This is nice - how about figuring out how to plot the measurement and model on the same plot? I guess we need to figure out how to go from counts to Watts.
I haven't done a units conversion for the measured vs. modelled plot, but at least we can compare the separation between the different degree of freedom signals. Figuring out why the REFL11 measurement and models are so different is still high on my to-do list. But at least the measurements that were taken last month are consistent with one another. EDIT: The separation angles match up pretty well between the 2 sets of measurements, but the overall rotation isn't really consistent. I do not believe that the phase rotation values that we're using online changed between the measurements, so the I&Q lines should be the same for both seets of measurements....however, I did not write down the phase rotation values at the time of the first measurement, so there's a chance that they were different. Also, something that I need to monitor is the coherence of my measurement, to make sure I'm really driving and measuring something.
2 measurements, with overall rotation arbitrarily rotated to make MICH lines match up:
Same 2 measurements, without the arbitrary overall rotation:
Measurement vs. Model, with the *modelled* phase arbitrarily rotated:
I am working on making the Proto-ASC less "proto". I have put IPC senders in the LSC model to send the cavity trigger signals over to the ASS model, for ASC use. I'm partially done working on the ASC end of things to implement triggering.
LSC should be compile-able right now, ASS is definitely not. But, I expect that no one should need to compile either before I get back in a few hours. If you do - call me and we'll figure out a plan.
I have finished my work on the LSC and ASS models for now. The triggering is all implemented, and should be ready to go. There are no screens yet.
I have *not* compiled either the LSC or the ASS, since Rana and Manasa still have the IFO.
With Rana's help/supervision/suggestions, I have closed the loop on the PRMI ASC servo with the new QPD. I think I've had it locked for ~30+ minutes now. It was locked for ~45 minutes, but then the MC momentarily lost lock. I immediately recovered the PRMI+ASC (after small PRM yaw tweaking, since the ASC isn't triggered yet, so the MC lockloss caused a big yaw step function to go to the PRM, which displayed a bit of hysteresis.).
My biggest problem was that I didn't really understand Koji's servo filter choices, so I wasn't using the right ones / doing good things. In particular, I need to compensate for the oplev servo filters. The oplev servo shape is something like ^, so the 1/(1+G) shape is something like =v= (ignoring the lower horizontal lines there). For tonight, we just turned off the PRM oplevs, but clearly this isn't a permanent solution. (Although, after Rana went in and roughly centered the PRM oplev, we noticed that turning the oplev on and off doesn't make a huge difference for the PRM....we should investigate why not. Also, we turned off the FM2 3.2Hz resonant gains in the PRM oplevs, since the Q of those filters is too high, much higher than our actual stacks).
Rana and I also locked the PRM-ITMY half cavity, and used that beam to realign the beam onto the POP QPD, POP110 PD, and the camera.
The POP QPD pitch and yaw signals with the half cavity have some noise, that looks like 60Hz crap. Since this goes away (rather, is much less noticeable) with the regular sideband-locked PRMI, we suspect this is a problem with perhaps the normalization, with the sum very low, and having some noise on it.
Once we had our ASC filters set up (not the 10Hz boost yet though, I think), if I increased the gain from -0.02 to -0.03, we start to get some gain peaking. With a gain of -0.04, the peak is very noticeable around 250Hz. We aren't sure where this is coming from, since it shouldn't be coming from the ASC loop. The UGF of that loop is much lower (I measured it, to check, and the UGF is ~5Hz). Anyhow, this is still a mystery, although the gain of -0.02 holds the cavity pretty well.
I measured the power spectra of the POP QPD pit, yaw, sum, as well as POPDC and POP110I, with the ASC loop on and off (dashed lines are with the loop on. You can see that the yaw motion as seen on the QPD was reduced by almost 2 orders of magnitude below 1Hz. It also looks like we can win some more by turning on the equivalent pitch ASC servo (this is also something we see when looking at the dataviewer traces).
I also tried to measure the PRMI sensing matrix, but I get some weird results, even after I double the drive actuation. I need to be checking whether or not my drive is actually coherent with the error signals that I'm seeing, because right now I'm not sure that I believe things. I'm going to leave that on the to-do list for tomorrow night though.
* Engage POP QPD -> pitch loop, copying yaw loop.
* enable ASC triggering
* model PRMI sensing matrix and error signals, bringing one arm into resonance
* Lock the PRMI, and bring the Xarm into IR resonance using the ALS system.
Here are some numbers and plots from the night:
Right now, I'm locking the LSC with:
MICH LSC with AS55Q, FMs 4 and 5 on, FM 3 is triggered, gain = -40.0, normalized by sqrt(POP110I)*0.1
PRCL LSC with REFL33I, FMs 4 and 5 on, FM 9 is triggered, gain = +2.5, normalized by sqrt(POP110I)*10
(FM3 of MICH and FM9 of PRCL are the same, just in different spots).
The ASC (only POP yaw -> PRM yaw right now) has:
FMs 1,2,5,6 on (1 = integrator [0:0.1], 2 = 3.2 res gain, 5 = [1000,1000:1 and gain of 0.01], 6 = 10Hz boost). Gain = -0.020, Limit=5000.
Turn off the input, turn on the output and the gain, clear the histories (to clear out the integrator in FM1), then turn on the input.
PRM oplev is OFF. (need to put in a filter to compensate for it in the ASC servo, but for tonight, we just turned it off.)
We measured the spectra of the POP QPD signals with the ASC loop on and off:
I also measured the ASC loop (with the PRM oplev still off):
(sorry about the separate plots - I can't make DTT give me more than 2 plots on a page at a time right now, so I'm giving up, and just making 3 separate pages)
Weird sensing matrix, unsure if I'm really getting good coherence:
Not sure why it was so poorly aligned, since the misalignment "event" happened while we were all away at lunch, but I steered the MC optics until their SUSYAW and SUSPIT values were about the same as they were before they got misaligned. MC autolocker took over, and things are back to normal.
The BLRMS are totally crazy today! I'm not sure what the story is, since it's been this way all day (so it's not an earthquake, because things eventually settle down after EQs). It doesn't seem like anything is up with the seismometer, since the regular raw seismic time series and spectrum don't look particularly different from normal. I'm not sure what's going on, but it's only in the mid-frequency BLRMS (30mHz to 1Hz).
Here are some 2 day plots:
All of us in the control room / desk area heard a sudden whoosh of air a few minutes ago. It kind of sounded like a pressure washer or something. We determined that the northmost nitrogen bottle outside the front door was letting out all its gas.
It's a gazillion degrees outside (okay, only 91F, according to a google of "Caltech Weather"), and those bottles are in direct sun all day.
We are leaving the bottle as-is, since it seems like its has finished, and nothing else is happening.
Last night before dinner, I copied over the ASC yaw servo filters to the ASC pitch filter bank. Using ASC gain of +0.001, I was getting the ~250Hz oscillations that Rana and I had seen with yaw.
Rana pointed out to me that my measured TF of the yaw loop doesn't look right up in the several hundred Hz region:
As you can see on the right side, which is all of the PRCL ASC yaw filter banks, multiplied by a simulated pendulum filter, the magnitude should just keep decreasing. However, on the measured plot on the left, you can see that I have a little gain hump. I'm not sure what this is from yet.
Rana had the epiphany that I didn't have any antiwhitening for my POP QPD. Ooops.
We looked at the schematic for the Pentek Generic board (pdf), and saw that it has a Zero @ 15Hz, and Poles @ 150Hz and 1500Hz, times 2 stages. We determined from the TF that I posted that probably both stages are engaged, so I made an antiwhitening filter consisting of the inverse (so, 2 poles at 15Hz, 2 zeros at 150Hz and 2 zeros at 1500Hz). [Rana points out that for this low frequency system we may not want to include the 1500Hz compensation, since it is probably just enhancing ADC noise]. The ASC system worked really well, really easily, after that.
Another note though, the AA stage of the Pentek Generic boards have 4 poles at 800Hz, which are not compensated.
Rana also added a 60Hz comb to the filter bank with the AntiWhitening, since the QPD has an unfortunately large amount of 60Hz noise. Also, the 60Hz lowpass in the ASC loop was engaged for both pitch and yaw.
Rana, Lisa and Manasa also found that the ASC system was *more* stable with the PRM oplev ON.
So, the ASC locking situation is:
PRM oplev loops on.
AS-POP_QPD_[PIT/YAW] filter banks with FM1, FM6 on.
ASC-PRCL_[PIT/YAW] filter banks with FM1, FM5, FM6 and FM9 on.
ASC-PRCL_YAW_GAIN = -0.040
ASC-PRCL_PIT_GAIN = +0.030
(No triggering yet).
The ASC Up and Down scripts (which are called from the buttons on the ASC screen) have all of these gain settings, although they assume for now that all the filters are already on.
Here's a screenshot of the power spectra showing the angular motion suppression. The PDF is attached so you can zoom in and see some details. The dashed lines are the "PRMI locked, ASC off" case, and the solid lines are the "PRMI locked, ASC on" case. You can see that according to the QPD, we do an excellent job suppressing both the pitch and yaw motion (although better for yaw), but there isn't a huge effect on POPDC or POP110I. While we could probably do better if we had a 2 QPD system with the QPDs at differet gouy phases, this seems to be good enough that we can keep the PRMI locked ~indefinitely.
I would like to compile the ASC model, so that I can implement triggering. For tonight, we did not have the ASC engaged during our PRMI+Xarm tests (see Manasa's elog), but I think it'll make things a little easier if we can get the ASC going automatically.
[Lisa, Rana, Jenne]
Lisa asked to see a model of the PRMI sensing matrix with REFL165 included, in the hopes that it wouldn't be as degenerate as REFL33.
The conclusion, immediately after looking at this, is that I should make sure the REFL beam is nicely aligned onto the REFL165 PD (Koji did some tests, swapping out the REFL165 resonant PD with a broadband PD, and I don't remember if he aligned beam back onto the REFL165 PD). Then, I need to measure the PRMI sensing matrix, including REFL165. Hopefully, it is similar to the model, and we can use it as our 3f diode for locking.
I have modeled the PRMI sensing matrix as I bring the Xarm into resonance. In optickle, I have the PRMI on sideband resonance, the ETMY is artificially set to have a transmission of 1, and the ETMX has it's nominal transmission of 15ppm. I start with the ETMX's microscopic position set to lambda/4 (antiresonant for IR in the arm), and take several steps until the ETMX's microscopic position is 0 (resonant for IR in the arm).
Modeled sensing matrix, units = W/m, Offset = 2.66e-07, phase in degrees
MICH Mag MICH Phase PRCL Mag PRCL Phase
AS55 3.348E+04 142.248 5.111E+03 70.571
POX11 3.968E+01 -66.492 1.215E+04 54.312
REFL11 3.231E+05 24.309 9.829E+07 144.311
REFL165 9.946E+03 -159.540 4.540E+05 -64.710
REFL33 1.963E+04 -168.530 1.573E+06 -2.744
REFL55 1.160E+06 -6.755 5.429E+07 86.895
Modeled sensing matrix, units = W/m, Offset = 0, phase in degrees
MICH Mag MICH Phase PRCL Mag PRCL Phase
AS55 1.647E+06 57.353 3.676E+06 -81.916
POX11 3.927E+02 -118.791 2.578E+04 -102.158
REFL11 7.035E+05 61.203 1.039E+08 167.149
REFL165 1.602E+04 -144.586 5.971E+05 -49.802
REFL33 2.157E+04 171.658 1.940E+06 -9.133
REFL55 1.822E+06 7.762 6.900E+07 101.906
For REFL55, the MICH magnitude increases by a factor of 1.6, while the PRCL magnitude increases by 1.3 . The MICH phase changes by 15 degrees, while the PRCL phase also changes by 15 degrees. Just eye-balling (rather than calculating), the other REFL PDs look to have similar-ish magnitude and phase changes. Certainly none of them are different by orders of magnitude.
Here is the Sensing Matrix movie (sorry for the iffy quality - my movies usually come out better than this):
This is the sensing matrix for the sideband locked on PRMI, bringing the Xarm into resonance from anti-resonance, in 20 equally-spaced steps. You can see the microscopic ETMX offset (units of meters) in the title of the figures.
I was surprised to see some of the 'jumps' in the sensing matrix that happen near the end, when the arm is almost in resonance. I'm in the process of making movies of the error signals as the Xarm is brought into resonance. I'll have to post those in the morning, since they're taking a long time to produce and save, however when I looked at a few, there is some weird stuff going on as we get close to resonance, even with the 3f signals.
The modeling phone call is in the morning, but if anyone who is not regularly on the call has thoughts, I'm all ears.
I am prepping to do the POP QPD calibration, and so have turned off the POP QPD, and put it onto a micrometer stage. My plan is to (after fixing the ASC servo filters to make the servo AC coupled, rather than DC coupled) lock the PRM-ITMY half cavity, and use that beam to calibrate the QPD. While this isn't as great as the full PRMI, the PRMI beam moves too much to be useful, unless the ASC servo is engaged.
While on the table, I noticed 2 things:
* In order to place the micrometer, I had to temporarily move the POP55 RFPD (which has not been used in quite a long time). I think it's just that the panel-mount SMA connector isn't tight to the panel inside, but the RF out SMA cable connector is very loose. I have moved the POP55 RFPD to the very very south end of the SP table, until someone has time to have a quick look. (I don't want to get too distracted from my current mission, since we haven't put beam onto that PD for at least a year).
* The ITMX oplev beam setup isn't so great. The last steering mirror before the beam is launched into the vacuum is close to clipping (in yaw... pitch is totally fine), and the steering mirror outside of vacuum to put the beam on the QPD is totally clipping. The beam is falling off the bottom of this last steering mirror. Assuming the beam height is okay on all of the input optics and the in-vac table, we need to lower the last steering mirror before the oplev QPD. My current hypothesis is that by switching which in-vac steering mirror we are using (see Gautam's elog 8758) the new setup has the beam pointing downward a bit. If the problem is one of the in-vac mirrors, we can't do anything about it until the vent, so for now we can just lower the out of vac mirror. We should put it back to normal height and fix the oplev setup when we're at atmosphere.
I was bad, and forgot to elog the most important part of my work yesterday - that I had rotated the POP QPD by 90 degrees, so that I could fit the micrometer onto the table. There is a sticker on the front of the QPD to indicate which direction is "X" and "Y" for the output of the readout box. Right now (and the way that I will mount the QPD to the table, after I redo the calibration today), X is PITCH, and Y is YAW. Koji and Nic swapped the cables to the ADC to make this all consistent.
Yesterday, I locked the PRM-ITMY half cavity, and tried to take calibration data. However, with no ASC servo engaged, the beam was still moving. Also, with only the half-cavity, I had very little light on the QPD, and since it has internal normalization, the outputs can get a little funny if there isn't enough light. I had checked, and even with the gain cranked up to maximum, the "light level too low" LED was illuminated. So, my calibration data from yesterday isn't really useful.
Today, hopefully after lunch, I will lock the PRMI with the new AC-coupled ASC servo, so that I can have the servo on, and the PRMI locked on the sideband, so that I have more light on the QPD.
After that, it seems that the final thing we need to do before we vent is hold an arm near, but off resonance, lock the PRMI, and then swing the arm in and out of resonance a bit.
Calibration data for the POP QPD has been taken, with the PRMI locked on sideband (with AS55Q and REFL33I, since it stayed locked longer with those 2). ASC was on, AC coupled.
We didn't get too far on either side of center of the QPD, since the ASC servo would go unstable, so we only explored the roughly linear region. Data / plots / analysis to follow.
[Annalisa, Jenne, Nic]
After having troubles with the Xarm earlier (maybe Manasa can write/say something about this? Something about perhaps seeing the phase tracker jump, and cause it to lose lock?), we moved on to the Y arm.
Annalisa locked the Yarm green, and closed the ALS loop. I believe that earlier today, she tuned the gain such that we don't start getting gain peaking at a few hundred Hz. We would like to get a script going, so that it's not so labor intensive to reclose the ALS loop after an MC lockloss....but that's a daytime task.
We then found the IR resonance, using only the Yarm ALS system. After Manasa's work yesterday, the Yarm was very stable while locked with the ALS. We took a power spectrum of POY11_I_ERR, which I have calibrated using the number in elog 6834 of 1.4e12 cts/m, or 7.14e-13 m/ct. See the figure below.
After that, we changed the offsetter2 offset such that the arm was off resonance, but not so far off that we crossed any significant resonances (in particular, we wanted to not go as far as the 55MHz resonance).
Then, I tried to lock the PRMI for a while, but the alignment wasn't very good. We knew that the Yarm was well aligned, since our IR resonance was > 0.98, but it had been a while since we had aligned the X arm. I tweaked the ITMX position to make the Michelson dark, and then tried acquiring PRMI lock. At first, I tried with REFL165 I and Q, but with the non-ideal alignment and the offset in the 165 diode (LSC offsets was not run this evening), I wasn't catching any locks. I then switched to AS55Q and REFL33I, but wasn't able to catch lock there either.
The MC lost lock, which made us lose the ALS loop, but the ALS had been locked for more than 30 minutes, at least. I tried locking the PRMI with the current alignment (after having misaligned ETMY), but was only able to get lock stretches of 1 second at maximum.
We are calling it a great success for the night, since we have confirmed that, at least for the Yarm, Manasa's beatbox work has improved things. Also, we have a pretty solid plan for trying the PRMI+arm tomorrow, even though it didn't work out tonight.
These are the data, one plot for when the vertical QPD position was changed, and one for when the horizontal (yaw) QPD position was changed.
The micrometer is in inches, so 1 unit is 0.1 inches, I believe.
Clearly, I need to redo the measurement and take more data in the linear region.
I tried to retake POP QPD calibration data again today. The MC was mostly fine, but whenever the PRMI unlocked, both ITM watchdogs would trip. I'm not sure what was causing this, but the ITM alignment wasn't perfect after this kind of event, so I felt like I was continuously locking and realigning the arms to get the alignment back. Then, after turning on the ASC and tweaking up the PRM alignment for maximum POP110I signal, I had to recenter the QPD, so none of my previously taken data was useful. Frustrating. Also, I had recentered the PRMI-relevant oplevs, but I had these weird locklosses even with nicely centered oplevs.
I have given up for the daytime, and will come back to it if there's a spot in the evening when arm measurements aren't going on.
Here is the data from last week, and the data from today. The micrometer readings have been calibrated into mm, and I have fit a line to the linear-looking region. Obviously, for the Pitch calibration, I definitely need to take more data.
Those 'peaks' for the oscillations seem ridiculously broad. I think you should look again, really quickly, with smaller bandwidth at, say, the 2kHz oscillation, to make sure it looks reasonable.
I took POP QPD calibration data with a new method, on Rana's suggestion. I locked the PRMI, and engaged the ASC servo, and then used awggui (x8) to put dither lines on all of the PRMI-relevant optic's ASCPIT and ASCYAW excitation points. I then took the transfer function of the suspensions' oplev signals (which are already calibrated into microradians) to the POP_QPD signals (which are in counts). This way, we know what shaking of any optic does to the axis translation as seen by the POP QPD. We can also infer (from BS or PRM motion for PR3, and ITMX motion for PR2) what the folding mirrors do to the axis translation. Note that we'll have to do a bit of matrix math to go from, say, PRM tilt effect to PR3 tilt effect on the axis motion.
The data is saved in /users/jenne/PRCL/July152013_POP_TFs.xml . There is also a .txt file with the same name, in the same folder, listing the frequencies used by the awg.
I'll analyze and meditate tomorrow, when my brain is not so sleepy.
The proto-ASC now includes triggering. I have updated the hacky temp ASC screen to show the DoF triggering. I have to go, but when I get back, I'll also expose the filter module triggering. So, for now we may still need the up/down scripts, but at least the ASC will turn itself off if there is a lockloss.
Last night, I took sensing matrix data at various different offsets for the Yarm. The sensing matrices I measured were of the PRMI, while the Yarm was (a) Held off resonance, (b) Held at ~50% peak power, and (c) Held on resonance.
The dither lines were clear in the MICH and PRCL spectrum, so I think I'm driving hard enough, but something else seems funny, since clearly the REFL165 I and Q signals were not completely overlapping last night. If they were, we wouldn't have been able to lock the PRMI using REFL 165 I&Q.
Anyhow, here's the data that was taken. Data folder is ...../scipts/LSC/SensingMatrix/SensMatData/
Yarm off resonance, SensMat_PRMI_1000cts_580Hz_2013-07-18_012848.dat
Yarm at ~50% resonance, SensMat_PRMI_1000cts_580Hz_2013-07-18_013937.dat
Yarm on resonance, SensMat_PRMI_1000cts_580Hz_2013-07-18_013619.dat
The results of today's MC spot position measurements:
spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[2.3244717046516197, -0.094366247149508087, 1.6060842142158149, -0.74616561350974353, -0.67461746482832874, -1.3301448018100492]
MC1 and MC3 both have spots that are a little high in pitch, but everything else looks okay.
I have just centered IPPOS, as well as PSL POS and PSL ANG (also called IOO POS and IOO ANG on the screens). Annalisa is working on placing mirrors to get the IPANG beam to its QPD, so that one will be centered later.
I have some data for how much motion of any PRMI-relevant optic affects the beam seen by the POP QPD.
For this, I am using the QPD calibration from the micrometer (elog 8851) to get me from counts to mm of motion. Note that the pitch calibration hasn't been redone (I tried locking the PRMI this afternoon, but ITMX kept drifting away from me**, so I didn't get any more data.) The pitch calibration is obviously very rough, since I only have 2 points defining my fit line.
Anyhow, if we assume that's close enough to get us started, I now have a calibrated QPD spectrum:
As detailed in elog 8854, I took single frequency transfer functions, to determine the effect at the QPD from shaking any single PRMI optic. These transfer functions gave me a conversion factor between the optics' oplev readings (in microradians) to the counts seen at the QPD. I used this number, as well as the QPD calibration from the micrometer data, to convert each optics' oplev spectra to motion that one would expect to see at the QPD.
I have not yet completely figured out how to make an estimate of the PR folding optics' affect on the POP QPD spot position, if I know their motion. The current plan is to do as Den did in elog 8451, and infer the PR2/3 motion from the ITMX/BS motion measured by the oplevs. My plan was to take the spectra of the oplev signals while the BS/ITMX are undamped, divide by the SOS pendulum transfer functions, then multiply by the TT transfer functions (which I finally wrote down in elog 8564). I'm planning on using the undamped data, since the oplev signals are still within the linear range of the oplev QPDs, and I won't have to take the SUS damping into account. Anyhow, after I do that, I'll have an idea of how much the tip tilts are moving, but not what that does to the cavity axis.
However, after looking at the plots below, it seems like the PRM is the main culprit causing the PRC axis motion, although the BS (and to a smaller extent the ITMs) are not innocent. Since the plots get very busy very quickly, I have many plots, each plot comparing one of the above QPD spectra (either pitch or yaw) with a single optics' oplev inferred motion.
EDIT: After talking with Koji, I realize that, since the ASC was engaged during the PRM oplev spectrum measurement, I cannot yet say whether the motion is due to PRM, or if it is from PR2 or PR3, and imprinted on the PRM via the ASC servo. The lump where the PRM-caused motion is greater than the QPD spectra is entirely in the region where the ASC is active. So, the QPD motion I expect without the ASC would be something like the green trace in the PRM comparison plots. The blue trace is then the closed loop measurement. Since the ITMs and BS are below the closed loop values, they aren't the ones causing the big lump. I should retake all of these spectra at a time when the PRMI is locked, but the ASC is not engaged. I'm not sure if I'll have a chance to do that tonight or not. If I can find some GPS times when the PRMI was locked, before we had ASC, I can get the oplev data.
I think part of the reason PRM is dominating is that it's damped motion is ~10x greater than any other optics', most noticeably the BS'. I'll write a quick separate elog about this. Also, note that the ~3Hz resonant gain had been turned off in the PRM oplev loop, but not in any other loops. This is why there isn't the sharp dip in the PRM's oplev motion. Also, since the PRM ASC was engaged for this measurement, and the ASC pushes on the PRM to minimize the QPD motion, it isn't totally crazy that the PRM's motion is greater than what we actually see at the QPD, if it is compensating for the motion of other optics.
** Re: PRMI locking this afternoon, it was almost as if ITMX were bi-stable. I aligned both arms, to set the ITM positions. Then, I would lock and tweak up the michelson to get the AS port nice and dark (usually touching ITMX today, since it seemed like the drifter....ITMX at this point was usually between -7 and -15 microradians in pitch from the center of the oplev QPD). When I then brought the PRM back into alignment, ITMX was starting to drift away. As soon as I hit the LSC Enable switch, and looked back over to the OpLev screen, ITMX was misaligned, usually around -65 urad in pitch. I did this circus probably 3 or so times before giving up. Koji said that he had seen this bi-stability before, but he didn't remember what fixed it. The drifting that Koji mentioned in elog 8801 seems to have been fixed by centering all the PRMI oplevs every day, but I had already done that, and was still seeing ITMX drift.
After Koji and I lowered the power into the PMC and saw that the MC locked nicely, I remeasured the spot positions (no alignment on the PSL table, or of the MC mirrors has been done. Also, WFS are off, since there isn't any power going to them).
spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[1.1999406656184595, 0.63492727550953243, 1.0769104750021909, -1.0260011922577466, -1.059439987970527, -1.2717741991488549]
The spot positions seem to have actually gotten a bit better in pitch (although between 2 consecutive measurements there was ~0.5mm discrepancy), and no real change in yaw. This means that Rana was right all along (surprise!), and that decreasing the power before the PMC reduces alignment pain significantly.
After everyone's work today (good teamwork everybody!!), we are a GO for the vent.
Steve, please check the jam nuts, and begin the vent when you get in. Thanks.
We will open the BS and ITMY doors first thing tomorrow morning. I plan to try to be in around 9 am. The first order of business will be to flip the folding mirrors that are not currently flipped (SR2, SR3, PR3).
SR2 is flipped, and reinstalled. We did that before lunch, and we're about to go in and work on SR3 and PR3.
EDITS / Notes:
I set dog clamps to have a reference position of where the tip tilt was, then I removed SR3 from the chamber. Once out, I followed the same procedure I used for PR2 during the last vent - I removed the whole suspension (top mount, wires, optic) from the cage, and laid it down flat. Then I loosened the set screw which pushes on the teflon nudge, removed the mirror, inspected it, and put it back in, with the HR side facing the back side of the ring. Then I replaced the suspension system in the cage, and put the mirror back into the chamber.
When I loosened the teflon nudge at the top of the mirror holder ring, the optic seemed to fall down a tiny bit. I think this implies that the HR surface of the optic did not used to be parallel to the front face of the mirror holder ring. When I put the suspension back onto the cage, the pitch balancing was very bad. We checked the level of the table that I had the cage on, and it was miraculously pretty level, so I did the pitch balancing out of the chamber.
Also, during my quick inspection of the mirror (not thorough, just using room lights), I noticed a small fleck of lint near the edge of the optic on the HR surface. The HR surface is now on the outside of the SRC, but we should still blow at the optic with the ionized nitrogen to get it off.
I did not think to check the fine-tuning alignment of SR2....Koji did that after lunch (which I will elog about in a separate elog).
Yesterday afternoon, I went back into the BS chamber, and flipped both PR3 and SR3. Now all of the recycling cavity folding mirrors have been flipped.
For PR3, I followed the same procedure as SR2, setting a reference position, removing the optic, flipping it, etc. When I put it back in, I realized that since this has a 41 degree angle of incidence, the beam going to the BS had translated north by ~1cm. After some fiddling, Koji pointed out that the 2 degree wedge probably had a more significant effect than just the HR surface having moved back a small amount. Anyhow, we adjusted PR3 such that we were going through the BS aperture, as well as the ITMY aperture.
During the flip of PR3, Annalisa and I noticed that the arrow on the barrel of the LaserOptik mirrors also indicates the thickest part of the wedge. This is opposite of our SOS optics, where the arrow's position on the barrel indicates the thinnest part of the wedge. For both PR3 and SR3, I kept the arrow on the same side of the optic as it was originally.
I then flipped SR3, following again the same procedure. PR3 I had done a tiny bit of pitch rebalancing, although I think it was unneccessary, since it is within what we can do with the poking/hysterisis method. SR3 I did not do any pitch rebalancing. With PR3 aligned at least to the ITM, Koji and I aligned SR3 and SR2 so that the AS beam was hitting the center of all the SRC optics. We also adjusted the steering mirrors after the SRM to get the beam centered on PZT3, the last optic on the BS table, which launches the beam over to the OMC chamber. We scanned around a bit by turning the PZT's knobs, but we were unable to see the AS beam on the camera.
[Jenne, Manasa, Koji]
Earlier today, we locked and aligned both the X and Y arms.
I then went into the BS chamber, put on the BS' aperture, and put an aperture along the AS path. (We had Michelson fringes, so I centered the aperture around the fringes. I used one of the brass ruler things that we use to center the beam on ITMs and ETMs, on a riser. I put this aperture at the edge of the BS table, after the AS beam is launched toward the OMC chamber. The idea was to replace PR3 such that I could get the beam back through the BS aperture, and the brass ruler aperture, in hopes that we would see arm flashes, and not have to open the ITMY and ETMY heavy doors.)
I set references on the table so that I could put PR3 back in its original position, then removed PR3 from the chamber.
Steve set up a HeNe for me, that we pointed through the optic. The ghost beam was very high, indicating (as expected) that the wedge was not perfectly horizontal.
I took the suspension off of the cage and laid it down, as I have in the past.
I removed the optic from the suspension, to try to figure out which was the fat vs. skinny side. I noticed that there are very faint marks on the actual fat and skinny sides of the optic. (Mpral - for the LaserOptik mirrors, look for the faint lines that are the full width of the barrel, not the placement of the arrow which marks the HR side). I put the optic back in (HR side toward the back, fat side on the left (as you look at the face of the optic), which is consistent with the picture in the Optical Layout page of the Wiki, near the bottom.) the optic holder ring.
I put the suspension back on the cage, and saw that the HeNe's ghost beam was now nearly horizontal relative to the straight-through beam. Excellent. Also, the pitch balancing didn't seem to change noticably, which I determined was within "poking" distance of where we need it to be.
I put PR3 back onto the BS table, and adjusted it around until I got the beam through both the BS aperture, and the one on the AS path. As usual, this took quite a while, but as soon as I got through both of those apertures (really at the same place, not close to being through them, but as close as I could tell by eye - this is what took forever), Koji and Manasa saw flashes in the Yarm! Yay!
Since I had to move PR3 in angle a tiny bit, I reset the references, then dogged down PR3. We still had flashes, this time in both arms, so we closed up the light doors.
We have now locked and aligned both arms in IR after the adjustment of PR3, and see both arms' green at 01 or 02. We are about to start checking the green positioning on the periscopes. We will also need to check the AS path, as well as IPPOS and IPANG before we close up. We see REFL on the camera.
Separately - Manasa remembered that 2 clean things were dropped yesterday - a screw, and an allen key. Since they're both Clean, we're not too worried, although she thinks a long-armed person may be able to reach the allen key.
[Manasa, Koji, Jenne]
We went into the BS and IOO chambers, and aligned the green beams such that they came out of the vacuum chamber. The idea here was to get the beams at the same height, but slightly offset in yaw. This required moving the Periscope on BS table, PBS in front of that periscope, the Periscope on the IOO table, and 2 steering mirrors on the IOO table after the 2nd periscope. The tables were not releveled, although we have aligned the full interferometer to this situation, so we do not want to touch the tables. The MC spot positions are still consistent with those measured earlier this afternoon, before this work, so I'm not concerned.
We confirmed that both green beams are hitting a good place (centered in pitch, and just left and right of center in yaw) on the mirror in the OMC chamber, and are getting to the center of the first mirror on the PSL table. We then coarsely aligned the beams on the PSL table.
We then relocked and aligned the arms for IR, and checked that the AS beam is centered on the mirrors in the BS chamber, and that the beam is coming out, and to the AS table. I touched the last mirror before PZT3 a small amount in yaw, and then PZT3 in pitch and yaw, until we saw the beam recentered on the first mirror on the AS table. At that point, we were also back to the center of the AS camera (which is good, since Koji had aligned all of that the other day). So, the AS beam is good.
We checked IPPOS, and have centered the beam on all the mirrors, and aligned the beam onto the QPD.
We checked IPANG, by looking through the viewports at the mirrors in the ETMY chamber. We are now centered in yaw, but clipping a bit low. This is what we want, since we always end up drifting high during the pump-down.
We see a nice, unclipped REFL beam on the camera.
We see a beam a little high on the POP camera, but Koji looked on the table with a card, and saw the beam....we just need to do minor alignment on the out of vac mirrors.
We checked again that the green TEM00 beams from both arms come to the PSL table.
We are getting POX and POY out, since we are using them to lock and align the arms.
Manasa and Koji recovered one clean allen key from the bottom of the chambers, but one remains, as a sacrifice to the vacuum gods.
I believe that, with the exception of checking the oplevs and taking photos of PR3, and the green steering optics, we have finished all of our vent tasks. We should do a quickie alignment on Monday, check the oplevs, take some photos, and put on the heavy doors. Pumping can start either Monday afternoon or Tuesday morning.
[Koji, Manasa, Jenne]
The Y arm was locked in IR, and we saw flashing in the Xarm (Gautam had the Xarm for green work when we began). I checked IPANG, and the beam was beautifully unclipped, almost perfectly centered on the first out of vacuum mirror. I aligned the beam onto the QPD.
We then swapped out the MC Y1 that we use at low power, and replace the usual 10% BS, so that we wouldn't crispy-fry MC REFL. Manasa adjusted the half wave plate after the laser, to maximize the power going toward the PMC. We relocked the PMC, and see transmission of ~0.84, which is at the high side of what we usually get. The beam was aligned onto MC REFL and centered on the WFS, and the MC was locked at nominal power. Koji tweaked up the alignment of the MC, and ran the WFS offset script. I aligned beam onto POP QPD and POP110 coarsely (using a flashing PRC, not a locked PRM-ITMY cavity, so the alignment should be rechecked). The arms have both been locked and aligned in IR....the green beams need to be steered to match the current cavity axis.
The AS beam, as well as REFL and POP, are all coming out of the vacuum nicely unclipped.
Notes: When Koji was aligning the SRM to get the SRC cavity roughly aligned (the AS flashes all overlapping), we noticed that there is some major pitch-yaw coupling. Serious enough that we should be concerned that perhaps some connector is loose, or an actuator isn't working properly. This should be checked.
Moral of the story: Coarse alignment of all mirrors is complete after pump-down and we have IR locked and aligned to both arms at nominal power.
Still to do:
* Restore PRM, align beam onto the REFL PDs.
* Lock PRM-ITMY cavity, align beam onto POP PDs.
* Align AS beam onto AS55.
* Recenter all oplevs.
* Recenter IPPOS and IPPANG at nominal power.
* Start locking!!
I have furthered Koji's work, and moved the filter on/off state for all the filter banks also to the burt snapshot.
Turning on the ASS is now much faster than it was originally, with the ezcawrites in series.
We have looked a little more at the SRM situation. We aligned the SRM, and then aligned the oplev, so that we had a convenient monitor of the optic's motion.
When we use the _COMM channels, which are the usual ones on the IFO_ALIGN screen, the pitch slider makes pitch motion, but the yaw slider makes the oplev spot move ~45degrees from horizontal.
However, when we use the bias channels that are in the front end model, parallel to the ASC path, pitch moves pitch, and yaw moves pure yaw.
So, we conclude that the SRM coils are fine, and there is something funny going on with the slow part of the actuation.
Koji restarted the slow computer susaux, and burt restored it, but that did not fix the situation. We went inside and looked at all of the ribbon cable connections, and pushed them all in, but that also has not fixed things.
We have been looking at D010001-b, the coil driver board, and we think that's where the summing resistor network between the slow bias slider, and the coil outputs from the fast model exists. (It's not 100% clear, but we're confident that that's what is going on).
Tomorrow, we will pull the SRM's coil driver board, and see if any of the components in the slow slider path, before the summing point, look burned / broken / bad.
Getting rid of the LO transmission will certainly help / be good. After adding these channels, the RFM model is regularly hitting 62usec (out of a max acceptable of 60).
I'm not really sure why the ASS was involved in this. I feel like it might have been simpler to just do everything in the ASX model, to keep things cleaner. Also, the IPC blocks for this stuff (in both ASS and ASX) are not on the top level of the model. I had thought that this was expressly forbidden (although I'm not sure why). I'm emailing Jamie, to see if he remembers what, if anything, is breakable if the IPC blocks are down a level.
- We are ready to implement ASS for PRM
I have added an IPC sender from the LSC model, to send POPDC to ASS. I have copied over the structure of the arms' ASS, to do the same for PRCL. I have set it up to dither the PRM, and feed back to the PRM. I did not include an LSC set, since I'm assuming that we'll set the input pointing with the arms, and just want to move the PRM to maximize POPDC.
Models have been compiled, installed, and restarted, and the daqd was restarted.
I have added the PRCL ASS to the main ASS screen, and created the servo and lockin screens. The filters loaded are the same as those used for the arms (bandpasses and lowpasses for the lockins, and an integrator for the servo).
I'm going to try to lock, and get the ASS to work.
I guess I was thinking that POPDC was a proxy for any type of PRCL lock. Even if we're sideband locked, there is still some signal in POPDC (although it is very small relative to a carrier lock - ~40cts vs. 1,000cts). However, as soon as this question was asked of me, I realized that one of the 2f demodulated signals made more sense.
Since I want the ability to choose between POP110 and POP22, I have put a little 1x3 input matrix before the PRCL lockins in the ASS model. Since POPDC was already there, I included it as an option in the matrix (in case we ever want to do some PRCL ASS after we have some carrier resonating as well).
When I came in this morning, I noticed that the Mode Cleaner had not been locked for at least the past 8 hours. We moved the MC SUS sliders until the MC SUSPIT and SUSYAW values for each mirror were back to approximately the place they were the last time the MC was nicely locked (~12 hours ago). This got the MC flashing TEM00, so we thought we were doing well.
However, if the servo was enabled, any time the cavity flashed a small-order mode (especially 00), the mirrors would get super kicked. Not good.
We went to investigate, and discovered that the RFPD aux laser was left on again. We turned that off, however that didn't fix the situation.
Manasa suggested checking that the WFS were really, really off. When we looked at the WFS master screen, we noticed that although the WFS servos were off, the MC mirrors' ASC filter banks had non-zero inputs. We checked, and this is not from the MCASS, nor is it from the MC WFS lockins. At this point, I have no idea where these signals are coming from. I have turned off the ASC outputs for all the MC mirrors (which means that we cannot turn on the WFS), and the MC locks fine.
So, we need to know where the ASC signals are coming from. There isn't anything that I can see, from any screen that I can find, that indicates some signals being sent over there. Has anyone done anything lately? I know Koji was working on IPC stuff the other day, but the MC was locking fine over the weekend until yesterday afternoon, so I suspect that's not the culprit.
I have turned off the outputs of the WFS lockins, as part of my turning things off, so if whatever script needs them doesn't enable them, they should be turned back on by hand.
Here are a bunch of sensing signals. The configuration is always DRMI. Except for the optic noted in the title and the x-axis of any individual plot, other optics are held in their nominal position. DRMI condition is sidebands resonant in PRCL, 55MHz sideband resonant in SRCL. Each plot has an error signal, as well as the 2f signals at POP and AS.
The phases of POP22 and POP110 have been adjusted so that the I signal is maximized when everything is at the nominal positions (sideband resonant for PRMI). The phase of AS110 has been adjusted so that the I signal is maximized when the DRMI is in the nominal position (f2 resonant in SRC). The phases of the 1f1, 1f2, 2f1 and 2f2 REFL signals were all adjusted to have max PRCL signal in the I phase. AS55 was adjusted to have max SRCL signal in the Q phase.
According to the wiki, REFL 11 has a transimpedance of 4.08kV/A, and REFL 55 has a transimpedance of 615V/A. This is a ratio of ~6.5 . My optickle simulations from earlier this evening indicate that, at maximum, there is a ~factor of 2 more signal in REFL 11 than REFL 55. This is a factor of order 10-15. Then, REFL 55 has 15dB whitening gain, which is a factor of ~4. So, this explains why we're seeing so much more digital signal on REFL11 than REFL55.
Tomorrow, I need to replace the 50/50 beam splitter that splits the beam between REFL55 and REFL11 (33 and 165 have already had their light picked off at this point). I want to put in a 10% reflector, 90% transmission beamsplitter. Steve, can you please find me one of these, and if we don't have one, order one? This will give us a little more light on 55, and less light on 11, so hopefully we won't be saturating things anymore.
As I always tell everyone: Don't use a 10% reflector which produce ghost beams. Use a 90% reflector.
Hmmm, yes, I forgot (bad me). I'll find a 90% refl BS, and swap the positions of REFL11 and REFL55.
I have done the swap in the REFL path. First, I swapped the positions of REFL11 and REFL55. Then, I swapped out the 50/50 BS for a 90% reflection BS. (90% goes to REFL55, 10% goes to REFL11). I also changed the aluminum dump that was dumping the old REFL165 path into a razor dump.
Before: REFL11 had 4.0mW, REFL55 had 3.1mW. Now, REFL11 has 0.53mW, and REFL55 has 6.9mW. REFL165 still has around 61mW of light, and REFL33 has 3.3mW (the things that were changed were after 165 and 33 in the REFL path).
Now, the DC value of the REFL PDs are: REFL165 = 10.4V, REFL33 = 110mV, REFL55 = 232mV, REFL11 = 18.6mV.
As I was finishing aligning the beams onto all of the REFL diodes, Manasa asked for the IFO so she and Masayuki could continue their work on the Xarm, so I'll check the signals acquired a little later.
The DRMI has been locked!! And at least one time, it was for more than one minute!!
We are not 100% sure yet that it's correctly sideband locked. The test of this was to put a 50% BS in front of the AS camera (so after the beam has gone to AS55), and send the light over to a PDA10CF Thorlabs PD. I locked the Michelson on carrier for the alignment of this diode. Then I strung a cable to the control room, and plugged it into the RF spectrum analyzer. (First, I had turned off the green beat PD power, so there wasn't any RF stuff on the line that I unplugged). It's hard to watch the screen and a tv / dataviewer at the same time, so I've taken a video, so that we can see the nicely locked round DRMI beam on the AS camera, and the spectrum analyzer. My phone is working very hard at uploading the video, but we may have to wait until tomorrow for that. However, I think that we're locked on the 55MHz sideband. (Also, maybe I'm too tired or excited or something, but how do you make the real cameras take video??)
EDIT: Video uploaded. Pause the video at 10 seconds, and you'll see that we've got a strong 110MHz peak!! Hoooray! The TV in the upper right side of the video is AS. You can see as we flash, the peaks go up and down. When there's no resonance, the 110 peak goes away. (Ex., when I'm PRMI locked on the sideband, there isn't a visible peak).
Alignment procedure was as normal: Lock and align the arms. Misalign ETMs. Check that MICH fringes look good (ASS does a nice enough job that I don't actually lock and align the Michelson anymore). Restore the PRM. Lock PRMI. Tweak PRM alignment to maximize POP110I. At this point, Koji and I played a little with the PRMI, but when we finished with that, we restored the SRM, and tweaked its alignment by making nice overlap on the AS camera.
Then, we tried some DRMI settings, started seeing some locks, and played a bit with trying to optmize the settings that we have.
PRCL ASC is on (with loop triggering). MICH gain = -0.8, PRCL gain = +0.05. FM4, FM5 always on, FM2 triggered. Loop and filter module triggering on POP22I. No power normalization. MICH and PRCL locked on REFL55 I&Q, with 1's in the LSC input matrix. PRCL actuating on PRM with +1, MICH actuating on BS with +0.5, PRM with -0.267.
I took transfer functions between REFL55 I&Q and REFL11 I&Q, to determine the relative gains and signs. REFL11I's gain should be -18dB relative to REFL55I, with the opposite sign. We tried PRMI locking with MICH = 1*REFL55Q and PRCL = -0.125*REFL11I for the input matrix. Still no power normalization (we haven't used power norm at all today, so I'll quit writing that).
I took transfer functions between REFL55 I&Q and REFL33 I&Q. REFL33I's gain is -8dB relative to REFL55I, but they have the same sign. We tried locking PRMI with MICH = 1*REFL55Q and PRCL = +0.6*REFL33I. Success.
Next up, some Optickle simulations, to help us go in the right direction for DRMI locking. I checked the signs of the error signals REFL55I (PRM sweep), REFL11I (PRM sweep) and REFL55Q (MICH sweep) in both PRMI and DRMI configurations. For all of these cases, the signs were the same (i.e. no sign flips needed to happen for DRMI locking, relative to PRMI locking). I checked the sensing matrices for DRMI and PRMI for those same signals, and took the ratios of the sensing matrix elements. This gave me the ratio of optical gains for each error signal, in the DRMI case vs. PRMI case, so any servo gain changes should be the inverse of these numbers. These numbers are all DRMI/PRMI: REFL55I PRCL response = 0.76, REFL11I PRCL response = 0.99, REFL55Q MICH response = 18. So, when trying to lock the DRMI, we wanted to keep the gains for PRCL about the same, reduce the servo gain for MICH by a factor of ~20, but keep the same signs for everything.
In doing that, we started seeing some short DRMI locks, so we twiddled some parameters (mostly the elements in the LSC input matrix) a bit. We eventually settled on: PRCL = -0.125*REFL11I, MICH = 0.1*REFL55Q, and SRCL = 1.0 * REFL55I. The output matrix was the same (MICH pushing on BS and PRM, PRCL on PRM), with the addition of a +1 in the SRCL -> SRM element. For all 3 degrees of freedom (PRCL, MICH, SRCL), FMs 4 and 5 were always on. For PRCL, FMs 2,3,6 were triggered to come on after 0.5 seconds of delay. The PRCL FM triggers helped enormously. I tried several other things, including changing the MICH input matrix element up and down in value, changing the SRCL input matrix element up and down in value, and engaging triggering for a few different filters in the MICH and SRCL degrees of freedom. However, none of these made things better, and several made things worse. Most notably, for SRCL, engaging triggering for FMs 2 and 3 kicked the cavities out of lock, which implies that perhaps our gain isn't high enough yet (and thus our UGF isn't very high yet). I changed FM1 of SRCL to be +3dB of gain (from +10dB), and it would live through that coming on (trigger delayed by 1 sec, then ramping up over 1 second), but within a second after the filter finishing coming on, the cavity would fall out of lock (not violently kicked, just not locked anymore).
At this point, we were trying to figure out a way to confirm what kind of lock we had. I checked Optickle again, and we do not expect to see a significant change in POP110I between the PRMI and DRMI cases, so that isn't a useful check. We dreamed of having our AS110 demod board, or the AS OSA set up, but neither of those was going to happen tonight. Instead, Koji suggested hooking up the PD, and looking directly at the output.
To-do: Set up the AS OSA. Also, perhaps temporarily borrow the 110 demod board from POP. We were triggering on POP22 tonight, and that seemed to work okay.
Very nice!! I was wondering, shouldn't the driving matrix be such that MICH pushes on SRM as well?
Hmmm, yes, that's a very good point. I think you're right, and I'll give that a try today.
We were meditating a little bit on what may be the story behind the PRM violin filter situation. We locked the PRMI, and turned on and off the violin filters. We noticed, very bizarrely, that when the violin filters were ON, the servos would oscillate. Weird. Also, probably because the oscillation was causing us to hit the limit we have in the MICH servo, we rung up a 3rd harmonic of one of the violin modes, which was at 1955 Hz.
We took a transfer function of the PRCL servo, saw that the UGF was 300 Hz, and lowered it to ~180 Hz. After later investigations, that high-ish UGF probably wasn't a problem. Anyhow, we then took MICH servo transfer functions, and saw some very weird stuff.
At frequencies where we had violin filter notches, we were seeing peaks in the transfer function, which came close to touching, or crossed the 0dB line! We suspect that this may have something to do with the balancing of the drives to the optics, since we have PRCL driving PRM, but MICH driving BS and PRM. What we did was move the violin filter notches into the LSC model. There were already SUS filter banks in the LSC model (right side of the LSC screen). In preparation for the DRMI, I have put the BS violin notches into the BS, PRM and SRM filter banks, as well as the PRM and SRM filters into all 3 banks. Right now for PRMI, I have the BS and PRM notches (as well as the Vio3 notch) turned on in both BS and PRM. All of the violin-related filters are turned off in the LSC filter bank inside the SUS models. When we did this, the servo oscillations no longer are excited when we turn on the notches, and when we take a new transfer function, there are no longer weird peaks at the notch frequencies. More meditation needs to be done.
Also, for the violin3 filter, Rana noted that at 1955 Hz, after we confirmed that the REFL 55 phase was set correctly (and we're using REFL 55 I&Q for PRMI locking), the I-phase had a response of 0.36, while the Q-phase had a response of 0.20. I should be able to think about these numbers, and decide if the vio3 is for the BS or the PRM violin mode.
the above series of Bode plots shows the MICH Open Loop Gain as the REFL55 phase is adjusted (PURPLE, ORANGE) with the notches in the SUS and then (RED) as the notches are moved to the LSC and made the same for all optics.
In other news, I have the parts that Jamie ordered to make a new 110 demod board, so that's one of my daytime activities now, so we can have both POP110 and AS110.
I have modified one of the spare demod boards that was sitting above the electronics bench (the one which was unlabeled - the others say 33MHz, 55MHz and 165MHz) to be the new AS110 demod board. In place of the T1 coil, and the C3 and C6 resistors, I have put the commercial splitter PSCQ-2-120+. In place of U5 (the low pass for the PD input) I have put an SCLF-135+.
In order to figure out how to make the pinout of the PSCQ match up with the available pads from T1, I first pulled the "AS11" board (it's not something that we use, so it would be less of a tragedy if something happened while I had the board pulled). However, while the PCB layout is the same, the splitter for the low frequencies (PSCQ-2-51W) has a different pinout than the one I need for the 110MHz. So, I put AS11 back, and pulled the POP110 board. (After I noted the pinout on POP110, I reinstalled that board. To get it out, I had to unplug the I and Q outs of POP22, but I have also replugged those in).
For my new AS110 demod board, I copied the pin connections on POP110. I have made a little diagram, so you can see what pins went where. The top 2 rectangles are the "before" installation cartoon, and the bottom is the "as installed" cartoon.
The one thing that must be noted is that, because of the pinout of the splitter and the constraints of the board layout, the +0 degrees (I-phase) output of the splitter is connected to the Q channel for the rest of the demod board. This means that the +90 degrees (Q-phase) output of the splitter is connected to the I channel for the rest of the demod board. This is not noted for POP110, but is true for both: The I and Q channels of the 110 MHz demod boards are switched. In practice, we can handle this with our digital phase rotation.
Daytime tomorrow, I will test my new board as Suresh did in elog 4736. Before we get to use AS110, we need (a) some LO juice from the RF distribution box, and (b) a spot to plug the board in, in the LSC rack. Meditating on how those are going to happen are also tasks for daytime tomorrow.
I have made a measurement of the PRMI and the DRMI sensing matrices.
Keiko pointed out to me in an email a little while ago that I wasn't zeroing elements in the oscillator drive matrix after using them, so I was effectively driving all the degrees of freedom at once, which is why some of the recent sensing matrices looked a little bullshitty. Anyhow, I put in a few lines to zero that row of the LSC output matrix, so that we don't do that any more.
PRMI sensing matrix:
DRMI sensing matrix, first-ever measurement, after the optic flipping / recent locking success:
Note that we don't have any error bars in the DRMI case, since the IFO fell out of lock during the error bar measurements. So, we got the "real" data from the degrees of freedom, but not extra data for making error bars. Also, the MICH / SRCL coupling hasn't been balanced out in the output matrix yet, but since the notches are engaged in the degrees of freedom during this measurement, that shouldn't be a significant effect.
To get the DRMI sensing matrix measured, I added the SRM's actuator calibration to SensMatDefinitions.py (data from elog 5637). I also created a new file runDRMI_sens, to be the equivalent of runPRMI_sens. In the new runDRMI_sens, I reduced the actuation from the oscillator by a factor of 10. I had several attempts at higher oscillator amplitudes that kept kicking the IFO out of lock.
The DRMI was pretty good, but I wasn't getting ~10s of minutes like Koji was on Friday. I also wasn't able to engage all of the FM triggers that he was. The 10-30 Hz seismic BLRMS is a little higher than a usual night, but other than that, seismic looks pretty quiet.
My settings for the night:
LSC input matrix: +0.1*REFL55Q = MICH, -0.125*REFL11I = PRCL, +1.00*REFL55I = SRCL.
Filter settings: MICH, PRCL, SRCL all had FM4,5 always on. MICH had FM2,3 triggered. PRCL had FM2,3,6 triggered. SRCL had FM2 triggered. In particular, engaging FM 6 for MICH or SRCL made some loud low-ish frequency oscillation. Engaging anything other than FM2 for SRCL kicked the IFO out of lock.
Gains: MICH = -0.800, PRCL = +0.050, SRCL = -0.100
Triggering: All triggered on POP22I, upper = 50, lower = 10 (lower = 25 for SRCL).
FM trigger thresholds: MICH on = 35, off = 2, delay = 2 sec. PRCL on = 35, off = 2, delay = 0.5 seconds. SRCL on = 80, off = 25, delay = 5 sec.
Power normalization: None, for any degree of freedom.
LSC Output matrix: MICH = -0.267 for PRM, +0.50 for BS. PRCL = +1.0 for PRM. SRCL = +1.0 for SRM.
LSC SUS filters: BS, PRM, SRM all had FM1,2,3,6 engaged for the BS, PRM and SRM violin filters, as well as the 3rd order harmonic for one of them.
I tried locking the SRMI, so that I could do the same kind of actuator calibration that Koji did for the PRMI in elog 8816, but was unsuccessful. I checked optickle, and found that for REFL 55 I&Q locking, MICH and SRCL keep the same signs for SRMI as DRMI. Also, for both, the optical response is a factor of ~15 lower for SRMI than DRMI, so the gains should be higher by a factor of 15 for both MICH and SRCL. I think my big problem here is that I don't have anything to trigger on. There isn't any signal to speak of in the POP PDs, with the PRM misaligned. Hopefully we'll have AS110 shortly, and that will help.
I updated the IFO Configure restore scripts to our latest versions of locking. I have also tested them, and restoring the Michelson, PRMI and DRMI all seem to work. (MICH restores to locking with AS55Q. PRMI restores to locking with REFL165 I&Q. DRMI restores to the settings noted above in this entry.) The X and Y arm restores have been working, and I have been using them (semi-)regularly since I announced them in elog 8433 back in April. Still to-do though: Add PRCL ASC to the PRMI up script, and make the dither options work for at least the arms and PRM. (Just need to point the drop down menu options to the new ASS scripts.)