40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 101 of 344  Not logged in ELOG logo
IDup Date Author Type Category Subject
  5037   Tue Jul 26 11:38:45 2011 steveUpdateSUSETMY bias checked

 

 I test drove ETMY biases.

PITCH  worked well in slow and fast modes. Slow drive was from the IFO alignment screen C1:SUS-ETMY_PIT_COM and

the fast one from C1:SUS-ETMY_ASCPIT_OFFSET

YAW did not.  It was always diagonal. It was  specially bad with the fast drive. I compared them with ETMX. ETMX yaw is diagonal a little bit too.

The OPLEV return spots on the qpd ETMX and ETMY are big 5-6 mm diameter. The ETMY spot has weird geometry to qpd.

  5038   Tue Jul 26 21:11:40 2011 haixingSummaryElectronicsAA filter tolerance analysis

Given this new setup, we realized that the previous tolerance analysis is incorrect. Because the uncertainty in the capacitance value
does not affect the common mode rejection, as two paths share the same capacitor. Now only the imbalance of two resistors is relevant.
The error propagation formula goes as follows:


We require that the common-mode rejection error at low frequency up to 8kHz, namely
with , one can easily find out that the corner frequency needs to be around 24kHz.


 

  5039   Wed Jul 27 01:57:28 2011 SonaliUpdateGreen LockingWeekly Summary

1. I have used the PMC  trans beam in my set-up as the required PSL beam.

2. I have superposed the ETMX-Fibre output with the PSL beam on the PSL table.

3. I have used suitable beam splitters and lens to match the power and the  sizes of the overlapping beams and have aligned them to the optimum.

4. A lens having f=7.6 cms is used to focus the beam into the PD.

5. Initially, I used the broadband 1611 NewFocus PD to find the IR beat signal by scanning the oven temperature. (using the digital sitemap controls.)

6. I checked the previous elog entries by Suresh and Koji on the green beat signal they had worked on and used their data to get an idea of the temperature range of the oven where I could obtain a beat.

7. I obtained peaks at three different temperatures as had been noted previously and set the temperature so that I am now sitting in the middle stable regime.

8. Then I switched to the 1811 100 MHz PD as it has a larger gain. It has a saturation power of 100 microWatts. The input power at the PD is measured to be 80 microWatts.

9. I was having trouble getting a clean peak due to presence of many harmonics as seen on the spectrum analyser. This happened because there was too much power incident on the PD which led to arising of non-linearity giving rise to harmonics.

10.To reduce the power entering the PD, I put in a ND 1.0 Filter just before the beam enters the PD and obtained a clean signal.

11. I will use  the frequency counter tomorrow to check the resonant frequency and try to connect the output to acquire a digital signal.

12. Otherwise I will proceed to build a Mixer Frequency Discriminator.

13. After the feed-back loop is completed, I will proceed to compare the frequency-noises of the green-beat lock and the IR-beat lock.

  5040   Wed Jul 27 01:58:23 2011 kiwamuUpdateLSClocking status

Through some locking exercise I found that several things are degrading.

Remember the interferometer is like a cat, so we have to feed and take care of her everyday. (Otherwise the cat will be dead !)

 

Beam axis:

 I guess that the beam axis has changed a lot to the horizontal direction.
The beam spots on the REFL and AS camera looked off-centered by a size of the spot.
The beam axis has to be well-aligned before the vent.

 

Locking of the Arms :

 didn't lock at all. It could be a problem of the demodulation phase on AS55.
Also the TRY camera looked pretty much off-centered. The spot is already getting out from the field of view.
We have to fix this issue, otherwise we cannot align the beam axis.
 
 

Locking of PRM :

 Sort of okay, I was able to lock both MICH and PRCL although I had to flip the sign of the MICH control gain due to the demod-phase change.
The suspensions don't look healthy. The beam spots on the REFL and AS camera move a lot even without any length feedback.
It means some of the suspensions are shaky.
  5041   Wed Jul 27 08:59:10 2011 SureshUpdateLSClocking status

 I had to realign PSL beam into the MC in order to reobtain the MC lock.  We lost lock at sometime around 8:30 AM on Tuesday.  See attached trend data for MC_RFPD_DCMON. 

The is the second time this week that I had to do this when we were unable to obtain the MC lock.  On both occassions the zig-zag at the end of the PSL table was tweaked to minimise the MC_RFPD_DCMON.

MC_RFPD_DCMon.png

 We have been using the MC as a Beam Axis Reference.  And therefore we are adjusting the PSL beam to maximise coupling into MC.  However if MC's beam axis has shifted, then would it not be best to use the pzt's to re-obtain coupling into the arm cavities? 

Quote from #5040

Beam axis:

 I guess that the beam axis has changed a lot to the horizontal direction.
The beam spots on the REFL and AS camera looked off-centered by a size of the spot.
The beam axis has to be well-aligned before the vent.

  5042   Wed Jul 27 10:04:29 2011 SureshUpdateIOOWFS transfer function measurements

This is part of the WFS activity.  So far I have completed the following tasks:

1)  I fixed the MEDM screens up to a point where they can be used for locking.  There are still some buttons which invoke non-existing screens and some blank fields.  But the basic filter banks and input  and output matrices are fixed.

2) I copied all the old filter banks into the new screens both in the WFS head and in the WFS Master, where the servo filters are located.  The I and Q filter banks in the WFS heads have been switched on.

3) I <=> Q phase settings in the WFS head for each quadrant:  We have assumed that the I and Q are orthogonal so D=90 for all cases.  I set the R phase to minimise the signal in all the Q lines.  So the signal is largely in the I phase.  I used Sine Response feature in DTT while supplying an excitation signal to MC2_ASCPIT_EXC.  At times I used the YAW instead of PIT if I did not get enough coherence.  This was set manually by watching the Q phase signal and minimising that by adjusting the R angle.  It was in general possible to get this correct to a deg.   There are several old scripts to do this in the MC/WFS but they do not work since most of them are based on the ezlockin or ezcademod functions.    I will try to fix the ezWFS1phase and ezWFS2phase scripts to automate this.  Some channel names have to be changed in these.

4) I measured the transfer function between the mirror motions [(MC1, MC2, MC3) x (PIT, YAW)] and the sensor DoF [(WFS1, WFS2) x (PIT, YAW)].  The measurements are reported below.  The plan is to invert this matrix and use it as the Out_Matrix.

WFS_TF_Phase_Sheet1.png

I list here the various steps I took in making this measurement.

a) Set the DC offsets on the individual quadrants to zero using an old script (which I updated with the new channel names).  The script is called McWFS_dc_offsets and is located in the $scripts$/MC/WFS directory.   Note that before doing this the PSL shutter was closed.  This script sets a basic EPICS parameter called AOFF for each channel.  These are listed in cvs/cds/caltech/target/c1iool0 .

b) Then the PSL beam into the MC was steered to optimise coupling into MC (described in my earlier post today).  This is because we use the input beam as a reference while setting up the WFS.

c) Unlock the MC and center the directly reflected beam from the MC on the WFS.  We use the DC monitors on the C1IOO_WFS_QPD.adl screen to center the spot on the WFS head. 

d) Then used the WFSoffsets script to set the offsets in the I and Q filter banks to zero.  This script uses the ezcaservo to look at the OUT16 channels and zeroes them by setting an appropriate offset.  I took care to switch off all slow filters in the I and Q filter banks before this operation was carried out .  Only the 60Hz comb filter was on.

e) Opened the PSL shutter and relocked the MC

f) Then I measured the transfer co-efs by oscillating the optic (exciting a specific degree of freedom) and observing the response in the WFS sensor degrees of freedom.   These are tabulated above.

Next

   I plan to use this matrix and prepare the Output matix and then close the WFS servo loops. 

 

 

  5043   Wed Jul 27 10:10:12 2011 steveUpdatePSLlocking status

 80 days: PMC is drifting

  5044   Wed Jul 27 12:19:19 2011 NicoleSummarySUSWeekly Summary

Since last week, I've been working on building the photosensor head and have been making adjustments to my photosensor circuit box.

Changes to photosensor circuit (for box):

1) Last week, I was reading in the two signals from the two heads through a single input. Now there are two separate inputs for the two separate photosensors

2)During one of my many voltage regulator replacements, I apparently used a 7915 voltage regulator instead of a 7805 (thanks, Koji, for pointing that out! I never would have caught that mistake X___X)

3)I was powering my 5V voltage regulator with 10V...Now I'm using 15 V (now I only need 1 power supply and 3 voltage input plugs)

I have also began assembling my first photosensor head. Here is what I have so far:

sensorhead.JPG

 

Here is what needs to be done still for the photosensor head

I need to find four Teflon washers and nuts to rigidly attach the isolated PCB (PCB, Teflon sheet combination) to the box. I already have the plastic screws in (I want to use plastic and Teflon for electrical isolation purposes, so as to not short my circuit).

I need to attach the sheath of my signal cable to the box of the photosensor head for noise reduction (plan: drill screw into photosensor head box to wrap sheath wires around)

I need to attach the D-sub to the other end of my signal cable so that it can connect to the circuit box. So far, I only have the D-sub to connect the cable to my photosensor head

Yesterday, Suresh helped to walk me through the photosensor box circuit so that I now understand what voltages to expect for my circuit box trouble-shooting. After this lesson, we figured out that the problem with my photosensor box was that the two op-amps were saturated (so I fixed the feedback!). After replacing the resistor, I got the LED to light up! I still had problems reading the voltage signals from the photodiodes. I was reading 13.5V from the op amp output, but Koji explained to me that this meant that I was too close to saturation (the photodiodes were perhaps producing too much photocurrent, bringing the output close to saturation). I switched the 150 K resistor in the feedback loop to a 3.4K resistor and have thus successfully gotten displacement-dependent voltage outputs (i.e. the voltage output fluctuates as I move my hand closer and farther from the photosensor head). 

Now that I have a successful circuit to power and read outputs from one photosensor, I can begin working on the other half of the circuit to power the other photosensor! 

sensorcircuit.JPG

  5045   Wed Jul 27 12:31:47 2011 Manuel, IshwitaSummaryPEMWeekly summary

We kept reading about digital filtering

We tested the seismometer last friday

Jan came and tested again the seismometer last monday

We wrote a simulation of the stacks transfer functions, and of the distance between the mirrors.

 

  5046   Wed Jul 27 15:18:50 2011 kiwamuSummaryGeneralschedule

The vent will start from 1 st of August ! !

  5047   Wed Jul 27 15:38:01 2011 steveUpdateVACbeam traps for vacuum

We have cleaned, baked, rga scaned traps for vacuum. Thorlabs LB1 on 1" OD ss posts and forks. The effective surface area is 43 x 18 mm of stacked razors.

Seven pieces are mounted on New Focus #9962  1" OD SS vented-  pedestrals to 5.5" center height and 5 pieces to 4.875"

  5048   Wed Jul 27 15:42:41 2011 kiwamuSummaryGeneralmitues of 40m meeting : Task list

Quote:

The vent will start from 1 st of August ! 

 ++++ Task List for the vent preparation ++++

  + Preparation of beam dumps (Jamie / Steve)

  + Health check of shadow sensor and measurement of the cross-coupling  (Steve)

  + Measurement of the arm Lengths and estimation of the required precision (Kiwamu)

  + Alignment of the Y green beam (Suresh)

  + Alignment of the incident beam axis (Jenne)

  + Measurement of the MC spot positions  (Suresh)

  + Loss measurement of the arm cavities (Kiwamu / volunteers)

 

 ++++ Task List for the post-vent activity ++++

  + 3f RFPDs (Koji / Rana)

  + EOM resonant circuit (Kiwamu)  

  + Sophistication of the LSC model (Yoichi)

  + DRMI commissioning (Keiko / Anamaria)

 

  5049   Wed Jul 27 15:49:13 2011 jamieConfigurationCDSdataviewer now working on pianosa

Not exactly sure what the problem was, but I updated to the head of the SVN and rebuilt and it seems to be working fine now.

  5050   Wed Jul 27 15:49:56 2011 steveUpdateSAFETYManuel receives safety training

Our surf student Manuel Marchiò received 40m specific safety training today.

  5051   Thu Jul 28 02:33:04 2011 JenneUpdateLockingYarm flashing, but not yet locked

Because I'm too lazy to write a cohenrent elog right now, here's my notes that I wrote while working tonight:

Elog notes, 27July2011

Aligned Xarm, just to check on it.  Had to flip sign of TRX in DCPD filter bank (to gain of -1) to make the signal positive.

Restored Yarm, see some slight flashing, but no lock yet.
Adjusted phase rotation of AS55 from 56.5deg to 60deg, just by-eye trying to maximize AS55I, my arm error signal. AS55I goes from ~ -40 to +60 counts

Tried fitzing with Yarm gain, flipping sign, incr gain. No real change in signals, or flashing.


Incr. ETMY oplev gains to -0.4 from -0.2
Engaged ELP35's on Pit and Yaw, to be more similar to other optics.  However, right now all of the optics have different things in their filter banks.  Why??

Arm is flashing pretty reliably now, but still not locking.  The trigger threshold is always satisfied, so that's not it.

  5052   Thu Jul 28 13:51:00 2011 SonaliUpdateGreen LockingZHL-32A-S.

Initially I was using RFPD-1611to get the IR beat frequency. Its gain was not very high, so I was getting a very low signal of power -37 dBm.

I used ZHL-32A-S with a gain of 25 dBm to amplify it before feeding it into the spectrum analyser.

I connected the ground of the amplifier circuit to the red of the power supply, which blew the amplifier.

I learnt that there is a small tab indicating the ground side of the BNC to banana connectors which I should have noticed.

I learnt to plug in the side with th little tab on it into the ground of the power supply. (Learnt it the hard way I guess!!)

 

 

  5053   Thu Jul 28 16:00:28 2011 kiwamuUpdateComputer Scripts / Programsanother offset script : offset2

A new offset-zeroing script has been developed and it is ready to run.

 

 The motivation is to replace the old zeroing script called offset by a better one because this old script somehow failed to revert the gain settings on a given filter bank.

The new script, named offset2, does the same job, but uses tdsavg instead of using ezcaservo. So it doesn't screw up the gain settings.

Additionally the structure of the script is much simpler than the old offset script, and fewer ezca-functions.

I will modify some scripts which use the old offset script so that all the offset-zeroing is done by offset2.

 

P.S.

Useful scripts are listed on the 40m wiki

http://blue.ligo-wa.caltech.edu:8000/40m/Computers_and_Scripts/All_Scripts

  5054   Thu Jul 28 16:10:34 2011 kiwamuUpdateLSCBoth arm locked

[Nicole / Jamie / Rana / Kiwamu]

  The X arm and Y arm have been locked.

The settings for the locking were stored on the usual IFO_CONFIGURE scripts, so anybody can lock the arms.

In addition to that Nicole, Jamie and Rana re-centered the beam spot on the ETMY_TRANS camera and the TRY PD.

The next step is to activate the C1ASS servo and align the both arms and beam axis.

 

 

Xarm locking notes:

* Changed TRX gain from -1 to -0.02. Without this 50x reduction the arm power was not normalized.

* Had to fix trigger matrix to use TRX for XARM and TRY for YARM. Before it was crazy and senseless.

* Lots of PZT alignment. It was off by lots.

* Yarm trans beam was clipping on the steering mirrors. Re-aligned. Needs to be iterated again. Be careful when bumping around the ETMY table.

* YARM gain was set to -2 instead of -0.2. Because the gain was too high the alignment didn't work right.

ALWAYS HAVE an OPEN DATAVIEWER with the standard ARM channels going when doing ANY INTERFEROMETER WORK.

THIS IS THE LAW.

  5055   Thu Jul 28 16:26:42 2011 steveUpdateSUSITMX, ITMY & ETMY OSEM gains adjusted

 

OSEM damping gains were adjusted by observing  real time dataviewer to get Q of 5

OSEMs were kicked up one by one with 200 counts  ~1sec. The error signal was optimized to get 1/2 of exitation amplitude at the 5th sinusoid wave.

C1: SUS-ITMX_SUSPOS_N1 gain   111      ->        65,             PIT        7.2      ->    8,           YAW        12      ->     6,          SIDE     280

                  ITMY                                      277       ->     120,                        19.2     ->     7,                             24     ->     19,                        420    ->      470

                  ETMY                                       10        ->       32,                          20      ->     3,                             20     ->     10,                          50

                  ETMX                                       22        ->      25,                             3,                                                3,                                              -170  

ETMX having problems:  1, YAW can not be excited

                                             2, SIDE has no error signal in dataviewer. Sensing voltage on MEDM screen 0.142V

 

                      

 

  5056   Thu Jul 28 17:04:04 2011 NicoleUpdateSUSPhotosensor Head Calibration Curve

Here is the calibration curve (displacement versus voltage output) for the photosensor head that I made with the S5971 photodiodes and L9337 LEDs. This was made using a regular mirror. The linear region appears to be between 0.4 and 0.75cm. I will need to arrange the photosensor head so it measures displacements in the linear region of this plot. This plot was made using a 287 ohm resistor.

187K_resistor.jpg

  5057   Thu Jul 28 19:49:12 2011 SonaliUpdatePSLPMC trans beam aligned.

Kiwamu and I aligned the PMC transmitted beam the incident beam going to PMC today.

I learnt how to lock the PMC using the digital controls.

  5058   Thu Jul 28 21:52:40 2011 ranaUpdateComputersanother attempt to use pianosa
  1. Pianosa doesn't cache the SVN pwds so you need to re-enter at each SVN up or commit. This is different from the rest of our workstations. We need to determine what behavior we want.
  2. Tried to use the netGPIB scripts:

pianosa:gpib 0> ./readSR785.csh rb2
rb2
netgpibdata.py: Command not found.

  5059   Fri Jul 29 12:25:54 2011 Ishwita, ManuelUpdatePEMSTS-2 seismometer box

The 'Bacardi' STS-2 seismometer was tested with the "purple" breakout box and it was found out that all the three axes gave a voltage of 11 V (as shown on the screen of the oscilloscope) before pressing the auto-zero button and after pressing it the voltage shown was 6 V. We tried again the blue box and it was working perfectly after pushing the auto zero button (the auto zero took a few seconds). The power of the purple box is still on, we will wait a few hours, to see if something changes.

  5060   Fri Jul 29 12:39:26 2011 jamieUpdateCDSc1iscex mysteriously crashed

c1iscex was behaving very strangely this morning.  Steve earlier reported that he was having trouble pulling up some channels from the c1scx model.  I went to investigate and noticed that indeed some channels were not responding.

While I was in the middle of poking around, c1iscex stopped responding altogether, and became completely unresponsive.  I walked down there and did a hard reset.  Once it rebooted, and I did a burt restore from early this morning, everything appeared to be working again.

The fact that problems were showing up before the machine crashed worries me.  I'll try to investigate more this afternoon.

  5061   Fri Jul 29 16:04:51 2011 steveUpdateSUSETMX, PRM & SRM OSEM gains set

Jamei fixed the computer. Now I had a healthier ETMX with SIDE signal that allowed me to set gains to get Q of 5

The Y arm restore locked the arm at TRY -out 2.4V,    the X arm still did not lock or align to lock. It has some fringes.

ETMX  POS gain   22  -> 17,              PIT  3  ->  1,                    YAW  3,                     SIDE     -170    ->    -110

PRM                        50  ->  30,                     1,                                       2,                                       50

SRM                        55  ->  20,                    2.4  ->  1.5,                      4.8  ->  2,                          140   ->    100

Now all SUS OSEM gains are set

  5062   Fri Jul 29 16:25:06 2011 kiwamuUpdateASCbeam axis and Y arm aligned

Last night I aligned the incident beam axis and the Yarm by touching the PZT mirrors and the suspensions.

I didn't estimate how good they were aligned, but I guess the Y arm is now ready for the Y green light.

 Next : Y green alignment and the MC spots measurement / alignment.

 

 ++ Motivation ++

Prior to the coming vent we want to have the Y arm, incident beam axis and Y green light aligned so that we can align some necessary optics in the chamber.

Also alignment of the incident beam will allow us to re-position the incident beam alignment monitor (i.e. IPPOS and IPANG).

Our plan was to first align the Y arm using the ASS system and then align the Y green light to the Y arm.

 

++ what I failed ++

First I was trying to measure the spot positions on the MC mirrors to make me sure the beam axis has/hasn't changed.

Also I was going to align the MC suspensions to have nice spot position on each suspension using the MCASS system

because this will help us checking the beam clearance in the Faraday and perhaps re-positioning of the Faraday during the coming vent.

But essentially I failed and eventually gave up because MCASS didn't work. It seems that MCASS needs some modifications in the scripts.

Then, to make me feel better I moved on to the Y arm and beam axis alignment.

 

++ what I did ++

I tried using C1ASS to align the incident beam and suspensions on the Y arm, but it didn't work.

However the drive signals from ASS and its demodulated signals looked fine. Only the feedback did not work correctly.

Every time I enabled the feedback paths, the arm just lost the lock. Something is wrong in the feedback paths.

Then I started to align the cavity by my hands while looking at the demodulated signal from each LOCKIN module.

I aligned the things until each demodulated signal fluctuates around zero.

At the end the beam spots on the ETMY and ITMY camera looked well-aligned and the transmitted light became larger by a factor of 2ish.

  5063   Fri Jul 29 18:43:02 2011 Manuel, IshwitaUpdatePEMplugging seismometers to ADC

[Manuel, Ishwita, Jenne, Jamie]

We changed the C1PEM model and the names of the C1:PEM channels.

We reinstalled the blue breakout box, since the purple one still didn't work.

So, now the AA board channels are connected as follows...

C1 = C1:PEM-SEIS_GUR1_X

C2 = C1:PEM-SEIS_GUR1_Y

C3 = C1:PEM-SEIS_GUR1_Z

C4 = C1:PEM-SEIS_GUR2_X

C5 = C1:PEM-SEIS_GUR2_Y

C6 = C1:PEM-SEIS_GUR2_Z

C7 = C1:PEM-SEIS_STS_1_X

C8 = C1:PEM-SEIS_STS_1_Y

C9 = C1:PEM-SEIS_STS_1_Z

C11 = C1:PEM-SEIS_STS_2_X

C12 = C1:PEM-SEIS_STS_2_Y

C13 = C1:PEM-SEIS_STS_2_Z

C14 = C1:PEM-SEIS_STS_3_X

C15 = C1:PEM-SEIS_STS_3_Y

C16 = C1:PEM-SEIS_STS_3_Z

C17 = C1:PEM-ACC_MC1_X

C18 = C1:PEM-ACC_MC1_Y

C19 = C1:PEM-ACC_MC1_Z

C20 = C1:PEM-ACC_MC2_X

C21 = C1:PEM-ACC_MC2_Y

C22 = C1:PEM-ACC_MC2_Z

Although the channels for all 3 STS-2 seismometers are made but only one is installed. So only Channels C1 to C9 are now in operation...

We checked the data from the plugged channels with the Dataviewer. We could see the peak whenever someone jumped in the lab. Even Kiwamu jumped and saw his signal.

  5064   Sat Jul 30 00:33:33 2011 KojiUpdatePSLABSL Laser crystal temp left largely excited & left unattended for more than 3hours

I found that the ref cav trans CCD view was blinking with 30-50 fringe amplitudes. This meant the laser freq was swinging ~50GHz.

I checked the ABSL laser and the SG out of a lock-in amplifier was connected to the slow input.

This was shaking the laser temp from 29degC to 46degC. This was the cause of the fringe swinging.
This big excitation changing the output power too as the temp was changed across it mode-hop region.

I have disconnected the excitation from the laser no matter how useful experiments were took place as there was no e-log entry about this.

I need the explanations

1. Why our precious laser is exposed to such a large swing of temperature?

2. Why the excitation is left like that without any attendance?

3. Why there was no elogging about this activity?

  5065   Sat Jul 30 02:47:43 2011 ranaUpdatePSLABSL Laser crystal temp left largely excited & left unattended for more than 3hours

 Hmm. Should have only been +/- 1 GHz. Some setting got changed apparently...

This is a part of the RefCav temperature measurement setup. You'll get an elog from Jenny very soon.

  5066   Sat Jul 30 05:11:45 2011 SureshUpdateGreen LockingY- end table clean-up

The optics on the Y-end table which required to be moved have been repositioned.  Please see the attached pic for details.

The green beam is not yet aligned to the cavity. That is my next task.

Y-end_table_work.png

  5067   Sat Jul 30 06:24:06 2011 kiwamuUpdateASCY arm ASS fixed

The servos of C1ASS for the Y arm and the beam axis alignments were fixed.

Now we can correctly run the Y arm ASS from the C1IFO_CONFIGURE window as usual.

The sign of some control gains had been flipped for some reasons, so I changed them to the correct signs.

 

Next : Health-check for the X arm ASS, the loss measurements.

Quote from #5062

I tried using C1ASS to align the incident beam and suspensions on the Y arm, but it didn't work.

 

  5068   Sat Jul 30 07:07:28 2011 kiwamuUpdateASCMCASS status

Since we will measure (and hopefully adjust) the spot positions on the MC suspensions prior to the vent, MCASS is necessary for it.

 

#######################

Here is the MCASS status so far:

  + Valera worked on MCASS on the last February, and basically no progress after he left.

  + The MCASS model had been completed in C1IOO.mdl.

  + He made some useful scripts, including mcassup, mcassOn/Off, senseMCdecenter, senseMCmirrro and senseMCdofs.

       Summary of those scripts can be found in his entry #4355.

  + We haven't closed the MCASS loops.

  + The control filters are still blank.

  + We haven't put any elements on the input and output matrices.

  + Some parameters for the dithering oscillators and demodulation systems were properly set.

     So we can get the demodulated signals by simply running mcassUp and mcassOn. (This essentially corresponds to the A2L measurement.)

  + The PIT motions are driven at 10, 11 and 12 Hz for MC1, 2 and 3 respectively. For YAW, the frequencies were chosen to be 11.5, 12.5 and 13.5 Hz.

  + Some medm windows were prepared but not as refined as that of ASS.

  + Valera performed a measurement of the spot positions by using MCASS. The results are summarized in #4660.

  + We made an estimation about the beam clearance on the Faraday based on the measured spot positions (#4674)

 

#########################

So, it seems we should be able to at least measure the spot positions soon by using his scripts.

  5069   Sat Jul 30 10:01:35 2011 JennyUpdatePSLPSL table work

I've been working on the PSL table to put together a setup so that I can measure the reference cavity's response to a temperature step increase at the can surrounding it. My first step was to mode match the beam coming from the AP table to the cavity.

I implemented my mode matching solution. I ended up using a different one from the one I last elogged about. Here is the solution I used:

Two lenses: f = 1016.7.6 mm at -0.96 m and f = 687.5 mm at -0.658 m. (I set my origin at the polarizing beam splitter--the spot where I want my beam to match the beam coming from the PMC, so all waists are behind that point). Below is what it should look like.

modematchpic.pngmodematchinfo.png

What I did on the table:

  • Before placing lenses I aligned the beam and added a 1/2-wave plate between the two polarizing beam splitters to change the polarization of the beam from S to P.
  • I aligned the beam so that it reflected off of the cavity opening (monitoring the reflected power with a photodetector connected to an oscilloscope and tweaking the alignment to maximize the reflected signal). 
  • I then placed the lenses at -0.93 and -0.64 mm because the exact spots were blocked by optics being used in another setup.
  • I reasoned that since the fitting for the initial waist is so uncertain, the lens position being off by a few cm will not produce the dominating source of error. I am now driving the laser frequency using a lock-in as a function generator to drive the laser temperature at ~1 Hz. I'm then monitoring the power transmitted by the reference cavity with a camera connected to a TV monitor. I will use this setup to improve my mode matching.

Here's a picture of the PSL table with the lenses and mirror I added. The beam is redirected by a mirror and then a polarizing beam splitter. Past the beam splitter is another lens (f=286.5 mm), which was already in place from the mode matching of the beam from the PMC to the reference cavity.

modematch_setup_pic.png

Here is a block diagram of my intended experimental setup:

LIGO_block_diagram.png

I am going to try to lock the laser to the cavity given my preliminary mode matching and then go back and improve it later. My next step is to find a frequency range for dithering the voltage sent to the PZT. To do this I will:

  • Measure the transfer function (amplitude response) of the PZT using a photodiode. The power outputted by the laser varies with driving frequency.
  • Find a frequency region in which the amplitude response is low.
  5070   Sat Jul 30 10:03:32 2011 JennyUpdateComputer Scripts / ProgramsMode matching

I ended up having to switch to a different mode-matching solution, because I was unable to find the f = 572.7 mm lens. See my next elog entry (5069).

  5071   Sat Jul 30 19:06:25 2011 ryan, ranaUpdatePSLReturn of the PSL temperature box

Quote:

The PSL temperature box has returned to service, with some circuit modifications. The 1k resistors on all the temp. sensor inputs (R3, R4, R7, R8, R12, R12) were changed to 0 Ohm. Also, the 10k resistors R26, R28, R29, and R30 were changed to 10.2k metal film. The DCC document will be updated shortly. There is now an offset in the MINCOMEAS channel compared to the others, which will be corrected in the morning after looking at the overnight trend.

 Forgot to do this in May. Have just changed the values in the psl.db file now as well as updating them live via Probe.

To make the appropriate change, I took the measured offset (5.31 deg) and added 2x this to the EGUF and EGUL field for the MINCO_MEAS channel. (see instructions here)

Committed the .db file to the SVN.

attached plot shows 8 days of trend with 5.31 degC added to the black trace using the XMGRACE Data Set Transformations

  5072   Sat Jul 30 20:41:50 2011 ranaUpdatePSLRefCav Stabilization back on

 Untitled.png

I turned the RefCav heater and servo back on a couple days ago. At first it was stabilizing again at a low setpoint, but in reality the right temperature (~40 C). After fixing the in-loop signal offsets, the setpoint now correctly reflects the actual temperature.

Jenny is going to calibrate the sensors using some kind of dunking cannister next week.

  5073   Sat Jul 30 21:04:23 2011 kiwamuUpdateASCY arm ASS fixed

The X arm ASS was also fixed. So both X and Y arm ASS are now back to normal.

Now we can align the arms any time from the buttons on the C1IFO_CONFIGURE window.

 

(notes)

The reason why the servo didn't work was that the sign of some control gains had been flipped.

This was exactly the same situation as that in the Y arm ASS (#5067).

Quote from #5067

The servos of C1ASS for the Y arm and the beam axis alignments were fixed.

  5074   Sun Jul 31 00:05:52 2011 kiwamuUpdateLSCscript for loss measurement : modified

I modified the script armloss so that the channel names in the script are properly adopted to the new CDS.

Additionally I disabled the ETMX(Y)_tickle command in the script.

The tickle command puts some offsets on the LSC signal to let the arms pass through a fringe until it gets locked, but apparently we don't need it because the arms are loud enough.

A brief check showed that the script ran fine.

I will measure the loss on the X and Y arm cavity tomorrow.

Quote from #5067

Next : Health-check for the X arm ASS, the loss measurements.

 

  5075   Sun Jul 31 00:37:57 2011 kiwamuUpdatePSLRe : PSL table work

I think you made a simple mistake in your diagram -- the mixer must be replaced by a summer circuit. Otherwise you cannot do the PDH lock.

Quote from #5069

LIGO_block_diagram.png

  5076   Sun Jul 31 17:28:34 2011 kiwamuSummaryLSCTolerance of Arm length = 2 cm

 Required arm length = 37.7974 +/- 0.02 [m]

This is a preliminary result of the estimation of the Arm length tolerance.

This number was obtained from a simulation based on Optickle.
Note that the simulation was done by considering misplacements in only the arm lengths while keeping PRCL, SRCL and MICH at the ideal lengths.
Therefore the tolerance will be somewhat tighter if misplacements in the central part are taken into account.

Next : check 3f signals, and include misplacements in PRCL, SRCL and MICH.



(Background)
We will re-position the ETMY/Y suspensions to adjust the arm lenghts during the coming vent.
To get a reasonable sensing matrix for LSC, the arm length must be adjisted within a certain precision.
So we need to know the tolerance of the arm lengths.
 

(How to estimate)
Optickle, a frequency domiain interferomtere simulator, is used to model the response of the 40m interferometer.
I buit a 40m model in Optickle, and in this model every optical distance is adjusted to the perfect length.
Then some offsets are added on the macroscopic position of ETMs to see what will happen in the LSC sensing matrix.
When putting the offsets, the amount of offsets are randomly assigned with a Gaussian distribution (see Figure.1).
Therefore the calculation is a Monte-Calro style, but this doesn't have to be a Monte-Calro
because the parameter space is only 2-dimensions (i.e. X-arm and Y-arm length) and it can be done by simply scanning the 2-dimentional parameter space.
The reason why the Monte-Calro style was chosen is because I wanted to expand this simulation
to a more general simulation which can handle PRCL, SRCL and MICH misplacements as well.
This time I ran the Monte-Calro 1000 times.
 
random2cm.png
Figure.1 History of random walk in X-Y arm lengths parameter space.
The position of ETMY and ETMX are randomly chosen with a Gaussian distribution function in every simulation.
This example was generated when \sigma_x = \sigma_y = 2 cm, where \sigma is the standard deviation of 
the Gaussian function. The number of simulation is 1000 times.
 
 
 

(Criteria)
I made two criteria for the acceptable sensing matrix as follows :
  (1) The decrease in the optical gain of the important signals (diagonal signals) must be within a factor of 3 (factor of ~ 0.5 in log scale).
  (2) MICH and SRCL signals are separated within a range of 60 - 120 deg in their demodulation phases on POP55.
 

(Results1 : sensing matrix)
Figure.2 shows the resultant sensing matrix with histograms when \sigma_x = \sigma_y = 2,
where \sigma_x, \sigma_y are the given standard deviation in the position of ETMX and ETMY.
The diagonal signals (in red-rectangular window) shows variation in their optical gain within a factor of 0.5 in log scale (factor of 3 in linear scale).
This satisfies my requirement (1) mentioned in the last section.
 
 
 
armsensMAT.png
Figure.2  A sensing matrix of the 40-m DRFPMI while changing the position of ETMX/Y by \sigma = 2 cm.
For convenience,  only REFL11, AS55, POP11 and POP55 are shown. They are the designed signal ports that
mentioned in the aLIGO LSC document (T1000298). In all the histograms, x-axis represents the optical gain in log scale in units of [W/m].
The y-axis is the number of events. The diagonal ports are surrounded by red rectangular window.
 
 
 
 
(Results2 : demodulation phase of MICH and SRCL on POP55)
Now a special attention should be payed on the MICH and SRCL signals on POP55.
Since MICH and SRCL are designed to be taken from POP55, they must be nicely separated in their demodulation phases.
Therefore the demodulation phase of MICH and SRCL has to be carefully examined.
The plot in Figure.3 is the resultant phase difference between MICH and SRCL on POP55 when \sigma_x = \sigma_y = 2 cm.
As shown in the plot the phase are always within a range of 60 - 120 deg, which satisfies my requirement (2) mentioned in the last section.
 
 
 
 
POP55phase2cm.png
 Figure.3 Difference in the demodulation phase of MICH and SRCL on POP55.
x-axis is the difference in the demodulation phase of MICH and SRCL, and y-axis the number of events.
 
 

(Notes on the Optickle model)
Optickle that I used is the one downloaded from the MIT CVS server and I believe this is the latest version.
In my current simulation I omitted some foldng mirrors including PR3, SR2 and SR3.
If those mirrors are added on the model, loss from those mirrors will affect the build up powers in all the cavities and hence changes the sensinag matrix somewhat.
I assumed that each optic has loss of 50 ppm in its HR surface.
Input power, after the MC, of 1 W is assumed.
The modulation depth are all 0.1 rad for 11MHz and 55MHz.
The model files were uploaded on the MIT CVS server and files reside under /export/cvs/iscmodeling/40m/fullIFO_Optickle.
More information about the CVS server can be found on aLIGO wiki.
 
  5077   Sun Jul 31 22:35:35 2011 kiwamuUpdateLSCarm loss measurement : done

I did the measurement of the arm loss on both X and Y arm by running the armLoss script.

The results will be posted later.

Quote from #5074

I will measure the loss on the X and Y arm cavity tomorrow.

 

  5078   Sun Jul 31 22:48:35 2011 kiwamuSummaryGeneralpreparation of the vent : status update

Status update for the vent preparation:

The punchline is : We can not open the chamber on Monday !

 

##### Task List for the vent preparation #####

  (not yet) Low power MC

  (not yet) Measurement of the arm lengths

  (not yet) Alignment of the Y green beam (#5066)

  (not yet) Measurement of the MC spot positions

  (80% done) Estimation of the tolerance of the arm length (#5076)

  (done) Preparation of beam dumps (#5047)

  (done) Health check of shadow sensors and the OSEM damping gain adjustment (#5061)

  (done) Alignment of the incident beam axis (#5073)

  (done) Loss measurement of the arm cavities (#5077)

Quote from #5048

Quote:

The vent will start from 1 st of August ! 

 

  5079   Mon Aug 1 04:08:24 2011 kiwamuUpdateABSLArm length measurement : cavity kick technique

I made some attempts to measure the current length of the arm cavities by using the mass-kicking technique.

However unfortunately I am running out my energy to complete the measurement,

so I will finish the measurement at some time today.

I still have to set an appropriate kick amplitude. Right now I am injecting AWG into ETMY_LSC_EXC at 0.2 Hz with amplutde of 400 cnts.

I guess it needs a little bit more amplitude to get more psuedo-constant velocity.

Volunteers are always welcome !

 

(some notes)

The procedure was well-described in entry #555 by Dr.Stochino.

Here is just an example of the time series that I took today showing how the time series looks like.

ETMY_kick.png

  5080   Mon Aug 1 08:52:37 2011 steveUpdateVACpreparation to vent

Both arms locked easely around 1V transmited.  We should recenter oplevs.

  5081   Mon Aug 1 11:46:56 2011 ranaSummaryLSCTolerance of Arm length = 2 cm

wow. This Monte-Carlo matrix is one of the most advanced optical modeling things I have ever seen. We never had this for any of the interferometers before.

  5082   Mon Aug 1 16:06:05 2011 steveUpdateSUSoplevs are centered

Kiwamu, Koji and Steve,

Arm aligned separatly and oplev qpds were centered  including BS. Than we realigned manually DRM and centered their qpds.

ALL SUS oplevs were centered to resonating cavities.

  5083   Mon Aug 1 17:47:37 2011 steveUpdateASCwhat is not working

SUS-ETMY_QPD is not responding. It is reading zero in dataviewer and 4,400 counts on QPD MEDM screen.......must be wrong cable connected

IP-POS is sick. Last time alive 7-19-2011

IP-ANG beam is clipping on pick-up mirror at ETMY chamber. This will have to be fixed at the vent. The qpd itself is responding to light.

  5084   Mon Aug 1 20:21:05 2011 kiwamuUpdateGreen LockingY arm green beam axis : aligned

The beam axis of the Y green light has been aligned.

Now I can see TEM00 mode is flashing on the ETMY camera.

 

-- (What I will do tonight)

The next step is to refine some electronics in the PDH loops to get the green light locked to the Y arm cavity.

If the beam isn't locked, I guess the in-vac-work will be so difficult because of the low intensity of the green light.

According to a brief check on the circuits, a low pass filter after the demodulation mixer is in a sad situation.

It doesn't pass any signals and in fact it behaves more like an absorber.

On the other hand, the modulation system looks fine to me because I was able to see the 270 kHz sideband converted into AM due to the fringing.

Quote from #5078

  (not yet) Alignment of the Y green beam (#5066)

  5085   Mon Aug 1 22:30:59 2011 kiwamuSummaryGeneralWeekly report

Summary of the week ending July 31st.  Number of elog entries = 53


- SUS
 + ETMY-LR sensor looked strange. Something wrong.
 + Responses from the DC alignment bias to the shadow sensors and the oplevs were checked.
   --> ETMY shows the response with the opposite sign. Wired.
 + ETMY shadow sensors were examined in terms of the spectra.
   --> WF, AA and ADC noise looks reasonably low and not high enough to explain the low frequency noise.
 + Adjusted all the OSEM gains

- LSC
 + MICH noise budget is ongoing. WF filter needs to be greater than 21 dB to have dark noise of the PD greater than ADC noise
 + The arms became lockable

- CDS
 + modified and re-ran activateDQ.py.
 + c1iscex crashed for unknown reasons and we physically rebooted it.

- ALS (Fiber experiments)
 + PMC trans is sampled for the fiber beat-note measurement on the PSL table.
 + The beat-note signal between PSL and X end laser were obtained.
 + Some optics in the ETMY table were rearragend to have the Y green light aligned.

- ACS / ASS
 + incident beam axis has changed a lot.
 + X arm and Y arm ASS were reactivated.
  ---> The sign of some of the control gains had been wrong.
 + The incident beam axis and X/Y arm were re-aligned

- IOO/MCWFS
 + Some medm screens fixed.
 + Adjustment of the demodulation phase on each quadrant on WFS1 and WFS2 are done.
 + The sensing matrix (from optics to WFS sensors) were measured.

- OAF
 + c1pem was modified
 + plugged a seismometers to ADC through an AA board.
   --> channels are coming to the digital land
 
- Preparation for the invac work
 + 7 pieces of beam traps are available
 + Tolerance of the arm length is estimated to be +/- 2 cm.


- PSL/RefCav
 + ABSL is injected into the reference cavity. some flashing happened but no locking.
 + eddited the psl.db file to set EGUF and EGUL
 + turned RefCav heater and servo back on

  5086   Mon Aug 1 23:26:32 2011 KojiUpdateLSCREFL33 PD

Old MZ PD (InGaAs 2mm, @29.5MHz) has been modified for REFL33.
There has been no choice for the 11MHz notch other than putting it on the RF preamp
as the notch in parellel to the diode eats the RF transimpedance at 33MHz.

I wait for judgement of Rana if the notch at the MAX4107 feedback is acceptable or not.

P8011390.JPG

ELOG V3.1.3-