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ID Date Author Type Categoryup Subject
  176   Thu Dec 6 19:19:47 2007 AndreyConfigurationSUSSuspension damping Gain was restored

Suspension damping gain was disabled for some reason (all the indicators in the most right part of the screen C1SUS_ETMX.adl were red), it is now restored.
  213   Wed Dec 26 15:00:06 2007 ranaUpdateSUSETMY tripping
Steve mentioned to me that ETMY is still tripping more than ETMX. The attached DV plot
shows the trend of the watchdog sensors; essentially the RMS fluctuations of the shadow
sensors. (note** DV can make PNG format plots directly which are much better than JPG
when making plots and much smaller than PS or PDF when plotting lots of points).
  214   Wed Dec 26 15:12:48 2007 ranaUpdateSUSETMY tripping
It turned out that the ETMY POS damping gain was set to 1.0 while the ETMX had 3.8.

I put both ETMs to a POS gain of 4 and then also set the PIT, YAW and SIDE gains for
ETMY. Let's see if its more stable now.

In the next week or so Andrey should have perfected his damping gain setting technique
and the numbers should be set more scientifically.
  216   Thu Dec 27 13:08:04 2007 ranaUpdateSUSETMY tripping
Here's a trend from the last 2 days of ETMX and ETMY. You can see that the damping gain increase
has made them now act much more alike. Problem fixed.
  220   Thu Jan 3 08:53:55 2008 steveUpdateSUSetmy vs etmx
Rana have corrected sus gain damping setting of ETMY 8 days ago

gain settings: pos, pit, yaw & sd
etmx: 4,2,2,& -16
etmy: 4,2,2,& 50
  222   Thu Jan 3 09:55:11 2008 steveUpdateSUSetmy sus damping restored
ETMY watch dog was lost at midnight
  225   Fri Jan 4 08:42:03 2008 steveUpdateSUSetmy trips again
ETMY sus damping tripped at 6am this morning
It was reset. We should put an accelerometer to the south end to see
the garbage dumping effect.
  226   Mon Jan 7 09:01:39 2008 steveUpdateSUSBS sus damping restored
The BS sus damping was lost at 8am Sunday morning.
  232   Thu Jan 10 10:38:02 2008 steveUpdateSUSetmy damping restored
The IST building onstruction has really started yesterday and continuing today with big heavy ground breaking
machinary. The MC is holding lock and the suspentions are hanging on.

ETMY does not like this.

SUS-MC2_LLPD_VAR monitor is a good indicator of seismic activity on this 12 days plot
  233   Thu Jan 10 12:08:23 2008 steveUpdateSUSwhy did the BS move?
  235   Thu Jan 10 15:04:04 2008 steveUpdateSUSilluminator light effect on BS position
The bs chamber illuminator light was turned on this morning and left on.
Earlier on Rana noticed that the bs moved.
I follwed up to see what happened. I turned off oplev servo and tried to recenter on oplev pd
by adjusting pitch and yaw biases. It did not move. I looked at suspention and realized that the
illuminator was still on. I turned it off and to my amazement the the AP spot started flashing
  237   Mon Jan 14 14:41:09 2008 steveUpdateSUSetmy sus damping restored & mz relocked
Tree days trend of MZ HV drift is typical these days.
So as the etmy sus inability to hold damping for longer then 2-3 days.
  242   Wed Jan 16 18:24:41 2008 ranaUpdateSUSETMY Watchdog
Because Steve keeps complaining about ETMY, I looked at some minute trend to see if there was something exotic happening at that time. It looks like there is some tremendous seismic activity to make it happen.

The trend shows that there is nothing special happening on the ETMX accelerometer or the ETMX suspension. At the same time, however, there is a huge jump in the ETMY sensors and therefore the watchdog signal. Whenever the watchdog value goes above 140, it trips.

After Andrey moves some accelerometers over to the Y end we can see the effect more directly.
  256   Wed Jan 23 12:31:36 2008 AndreySummarySUSDissapointing Results of XARM optimization (PDF-file)

I attach a PDF-file which summarizes briefly the results of measurements/calculations of Q-factors for ITMX mass as a function of suspension damping gain,

and this file contains the results of measurements of RMS peaks on the values of suspension gains of ITMX and ETMX (see ELOG entries from December 2007, specifically #202, #199, #194)),
but now those dependences are plotted in Q-ITMX and Q_ETMX axes.

Unfortunately, there are no clear narrow areas of minimum in those dependences (that explains the sad title of this ELOG entry).

The attached pdf-file can be shown as a short presentation for a wall during our Wednesday meeting.
  260   Thu Jan 24 20:03:40 2008 AndreyConfigurationSUSChanges to Dataviewer channels (XARM)

1) Good news. I added a chanel "C1:SUS-ETMX_POS" to Dataviewer.

I followed the instructions from WIKI-40:

modify the file "C1SUS_EX.ini" in /cvs/cds/caltech/chans/daq,
then telnet to fb40m,
then "click the appropriate blue button on the DAQ MEDM screen".

So, I can now read a signal from the channel "C1:SUS-ETMX_POS" in Dataviewer,

and this allows me to measure Q-factors of ETMX this evening (make similar work for what I did on Tuesday for ITMX).


2) BAD NEWS. While "clicking the appropriate blue button" on the DAQ MEDM screen,
namely CODAQ_DETAIL,adl screen, I obviously clicked some blue button that I should not have clicked,
and as a result the signal in Dataviewer from the channel "C1:SUS-ITMX_POS" has disappeared (it is now a straight line).


Description of what has happened and of my wrong actions:
I had two channels opened in Dataviewer simultaneously (both "C1:SUS-ETMX_POS" and "C1:SUS-ITMX_POS"),
and after clicking some blue button on CODAQ_DETAIL,adl screen, the signal from "C1:SUS-ITMX_POS" became
a straight line,
while signal from "C1:SUS_ETMX_POS" continued to be a random noise.

I was scared that I made worse for the channels and for Dataviewer, and I started clicking random blue buttons chaotically hoping that it will restore the signal from "C1:SUS-ITMX_POS". Random clicking on arbitrary blue buttons did not return the signal.

As the channel "C1:SUS-ETMX_POS" works normally, I will be measuring Q-factors of ETMX tonight,
but it is obvious that someone else (Rana, Robert,Steve?) needs to restore the correct settings for "C1:SUS-ITMX_POS".

Moreover, as I was clicking chaotically all the blue buttons on CODAQ_DETAIL,adl screen, someone else (Rana, Robert, Steve?) will need to check somehow that I did not destroy signals from some other channels.

I apologize for the negative consequences of my channel adding,

but Rana asked me in the very beginning in September to let others know if I spoil something, so that others would be aware of it and could fix the problem.

Again, I apologize and hope that the problem is not very serious.
  265   Fri Jan 25 10:14:35 2008 robConfigurationSUSChanges to Dataviewer channels (XARM)

Quote:

2) BAD NEWS. While "clicking the appropriate blue button" on the DAQ MEDM screen,
namely CODAQ_DETAIL,adl screen, I obviously clicked some blue button that I should not have clicked,
and as a result the signal in Dataviewer from the channel "C1:SUS-ITMX_POS" has disappeared (it is now a straight line).


Description of what has happened and of my wrong actions:
I had two channels opened in Dataviewer simultaneously (both "C1:SUS-ETMX_POS" and "C1:SUS-ITMX_POS"),
and after clicking some blue button on CODAQ_DETAIL,adl screen, the signal from "C1:SUS-ITMX_POS" became
a straight line,
while signal from "C1:SUS_ETMX_POS" continued to be a random noise.

I was scared that I made worse for the channels and for Dataviewer, and I started clicking random blue buttons chaotically hoping that it will restore the signal from "C1:SUS-ITMX_POS". Random clicking on arbitrary blue buttons did not return the signal.

As the channel "C1:SUS-ETMX_POS" works normally, I will be measuring Q-factors of ETMX tonight,
but it is obvious that someone else (Rana, Robert,Steve?) needs to restore the correct settings for "C1:SUS-ITMX_POS".

Moreover, as I was clicking chaotically all the blue buttons on CODAQ_DETAIL,adl screen, someone else (Rana, Robert, Steve?) will need to check somehow that I did not destroy signals from some other channels.

I apologize for the negative consequences of my channel adding,

but Rana asked me in the very beginning in September to let others know if I spoil something, so that others would be aware of it and could fix the problem.


I eventually resolved the situation by restarting the c1susvme1 processor, which had somehow got confused by the clicking random blue buttons chaotically. The data acquisition should be working again.
  286   Wed Jan 30 13:09:55 2008 AndreyUpdateSUSNew results for XARM (pdf)

See attachments: pdf-presentation with plots in "true" axes Q_ETMX and Q_ITMX, and seismic backgound measurement.

Results that were shown a week ago turned out to be not sad at all!
  305   Sat Feb 9 13:32:07 2008 JohnSummarySUSAll watchdogs tripped
When I arrived this afternoon the watchdogs had tripped on all optics. I reset them and enabled the coil currents.

I had to adjust the alignment of the mode cleaner to get it to lock.
  306   Sun Feb 10 20:47:01 2008 AlanSummarySUSAll watchdogs tripped
A moderate earthquake occurred at 11:12:06 PM (PST) on Friday, February 8, 2008.
The magnitude 5.1 event occurred 21 km (13 miles) NW of Guadalupe Victoria, Baja California, Mexico.
http://quake.wr.usgs.gov/recenteqs/Quakes/ci14346868.html
  323   Tue Feb 19 15:21:47 2008 AndreyUpdateSUSEarthquake tripped watchdogs in ETMY, ITMY

According to the web-page http://earthquake.usgs.gov/eqcenter/recenteqsus/Quakes/ci14351140.php ,

there was a 5.0 earthquake in northern Baja California in Mexico at 02.41PM earlier today.

This earthquake made an effect on our watchdogs for ETMY and ITMY (their currents exceeded maximal values).
Watchdogs for ITMY are now restored back,
and it is taking more time for a "side degree" for ETMY to calm down,
it is still (40 minutes after the kick) swinging a lot with amplitude ~ 200mV.
  404   Wed Mar 26 13:41:53 2008 AndreyHowToSUSModification of ''C1DRIFT_MONITOR''
I learned how to modify the drift-monitor in MEDM so that values on it change colors from green to yellow to red depending how much is the fluctuatioin (deviation) of the value from its mean nominal value.

In order to do this, I used the following eight commands:

tdswrite CHANNEL_NAME.HIHI VALUE
tdswrite CHANNEL_NAME.HIGH VALUE
tdswrite CHANNEL_NAME.LOW VALUE
tdswrite CHANNEL_NAME.LOLO VALUE
tdswrite CHANNEL_NAME.HHSV 2
tdswrite CHANNEL_NAME HSV 1
tdswrite CHANNEL_NAME LSV 1
tdswrite CHANNEL_NAME LLSV 2

where CHANNEL_MAME is the name of the channel the value of which is indicated on the MEDM screen C1DRIFT_MONITOR, for example
C1:SUS-MC1_SUSPOS_INMON, and VALUE is numerical value that I assigned to the channel parameters.

By now I modified nine mode-cleaner channels (POS, PITCH and YAW channels for MC1, MC2 and MC3) and 6 channels for ITMX and ITMY.

Note that as we have problems this week with computer C1SUSVM, namely ''c1susvme2'' is not working, indicators for MC2 in the drift-monitor do not change colors today although they should.

In order to judge which values should be established as reasonable deviations from the average nominal values, I was looking into Dataviewer trends for the channels that are in the drift-monitor.


In the future indicators for channels ETMX and ETMY, BS, PRM, SRM should be modified in complete analogy with what I did already for MC and for ITM. So, I have modified 3*5 = 15 channels, and 3*5 = 15 channels are left for the future.

Note that (as far as I understand) instead of commands "tdswrite" it is absolutely legitimate to use commands "ezcawrite".
  425   Fri Apr 18 16:02:58 2008 alexUpdateSUSend station sus front-end bug fix
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.
  426   Fri Apr 18 16:27:04 2008 robUpdateSUSend station sus front-end bug fix

Quote:
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.


But where is the code?
  431   Sun Apr 20 23:39:57 2008 ranaSummarySUSMC1 electronics busted
I spent some time trying to fix the utter programming fiasco which was our MCWFS diagonalization script.

However, it still didn't work. Loops unstable. Using the matrix in the screen snapshot is OK, however.

Finally, I realized from looking at the imaginary part of the output matrix that there was something
wrong with the MC1 drive. The attached JPG shows TFs from pit-drives of the MC mirrors to WFS1.

MC1 & MC3 are supposed to have 28 elliptic low pass filters in hardware for dewhitening. The MC2
hardware is different and so we have given it a software 28 Hz ELP to compensate. But it looks like
MC1 doesn't have the low pass (no phase lag). I tried switching its COIL FM10 filters to make it
switch but no luck.

We'll have to engage the filters to make the McWFS work right and to get the MC noise down. This
needs someone to go check out the hardware I think.

I have turned the gain way down and this has stabilized the MC REFL signal as you can see from the StripTool screen.
  435   Tue Apr 22 10:59:24 2008 robUpdateSUSMC1 electronics busted

Quote:
I spent some time trying to fix the utter programming fiasco which was our MCWFS diagonalization script.

However, it still didn't work. Loops unstable. Using the matrix in the screen snapshot is OK, however.

Finally, I realized from looking at the imaginary part of the output matrix that there was something
wrong with the MC1 drive. The attached JPG shows TFs from pit-drives of the MC mirrors to WFS1.

MC1 & MC3 are supposed to have 28 elliptic low pass filters in hardware for dewhitening. The MC2
hardware is different and so we have given it a software 28 Hz ELP to compensate. But it looks like
MC1 doesn't have the low pass (no phase lag). I tried switching its COIL FM10 filters to make it
switch but no luck.

We'll have to engage the filters to make the McWFS work right and to get the MC noise down. This
needs someone to go check out the hardware I think.

I have turned the gain way down and this has stabilized the MC REFL signal as you can see from the StripTool screen.


This was just because the XYCOM was set to switch the "dewhites" based on FM9 rather than FM10. To check whether the hardware ellipDW filters were engaged, I drove MC1 & MC3 in position (using the MCL bank), and looked at the transfer functions MC2_MCL/MC1_MCL and MC2_MCL/MC3_MCL. This method uses the mode cleaner length servo to enable a relatively clear transfer function measurement of the ellipDW, modulo the loop gain of MCL and the fact that it's really hard to measure an ELP cascaded with a suspension. The hardware and the switching appear to be working fine.

It's now set up such that the hardware is ENGAGED when the coil FM10 filters are OFF, and I deleted all the FM10 filters from the coils of MC1 and MC3. Since we don't switch these filters on and off regularly, I see no need to waste precious SUS processor power on filters that just calculate "1".
  436   Tue Apr 22 16:17:48 2008 robUpdateSUSend station sus front-end bug fix

Quote:
installed and started new susEtmx.o and susEtmy.o to fix a problem with ETMY optical lever variables.


What Alex means is that the EPICS values for the ETMY optical levers were being clobbered in the RFM. The calculations were being done correctly in the FE, so the DAQ/testpoints were working--it was just the EPICS/RFM communication via c1losepics that was bugged. This was a result of the recent SUS code changes to accept inputs from the ASS for adaptive feedforward.
  462   Thu May 1 08:31:51 2008 steveUpdateSUSearthquake trips etmy & mc1
Earthquake at Lake Isabel magnitude 4.4 at 1am today shakes the 40m
ETMY and MC1 watchdogs tripped.
Sus damping restored.
  472   Fri May 9 08:40:24 2008 steveUpdateSUSETMY sus damping restored
ETMY lost damping at 19:10 last night.
There was no seismic event than.
Sus damping was restored this morning.
  474   Tue May 13 10:15:52 2008 steveUpdateSUSrestored damping of BS & PRM
I think our janitor was cleaning too heavy handedly.
The BS and PRM sus damping were lost.
They were restored.
  485   Sun May 18 18:44:48 2008 ranaSummarySUSOptical Lever SUM Trend - 80 days
I used the OL-Trend.xml dataviewer template to make this plot. Looks like the ETMY optical lever
slowly degraded over the last few months and then finally died 10 days ago. Would someone please
replace this laser and tune the lens position to minimize the spot size on the quad?
  487   Mon May 19 11:49:57 2008 steveUpdateSUSetmy oplev laser replaced
The 9 years old Uniphase HeNe was replaced by a new JDSU 1103P
Power output ~3.5 mW, reflected light back on qpd ~140 microW, 12,800 counts
Andrey will get the ~2.5 mm od spot on the qpd smaller by replacing
the f1000 lens
  499   Sun May 25 22:33:00 2008 ranaUpdateSUSETMY Oplev Work
I found the ETMY table in disarray and put the panels back on and put the ETMY OL laser back on the quad.

The next thing to do is clean up the table (there's a lot of junk on it) and then put in a lens within
6" of the laser to focus the beam on the quad (no metal diving boards and the lens should be either
uncoated (from our Edmunds collection) or a red lens, not 1064).

Then we have to put the beam cover back on between the viewport and the table.
  504   Thu May 29 16:32:09 2008 steveUpdateSUSetmy oplev is back
I relayed the optics for ETMY-oplev as shown in pictures below.
The reflected beam goes directly to the qpd
  507   Fri May 30 12:37:45 2008 robUpdateSUSetmy oplev is back

Quote:
I relayed the optics for ETMY-oplev as shown in pictures below.
The reflected beam goes directly to the qpd


I turned on the servo. UGFs in PIT and YAW are ~3Hz. I had to flip the sign of the YAW.
  629   Thu Jul 3 12:36:05 2008 JonhSummarySUSETMY watchdog
ETMY watchdog was tripped. I turned it off and re-enabled the outputs.
  676   Tue Jul 15 19:15:57 2008 ranaSummarySUSETMX Dewhitening characterization
Since the boys found that the ETM dewhitening transient was kicking the IFO out of lock we
decided to investigate.

First, we wrote a script to diagnose and then tune the DC gain of the dewhitening filters'
digital compensation filter (a.k.a. FM9 or SimDW). It is in the scripts/SUS/ directory
and is called dwgaintuner. It puts in an offset on each coil's DAC channel and
then reads back the Vmon on the coil driver with the DWF on and off. It reports the ratio of these
voltages which you can then type into the FM9/SimDW filter's gain field. We learned that the
difference between the analog DWF path and the bypass path was ~3% (which is consistent with
what you expect from the use of 1% resistors). We need to repeat this for all of the rest of
the suspended optics except for MC1 and MC3.

This Vmon method is better than what's used at the sites so we will export this new technology.

The attached plot shows some switching transients with only the local damping on:
BLUE:   Output of filter bank during an FM9 turn off. This is the transient which goes to the DAC.
        The transients are mostly of the same magnitude as this.
RED:    This is the input of the filter module during another such transient.
GREEN:  Tried another switch; this time I filtered the time series in DTT by typing the SimDW into
        the Triggered Time Series filter field. This should be simulating what comes out of the
        output of the DW board - to convert to volts multiply by 15/32768.
PURPLE: Same kind of filtering as the GREEN, but with also a double 30 Hz highpass to remove the low
        frequency damping control signals. You can see that the total transient is only ~5 counts
        or ~1 mV at the coil driver output. This is comparable to the relative offset in the bypass
        and filter paths.
  755   Tue Jul 29 13:54:08 2008 ranaUpdateSUSETMY and PRM have EQ related problems
The attached trend shows that ETMY and PRM both had large steps in their sensors
around the time of the EQ and didn't return afterwards. The calibration of the
OSEM sensors is ~0.5 mm/V. The PRM sensors respond when we give it huge biases
but there is very little change in the ETMY. Almost certainly true that the
optics have shifted in their wire slings and that we will have to vent to
examine and repair at least ETMY.

Jenne is looking at the spectra of the other suspensions to see if there is
other more subtle issues.
  756   Tue Jul 29 14:38:02 2008 robUpdateSUSETMY and PRM have EQ related problems

Quote:
The attached trend shows that ETMY and PRM both had large steps in their sensors
around the time of the EQ and didn't return afterwards. The calibration of the
OSEM sensors is ~0.5 mm/V. The PRM sensors respond when we give it huge biases
but there is very little change in the ETMY. Almost certainly true that the
optics have shifted in their wire slings and that we will have to vent to
examine and repair at least ETMY.

Jenne is looking at the spectra of the other suspensions to see if there is
other more subtle issues.


Some additional notes/update:

ETMY, PRM, & MC2 had OSEM signals at a rail (indicating stuck optics). Driving the optics with full scale DAC output freed ETMY and MC2, so while these may have shifted in their slings it may be possible to avoid a repair vent. PRM is still stuck. One OSEM appears to respond with full range to large drives, but the other three face OSEMS remain disturbingly near the rail (HIGH, which is what would happen if a magnet fell off).
  759   Tue Jul 29 19:53:19 2008 KojiUpdateSUSPRM photos from the south window
Steve and Koji

We took some photos of PRM from the south window.
You can see one of the side magnets, a wire stand-off, and the wire itself from the round hole.
So, the wire looks OK.

For the coils, we could see only one coil. The magnet is apparently too high.
  762   Wed Jul 30 00:42:04 2008 ranaUpdateSUSTrends and file formats
I propose that we do not use .eps format but .pdf instead. For images like the plots Sharon
has below we should use only .png and for pictures like what Steve posted, use JPG or PNG.

PDF is a standard and light weight. PNG is very good for plots/lines and is lossless. JPG does
a good job with regular camera pictures because we don't really care about the compression
loss on those.

Here's a trend of the UL sensors for all the optics - conversion is 32768 cts / mm. You can see
that the quake was just before 19:00 UTC (noon our time). The events an hour after are when
Rob, Jenne, and I start exciting the optics to shake them loose - wanging the pit/yaw sliders
around is not violent enough and so I injected a 130000 count sine wave at 0.5 Hz so as to
create a high force square wave. This seems to have worked for ETMY but no such luck yet with
the others.
  763   Wed Jul 30 01:08:50 2008 ranaSummarySUSSUS Drift Screen
This is a snap of the SUS Drift screen with all of the optics biases set back to their nominal
values except for the MC which Rob aligned and I didn't feel like mis-aligning. The reference
on the screen is from 3/25 when Andrey felt that Rob had a good IFO alignment.

Anything more than a few thousand is significant and more than 10k means something is wrong:



I wailed on the PRM for awhile and was able to loosen it up a little. The LL & LR sensors now
show some life one the dataviewer. The UL & UR are still railed ~1.6 V so that means that the
optic is pitched back. With aggressive pitch wailing I can see the PRM's ULR/UR sensors go
rail to rail so that means that the magnets are still on - although they may be half busted.
If they're OK we should be able to just re-sling this guy.


Did the same on SRM. The OSEM values have shifted on these, but not disastorously. The SIDE,
however, is completely unresponsive. The little signal I see when driving is is probably just
capacitive pickup in the cables. Have to vent to fix this one.


ITMX Has good life in all but the LR & UR channels. They respond, but the signal is very weak.
Seems like these magnets have not fallen off but that they are not between the LED/PD anymore.


ITMY seems ok. Check the spectra to be sure.


BS seems ok as well. Swings freely and no kinks in the swinging sensor waveforms. Check the spectra.
  773   Wed Jul 30 18:45:01 2008 ranaConfigurationSUSNew SUS Drift Technology
I updated the SUS DRIFT screen again, this time with a new feature.

I used Rolf's idea for the AdvLIGO status system and just made the nominals be an
unused sub-field (.SVAL) of the main INMON record. Then I wrote a .csh script to
use tdsavg to average the current INMON vals and insert that as the .SVAL. The next
script should read the .SVAL and set the HIHI and LOLO based on this.

Of course, the values I have just entered are no good because our suspensions are in
a bad state but we can run this script (SUS/setDriftNoms) next time things are good.

And...even better would be if someone were to do the same but used mDV to grab the
minute trend in the past good times instead of the tdsavg (which can't go in the past).
  785   Sat Aug 2 18:37:41 2008 ranaUpdateSUSOSEM Spectra

The attached PDF file is from the .xml files that I found from 7/30. Looks like someone
took some free swinging data and even made nice plots but didn't elog it. Raspberry for you.
The data files are saved in Templates/FreeSwinging/{ETMX,ETMY,etc.}/2008_07_30.xml

The top left plot on the multi-page file all have the same scale so you can see what's happened.
The peaks should all be as measured by Busby in Sep '06
but instead they are as you see here.
  797   Tue Aug 5 10:23:00 2008 steveUpdateSUSearthquake and venting effects
atm 1, EQ
atm 2, vent 7 days later: venting kicks optic into place to be free,
PRM: LR magnet gets pushed in and it is stocked, side in free
  799   Tue Aug 5 12:52:28 2008 YoichiUpdateSUSITMX, SRM OSEM spectra
Free swinging spectra of ITMX and SRM.
ITMX seems to be ok after yesterday's work, though the OSEM DC values are still a bit off from the normal value of 0.9.
(ITMX OSEM values: UL=1.12, UR=1.38, LR=0.66, LL=0.41, SIDE=0.66)
SRM is still clearly wrong.
  803   Wed Aug 6 13:15:57 2008 YoichiUpdateSUSSRM ETMX freeswing spectra
After yesterday's work on the SRM, I took free swinging spectra of SRM.
The eigen modes look ok. But there are many other peaks which were not present in vacuum.
Some of those peaks may be resonances of the air inside the chambers and the pipes.
However, the peaks around 0.2Hz are too low frequency for those air compression modes.
I took the ETMX spectra at roughly the same time. I chose ETMX because we have not touched it after the vent.
ETMX also shows some extra peaks but the frequencies are different.
  806   Wed Aug 6 22:19:07 2008 YoichiUpdateSUSBS alignment
Koji, Yoichi

We realized that we did not pay attention to the BS alignment while working on the alignment of the ITMX today. Because we were injecting the ALM laser (absolute length measurement laser) from the AS port, the ITMX alignment depends on the BS alignment.
The BS optical lever was not centered and the sum was about 2000cnt, which is low compared, for example, to the SRM oplev.
So we were not sure if the BS was in a good alignment or not.
So we decided to move the BS to center the QPD.
In doing so, we also moved the ITMX so that we do not lose the ALM laser beam coming back to the AS port.
When the BS oplev was centered, the sum of the QPD was still about 2000. So it was not far off centered.
After the tweaking, we were able to see some interference between the light reflected by the ITMY and ITMX at the AS port (actually this is the bright port for the ALM laser). By tweaking the ITMY, we were able to see Michelson fringes at the AS port.
If we believe the ALM laser alignment is still good after the vent, the ITMX, ITMY, BS and SRM should be now in a good alignment condition.
The OSEM values for the ITMX, BS, SRM seem to be ok (0.9+/-0.2). The ITMY LL is a bit low (~ 0.45).
  807   Thu Aug 7 10:07:13 2008 YoichiUpdateSUSFree swinging OSEM spectra
Looks like there are more extra peaks in the SRM than other optics.
Maybe because it is closer to the door ?
  808   Thu Aug 7 10:27:59 2008 ranaUpdateSUSFree swinging OSEM spectra
Sometimes we see extra peaks in the OSEM spectra coming from a beat between the regular eigenmodes.
This probably comes from the OSEM shadow sensor not being entirely linear - the nonlinearity is
greatly increased if the magnet is not perfectly centered in the LED beam. So the beats are
probably there at some level in all of them; usually below the noise.
  810   Thu Aug 7 12:20:52 2008 YoichiUpdateSUSPRM stand-offs and wire
We removed the side OSEM of the PRM so that we can see the stand-off on the farther side.

Attachment 1: Farther side stand-off from an angle before removing the OSEM
Attachment 2: Farther side stand-off through the empty OSEM hole.
Attachment 3: Near side stand-off

The wire is definitely in the near side stand-off groove.
Probably the wire is in the groove also on the farther side.
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