On Wednesday (21st) night, I checked the AP table as I wanted to try PRMI locking.
It was difficult to work with the table as there were so many unnecessary components on it.
Also the beams went through complicated paths as they have funny angles.
So I decided to clean up of IMC REFl WFS, IFO REFL, and IFO AS paths.
I found that the AS beam was highly astigmatic as the beam went through a (too-much-) tilted lens.
I made several blocked optical paths for REFL and AS for future extension of the detection system.
The current status of the table was uploaded below.
The optical spectrum analyzers and the aux NPRO were left untouched but they should be moved
somewhere (either on the table or outside) which does not disturb the other optical paths.
After the cleaning, I started locking PRMI. I could lock PRMI stably. But I could not figure out how
the intra-cavity mode looked like as I did not have the POP camera. The power recycling
gain was not quantitatively evaluated as I did not have POP and I wasn't sure how the beam was aligned at POX/POY.
We need to know:
- Quantitative evaluation of the beam shape in the PRC
- Quantitative evaluation of the power recycling gain
Some obvious things to be fixed
- The POX whitening filters seem not switching. This issue should be checked at the circuit module itself and at the BIO.
- The POX beam is not well focused on the PD. This was particularly clear when PRMI was locked with carrier.
- The POP beam is going nowhere. We need POP55 and POP CCD for diagnoses.
I haven't checked ITMY table.
For the loop diagnosis, its best to use the method of "IN1/IN2", rather than manipulate the close loop gain. In this way, you can directly plot the swept sine measurement from DTT as the open loop gain.
Also, for reporting calibration, we should all try to record the current settings better. Anything that may change the loop gain should be recorded along with the Bode plot and the DATA must be posted to the elog - no more of just posting plots.
We need to know, e.g.
what is the power in the arms?
are the LSC whitening filters on?
are the SUS dewhitening filters on?
What normalization is being used in the LSC?
What digital filters are on in the X/YARM loop filter bank?
Resistance is feudal.
In order to estimate whether we can see acoustic coupling in arms or not, we have to calibrate signals to phase noise.
I used the same method as Yuta and Jenne did (6834).
I switched from ETM locking to ITM locking since only ITM actuators are calibrated (5583), and measured the open loop transfer function and the transfer function from ITM excitation to POX/POY error signal. Then I can estimate the calibration value H [counts/m] from POY/POX error signal to displacement.
Yarm; H = 9.51 x 1011 counts/m
Xarm; H = 6.68 x 1011 counts/m
Phase noise in arms:
blue; Xarm, green; Yarm
I will calibrate the acoustic signal and see if it is reasonable that we can see the acoustic coupling signal in the arms.
But I guess it is difficult. Actually I have not seen coherence between ETM feedback signals and acoustic sounds yet. (I measured acoustic noise near POX and in PSL table.)
If I find that it is hopeless, I will create some sounds and try to measure transfer function from acoustic sound to arm cavity signals.
I am interested in how the transfer function calculated by wiener filtering is different from the measured transfer function.
I found that we do not have enough phase margin. This is why the arm locking is not so stable.
As MCL is disturbing arm locking by injecting a lot of noise, I have modified 'mcup' to disable MCL
As MC WFS keeps failing to start up when it is locked, the lines in 'mcwfsoff' to clear WFS filter history were restored.
Since the transmission beam on ETMXT camera seemed to be clipped, we checked the optics on ETMX table.
We aligned the lens so that it is orthogonal to the beam, then the beam shape looks fine.
Also we removed some an-used optics which were used for fiber input.
Last night I found that the MC autolocker has not been updated since the chamber was closed.
i.e. The low power version had been used.
I logged into op340m and modified crontab via "crontab -e" so that the normal power version is spawned.
I got two seismometers and one microphone back from Tara.
They are now near the Gurlap under the MC.
If anybody wants a fancy single-axis seismometer for a while (GS-13), then please let me know.
New Lumitek IR Sensor Cards are here. We got 2 pieces of Q-11-T (2" x 2"), 2 pieces of Q-11-T (0.75" x 0.75") and one Q-11 (4" x 5")
We aligned and locked x and y arms.
MCL loop makes arms lock unstable, adds a lot of noise at frequencies 60-100 Hz. We'll fix it.
At some point we were not able to lock because of ADC overflows of PO signals. They happened if whitening filters were enabled. So we reduced the gain of POX whitening filters down to 36 dB and POY - to 39 dB. Now cavities can be locked with whitening filters.
Also we changed the pedestal of the lens in the beam path to the POX because the beam was too high.
Adjusted focus on ETMYF camera so that the IR beam is in focus.
For convenience, I would include a steering mirror in front of the TRX PD. Also, don't we usually have lenses in the oplev paths? Also, also, do we need lenses in front of the green refl and TRX PDs? Do you have a place in mind for the shutter? Is there a way to compactify the layout a little bit, so that even if the lenses are different for each table, the general layout for both ETMX and ETMY is the same (with an empty space on ETMX where IPANG belongs on ETMY)? I'm sure it is, since you've talked to Steve about this, but just to check: is the green refl PD far enough away from the edge of the table to accommodate the fancy new box?
I have attached the possible layout of the optics on the new ETMX endtable. More optics have been added when compared to the early cartoon layout considering that we need additional steering mirrors for reasons like: the table height in and out-of vac are different and several mounts have restricted movement in certain degrees of freedom.
As you can see, there is enough room for filters and other last time additions that may arise.
I will proceed with calculations based on the distances from the CAD drawing and the spec of the optics if there are no comments or suggestions about the layout.
Charles Blakemore our new undergrad help received 40m specific safety training today.
Oplev values that were changed to zero:
PRM P=0.15, Y=-0.3
SRM P=-2.0, Y=2.0
BS P=0.2, Y=-0.2
ITMY P=2.1, Y=-2.0
ITMX P=1.0, Y=-0.5
ETMX P=-0.2, Y=-0.2
ETMY P=0.5, Y=0.6
Also, PRCL was changed in the LSC input matrix from REFL33I to AS55I, since there is no REFL beam out of the IFO :(
Ayaka and I restored all of the oplev gains to these values. The exception is ETMY, which has both gains negative. I am unsure if this is a transcription error on my part, or if something physical has changed. The layout of the ETMY oplev was modified (since Rana took out the offending lens) but that shouldn't affect the sign of the gains.
POY11 does not go out of the vacuum
It does but slighty low and does not get on mirrors. We need to change optic mounts to adjust the height. Red is flashing in yarm at 00 and 10 modes. TRY is ~0.4-0.5.
I've adjusted BS angle, camera and TRX PD at ETMX table so I can see red flashing at 03 mode while green is locked to 00 and its transmission is maximized. I thought that by adjusting BS angle, I will be able to align red to 00 not disturbing green, but this was not the case. Maximum TRX I could get was 0.1. I've adjusted POX to get into PD and I can see PDH signal though I can't lock as cavity is still misaligned for red.
We put the POY beam onto the POY PD. The Yarm is currently locked on IR with ~0.65 transmission.
You have constraints for the IR beams (i.e. one PZT and one BS for 8 dofs), so now you need to align the arms for the input IR beams.
The PZT and BS should be aligned so that you have the beam spots as center as possible with the above restrictions.
Then realign end greens for the given arm alignment. You can replace the mounts if necessary to align the end green.
Even if you lose the coarse alignment of the green, realignment is not difficult as you know now
We aligned accurately 00 green in yarm, changed voltage on PZT2 to see red flashing at TRY at the normalized level 0.2-0.3. The plan was to lock yarm using POY11 and green from other side, maximize red TRY by adjusting PZT2. But POY11 does not go out of the vacuum, so we adjusted TRY by flashing. 2 DOFs of PZT2 is not enough to match 4 DOFs of red beam so we adjusted both PZT2 and cavity mirrors. TRY flashing is 0.5-0.6 and green is still locking to 00 though its transmission is not maximized. We'll fix it later by adjusting input green beam.
Next we wanted to get red beam on TRX PD. Beam steering was done by BS only. We misaligned BS in pitch and excited BS angle motion by 1000 counts. We could see red beam moving on the wall of ETMX chamber. We moved it to ETMX mirror frame, estimated position of the mirror center and moved BS to this position. The beam should be approximately in the middle. For now we can not see red beam on the camera at ETMX table, more work is needed.
We aligned and locked xarm for green.
That's really, really awesome!
People complained about the MC instability: If we aligned the MC, it locked nicely for a while.
Then suddenly you find that it got totally misaligned with the order of 0.2 with the alignment slider.
This misalignment usually happens for MC2, but it happend on MC3 once.
Surprisingly to me, this instability happened even without MCL and WFS, not only once but at least three times.
This suggests that the suspensions are the cause of the trouble.
I played with the MC2 suspension for a while in the afternoon. It seems that it has a hysteresis (or say, bistablity).
And the nominal alignment of MC2 seems close to the point where the transition happens. (Dunno why)
I further played with MC2 and found that a step of POS actuation by +/-10000 induces this transition go and back.
When the POS kick is in the negative direction (-10000), the MC2 seems to return to the preferrable
position. Therefore, I applied DC position force of -5000 to pull the mirror a bit from the nominal position.
I let the MC locked for ~4hours without MCL and WFS, it kept good alignment and the lock was stable
except for unlocks because of the activties by Den and Ayaka.
All of them has been done without previous monitor data as the tools were available.
The MC2 situation is not conclusive but we should check how we can prevent the bistable transition
by restricting MCL/WFS.
We aligned and locked Y arm for green:
I've switched error channel cable to output monitor. Whitening filter is need for scattering measurements.
I didn't make any concrete progress today. AS and REFL cameras are in place, and Manasa has put ND 0.5 filters on both. I used a
camera to look at the back of the Faraday, and aligned PRM such that it was retroreflecting, and then tried to align ITMY to have once
fringes with the PRM at that place. I failed in this, since the AS beam on the AS table was starting to dall off the first mirror on the table.
I then restored all the suspensions to where they were before I started touching them today.
I moved ETMY face camera so that it is looking at the front of the black glass, but it's hard to tell where the beam is. I was thinking
about setting up a temporary camera to look at the back of ITMY to help guide PZT steering, but I haven't done this yet.
Koji and I then talked about the several different options I have for references, and how many different knobs I can turn. I'm sleeping
on it for now, and hopefully I'll have more insight on what to do tomorrow.
I've applied LQR feedback technique to BS oplev in pitch. I think the most inconvenient thing in using LQR controller is the amount of additional states created during cost function shaping. It requires 1 filter bank for each state. To avoid this I wrote state estimation code so all states are calculated inside one function.
On the plots below cost function and oplev feedback controller performance are shown.
I tried to add a test point to C1MCS model and spent next two hours rebooting front-ends, restarting models and realigning MC.
dmesg told me that DAQ channels can not be allocated as they already exist. Last time we met this problem Jamie emailed Alex about it. Jamie, what is the output? Restarting iop model does not help this time.
We have discovered that the MCL loop squishes the length fluctuations that result from the MC spot measurement angular dither. This is good, in that the MCL is doing what it ought to do. However, we need to turn it off before doing a spot measurement.
This is totally non-sensical statement, of course.
We might also say that the DARM loop totally squishes the GW signal and so its better not to have any feedback in the interferometer.
Hmmm, indeed. To keep MC_L on, we should be looking at the control signal rather than the error signal. I think Den has MC_L running nicely such that it always comes on when the MC locks, so I can switch it.
WFS are back on, and working nicely. Den and I had seen a problem (which I had seen before) that when you turn on the integrators in the WFS loops, the MC Refl value gets worse (goes up). Koji reminded me that he had a nice elog (7452) on how to get the MC awesome. Ayaka and I last night stopped after Step 7. Step 8, zeroing the WFS offsets, is the secret important thing that I keep forgetting. I ran the script /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets, then turned on the WFS loop, and the WFS are working just fine now.
I'm back to wishing that I had control over PZT1. I went back and forth for a while between 1Y4 and the ETMY table to get the IPANG beam centered on the QPD. Initially, the beam was coming out of the vacuum a little high. The digital HV power supply is pitch, and the analog HV power supply is yaw. When I get the beam reasonably well centered on IPANG, with a beautiful, non-clipped, beam, the beam is much too high on IPPOS. The beam barely hits the top of the first out of vac steering mirror, and then is too high on the QPD. It looks like (based on the sum value) that the beam is on the diode, just entirely in the upper 2 quadrants. But if I try to fix this, since IPANG has a longer lever arm, the IPANG beam doesn't come out of the vacuum. I have compromised by getting the beam on IPANG, centered in pitch and ignoring IPPOS pitch. For yaw, since moving PZT2 only makes one of POS or ANG good at a time, I split the difference, so the beam is not really centered in yaw on either, but it's close on both.
AS beam is back on the camera. I forgot that, especially since the beam at REFL is pretty bright, I had moved the AS and REFL cameras out of the beam so we didn't crispy-fry the CCDs. Therefore, the camera spots are no longer a reference of spot position. We can still eyeball the position on, say, the 2" lens, but that's not any kind of accurate. I put the AS camera back to it's normal place, so the AS beam is going toward AS55 and AS110, and a little bit is going to the camera. I have not yet aligned the beams actually on to the PDs.
REFL beam is dumped by a razor dump after the 2" lens. Manasa did some work (elog 7666) to the REFL path, and I'm not 100% sure how it was before, so I leave it to her to please work on during the day tomorrow. I think we need to put back the Y1 that used to be there, but I don't know where the optic is. I put a yaw dither on the PRM with awggui, and saw the REFL beam moving at my 2Hz dither frequency, so this time we actually have a useful beam coming out.
For a last few days I've been working on oaf and simulink model to simulate it. First I did online subtraction from MC when MC_L path was enabled. Inside my code I've added a sum of squares of filter coefficients so we can monitor convergence of the filter.
To to this I've measured path from OAF output to input without AA and AI filters. Then made a vectfit using 2 poles and zeros. Foton command
zpk( [-2.491928e+03;5.650511e-02], [-4.979872e+01;-3.278776e+00], 6.011323e+00)
My simulink model consists of 3 parts:
Adaptive filter in the model uses online c-code. It is connected to simulink block through an S-function. Sampling frequency of the model is 10 kHz. It works fairly fast - 1 sec of simulation time is computed in 1 sec.
I've tested FxLMS algorithm and MFxLMS algorithm that is faster. I plan to test 2 iir adaptive algorithms that are already coded.
In order to perform acoustic noise cancellation with MCL signal, I am trying to find sweet spots for microphones.
I set microphones at various places around MC chambers, and see how coherent microphones and MC signals are.
I had checked the half part of MC.
The acoustic noise around the MC2 chamber is most critical so far. I could subtract the signal and the sensitivity got 2 times better.
I will see the acoustic coupling from the other side of MC.
These fs are too short.
I propose to use lenses with focal lengths f1 = 22.2 mm and f2 = 25 mm. The beam diameter after the lenses will be dx = 164.05 um and dy = 163.19 um.
With reference to measurements made earlier: elog,
Beam parameters for Innolight 1W NPRO are:
wx0 = 160 um
wy0 = 181.1 um
z0x = -9.17 cm
z0y = -10.19 cm
The beam is clearly elliptical. We will introduce an additional pair of cylindrical lenses to circularize the beam before it enters the faraday.
I made calculations for the beam divergence ratio and checked with thor labs catalogue of cylindrical lenses to find pairs that will match the ratio.
I'm set on the mission to get the new bigger endtables setup for the auxiliary green laser; now that the tables are already here.
I want to have everything documented in this same thread for future reference. It has been a pain trying to filter relevant elogs. I'll be working on the layout redesign one at a time....starting with the ETMX end.
This is the simplest cartoon layout of ETMX endtable (not the actual table layout):
I have been searching through the elogs for the beam parameters measured earlier. I'm assuming they would not have changed much and will make calculations based on them.
However, we will have to change a few not-so-good mounts and include/exclude some optics.
P.S. HR (steer) are necessary steering mirrors and HR are just folding mirrors for the drawing.
[Rana, Ayaka, Jenne]
We aligned the REFL beam to the center of PD.
Also we removed the small black parts from mirror holder so that the beam is not clipped. They are originally for holding the mirror, but the mirror should be held by the small screw on the side of the mirror mount. This screw was hidden by the label, so we moved the label on the right hand side of the mirror mount (See a picture below).
Also we removed the half-wave plates and PBS so that laser power is increased.
Then I aligned the beam for PMC, locked MC, and centered the beam spots.
The MC2 pitch is a little bit high but still close enough to the center.
Jenne had also centered the beam spots on QPDs for WFS.
The ethernet power strips have been installed. 192.168.113.110 is on ETMX, 192.168.113.111 is on ETMY and 192.168.113.112 is on the vertex. I have also written an EPICS file "illuminator_control.adl" (currently stored in my named directory) that allows a user to turn individual sockets on and off at each of the three locations. Some short tests have indicated that everything is in working order.
Currently, no illuminators are hooked up to the power strips. However, the power control will most likely be ready for use tomorrow, granted I can find and use extension cords so that the illuminators might reach their respective power strips.
I'm sure Charles meant to also say that he connected the ETM power strips to the ethernet switches in those racks. For the vertex, the ethernet switch is in 1X2, but there isn't space in there, so the power switch was installed in 1Y2. The vertex ethernet cable is along the overhead inside cable tray.
I'm not sure what we want to do about connecting the new power strips to the illuminators. No illuminator is close enough that its built-in cable can reach the power strip, so we'll need extension cables or some such. Charles is going to ask Steve about the plan tomorrow.
In other, semi-unrelated news, the ITMXF camera has been not working for a while. The bottom right quad on the test mass tv has been dark for at least a week or two. Steve, when you have a chance (after the oplevs are all taken care of), can you see if there's something obvious that's wrong?
While helping Charles string the ethernet cable (elog 7698) for the power strip in the vertex (from 1Y1 to 1X1), I looked at the ITMX power cord. It was connected to the same power strip as the illuminator, which, since the illuminator was turned off by turning off the power strip, meant no power was going to the camera. Since Charles is very close to having the new power strips set up, I unplugged the ITMX illuminator and turned the power strip back on. ITMX camera is back to normal.
I turned on the power supplies for the output PZTs and pitch and yaw for PZT2. This is back to the condition that we had during atmosphere alignment, so after Ayaka has finished tweaking the MC, we can have a look at alignment of the interferometer.
Configured ethernet controlled power strips to have static IP addresses: 192.168.113.110, 192.168.113.111 and 192.168.113.112.
Wrote a python script to interact with the power strips that can turn individual sockets on or off via telnet.
This functionality will be implemented on the control room computer GUIs in short order.
The pressure is CC1 3e-4 Torr at 8 hours of pumping. Status: vacuum normal
The IFO is ready for light
I'm looking for IOO steering mirror power supplies. I found two so far: one at 1Y3 as Kepco + 75V and one at OMC_North rack -150V
Are there any more? The OMC is off.
ANSWER: only one of the steering PZT can be driven, so see their power supplies
The calendar tab now displays calendars with weeks that run from Sunday to Saturday (as opposed to Monday to Sunday). However, the frame on the left hand side of the main page still has 'incorrect' calendars.
After a brief look this morning, I called it and declared that we were ok to close up. The access connector is almost all buttoned up, and both ETM doors are on.
Basically nothing moved since last night, which is good. Jenne and I were a little bit worried about how the input pointing might have been effected by our moving of the green periscope in the MC chamber.
First thing this morning I went into the BS chamber to check out the alignment situation there. I put the targets on the PRM and BS cages. We were basically clear through the PRM aperture, and in retro-reflection.
The BS was not quite so clear. There is a little bit of clipping through the exit aperture on the X arm side. However, it didn't seem to me like it was enough to warrant retouching all the input alignment again, as that would have set us back another couple of days at least.
Both arm green beams are cleaning coming out, and are nicely overlapping with the IR beams at the BS (we even have a clean ~04 mode from the Y arm). The AS and REFL spots look good. IPANG and IPPOS are centered and haven't moved much since last night. We're ready to go.
The rest of the vertex doors will go on after lunch.
Jamie and Steve got the ETM doors on this morning.
We got the other heavy doors including the ITMs, BS and the access connector in place.
If nobody raises any concerns in reply to this elog, Steve will assume it as a green signal and will start pumping down first thing Monday morning after the final check on the access connector bellow screws.
Ayaka and I got the ITMY and BS door closed at 45foot pounds just now.
Oplevs and IP ANG are still centered. Why do the SRM and PRM move 5X more ? I could not check the sensing voltages because the computer failed.
AS and REFL are looking the same as last night.
ALL LOOKING GOOD!