||Thu Jun 26 18:27:04 2008
||rana||Update||Computer Scripts / Programs||No Dataviewer No Cry|
|Dataviewer was hanging. It would open the Grace window but then not plot anything. Since DTT was working|
fine we diagnosed this as a DV only problem. It turned out that there was a boatload of messages in the
dataviewer queue. You can check for extra messaages using the command 'ipcs -q' and then use 'rmq' to remove them.
Dataviewer is working now.
Here's the screen dump from op440m:
IPC status from <running system> as of Thu Jun 26 18:19:32 PDT 2008
T ID KEY MODE OWNER GROUP
q 400 0x1a51 -Rrw-rw-rw- controls staff
q 1 0x501 -Rrw-rw-rw- controls staff
q 2 0x512 -Rrw-rw-rw- controls staff
q 103 0x553 -Rrw-rw-rw- controls staff
q 4 0x574 -Rrw-rw-rw- controls staff
q 5 0x18be --rw-rw-rw- controls staff
q 56 0x1d9f -Rrw-rw-rw- controls staff
q 7 0x1e56 -Rrw-rw-rw- controls staff
q 8 0x1efd -Rrw-rw-rw- controls staff
q 109 0x2044 -Rrw-rw-rw- controls staff
q 10 0x207a -Rrw-rw-rw- controls staff
q 11 0x24c4 -Rrw-rw-rw- controls staff
q 12 0x24d7 -Rrw-rw-rw- controls staff
q 13 0x251b -Rrw-rw-rw- controls staff
q 14 0x2fe8 -Rrw-rw-rw- controls staff
q 115 0x3a65 -Rrw-rw-rw- controls staff
q 116 0x967 -Rrw-rw-rw- controls staff
q 17 0x98e -Rrw-rw-rw- controls staff
q 118 0x456c -Rrw-rw-rw- controls staff
q 669 0x194 -Rrw-rw-rw- controls staff
q 620 0xe70 -Rrw-rw-rw- controls staff
q 71 0x15d0 -Rrw-rw-rw- controls staff
q 222 0x3586 -Rrw-rw-rw- controls staff
q 173 0x5e37 -Rrw-rw-rw- controls staff
q 624 0x5e4d -Rrw-rw-rw- controls staff
q 475 0x10d7 -Rrw-rw-rw- controls staff
q 176 0x5ee3 -Rrw-rw-rw- controls staff
q 277 0x4e22 -Rrw-rw-rw- controls staff
q 428 0x25f3 -Rrw-rw-rw- controls staff
q 29 0x3354 -Rrw-rw-rw- controls staff
q 180 0x368f -Rrw-rw-rw- controls staff
q 131 0xb0f -Rrw-rw-rw- controls staff
q 82 0x47a5 --rw-rw-rw- controls staff
q 83 0x4b83 -Rrw-rw-rw- controls staff
q 34 0x4f6d -Rrw-rw-rw- controls staff
q 85 0x4539 -Rrw-rw-rw- controls staff
q 86 0x67a1 --rw-rw-rw- controls staff
q 37 0x4b7 -Rrw-rw-rw- controls staff
q 38 0xd37 -Rrw-rw-rw- controls staff
q 39 0x156c -Rrw-rw-rw- controls staff
q 40 0x2b62 -Rrw-rw-rw- controls staff
Deleting message queues which are owned by user: controls ....
Deleted message queue: 400
Deleted message queue: 1
Deleted message queue: 2
Deleted message queue: 103
Deleted message queue: 4
Deleted message queue: 5
Deleted message queue: 56
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Deleted message queue: 115
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Deleted message queue: 17
Deleted message queue: 118
Deleted message queue: 669
Deleted message queue: 620
Deleted message queue: 71
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Deleted message queue: 173
Deleted message queue: 624
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Deleted message queue: 428
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Deleted message queue: 40
||Thu Jun 26 18:24:28 2008
||Yoichi||Update||PSL||FSS input ofset slider problem - fixed|
|I checked the FSS servo interface board and found that a LT1125CSW used to differentialize offset channel was broken (no virtual short).|
So I replaced it. Now the slider is working.
The op-amp was hitting the rail. So it seems like we had been applying the maximum offset to the FSS input all the time.
The reason why the FSS loop still worked with the large offset is that the applied offset (~14V) is attenuated by a factor of 500 at the summing point.
||Thu Jun 26 14:06:00 2008
||Masha||Update||General||500mW INNOLIGHT NPRO info|
|Below is the placement of 500mW INNOLIGHT NPRO mephisto laser. It is set up on the Symmetric Port table. |
||Thu Jun 26 12:30:40 2008
||John||Summary||Locking||CARM on REFL_DC|
Try REFL_DC as the error signal for CARM rather than PO_DC.
The PO signal is dominated by sideband light when the arms are detuned so that any misalignment in the recycling cavity introduces spurious signals. Also, the transfer function from coupled cavity excitation to REFL signal is not so steep and hence REFL should give a little more phase. Finally, the slope of the REFL signal should make it easier to hand over to RF CARM.
The REFL signal showed no clear improvement over PO signals. We've gone back to PO.
During the night we also discovered that the LO for the MC loop is low.
||Thu Jun 26 10:56:15 2008
||Max Jones||Update||PEM||Removed Magnetometer|
|I removed the Bartington Magnetometer on the x arm to one of the outside benches. I'll be trying to determine if and how it works today. It makes a horrible high pitched sound which is due to the fact that the battery is probably 16 yrs old. It still works with ac power though and I want to see if it is still operating correctly before I ask to buy a new battery. Sorry for the bother. |
||Thu Jun 26 01:10:18 2008
||rana||Update||PEM||Alarm Handler indicates that dust level is high|
|In its first useful act, the Alarm Handler started beeping indicating that the dust particle|
counts for particles of diameter less than 0.5 micron had exceeded 5000 /cu. ft. Here's the
80 day trend of particles, temperature and humidity:
|Attachment 1: Untitled.png
||Thu Jun 26 01:08:22 2008
||rana||Configuration||General||Alarm Handler Revived|
|I have revived the Alarm Handler by turning it on on op540m and adjusting the levels of|
several of the alarming channels to not alarm (like laser power). The alarm levels are now
set to something reasonable and people should start actually paying attention to them.
I also removed the EO Shutter and Stacis alarm stuff since we don't use them.
To really get in and edit it, you have to close the Alarm Handler and edit the file
in /cvs/cds/caltech/alh/. It allows you to add/subtract useful channels and put in
If the alarm handler beeps about something, don't just close it or silence it, Steve. Just
fix it somehow (either set the threshold better or find the real cause).
|Attachment 1: b.gif
||Wed Jun 25 18:03:21 2008
||Yoichi||Configuration||PSL||FSS Input Offset slider problem|
|While working on the PMC scanning, I noticed that the FSS input offset slider is doing nothing.|
I traced the signal flow and checked the cables/boards.
The slider changes the output voltage from a VMIVME4116 DAC in the PSL rack. This output voltage is confirmed to be correct at the FLKM64 connector. The signal is connected to the FSS servo interface box (D040423) trough a ribbon cable. However, the output from the interface box is always -27V regardless of the slider position.
Therefore, either the interface box (D040423) or the ribbon cable has a problem.
I will debug the interface box using an extension card when no one is working on the interferometer.
||Wed Jun 25 13:56:56 2008
||John||Summary||Locking||Tuesday night locking|
Worked to try and reduce the CARM offset using the dc arm transmissions before changing to SPOB DC. This proved somewhat unsuccessful, the offset couldn't be reduced to more than five (arms storing 5x more power than single arm cavity lock).
||Wed Jun 25 13:38:22 2008
||Koji||Update||General||Abs. Len. Meas. ~ Placement of the 700mW NPRO on the AP table|
|This morning I have put the 700mW NPRO on the AP table for the abs length measurement.|
The RF amplifier was moved (the cables were not changed). I cleaned up some cable arrangements. I was keen not to disturb any of the other optical path. Even so, please let me know if any suspicious behaviour is found on the AP table.
|Attachment 1: NPRO700mW_placement.jpg
||Wed Jun 25 12:25:28 2008
||Eric||Summary||Cameras||2D Gaussian Fitting Code|
|I initially wrote a script in MATLAB that takes pictures of the laser beam's profile and fits them to a two dimensional gaussian in order to determine the position and width of the beam. This code is now (mostly) ported to C so that it can be imbedded in the camera software package that Joe is writing. The fitting works fairly well for pictures with the beam directly incident on the camera, and less well for pictures of scatter off the end mirrors of the arms, since scatter from defects in the mirror have intensities much greater than the intensity of the beam's gaussian profile.|
The next steps are to finish up porting the fitting code to C, and then modify it so it can better handle the images off the end mirror. Some thoughts on how to do this are to use a fourier transform and a low pass filter, or to simply use a center-of-mass calculation (with the defect peaks reduced in intensity), since position is more important than beam width in this calculation. The eventual goal is to include the edge of the optic in the picture and use the fit of the beam position in comparison to the optic's position to find the beam's location on the mirror.
||Wed Jun 25 11:36:14 2008
||Max Jones||Update||Computer Scripts / Programs||First Week Update|
|For the first week I have been modifying the noise budget script in caltech/NB to run with 40 m parameters and data. As per Rana's instructions, I have tried to run the script with only seismic and Darm sources. This involves identifying and changing channel names and altering paramter files (such as NB/ReferenceData/C1IFOparams.m). To supply the parameter files, I have copied the H1 files with (as yet only) slight modification. The channel name changes have been made to mirror the sites for the most part. Two figures are attached which show the current noise budget. The Day plot was taken 6/23/08 at ~10:30 am. The night plot was taken 6/22/08 at ~11:00 pm . Note that the SRD curve is for the sites and not for the 40 m (I hope to change that soon). Also in one of the plots the DARM noise signal is visible. Obviously this needs work. A list of current concerns is |
1) I am using a seismic transfer function made by previous SURF student Ryan Kinney to operate with channels of the form C1:PEM_ACC-ETMY_Y (should I be using C1:DMF-IX_ACCY?) and the channels I am currently using are the acceleraometers for the mode cleaner with names of the form C1:PEM_ACC-MC1_X. Rana said that he thinks these may be the same but I need to be sure.
2) We don't have a DARM_CTRL channel but the code requires it, currently I am using DARM_ERR as a substitute which is probably partly responsible for the obvious error in DARM noise.
Any suggestions are appreciated. Max.
|Attachment 1: C1_NoiseBudgetPlot_Day.eps
|Attachment 2: C1_NoiseBudgetPlot_Night.eps
||Wed Jun 25 11:01:45 2008
||Masha||Update||Auxiliary locking||fiber stabilization|
|For the first week, I have been learning about fiber noise cancellation, auxiliary locking techniques, and other relevant helpful topics in more detail. I am now working on a setup (more detail in previous entry) to measure phase noise introduced by 25m(?) fiber, and then will proceed to try to cancel the noise.|
||Wed Jun 25 09:46:45 2008
||Sharon||Update|| ||Adaptive Filters|
|I have been learning about different methods for applying adaptive filters to improve the Mode Cleaner lock in specific, and other LIGO systems in general.|
Finding the exact number of coeffs we would like to apply for our FIR adaptive filter is very important to the efficiency of the filter. Getting this number higher might improve the accuracy of the filter, but costs time we do not have. Another important number to find is the step size. The step size is the variable that controls how far back we want to look into our data for finding the new coeffs. To understand more about the step size it is necessary to learn about the standard deviation of our input and output signals. By getting the step size too big, we are considering long term behavior, but might be missing out on a short term one.
In the near future I will be learning about the meanings of these variables and their contribution to the over all accuracy of our filters.
Results will be posted.
||Wed Jun 25 01:30:19 2008
||John||Summary||IOO||Frequency noise after the MC|
|I made some (very) rough estimates of the contribution made to the noise after the mode cleaner by three sources.|
Seismic noise - how much of the signal is due to the mode cleaner compenstaing for seismic disturbance of CARM.
Actuator noise - coil drivers and DAC noise.
MC_F - estimate of MC_F suppressed by the loop gain.
|Attachment 1: MC2noise080623.png
||Wed Jun 25 00:35:40 2008
||Koji||Summary||General||Optical Layout on the AP table|
|I have visited the AP table in order to investigate where we are going to put the optical setup for the abs. length meas. |
I have attached the PNG and PDF files to share the optical layout. It is not complete. Any comments or corrections are welcome.
|Attachment 1: optical_layout_ap_table.png
|Attachment 2: optical_layout_ap_table.pdf
||Tue Jun 24 22:43:23 2008
|Attachment 1: Screenshot.png
||Tue Jun 24 22:31:10 2008
||Masha||Update||Auxiliary locking||my first step in fiber stabilization|
|There is a new 1W INNOLIGHT NPRO laser at the Symmetric Port.|
Set up an interferometer to measure difference in phase noise introduced by a fiber. Works as expected without the fiber! (balanced intensity, out of phase noise in the two outputs).
||Tue Jun 24 17:12:10 2008
||josephb, Eric||Configuration||Cameras||GC750 setup, 1X4 Hub connected, ETMX images|
|The GC750 camera has been setup to look at ETMX. In addition, the new 1X4 rack mounted switch (18.104.22.168) has been connected via new cat6 cable to the control room hub (22.214.171.124?), thanks to Eric. The camera is now plugged into 1X4 rack switch and now has a gigabit connection to the control room computers as well as Mafalda (126.96.36.199).|
By using ssh -X mafalda or ssh -X 188.8.131.52, then typing:
A viewer will be brought up. By clicking on the 3rd icon from the left (looks like an eye) will bring up a live view.
Closing the view, and then cd ../../40mCode, and then running ./Snap --help will tell you how to use a simple code for taking .tiff images as well as setting things such as exposure length and size of image (in pixels) to send.
When the interferometer was set to an X-arm only configuration, we took two series of 200 images each, with two different exposure lengths.
Attached are three pdf images. The first is just a black and white single image, the second is an average of 100 images, and the third is the standard deviation of the 100 images.
|Attachment 1: GC750_ETMX_E30000_single.pdf
|Attachment 2: GC750_ETMX_E30000_avg.pdf
|Attachment 3: GC750_ETMX_E30000_std.pdf
||Tue Jun 24 15:15:09 2008
|Rob, Rana, John|
In the past week or so we've been working on reducing the CARM offset using a DC signal (SPOB DC).
We were able to get up to arm powers of around 30 (where a single arm cavity lock is a power of 1)
before instability set in and we would lose lock for, as yet, unknown reasons.
In recent nights locking efforts have taken a few backward steps.
Since last Thursday engaging the AO path has proved troublesome, i.e. engaging it would instantly
cause loss of lock. This seems to be related to problems with the mode cleaner servo. For the past
few nights it has been behaving strangely and could not be operated with the usual super boost stages.
Last night the situation was improved. MC boost stages could be used and the AO path engaged. The
cause of this problem and its spontaneous resolution are not understood.
Last night we were unable to switch CARM to SPOB DC. I've attached a spectrum of the MC2 length signal.
This path is being used for CARM and so gives an indication of the frequency noise after the mode
cleaner. At the moment the plot is calibrated in units of Rana's gut feeling. We already tested to see if
any of the excess noise was introduced by the WFS. No evidence was found. We'll try to make a useful
calibration soon and see if our problems are related to excess frequency noise.
Another realisation from last night was the effect of arm detuning on the analogue CARM path. When CARM is detuned
the coupled cavity pole removes an extra 90 degrees of phase. The digital path has the `moving zero' to compensate
for this. The analogue path has no such compensation and can therefore become unstable at moderate detunings.
We propose trying to reduce the CARM offset further before engaging the analogue path. This will give higher
gain and move the UGF to a region of increased phase margin.
|Attachment 1: mcl080623.png
||Tue Jun 24 10:24:43 2008
||Koji||Update||General||Abs. Len. Meas. ~ Cavity Swing Measurement (2)|
|At the entry 555, Alberto reported the results of the cavity length measurement using cavity sweeping.|
As expected, each result inevitably has an ambiguity depending on which resonance do we take as an upper sideband.
In order to exclude this ambiguity Steve and Koji performed a primitive non-optical measurement using a tape and photos:
This morning Steve and Koji did tape measurements to know the lengths between the ITM/ETM chambers.
Yesterday, Koji took photos of the optical tables in vacuum to know the actual positions of the suspensions.
The results are shown in the figures attached. From those non-optical measurements the lengths of the X/Y arm are known to be 38.48+-0.03 / 38.67+-/0.03 [m].
Then, we could exclude the shorter lengths of the values in the entry 555. i.e. The Y arm is longer than the X arm about 0.2 m.
These approximate lengths will be used in the further precise measurements which use precise scans of the FSR frequencies.
|Attachment 1: armlength.png
|Attachment 2: armlength2.png
||Mon Jun 23 21:51:19 2008
||Alberto||Update||General||Arm Cavity Length Measurement|
|We measured the arm cavity lengths sweeping the ETM mirror position and looking at the reflected demodulated output. We excited the mirror by a sine wave of 0.2 Hz and amplitude of 30000 counts. From the time series of the occurrences of the resonances of the sidebands and of the carrier we evaluated the free spectral range of the cavities and thus the lengths. The details of the procedure are explained in the attached document. As discussed in it, for each cavity we obtain two possible values of the length depending on which of the sideband resonances is that corresponding to the upper sideband and which corresponds to the lower one instead. The numbers are:|
Lx=(38.30 +/- 0.08)m / (38.45 +/- 0.08)m
Ly=(38.16 +/- 0.08)m / (38.70 +/- 0.08)m
Since the difference between the two possibilities is quite large, we should be able to decide which one is correct by somehow measuring directly the cavity length. We want to try it tomorrow by a tape meter.
Alberto and Koji
|Attachment 1: 40mLengthMeasure.pdf
||Mon Jun 23 19:48:28 2008
||rana,alberto||Summary||IOO||StochMon trends (80 days)|
|Here's a StochMon plot showing the RFAM after the MC. Remember that in these units, 2V means no RFAM|
and 0 V means lots of RFAM. Alberto says "the calibration is in Tiramisu". So there you go.
|Attachment 1: e.png
||Mon Jun 23 19:33:01 2008
||rana, jenne||Update||IOO||MC_F Noise check|
|We looked at the MC_F spectrum because Rob and Yoichi said that it had gone 'all crazy'. It|
seemed fine as we looked at it (even with only one boost stage on) so we looked for things
that might be marginal and make it go nuts.
At the error point (Q mon on the demod board and TEST IN1) of the MC Servo board we saw the
old 3.7 MHz signal (comes from the 33 MHz RFAM getting demodulated by the 29.5 MHz MC LO)
and thought that this might cause some worries. So we installed Jenne's passive elliptic
low pass which has a 3.7 MHz zero.
This wiped out the 3.7 MHz noise but we were not able to re-create the extra frequency noise
so its unlikely to have fixed the main problem. However, we leave it in because its good. If
there is a need to revert it, we have left hanging on the side of the rack the old cable which
was a SMA->TNC making a direct, unfiltered connection between the MC Demod board and the MC
More before and after results from Jenne tomorrow, but for now here is a calibrated MC_F spectrum
using the new MC_F-Reference.xml template file.
We also noticed that we could make some small effects on the MCF spec by adjusting the PMC gain so
there's probably more hay to be made there using a lead brick and a gain slider. More in Jenne's
|Attachment 1: mcf.png
||Mon Jun 23 15:22:04 2008
||rana||Bureaucracy||SAFETY||Laser Safety Walkthrough today|
|Attachment 1: Walkthrough08.jpg
||Sun Jun 22 21:38:49 2008
Now that we're getting back into locking, it's nice to have a stable alignment of the interferometer.
Thus, after you're done with your experiment using subsets of the interferometer (such as a single arm),
please use the IFO_CONFIGURE screen, and click "Restore last Auto-Alignment" in the yellow "Full IFO" section.
If you don't know what this means/how to do this, you shouldn't be using the interferometer on your own.
||Fri Jun 20 17:42:48 2008
||steve||Update||PSL||SS trap scattering compared to black glass trap|
|Circular SS304 trap was compared to wedged black glass trap.|
The measurement set up of entry 529 was changed to define polarization.
CrystaLaser was remounted in horizontal position and half wave plate was placed after it.
These measurements were done in horizontal polarization.
atm1: the cSSt and wBGt was moved horizontally, ~90 degrees of the incident beam
atm2: traps were rotated around the incident beam, ~20 degrees each direction
atm3: set up
atm4: top view of traps
atm5: side view of trap
|Attachment 1: cSSt_1.png
|Attachment 2: cSSt_2.png
|Attachment 3: scatset_61908.png
|Attachment 4: cSSt&wBGt.png
|Attachment 5: cSStbeam.png
||Fri Jun 20 08:30:27 2008
||stiv||Update||Photos||40m summer line up 2008|
|atm1: John, Alberto, Yoichi, Koji, Masha, and Sharon |
atm2: surf students Max of CIT, Sharon of MIT, Masha of Harvard, Eric of CIT not shown
|Attachment 1: P1020559.png
|Attachment 2: P1020560.png
||Fri Jun 20 02:20:33 2008
||Yoichi||Update|| ||PMC transmittance degradation|
|The PMC transmitted light power has been degrading constantly for last two weeks (see the attachment 1).|
I went down to 2.55V.
The output of the MOPA is constant during this period. More strangely, the reflected power from the PMC is also constant.
One possible explanation is the contamination of the PMC mirrors. But I don't know why it started two weeks ago.
I tweaked the alignment of PMC and was able to recover the transmitted power to above 2.7V (attachment 2).
I will keep eye on this issue.
|Attachment 1: pmc_trans_long_trend.pdf
|Attachment 2: pmc_trans_improvement.pdf
||Fri Jun 20 01:38:55 2008
||rana||Update||PEM||20 day Weather|
|Yoichi showed me that its possible to make PNG images from PS using GS:|
gs -sDEVICE=png16m -sOutputFile=foo.png bar.ps
|Attachment 1: test.png
||Thu Jun 19 20:22:03 2008
||rana||Update||General||FE Computer Status|
|I called Rolf (@LLO) who called Alex (@MIT) who suggested that we power cycle every crate |
with an RFM connection as we did before (twice in the past year).
Rob and I followed Yoichi around the lab as he turned off and on everything. There
was no special order; he started at the Y-end and worked his way into the corner and
finishing at the X-End. Along the way we also reset the 2 RFM switches around fb0.
This cured the EPICS problem; the FEs could now boot and received the EPICS data.
However, there are still some residual channel hopping-ish issues which Rob and Yoichi are
now working on.
||Thu Jun 19 15:52:06 2008
||Alberto||Configuration||Computers||Measure of the current absorbed by the new Megatron Computer|
|Together with Rich Abbot, sam Abbot and I measured the current absorbed by the new Megatron computer that we installed yesterday in the 1Y3 rack. The computer alone absorbs 8.1A at the startup and then goes down to 5.9A at regime. The rest of the rack took 5.2A without the computer so the all rack needs 13.3 at the startup and the 11.1A.|
We also measured the current for the 1Y6 rack where an other similar Sun machine has been installed as temporary frame builder and we get 6.5A.
Alberto, Rich and Sam Abbot
||Wed Jun 18 18:50:09 2008
||rana||Update||Computers||It can only be attributable to human error. (HAL - 2001)|
|There has been another one of "those" events and all of the front end machines are down.|
We poked around and Rob determined that the FEs can't get the EPICS data from EPICS. The
dcuepics machine is hooked up and running and all of the epics binaries are running. We also
tried resetting its RFM switch as well as power cycling the box using the "poweroff" command.
Not a sausage.
Rob points out that although the Signal Detect lights are on on the cards, the 'Own Data' light
is not on on the dcuepics' card although it is on for some of the cards on the other boxes.
We have placed messages with the Russian. If anyone sees him, don't let him go without fixing things.
Also, make sure to follow him around with notepad and possibly a camera to record what it is that
he does. If he's muttering, maybe try to use a sensitive hidden sound recorder.
||Wed Jun 18 18:32:09 2008
||Max Jones||Update||Computer Scripts / Programs||NB Update|
|I am reconfiguring the the noisebudget code currently in use at the sights. To that end, I have done the following things (in addition to the elog I posted earlier)|
In get_dtt_dataset.m - I added C1 specific cases for DARM_CTRL, SEIS, and ITMTRX changing the specific channels to make those in use at caltech
In LocalizeSite.m - I changed the NDS_PATH to match caltechs. I left NDS_HOST untouched.
Since I am trying to get SEIS and DARM to work initially I added C1 specific cases to both of these.
Better documentation may be found in /users/mjones/DailyProgressReport/06_18_08. Suggestions are appreciated. Max.
||Wed Jun 18 18:26:19 2008
||Yoichi||Update||PSL||Finding the optimal operation temperature for the NPRO by the slow act scan|
|Being suspicious of the temperature stabilization of the NPRO crystal, I ran the slow scan script written by Rana to find the suitable operation temperature.|
The procedure is the same as the one explained in the entry below:
The attached plots show the results. By looking at C1:PSL-126MOPA_126MON, I set the slow slider voltage to 0.
This time, it looks like the temperature control of the NPRO crystal is working fine.
Obviously, PMC picks up many higher order modes. I will try to mode match/align the PMC later.
|Attachment 1: FSS-slow-scan.pdf
||Wed Jun 18 18:20:10 2008
||Yoichi||Update||PSL||Investigation on the NPRO temperature stabilization glitches|
|As Rob pointed out in http://dziban.ligo.caltech.edu:40/40m/537 the MOPA NPRO has been showing some glitchiness in the LTEC loop.|
Following Rana's suggestion, Steve and I opened the MOPA and directed a heat gun for a minute to the NPRO hoping that we can see something in the LTEC loop.
The first attachment shows the behavior of LTMP and LTECH along with DTMP and DTECH at the time of the heat gun attack.
T=0 is the time when Steve directed the heat gun to the NPRO. There is no response neither in LTMP nor LTECH.
DTMP and DTECH look like responding.
Around the center, there is a dip in LTMP. This might be caused by removing the heat gun. But we are not sure. This kind of small glitches can be found in LTMP everywhere (see the attachment 2).
It looks like the LTMP sensor is not working, or the LTECH loop is actually working but the LTECH reading is broken.
However, the scan of the slow actuator (temperature) shows the LTECH loop is actually working. So it is a bit confusing.
More investigation is necessary.
See the next entry by me.
|Attachment 1: LTEC-loop-HeatGun-Response.pdf
|Attachment 2: LTMP-glitches.pdf
||Wed Jun 18 16:37:54 2008
||steve,rana||Update||SAFETY||CO2 test in the east arm|
|The CO2 laser and table are in the east arm for characterization of the mechanics. We|
will not be operating it until we have an SOP (which is being written). No worries.
|Attachment 1: co2.png
||Wed Jun 18 16:07:57 2008
||rob||Summary||Computers||RFM network down|
The RFM network tripped off around noon today. It's still down. The problem appears to be with the EPICS interface (c1dcuepics). Trying to restart one of the end stations yields the error: No response from EPICS.
Possible causes include (but not limited to): busted RFM card on c1dcuepics, busted PMC bus on c1dcuepics, busted fiber from c1dcuepics to the RFM switch. We need Alex.
||Wed Jun 18 00:19:29 2008
|15 day trend of MOPA channels. The NPRO temperature fluctations are real, and causing the PMC to consistently run up against its rails. The cause of the temperature fluctations is unknown. This, combined with the MZ glitches and Miller kicking off DC power supplies is making locking rather tetchy tonight. Hopefully Yoichi will find the problem with the laser and fix it by tomorrow night.|
|Attachment 1: MOPAtrend.png
||Tue Jun 17 22:00:53 2008
||John||HowTo||PSL||Problems turning MZ servo on/off|
|We were unable to toggle the MZ servo on/off (Blank/Normal) from MEDM. Pushing on the Xycom board and cables changed the fault from constant to intermittent. At least one lock loss has been caused by a MZ glitch.|
||Mon Jun 16 18:26:01 2008
||Max Jones||Update||Computer Scripts / Programs||Noise Budget Changes|
|In the directory cvs/cds/caltech/NB the following changes were made:|
I created temporary files in ReferenceData for the C1 by copying and renaming the corresponding H1 files.
In getmultichan.m I added a C1 case.
In NoiseBudget.m I added a C1 case with modified sources array to include only DARM and Seismic
I appreciate and suggestions. Max.
||Fri Jun 13 11:17:25 2008
||Yoichi||Update||PSL||PMC transmittance at high power|
|We received a new cable for the Scientech calorimeter. So I measured the transmittance of the PMC at higher power.|
Input power = 2.298W
Output power = 1.364W
Transmittance = 59%
The input power to the PMC was measured between the two mode matching lenses by the calorimeter.
2.298W looks a bit too low. Actually, the calibrated monitor PD on the MEDM screen shows about 3W output from MOPA.
So we (me and Steve) measured the power right after the PBS after the periscope from MOPA with the HWP set to maximize the transmission of the PBS.
It was 2.77W. According to Steve's previous measurement, the first mirror of the periscope transmits about 200mW of the incoming light to the monitor PD. So the actual output of the MOPA is about 2.97W, which is consistent with the monitor PD reading.
The aperture of the EOM for the PMC control is glowing a lot. We suspect this is the main cause of the loss (from 2.77W to 2.298W).
We may want to re-align the EOM.
The output light from the PMC was picked off by a glass slide. The reflectance of the glass slide was measured first at a lower power (input 98mW, reflected power 1.58mW). Assuming that the reflectance is the same for the higher power, I turned up the input power to the PMC. This time, the picked off power was 22.45mW. This means the actual output power is 98/1.58*22.45=1364mW. The glass slide was kept at the same angle through out the measurement.
The measurement of the output power was done by the Ophir power meter. So calibration difference between the Ophir and the calorimeter may introduce some error.
||Thu Jun 12 15:55:15 2008
|Rob: Awesome figure. As you can imagine, I have lots of questions, and hope that you will consider this figure to be the beginning, leading to ever-more detailed versions. But for now, I just want to ask whether you understand *what* is twitchy, and what the twitchiness does to prevent you from taking this further?|
I definitely don't understand what's twitchy, but I have suspicions. Tonight we'll try to start by revisiting the other loops (the non-CARM loops) and see how they're dealing with the changing power levels. It may be that the DARM loop is going unstable due to gain variations (due to either increasing power or to rotation of demod phase) or it could be the PODD (or SPOB) saturating with increased power in the recycling cavity. I just hope the glitchiness doesn't have a digital origin.
||Thu Jun 12 15:09:33 2008
|Rob: Awesome figure. As you can imagine, I have lots of questions, and hope that you will consider this figure to be the beginning, leading to ever-more detailed versions. But for now, I just want to ask whether you understand *what* is twitchy, and what the twitchiness does to prevent you from taking this further?|
||Thu Jun 12 01:51:23 2008
We've been working (nights) on getting the IFO locked this week. There's been fairly steady incremental progress each night, and tonight we managed to control CARM(MCL) using PO-DC, with the CARM(AO) path also on PO-DC. In the past, reaching this state has usually meant we're home free, as we could just crank the gain on the common mode servo and merrily reduce the CARM offset. Tonight, however, this state has been very twitchy, and efforts to ramp up the gain have been unsuccessful.
I've attached a diagram which I hope makes clear where we are in the stages of lock acquisition.
|Attachment 1: lock_control_sequence.png
||Wed Jun 11 15:30:55 2008
|The trial use GC1280 has arrived. This is a higher resolution CMOS camera (similar to the GC750). Other than higher resolution, it has a piece of glass covering and protecting the sensor as opposed to a plastic piece as used in the GC750. This may explain the reduced sensitivity to 1064nm light that the camera seems to exhibit. For example, the image averages presented here required a 60,000 microsecond exposure time, compared to 1000-3000 microseconds for similar images from the GC750. This is an inexact comparison, and the actual sensitivity difference will be determined once we have identical beams on both cameras.|
The attached pdfs (same image, different angles of view) are from 200 averaged images looking at 1064nm laser light scattering from a piece of paper. The important thing to note is there doesn't seem to be any definite structure, as was seen in the GC750 scatter images.
One possibility is that too much power is reaching the CMOS detector, penetrating, and then reflecting back to the back side of the detector. Lower power and higher exposure times may avoid this problem, and the glass of the GC1280 is simply cutting down on the amount passing through.
This theory will be tested either this evening or tomorrow morning, by reducing the power on the GC750 to the point at which it needs to be exposed for 60,000 microseconds to get a decent image.
The other possibility is that the GC750 was damaged at some point by too much incident power, although its unclear what kind of failure mode would generate the images we have seen recently from the GC750.
|Attachment 1: GC1280_60000E_scatter_2d.pdf
|Attachment 2: GC1280_60000E_scatter_3d.pdf
||Wed Jun 11 11:45:25 2008
||steve||Update||PSL||ss trap works|
|The trap works well at 3 W level. No back reflected beam coming out of the trap on low power|
sensing card level. The back scattering was not measured. The trap is insensitive to small pointing variations.
The SS surface did not show any visible degradation after 16 hrs of 3w exposure at elliptical beam size 4x8 mm
It is ready to be placed into the 35 W beam.
|Attachment 1: P1020534.png
|Attachment 2: P1020533.png
||Tue Jun 10 08:37:18 2008
||steve||Update||PSL||beam trap is being tested|
|High power beam trap is being tested just west of FSS area on psl enclosure.|
When the pmc is operating at low power that means that the rest of the 3W is going into the
circular SS trap.
Please beware of the high power beam trap test
|Attachment 1: trapss3w.png
||Mon Jun 9 17:57:59 2008
||Yoichi||Configuration||PSL||PMC input power backed to the original|
|I rotated back the HWP before the PBS to restore the input laser power to the PMC.|
Now the reading of PSL-PMC_PMCTRANSPD is 2.7.
||Mon Jun 9 17:32:14 2008
|I checked the current PMC transmissivity at a low power.|
The input laser power to the PMC was reduced to 75mW by rotating the HWP in front of the PBS.
In this configuration, the output power from the PMC was 50mW. So the transmittance is about 66%.
The reading of C1:PSL-PMC_PMCTRANSPD is now 0.1 whereas it was 2.7 before turning the power down.
I will check the transmittance at a higher power when I get the cable for the 35W calorie meter, which is missing now.