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ID Date Author Type Categoryup Subject
  36   Wed Oct 31 08:38:35 2007 ranaProblem FixedIOOMC autolocker
The MC was having some trouble staying locked yesterday. I tracked this down to some steps in the last
half of the mcup script; not sure exactly which ones.

It was doing something that made the FAST of the PSL go to a rail too fast for the SLOW to fix.
So, I broke the script in half so that the autolocker only runs the first part. We'll need to
fix this before any CM locking can occur.

We also need someone to take a look at the FSS Autolocker; its ill.
  39   Wed Oct 31 15:02:59 2007 tobinRoutineIOOMode Cleaner Mode Tracking
I processed the heterodyned mode cleaner data yesterday, tracking the three 28 kHz modes corresponding to MC1, MC2, and MC3. Unfortuntately the effect of our MC power chopping is totally swamped by ambient temperature changes. Attached are two plots, one with the tracked mode frequencies, and the other containing dataviewer trends with the MC transmitted power and the room temperature. Additionally, the matlab scripts are attached in a zip file.
Attachment 1: mode-track.pdf
Attachment 2: trends.pdf
Attachment 3: mcmodetrack.zip
  40   Wed Oct 31 15:22:59 2007 robConfigurationIOOMode Cleaner transfer function
I measured the transfer function of the input mode cleaner using a PDA255 and the ISS. First I put the PD in front of the ISS out-of-loop monitor diode and used an SR785 to measure the swept sine transfer function from the Analog IN port of the ISS to the intensity at the PD. Then I moved the PD to detect the light leaking out from behind MC2, using ND filters to get the same DC voltage, and measured the same transfer function. Dividing these two transfer functions should take out the response of the ISS and the PD, and leave just the transfer function of the MC. A plot of the data, along with a single-pole fit, are attached.

The fit is pretty good for a single pole at 3.79 kHz. There's a little wiggle around 9kHz due to ISS weirdness (as Tobin has not been giving it the attention it requires), but this shouldn't affect this result too much. Using the known MC length of 27.0955m, and assuming that MC1 and MC3 have a power transmissivity of 2000ppm and MC2 is perfectly reflecting, the total round trip loss should be about 300ppm. The fitted finesse is 1460.
Attachment 1: MCtf.pdf
  45   Thu Nov 1 11:45:30 2007 tobinConfigurationIOOMode cleaner drag-wiping
Andrey, Bob, David, John Miller, Rana, Rob, Steve, Tobin

Yesterday we vented the vacuum enclosure and opened up the chamber containing MC1 & MC3 by removing the access connector between that chamber and the OMC chamber. Rana marked MC1's location with dogs and then slid the suspension horizontally to the table edge for easy drag-wiping access. The optic was thoroughly hosed-down with the dionizer, in part in an effort to remove dust from the cage and the top of the optic. Drag-wiping commenced with Rob squirting (using the 50 microliter syringe) and Tobin dragging (using half-sheets of Kodak lens tissue). We drag-wiped the optic many (~10) times, concentrating on the center but also chasing around various particles and a smudge on the periphery. There remains one tiny speck at about the 7:30 position, outside of the resonant spot area, that we could not dislodge with three wipes.

Today we drag-wiped MC3. First we slid MC1 back and then slid MC3 out to the edge of the table. We disconnected the OSEM cables in the process for accessibility, and MC1 is perched at an angle, resting on a dog. We did not blow MC3 with the deonizer, not wanting to blow particles from MC3 to the already-cleaned MC1. We drag-wiped MC3 only three times, all downward drags through the optic center, with Steve squirting and Tobin dragging. Some particles are still visible around the periphery, and there appears to be a small fiber lodged near the optic center on the reverse face.

Andrey and Steve have opened up MC2 in preparation for drag-wiping that optic after lunch.
  61   Sun Nov 4 23:55:24 2007 ranaUpdateIOOFriday's In-Vac work
On Friday morning when closing up we noticed that we could not get the MC to flash any modes.
We tracked this down to a misalignment of MC3. Rob went in and noticed that the stops were
still touching. Even after backing those off the beam from MC3 was hitting the east edge of
the MC tube within 12" of MC3.

This implied a misalignment of MC of ~5 mrad which is quite
large. At the end our best guess is that either I didn't put the indicator blocks in the
right place or that the MC3 tower was not slid all the way back into place. Since there
is such a strong stickiness between the table and the base of the tower its easy to
imagine the tower was misplaced.

So we looked at the beam on MC2 and twisted the MC3 tower. This got the beam back onto the
MC2 cage and required ~1/3 if the MC3 bias range to get the beam onto the center. We used
a good technique of finding that accurately: put an IR card in front of MC2 and then look
in from the south viewport of the MC2 chamber to eyeball the spot relative to the OSEMs.

Hitting MC2 in the middle instantly got us multiple round trips of the beam so we decided
to close up. First thing Monday we will put on the MC1/MC3 access connector and then
pump down.

Its possible that the MC length has changed by ~1-2 mm. So we should remeasure the length
and see if we need to reset frequencies and rephase stuff.
  62   Mon Nov 5 07:29:35 2007 ranaUpdateIOOFriday's In-Vac work
Liyuan recently did some of his pencil beam scatterometer measurements measuring not the
BRDF but instead the total integrated power radiated from each surface point
of some of the spare small optics (e.g. MMT, MC1, etc.).

The results are here on the iLIGO Wiki.

So some of our loss might just be part of the coating.
  67   Tue Nov 6 10:42:01 2007 robConfigurationIOOmode cleaner locked
Increased the power exiting the PSL by turning the half-wave plate after the MOPA, opened the PSL shutter, and aligned the mode cleaner to the input beam. It wasn't that hard to find the beam with the aperture open all the way on the MC2 camera. The transmitted power is now 2.9 arbitrary units, while the input power is 1.2 arbitrary units. Not sure yet if that's an increase or decrease in efficiency, since no one posted numbers before the vent. Also turned on the input-steering PZTs and saw a REFL beam on the camera.
  68   Tue Nov 6 14:51:03 2007 tobin, robUpdateIOOMode cleaner length
Using the Ward-Fricke variant* of the Sigg-Frolov method, we found the length of the mode cleaner to be 27.0934020183 meters, a difference of -2.7mm from Andrey, Keita, and Rana's measurement on August 30th.

The updated RF frequencies are:
3  fsr =  33 195 439 Hz
12 fsr = 132 781 756 Hz
15 fsr = 165 977 195 Hz
18 fsr = 199 172 634 Hz
* We did the usual scheme of connecting a 20mVpp, 2 kHz sinusoid into MC AO. Instead of scanning the RF frequency by turning the dial on the 166 MHz signal generator ("marconi"), we connected a DAC channel into its external modulation port (set to 5000 Hz/volt FM deviation). We then scanned the RF frequency from the control room, minimizing the height of the 2 kHz line in LSC-PD11. In principle one could write a little dither servo to lock onto the 15fsr, but in practice simply cursoring the slider bar around while watching a dtt display worked just fine.
  74   Wed Nov 7 00:51:33 2007 andrey, rob, tobinConfigurationIOOMC ringdowns
We completed several ringdown measurements this afternoon; Andrey is currently processing the data.
  75   Wed Nov 7 02:14:08 2007 AndreyBureaucracyIOOMore information about MC2 ringdown
As Tobin wrote two hours ago, we (Andrey, Tobin, Robert) made a series of ringdown measurements for MC2
in the spirit of the measurement described by Rana -> see
entry from Mon Oct 29 23:47:29 2007, rana, Other, IOO, MC Ringdowns.

I attach here some pictures that we saw on the screen of the scope, but I need to admit that I am not experienced enough to present a nice fit to these data, although I attach fits that I am able to do today.

I definitely learned a lot of new Matlab functions from Tobin - thanks to him!, but I need to learn two more things:

Firstly, I do not know how to delete "flat" region (regions before the ringdown starts) in Matlab ->
I needed to delete the entries for times before the ringdown ("negative times") by hand in the text-file, which is extremely non-elegant method;

Secondly, I tried to approximate the ringdown curve by a function ydata=a*exp(b*xdata) but I am not exactly sure if this equation of the fitting curve is a good fit or if a better equation can be used.

It seems, in this situation it is better for me to ask more experienced "comrades" on November 7th.

P.S. It seems I really like the type of message "Bureaucracy" - I put it for every message. As Alain noted, maybe that is because some things are very bureacratized in the former USSR / Russia. By the way, when I was young, November 7th was one of two most important holidays in the USSR - I liked that holiday because I really liked military parades on the red square. I attach a couple of pictures. November 7 is the anniversary of the Revolution of 1917.
Attachment 1: image-attempt_1.png
Attachment 2: image-attempt_2.png
Attachment 3: image-attempt_3.png
Attachment 4: image-attempt_4.png
Attachment 5: image-attempt_5.png
Attachment 6: Fit-1st_attempt.jpg
Attachment 7: Fit-5th_attempt.jpg
Attachment 8: 7_Nov_1941-parad-na-krasnoy-ploschadi.jpg
Attachment 9: parad1984-moskva.jpg
  78   Wed Nov 7 13:54:44 2007 robConfigurationIOOMode Cleaner transfer function
I performed the same procedure described here, and re-measured the transfer function of the mode cleaner to see the effect of the drag-wiping. The results are attached in a pdf. We don't seem to have done any damage, but the improvements are barely measurable.

pole frequency3.789kHz3.765kHz
loss per optic99ppm91ppm
Attachment 1: mctf.pdf
  80   Wed Nov 7 14:05:59 2007 tobinConfigurationIOOMC ringdown
Modeling the mode cleaner as a simple cavity with all losses lumped together, we expect the cavity power to be
attenuated by a factor (1-L) after each interval (2l/c)=1/fsr. Therefore we can get the cavity loss L
(including power lost through transmission) from the ringdown time constant tau as:

L = 1 - exp[ - 1/(tau * fsr) ]

From this we have to subtract the 2000 ppm transmission for each of MC1 and MC3, and divide by three to spread
the losses across the three optics.

I get 168 39 ppm loss per optic based on a very simple exponential fit to the tails (t>0) of four of Andrey's data files.

By comparison, I get 154 37 ppm from Rana's data files from before the vent.
  125   Tue Nov 27 15:47:17 2007 robConfigurationIOOMC loop
After the FSS running pretty quick, I checked the MC loop. I used TPA 1&2.

MC loop
UGF: 70kHz
Input Gain: 29dB
Boost Level: 2
phase: 40 deg
Attachment 1: MCsmall.jpg
  126   Tue Nov 27 16:18:58 2007 robConfigurationIOOMC loop
Reduced the common gain to 22dB in the mcup script, so that the WFS would not blow the lock. The above measure of the OLG was done without the mcWFS running, so may be a low estimate as compared to when the alignment is perfect.
  154   Sun Dec 2 21:02:12 2007 ranaConfigurationIOOMC SUS re-alignment
The spot on MC2 was not centered, so I put it back in the center:

  • Made sure MC trans was high with the WFS off.
  • Moved the Sliders on the MC Align screen until spot was centered (by eye)
  • Moved some more until power was maximized.
  • Unlock MC
  • Center spots on McWFS
  • Re-enable autolocker and McWFS loops.
  155   Sun Dec 2 21:07:39 2007 ranaConfigurationIOOMC SUS re-alignment
you asked for:   diff 2007/12/01,4:58:48 2007/12/03,4:58:48 utc 'MC.*COMM'
LIGO controls: differences, 2007 12/01 04:58:48 utc vs. 2007 12/03 04:58:48 utc
__Epics_Channel_Name______   __Description__________   __value1____     __value2____
C1:SUS-MC1_YAW_COMM                                    -0.273460        -0.503460
C1:SUS-MC2_PIT_COMM                                     3.624020         3.632020
C1:SUS-MC2_YAW_COMM                                    -0.936800        -1.038800
C1:SUS-MC3_YAW_COMM                                    -3.129000        -3.369000
  156   Sun Dec 2 21:13:16 2007 ranaConfigurationIOOMC SUS re-alignment
Attachment 1: e.png
  178   Fri Dec 7 00:02:26 2007 ranaSummaryIOOMC/FSS Frequency Noise
The FSS frequency noise is not very bad.

I compared the MC_F spectra between Hanford and the 40m using DTT and its 'User NDS' option.
After Sam, Jenne, and DavidM installed the new MC Servo some time ago, the MC_F spectrum here
has had some whitening before it goes into the DAQ (on board; same as LLO & LHO). The tuning
coefficient of the VCO is also basically the same between all PSLs since everyone has the same
chip in the VCO driver.

Therefore, at the frequencies where the MC gain is more than ~4, the MC_F signal calibration is
the same here as anywhere. Since its the servo control signal, its basically a measure of the
frequency noise incident on the MC -- its just what comes out of the FSS with the table noise on
top. At low frequencies (< 100 Hz) its a measure of the motion of the MC mirrors.

Above 200 Hz ours is the same as theirs; except for the enormous power line spikes. I think that's
either all on the light. But our acoustics are better and the noise above 1 kHz levels off at the
same flat floor (the phase noise of the VCO) as H1. The huge lump around 100 Hz is the MC2 DAC noise and
it goes down to the H1 levels when we flip on the dewhites. The giant excess from 5-50 Hz is just the fact
that our stacks don't do much until 20-30 Hz.

So we can stop blaming the FSS and move on with life as soon as Tobin gets the ISS back in shape.
Attachment 1: fly.pdf
  304   Sat Feb 9 13:05:48 2008 JohnSummaryIOOPMC camera/ HEPA
I replaced the Gig-E camera on the PMC trans beam. The PZT was close to railing and I wanted to adjust it. I just did a quick job, there is a little scattered light on the image. If Joe is finished with the Gig-E I'll take another look at it.

The HEPA in the PSL table was turned off for some reason. I turned it back on.
  307   Sun Feb 10 21:43:16 2008 robConfigurationIOOMC alignment tweaked

I adjusted the alignment of the free hanging mode cleaner to best transmit the PSL beam.
  357   Tue Mar 4 20:14:02 2008 ranaConfigurationIOOMC Alignment
The MC alignment was pretty far off. We were getting TEM01 mode locks only.
Rather than inspect what happened I just aligned the MC suspensions to get
the transmission higher. Now Matt should be able to lock the X arm and collect
adaptive filter data.
  361   Wed Mar 5 17:35:24 2008 ranaUpdateIOORFAM during MC lock
I used an ezcaservo command to adjust the offsets for Alberto's StochMon channels. They are all
at +2 V with no light
on the RFAM PD (MC unlocked).

Then I looked at 5 minutes of second trend around when the MC locks. Since Alberto has chosen
to use +2V to indicate zero RF and a negative gain, there is a large RF signal when the StochMon
channels approach zero

From the plot one can see that the RFAM for the 133 & 199 MHz channels is much worse than for the 33 and 166.
Its also clear that the turn on of the WFS (when the RFAMPD's DC light level goes up) makes the single demod
signals get better but the double demod get worse.
Attachment 1: rfam.pdf
  372   Wed Mar 12 23:05:44 2008 ranaUpdateIOOMC WFS
they are bad, somewhat

please fix
  437   Tue Apr 22 17:08:04 2008 CarynUpdateIOOno signal for C1:IOO-MC_L
C1:IOO-MC_L signal was at zero for the past few days
  439   Tue Apr 22 22:51:30 2008 ranaConfigurationIOOMcWFS Status
I've been working a little on the MC WFS in the last few days. I have made many
changes to the sensing matrix script and also to the MCWFSanalyze.m script.

The output matrix, as it was, was not bad at low frequencies but was making noise in
the ~1 Hz band. Turning the gain way down made it do good things at DC and not make
things work higher.

The output matrix generating script now works after Rob fixed the XYCOM issue. Not sure
what was up there. As Caryn mentioned the SUS2.ini channels were all zero after Andrey's
PEM power cycle a few days ago. Rob booted c1susvme to get the SUS1 channels back and
today we did c1susvme2 to get the IOO-MC_L et. al. back.

Even after doing the matrix inversion there is some bad stuff in the output matrix. I
checked that the sensing matrix measurement has good coherence and I measured and set the
MC WFS RF phases (they were off by ~20-30 deg.). Still no luck.

My best guess now is that the RG filters I've used for POS damping and the movement of the
beam on the MC mirror faces has made a POS<->YAW instability at low frequencies. My next
move is to revert to velocity damping and see if things get better. Should also try redoing
the A2L on the MC1-3.
  451   Fri Apr 25 20:53:02 2008 ranaConfigurationIOOMC WFS with more gain
Quick update: we found that the reason for the MC WFS instability was that the digital anti-whitening was one but not the analog whitening.

We turned off the digital filters and were able to increase the gain by a factor of ~30. It is left like this, but if it hampers IFO locking then best to just turn it back down to an overall gain of 0.1 or 0.05.
  454   Sun Apr 27 02:11:11 2008 ranaConfigurationIOOMC WFS Notes
As noted in the elog from Friday, the WFS has been bad ever since someone switched on the digital whitening filters (FM1 & FM2)
in the MC WFS I&Q filter banks.

On Friday evening, John, Alan, and I went to the rack and verified that although the drawing shows a hookup for the whitening
filters, there is actually no such thing and so we can't have the whitening. So the anti-whitening turns on two lag filters
(2 poles at 4 Hz) and without the hardware this makes the servos unstable by adding 90 deg of phase lag at 4 Hz.

There are still several problems in this system:
- AD797 is used after the mixer. This is an unreliable, noisy part. We need to change this out
  with some OP27s so that this becomes reliable and has a more reasonable noise figure.

- Hard wire the whitening filters ON. We never want these to be off. Then we can turn on the
  anti-whitening. This will give us a factor of 100 better noise without filtering.

- The AD602 on the front of the whitening board has a 100 Ohm internal impedance and the 
  resistor between the demod board and the AD602 is 909 Ohms. This results in dividing the
  signal by 10.

- The signal at the ADC is ~100 cts peak-peak. The full ADC range is, of course, 65000 cts. So
  we could use a lot more gain. The mean quadrant signals are also ~100 cts so we could easily
  up the analog DC gain by a factor of 30 on top of the whitening filter increase.

- The AD602 at the input and the AD620 on the output are both variable gain stages but because
  of our lack of control are set to ambiguous gain levels. We should set the AD602 on the input
  to its max gain of 30 dB. With the -20 dB from the x10 voltage division, this will give us
  an overall gain of 3 for the puny demod signals.

  455   Sun Apr 27 05:09:30 2008 ranaConfigurationIOOMC WFS Whitening turned on
I hardwired on the MC WFS whitening filters.

The MAX333A switches which choose between whitening and bypass on that board were in the bypass position
because the Xycom220 connections are not there. So the control switch gets +15V but there is no pull
down to set it to the whitened mode.

The least invasive (easiest) change I could do was to tie all of those inputs to ground. This pulls a few mA
through the pull-down resistors but is otherwise innocuous. All of these control lines come in on the A-row
of the P1 connector, so I was able to solder a single wire across all of them to ground them all.

The WFS2 board had a blown electrolytic capacitor on the -15 V line and so there was probably some extra noise
getting in that way. I couldn't find any extra SMD to replace it so I cut the legs off of a 22 uF polarized
tantalum and stuck it in there. Its even close to being the same color. I checked out the other caps, and they were all
close to 68 uF as spec'd. This one had luckily blown open and so didn't suck down the Sorensen and destroy everything.

Plugged everything back in switched the WFS servos back on. Looks good. Took before and after spectra.

In the plot:

GREEN: Open loop dark noise before changes
RED: Open loop bright (MC locked but MCWFS off)
BLUE: Closed loop, MC locked

BLACK: Dark noise after whitening
ORANGE:Closed loop after whitening

The cursor is at 16.25 Hz, the SOS bounce mode.

The I ran the new setMCWFSgains script which uses pzgain to set the UGFs of the 4 loops to 4.01 Hz.
We have in the past had problems with high WFS gains causing instabilities with the CM servo around 10-30 Hz. If this happens we should
just lower the gain by a factor of ~5.
Attachment 1: mcnoise.png
  489   Tue May 20 18:33:01 2008 Andrey, JohnConfigurationIOOMode Cleaner is locked again

It was noticed by Mr.Adhikari earlier today that the MC became unlocked at about 11AM.

There is no clear understanding what caused the problem.

Trying to restore the modecleaner locking, we noticed with John that the beam was not centered on the wavesensors (WFS1. WFS2 on the screen "C1IOO_LockMC.adl"). We decided to adjust the beam position moving slightly the bias sliders for pitch and yaw degrees of freedom for MC1.
This allowed to make the MC locked.

Old positions for the MC1 sliders: Pitch = 2.9934, Yaw = -0.6168;
New positions --------//---------: Pitch = 3.0604, Yaw = -0.7258.

At the same time, FSS for PSL is still showing the values in the range 0.720 - 0.750 which is lower than the usual values. The indicator for FSS value is yellow when it is below 0.750.
  496   Sun May 25 19:33:16 2008 ranaUpdateIOOMC Bad after Re-alignment
The MC pointing was off and the transmitted power was down after John and Andrey brought it back after the bootfest.

I tried getting it back on Friday but was unsuccessful. Today, after the Phoenix Landing, I got it back to someplace
reasonable, but it still seems to be far off. I will check with Rob before we recenter and of the QPDs.

I had to move all of the MC SUS and also align the beam using the IOO periscope. The attached PDF shows some trends
over the last 80 days. You can see that the drop in MC TRANS is about the same as the drop in PMC TRANS.
Attachment 1: e.pdf
Attachment 2: pmc.png
  503   Thu May 29 15:58:44 2008 JohnSummaryIOOMC realignment
I repeatedly adjusted the yaw of the upper mirror on the input periscope and re aligned the MC. With the PRM aligned I tried to optimise MC transmission and DC refl simultaneously. I subsequently centred the beams on WFS1/2. Attached is a 30 day trend of MC alignment and transmission.
  553   Mon Jun 23 19:33:01 2008 rana, jenneUpdateIOOMC_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
servo board.

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
  554   Mon Jun 23 19:48:28 2008 rana,albertoSummaryIOOStochMon 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
  562   Wed Jun 25 01:30:19 2008 JohnSummaryIOOFrequency 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
  594   Sun Jun 29 19:19:47 2008 ranaSummaryIOOTrends of the PSL/IOO Quads over 1000 days
Only IOO POS has been working for the past 2 years. I guess we should recommission the IOO ANG and REFL QPDs
Attachment 1: a.png
  596   Sun Jun 29 20:09:40 2008 JohnSummaryIOOmcup and mcdown indicators
I edited the mcup and mcdown scripts so that C1IFO_STATE shows when these scripts are running.

I also added indicators to the LockMC screen.
Attachment 1: mcscreen.png
Attachment 2: ifostate.png
  598   Mon Jun 30 01:49:06 2008 JohnUpdateIOOMC work
I'm in the process of aligning the mode cleaner/ input beam.

I turned off the WFS and cleared their histories, adjusted the input periscope and re-aligned the mode-cleaner accordingly.
I then unlocked the cavity and centred the beams on the WFS.

MC transmission is ~3.3 and the REFL beam looks a little better.

However, turning the WFS on now lowers the transmission. More thought tomorrow.

I'm leaving the MC locked with WFS off.
  600   Mon Jun 30 08:59:23 2008 steveUpdateIOOIOO-MC_DEMOD_LO is low
The alarm handler is beeping relentlessly: asking for help in high partical count and low demod signal
Attachment 1: demlo.jpg_____
  601   Mon Jun 30 09:46:15 2008 JohnUpdateIOOMC WFS
MC WFS are on. They seem to do some good during the day.
  626   Wed Jul 2 18:30:01 2008 JohnUpdateIOOQPD alignment
I aligned the beams on the following QPDs

Attachment 1: IOO080702.png
Attachment 2: MC080702.png
  694   Fri Jul 18 16:57:37 2008 JenneUpdateIOOCalibrated MC_F
I have calibrated MC_F. The conversion factor is 137.49 MHz/count.

The calibration data taken is attached, along with a calibrated power spectrum.

On the data plot, the x axis is volts from the C1:IOO-MC_FAST_MON channel, with the calibration between FAST_MON and MC_F = -788.18 volts/count.
The linear term of the fit line = -0.085MHz/volt. Error bars are +/- 1 in the last digit of what the spectrum analyzer gave me for frequency (+/- 0.01MHz).

The net conversion factor is then (-788.18)*(-0.085)*(2) = 137.49 MHz/count. The factor of 2 is because the light passes through the AOM twice.

On the power spectrum,
REF0 and REF1 = MC unlocked, HEPAs on, MC Refl gain = 22
REF2 and REF3 = MC locked, HEPAs on, MC Refl gain = 22
REF4 and REF5 = MC locked, HEPAs on, MC Refl gain = 19
REF6 and REF7 = MC locked, HEPAs off, MC Refl gain = 19
Attachment 1: MC_Fcalib.png
Attachment 2: 20080717MC_F-MC_I.pdf
  696   Fri Jul 18 17:12:35 2008 JenneUpdateIOOChecking out the MC Servo Board
[Jenne, Max]

One of the things that Rana thinks that might be causing my MC_F calibration to be off is that the MC Servo Board's filters don't match those on the schematics. Max and I pulled the MC servo board today to check resistor and capacitor values. Alberto needed the Mode Cleaner, so we put the board back before finishing checking values. We will probably pull the board again next week to finish checking the values.

I haven't checked to ensure that the MC still locks, because Yoichi is doing stuff on the PSL table, but I didn't change anything on the board, and hooked all the cables back where they were, so hopefully it's all okay.
  697   Fri Jul 18 19:15:15 2008 JenneUpdateIOOChecking out the MC Servo Board

[Jenne, Max]

I haven't checked to ensure that the MC still locks, because Yoichi is doing stuff on the PSL table, but I didn't change anything on the board, and hooked all the cables back where they were, so hopefully it's all okay.

I put the PMC back and the MC now locks.
  710   Mon Jul 21 19:55:16 2008 rana,jenneConfigurationIOONoise in MC_F
Jenne put the MC board on extender today - its still that way but everything is probably connected (check AO).

We measured the TFs of the DAQ section for MC_F because of how everything looked wrong in the plots Jenne
put in the log earlier. Everything we measured today seemed to jive with the schematic. We also looked up
the original traveler for this board which Betsy filled in years ago: it also is in spec for the DAQ filtering.

So then I looked at the power spectrum of the output signal to the VCO. It had lots of HFC (high frequency crap).
I adjusted the parameters of the FSS (common gain, fast gain, RF phase Astonished) and lowered the MC common gain. This
produced a global minimum in that 4D parameter space.

I think that basically, the FSS gain is too low even with the common gain slider maxed. Having the fast gain up
at 19 dB like I had left it was bad - even though it minimizes the PC control signal, it produces a lot of HFC
up around 100 kHz in MC_F. After John (finally) gets around to measuring the FSS loop we can figure out how to
better tune this. The MC gain then has to be tuned so as to best minimize the HFC given the new FSS gain; there's
basically no coupling from the MC gain to the FSS loop shape so its always best to tune the FSS first. Pleased

The RF phase of the FSS was a mystery - I have no idea why it should do anything and I have never heard of this
and I don't know why I tried it today. But...changing it by ~0.6-0.7 slider units reduced the HFC by another factor
of ~3. Somebody should put this slider into units of degrees.8-)

Here's a table of the changes. Please make these the new nominals:
you asked for:   diff 2008/07/21,13:00 2008/07/22,2:44:16 utc '.*FSS.*|.*MC.*'
LIGO controls: differences, 2008 07/21 13:00:00 utc vs. 2008 07/22 02:44:16 utc
__Epics_Channel_Name______   __Description__________   __value1____     __value2____
C1:IOO-MC_REFL_GAIN                                    22.000000        19.000000
C1:IOO-MC_REFL_OFFSET                                  0.818380         0.818100
C1:PSL-FSS_MGAIN                                       10.000000        30.000000
C1:PSL-FSS_PHCON                                       2.073170         1.413170

The attached plot shows the "SERVO" TNC output of the board; this is supposed to be the same as the voltage going to the
VCO box. So its V/Hz transfer function is flat above 40 Hz. Tomorrow Jenne will post more data and remove the extender

Since I only used an SR785, I only saw noise up to 100 kHz. Its key to use an RF spectrum analyzer when checking out
the FSS and the MC systems.
Attachment 1: SCRN0024.GIF
  752   Tue Jul 29 01:03:17 2008 robConfigurationIOOMC length measurement
rob, yoichi

We measured the length of the mode cleaner tonight, using a variant of the Sigg-Frolov method. We used c1omc DAC outputs to inject a signal (at 2023Hz) into the AO path of the mode cleaner and another at DC into the EXT MOD input of the 166MHz IFR2023A. We then moved an offset slider to change the 166MHz modulation frequency until we could not see the 2023Hz excitation in a single-bounce REFL166. This technique could actually be taken a step further if we were really cool--we could actually demodulate the signal at 2023Hz and look for a zero crossing rather than just a powerspec minimum. In any case, we set the frequency on the Marconi by looking at the frequency counter when the Marconi setting+EXT MOD input were correct, then changed the Marconi frequency to be within a couple of Hz of that reading after removing the EXT MOD input. We then did some arithmetic to set the other Marconis.

The new f2 frequency is:

New              OLD
165983145        165977195

  753   Tue Jul 29 09:12:43 2008 KojiConfigurationIOOMC length measurement
I found that the prev modulation freq had been determined with a same kind of measurement by Osamu, which also looked accurate.

(There is also a document by Dennis to note about this measurement
http://www.ligo.caltech.edu/docs/T/T020147-00.pdf )

So, it means that the round trip length of the MC shortened by 1mm in the 6 years.
New              OLD
27.0924          27.0934    [m]

rob, yoichi

We measured the length of the mode cleaner tonight, using a variant of the Sigg-Frolov method.
The new f2 frequency is:
New              OLD
165983145        165977195
  757   Tue Jul 29 18:15:36 2008 robUpdateIOOMC locked

I used the SUS DRIFT MON screen to return the MC suspensions to near their pre-quake values. This required fairly large steps in the angle biases. Once I returned to the printed values on the DRIFT screen (from 3/08), I could see HOM flashes in the MC. It was then pretty easy to get back to a good alignment and get the MC locked.
  768   Wed Jul 30 13:14:03 2008 KojiSummaryIOOHistory of the MC abs length
I was notified by Rob and Rana that there were many measurements of the MC abs length (i.e. modulation 
frequencies for the IFO.) between 2002 and now.

So, I dig the new and old e-logs and collected the measured values of the MC length, as shown below. 

I checked the presence of the vent for two big steps in the MC length. Each actually has a vent. 
The elog said that the tilt of the table was changed at the OMC installation in 2006 Oct.
It is told that the MC mirrors were moved a lot during the vent in 2007 Nov.

o The current modulation freq setting is the highest ever.
o Rob commented that the Marconi may drift in a long time.
o Apparently we need another measurement as we had the big earthquake.

My curiosity is now satified so far.

Local Time	3xFSR[MHz]	5xFSR[MHz]	MC round trip[m]	Measured by
2002/09/12	33.195400 	165.977000 	27.09343		Osamu
2002/10/16	33.194871 	165.974355 	27.09387		Osamu
2003/10/10	33.194929 	165.974645 	27.09382		Osamu
2004/12/14	33.194609 	165.973045 	27.09408		Osamu
2005/02/11	33.195123 	165.975615 	27.09366		Osamu
2005/02/14	33.195152 	165.975760 	27.09364		Osamu
2006/08/08	33.194700 	165.973500 	27.09401		Sam
2006/09/07	33.194490 	165.972450 	27.09418		Sam/Rana
2006/09/08	33.194550 	165.972750 	27.09413		Sam/Rana
----2006/10 VENT OMC installation	
2006/10/26	33.192985 	165.964925 	27.09541		Kirk/Sam
2006/10/27	33.192955 	165.964775 	27.09543		Kirk/Sam
2007/01/17	33.192833 	165.964165 	27.09553		Tobin/Kirk
2007/08/29	33.192120 	165.960600 	27.09611		Keita/Andrey/Rana
----2007/11 VENT Cleaning of the MC mirrors
2007/11/06	33.195439 	165.977195 	27.09340		Rob/Tobin
2008/07/29	33.196629 	165.983145 	27.09243		Rob/Yoichi
Attachment 1: MC_length.png
  770   Wed Jul 30 15:12:08 2008 ranaSummaryIOOHistory of the MC abs length
> I was notified by Rob and Rana that there were many measurements of the MC abs length (i.e. modulation
> frequencies for the IFO.) between 2002 and now.

I will just add that I think that the Marconi/IFR has always been off by ~150-200 Hz
in that the frequency measured by the GPS locked frequency counter is different from
what's reported by the Marconi's front panel. We should, in the future, clearly indicate
which display is being used.
  829   Tue Aug 12 19:48:24 2008 JenneUpdateIOOPRM standoff is in....mostly
Yoichi, Jenne

The missing PRM standoff is now partially installed. The standoff is in, and the wire is in the groove, but we have not finished adjusting its position to make the PRM stand up straight. It turns out to be pretty tricky to get the position of the standoff just right.

We have set up a HeNe laser as an oplev on the flow bench (which we checked was level) in the clean assembly room, and are using it to check the pitch of the mirror. We set a QPD at the height of the laser, and are looking at the single-reflected light. When the single-reflected light is at the same height as the center of the QPD, then the mirror is correctly aligned in pitch. (Actually, right now we're just trying to get the single-reflected light to hit the diode at all...one step at a time here).

We'll continue trying to align the PRM's standoff in the morning.
ELOG V3.1.3-