I have created a wiki page with introductory info about the summary page configuration: https://wiki-40m.ligo.caltech.edu/Daily summary help
We can also use that to collect tips for editing the configuration files, etc.
I have set up new summary pages for the 40m: http://www.ligo.caltech.edu/~misi/summary/
This website shows plots (time series, spectra, spectrograms, Rayleigh statistics) of relevant channels and is updated with new data every 30 min.
The content and structure of the pages is determined by configuration files stored in nodus:/users/public_html/gwsumm-ini/ . The code looks at all files in that directory matching c1*.ini. You can look at the c1hoft.ini file to see how this works. Besides, a quick guide to the format can be found here http://www.ligo.caltech.edu/~misi/iniguide.pdf
Please look at the pages and edit the config files to make them useful to you. The files are under version control, so don’t worry about breaking anything.
Do let me know if you have any questions (or leave a comment in the pages).
Thanks for the great entry!
In order to make this work for higher frequencies, I would add Hartmut's suggestion of a frequency dividing input stage. If we divide the input down by 100, the overall range will be about 200MHz, and the noise will be about 20Hz/rtHz. That might be good enough... but we can hope that the commercial device is lower noise!
Last Friday, Matt made a frequency discriminator circuit on a bread board in order to test the idea and study the noise level. I think it will work for phase lock acquisition of Green locking.
As a result a response of 100kHz/V and a noise level of 2uV/rtHz @ 10Hz are yielded. This corresponds to 0.2Hz/rtHz @ 10Hz.
The motivation of using frequency discriminators is that it makes a frequency range wider and easier for lock acquisition of PLLs in green locking experiment.
Today we tried the Schmitt trigger DFD, and while it works it does not improve the noise performance. At least part of our problem is coming from the discrete nature of our DFD algorithm, so I would propose that an industrious day job person codes up a new DFD which avoids switching. We can probably do this by mixing the input signal (after high-passing) with a time-delayed copy of itself... as we do now, but without the comparator. This has the disadvantage of giving an amplitude dependent output, but since we are working in the digital land we can DIVIDE. If we mix the signal with itself (without delay) to get a rectified version, and low-pass it a little, we can use this for normalization. The net result should be something like:
output = LP2[ s(t) * s(t - dt) / LP1[ s(t) * s(t) ]],
where s(t) is the high-passed input and LP is a low-pass filter. Remember not to divide by zero.
Power Spectral Density plot using PyNDS, comparing 5 fast data channels for ETMX.
**EDIT** Script here:
import numpy as np
import matplotlib.pyplot as plt
rqst=['C1:SUS-ETMX_SENSOR_UR','C1:SUS-ETMX_SENSOR_UL','C1:SUS-ETMX_SENSOR_LL','C1:SUS-ETMX_SENSOR_LR','C1:SUS-ETMX_SENSOR_SIDE'] #Requested Channels
for c in channels:
if c.name in rqst:
data=daq.fetch(start-100, start, c.name)
for x in np.arange(0,e):
plt.loglog(psdfreq0, 10*vars()['psddata'+str(x)], label=vars()['label'+str(x)])
Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.
There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.
You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.
The tiles were cut out in 1.5" ID circle to insure that the 7/16" OD lead balls would not touch the tiles on Wednesday, May 26, 2010
Granite surface plate specifications: grade B, 18" x 24" x 3" , 139 lbs
These balls and granite plate were removed by Rana in entry log #3018 at 5-31-2010
I tried to calculate the frequency of resonance using Rayleigh's method. approximated the geometry of lead to be that of a perfect cylinder, and the deformation in the lead by the deflection in a cantilever under a shear strain.
this rough calculation gives an answer of 170Hz and depends on the dimensions of each lead, number of leads, and mass of the granite. But the flaw pointed out is that this calculation doesnot depend on the dimension of the granite slab, nor on the exact placing of the lead spheres with respect toteh COM of the slab.
I will put up the calculations details later, and also try to do a FEM analysis of the problem.
BTW, latex launched this new thing for writing pdfs. doesnot require any installations. check http://docs.latexlab.org
i added my laptop's mac address to teh martian at port 13 today.
This week I attended a whole lot of orientations, lectures, and meetings related to SURF. Done with general and laser safety training.
read Nergis' thesis for, and other material on WFS.
got confused with how the sidebands and shifted carrier frequencies are chosen for the Interferometer, read initial chapters of Regehr's thesis for teh same.
Made a plan for proceeding with the WFS work through discussions with Koji.
Understood the MC cavity and drew a diagram for it and the sensors.
Did Calculations for Electric field amplitudes inside and outside the MC cavity.
Saw the hardware of the WFS and QPD inside, and their routes to computers. Figured out which computer shows up the conditioned data from teh sensors.
Tried calculating the cavity axis for MC using geometry and ray tracing. Too complicated to be done manually.
Read some material (mainly Seigman) for physics of calculating the eigen-axis of the MC cavity with mirrors mis-aligned. Will calculate that using simulations, using the ABCD matrices approach.
Made a simple feedback simulink model yesterday to learn simulink. Made it run/compile. Saw the behaviour thru time signals at different points.
in the night, Made a simulink model of the sensor-mirror thing, with transfer functions for everything as dummy TFs. Compiles, shows signals in time. Remaining part is to put in real/near-real TFs in the model.
Wednesday Morning E-log :
Most of the time through this week, i was working towards making the simulink model work.
It involved learning simulink functions better, and also improving on the knowledge of control theory in general, and control theory of our system.
1. Thusrday : found tfs for the feedback loop. and tried many different filters and gains to stabilize the system (using the transient response of the system). - not through
2. Friday : decided to use error response and nullify the steady state error instead of looking at convergence of output. tried many other filter functions for that.
Rana then showed me his files for WFS.
3. Sunday - played with rana's files, learnt how to club simluink with matlab, and also about how to plot tfs using bode plots in matlab.
4. Monday : Read about state-space models, and also how to linearize in matlab. done with the latter, but the former still needs deeper understanding.
read ray-optics theory to calculate the geometric sensing matrix.
It first requires to calculate the eigen mode of the cavity with tilted mirrors. this eigen mode is needed to be found out using ray-optics transfer matrices for the optics involved . figured out matrices for the tilted plane mirrors, and am working on computing the same for MC2.
5. Tuesday : went to Universal Studios , Hollywood :P
6. Wednesday (today) : Writing the report to be submitted to SFP.
Wednesday after the meeting - Started report, learnt mode cleaner locking from Kiwamu and Rana, saw how to move optics on the tables with Rana and kiwamu.
Thursday - Made the report
Tuesday - report.
Today - am trying locking the MC with kiwamu's help to see the WFS signals and also to start characterizing the QPD.
Nancy and Koji:
This is what I and Koji measured after aligning the MC in the afternoon.
MC_Trans 4.595 (avg)
MC_Refl 0.203 (avg)
power = 1.34mW
13.5% width : x=6747.8 +- 20.7 um , y = 6699.4+- 20.7 um
The WFS error signals were recorded in the order
these measurements are made in the linear region, that is the MC is nearly perfectly aligned.
This is the average and std. dev.of 5 measurements taken of the same signals over 10 secs each. The std. dev are under 10%. And hence, I will be using 10 secs for measurements for the WFS signals after perturbations to the mirrors.
I perturbed the Pitch and Yaw of the Three mirrors (in order MC1,2,3), using ezcastep and calculated the coefficients that relate these perturbations to the WFS error signals.
The perturbation made is of -0.01 in each dof , and after measuring the WFS error for it, the system is reverted back to the previous point before making the other perturbation.
I was able to calculate the coefficients since I have assumed a linear relationship..
Following are the coefficients calculated using 10 secs measurements
MC1_P MC1_Y MC2_P MC2_Y MC3_P MC3_Y constant
WFS1_PIT -0.1262 0.3677 -0.4539 -0.6297 -0.1889 -0.1356 0.013664
WFS1_YAW -0.0112 -0.7415 -0.1844 2.4509 -0.0023 -0.3531 -0.016199
WFS2_PIT 0.1251 0.4824 -0.2028 -0.6188 0.0099 -0.1490 0.006890
WFS2_YAW 0.0120 -0.7957 -0.1793 0.9962 -0.0493 0.2672 -0.013695
Also, I measured the same thing for 100s, and to my surprize, even the signs of coeficients are different.
MC1_P MC1_Y MC2_P MC2_Y MC3_P MC3_Y constant
WFS1_PIT -0.1981 0.3065 -0.6084 -0.9349 -0.4002 -0.3538 0.009796
WFS1_YAW 0.0607 -0.6977 0.0592 2.8753 0.3507 0.0373 -0.008194
WFS2_PIT 0.0690 0.4769 -0.2859 -0.7821 -0.1115 -0.2953 0.004150
WFS2_YAW 0.0580 -0.8153 -0.0937 1.1424 0.0650 0.4203 -0.010629
The reason I can understand is that the measurements were not made at the same time, and hence conditions might have changed.
A thing to note in all these coefficients is that they relate the error signals to the 'perturbation' around a certain point (given below). That point is assumed to lie in the linear region.
I and Koji were trying to lock the mode cleaner for measuring the beam power at MC2 end. That is when we obtained the trans and refl values.
The beam characteristics at the MC2 were measured so that we could now use a dummy beam of similar power to test and characterize the QPD we are about to install at the MC2 end. This QPD wil provide two more signals in pitch and yaw, and hence complete 6 signals for 6 rotatioanl dof of the cavity. (4 are coming from WFS).
Once the QPD is characterised, it can be used to see the spot position at MC2. This is related to the mirror angles.
The width measurements were done using a beam scan. the beam scan was properly adjusted so that the maxima of the intensity of the sopt was at its center.
We also fitted gaussian curve to the beam profile, and it was a substantially good fit.
The whole idea is that I am trying to look how the Wavefront sensors respond to the perturbations in the mirror angles. Once this is known, we should be able to control the mirror-movements.
the starting point would be to do just the DC measurements (which I did today). For proper analysis, AC measurements are obviously required.(will be done later).
The matrices so calculated can be inverted, and if found enough singular, the method can be used to control.
The first shot is to see teh dependency of teh error signals only on MC1 and MC3, and see if that is kind of enough to control these two mirrors.
If this works, the QPD signals could be used to control MC2 movements.
Hmm. I expect that you will put more details of the work tomorrow.
i.e. motivation, method, result (the previous entry is only this),
and some discussiona with how to do next.
I just found the singular values and the condition number of the 4*4 matrix relating the WFS error signals and the MC1 and MC2 movements.
I and koji setup the measurement of the QPD response to the pitch and yaw displacements of the beam spot.
We did this using a 100mW 1064nm laser. Its power was attenuated to ~ 1.9mW, and the spot size at the QPD position was 6000-7000 um .
The QPD was put on a translation stage, using which, the center of teh QPD wrt the beam spot could be moved in pitch and yaw.
Following are the measurements :
The slope of teh linear region is -8356 /inch
The slope of the linear region in this is 9085/inch
The old plots looked horrible, and so here is a new plot
The slopes and other stats are
Linear model Poly1:
f(x) = p1*x + p2
Coefficients (with 95% confidence bounds):
p1 = 8550 (7684, 9417)
p2 = -2148 (-2390, -1906)
Goodness of fit:
Adjusted R-square: 0.9907
Linear model Poly1:
f(x) = p1*x + p2
Coefficients (with 95% confidence bounds):
p1 = -8310 (-8958, -7662)
p2 = 2084 (1916, 2252)
Goodness of fit:
Adjusted R-square: 0.9945
For yesterday - July 12th.
Yesterday, I tried understanding the MEDM and the Dataviewer screens for the WFS.
I then also decided to play around with the sensing matrix put into the WFS control system and see what happens.
I changed the sensing matrix to completely random values, and for some of the very bad values, it even lost lock :P (i wanted that to happen)
Then I put in some values near to what it already had, and saw things again.
I also put in the matrix values that I had obtained from my DC calculations, which after Rana's explanation, I understand was silly.
Later I put back the original values, but the MC lock didnot come back to what it was earlier. Probably my changing the values took it out of the linear region. THE MATRIX NOW HAS ITS OLD VALUES.
I was observing the POwer Spectrum of teh WFS signals after changing the matrix values, but it turned out to be a flop, because I had not removed the mean while measuring them. I will do that again today, if we obtain the lock again (we suddenly lost MC lock badly some 20 minutes ago).
Summary of this week's work
Wednesday - Aligned the mode cleaner with Koji, and then measured the beam characteristics at MC2 end. Koji then taught me how to read the WFS signals
Thursday - wrote a script to measure the signals and calculated the coefficients relating mirror movement and DC signals of WFS. To know the possibility of the control, found SVD of the coeff matrix, and condition number.
Friday - Set up the measurement of QPD linear response using a laser outside the cavity. Took data.
Monday - did the calculations and plotting for the above experiment. Then played around with the MEDM screens , and also tried to see what happens to the Power Spectrum of WFS signals by changing the coefficients in teh matrix. (failed)
Tuesday - played around with WFS, tried seeing what it does when switched on at different points, and also what it does when I disturb the system while WFS has kept it locked.
I tuned the gain of WFS to 0 last night at about 3am.
I turned it back on now.
Yesterday I installed teh QPD on the table behind MC2, and observed teh signal on it.
The MC_leak is directed to it by a steering mirror.
I used the A2L_MC2 script to minimise teh pitch and yaw gains, and estimated teh spot position on teh MC2 using that.
This spot position was aligned to the center of teh QPD.
In the night while before taking measurements, I decided to turn off the Wavefront Sensor Servos, but just after that, the MC alignment went very bad, and I could not align it in the next 2 hours.
For some reason, the MC was really mad the whole day yesterday, and was getting misaligned again and again, even when the WFS feedback was on.
The table also had another IR laser in it, which I and Koji switched off.
I will continue measuring once we pump down again.
For now, I am analysing teh QPD circuit Transfer Function.
I turned the WFS gain to 0.02 back, and the MC is locked, the data for the seismic motion might be meaningful nowforth.
Yesterday, I started twiddling with the Mode Cleaner at about 2 pm.
So the seismic data should be all good before that.
I was using it till about 3.30 am, and then left for the night with locking it and swithcing on back the WFS control
Today morning, I have started twiddling with it again, at about 10.30 am.
About my work with the mode cleaner :
I am primarily exciting the mirrors in pitch and yaw, and trying to measure the response of the WFS and the MC2 OPLEV wrt the excitation.
This thus involves switching off the WFS control while measurement.
After two more of those measurements today, I will get to finding new values for the Output Matrix of the WFS for controlling MC1 & 3, and also, try giving in control to MC2 alignment using OPLEV signals.
TFs after the measurement -
In the order - MC1 , MC2 , MC3 -pitch and yaw.
These plots let us know about how do the wavefront sensor signals actually respond to the mis-alignments in the mirrors.
For legibility, legend has been includded in only one plot in each pdf., its typically the same for all 3 plots.
the actual xml files for this measurement are in the directory /cvs/cds/caltech/users/nancy/Align_Matrix/highpower/spot_center
It was made sure before each measurement that the MC is best aligned, the WFS are turned off, and the spots on all 3 QPDs are centered.
I calculated the MC1&3 Vs WFS1&2 Output Matrix today from the above measurements with koji's help.
the matrix can be generated from the m file at /cvs/cds/caltech/users/nancy/Align_Matrix/matrix.m
these values were put in, and the direction of control is sort of confirmed. I tried twiddling with the gains in the loop to get a 4*4 stable control, but could not succeed.
the mode cleaner is back locked now, and WFS matrix as well as gains are reverted to the old values. (1.30 am)
The output Matrices are
I realised today morning that there was a flaw in my calculations for the yaw matrix.
Correcting the values, and also making teh tables more readable.
I will test these values once our computers are back to working condition.
E-log entry for Friday - will attach more plots to this entry on wednesday after i am back to the 40.
The WFS and QPD servos were working. That was great.
Everything was fine except for the time series plots.
I could not get what story you are telling with the time series.
(e.g. your's are good or bad or anything)
Well, the data is kind of not enough to be analysed in time domain,
But by far from what I analyse, I think that the new control is not worse than the old one.
I donot also find any better results, except for this one being theoritically stronger.
Since the laser is off, Jenne and I rasied the chiller-chiller (small AC in the Control Room) set point temperature to 73 degree F (from 68F) to save people from shivering.
I have taken the charger for the dark gray dell laptop from its station, and have labelled the information there too.
Will keep it back tonight.
Friday night myself and Koji measured the Transfer function of the QPD circuit at MC2 side using a chopper . Following was our procedure :
We connected some wires at the input and output of the filter circuit to one of the segment of teh QPD. - seg 1.
A laser light was shined on to the QPD, it was pulsed using a chopper. The frequency of rotation of the chopper was varied.
These wires were then fed to the spectum analyser , and a transfer funstion was observed, It was nearly a low pass filter
The chopper frequency was then made variable by giving the chopper a signal from the spectrum analyser. This signal just swiped a large range of the rpm of the chopper.
Now the input signal looked like a sine wave of varying frequency. the transfer function looked like a perfect LPF, with a small SNR.
Attaching the plot of the TF in the next e-log (this one is on windows and can't access /cvs/cds)
We connected some wires at the input and output of teh filter circuit to one of the segment of teh QPD. - seg 2.
A laser light was shined on to the QPD, it was pulsed using a chopper. The frequency of rotation of teh chopper was varied.
The chopper frequency was then made variable by giving the chopper a signal from teh spectrum analyser. This signal just swiped a large range of the rpm of the chopper.
Now the input signal looked like a sine wave of varying frequency. the transfer functino looked like a perfect LPF, with a small SNR.
Attaching the plot of the TF in the next e-log (this one is on windows and cant access /cvs/cds)
Upon Nancy's request, I checked the status of the suspensions.
I found that the power strip of the 1Y4 rack was turned off.
Since it has a over current breaker, I don't know whether it happened by someone or over current.
Anyway, I restarted the sus computers, and now the suspensions are damping as usual.
The MC has been aligned, the auto locker is also working.
Incidentally, I found that the WFS servos are not working. Actually since the last night
It repeated losing lock and unlock.
Probably some values of the matrix or the gain is wrong.
I left the WFS as it is because Nancy will put new values this afternoon.
I will ask her to confirm that the old values work at the end of her work.
Yesterday , I put in the Output Matrix, and changed the gain sliders for the 4 WFS loops.
It worked and was keeping the lock for the MC.
I then tested whether the MC1 and 3 were following any change in MC2 alignment. It was indeed workinng,
Next we stepped to putting in the gains for the MC2 oplev servo.
the signs are decided on the basis of convergence, and the magnitude is kept very low, to have a very slow control for MC2.
This complete 6 * 6 model does work, and was able to keep the transmission held.
I also tried poking each mirror in pitcg and yaw, and the cavity comes back to high resonance after some time.
This time is indeed large if the poking is made for MC2, and the transmission comes back to normal after big oscillations.
I tried to measure the Open loop TFs for all these loops yesterday, but somehow could not find a correct excitation.
I will do it today.
Plan ahead :
1. Center the spot on MC2 and the QPD
2. Optimize the gains by looking at response to noise.
3. Measure Power Spectrum Density of each error signal.
EDIT: The script and template file have been moved to /opt/rtcds/caltech/c1/scripts/general/netgpibdata/
The NEW and IMPROVED script for remotely getting data from Agilent 4395A network analyzer is located at /users/nichin
This script is quite different from the one in Elog 10108 and fetches us both magnitude and phase. There is an added feature of setting the IF Bandwidth.
The network analyzer is located at crocetta.martian (192.168.113.108)
> python NWAG4395A_data_acq.py [filename.yml]
I connected a simple 2MHz Low pass filter between the modulation output and signal input of the NA and ran a scan from 100KHz to 20MHz. The script was run from Ottavia.
The expected plot was obtained and is attached here.
Setting up the RF switch in rack 1Y1 to select between required PDs and scripts to tell it which channel to choose over the Ethernet.
The main issue is that flipping PR3 induces considerable astigmatism.
Yes, at 45degrees PR3 will only have a curvature of about 850m for the vertical mode of the beam, apparently not enough to stabilize the cavity.
Still no good locking!
After making the reflected beam size closer to the injected one, I maximized alignment. I locked again in 00 mode, but I couldn't maximize the power.
I just realized that maybe I'm not using the correct radius of curvature for the ETMY in the simulation. Tomorrow I will start checking from that.
Also make sure you are taking into account the substrate of the ETM.
After restoring alignment I could see again strong 00 flashes (about 250-300 counts on ALS-TRY). So I locked the arm with IR and after enabling the PDH servo for the green locking, I also locked the green on the Y arm in 00 mode. Then I moved the two mode matching lenses to maximize the power into the 00 mode, but I didn't reach more than 30-35 counts.
Green power injected into the Y arm 0.680mW
Green power reflected back 0.090mW
Green power transmitted on the PSL few uW
I would expect more power on the PSL table (maybe 10x more).
Is this reflection measured with the cavity locked or unlocked?
So what's the actual designed reflectivity of the ETM for green? No one seems to be able to give me a straight answer about this.
Looking at the reflected beam when the beam is misaligned makes it look like it's << 0.9. Is that expected given the coating spec?
You say the cavity scan goes as high as 300cts but you can only lock to 30cts, are you locked on the sideband?
I'd repeat the measurement for REFL11. The PRC arrow has some big error bar on it, and maybe the true error is even bigger.
Also, please make the placement of the plots the same for modeled and measured so it's easy to compare.
The 785 analyzer in the 40 had a wonky hard to read screen. I was hoping that a new white CRT would fix all the problems.
I installed a white CRT, which didn't fix the wonkyness, but I adjusted the CRT position, brightness, focus settings to make the screen somewhat more readable.
If we want to send the thing in for service to fix the wonkyness, we should probably hold on to the old CRT because they will probably replace the whole screen assembly and we'll lose our white screen.
In order to better understand how the composite signal would behave in the presence of noise, I decided to do a simple analysis of the cavity signals while sweeping through resonance.
My noise model was to just assume that a given signal has some rms uncertainty (error bars) and use linear error propagation to propagate from simple signals to more complicated ones.
I used the python package uncertainties to do the error propagation.
I assumed that the ALS signal, the cavity transmission, and the cavity PDH error signal all have some constant noise that is independent of the cavity detuning. Below is a sweep through resonance (x axis is cavity detuning in units of radians).
The shaded region represents the error on each signal.
Next I calculated the 'first order' calculated error signals. These being a raw PDH, normalized PDH, an inverse square root trans, and the normal ALS again. I tuned the gains so they match appropriately.
Here, one can see how the error in the trans signal propagates to the normalized and trans signals and becomes large are the fractional error in the trans signal becomes large.
Next I did some optimization of linear combinations of these signals. I told the code to maximize the total signal to noise ratio, while ensuring that the overall signal had positive gain. I did this again as a function of the cavity detuning.
Each curve represents the optimized weight of the corresponding signal as a function of detuning.
So this is roughly doing what we expect, it prefers ALS far from the resonance, and PDH close to the resonance, while smoothly moving into square root trans in the middle.
It's a little fake, but it gives us an idea of what the 'best' we can do is.
Finally I used these weights to recombine the signals into a composite, to get an idea of the noise of the overall signal. At the same time, I plot the weighting proposed by Koji's mathematica notebook (using trans and 1-trans, and a hard switch to ALS).
So as one can see, at least for the noise levels I chose, the koji weighting is not much worse than the 'optimal' weighting. While it is much simpler.
The code for all this is in the svn at 40mSVN/nicolas/workspace/2014-03-06_compositeerror
in the elog
One feature that has been sorely missing in the elog has been the ability to easily add mathematical symbols. Here is an imperfect solution.
There is a browser plugin available for firefox, safari and chrome that allow you to add “markdown” formatting to any rich text input box in the browser. One feature of markdown is latex math formulae.
The way it works is you type some latex formatted math text in between dollar signs, click the button in your browser, and it converts them to rendered images.
The images are actually rendered through a google service, so if that service changes or goes down, the images won’t render, however the HTML source still contains the source string.
The size of formulae are not really matched to the text.
Going back and forth between rendered and unrendered can lose changes (if you make changes after rendering).
It also works in Gmail!
You can do code highlighting:
#!/bin/bash ### this is a comment PATH=$PATH:/home/user/path echo "How cool is this?"
EDIT: it looks like the code highlighting is sort of broken :-(.
Larry and Nicolas
Larry's transfer function measurements suddenly started returning 0dB 0degrees when before there was some fake filter in the C1:ALS-OFFSETTER2 filter bank.
We looked in the filter bank and his filter was gone. So I created a new filter called LARRYP in FM2. We also disabled the output so he could drive the filter bank and test his TF code.
I noticed today, and Rana said that he saw Saturday, that the MC refl value when the MC is unlocked is unusually high. It typically goes to about 4.5 V, but now is going up to 6.5V. Since the PMC output is the same as usual (max seen has been about 0.82 today), something must have happened between the PMC and the IMC.
Late last week, EricG and Nichin were looking at things on the AS table. Was anything touched on the AS table? Was anything touched on the PSL table? 'Fess up please, so that we can pinpoint what the change was.
Nope, we did not touch any of the PDs other than AS55. I have mentioned in my elog:10037 what we did exactly.
We just looked at all the other PDs to check if they were being illuminated by the correctly labeled fiber. Nothing other than that.
Actually, do we need to reset the filter history at every lock loss of the MC?
Those DC offsets were necessary to keep the alignment good just until the MC is unlocked.
So if we keep the history, we can maintain the good alignment.
I suspect the integrators get fed a huge wrong signal on lockloss. Clearing the history on the trans DOFs when the MC was badly aligned gets it nicely aligned again. I switched off the alignment transmission DOFs for now.
CFC-2X-C has a FIXED focal length of 2mm, but the collimator lens position is adjustable.
I'm not yet sure this affects your calculation or not as what you need is an approximate mode calculation;
once you couple the any amount of the beam into the fiber, you can actually measure it at the output of the fiber with a collimator attached.
I don't believe it had any effect, as all the calculations gave me the same target waist.
I don't know much about how the cron job runs, I'll forward this to Max.
I started to receive emails from cron every 15min. Is the email related to this? And is it normal? I never received these cron emails before when the sum-page was running.
Max says it should be fixed now. Have the emails stopped?
I don't know what had been wrong, but I could lock the PMC as usual.
The IMC got relocked by AutoLocker. I checked the LSC and confirmed at least Y arm could be locked just by turning on the LSC servos.
I could probably install the new fan if we have one. Can you do without the laser for a while?
This thread: ELOG 10295
My interpretation of these ELOGs is that we did not have the replacement, and then I brought unknown fan from WB. At the same time, Steve ordered replacement fans which we found in the blue tower yesterday.
The next action is to replace the internal fan, I believe.