H1 PSL Operator Check

Laser Status:

• Outpout Power = 28.9W (should be ~30W, 1yr trend of power attached)
• Watchdog ACTIVE
• SYSSTAT screen was mostly GOOD, except for some RED flashing of the Head 1-4 Flow (channel = H1:PSL-OSC_LOWFLOW).  This channel was RED from 11:06-11:13am (see attached).  VB program online is RED as usual.

PMC:

• Locked for a little over a 1 day
• PMC Reflected Power (1.1W) is a little over 10.2% of Transmitted Power (10.8W)....it should be under 10%

FSS:

• Locked only 6+hrs ago
• Alignment looks good on the RefCav Trans video
• Trans PD DC Output = 0.930 V  (should be 0.9V)

ISS:

• AOM Diffreacted Power = 6.4% (should be 10%)
• Last Saturation Event = 18hrs ago (should be days to weeks)

ITMX 120[.4]Hz peak

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.

Antiwhitening filters for LSC PDs

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:

• LSC_POP_A_RF9 I and Q
• LSC_POP_A_RF45 I and Q
• LSC_POPAIR_A_RF9 I and Q
• LSC_POPAIR_A_RF45 I and Q
• LSC_POPAIR_B_RF18 I and Q
• LSC_POPAIR_B_RF90 I and Q
• LSC_REFL_A_RF9 I and Q
• LSC_REFL_A_RF45 I and Q
• LSC_REFLAIR_A_RF9 I and Q
• LSC_REFLAIR_A_RF45 I and Q
• LSC_REFLAIR_B_RF27 I and Q
• LSC_REFLAIR_B_RF135 I and Q

Using Dataviewer for frequency analysis--Beware

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.

done with the morning red lock

I am done with the morning red locking.

Status of the interferometer:

• ETMX is aligned for the green WFS work.
• BS, which had been misaligned, is now aligned.
• PRMI-related optics are all left aligned. It is still fringing. Feel free to misalign if necessary.

 

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.

Arm modulation frequency

After finding that we weren't able to stably lock the arm cavity with the half Anderson modulation frequency, we switched it back to the rf source 24.407079MHz. I used the 4392A to confirm that there is about 0.1 dBm going to the eom

PRMI guardian not accessible

Help me, Jamie! I want to use LSC_PRMIsb!

HAM3 ISI is back to business

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).

ETMX intentionally misaligned

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

feedback left on PRM and PR2

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.

ITMX ISI

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

end x PLL beat note realinged

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. 

REFLAIR_A_RF45_Q_ERR RFAM

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.

ALSX WFS RF check (Yuta, Jax, Keita)

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.).

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.

Arnaud at HAM4 @ 1:28 PM PT

Working on unlocking SR2 suspension. 

Michelson lock adjustments and measurements

[Yuta, Rana, Evan]

When Stefan left Friday evening, PRMI wouldn't lock. We poked around at MEDM screens for a while before deciding that a more systematic diagnosis was in order. We decided to attack just the Michelson first.

We parked PRM and misaligned ETMX. We then adjusted the LSC MICH filter bank to duplicate was was done for Kiwamu's and Yuta's previous Michelson lock characterization (elog 9698, 31 Jan 2014). Even with a 1:0 integrator engaged, we found that the Michelson would not lock for more than 30 s, and the error signal drifted by about a third of its peak-to-peak.

We were able to measure the OLTF, and found that it had a UGF of 3 Hz with no phase margin. Rana suggested we notch out the bounce mode of the BS suspension with filters from LLO. We got the filter, adjusted the frequency to the LHO BS (17.8 Hz, as measured from the REFLAIR_A_RF45_Q_ERR spectrum), and then added it to FM6 on LSC_MICH. After doing this, we found that the Michelson lock is much more stable --- it appears to lock indefinitely.

In order to calibrate REFLAIR_A_RF45_Q_ERR in terms of mirror motion, we let the Michelson swing freely and recorded the fringing. We know that the fringing amplitude (in counts) as a function of asymmetry l is A sin(4 pi l / lambda), so the linear portion has a slope of A * 4 pi / lambda, in counts per m. I took the swinging data, trended the minimum, median, and maximum, and then took the median of the trended minimum and maximum values. A histogram of these values is attached. From this I find A = 643 counts; this gives the conversion factor as 7.6 counts per nanometer.

We used this value to get a calibrated spectrum of the dark noise of REFLAIR_A_RF45_Q_ERR, which we measured with the modecleaner unlocked. A trended 10-minute time series is attached; we see that the drift is on the order of a few nanometers over this time period. Also attached is a spectrum of the dark noise, along with Yuta's estimate of the control signal (LSC_MICH_OUT) the Michelson, given in terms of length. The estimated length noise was 1.1 um RMS.

An OLTF of the improved Michelson loop is attached. The UGF is now 7.5 Hz, with a phase margin of 20 degrees. Also attached is Yuta's model of the expected OLTF; the agreeement is excellent around the UGF, except for the flat gain. This model uses already existing an already of the triple suspension of the BS (/ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/TripleModel_Production).

We assumed that the suspension model gives BS actuation efficiency from H1:SUS-BS_M2_LOCK_L_OUTPUT to the actual M3 motion in m/counts. However, there is a missing factor of 1.7e-3 in this actuation efficiency to fit to the measured OLTF.