When PRMI is locked on REFL 165 I&Q signals MICH rms is dominated by the 60 Hz line and harmonics. It comes from demodulation board.

To increase SNR ZFL-100 LN amplifier (+23.5dB) was installed in LSC analog rack. MICH 60 Hz and harmonics are improved as shown on the plot "mich_err"

I have also added a few resg at low frequencies. MICH rms is not 3*10^-10. In Optickle I simulated power dependence in PRC and ARMs on MICH motion. Plot is attached.

 I think we need to stabilize MICH even more, down to ~3*10^-11 . We can think about increasing RF amplifier gain, modulation index and power on BB PD.

CARM offset reduction was a little better today due to improved MICH RMS. Power in arms increases up to 15 and than starts to oscillate up to 70 and then PRMI looses lock.

Tomorrow we need to discuss where to put RF amplifier. Current design has several drawbacks:

• DC power for the amplifier is wired from a custom (not rack based) +15V power supply that was already inside the lsc rack and used for other ZFL-100LN
• BNC cables are used because I could not find any long SMA cables
• we would like gain of ~40 dB instead of 23.5 dB

Last week, while I had the PRMI locked on REFL33, I did some poking around with mirror excitation to RFPD quadrature transfer functions. I got some indication of weird things with sensing MICH with the 3F REFL signals, but it should be explored more before taken as a real thing. I just figured I would show what I saw. 

With that disclaimer out of the way, here's what I did:

• Locked PRMI on PRCL:REFL33_I and MICH:REFL33_Q, as detailed in my earlier ELOG
• Created PRCL and MICH excitations at two different frequencies, notched said frequencies out of the control filters
• Took transfer functions from mirror LSC output signals to 33 I, 33 Q, 165 I, 165 Q in DTT
• For each DOF, look at the measured transfer functions only at the excitation frequency. (Assuming good coherence, which was there)

The basic idea was, some PRCL motion (for instance), has a transfer function to both the I and Q quadratures at a given PD. As the PRCL excitation sine wave goes through one cycle, the REFL signals at the excitation frequency go through some coherent cycle. Thus, the excitation traces out some trajectory in the I vs. Q plane. I believe this is analogous to the typical "radar plot" that we make for sensing matrix elements. 

However, the straight line that we normally plot in the radar plots assumes a certain phase relationship between the DOF-> I and DOF->Q transfer functions that results in a straight line. Here are the trajectories I actually measured, normalized by the excitation amplitudes.

The plotted traces are (x,y) = (H_prcl->I * prcl, H_prcl->Q * prcl) and  (x,y) = (H_mich->I * mich, H_mich->Q * mich) where H_prcl->I is the measured complex transfer function from prcl to REFL I, for instance, and prcl and mich are the excitation signals, normalized to unit amplitude.

PRCL looks like a nice straight line in both of these, and pretty well phased, but not only is MICH not very orthogonal to PRCL, there is quite a bit of ellipticity present, which means we can't fully decouple the two DOFs, even if they were nominally orthogonal. 

I'm not sure what may cause this. To back up this measurement/interpretation, I tried to take measurements of these transfer functions across different excitation frequencies via swept sine DTT, but seismic activity kept me from staying locked long enough...

I guess that you get an ellipse when the transfer functions to I and Q have a different phase. One mechanism could be that when driving MICH we make some residual PRCL and this couples with a different transfer function to both I and Q. However, I would expect no phase lag in the PRMI configuration, since there is no enough optical delay in the system to give significant dephasing at few hundreds Hz. This effect might come from mechanical resonances.

It is worth measuring the optical transfer functions from both PRCL and MICH to REFL signals at all frequencies, to see if we have strange features in the TFs.

Gabriele's PRCL/MICH reconstruction neural network is now running on c1lsc.  Summary:

• front-end model is called c1dnn, and is running as an experimental user-space process
• c1dnn is getting most of it's needed inputs from existing SHMEM IPC outputs from c1lsc
• none of the output signals from the network are being sent anywhere yet (grounded)
• c1dnn has not been integrated in any way, into the DAQ etc.  it is being run manually by hand, and will be completely shut down after this test

Simple MEDM screen I made to monitor the input/output signals:

The RTS process seems to run fine, but there is quite a bit of jitter in the CPU_METER, at the 50% level:

It's not running over the limit, but it is jumping around more than I think it should be.  Will look into that...

cpuset for cpu isolation for user-space model

The c1dnn model is running on CPU6 on c1lsc.  CPU6 was isolated from the rest of the system using cpuset.  The "cset" utility was used to create a "system" CPU set that was assigned to CPU0, and the kernel was instructed to move all running processes to that set:

controls@c1lsc:~ 2$ sudo cset set
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0,6 y       0 y   343    0 /
controls@c1lsc:~ 0$ sudo cset set -c 0 -s system --cpu_exclusive
cset: --> created cpuset "system"
controls@c1lsc:~ 0$ sudo cset set
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0,6 y       0 y   342    1 /
       system          0 y       0 n     0    0 /system
controls@c1lsc:~ 0$ sudo cset proc --move -f root -t system -k
cset: moving all tasks from root to /system
cset: moving 292 userspace tasks to /system
cset: moving 0 kernel threads to: /system
cset: --> not moving 50 threads (not unbound, use --force)
[==================================================]%
cset: done
controls@c1lsc:~ 0$ sudo cset set
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0,6 y       0 y    50    1 /
       system          0 y       0 n   292    0 /system
controls@c1lsc:~ 0$ sudo cset proc --move -f root -t system -k --force
cset: moving all tasks from root to /system
cset: moving 50 kernel threads to: /system
[==================================================]%
cset: **> 29 tasks are not movable, impossible to move
cset: done
controls@c1lsc:~ 0$ sudo cset set
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0,6 y       0 y    29    1 /
       system          0 y       0 n   313    0 /system
controls@c1lsc:~ 0$

I then created a set for the RTS process ("rts-c1dnn") on CPU6, and executed the c1dnn model in that set:

controls@c1lsc:~ 0$ sudo cset set -c 6 -s rts-c1dnn --cpu_exclusive
cset: --> created cpuset "rts-c1dnn"
controls@c1lsc:~ 0$ sudo cset set
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0,6 y       0 y    24    2 /
    rts-c1dnn          6 y       0 n     0    0 /rts-c1dnn
       system          0 y       0 n   340    0 /system
controls@c1lsc:~ 0$ sudo cset proc -s rts-c1dnn --exec /opt/rtcds/caltech/c1/target/c1dnn/bin/c1dnn -- -m c1dnn
cset: --> last message, executed args into cpuset "/rts-c1dnn", new pid is: 27572
sysname = c1dnn
....

When done I just hit Ctrl-C.

I left the cpusets as they are, with all system processes in the "system" set.  This should not pose any problems since it's the identical configuration as would be if a normal kernel-level model was running in CPU6.

The c1dnn process and it's EPICS sequencer were shutdown after this test.

The MICH actuation with PRM/BS was investigated again.

(ITMX -1 / ITMY +1) is equivalent to (PRM -0.267 and BS +0.50).

- PRMIsb was locked with REFL33I&AS55Q.

- Using the locking module in the LSC model, actuate ITMX (-1) and ITMY (+1) at 580.1Hz. Note that the notch filters in the MICH/PRCL servos were on.

- Look at the peak in the AS55Q spectrum. Tune the BS element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at BS = -0.50.

- Look at the peak in the REFL33I spectrum. Tune the PRM element in the output matrix of the lock-in to minimize the peak height.
=> The peak was minimized at PRM = +0.267

- These measurement leads to the conclusion mentioned above.

Koji is elogging separately of his exploration of different configurations.  The lock stretch that I'm looking at here uses the same parameters as Koji had for PRMI sb lock, using AS55Q for MICH and REFL33I for PRCL, with MICH gain of -0.8 and PRCL gain of 0.05 .

All of these plots are the same few second lock stretch, with different zooming.  Jamie's super-sweet getdata python script only accepts integers for the start time and duration parameters, so lots of this zooming happened by hand, but I tried to always keep the time axis aligned within each screenshot.  Sometimes the plot axis labels say differently, but they're lying to you.

Plot 1:  gps start time is 1050915916, duration = 6 seconds.  Overall view of the lock stretch.

Plot 2:  gps start time is 1050915921, duration = 1 second.  We're looking at the lockloss that happens at the left side of the plots.

Plot 3:  zoomed in (along the time-axis) version of plot 2, so much shorter time duration.  Some zooming on y-axes.

Plot 4:  zoomed in (along y-axes) version of plot 2.

It seems to me from these plots that maybe MICH CTRL is drifting away?  It seems like we lose the MICH lock, and that destroys the whole thing. 

Koji made some comments to me earlier, regarding his work this evening, that the MICH signal quality is poor in general, and that we should calculate/think about changing our schnupp asymmetry. 

Last night I performed some MISO FF on MCL using the T240-X and T240-Y as witnesses. Here are the results:

Filter:

T240-X

T240-Y

Training data + Predicted FIR and IIR subtraction:

Online subtraction results:

MCL

YARM

Subtraction performace:

I decided to give MISO Wiener filtering a try again. This time around I managed to get working filters. The overall performance of these MISO filters is much better than the SISO I constructed on elog:11541 .

The procedure I used to develope the SISO filters did not work well for the construction of these MISO filters. I found a way, even more systematic than what I had before to work around Vectfit's annoyances and get the filters in working condition. I'll explain it in another eLOG post.

Anyways, here are the MISO filters for MCL using the T240-X and T240-Y as witnesses:

 Now the theoretical offline prediction:

The online subtractions for MCL, YARM and XARM. I show the SISO subtraction for reference.

 And the subtraction performance:

MISO Wiener filters for MCL kept the mode cleaner locked for a good 8+ hours.

We computed the required actuation range for the telescope design in elog:15357. The result is summarized in the table below. Here we assume we misalign an IFO mirror by 1 urad, and then compute how many urad do we need to move the (AS1, AS4) or (LO1, LO2) mirrors to simultaneously correct for the two gouy phases. 

The most demanding ifo mirrors are the ETMs and the BS, for every 1 urad misalignment the telescope needs to move 10-15 urad to correct for that. However, it is unlikely for those mirrors to move more 100 nrad for a locked ifo with ASC engaged. Thus a few urad actuation should be sufficient. For the recycling mirrors, every 1 urad misalignment also requires ~ 1 urad actuation. 

As a result, if we could afford 10 urad actuation range for each telescope suspension, then the gouy phase separations we have should be fine. 

================================================================

Edits:

We looked at the oplev spectra from gps 1274418500 for 512 sec. This should be a period when the ifo was locked in the PRFPMI state according to elog:15348. We just focused on the yaw data for now. Please see the attached plots. The solid traces are for the ASD, and the dotted ones are the cumulative rms. The total rms for each mirror is also shown in the legend. 

I am now confused... The ITMs looked somewhat reasonable in that at least the < 1 Hz motion was suppressed. The total rms is ~ 0.1 urad, which was what I would expect naively (~ x100 times worse than aLIGO). 

There seems to be no low-freq suppression on the ETMs though... Is there no arm ASC at the moment???

I don't think we ever discussed why the angular RMS of the ETMs is so much higher than the ITMs. Maybe that's a separate matter because, even assuming the worst case, the actuation range requirement is

(0.82 μrad RMS) x (15 μrad/μrad) x (10 safety factor) = 0.12 mrad

which is still only order 1% of the pitch/yaw pointing range of the Small Optic Suspensions, according to P1600178 (sec. IV. A). Can we check this requirement off the list?

After using alamode to calculate the round-trip mode of the beam at the Faraday exit after retro-reflection form the PRM, I'm not able to blame the MMT and TT curvature for the beam ellipticity.

I assume an input waist at the mode cleaner of [0.00159, 0.00151] (in [T, S]).  Propagating this through the MMT to PRM, then retro-reflecting back with flat TTs I get

w_t/w_s = 0.9955,  e = 0.0045

If I give the TTs a -600 m curvature, I get:

w_t/w_s = 1.0419,  e = 0.0402

That's just a 4% ellipticity, which is certainly less than we see.  I would have to crank up the TT curvature to -100m or so to see an ellipticity of 20%.  We're seeing something that looks bigger than 50% to me.

Below are beam size through MMT + PRM retro-reflection, TT RoC = -600m:

We removed the Lightwave MOPA Controller, PA#102, NPRO206 power supply to make room for the IOO chassy at 1X1 (south) rack.

The umbilical cord was a real pain to take out. It is shading its plastic cover. The unused Minco was disconnected and removed.

The ref. cavity ion pump controller- power supply was temporarily taken out also.

I fixed the broken slider to change the current of the PA.

The problem was that the EPICS database assigned a wrong channel of the DAC to the slider.

I found that the PA current adjustment signal lines are connected to the CH3 &CH4 of VMIC4116 #1. However in the database file (/cvs/cds/caltech/target/c1psl/psl.db), the slider channel (C1:PSL-126MOPA_DCAMP) was assigned to CH2. I fixed the database file and rebooted c1psl. Then the PA current started to follow the slider value.

I moved the slider back and forth by +/-0.3V while the ISS loop was on. I observed that the amount of the low frequency fluctuation of the MOPA power changed with the slider position. At some current levels, the ISS instability problem went away.

Kakeru is now taking open-loop TFs and current shunt responses at different slider settings.

 I have updated the PSL Diagram wiki page to include MOPA. As with the PSL diagram, clicking the photo on the main page takes you to a larger image. The inventory is pretty meager as I didn't have time to sit and read labels (if indeed there are any). I will look through the documentation at the 40m to see if there is a record of what is there. Again, if you know something, please amend the list!!

http://lhocds.ligo-wa.caltech.edu:8000/40m/PSL_Table_Diagram

Not dead. It just had a HT fault. You can tell by reading the front panel. Cycling the power usually fixes this.

MOPA is back onliine.  Rana found that the fuse in the AC power connector's fuse had blown.  This was evident by smelling all of the inputs and outputs of the MOPA controller. The power cord we were using for this was only rated for 10A and therefore was a safety hazard. The fuse should be rated to blow before the power cord catches on fire. The power cord end was slightly melted. I don't know why it hadn't failed in the last 12 years, but I guess the MOPA was drawing a lot of extra current for the DTEC or something due to the high temperature of the head.

We got some new fuses from Todd @ Downs. 

The ones we got however were fast-blow, and that's what we want  The fuses are 10A, 250V.  The fuses are ~.08 inches long, 0.2 inches in diameter. 

I found the laser dead this morning.

The crane people are here to unjam it.

Laser hazard mode is lifted and LASER SAFE MODE is in place. No safety glasses but CRANE HAZARD is still active.

Stay out of the 40m lab !

steve, rob, alberto

Steve installed two rotary flow meters into the MOPA chiller system--one at the chiller flow output and one in the NPRO cooling line.  After some hijinks, we discovered that the long, insulated chiller lines have the same labels at each end.  This means that if you match up the labels at the chiller end, at the MOPA end you need switch labels: out goes to in and vice-versa.  This means that, indubitably, we have at some point had the flow going backwards through the MOPA, though I'm not sure if that would make much of a difference. 

Steve also installed a new needle valve in the NPRO cooling line, which works as expected as confirmed by the flow meter. 

We also re-discovered that the 40m procedures manual contains an error.  To turn on the chiller in the MOPA start-up process, you have to press ON, then RS-232, then ENTER.  The proc man says ON, RS-232, RUN/STOP.

The laser power is at 1.5W and climbing.

 Rob, Alberto

The chiller HT alarm started blinking, as the water temperature had reached 40 degrees C, and was still rising.  We turned off the MOPA and the chiller.  Maybe we need to open the needle valve a bit more?  Or maybe the flow needs to be reversed?  The labels on the MOPA are backwards?

The MOPA is taking the long weekend off.

Steve went out to wipe off the condensation inside the MOPA and found beads of water inside the NPRO box, perilously close to the PCB board.  He then measured the water temperature at the chiller head, which is 6C.  We decided to "reboot" the MOPA/chiller combo, on the off chance that would get things synced up.  Upon turning off the MOPA, the neslab chiller display immediately started displaying the correct temperature--about 6C.  The 22C number must come from the MOPA controller.  We thus tentatively narrowed down the possible space of problems to: broken MOPA controller and/or clog in the cooling line going to the power amplifier.  We decided to leave the MOPA off for the weekend, and start plumbing on Tuesday.  It is of course possible that the controller is the problem, but we think leaving the laser off over the weekend is the best course of action.

MOPAs and their settings, powers of 7 years in the 40m

In today's ISC call, Kiwamu was comparing two ways to approach resonance: 

• "C-Type": The scheme we currently think about; zero DARM offset and slowly reduce the CARM offset
• "D-Type": Start with no CARM offset, but a DARM offset and reduce that. 

D-type might be interesting to check out, since things change a little less dramatically when you reduce the DARM offset. Maybe this makes signal hopping easier? Signal recycling may complicate things, though. 

So, I've simulated CARM and DARM offset effects on CARM and DARM signals. (As with the previous plots, this is for the PRFPMI configuration.) From moving both offsets around, it looks like the resonance peak is about 5x wider in DARM than in CARM, so I simulated a 50pm offset range for CARM and a 250pm offset range for DARM. 

Here are some CARM signal transfer functions subject to CARM offsets in the top plot, and DARM offsets in the bottom plot. 

It's looks like the DARM offset changes cause much less dramatic changes in the CARM plant features. It's conceivable that this would make CARM locking easier. 

Here are some DARM plant transfer functions. 

In these plots, I did something kind of artificial: when we move the CARM offset, it changes the proper demodulation phase to get DARM in the Q of the AS 1F RFPDS. So, at each CARM offset, I re-phased the AS 1F demodulators, to show the total DARM information available at the AS RFPDs at each offset, rather than what one would actually see in them with a static demod phase. 

Since python from crontab seemed intractable, I replaced autoMX.py with a soft link that points at autoMX.sh.

This is a simple BASH script that looks at the LSC FB stat (C1:DAQ-DC0_C1LSC_STATUS), and runs the restart mxstream script if its non-zero.

So far its run 5 times successfully. I guess this is good enough for now. Later on, someone ought to make it loop over other FE, but this ought to catch 99% of the FB issues.

AutoMX is resetting mx_stream every 5 minutes. Basically everytime AutoMX is called,
it resets mx_stream. Is the mx_stream stalling such often? Or the script is detecting false alerms?

> tail -200 /opt/rtcds/caltech/c1/scripts/cds/autoMX.log

Tue May 19 16:43:01 PDT 2015
LSC - FB bad. Runnning restart:
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1sus closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1lsc closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1ioo closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscex closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscey closed.
0
Tue May 19 16:48:02 PDT 2015
LSC - FB bad. Runnning restart:
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1sus closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1lsc closed.
ssh_exchange_identification: read: Connection reset by peer
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscex closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscey closed.
0
Tue May 19 16:53:01 PDT 2015
LSC - FB bad. Runnning restart:
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1sus closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1lsc closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1ioo closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscex closed.
 * Stopping mx_stream ...                                                 [ ok ]
 * Starting mx_stream ...                                                 [ ok ]
Connection to c1iscey closed.

Good catch; that was some seriously bad programming on my part. I had some undeclared variable garbage going on. I fixed it and re-implemented the script in CRON on megatron. The log file shows that it has detected no problems for the last several checks. I'll check it again tomorrow to see if its doing good or bad.

In the future, mirrors shouldn't be so close together that you can't get at their knobs to adjust them No good.  I ended up blocking the beam coming out of the PMC to prevent sticking my hand in some beam, making the adjustment, then removing the dump.  It worked in a safe way, but it was obnoxious. 

- we finished the MZ alignment; the contrast is good.

- we did the RFAM tuning using a new technique: a bubble balanced analyzer cube and the StochMon RFPD. This techniques worked well and there's basically no 33 or 166 RFAM. The 133 and 199 are as expected.

- the MC locked right up and then we used the periscope to align to it; the transmission was ~75% of max before periscope tuning. So the beam pointing after the MC should be fine now.

- the Xarm locked up with TRX = 0.97 (no xarm alignment).

If Rob/Yoichi say the alignment is now good, the we absolutely must center the IOO QPDs and IP POS and IP ANG and MC TRANS  today so that we have good references.

-----------------------------------

The first photo is of our nifty new setup to get the beam to the StochMon PD.  The MZ transmitted beam enters the photo from the bottom right corner, and hits the PBS (which we leveled using a bubble level).  The P-polarization light is transmitted through the cube, and the S-polarization is reflected to the left.  The pure S-polarized light hits a Beam Splitter, which we are using as a pickoff to reduce the amount of light which gets to the PD.  Most of the light is dumped on an aluminum dump.  The remaining light hits a steering mirror (Y1 45-S), goes through a lens, and then hits the StochMon PD.  While aligning the MZ to maximize visibility, we look at the small amount of P-polarized light which passes through the PBS on an IR card, and minimize it (since we want to be sending purely S-polarized light through the EOMs and into the MC).

The second photo is of a spectrum analyzer which is directly connected to the RF out of the StochMon PD.  To minimize the 33MHz and 166MHz peaks, we adjust the waveplates before each of the EOMs, and also adjusted the tilt of the EOM holders.

The final photo is of the EOMs themselves with the Olympus camera.

Once we finished all of our MZ aligning, we noticed that the beam input to the MC wasn't perfect, so Rana adjusted the lower periscope mirror to get the pointing a little better.  

The MZ refl is now at 0.300 when locked.  When Rana reduced the modulation depth, the MZ refl was about 0.050 .  Awesome!

C1:PSL-MZ_MZTRANSPD

I will investigate the MZ board. I will unlock MZ (and MC).

I aligned the MZ.  The reflection went from .86 to .374

I think the MZ pzt is broken/failing.  I'm not sure how else to explain this behavior.

The first bit of the time series is a triangle wave into the DC offset (output) field, over approximately the whole range (0-250V).   You can see the fringe visbility is quite small.  The triangle wave is stopped, and I then maxed out the offset slider to get to the "high" power point from the triangle wave sweep. Then for a little while with the PZT is held still, and the power still increases.  The MZ is then locked, and you can see the PZT voltage stay about the same but the power continues to rise over the next ~10 minutes or so.

This plot answers the previous question, and raises a new one--what the heck is MZTRANSPD?  I'd guess the pins are unconnected--it's just floating, and somehow picking up the MZ_PZT signal.

Came back from dinner to find the Mach Zehnder unlocked.  The poor IFO is kind of having a crappy day (computers, MZ, and I think the Mode Cleaner alignment might be bad too).