Fri Feb 03 19:57:20 2012

Fri Feb 03 20:25:19 2012 :   Aligned all SUS to center their OL beams

Fri Feb 03 20:29:21 2012:    Aligned all SUS to make OL_PIT = 0.5

As usual, I noticed several bad things within 30 seconds of sitting in front of the workstation. Today its that there are OFF or missing filters on the MC TRANS.

is this the normal state? Screenshot attached.

Schott, green welding glass, shade 14, 3 mm thick  was measured in the beam path of 1.2W, S polarization of 1064nm at ~1 mm diameter size as MC reflected path.

Absorption 95%, R 5% at incident angle 25-50 degrees. It looks like the perfect material for beam trap.

The reason I've killed the c1lsc kernel was the following - when the code starts to run, it initializes some parameters and this takes ~0.2 msec per dof. Now, the old code did nothing with a DOF if C1:OAF-ADAPT_???_ONOFF == OFF. My code still initialized the parameters but then does nothing because no witness channels are given. But it spends 8*0.2 = 1.6 msec for initializing all 8 dof. As the code is called with frequency 2k, this was the reason for crashing. Now I've corrected my code, it compiles, runs and does not kill c1lsc. However, the old code would also kill the kernel if all DOF are filtered. So, when we'll use all 8 DOF, we'll have to split variable initialization.

But this is not the biggest problem. C1OAF model must be corrected, because, as for now, all 8 DOF call the same ADAPT_XFCODE function. As this function uses static variables, they will be all messed up by different DOF signals.

When I left this morning, Steve was still working with the MC and it was unlocked anyway, I could not check it. By "fine" I meant only watchdogs. The thing is that before starting to work with c1lsc I turned off all the coils. Crazyness that Steve saw was after I turned them on back after reboot. This is a confusing thing - restarting models on c1lsc and burt restoring them is not enough. After I did it, everything at the STATUS MEDM screen was green, but the C1:SUS-???_??PD_VAR values went up after turning on coils. So sus and lsc communicated in a bad manner after the reboot. After restarting x02 model, the watchdogs were fine again.

Cold LED lights replaced hot halogen ones. Flat LED MYAL 6S,  model #112560002  24VAC

This is a LATE ENTRY.  They were purchased  in Jan 2010 and installed 6 of them around May 2010

[Jenne, Den]

We moved the MC approximately back to where the sensors for each optic used to be (mostly touching MC2, but a little bit of MC1 to help the refl get back to its max value).  MC is now locked, and with the help of the WFS it's back to nominal.  I forgot to disable the WFS, so I think we aren't perfectly aligned, but we're close enough for the WFS to get us the rest of the way.  We're heading over to JClub right now, so we're going to leave it as-is.

 Rough draft of      updated interlock drawing by Ben is here.

The mode cleaner is a little misaligned in pitch, and is very misaligned in yaw.  The lowest order mode that is flashing is TEM11.

I had a look-see at the SUS sensors, to see if there were any big jumps.  There were moderately sized jumps on all 3 mode cleaner optics.

The MC's lockloss was at ~8:22am this morning, and went along with a giganto kick to the optics.  Steve tells me that Den might have been kicking up optics while doing computer things this morning, before Steve reminded him to shut off the watchdogs.  However, Steve was also taking phots/measuring things near MC Refl, so maybe he's not totally absolved of blame.  But this really looks like the optics settled to different places after big kicks.

I'm going to try to align the MC mirrors to get back to the sensor numbers from early this morning before chaos began.

Reminder / Moral:  Everything cannot be considered to be "working fine" if the MC isn't locking.  See if you can figure out why, and especially if it's something that you screwed up, either fix it, or better yet, ask for help and learn how to fix what you broke.

This morning I killed again c1lsc kernel with the new realization of fxlms algorithm. It works fine with gcc compiler during the tests. However, smth forbidden for the kernel is going on. I'll spend some more time on investigatin it. Interesting thing is that I did not even pressed "On" at the OAF MEDM screen to make the code running. c1lsc suspended even before. May be there is some function-name mismatch.

After c1lsc suspention I recomiled back non-working code and rebooted c1lsc. c1sus is also bad after c1lsc reboot as they communicate. I killed x04, lsc, ass, oaf models on the c1lsc computer and sus, mcs, rfm, pem on the c1sus computer. Then I restarted x02 model and restored its burt snapshot from 08:07. After I started all models back and restored their burt snapshots from 08:07. Then I diag reset all started models.

Before starting new fxlms code I've shutted down all the optics so that possible c1lsc suspention would not make them crazy. After reboot I turned the coils back. Everything seems to work fine.

 BEN fixed the interlock.  The laser is turned ON. Thanks for all, Rich and Sam who came over to help. Atm1

All emergency shut- off switches, lights and door indicators are working at this moment. More about this tomorrow.

Atm2, PSL enclosure interlock jungle without REAL schematic drawing.....at this point.... We all agreed it is easier to redo the hole thing than find the problem

Atm3, Emergency shut off switches and illuminated signs from  entry doors to AC on-off box  ( Use this switches in emergency ONLY,  otherwise leave alone , even it is labeled obsolete !)

Summery: I still do not really know what was wrong.

The 2W PSL laser is turned off.  The danger laser lights are not illuminated at the entry doors because of malfunctioning electronic circuit!!!

Laser safety glasses are still required!  Other lasers are in operation!

[Steve/ Kiwamu]

 We found that the laser had completely shut off for ~ 4 hours even with all the PSL doors closed.

We are guessing it is related to the interlock system and Steve is working on it to fix it.

 The 2W Innilight shutdown shut when I opened side door for safety scan. This was not a repeatable by opening -closing side doors later on. Turned laser on, locked PMC and MC locked instantly. The MC was not locked this moring and it seemed that the MC2 spot was still some high order mode

like yesterday. MC lock was lost when the janitor bumped something around the MC.

[Rana / Kiwamu]

We tried to set some parameters for the suspension drift monitor but the old matlab script, which automatically sets the values, didn't run because it uses the old mDV protocol.

The attached link below is a description about the script.

https://wiki-40m.ligo.caltech.edu/Computers_and_Scripts/All_Scripts#Drift

It needs to be fixed or upgraded by pynds.

 Roscolux filter films  #74 night blue,  0.003" thick  and  #26 light red, 0.002" thick  were measured in the beam path of  ~6 mm diameter,  1W 1064 nm .

T 90%  + - 5% at 0-30 degrees of  incident angles and R ~10 % 

These sandwitched thin films of policarbonate-polyester filters are not available in thicker forms. Rosco is recommending them to be cooled by air if used in high power beam.

These filters did not get warm at all in 1W, so absorption must be very small.

 The PMC pointing has changed, so MC is resonating in high order modes.

Here is a hypothetical scenario which could make the glitches in the LSC error signals. It can be considered as a 4 step phenomenon.

        (1) up conversion noise due to a large motion at 3 Hz

   => (2) rms level exceeds the line width (a.k.a. linear range) in some LSC sensors

   => (3) unlocks some of the DOFs  in a moment

   => (4) glitches due to the short unlock.

- - plan  - -

 In order to check this hypothesis the low finesse PRMI must serve as a good test configuration.

What I will do is to gradually decrease the offset in MICH such that the finesse of PRMI becomes higher.

And at each different finesse I will check the spectra, glitch rate, and etc.

The Yarm green laser really wanted to lock on a 01/10 mode, so Kiwamu suggested I go inside and realign the green beam to the arm.  I did so, and now it's much happier locked on 00 (the Yarm is resonating both green and IR right now).

Sitting down to start cavity measurements, I found both ITMs tripped.  It must have happened a while ago (I didn't bother to check dataviewer trends) because both had rms levels of <5 counts, so they've had a while to sit and quiet down.

 In order to get a better price from Vlier's Tom Chen I changed Ti body back to SS304L-siver plated and music wire spring. The price is still ~$120 ea. at quantity 50

I will talk to Mike G about modifying the  McMaster plunger with a hex nut.

I went through various IFO configurations to see if there are glitches or not.

Here is a summary table of the glitch investigation tonight. Some of the cells in the table are still not yet checked and they are just left blank.

        Low finesse PRMI      

The low finesse PRMI configuration is a power-recycled MIchelson with an intentional offset in MICH to let some of the cavity power go through MICH to the dark port.

To lock this configuration I used ASDC plus an offset for MICH and REFL33 for PRCL.

The MICH offset was chosen so that the ASDC power becomes the half of the maximum.

In this configuration NO glitches ( a high speed signal with an amplitude of more than 4 or 5 sigma) were found when it was locked.

Is it because I didn't use AS55 ?? or because the finesse is low ??

Also, as we have already known, the up conversion noise (#6212) showed up -- the level of the high frequency noise are sensitive to the 3 Hz motion.

I did a fine alignment on the Y end green setup. The green light became able to be locked again.

After I recovered the lock of PMC, I found that the PMC transmission was quite low. It was about 0.26 in the EPICS display.

I zeroed the PSL temperature feedback value which had been -2.3 and then the PMC transmission went back to a normal value of 0.83.

I believe it was because the PSL was running with two different oscillation modes due to the big temperature offset.

The mode cleaner is super unhappy.  It's rocking around at ~1Hz.

I turned off the WFS and turned them back on after the MC was locked, and it seems a little happier now.  At least it's not falling out of lock ~1/minute.

 The alignment is finished after the realization that the 3rd steering mirror had to be adjusted too.

The input power increased from 1.2 to 1.4 mW

It started with fire alarm test yesterday at 14:50 All alarms are  functioning VERY loud and their flashers are bright. Evacuation drill followed. We assembled at north west corner of the 40m building and counted 6 heads.

Nobody was left sleeping inside. Bob carried the success report of the drill to PMA office immediately.

During the Y arm ALS I found that the noise of the AS55 demod signal was worse than that of POY11 in terms of the Y arm displacement.

There is a bump from 500 mHz to 100 Hz in the AS55 signal while POY11 didn't show such a structure in the spectrum.

The plot below is the noise spectra of the Y arm ALS. The arm length was stabilized by using the green beat-note fedback to ETMY.

In this measurement, POY11 and AS55 were served as out-of-loop sensors, and they were supposed to show the same noise spectra.

In the plot It is obvious that the AS55 curve is louder than the POY curve.

Indeed the glitches show up in the analog demodulated signals. So it is not an issue of the digital processing.

With an oscilloscope I looked at the I/Q monitor outputs of the LSC demodulators, including REFL11, REFL33, REFL55, POY11, AS55 while keep locking the carrier-resonant PRMI.

I saw some glitches in REFL11, REFL55 and AS55. But I didn't see any obvious glitches in REFL33 and PO11 because the SNR of those signals weren't good enough.

(some example glitches)

The attached plot below is an example shot of the actual signals when the carrier resonant PRMI was locked.

The first upper row is the spectrogram of REFL11_I, REFL55_I, REFL33_I and AS55_Q in linear-linear scale.

The second row shows the actual time series of those data in unit of counts.

The bottom row is for some DC signals, including REFLDC, ASDC and POYDC.

You can see that there are so many glitches in the actual time series of the demod signals (actually I picked up the worst time chunk).

It seems that  most of the glitches in REFL11, REFL33 and AS55  coincide.

The typical time scale of the glitches was about 20 msec or so.

Note that the PRMI was locked by REFL33 and AS55 as usual.

I  placed an other Y2-LW-1-2050-UV-45P/AR steering mirror into the beam path of the green beam launching in order to avoid the ~30 degrees use of the 45 degrees mirror. The job is not finished.

Bob, Callum and Daphen noted that our keeping a JDSU HeNe (max power <4mW) is against somebody's SOP.  So I cleared everything that relates to 40m SOS suspending to the bottom shelf of the 2nd cabinet in the cleanroom (the back set of cabinets nearest the flow benches).  The door has a nifty label.  Things that are in there include:

HeNe

HeNe mount

QPD and micrometer mount

microscope and micrometer mount

iris

Al beam block

Magnet gluing fixture

dumbbell gluing fixture

The electronics that we use (HeNe's power supply, 'scope, QPD readout) are still on the roll-y thing under the flow bench.

Surprisingly increasing the gain of the whitening filter didn't improve the noise curve.

It suggests that the ADC noise is not the limiting factor below 10 Hz.

I did some more stuff for the Y arm ALS and updated the noise budget:

After the works, the rms displacement improved a little bit, so it is now at 24 pm in rms.

Though, it turned out that the MFD's ADC is now limiting the noise in a frequency band of 200 mHz - 5 Hz.

So tonight I will increase the gain of the whitening filter to push down the ADC noise more.

(What I did)

 + added the DAC noise and comparator noise based on measurements.

 + redesigned the servo filter shape to suppress the seismic noise below 10 Hz.

 The attached plot below shows the newly designed open loop transfer function together with the old one for a comparison.

UGF is at 120 Hz and the phase margin is about 27 deg.

• FM7 = resonant gain (17)
• FM6 = resonant gain (3)
• FM5 = zero(1) * pole(500)
• FM4 = pole(1) * zero(40.) * 40.
• FM3 = pole(1) * zero(40.) * 40.
• FM2 = pole(0.001)*zero(1)*1000.

JA - MIE - RO!

I have realigned the beam pointing to PMC. The transmitted light increased from 0.74 to 0.83.

The misalignment was mainly in pitch.

 Do we have PSL pos and ang QPD trends?  We should start watching them, because the PMC drifted back down to 0.76 transmission, ~3.5 days after Kiwamu realigned it (his elog is from last Thurs).  Not so awesome.

I walked through the control room just now and found both PMC and MC unlocked.  They're both locked now, but with PMC transmission 0.76, MC transmission ~24,500.

                        One of my goals this week is to get people to make plots with physical units:

That ALS plot would be 5x cooler if the POY11 signal could be in meters instead of counts or cubits.

Here is a new time series plot showing how stably ALS can control the arm length.

In the middle of the plot the cavity length was held at the resonance point for ~ 2 min. and then it passed through the resonance point to show the full shape of the PDH signal.

Apparently the PDH signal is now quieter than before (#6133)

One of my goals in this week is : measurement of the current best ALS noise budget.

Last night I took a new noise spectra of the Y arm ALS, which is shown in the attached figure below.

The displacement of the arm cavity observed from the IR PDH is at 66 pm in rms. In the measurement the arm length was stabilized with the ALS technique.

I realigned the incident beam to PMC at 23:30. The transmitted light went up from 0.78 to 0.83.

Also I decreased the HEPA level down to 20 % for the night time locking.

I searched for a scattering body in the REFL path.

According to the result the REFL path on the AS table is innocent.

The idea of the search method is given as follows:

•   Put a 1/10 ND attenuator at the origin of the REFL path on the AS table.
•   Of course this reduces the signal level by the same factor of 10 in the REFL11_I demod signal.
•   If the scattering body is in the REFL path the up conversion noise will be smaller by a factor of 100 because the scattered light go across the attenuator twice.

Assuming that PRM is interfering with some other optics, I have estimated the optical distance between PRM and an object that interferes with PRM.

The optical distance is estimated to be 9.5 +/- 0.5 m.

If we believe this number the object is most likely outside of the vacuum chambers.

 (The measurement)

1.  Preparation : calibration of the MC2 actuator as a frequency actuator (for more details, see the next section)
2.  Set the interferometer to the single-bounce configuration such that the beam directly is reflected back from PRM
3.  Take spectra of REFL11_I without driving any optics. This spectra tells us how quiet the noise normally is.
4.  Drive MC2_POS at 10 Hz with an amplitude of 10000 counts so that we can see the high frequency up conversion noise
   • The frequency was chosen such that the excitation is out of the local damping bands
   • The amplitude was chosen to be as big as possible until the MC unlocked
   • With this drive, the laser frequency should change by 20 MHz peak-peak at 10 Hz.
5.  Record the noisy spectrum when the MC2_POS was driven.
6.  Drive PRM instead of MC2 at 10 Hz.
   • Adjust the amplitude of the excitation such that the cut-off frequency of the up conversion noise matches with that of the MC2 driven case.
   • The amplitude was found to be 1700 - 2000 counts, this uncertainty is currently limiting the precision of the optical distance estimation.
   • With this amount of the drive, PRM moves by 0.8 um peak-peak at 10Hz.
7. Estimate the optical length based on the amount of the drives for PRM and MC2.
   • Estimate the FSR using the following relation df/FSR = dx/ (lambda/2). => FSR = 17 MHz
   • Since FSR = c/ (2L),  L = c/(2 FSR) = 9.5 m or so

(Calibration of the MC2 actuator)

Transparent- clear plexyglass from tree different sources were measured in 1064 and 532 nm light.

Samples: a, clear Acrylic-GP 0F00  from Ridout Plastics in thickness 0.7" ,  made by  Evonic Ind

                   b, clear cast acrylic from Mc Master Carr in thickness 0.94" , likely  made by Reynolds-Cast

                   c, clear cell cast  plexyglass from Delvie's Plastics - Utah in thickness  0.93" , maker not known

PMC reflected beam was used at 92 mW and 6 mm diameter at incident angle 0-25 degrees.

All tree samples agreed on Transmittance of ~90%, Reflectivity ~3-4% and calculated Adsorption ~6-7%

Transparent Colored Acrylic orange-amber #2422   from www.eplastics.com in 0.12" thickness gave  T 96%,  R 1% and  Ab-calc ~3% in the beam of 92 mW 1064  nm at 6 mm diameter.

Transparent , colored   Light Red #26 thin film filter   policarbonate-polyester   0.002" thick   from Roscolux measured T 81% of 115 mW 1064 nm

Now I changed power meter FieldMate to Ophir and the light source to laser pointer 2.2 mW  ~532 nm  with 1-2 mm beam diameter.

Orange - amber #2422  sample, 0.12" thick,  T 1% ,  R 4%  and  Ab-calculated ~95%, estimated visibility  ~50% It does cut out the green at this low power level.

 Light red #26  sample  T 0.5%  at 2.5 mW of 532 nm . The transparent green is not visible.  The softening point of this sandwiched polycarbonate-polyecter filter is 160C. Estimated VLT of this film ~40%

SUMMERY:

Clear and colored acrylics'  @ 1064 nm  transmittance 90% or higher  regardless of thickness. Softenig point 115 degrees C

Colored acrylic and colored policarbonate film are adsorbing the low power green and they  transmit the 1064nm beam.

Options to consider: a, acrylic laser safety shield liner of  0.125" thick inside of 1" thick clear acrylic  box, OD +5 @1064 and OD +4 @ 532nm,  amber color VLT 27%,  150$/sqft

                                      b, thin metal liner for 1" wall acrylic box, VLT 0%

I wiped both surfaces of the REFL second steering mirror.

However no improvements. The glitches still remain.

(Pic.1 before wiping, Pic.2 after wiping)

 Another possibility is that there is some beam clipping of the REFL beam before it gets to the PD. Then there could be a partial reflection from that creating a spurious interference. Then it would only show the fringe wrapping if you excite the scatterer or the PRM.

Actually awg works fine without any problems when the excitation channels belong to the c1lsc machine.

It seems that the awg doesn't inject signals on the channels of the c1sus machine, for example C1:SUS-BS_LSC_EXC and so on.

 Last night I found that there were many dust particles on the second steering mirror in the REFL path on the AS table.

Looking at it through an IR viewer, I saw the REFL beam hitting one of the biggest dust particles on that mirror.

This dust particle maybe causing the glitches or maybe not.

Anyway because it's always better to have clean mirrors, I will wipe the steering mirror in this evening and check the presence of the glitches again.

I have slightly rotated the lambda/2 plate, which is used for attenuating the REFL beam's power on the AS table

because the plate had been at an unusual angle for investigation of the glitches since last Thursday.

It means the laser power going to the coating thermal noise setup has also changed. Just keep it in mind.

AWG is not working. This needs to be fixed.

I could set the channel and the parameters in the AWGGUI screen, but it never inject signals to the realtime system.

I did a quick test to check a hypothesis that PRM is interfering with some other optics in the single bounce configuration.

I shook all the suspensions (except the MC mirrors) at 3 Hz in POS, PIT and YAW with an amplitude of 1000 counts.

No effects were found in the REFL demod signals.

So it is NOT a fringe effect caused by the other suspended mirrors.