Laser Status:
PMC:
FSS:
ISS:
So I took spectra of this, saved some references, controlled down Stage2, brought it back up to the same state and the peak was gone. However, after a short time the peak started growing. Starting out at the Isolation boosts, I found that by disabling the boosts on the X & RY dofs, the peak reversed and started shrinking. It went down but there may be more dofs where this is coming in or the disturbance may come & go or grow and shrink because now I see the peak going up and then dropping down. The first plot shows the full peak (refs) and the currents are with the boosts disabled. The PEM MAG channel is also shown.
Fabrice suggests we likely have a broad area of marginal stability and this feature which doesn't look like the Main 60Hz harmonic according too Robert (looking at Mag channels) is just a symptom. It could be a DC motor that has locked here and maybe restarting a few things and it may go away but we need to fix the marginal stability if we can confirm it. We will run a TF when able to look at the MIMO loop and go from there.
I have added three stages of 1:0 antiwhitening filters for LSC_POP_A_RF9 I and Q and LSC_REFL_A_RF45 I and Q.
The following now all have three such 1:0 filters:
Not that this can't be operator error but see attached. Jim noticed a large output from the ITMX Stage2. 1000s of counts is of concern; 100s is normal. Anyway, looking at dataviewer of the fast channels, I thought this was ~8Hz; but the spectum and the DTT time series says this is 120Hz. Still looking for this peak source.
OK Robert solved my problem--The Dataviewer by default comes up at 128 hz resolution and this 120Hz peak is very large. When I go to a higher 'resolution' in dataviewer it looks correct. User beware.
I am done with the morning red locking.
Status of the interferometer:
PRMI doesn't lock
I have no luck for locking the PRMI this morning -- I was never able to catch a fringe even for a short period of time for some reason. The alignment seemed OK because I could see a build up of about 10000 counts at maximum in POPAIR_B_RF18_I_ERR. I only tried the demod phase of 133 deg in REFLAIR_45. I didn't try to change the LSC gains at all because I ran out the time. Also, all the settings were once set by Stefan's old script, setPRMI, instead of guardian's up-script and then I changed the MICH and PRCL gains to be 40 and -0.4 respectively.
HAM3 ISI was found to be down. So I brought it up with the level 3 isolation as noted by Hugo (alog 10114). According to its watchdog medm screen, it tripped because the payload had tripped at 1076806396 (which corresponds to Feb 19 2014 00:53:00 UTC).
Until the blue team starts working on the WFS.
Also, I disabled the oplev damping loop to avoid unnecessary kick because the oplev beam is almost off from its QPD. I did the following commands:
ezcaswitch H1:SUS-ETMX_L2_OLDAMP_Y OUTPUT OFF
ezcaswitch H1:SUS-ETMX_L2_OLDAMP_P OUTPUT OFF
ETMX is back aligned for Keita and Jax who will do some EX WFS business. The oplev loops are also activated again.
I found that the LSC feedback was left on for the PRLC servo. This kept kicking PRM and PR2 without locking anything. Bad. I disabled it for now.
for some reason the ITMX ISI was using 750 blends, although Hugho left it on Tcrappy friday night (10114) and Hugh checked that things were OK this morning (10122.)
I moved it to Tcrappy on both stages
I was in a hurry; Jim was at the end station and sorely needed my assistance. Anyway, despite several attempts, I was unable to transition either ITM to lower blends with the trilliums. Oddly, the BS went fairly easily...
The IR path on ISCEX must have gotten misalinged, I tuned up the beat note and now we have -13.5dBm reported by the PFD.
Running from opsws0. Should finish by the morning meeting. It's very windy right now, so we may not get anything useful out.
I misaligned the BS and ITMX and looked at the trended time series of REFLAIR_A_RF45_Q_ERR. Since the beam is (in theory) bouncing prompty off the PRM and onto the diode without any kind of Fabry-Perot interference, this signal should tell us something about 45 MHz RFAM.
The calibration (7.6 cts / nm) is from elog 10127.
As Kiwamu pointed out, the calibration must be multiplied by R_PRM / T_PRM^2, since the PD experiences the reflection of PRM rather than the doubly-transmitted beam. The plot is now corrected.
We used AM laser to check up the ALSX WFS.
AM laser output: 1.8mW (measured with old ophir power meter, 978nm, filterr out)
Modulation source was set to 0.1vpp 24.389310MHz (this frequency was set before fixing the 1.002MHz that was mentioned in another alog).
WFS DC interface was set to low DC gain mode and the DC offset zero-ed.
Demod whitening gain was 21dB, first and the second whitening filter were on and the third off, a-whites were turned on though I don't know if they're put in yet (turns out that the awhites were not yet there when we did this measurement, so the "demod" numbers in the table below are 33dB higher than they should be.).
WFSA DC | WFSA demod (both I and Q) | WFSB DC | WFSB demod (both I and Q) | |
SEG1 | 3000 cts | +-20k cts | 2600 | +-19k |
SEG2 | 3070 | +-20k | 2900 | +-9k |
SEG3 | 2395 | +-12k | 2740 | +-20k |
SEG4 | 2930 | +-18k | 2960 | +-20k |
Seems like the demod signal out of WFSA SEG3 and WFSB SEG2 are both about a factor of 2 smaller than the others. On the scope it seemed that the RF signal coming from the WFS head was already small for these segments.
We confirmed that the whitening gain and filters are working.
Jax found that depending on how the cables were strained on the AM laser the amplitude of AM varies greatly (from nothingness to full). Crappy RF connection?
I didn't see such an effect when I used it at ISCT1 a month ago and the AM power was reproducable. This could be a new issue.
There may have been a miscommunication between me and Keita. When the cables were strained, they applied a torque to the laser, twisting it out of alignment with the WFS aperture (maybe 45 degrees rather than head-on? didn't exactly measure it, just corrected it.) So the power level issues were caused by cable strain, but on a purely mechanical level.
Working on unlocking SR2 suspension.
Andres and I are done. We unlocked the suspension, which seems to be free when looking at the L to L TF.