Running train-of-thought elog:
East N2 cylinder found empty, replaced. West is >2kpsi
Removed Yuta-specific code from damprestore. A grep for 'yuta' in the python files within /scripts/ shows some other occurances, but nothing that is really in use at this time. New feature of damprestore.py: remembers oplev status.
WFS offsets relieved (all <20).
Adjusted FSS offset to minimize MC_FAST_MON
ASS ran (but the arm alignment has been astoundingly stable lately. I haven't touched it all this week)
ITMX is the only optic that got a correction over 20 counts.
BS and *TM oplev spots look well centered, except for ITMX.
I undid the gain reduction rana introduced because X ASS seemed to be really slow. It is currently fine in its older state. What's going on here?
Some network latency stuff is going on, even freezing up terminals when trying to write text files. This may (or may not) be correlated with the summary page rysnc jobs on nodus. It occurs to me that we have a DAQ ethernet network seperate from the martian network, but the frame transfers need to go through the martian network, since nodus is the only way out to the outside world. If we had a machine/gateway directly from the DAQ network to the caltech network, the martian network wouldn't get bogged down when frames are being uploaded
GTRY = 0.55, ok. Aligned GTRX to 0.52, also ok
Y beatnote was found easily. Have spent >30 minutes looking for X green beatnote. Typical FSS slow and X temperature ranges don't seem to be giving much. Will check the beat alignment with a scope, but if the beat is too high to begin with, it may not work...
I suspect a problem with the X Green BBPD
I could see the IR beatnote between the PSL and AUX X lasers at the input to the frequency counter. (I believe it is a real beatnote because it reacted as expected to the end temperature moving, and stabilizing the end laser to the arm). However, when placing the IR beatnote at a frequency which should've made the green beatnote visible on an analyzer and/or scope, no beatnote was found. I played with the beat alignment to no avail; the DC output of the BBPD behaved as expected, but I never saw anything in the RF output or on the control room analyzer. I also checked the beatnote signal chain by hooking up a 1mV 26MHz signal into the cable that hooks up to the RF out of the BBPD; the signal showed up clearly on the control room analyzer.
I'm not sure what may have happened. ELOG 9996 may be related.
I'm calling it a night.
Given my suspicion of fault with the X Green BBPD, Koji generously provided me with another one that he had confirmed to be working.
However, I turns out I was mistaken. With the existing BBPD, I did indeed witness a beat in the RF output, but it is somehow something like 20dBm smaller than it should be. This is why I missed it the other night. Here's a video of a RF output on a scope, wherein the beat is only barely visible because I've set the trigger level very low. I could not make the beatnote any larger through any alignment motions; I had gotten to this point by doing near/far field overlap on the PSL table.
I'm not sure what could have caused this. Mode mismatch? By eye, the beam spots looked about the same in the near and far fields, and we haven't had to touch the mode matching in quite some time... I've given up on trying to solve this for tonight.
Just for kicks, I hooked up the fiber PD IR beatnotes as inputs to the ALS DFD. The X beat is too small to even really see above the control room analyzer's noise floor, but the Y beat looked big enough. With the arms locked on IR, the phase tracker output RMS was a few kHz, so not even worth thinking about any further. Not so surprising.
Finally, I put back / hooked up everything in its nominal state.
I've started working on a general routine to measure noise couplings in our interferometers. Often this is done with swept sine measurements, but this misses the nonlinear part of the coupling, especially if the linear part is alreay reduced through some compensation or feedforward scheme. Rana suggested using a series of narrow band-limited noise injections.
The structure I'm working on is a python script that uses the AWG interface written by Chris W. to create the excitations. Afterwards, I calculate a series of PSD estimates from the data (i.e. a spectrogram), and apply a two-sample, unequal variance, t-test to test for statisically significant increases in the noise spectra to try and evaluate the nonlinear contriubutions to the noise. I've started a git repository at github.com/e-q/ifoCoupling with the code.
So far, I've tested one such injection of noise coupling from the ETMX oplev error point to the single arm length error signal. It's completely missing the user interface and structure to do a general series of measurements, but this is just organizational; I'm trying to get the math/science down first.
Here's a result from today:
Median, instead of the usual mean, PSDs are used throughout, to reject outliers/glitches.
The linear part of the coupling can be estimated using the coherence / spectrum height in the excitation band, but I'm not sure what the best what to present/paramerize the nonlinear parts of each individaul excitation band's result is.
Also, I anticipate being able to write an excitation auto-leveling routine, gradually increasing the exctiation level until the excited spectrum is some amount noisier than the baseline spectrum, up to some maximum amount configurable by the user.
The excitation shaping could probably be improved, too. It's currently and elliptic + butterworth bandpass for a sharp edge and rolloff.
I'm open to any thoughts and/or suggestions anyone may have!
Looks like a very handy code, especially with the real statistical tests.
I would make sure to use much smaller excitation amplitudes. Since the coupling is nonlinear, we expect that its only a good noise budget estimator when the excitation amplitude is less than a factor of 3 above the quiesscent excitation.
If so, or if not but you care about the signal that passes through these amplifiers, I suggest you remove this temporary power supply and wire the power from the rack power supplies through the fuse blocks and possibly use a voltage regulator.
In 24 hours, that power supply will be disconnected and the wires snipped if they are still there.
Steve has promised to add another row of fuses to the LSC rack first thing in the morning. Then, during Wednesday Chores, we can move the wires from the power supply to the fused power.
STEVE: NEVER MIND about doing this in the morning. Let's chat at the lunch meeting about what needs to be done to power things down, then back up again, in a nice order, and we can do it after lunch.
So, please do not do anything to the LSC rack tomorrow! Thank you.
I fixed the illuminator setup. ETMY was not hooked up, and the screen wasn't configured quite right. The ITMX illuminator still needs to be hooked up to the vertex switch.
I made an updated illuminator script that works more like the videoswitch scripts, with a saner interface, and is located here:
I also fixed up the illuminator MEDM interface a bit and added it to the VIDEO screen:
While I was at it, I cleaned up the sitemap a bit:
I hope everyone won't be too confused.
PSL, BS, ITMY and ETMX the illuminators were left on over night.
On VIDEO.adl, Image Capture and Video Capture did not seem to work and gave me some errors, so I fixed following two things:
1. just put one side of a USB cable to Pianosa the other side of which was connected to Sensoray; I don't know why but this was unconnected.
2. slightly fixed /users/sensoray/sdk_2253_1.2.2_linux/imsub/display-image.py as fpllows
L52: pix[j, i] = R, G, B -> pix[j, i] = int(R), int(G), int(B)
It seems to work, at least for some cameras including ETMYF and ITMYF.
Mike J. came tonight and he fixed Sensoray (elog #6645). He recompiled it and fixed it.
I made a python wrapper script for Sensoray scripts. It currently lives in /users/yuta/scripts/videocapture.py.
If you run something like
it saves image capture of AS to /users/yuta/scripts/SensorayCapture/ directory with the GPS time.
Below is the example output of AS when MI is aligned. We still see some clipping in the right. This clipping is there when one arm is mis-aligned and clipping moves together with the main beam spot. So, this might be from the incident beam, probably at the Faraday.
Currently, videocapture.py runs only on pianosa, since Sensoray 2253S is connected to pianosa. Also, it can only capture MON4. My script changes MON4 automatically.
We found that two of three PZT mirrors are at wrong place in the chambers.
Therefore we have to move these PZT mirrors together with their connections.
Here is a diagram for the current situation and the plan.
Basically mirror (A) must be associated to the output beam coming out from the SRM, but it was incorrectly put as a part of the input optics.
Similar to that, mirror (C) must belong to the input optics, but it is incorrectly being used as a part of OMC stuff.
Therefore we have to swap the positions of mirror (A) and mirror (C) as shown in the diagram above.
In addition to the mirror immigration, we also have to move their cables as well in order to keep the right functions.
We took a look at the length of the cables outside of the chambers in order to check if they are long enough or not.
And we found that the cables from c1asc (green line in the diagram) is not long enough, so we will put an extension D-sub cable.
The validation for high impedance measurement has been well done.
The impedance measurement is one of the keys for designing the EOM circuit.
So far I was very struggling to measure the high impedance ( above several 1000 Ohm) at RF because the EOM circuit has a high impedance at its resonance.
Finally I realized that the measured impedance was suppressed by a parasitic resistance, which especially reduces the impedance at the resonance.
Also I found that we can extract the TRUE impedance data by subtracting the effect of the parasitic resistance from resultant data.
In order to confirm whether this subtraction works correctly or not, the impedance was directly re-measured with another analyzer for crosscheck.
The measurement has been performed with help from Peter and Frank. ( Thank you !)
By using network analyzer AG4395A with the impedance test kit AG43961A (these are at the PSL lab.), the impedance of resonant circuit with EOM was measured.
The picture of setup is attached. This impedance test kit allows to measure typically 0.1 [Ohm]-1M [Ohm] and frequency range of 100kHz-500MHz.
The resultant plot is attached. In the plot the blue curve represents the impedance measured by usual analyzer at 40m.
Note this curve is already subtracted the effect of the parasitic resistance.
( the parasitic resistance is in parallel to the circuit and it has ~7.8k Ohm, which is measured while the probe of the analyzer stays open. )
The red curve is the re-measured data using the impedance test kit.
The important point is that; these two peak values at the resonance around 40MHz show good agreement in 10%.
The resonant frequencies for two data differs a little bit, which might be the effect of a stray capacitance ( ~several [pF] )
The red curve has a structure around 80MHz, I think this comes from the non-coaxial cables, which connect the circuit and analyzing kit.
You can see these cables colored black and red in the picture.
( conclusion )
Our measurement with the subtraction of the parasitic resistance effect is working reliably !
The shape of the beam spot in the new input optics got much much better
As Alberto and Kiwamu found on the last week, the beam spot after MMT1 had not been good. So far we postponed the mode measurement due to this bad beam profile.
Today after we did several things in the vacuum chamber, the beam spot became really a good Gaussian spot. See the attachment below.
There were two problems which had caused the bad profile:
(1) a steering mirror after MMT1 with the incident angle of non 45 deg
(2) clipping at the Faraday.
Also MCT_QPD and MCT_CCD were recovered from misalignment
Tomorrow we are going to restart the mode matching.
(what we did)
* We started from checking the shape of the beam going out from the BS chamber. There still were some stripes which looked like an interference on the spot.
* We found a steering mirror after MMT1 had the incident angle of non 45 deg. In fact the mirror had a large transmission. After we made the angle roughly 45 deg, the stripes disappeared.
However the spot still didn't look a good Gaussian, it looked slightly having a bump on the horizontal profile.
* Prior to moving of some optics in the vacuum, we ran the A2L_MC scripts in order to check the beam axis. And it was okay.
* To recover the MCT, we steered one of the vacuum mirrors which was located after the pick off mirror. And after aligning some optics on the AP table, finally we got MCT recovered.
* We rearranged MC_refl mirrors according to the new optical layout that Koji has made. At the same time the mirrors for IFO_refl was also rearranged coarsely.
* We leveled the optical table of the MC chamber by moving some weights. Then we locked the MC again and aligned it. We again confirmed that the beam axis was still fine by running the A2L scripts.
* We found the beam going through Faraday was off-centered by ~5mm toward the west. So we moved it so that the beam propagates on the center of it.
* Then looking at the beam profile after MMT1, we found that the profile became really nicer. It showed a beautiful Gaussian.
In the attachment below, the top panel represents the horizontal profile and the bottom one represents the vertical profile.
The blue curves overlaid on the plot are fitted Gaussian profile, showing beautiful agreements with the measured profile.
Y arm green transmission to the PSL table improved from ~ 20 uW to 61 uW. Improvement was done by adjusting steering mirrors before and after the faraday on the Y end table.
But 61 uW is not enough!
What I did:
1. The incident power to the faraday for the green beam on the Y end table was 1.4 mW, but the transmission was 1.2 mW. So, I adjusted the steering mirrors and the transmission increased to 1.4 mW.
2. I found that adjusting the steering mirrors to the faraday also increased alignment of the green beam to the Y arm. We always adjusted only the steering mirrors after the faraday for the alignment. I adjusted the alignment using both steering mirrors this time. Reflection of the green beam on the ETMYT camera seems more reasonable now and more frequently lock to TEM00 when closing and opening the Y end green servo loop.
3. For the adjustment, I tried to utilize PD at the reflection port, or the transmission port. However, I couldn't do that because they fluctuates too much. I don't know why.
4. Measured the green transmission to the PSL table, The transmitted power was ~20 uW, but after the aligning, it improved to 61 uW.
Current green power:
I measured the green beam power at various places using Newport power meter (Model 840) with its filter on.
Incident green power to the Y arm is ~ 1 mW (more than 1 mW because the aparture of the power meter was smaller than the beam size) and Y arm transmission is designed to be 55%. So, if the alignment and mode matching are perfect, the transmission to the PSL table should be ~ 600 uW. The measured value 61 uW seems too small. Kiwamu says it was 140 uW when he did Y arm.
I will find the beat note again tonight and check if the beat PD is working correctly and if the mode matching of the two beams at the PSL table is good.
We improved the Y arm green transmission to the PSL table. It is now 197 uW.
The improvement was done mainly by adjusting the Y arm green servo gain.
What we did:
1. Fine-adjusted steering mirrors after the faraday on Y end table by monitoring Y arm green transmission (used Thorlabs PDA36A as a PD, C1:GCV-GREEN_TRY as a channel). We decided which way to adjust the mirrors by just pushing/pulling its mount.
2. The output of the reflection PD on the oscilloscope seemed like the Y end frequency servo was oscillating. So, we reduced the amplitude of the frequency modulation from 2.83 V to 0.13 V.
3. We noticed there were two TEM00, one is brighter and the other is dim. We thought this came from a mode-hopping or something. So, we changed the Y end laser temperature from 34.68 deg C to 34.13 deg C (measured). This reduced dim TEM00 and the main one got brighter. C1:GCY-SLOW_SERVO2_OFFSET was changed from 29425 to 29845.
4. Fine-adjusted the position of the mode-matching lens by reduing LG modes.
Current green power:
Current measured green power values are as follows.
Calculated value for the Y arm green transmission is ~ 600 uW, but we think we are almost at the maximum we can get. So, we have about 70% loss from the Y end table to the PSL table. There may be large loss in windows. The beam shape of the transmitted beam seems OK, but there may be some clipping.
- Fine tune the Y end frequency servo loop. Reducing the amplitude of the frequency modulation for reducing the gain is not a very good idea.
Yes. The end PDH servo should be checked more carefully.
The end PDH seems to have insufficient gain at around 100Hz.
The attached is the ALS noise budget calculated with the simulink model for the green locking paper.
The residual error of the end AUX laser (green) is contributing to the final ALS signal (black).
In particular, the residual AUX frequency noise, which is shown as the blue, is contributing to the noise above 100Hz.
In the model I also confirmed that the servo still has a room for improvement.
By having more suppression of the AUX frequency noise, we will be able to increase the ALS servo bandwidth
without increasing the ALS residual RMS by a servo bump. This will give us the improvement of the seismic
noise suppression at 10Hz (i.e. more suppression of red).
I did the following today to prepare for taking the doors off tomorrow.
I am leaving all shutters closed overnight.
So I think we are ready to take the doors off at 8am tomorrow morning, unless anyone thinks there are any further checks to be done first.
Should we look to do anything else now? One thing that comes to mind is should we install ITM baffles? Or would this be more invasive than necessary for this vent?
Steve reported to me that he was unable to ssh into the control room machines from the laptops at the Xend and near the vacuum rack. The problem was with pianosa being frozen up. I did a manual reboot of pianosa and was able to ssh into it from both laptops just now.
Two different measurement have been performed for a test of the green locking last night.
Everything is getting better. yes. yes.
[ measurement 1 : IR locking]
The X arm was locked by using the IR PDH signal as usual (#4239, #4268) .
The in-loop signal at from the IR path and the out-of-loop signal at from the green beat note path were measured.
Let us look at the purple curve. This is an out-of-loop measurement by looking at the green beat note fluctuation.
The rms down to 0.1 Hz used to be something like 60 kHz (see here), but now it went down to approximately 2 kHz. Good.
This rms corresponds to displacement of about 260 pm of the X arm. This is barely within the line width. The line width is about 1 nm.
[ measurement 2 : green locking]
The motion of the X arm was suppressed by using the green beat signal and feeding it back to ETMX.
After engaging the ALS servo, I brought the cavity length to the resonance by changing the feedback offset from epics.
Then took the spectra of the in-loop signal at the beat path and the out-of-loop signal at the IR PDH path.
Here is a time series of TRX after I brought it to the resonance.
TRX was hovering around at the maximum power, which is 144 counts.
Since I put one more 10:1 filter to suppress the noise around 3 Hz, the rms of the in-loop beat spectrum went to about 1 kHz, which used to be 2 kHz (see #4341).
But the out-of-loop (IR PDH signal) showed bigger noise by a factor of 2 approximately over frequency range of from 2 Hz to 2 Hz. The resultant rms is 2.7 kHz.
The rms is primarily dominated by a peak at 22 Hz (roll mode ?).
I calibrated the IR PDH signal by taking the peak to peak signal assuming the finesse of the cavity is 450 for IR. May need a cooler calibration.
We need short cables that mirror the pins:
The male side will plug into the 25-pin female on the stack-top bracket. The tip-tilt quadrapus cable will plug into the female side. This will match up pin 1 on the tip-tilt cable, which is connected to it's shield, to pin 13 on the bracket, which is the shield of the cable that runs to the stack.
They need to be vacuum compatible. Shorter length is preferred, and there is no minimum length (something like an all-in-one gender changer would be ideal, but probably expensive to have made).
Accu-Glass is closed till Jan 2, 2013
Atm2 would be the ideal solution Gender Adaptor Special with male - female sides and vented D-sub. How many are we getting 2 or 6 ?
Opened ETMY, beam was high and to the right (if you look at the face of ETMY). Tried walking beam up, since just doing PZT2 caused clipping at the BS before we got to the correct spot on ETMY. Moved PZT1, then PZT2, to translate beam, but we couldn't get far enough without starting to fall off of PZT2. Put PZT1 approx. back where it was. Jamie tapped on the top of PR3 (tip tilt just before BS), and then did some compensation with PZT2 to get the beam through the BS target to the center of ETMY.
The beam is very dim at ETMY. We ended up holding the big IR card with holes such that one of the holes was near the center of the optic, in front of the cage. Then one person turned off all the room lights so we could see the beam, another person moved PZT2 and PR3, then lights person turned on and off the lights so we could compare beam position with hole position. A total pain, but it ended up working better than just trying to follow the beam with a card.
We clearly need a better plan for adjusting the tip tilts in pitch, because utilizing their hysteresis is ridiculous. Koji and Steve are thinking up a set of options, but so far it seems as though all of those options should wait for our next "big" vent. So for now, we have just done alignment by poking the tip tilt.
Tomorrow, we want to open up the MC doors, open up ETMY, and look to see where the beam is on the optic. I am concerned that the hysteresis will relax over a long ( >1hour ) time scale, and we'll loose our pointing. After that, we should touch the table enough to trip the BS, PRM optics, since Koji is concerned that perhaps the tip tilt will move in an earthquake. Jamie mentioned that he had to poke the tip tilt a pretty reasonable amount to get it to change a noticeable amount at ETMY, so we suspect that an earthquake won't be a problem, but we will check anyway.
After doing all of that, we adjusted IPANG so that the beam gets out of the vacuum envelope. The beam must squeeze between the wall of the black beam tube and a lens for the oplev, so there is a very, very limited amount of space. The eventual new tables will be very helpful for alleviating this, but for now we must live with it. Even though it is pretty squishy right at the edge of the table, with the new layout we should think about giving IPANG a little more space. Basically, if there is any Yaw motion, the beam going to the QPD will be clipped, and we may get confusing info. We moved some of the IPANG optics that are on the end transmission table so the beam is centered on the optics while it just makes it through the space between the wall and the lens. The spot was centered on the IPANG QPD.
We still need to check on IPPOS, but it is always easier than IPANG.
We discovered that the 45deg SOS beam targets are awesome, especially the ones with the irises. The plain hole ones have very small holes relative to our beam size, so they are much more useful for the MC optics (which they were designed for). The 45deg targets were made such that the target holes do not line up with the mounting holes. This is good, since the mounting holes are lower than the center of the optic. I don't think ericQ and I realized that on Friday, so it's probable that we had installed the target upside-down. We still need to remake the 0deg targets for the next vent.
Jamie dogged down the new 'bathroom mirror' that lets us see BS and PRM on the same camera view. He also adjusted some of the masses on the BS table to relevel the table. We need to (at some point) rename the AS_SPARE camera to something like BS_PRM, since we plugged the new camera into the AS_SPARE port on the videoswitch.
tl;dr: Input beam adjusted so we're hitting center of ETMY. IPANG coming out of vacuum, QPD centered. Need better tip tilt in-situ adjustment capability.
[Kieko / Kiwamu]
The AS beam shows a little bit of clipping and right now this is the only concern for the alignment of the interferometer.
Other than that everything is okay including :
+ Beam centering on all the suspended optics
+ Arm cavity alignments. The Fabry-Perot fringes from both arm cavity were found on the AS camera.
+ POX/POY/POP, they are still successfully coming out from the chambers
+ Alignment of the green beams and the associated optics. Both green are reaching to the PSL table
We need to check/fix the AS beam clipping and once it's done we will readjust the OSEM mid range and the oplevs.
Then it will be ready for the drag/wipe and door closing.
We will pump down the chambers on Thursday morning.
Today will be a day of the OSEM and oplev party.
-- to do list for today --
+ OSEM mid-range adjustment
+ oplev realignment
+ placement of beam traps
+ extraction of IPPOS
+ table leveling
+ interferometer alignment
+ AM-PM mystery
+ preparation for drag and wipe
We will pump down the chambers on Thursday Friday morning.
All hands on deck at 9am Thursday for drag wiping and doors. We'll do the 5 doors first (including drag wiping), then put on the access connector last. Steve will then begin pumping early Friday morning.
We will move on to the vertex region today.
The goal of the vertex region work is to get the pick-off beams out the chambers, including POX/Y and POP.
The work will be in parallel to the ETM woks.
The first step will be : lock and align MC with the IR beam.
This morning Kiwamu and I have aligned the MC. Kiwamu aligned the last steering (on the OMC table) to recover the touch last week.
Then I have aligned the MC with MC1 and MC3 as the last steering did not help to get TEM00.
C1:SUS-MC1_PIT_COMM = 2.6587
C1:SUS-MC1_YAW_COMM = 2.7471
C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.876
C1:SUS-MC3_YAW_COMM = 1.2829
C1:SUS-MC1_PIT_COMM = 2.7596
C1:SUS-MC1_YAW_COMM = 2.6627
C1:SUS-MC2_PIT_COMM = 3.486
C1:SUS-MC2_YAW_COMM = -1.1592
C1:SUS-MC3_PIT_COMM = -1.697
C1:SUS-MC3_YAW_COMM = 1.2901
This afternoon's work:
TODO before drag wiping:
A few things that I have neglected to ELOG yet:
scripts/offsets/LSCoffsets is a new script that uses ezcaservo to set FM offsets of our LSC PDs. It still warns about large changes, and lets you revert. It reads the FM gain to pick the right gain for the ezcaservo call.
We never, ever want to use ezcaservo to do this. IN fact, we twice have already deleted scripts where people have implemented these (sometimes) unstable servos. Also, since this change had never been committed to the SVN, I just deleted it and updated from the SVN to get back the script that doesn't use any servos.
I'm going to periodically delete locking scripts that are not committed to the SVN since anyone who is too lazy to use the SVN probably can't write code worth using.
The restored offset script used old tdsavg calls that our workstations can't do, and didn't include things like the transmon QPDs. I've written yet another offset script that uses cdsutils averaging to do the thing, and committed to the svn.
Is there a reason to use non-45 degree incident angles on the steering mirrors between the laser and the PD? I would always use 45 degree incident angles unless there is a really good reason not to.
Actually not, it is a mistake! It is one of the things I'm going to modify, in addition to add more BS to reduce the power.
Since the MC wasn't able to capture the 00 mode in this morning I aligned the incident beam going to MC.
As a result C1:IOO-RFPD_DCMON went down to 0.6. However the beam on IPPOS is almost falling off from the QPD.
I replaced the final steering mirror (Y1-1037-45-S) in the zig-zag path on the PSL table by a 0 deg mirror Y1-1037-0.
With a sensor card I confirmed the transmission reduced a lot after the replacement.
As we expected, the replacement of the mirror caused a mis-alignment of the incident beam axis to the MC, so I compensated it by touching the angle of the mirror a little bit.
After the alignment of the mirror, the MC is still resonating at TEM00.
We will check the spot positions more accurately by A2L technique.
- Y1-45S has 4% of transmission. Definitively we like to use Y1-0 or anything else. There must be the replaced mirror.
I think Suresh replaced it. So he must remember wher it is.
Frustrated by the single pixel width of the windows and how hard that makes it to drag things around, I explored StackExchange:
which showed how there is a .xml file which can be edited to increase this. I've changed the border size to 4 pixels on Rossa - its nice.
I maximized the laser power by rotating the HWP after the NPRO.
If someone works on the MC locking, one should decrease it again.
I wonder what's drifting between the laser and the PMC? And why is it getting worse lately?
The PMC refl is bad in pitch today, and the transmission is only 0.76, rather than our usual 0.83ish.
I did a quick, rough tweak-up of the alignment, and now we're at 0.825 in transmission.
I changed the input channels of the DMF recently so that it now uses 3 Guralp channels in addition to the 3 ACC and 1 Ranger.
op440m:seisblrms>diff seisBLRMS-datachans.txt~ seisBLRMS-datachans.txt
The seisBLRMS channels still have the wrong names of IX and EX, but I have chosen to keep them like this so that we have a long trend. When looking at the historical seisBLRMS trend, we just have to remember that all of the sensors have been around the MC since last summer.
Last night Rob ran senseDRM and loadDRMImatrixData and came up with the following for the input matrix:
tdswrite C1:LSC-ITMTRX_b2 0.065778 \
C1:LSC-ITMTRX_d2 2.2709 \
C1:LSC-ITMTRX_f2 2.9361 \
C1:LSC-ITMTRX_122 0.42826 \
C1:LSC-ITMTRX_b3 -0.064839 \
C1:LSC-ITMTRX_d3 -0.016913 \
C1:LSC-ITMTRX_f3 -0.021576 \
C1:LSC-ITMTRX_123 -0.0025243 \
C1:LSC-ITMTRX_b5 0.3719 \
C1:LSC-ITMTRX_d5 1.3109 \
C1:LSC-ITMTRX_f5 -0.16412 \
C1:LSC-ITMTRX_125 0.39574 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
Today, I reran these and got the following, and DD_handoff remained happy:
tdswrite C1:LSC-ITMTRX_b2 -0.10329 \
C1:LSC-ITMTRX_d2 2.0344 \
C1:LSC-ITMTRX_f2 3.2804 \
C1:LSC-ITMTRX_122 0.22516 \
C1:LSC-ITMTRX_b3 -0.076292 \
C1:LSC-ITMTRX_d3 -0.014603 \
C1:LSC-ITMTRX_f3 -0.12101 \
C1:LSC-ITMTRX_123 0.0054128 \
C1:LSC-ITMTRX_b5 0.33521 \
C1:LSC-ITMTRX_d5 1.1425 \
C1:LSC-ITMTRX_f5 -0.32759 \
C1:LSC-ITMTRX_125 0.25877 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
I wanted to remeasure with the canonical output matrix (-0.7 from MICH to PRM and 0.7 from MICH to SRM), but the DRM freaked out when MICH to PRM went below -0.3.
We improved the active tip-tilt (TT) controllers such that they now have filter banks at the PIT/YAW inputs, and at the coil outputs:
This allowed us to do a couple of things:
These are all big improvements. The TT MEDM screens were appropriately updated.
We had to rebuild/restart c1ass, which reset the TT pointing. We recorded all the values before hand and were able to recover the pointing easily. Interestingly, there did appear to be hysteresis in pitch, which is maybe not entirely unexpected, but still worth nothing.
[Yuta, Koji, Jamie]
We went into ITMX chamber to inspect the situation there. We looked for clipping and flipping at PR2, and found none, although we noticed that the beam at PR2 looks a little clipped.
We then went back into the BS chamber and took a closer look at the beam incident on PRM, and the situation with PR3. The PRM incident beam looked a little clipped, which we expected from the PR2 observation. But the beam looks well centered on PRM and PR3. As best I could tell the beam is reflecting off the front surface of PR3, as expected.
Looking at the beam around MMT1 and PJ2 (the second PZT on BS), we could tell that the beam incident and reflected off of MMT1 looked round, where as the beam incident on PJ2 looked clipped. Using my tallness super power I was able to reach into the IMC chamber and confirm that the beam going from MMT1 to MMT2 clips fairly badly on the edge of the Faraday. Koji speculates that this is the result of a misalignment of the PSL output beam into the MC. In any event, it's not clear how this would be the cause of our PRC woes.
We decided to close up for the night, and let Yuta work on aligning PRMI. We need to figure out what the heck to do now.
We've been watching the input power reduce, from 18 mW initially when we first went in, to about 5mW now. It seems to be leveling out now. It's unclear what would have been causing it. Drift of the input polarization?
We could set up a simple pick off after the Faraday and bring it out the north window of IOO chamber. No monitor needed, just take the cover off when you want to see it.
Most people have no idea how to get the MC through the F
I am installing an OSA on the AP table and it's ongoing.
I am leaving some stuff scattered on the AP table and I will resume the work after I come back.
I found that the DC monitor of the REFL165 was showing 9 V regardless of how much laser power goes to the diode.
I am worried about whether the RF output is also broken.
It needs to be checked and I will leave this to Suresh as one of his morning tasks.