david.barker@LIGO.ORG - posted 08:23, Monday 01 September 2014 (13693)
CDS model and DAQ restart report, Saturday, Sunday 30th, 31st August 2014
no restarts reported
no restarts reported
Thursday, no restarts reported
model restarts logged for Fri 29/Aug/2014
2014_08_29 16:17 h1omc
2014_08_29 16:19 h1broadcast0
2014_08_29 16:19 h1dc0
2014_08_29 16:19 h1fw0
2014_08_29 16:19 h1fw1
2014_08_29 16:19 h1nds0
2014_08_29 16:19 h1nds1
2014_08_29 16:52 h1fw0
no unexpected restarts. OMC model change and associated DAQ restart.
Sadly, the RF phase in ASAIR_A_RF45 changed again (see the previous report).
This time, an optimum demodulation phase for the simple Michelson was found to be 30 deg in ASAIR_RF45 while it was 14 deg last night. If we blame today's table repositioning (see alog 13683) for this phase shift, the ASAIR path would have shifted by (3 x 108 m/s) / (45 MHz) x (16 deg) / (360 deg) = 30 cm. This seemed too big as we did not so much modify the setup. Also, I quickly checked the REFL_A_RF45 by locking PRX on the carrier. The optimum demodulation phase was 6.9 deg and this is slightly off from the last night which was 4.6 deg. No idea what is going on.
Nic, Kiwamu
We made a brief measurement for the ITMX spot position to study the alignment situation.
According to the result, the beam is off from the center roughly by 2.3 cm in yaw toward the Y arm. But, we are not confident with this number as we had some concerns in this measurement. We did not measure the off-centering in pitch yet.
(Method)
We shook the ITMX L2 stage at 2 Hz and monitored the oplev output and ASAIR_A_RF45_Q signal with the Michelson locked on a dark fringe. This is a type of the standard angle-to-length coupling measurement. By taking a transfer function at this excitation frequency from the oplev output to the length signal, we estimated the amout of the off-centering.
(Results)
According to the measurement, the angle motion in yaw was about 0.17 urad at the bottom stage and length coupling was about 0.21 nm both in rms. I used the MICH optical gain calibration that was obtained yesterday (see alog 13664), 5.8 x 109 counts / meters. Also, at 2 Hz, the MICH open loop has a gain of about 20, so the actual longitudinal motion would be 4.14 nm in rms. Dividing the two numbers, we obtained a off-centering of 2.4 cm. The orientation of the off-centering was then indendently checked by introducing some inbalance in the yaw actuation just like the usual spot position measurement (for example, see LLO alog 5010). Note that we assumed that the bottom stage moves at 180 deg off-phase compared with that of the exciation at the L2 stage.
(Some caveat and concerns)
Nic, Kiwamu 
(Variable finesse technique turned out to be good to start)
Since I have been unsuccessful in locking the PRMI in the past two or three days, I wanted to try some other locking technique. We tried LLO's variable finesse technique (see LLO alog 11340) which seemed more reliable than randomly adjusting the gains and triggers. It turned out that it almost repeatably locks the initial low finesse PRMI. Very nice. We then fiddled with the MICH gain which needed some gain correction as we got rid of the offset in the MICH locking point.
POPAIR_B_LF fluctuated a lot presumably due to some misalignment in some optics. POPAIR_B_LF was about 20000 counts in average and ASAIR_B_LF stayed approximately 3000 counts in average. After 15 minutes or so, we lost the lock for some reason, we did not have a close look.
The attached is a video of ASAIR when the PRMI was in lock.
The final configuration (i.e. the MICH locked on a zero-offset point) is shown in the attached screenshot.
Also, we newly installed a 100 Hz low pass filter in POPAIR_B_LF because high frequency noise in POPAIR_B_LF saturated the BS actuator through the normalization.
When the simple Michelson is locked on a dark fringe, POPAIR_B_LF is typically 120 counts. So the recycling gain is (20000 counts) x (Tp 3%) / (120 counts) = 5 which seems too small. Clipping loss somewhere ?
For the records, with 60W in the L1 recycling cavity, without the BS baffles the BS drift in PRMI carrier lock was about 5 urad (see LLO entry 9920). This is the only H1 PRMI carrier lock collected so far, but the only drifts we see are ~0.5urad.
Keita Kiwamu Nic
Also, with this table repositioning, we became able to monitor the OMC transmission through the GigE digital camera.
To get the OMC trans, we newly installed two 2" mirrors on the rightmost periscope and steered the beam onto the camera. Since the beam was relatively too big for the camera, we then installed a PLCX-50.8 to let the beam converge. The lens stands between the bottom periscope mirror and the camera. However, currently, the camera is not exactly at the focal point as there was a mode-master setup which prevented us from backing the camera further to the focal point.
Feel free to move (or remove) the ModeMaster setup -- this will need to be rearranged in any event, no need to keep it in place if it's a problem.
Nicolas, Keita, Dave
The h1omc model was modied. In the ASC block, 8 filtermodules were removed and 4 were added downstream. In the DAQ list, 8 OUT channels were removed and 4 OUT were added (all at 2048Hz). Four CLOCK channels were connected to the CLK outputs of the oscillators (previously they were tee'ed to the SIN outputs).
After the model was restarted, we restarted the DAQ to sync with the new INI file. The safe.snap restore was not good, so I manually burt restored to 16:10 (h1omc safe.snap needs updating).
Attached is an illustrated summary of the filter bank changes.
08:30 Peter- to H2 enclosure
09:01 Jason- to LVEA to have a look at the BSC2 Oplev LASER
09:10 Hugh- to End-X to change Parker valve
09:12 Richard- to HAM6 to check out installation
09:30 HEPI pump shutdown for valve replacement
09:40 Rich Mc- out of LVEA
10:15 End-X HEPI pup back up and runnin after Parker valve change-out
10:20 Dave- started cold cathode on HAM6
10:25 Travis- out to W Bay to work on Quad 3 IFO
10:53 Rich- out to HAM6 to have a look at Cold Cathode b. Not reading back
11:08 Rich- out of LVEA. Cold cathode reading good ~6.5e-06
11:15 Hugh- back from End-X
11:25 Cris- to End-X. not in VEA
11:35 Jason- out of Lvea. replaced BSC2 oplev laser
11:40 Nick- will be working on OMC. Will need to misalign ITMX
13:12 Nick- LVEA to ISCT6
13:30 reset SUS ETMX and TMSX Watchdogs
13:42 Nick out of LVEA
14:06 List of currently tripped WDs: HEPI HAM1, HAM6, IOPSEIH16; IOPSEIEY,SIETMY; IOPPEMMX; IOPSEIEX, SIETMX
14:20 Aaron - terminating 12V cables in Bier Garden
14:46 Hugh- introduced me to the new HEPI addition to the ALH
15:46 signed two work permits: #4821 & #4822
(2) weeks until next need for purge air (HAM1)
I added back the channels that I removed when the end X Beckhoff PLC2 went haywire yesterday. H1:ALS-X_SPARE_A_DEMOD_RFMAX H1:ALS-X_SPARE_B_DEMOD_RFMAX H1:LSC-X_TR_A_DC_RESPONSIVITY
I checked the BS oplev laser this morning and sure enough, as per Keita's aLOG here, the laser was going bad and in need of replacement. I watched the current monitor on the laser with a voltmeter (the monitor outputs a voltage) and ever 70'ish seconds it would drop from the set 0.760 V to 0.743 V. This laser was replaced with one from the EE lab fresh off an install of a DC to DC convertor board. This laser and its temporary DC power supply were installed between BSC2 and BSC3, on the East side. I tried to hide the power supply as much as I could to protect from accidental damage but it is large, so for anyone working in that area, please watch your feet. After installation I watched the current monitor and didn't see any drops as was seen with the previous laser.
in attendance: Jeff B, R Mc, Keita, Sudarshan, Jason, Jim W, Justin, Aaron, P King
OpLev - SR3 OpLev finished intitial calibration. The goal now is to get everything up and running for commisioning and addressing issues later. Keita addressed some erratic behaviour in the corner BSC OpLevs.
Vacuum - Hugh moving valve replacement at End-X 'up' due to the convenience of the upcoming Labor Day holiday
~Have a Great Labor Day Holiday~
What vacuum activity is Hugh doing at X-end?
Replacing a Parker valve.
Hepi - not vacuum.
[Dan, Nic, Koji]
After we tamed the OMC QPD spot motions by the alignment servo, we turned on the high voltage supply
as the vacuum pressure allowed to do that.
Then we did notice that the OMC is already locked. WHAT? Did we miss the most exciting moment!?
Well, it was okay. It was a higher order mode. We shifted the PZT offset and locked at the highest peak that gave
us about 13mA total current.
We went down to LVEA and checked the mode shape. Yes. It was TEM00.
The position of the OMC trans spot was checked at ISCT6. Unfortunately the spot was hitting a pillar of the ISCT6 enclosure.
It is not nice to make a hole on the pillar. We probably need to move the table and think carefully how to connect the tube
to the table enclosure...
The OMC REFL with the best alignment looked a bull's eye as we suspected (attached photo #1). Dan is now measuring the mode scan for the mode matching ratio.
For the celebration, Nic cut open an OMC locking cantaloupe. Thanks Gerardo!
Title: gains moved around in OMC servo
The OMC NORM output was not ~1.0, this was because the input to the normalization was less than 0.1, and the denominator has a lower saturation at that point.
I put a gain of 10 into 'H1:OMC-DCPD_NORM_FILT_GAIN' and 'H1:OMC-DCPD_NORM_GAIN'. Thus bringing the denominator above 0.1 and allowing the normalization to work. There was a gain of 1000 in 'H1:OMC-DCPD_NORM_GAIN' which I moved into 'FM8' of 'H1:OMC-LSC_SERVO' (called 60dB).
Finally, the gain change due to the normalization fix had to be corrected by putting a gain of 1 into 'H1:OMC-LSC_SERVO_GAIN'.
Old pictures.
Here are images of a mode-scan of the OMC, and spectra that show the control signal, the normalized DCPD Sum (called DCPD Norm, in units of RIN), and coherence between some interesting channels. The noise on the DCPDs is limited by the OMC, not the intensity noise from the IFO; only a little bit of the noise on IMC_TRANS is making it to the DCPDs. Note that the ISS is currently disabled. The two DCPDs are coherent so we're not shot-noise limited.
I took 60-second averages of the sum of OMCR_A with the OMC locked and unlocked. Unlocked the sum was 9316.68, locked was 1834.33. The visibility/mode-matching into the OMC is about 80%. (A small but nonzero fraction of this is due to the power in the sidebands, the modulation depth is 0.3.)
A text file for the mode scan can be found here. The columns are [time, PZT_VMON, DCPD_SUM].
Note, all of this data was taken with a single bounce off ITMX., with one stage of whitening on the DCPDs.
Also I've attached a figure of the OMC open-loop gain measurement. UGF is 90Hz.
Nice!
A few things in reply to Dan's comment:
1) I wonder why the mode scan looks so messy. Ramping the PZT over the full range should deform the cavity slightly, so we usually see a couple-percent difference in transmission from mode to mode, but the variation seems much wider here. Was the alignment not stable? Also, what's going on with those PZT readback saturations?
2) Was this RIN plot from before the NORM calibration was fixed? If not, it seems crazy high. It looks like your input beam is pretty noisy, since you see some coherence with IMC TRANS, but I guess this is somewhat expected at lower frequencies with ISS off. However, there is no way the OMC should be adding noise at that level.
3) Now would be a good time to balance the DCPDs. I believe Keita made a precise measurement of the electronic TFs which can be used for frequency-dependent correction, and then Koji should have the responsivity numbers for the diodes. Those should take care of most of the difference, and then the rest can be done with the balance slider (we needed 0.6% gain bias at LLO). The easiest way to do this is to put an intensity modulation line in and cancel it in the NULL signal.
I believe this was done with a single bounce of ITMX.
ITMY had an oplev issue at the time as you can seen in https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13654
S. Karki The zeroing of Applied Geomechanics Tiltmeter is completed at ENDX and should be up and running. It was so off-scale, using a bubble-level and voltmeter did the trick to bring it down to reasonable level and after that I used the DTT to level it more.
Jeff, Krishna, Robert here is the calibrated (against seismometer) amplitude spectral density.
That doesnt look quite right. Lets debug via email. -Robert
SMA cables?