This address for wiki is obsolete. Recently it was switched to https://wiki-40m.ligo.caltech.edu/
Jamie is working on automatic redirection from the old wiki to the new place.

The new one uses albert.einstein authentication.

c1iscex is working as before and the optic is damped.

What I checked

1. I went to the X-end rack. I found the io-chassis was turned off.

2. I shutdown c1iscex, turned off, and turned on everything. Again, we did not have any signal from the ADC into c1scx model.

However, I found that c1x01 indicates healthy ADC signals.
This means that the connection between the IOP and the c1scx model was wrong ==> Simulated Plant

3. Burtrestored X'mas eve snapshot. This restored the gains and matrices as well as C1:SCX-SIM_SWITCH
which switches the input between the real ADCs and simulated plant.

4. The signals came back to c1scx.

There has been no lock of input MC for more than 5days. WTF???

I have fixed a loose mirror of the PMC input and the alignment of the MC2 Yaw.

- The PSL mech-shutter was closed. It has been opened.

- Then, I checked the MC suspensions. Mainly MC2 Yaw has kept drifting. (Fig.1)
In fact, there was no WFS actions during this drift.

Anyway, now MC2 Yaw was aligned and the lock was restored.

- It was very unsatisfactory for me that the PMC alignment kept drifting.
The trend of the PMC REFL and PMC TRANS for a year suggests that:

• Occasional drifts exist since a year ago (or probably since we built this new PMC setup in 2010 Sep)
• The drift has got frequent for the recent four months, and got more for the recent one month.

I went into the PMC setup and tapped several optics in order to find any loose optic.
Immediately I found that the mirror before the AOM was loose. Basically any mild tapping was enough
to misalign the mirror such that the caivty loose the TEM00 mode.

I tightened the retainer set screw of the optic and aligned the PMC again. It looks OK now as I can not
misalign this optic by the tapping anymore. But if it still remains drifting, we need to replace the mount.

I reported the procedure to add slow channels to the FB. I guess you already have done Step.1

http://nodus.ligo.caltech.edu:8080/40m/5991

So why don't you use AS55I and Q for the control of PRMI???

This a kind of self record...

We need an RF setup at POP to extract 22 and 110 MHz components separately.

I am planning to work on this in the daytime on Tuesday.

 As par Kiwamu's request, RF filters for POP22 and POP110 were installed. They are not really nice. We need to replace it with more fancy electronics.
More to come later.

The RF separator installed comprises of the Minicircuits filters cascaded as in the figure below.
This has one input and 4 output ports for 11, 22, 30-60, and 110MHz signal.
As seen in this entry #6167, we have 22 and 110MHz signals together with 11, 44, 66MHz signals.
They may be demodulated via a harmonic characteristic of the mixers. (Remeber mixers are not multipliers.)

 Of course the big concern is the impedance matching for those signals as usual.
The 2nd attachment shows measured impedance of the circuits with all of the ports terminated.
From the complex impedance, we can calculate the reflection coefficient. The 44 and 110MHz
components look correctly matched while the others seems largely reflected.
This certainly is not a nice situation, as the reflection can make the amplifier next to the PD unhappy
(although the reflected power is tiny in our case).

In our case more eminent problem is that the amplitude of the 22MHz signal can vary depending on the cable length by
factor of 10 in amplitude. (c.f. VSWR on the 2nd attachment.)

The transmission to each port was measured. The separation of the signals looks good. But the attenuation of the
targetted signals (i.e. insertion losses) are qulitatively consistent with the impedance. Again these losses are depend
on the cable length.

I'm puzzled why the 11MHz peak can be such high considering 1.7~2 times smaller the modulation depth.

Kiwamu and Koji

The target is to realize DRMI or PRMI + one arm with ALS.

The focus of the night is to achive stable lock of the PRMI (SB resonant) with 3f signals.
Particularly, REFL165 is back now, we are aiming to see if any of the 165 signals is useful.

We made a comparison between  REFL33Q/REFL165Q/AS55Q to find any good source of MICH.
However, none of them showed a reasonable shape of the spectra. They don't have reasonable coherence between them.

Nonetheless, we have tried to lock the IFO with those REFL signals. But any of them were useful to keep the PRMI (SB resonant).
The only kind of stable signal for MICH was AS55Q as we could keep the PRMI locked.

Kiwamu and Koji

We found that the intra-cavity mode of the PRC is not round although it was obvious even with the DARK and REFL port images.
We need to review the mode matching situation.

In order to look at the PRC intra-cavity mode, we reconfigured the POP CCD.

If we look at the beam reflected from the Michelson, the beam is round. However, the PRC intra-cavity mode can never be round
in any resonant conditions. (Pict 1, 2, and 3, for the sideband resonant, carrier resonant conditions and another carrier resonant
one, respactively). Particularly the mode of the carrier resonant case is very unstable and always changing.

By misaligning the PRM, we can compare between the spot directly reflected from the Michelson and the one after additional round trip in the PRC (Pic 4).

They looks round, but it was obvious the secondary reflection is dimmer and larger (Pic 5). The intensity difference corresponds to the factor R_PRM R_MI
(i.e. product of the reflectivities for the PRM and MI). It can be understand if the dimmer spot looks smaller due to the artifact of the CCD. But it is opposite.

This may mean the mode matching is not correct. We are not sure what is not right. This could be just an incorrect incident beam, the curvature error of the PRM,
beam is distortec by the TT mirrors, or some other unknown reasons.

More precise analysis can be done with quantitative analysis of those two spots with Beamscan. This could happen tomorrow.

Did you guys checked if the simplant switch is set to "REAL WORLD" mode?

Edit by KI:

Bingo ! The input signals were bypassed to the simplant. I switched the simplant settings to REAL WORLD and now both end suspensions are working fine.

The mode looks quite terrible in the plot, but in reality it is an illusion of the plot.

The actual TEM00 content in this beam is ~99.7%

mode_coupling.pdf

Based on the above document, you can calculate power coupling between two elliptic gaussian modes.

Give the parameters of one beam as

zRy1 = pi*(2.77e-3)^2 / 1064e-9
z1y = 3.37
zRx1 = pi*(2.47e-3)^2 / 1064e-9
z1x = 4.15

Then, assume a round beam for the other.

zRx2 = zRy2 = zR
z2x = z2y = z0

Then run the optimizer to find the maximum for the quantity |C|^2

|C|^2 max: 0.9967
zR = 20.19
z0 = 3.804

It is quite likely that we touched the Faraday in Nov 2010.

In this entry http://nodus.ligo.caltech.edu:8080/40m/3874 I wrote that I removed the MCT optics in the chamber.
This is the pickoff between the IMC and the Faraday. This causes the beam shift. Therefore, the Faraday had
to be moved.

There were intensive in-chamber activities from Nov to Dec 2010. I am sure that almost everytime we went into
the chamber, we checked the spot position on the MMT mirrors as well as the TT and PZT mirrors.

Does the miscentering of the spots on the MMT mirrors cause the mode matching significantly changed?

And has the temp controller of the green been recovered too? (Push enable button)

From 2PM, Jenne/Den/Koji. Finished at 10:30PM

• General
  • More LCD screens! Wider screens!
    • Allegra - only can handle single head right now, but should prepare for the eventual upgrade of that videocard/whole computer and get 2 monitors.
    • Every workstation should have 2 24" monitors.  We currently have 2 good ones (one on Rossa, one on Pianosa), so we need 6.
  • Remove Control room shelf currently holding OSA 'scopes
  • Adjust both TV shelves so that they're at the same height, ~6" higher than the current left shelf.
    This gives space for stacking the 24" monitors for each computer.
  • Audio system for the signals!!!! Even a crappy one!
         /cvs/cds/ligo/centos5.5/cds/project/gds-2.14.2/Monitors/rockIFO
         /cvs/cds/gds/gds/Monitors/rockIFO
         (really /cvs/cds, not /opt)
    
    
• IOO
  • PZT or Picomotor mounts for PSL/ALS beams
  • ALS on the both arm simultaneously / common/diff ALS scripts
• SUS
  • PRM OPLEV servos are sometimes not stable. (fixed, JCD/DM/KA, 5/2/2012)
  • ETMX oplev - replace 1064nm lens with 632nm lens (KBC037, -100)
• IFO
  • It seems that there is an occasional common-mode power transient in the arm transmissions.
    -> Track down the cause and fix.
  • Fix arm ASS even on CentOS
  • Drift of the green incident axis -> Assess the amount of the drift / replace the mount
  • Calibration of POP22 / AS110
  • PMC/IMC/ARM characterization (loss, finesse, reflectivity, etc)
• CDS
  • Capture OSA signals in CDS (the 'scope TDS1001B has a USB port in the back for connecting to the computer)
  • Transmon (arms) for high and low power
  • POX11 whitening is not toggling the analog whitening???
  • CentOS machines cannot open simulink models properly (get "Bad Link"s everywhere, so you can't do anything useful).
  • Dataviewer and DTT can't connect to framebuilder from CentIOS machines
• Electronics
  • Actuator noise level characterization (coil driver response in V/m & coil driver noise level V/rtHz)
  • Beat box
  • I/Q DFD
  • Improvement of POP22/110/AS110 RF circuits.
• MEDM
  • OL alert in the watch dog screen (this is awesome!) should have small text saying "OL" (done, JCD, 5May2012)
  • Complete 40m overview screen - everything should be clickable with pseudo 3D icons
  • BETTER SUSPENSION SCREEN!!!
  • Script to generate a MEDM tree
  • Resurrect MEDM snapshots
     
  • The LSC screen has some "white" boxes -> investigate and fix them (done, KA, 5/2/2012)
  • Make the LSC control screen (compact) in the vertical arrangement (done, KA, 5/2/2012)
  • The signals of the watch dog screen should go red if any of the WDs are not enabled.
    =>Copy the logic of the signals in LSC screen. (done, KA, 5/2/2012)
  • Remove c1gfd from the cds status screen (done, KA, 5/2/2012)
  • Add "BURT" status indicators on the cds status screen (done, KA, 5/2/2012)
• SCRIPT
  • Locking scripts with integrator triggers / disabling when unlocked
  • Daily diagnosis of the MC spot positions (there must be something already...)
  • Daily/occasional adjustment of the incident axis on the MC
  • Suspension "misalign/restore" script is too wild => make a new script (Done, JCD, 7May2012)
  • IFO_CONFIGURE scripts still do a burt restore, so step the optics.  Need to remove optic alignment from config .snap files, use reg restore script instead.
  • OPLEV/OSEM trending script before the IFO work for diagnosis.
  • Auto-locker for PMC/Arm/etc
• Video
  • If each video screen has a caption, that would be great
  • GUI interface of "videoswitch" Mike!
  • Mouse Jiggler for Zita (called Swinput?)
• Ubuntu
  • burttoday is not aliased in ubuntu. burttoday:      aliased to cd /opt/rtcds/caltech/c1/burt/autoburt/today/
  • ASS doesn't run on Ubuntu!
    ezcawrite: error while loading shared libraries: libca.so: cannot open shared object file: No such file or directory
ezcaswitch: error while loading shared libraries: libca.so: cannot open shared object file: No such file or directory
 

[Jenne/Den/Koji]

We saw some white boxes on the LSC screens.
We found c1iscaux2 is not running.

Once the target was power-cycled, these epics channels are back.
Then c1iscaux2 were burtrestored using the snapshot at 5:07 on 4/16, a day before the power glitch.

[Jenne/Den/Koji]

We locked Xarm/Yarm and manually alignmed ITMX/ITMY/BS/ETMX/ETMY/PZT1/PZT2.

ITMY OPLEV was largely misaligned ==> The beam was centered on the QPD.

----

Then we aligned PRM using SB locking PRMI.

We noticed that OPLEV servo does not work. It made the PRM just noiser.

We went into the PRM table and found that the OPLEV beam was clipped in the vacuum chamber.
We tried to maximize the reflected beam from the window by touching the steering mirrors at the injection side.

Then the reflected beam was introduced to the center of the QPD.

After the alignment, the OPLEV QPD SUM increased to 4000ish from 200ish.
According to the OPLEV trend data, this is a nominal value of the QPD SUM.

Now the OPLEV servo does not go crazy.

 --

BS OPLEV beam was centered on the QPD.

I suspect that it was just unlocked when you had disconnected the cable.

There is not reflection now. It seems that it is now misaligned after the alignment work.

So what you need is "align while scanning PZT -> lock -> align".

No matter how you connect/disconnect, touching the laser may cause the PMC unlocked.

At least, I don't see the PMC reflection on the PD.
This means that the beam towards the PMC is largely misaligned.

If you are not sure what is misaligned, stop touching the table.
Close the shutter of the laser on the laser housing and leave the optics as they are.

OK. Then we should make this number bigger such that the coherence is still completely maintained.
Is this set in the auto locker? Or manually set?

Is this enhancement of spectrum caused by the lock? Or by the actuation?

If this is also seen with approximately same amount of actuation to PRM POS,
this is just a suspension problem.

If this is only seen with the PRM locked, this is somehow related to the opt-mechanical coupling.

I rebooted rossa and the X sever has stalled.

Top tab categolies:

• Summary
• CDS
  • CDS Status
• PEM
  • Seismic 24h trend
  • Accoustic 24h trend
  • Weather/Temp/Barometer/etc 24h trend
• PSL/IOO
  • PSL summary trend / duty ratio
  • IOO summary (MC Health Check/IOO QPD trends / IFO QPD trends / Transmon QPD trends) duty ratio
• SUS
  • Summary
  • OSEM PSD/trend
  • OPLEV PSD/trend
• IFO
  • DC Mon
  • RF ports
  • OMC
• Steve
  • Vacuum
• Misc.

IFO

• DC Monitors
  • Incident beam power trend (24h)
  • AS/REFL/POP/TRX/TRY bean power trend (24h)
  • AS/POP RF beam power trend (24h)
• RF port
  • DARM sensitivity PSD (mean/min/max/reference) for an hour
  • DARM/CARM/PRCL/MICH/SRCL PSD
  • DARM/CARM/PRCL/MICH/SRCL (freq vs Gaussianity)
  • DARM/CARM/PRCL/MICH/SRCL calibration trend
• OMC
  • TBD

ssh -X pianosa

On pianosa

StripTool PSL.strip&
StripTool IOO.strip&
StripTool seismic.strip&

The beam at the dark port was largely clipped.
The arm transmissions (TRX/TRY) were ~0.6 no matter how you try to align.

The PZT1/2 X was scanned and TRX/TRY are now both ~0.9.
This means that the beam was mostly clipped in or after the mode mathing optics.

FPMI contrast is (2.45-0.02)/(2.45+0.02) = 98%
Not so bad although it does not tell anything about clipping before the IFO.

In the next opportunity, we should try to "pin" the beam axis on the arm mirrors using A2L.

1. I am not sure exactly where the clipping was. It means that a small clipping might still be there.

2. I am afraid that the beam is still clipped in the faraday. The beam can be scanned using the steering on the PSL table.

The followings are a kind of daily check. Do this without any notice:

- Align PMC.

- Check MC spot position with the script (where is it located?). Ignore MC2 result as it can be arbitrary set.

- If the MC1/MC3 spots have moved it means that the PSL beam has moved. If the beam has moved, we should have some discussion what we should do.

- If the spot positions are about the same as before, align the MC mirrors. This should be done by nulling the WFS feedback. (Someone should make a simple script for this WFS offloading.)

------------

Then, start locking both arms

 Do that.

Yes. The end PDH servo should be checked more carefully.

The end PDH seems to have insufficient gain at around 100Hz.
The attached is the ALS noise budget calculated with the simulink model for the green locking paper.

The residual error of the end AUX laser (green) is contributing to the final ALS signal (black).
In particular, the residual AUX frequency noise, which is shown as the blue, is contributing to the noise above 100Hz.

In the model I also confirmed that the servo still has a room for improvement.

By having more suppression of the AUX frequency noise, we will be able to increase the ALS servo bandwidth
without increasing the ALS residual RMS by a servo bump. This will give us the improvement of the seismic
noise suppression at 10Hz (i.e. more suppression of red).

Done.

C1:SUS-PRM_OLPIT_GAIN 1.0 -> 0
C1:SUS-PRM_OLYAW_GAIN -0.7 -> 0
 

Interesting. It seems for me that there is a dependence of the noisiness as the beat frequency is scanned.

As you increase (or decrease?) the offset, C1:ALS-BEATY-COARSE_I_IN1 becomes bigger and more crisp.
The resulting out-of-loop stability also seems to be improved as you can see from the crispness of the PDH signal.

Do you find why this happens? Is this because the beat S/N depends on the beat frequency due to the PD noise?

Wow. This is way too short.

You don't need to use Albertoo's arm length as his measurement was done before the upgrade.

Are these correct?

1. It is a nice work.

2. This is not locking, but stabilization of the both arms by ALS.

3. We now have the phase trackers for both arms.

4. There is no coarse (i.e. short) delay line any more.

5. The splitters after the PDs are reducing the RF power to Beat-box.
Actually there are RF monitors on Beat-box for this purpose, but you did not notice them.

6. c1ioo channel list
https://wiki-40m.ligo.caltech.edu/CDS/C1IOO%20channel%20list
has to be updated.

7. Video can be uploaded to Youtube as Mike did at http://nodus.ligo.caltech.edu:8080/40m/6513

I am considering to have 3 to 6 motorized optical mounts at the PSL and end tables for remote beam steering.

Question 1:
Was there any issue on the PI 3-axis PZT on the PSL?
Why was it disabled (even before the PSL upgrade)?


Question 2:
Do we need two mount at a place? Or we do have one instead?

- Comparing the distance of the steering mirrors and that from the steering mirror to the cavity waist, induced shift
is mostly cancelled by angle adjustemnts of a either of the mounts.
i.e. Induced misalignments by the steering mirrors are nearly degenerated.

We need to move two steering mirrors only for the initial installation, but any drift felt by a cavity can be compensated by a single mirror.

Question 3:
Do we like PI-style 2 or 3 axis PZT mount with analog inputs on the HV amp?
Or do we like "Newport Agilis" style controller with USB connection?

Any opinion?

To be fair, this is Kiwamu's idea. And nothing is reasonable before it is confirmed quantitatively.

These aren't so bad. (Look at this entry)

And interestingly the ETM curvatures are closer to ATF measurements than Coastline's measurement. (Look at wiki)

The phase margins looks still too small.

Do You need such high gain at LF? This is not a high finesse cavity so can we sacrifice
some DC gain while gaining more phase around UGFs?

Otherwise, the gain fluctuation should be nicely compensated (i.e. fancy normalization).

This is a good modification. We just need to check how the ALS scripts are affected.

Is this the step response of the single pole low pass???
It should have an exponential decay, shouldn't it? So it should be easier to comprehend the result with a log scale for vertical axis...

I think you need a fast shutter. It is not necessary to be an actual shutter but you can use faster thing
which can shut the light. Like PMC or IMC actuators.

Another point is that you may like to have a witness channel like the MC transmission to subtract other effect.

With your definition of the open loop gain, G=+1 is the condition to have singularity in a closed loop transfer function 1/(1-G).

But this is not the sole criteria of the loop stability.
Basically, the closed loop transfer function should not have "unphysical" pole.
For more about loop instability, you should refer stability criteria in literature such as Nyquist's stability criterion.

Both of the X and Z loops look unstable with the current gain.

Hey, the pages got significantly nicer than before. I will continue to give you comments if I find anything.

So far: There are many 10^-100 in logarithmic plots. Once they are removed, we should be able to see the seismic excitation during these recent earth quakes?

Incidentally, where the script is located? "./" isn't the absolute path description.

From the log, I couldn't understand what has been done.

The procedure we should perform is

1. Dither total 4 dofs of the two mirrors with different frequencies. Some fluctuation of TRY is even visible in dataviewer.
2. The cavity is aligned at the beginning. These 4 peaks in TRY in DTT is small or invisible. Some 2nd harmonics are visible.
3. Misalign one of the dofs. Some peaks get bigger.
4. Correspoding lockin output becomes bigger.

Then you can start measuring the sensing matrix. At which part did the attempt fail?

That's a good point, but I suspect that you end up with the in-phase (0deg) as the response of the IFO is immediate compared with the dithering frequency
as long as the whitening/dewhitening are properly compensated in the digital realm.

I unlocked the door on Tuesday in order to move the red cart.
After that I confirmed that the door was locked.

You mean 5000?

I used the LED illuminations at ETMX and BS yesterday for a tour.
I am afraid that I left them on.

[Koji Rana]

MC Autolocker was updated. (i.e. mcup and mcdown were updated)

mcup:

• Turn on the MCL input and output switches
• Change the MCL gain from 0 to -300 with nominal ramp time of 5sec
• Turn on FM2, FM5, MF7 after a sleep of 5sec. Note: FM1 FM8 FM9 are always on.
• Set the offset of 42 counts
• Turn on the offset

# Turn on MCL servo loop
echo mcup: Turning on MCL servo loop...
date
ezcaswitch C1:SUS-MC2_MCL INPUT OUTPUT ON
ezcawrite C1:SUS-MC2_MCL_GAIN -300
sleep 5
ezcaswitch C1:SUS-MC2_MCL FM2 FM5 FM7 ON
# Offset to take off the ADC offset of MC_F
ezcawrite C1:SUS-MC2_MCL_OFFSET 42
ezcaswitch C1:SUS-MC2_MCL OFFSET ON


This offset of 42 count is applied in order to compensate the ADC offset of MC_F channel.
The MCL servo squishes the MC_F signal. i.e. The DC component of MC_F goes to zero.
However, if the ADC of MC_F has an offset, the actual analog MC_F signal, which is fed to FSS BOX,
still keep some offset. This analog offset causes deviation from the operating point of the FSS (i.e. 5V).

mcdown:

• Basically the revese process of mcup.
• This script keeps FM1 FM8 FM9 turned on.

# Turn off MCL servo loop
echo mcdown: Turning off MCL servo loop...
date
ezcawrite C1:SUS-MC2_MCL_GAIN 0
ezcaswitch C1:SUS-MC2_MCL INPUT OUTPUT OFFSET FMALL OFF FM1 FM8 FM9 ON
# Remove Offset to take off the ADC offset of MC_F
ezcawrite C1:SUS-MC2_MCL_OFFSET 0

[Koji Rana]

The FSS Slow DC servo was turned off.

As MCL stabilizes the MC_F (Fast PZT), we no longer need to use the laser temp to do so.

In other word, if you like to turn off the MCL servo for some reason, we need to turn it on in order to keep the MC locked.

as usual.