look into them.

Moral of the story:
  crontab needs backup.

  8143   Sat Feb 23 07:14:58 2013 yutaUpdateLSCcan't lock Y arm

I tried to align and lock Y arm for the first time after pumping.
But I couldn't lock Y arm for more than ~1 sec. Why?


What I did:
  1. Centered IPANG/IPPOS using input TT1/TT2.

  2. Restored ITMY/ETMY slider values when it was aligned before pumping. I saw tiny flashes in TRY PD at this point.

  3. Replaced Ygreen REFL camera with ETMYT camera to see transmitted beam mode.

  4. Used TT1/TT2 and ITMY/ETMY to get ~ 0.4 peak in normalized TRY PD output (C1:LSC_TRY_OUT).

  5. Centered POY beam on POY11 PD.

  6. Changed I/Q mixing angle (C1:LSC-POY11_PHASE_R) from -61 deg to -16 deg to get good PDH signal in I_ERR (attached).

  7. Ran LSCoffsets script (now on LSC_OVERVIEW screen) to adjust PD offsets.

  8. Tried to lock Yarm with different gains, but failed. When lock is acquired, TRY fluctuates ~50 % and unlocks suddenly.


What I found:
  1. There was some OFFSETs left turned on in suspension screens. Don't leave them on!! They change alignment of the optics. I will leave it on until we complete Yarm alignment.

  2. C1:SUS-(ITMY|ETMY)_ASC(PIT|YAW) was kept oscillating the optic since Dec 17, 2013. I think this is from interrupted ASS script. Your script should restore everything when interrupted!


Next:
  - Beamspot on ITMY looks off-centered. Maybe A2L is causing unstable lock?
  - Maybe F2A is causing unstable lock?
  - More alignment?
  - FSS related? crontab related?

Attachment 1: TRYPOY.png
TRYPOY.png
  8146   Sat Feb 23 15:26:26 2013 yutaUpdateComputerscrontab in op340m updated

I found some daily cron jobs for op340m I missed last night. Also, I edited timings of hourly jobs to maintain consistency with the past. Some of them looks old, but I will leave as it is for now.
At least, burt, FSSSlowServo and autolockMCmain40m seems like they are working now.
If you notice something is missing, please add it to crontab.

07 * * * * /opt/rtcds/caltech/c1/burt/autoburt/burt.cron >> /opt/rtcds/caltech/c1/burt/burtcron.log
13 * * * * /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/PSL/FSS/FSSSlowServo >/cvs/cds/caltech/logs/scripts/FSSslow.cronlog 2>&1
14,44 * * * * /cvs/cds/caltech/conlog/bin/check_conlogger_and_restart_if_dead
15,45 * * * * /opt/rtcds/caltech/c1/scripts/SUS/rampdown.pl > /dev/null 2>&1
55 * * * *  /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m >/cvs/cds/caltech/logs/scripts/mclock.cronlog 2>&1
59 * * * * /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/PSL/FSS/RCthermalPID.pl >/cvs/cds/caltech/logs/scripts/RCthermalPID.cronlog 2>&1

00 0 * * * /var/scripts/ntp.sh > /dev/null 2>&1
00 4 * * * /opt/rtcds/caltech/c1/scripts/RGA/RGAlogger.cron >> /cvs/cds/caltech/users/rward/RGA/RGAcron.out 2>&1
00 6 * * * /cvs/cds/scripts/backupScripts.pl
00 7 * * * /opt/rtcds/caltech/c1/scripts/AutoUpdate/update_conlog.cron

  8150   Sat Feb 23 17:14:59 2013 yutaUpdateLSCcan't lock Y arm

Jenne found that;
  0. If all mirrors are "aligned," Yarm flashes.
  1. If SRM is misaligned, Yarm doesn't flash.
  2. If BS is misaligned, Yarm doesn't flash.
  3. If ITMX is misaligned, Yarm still flashes.

So, my hypothesis from this is that I was playing with " TT1 -> TT2 -> ITMY -> BS -> SRM -> BS -> Yarm "  configuration last night.
This hypothesis can explain;
  1. Why I could not get TRY peak more than 0.5 (additional BS reflection makes incident power to Yarm less).
  2. Why I had to change POY11 I/Q mixing angle by ~ 45 deg (because EOM to Yarm length changed).
  3. Why I couldn't lock Yarm stably (additional reflection by BS and SRM made too much beam jitter?).

We are now trying to get "real" Yarm flash.

  8157   Mon Feb 25 15:30:29 2013 yutaUpdateAlignmentY arm locked, both colors

[Koji, Yuta]

We aligned Y arm to Y green and tweaked TT1/TT2 to get IR locked in Y arm.

Alignment procedure:
  1. Align ETMY/ITMY to maximize TEM00 green transmission to PSL table. We reached ~240 uW.

  2. Aligned PRM and TT2 so that PRM reflected beam go through FI and get ITMY-PRM cavity flashing. This is to coarsely align input pointing to Y arm. After this alignment, we got tiny Y arm flash. Input pointing to IPANG QPD was lost.

  3. Aligned TT1/TT2 to maximize TRY in TEM00. We reached ~0.92.

Failed procedure:

  I was struggling with finding Y arm flash. I was using IPPOS/IPANG as input pointing reference, and slider values (C1:SUS-(ITMY|ETMY)_(PIT|YAW)_COMM) or OSEM values (C1:SUS-(ITMY|ETMY)_SUS(PIT|YAW)_IN1) before pumping for Y arm alignment reference. But it was a lot more easier if Y arm is aligned to green and having Yarm cavity axis assured.

Next:
  - X arm flash in IR
  - Steer X end green
  - If X arm or AS looks bad, adjust IR input pointing and Y arm alignment. We have to steer Y end green afterwards.

  8162   Mon Feb 25 21:25:14 2013 yutaUpdateAlignmentboth arms locked in IR

[Jenne, Evan, Yuta]

After Y alignment, X arm is aligned to IR and we got both arms locked in IR.
There's some dift (input pointing?) and this made aligning both arms tough. I will elog about it later.
Attached is ETMYF. ETMXF, ITMYF, ITMXF when both arms are locked by IR.

Alignment Procedure:
  1. Algined BS/ITMX to get MI fringe in AS. We got X arm flashing at this point.
  2. Use BS/ITMX/ETMX to get TRX maximized, without losing good MI fringe in AS. We reached 0.75.
  3. There was clipping of TRX beam at Xend optics. Since whole IFO alignment is started from Y green, this clipping is because of poor Y green pointing. But we needed clear TRX for aligning Xarm, so we re-arranged Xend TRX path to avoid clipping.

X arm issues:
  - Beam motion at TRX is larger than TRY. Turning off clean table air didn't help. Maybe we need BS oplev on or ETMX coil gain balancing.
  - X green scatters into TRX PD and ETMXT camera. Fix them.

Attachment 1: QUAD1_1045890588.png
QUAD1_1045890588.png
  8164   Mon Feb 25 22:42:32 2013 yutaSummaryAlignmentcurrent IFO situation

[Jenne,Yuta]

Both arms are aligned starting from Y green.
We have all beams unclipped except for IPANG. I think we should ignore IPANG and go on to PRMI locking and FPMI locking using ALS.
IPANG/IPPOS and oplev steering mirrors are kept un-touched after pumping until now.

Current alignment situation:
 - Yarm aligned to green (Y green transmission ~240 uW)
 - TT1/TT2 aligned to Yarm (TRY ~0.86)
 - BS and Xarm alined to each other (TRX ~ with MI fringe in AS)
 - X green is not aligned yet
 - PRMI aligned

Current output beam situation:
 IPPOS - Coming out clear but off in yaw. Not on QPD.
 IPANG - Coming out but too high in pitch and clipped half of the beam. Not on QPD.
 TRY   - On PD/camera.
 POY   - On PD.
 TRX   - On PD/camera.
 POX   - On PD.
 REFL  - Coming out clear, on camera (centered without touching steering mirrors).
 AS    - Coming out clear, on camera (centered without touching steering mirrors).
 POP   - Coming out clear, on camera (upper left on camera).


Oplev values:

Optic    Pre-pump(pit/yaw)    PRFPMI aligned(pit/yaw)
ITMX    -0.26 /  0.60         0.25 /  0.95
ITMY    -0.12 /  0.08         0.50 /  0.39
ETMX    -0.03 / -0.02        -0.47 /  0.19
ETMY     0.37 / -0.62        -0.08 /  0.80
BS      -0.01 / -0.18        -1    /  1 (almost off)
PRM     -0.34 /  0.03        -1    /  1 (almost off)


 All values +/- ~0.01. So, oplevs are not useful for alignment reference.

OSEM values:
Optic    Pre-pump(pit/yaw)    PRFPMI aligned(pit/yaw)
ITMX    -1660 / -1680        -1650 / -1680
ITMY    -1110 /   490        -1070 /   440
ETMX     -330 / -5380         -380 / -5420
ETMY    -1890 /   490        -1850 /   430
BS        370 /   840          360 /   800
PRM      -220 /  -110         -310 /  -110


  All values +/- ~10.
  We checked that if there's ~1200 difference, we still see flash in Watec TR camera. So, OSEM values are quite good reference for optic alignment.

IPANG drift:
  On Saturday, when Rana, Manasa, and I are trying to get Y arm flash, we noticed IPANG was drifting quite a lot in pitch. No calibration is done yet, but it went off the IPANG QPD within ~1 hour (attached).
  When I was aligning Yarm and Xarm at the same time, TRY drifted within ~1 hour. I had to tweak TT1/TT2 mainly in yaw to keep TRY. I also had to keep Yarm alignment to Y green. I'm not sure what is drifting so much. Suspects are TT2, PR2/PR3, Y arm and Y green.

  I made a simple script(/opt/rtcds/caltech/c1/scripts/Alignment/ipkeeper) for keeping input pointing by centering the beam on IPPOS/IPANG using TT1/TT2. I used this for keeping input pointing while scanning Y arm alignment to search for Y arm flash this weekend (/opt/rtcds/caltech/c1/scripts/Alignment/scanArmAlignment.py). But now we have clipped IPANG.


So, what's useful for alignment after pumping?:

  Optic alignment can be close by restoring OSEM values. For input pointing, IPPOS/IPANG are not so useful. Centering the beam on REFL/AS (POP) camera is a good start. But green works better.

Attachment 1: IPANGdrift.png
IPANGdrift.png
  8177   Wed Feb 27 01:09:53 2013 yutaUpdateLockingPRMI sideband/carrier locked

[Jenne,Yuta]

We succeeded in locking PRMI in sideband and carrier.
Measured power recycling gain was ~60 power recycling gain was 4 (edited by YM on Feb 27; see elog #6947), but we have many things we cannot explain.

Snapshots:
  Here you are, Jamie.

PRMI sideband locked
POP_1045983973.bmp REFL_1045983963.bmp AS_1045983954.bmp


PRMI carrier locked
POP_1045986718.bmp REFL_1045986730.bmp AS_1045986710.bmp

  I centered POP camera and put attenuator to take these snapshots.

  Compare with previous ones.

Aug 17, 2012 elog #7213
Jun 28, 2012 elog #6886
Mar 15, 2012 elog #6421


Locking details:
 == MI only ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg, MICH_GAIN = -7, feedback to BS

 == PRMI sideband ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = 24.5 deg,  MICH_GAIN = -0.05 (acquisition) -> -5 (UGF ~100 Hz), feedback to BS
  PRCL: REFL33_I_ERR, REFL33_PHASE_R = -22.65 deg, PRCL_GAIN = 4 (UGF ~120 Hz), feedback to PRM

 == PRMI carrier ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = 24.5 deg,  MICH_GAIN = -0.08 (couldn't measure UGF), feedback to BS
  PRCL: REFL33_I_ERR, REFL33_PHASE_R = -22.65 deg, PRCL_GAIN = -0.3 (couldn't measure UGF), feedback to PRM


Power recycling gain:
  POPDC was 32 when PRM is misaligned, 25 when PRMI sideband locked, ~2000 when PRMI carrier locked.
  This means, power recycling gain is ~60 power recycling gain is ~4 (=POPlocked/POPmis*T_PRM=2000/30*0.06). Expected power recycling gain for PRMI is ~45, when there's no loss (see elog #6947).

  I reduced POPDC PD gain so that it doesn't saturate.


Issues:
  - We optimized AS55_PHASE_R to -12 deg by looking at MI signal. But somehow, -12 deg didn't work for PRMI.
  - Somehow, REFL11_I didn't work to lock PRCL.
  - REFL11_Q didn't work to lock MI. SNR not enough?
  - We saw POPDC flashing up to ~15000. What is this?
  - Carrier lock was not stable, we couldn't hold for more than ~30 sec. It looks like PRM moves too much when PRMI is locked.
  - Input pointing is drifting a lot in pitch. I had to re-align TT2/TT1 to the arms every ~1 hour to get good MI alignment. When I tweak TT2/TT1, both TRY and TRX gets better. I think this shows that input pointing is drifting, not the arms.


Next:
 - redo PRM/BS coil balancing
 - optimize REFL33 rotation phase
 - stabilize carrier lock somehow
 - measure PRC g-factor

  8181   Wed Feb 27 11:22:54 2013 yutaUpdateComputersbackup crontab

I made a simple script to backup crontab (/opt/rtcds/caltech/c1/scripts/crontab/backupCrontab).

#!/bin/bash

crontab -l > /opt/rtcds/caltech/c1/scripts/crontab/crontab_$(hostname).$(date '+%Y%m%d%H%M%S')


I put this script into op340m crontab.

00 8 * * * /opt/rtcds/caltech/c1/scripts/crontab/backupCrontab

It took me 30 minutes to write and check this one line script. I hate shell scripts.

  8182   Wed Feb 27 11:59:43 2013 yutaUpdateSUSPRM/BS coil re-balanced

I re-adjusted coil gains and f2a filters for PRM and BS.
I'm not sure what happened to PRM since I balanced on Feb 16(elog #8093).
Let's see if it helps PRMI locking or not.


========== PRM ==========

- Original DC coil gains

C1:SUS-PRM_ULCOIL_GAIN 1.049901772380000e+00
C1:SUS-PRM_URCOIL_GAIN -9.833961907160000e-01
C1:SUS-PRM_LRCOIL_GAIN 9.543042546630000e-01
C1:SUS-PRM_LLCOIL_GAIN -9.713568522590000e-01

- New DC coil gains


multiplier factors are :
UL = 0.928167
UR = 1.061448
LR = 0.941659
LL = 1.068726
Set C1:SUS-PRM_ULCOIL_GAIN to 0.974482231437
Set C1:SUS-PRM_URCOIL_GAIN to -1.04382410014
Set C1:SUS-PRM_LRCOIL_GAIN to 0.898628670041
Set C1:SUS-PRM_LLCOIL_GAIN to -1.03811466772

- New f2p filters

- measured coupling coefficients are :
P2P(POS=>PIT) = 0.023968
P2Y(POS=>YAW) = 0.007075

PRM_f2a20130227.png



========== BS ==========

- Original DC coil gains

C1:SUS-BS_ULCOIL_GAIN 1.037692431800000e+00
C1:SUS-BS_URCOIL_GAIN -1.016268296990000e+00
C1:SUS-BS_LRCOIL_GAIN 9.660800075010000e-01
C1:SUS-BS_LLCOIL_GAIN -9.791833500410000e-01

- New DC coil gains


multiplier factors are :
UL = 1.017855
UR = 1.023207
LR = 0.956184
LL = 1.002755
Set C1:SUS-BS_ULCOIL_GAIN to 1.0562177496
Set C1:SUS-BS_URCOIL_GAIN to -1.03985422464
Set C1:SUS-BS_LRCOIL_GAIN to 0.923750146975
Set C1:SUS-BS_LLCOIL_GAIN to -0.981880297098

- New f2p filters

- measured coupling coefficients are :
P2P(POS=>PIT) = 0.038251
P2Y(POS=>YAW) = -0.014677

BS_f2a20130227.png

  8196   Thu Feb 28 02:43:49 2013 yutaUpdateLSCsome qualitative evidence of PRMI sideband lock

[Manasa, Yuta]

Since we have setup POP22 PD now(elog #8192), we could confirm that sideband power builds up when PRMI is sideband locked.

Plot:
  Here's some plot of PRC intra-cavity powers and MICH,PRCL error signals. As you can see from POP22, we locked at the peak of 11MHz sideband. There was oscillation at ~500 Hz, but we couldn't optimize the gain yet.
PRMIsideband.png


Movie:
  Here's 30 sec movie of AS, POP, REFL when acquiring (and losing) PRMI sideband lock. It was pretty hard to take a movie because it locks pretty seldom (~1 lock / 10 min).



Locking details:
  For MICH lock, we used ITMs instead of BS for reducing coupling between PRCL.
  Also, AS55 phase rotation angle was coarsely optimized by minimizing MICH signal in I.
  For PRCL lock, we used REFL55_I_ERR instead of REFL33_I_ERR. It had better PDH signal and we coarsely optimized phase rotation angle by minimizing PRCL PDH signal in Q.

 == PRMI sideband ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -0.1, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = -15, feedback to PRM

  We set POP22_PHASE_R = -170 deg by minimizing Q.

Issues:
 - We tried to use REFL55_Q_ERR to lock MICH, but couldn't. It looks like REFL error signals are bad.
 - We tried to use POP22_I_ERR to trigger PRCL lock, but it didn't work.

  8197   Thu Feb 28 03:25:27 2013 yutaUpdateLSCPR gain ~ 25 from PRMI carrier lock

[Manasa, Yuta]

We locked PRMI in carrier. Measured power recycling gain was ~25.

Plot:

  Here's some plot of PRC intra-cavity powers and MICH,PRCL error signals. As you can see from POPDC, cavity buildup was about 400, which means power recycling gain was ~25. Power recyling gain is fluctuating up to ~45 during lock. We need some gain normalization or something.
PRMIcarrier.png


Movie:

  Here's 30 sec movie of AS, POP, REFL when acquiring PRMI carrier lock. Although there's oscillation when acquiring lock, beam spot motion is less and stable compared with the past(before flipping PR2).



Locking details:
 == PRMI carrier ==
  MICH: AS55_Q_ERR, AS55_PHASE_R = -12 deg,  MICH_GAIN = -0.1, feedback to ITMX(-1),ITMY(+1)
  PRCL: REFL55_I_ERR, REFL55_PHASE_R = 70 deg, PRCL_GAIN = 5, feedback to PRM


Next:
  - Better filters and gains for stable lock
  - Kakeru method to measure g-factor (see elog around #1434)
  - OSA to measure g-factor

  8199   Thu Feb 28 05:54:54 2013 yutaUpdateRF Systemphase tracker: calibration

I swept the frequency of RF input to the beatbox to calibrate and check linearity range of phase tracker.
Calibration factors are;
  C1:ALS-BEATX_FINE_PHASE_OUT    52.1643 +/- 0.0003 deg/MHz
  C1:ALS-BEATY_FINE_PHASE_OUT    51.4788 +/- 0.0003 deg/MHz


There was systematic error to the linearity check, but at least, calibration factor changes less than 50 % in the frequency range of 10 MHz to more than 500 MHz.


What I did:
  Used network analyzer(Aligent 4395A) to sweep the frequency RF input to the beatbox and getdata of phase tracker signal. I swept from 10 Hz to 500 MHz with 501 points in 50 sec. This sweep is slow enough considering we could lock the 40m arms (typical speed of a mirror is 1 um/s, so bandwidth of the phase tracker should be more than 1 um/sec / 40 m * 3e14 Hz = 75 MHz/s).
  RF amplitude was set to be -3 dBm and splitted into BEATX and BEATY.


Result:
  Plots for BEATX and BEATY are below;
ALS-BEATX_FINE_PHASE_OUT.pngALS-BEATY_FINE_PHASE_OUT.png


Discussion:
  - Considering delay line length is ~30m, expected calibration factor is;

    2*pi*l/v = 2*pi * 30 m / (2e8 m/s) = 0.94 rad/MHz = 54 deg/MHz

so, this calibration is reasonable.

  - Since frequency sweep of network analyzer is not continuous, phase tracker output is like steps with some ringdown. This makes some systematic error for checking linearity. I'm planning to do slower sweep or continuous sweep. Also, the phase tracker seems like he can exceed 500 MHz.

  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.

Result:
frequencynoise.png

Discussion:
  - 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).

Attachment 1: POX11_630Hz.png
POX11_630Hz.png
  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)
LSCMICHOLTF_PRMI.png    LSCPRCLOLTF_PRMI.png



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).


Youtube:





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.


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

Attachment 3: PRMtoAS55REFL55.png
PRMtoAS55REFL55.png
  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.
frequencynoisewhitening.png


Next:
  - 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.

Result:
  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.

Discussion:
  [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.

PRMIgfactorPlan.png

  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.


Scripts:
  /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

  etc...


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).


Next:
 - 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).

Method:
  Same as in elog #8221.

Result:
 
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.


Script:
  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).


Result:
  Below are the plots of fitted curves.

ITMY_YAW_20130305_DC.pngPRM_PIT_20130305a_DC.pngPRM_YAW_20130305b_DC.png


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).

Next:
  - 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.

PRMangularmotion.png

  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.
LSCMICHOLTF_MI.png

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


  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.

Result:
  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.
IPangulardrift.png

Discussion:
  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.

Note:
  - 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).


burtlookup.py
  in ./scripts/general/burtlookup.py

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


GRtoggler.py
  in ./scripts/ALS/GRtoggler.py

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


MCbeeper.py
  in ./scripts/MC/MCbeeper.py

  Beeps when MC is unlocked.


yutalib.py
  in ./scripts/pylibs/yutalib.py

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


pyezcalib.py
  in ./scripts/pylibs/pyezcalib.py

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


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


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


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


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


./scripts/SUS/ActuatorCalib
  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).
OLTF_PRCL.png


  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.

Result:
  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.
calibREFL55Q.png


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


Next:
  - 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.
LSCPRCLOLTF_PRITMY.png


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

  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.

Next:
  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).

CDS:

    - 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)

ALS:
    - 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

Others:
    - 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.

ELOG V3.1.3-