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ID Date Author Type Categorydown Subject
  8556   Thu May 9 01:36:32 2013 ManasaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress

Progress with end table:

Parts in green show assembled optics that will not require any changes. Parts in yellow are in place but will need either change of lenses in their optical path or change in position.


  8560   Thu May 9 22:29:23 2013 ManasaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress

[Annalisa, Manasa]

More optics have been put on the table. Direction of the rejected beam from the 532nm faraday estimated to be ~1.7 deg along -y axis.

Transmon QPD, TRY and camera have beams on them for locking Y arm. Oplev configuration is waiting for it's lens to arrive.


  8561   Fri May 10 20:05:21 2013 AnnalisaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress

I rotated some mounts along the green beam path, and I started aligning the beam again.

The beam is aligned up to the waveplate just before the doubler crystal, even if I couldn't reach more than 88% transmission for the Faraday. Next week I will finish the alignment and I'll put the lenses that Manasa already ordered.


  8565   Mon May 13 21:35:55 2013 AnnalisaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress

Yend table - Current status


Today the 2m focal length lens along the oplev path (just after the laser) has been added. In Manasa's layout it allows to have a beam waist of 3.8mm on the OPLEV QPD, even if it seems to be smaller.

The laser is closer to the box wall than the layout shows (it's on the line n.1 instead of line n.9), so maybe it has to be moved in the position shown in the layout, as Steve suggests, to leave empty space just before the window.

Rana suggests a 2mm diameter beam on the QPD, so a new calculation has to be done to add a second lens.


The beam has been aligned until the doubler, but after the crystal it it has a small tilt, so a better alignment has to be done.

Moreover, the beam waist has to be measured after the Faraday for the green, in way to choose the focal length of the lenses necessary for the mode matching.

Then the three steering mirrors to send the beam into the arm have to be put.


A lens which has to be put on the Transmon path (already ordered) has to be added, and the beam alignment on the QPD-y and on the PDA520 has to be done.

  8568   Tue May 14 01:13:35 2013 JenneUpdate40m UpgradingTRY realigned

Koji noticed that earlier this afternoon the Yarm ASS was working, but then after dinner it was no longer working.  I saw that the ETMY trans camera beam was clipped.  These things precipitated a visit to the Yend station. 

I saw that the beam on the optic that steers the camera beam to the camera was very, very low, almost falling off the optic.  The only mirror which steers to this optic is the harmonic separator which reflects the IR, and transmits the green.  I turned the pitch knobs on the harmonic separator until the beam was roughly centered on all 3 optics between the separator and the camera (BS to QPD, BS to TRYDC and Y1 for camera).  The yaw was fine, so I didn't touch it.

I then adjusted the steering mirror to the camera, and the BS pointing to the DC PD.  I have not touched the BS pointing to the QPD.  Once the beam was on the TRY PD, Koji ran the ASS script, and I recentered the beam on the DC PD.  During this time, Koji had the Yarm triggering using -1 in the POYDC element of the matrix.

The harmonic separator is not mounted in a nice way (I'm assuming that Annalisa is in the middle of things, and she'll get back to it after the green work), so the TRY PD and camera will need to be aligned again, so I didn't do any ASS-recentering-ASS iteration tonight.

The Yarm ASS works nicely again, getting TRY to ~0.89 . 

  8571   Tue May 14 14:24:56 2013 SteveUpdate40m Upgradingenclosure removal


 I'm planning to remove the ETMY optical table enclosure and move it over to CES Shop 8am Thursday morning.

We'll install spring loaded lathes, hooks and quick release pins.

The bridge will be reinforced with steel plate to support release pins on posts.

There will be an other cut out for cable feedtrough as it is shown on elog #8472

Let me know if this timing does not fit your work.

  8576   Tue May 14 21:03:15 2013 AnnalisaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress



The new lenses arrived, and I put the right 250mm before the doubler. I'm still not so confident with the alignment, because I cannot get more than 11-12 uW out from the "green" Faraday, with more than 200uW going in.


I replaced the Y1 mirror with an HR1064-HT532. The alignment has to be done. Today the 50cm focal length lens arrived, and I'm going to put in tomorrow.


  8584   Wed May 15 21:27:39 2013 AnnalisaUpdate40m UpgradingEndtable upgrade for auxiliary green laser : progress



I still have problems in maximizing the power out from the doubler. I realized that the real green power I obtain is about 30 uW, and it is the power which really enters the Faraday.

Before I was measuring it just after the Harmonic separator, and there was some residual IR beam which increased the power on the power meter, that's why I obtained about 200 uW.

I also tried to slightly vary the position of the mode matching lens, but I was not able to get more than 30 uW on the power meter.


The 50 cm focal length lens has been added in the position shown on Manasa's layout, and the beam has been focused on the PD.



  31   Tue Oct 30 16:55:40 2007 tobinRoutine Drag-wiping perfected
Steve, Tobin

Steve procured an assortment of syringes from the bio storeroom and we practiced drag-wiping the SOS in the flow bench. Using a 50 microliter Hamilton syringe to deliver 16 microliters of methanol seems perfect for drag-wiping the small optics. Drag-wiping in the downward direction seems to work very well, since we can squirt the optic directly in the center, and the (half) piece of kodak lens tissue fits easily between the bottom two earthquake stops.
  108   Thu Nov 15 18:36:48 2007 JohnSummary PSL table work
I've rotated the lambda/2 plate to 340deg (from 6 deg) and blocked one arm of the Mach-Zender. Undo both if you need to.
  130   Wed Nov 28 12:43:53 2007 AndreyBureaucracy Here was the PDF-file of my presentation

I was making a report with powerpoint presentation during that Wednesday's 40-m meeting.

Here was the pdf-file, but LATER IN THE EVENING I CREATED A WIKI-40M-page describing the algorithm, and now the pdf-file is ON THAT WIKI-40M PAGE.

NOTE ADDED AFTER THE PRESENTATION: I double checked, I am indeed taking the root-mean-square of a difference, as we discussed during my talk.

My slide #17 "Calculation of differential length" was wrong, but now I corrected it.
  215   Thu Dec 27 12:12:02 2007 pkpUpdate Update on GigE Camera
So I finally got the linux software to compile on mafalda. I got the software to dump all the information regarding the camera onto a file. I tried to take a tiff snap and came up empty. So I looked at the configuration file and realized that the camera thinks that the frame-rate is a nan. Am reading up the manual to fix the frame-rate manually and then will attempt to take another snap.

All the files are in a folder called Prosilica in /home/controls/ on mafalda. All the executables are in /home/controls/Prosilica/bin-pc/x86/* . On another note, I am looking for a name for the camera. Any suggestions are welcome.
  254   Wed Jan 23 09:27:55 2008 steveUpdate etmy sus damping restored
Seismis event trips etmy
  548   Fri Jun 20 02:20:33 2008 YoichiUpdate PMC transmittance degradation
The PMC transmitted light power has been degrading constantly for last two weeks (see the attachment 1).
I went down to 2.55V.
The output of the MOPA is constant during this period. More strangely, the reflected power from the PMC is also constant.
One possible explanation is the contamination of the PMC mirrors. But I don't know why it started two weeks ago.

I tweaked the alignment of PMC and was able to recover the transmitted power to above 2.7V (attachment 2).
I will keep eye on this issue.
  563   Wed Jun 25 09:46:45 2008 SharonUpdate Adaptive Filters
I have been learning about different methods for applying adaptive filters to improve the Mode Cleaner lock in specific, and other LIGO systems in general.
Finding the exact number of coeffs we would like to apply for our FIR adaptive filter is very important to the efficiency of the filter. Getting this number higher might improve the accuracy of the filter, but costs time we do not have. Another important number to find is the step size. The step size is the variable that controls how far back we want to look into our data for finding the new coeffs. To understand more about the step size it is necessary to learn about the standard deviation of our input and output signals. By getting the step size too big, we are considering long term behavior, but might be missing out on a short term one.
In the near future I will be learning about the meanings of these variables and their contribution to the over all accuracy of our filters.
Results will be posted.
  577   Thu Jun 26 18:29:44 2008 JenneUpdate MC Back online
Jenne, Rob, Yoichi

I was playing with the Mode Cleaner earlier today, working on measuring the effect of the new filter (see next post for loop gain measurements etc.), and bumped something which made it so the Mode Cleaner would not lock.

After much poking around by Rob and Yoichi, we found that the TNC-to-2 pin LEMO from Out1 of the MC Servo Board to Ch1 of the Pentek Generic board to the right of the MC Servo Board was bad. If we touched the cable, the MC would lock, but as soon as we let go, the MC would fall out of lock. The LEMO end of the cable was not heat shrink wrapped, so the 2 wires could have been touching. I replaced the cable, and the MC locked immediately after plugging it in, so I think that has fixed the problem.
  680   Wed Jul 16 11:26:47 2008 Max JonesUpdate This Week

I got a battery for the magnetometer today which is slightly too large (~2 mm) in one dimension. Not sure what I'm going to do.

I'm attempting to calibrate the magnetometer but I'm having a hard time calibrating the axis that I cannot simply put through a coil parallel to the coils length. I have attempted to use the end fields of the solenoid but the measurements from the magnetometer are significantly different from the theoretical calculations.

I would appreciate suggestions. - Max.
  704   Mon Jul 21 09:52:05 2008 SharonUpdate Adaptive code changes
Thanks to Alex, we now save the coefficients of the adaptive filter every cycle. When we choose ENABLE: OFF on the MEDM screen, suppressing the signal to the MC1, we stop and save the last coefficients. When enabling it again, it starts from the last coefficients saved. I will take some measurements today to check how this contributes to the adaptation rate. If you change the number of taps or the number of AUX channels, the coefficients are again set to zero.
  709   Mon Jul 21 19:48:57 2008 SharonUpdate how tp restart C1ASS
How to restart C1ASS:

1. reboot
2. as root: caltech/target/c1ass:> ./startass
3. no need for root: burtgooey

that's it...
  720   Wed Jul 23 10:47:05 2008 SharonUpdate Weekly update
This week I spent some time with Alex who updated the adaptive code to save the filter's coeffs all the time, stop when I open the loop, and reload the latest coeffs. when I start it again.
The point was to minimize the adaptation rate. Unfortunately, seems it is making some filters go wild, so it is not in use yet.
After taking some more measurements with the adaptive filter running, I have noticed a new peak in the signal around 22-23 Hz. My first assumption was that this is caused due to internal resonance of MC1 (which is driven when the adaptive code is running, and not when it's not). Therefore, I drove MC1 without the adaptive filter looking for the same peak... which wasn't there.
This sent me back to the adaptive code... Seems there is a matrix in the simulink file of the adaptive filter which doesn't have an MEDM screen. I am now working on making this screen. Once I am done with that, and make sure there is correlation between simulink and MEDM, I'll keep on chasing the peak in the code.
  723   Wed Jul 23 13:52:26 2008 SharonUpdate MEDM changes
There is a new MEDM screen now when you go from c1ass>top>pem.
Instead of having 12 "mini filters" screens go to 8 outputs (with the wrong correlation impression from the table), we have a 24X8 matrix.
This matrix is there so you could choose which noise signals you want to send to the adaptive code. When you indicate the number of noise channels you are going to use
on the nAUX option on the screen top, you are choosing the channels 1 to nAUX. Channels 15-22 are the seismic and accelerometers we are now using. (you can see the order in Jenne's post 673).
Hope this will make things clearer.
  739   Fri Jul 25 13:30:53 2008 SharonUpdate Changes in ASS computer
I editted the simulink diagram of the ASS computer so it now has 2 more channels reading 2 sets of the FIR coefficients to match Alex's changes in the C code.
The new simulink has already been compiled and can be found in /cvs/cds/caltech/users/alex/cds/advLigo/src/epics/simLink/ass.mdl
I backed up the old file and it's also in that folder under ass_BAK_24_jul.mdl

There is also a backup of the old ASS.ini file in caltech/chans/daq/C1ASS_BAK_24_jul.ini

Will update once it's all set and running
  740   Fri Jul 25 17:32:46 2008 SharonUpdate ASS computer
So, it seems a bit too complicated getting the coefficients the way I wanted it to happen (simulink-.ini...).
I returned everything to the way it was and it's all working. The new plan is to choose the specific channel I want to find its instantanous coefficients, let the adaptive code run for a while, setting mu and tau to zero (freezing the coefficients), and exciting the noise signal channel taking the transfer function. This way I can find the filter I want to simulate with an IIR filter.
Once I have the mode cleaner to myself, I'll start posting results.
  747   Mon Jul 28 12:02:32 2008 SharonUpdate accelerometers settings
Jenne, Sharon

We looked again at the channels of the accelerometers and there are some updates. Last time when we reported, we crossed the ADAP channels and the accelerometer. Now that there is a new MEDM screen, with which you can control which channels goes to which adaptive channels, this has no meaning...
Therefore, the channels that go with the noise source channels are:

PEM 15 MC1_X
PEM 16 MC1_Y
PEM 17 MC1_Z
PEM 18 MC2_X
PEM 19 MC2_Y
PEM 20 MC2_Z

disregard the last post regarding these channels by Jenne, since I am changing the ADAP channels all the time...
  750   Mon Jul 28 17:58:05 2008 SharonUpdate TOP screen changes
I wanted to test the adaptive code with a downsampling rate of 32 instead of 16. To do this I entered a 32 Hz ((2048/32)/2 - match Nyquist Freq.) low pass filter on the ERROR EMPH, MC1 and the relevant PEM channels.
  760   Tue Jul 29 21:04:55 2008 SharonUpdate OSEM's Power Spectrum
From 16:30 this afternoon
  765   Wed Jul 30 12:36:19 2008 SharonUpdate Weekly update
This week included many computer's issues. I tested Alex's new C code (the one that saves the FIR coefficients and restores them when you start running the code again). Seems there is an improvement in the adaptation time, but not a significant one (more details on the coming report). I had to recompile simulink and the FB whenever I wanted to find a solution for taking the record of those coefficients. This is so I could simulate the adaptive filter with a regular IIR filter and compare the two.
After Rob tried to help and it seems to be an impossible to a huge hassle mission, we thought of a different method to do this. I re-compiled the old simulink file and restored the .ini file and all should be back in place. Instead of finding the FIR coefficients, I am going to use one noise source in the adaptive filter, stop the adaptation (by setting mu and tau to 0), and put excitation instead of the noise signal. The transfer function I will get between the exc. and MC1_IN1 is the filter I am looking for.

Also seems that whenever I get the MC unstable, and the adaptive code stops itself, it doesn't come back. Setting the reset flag to a different number (anything other than 0) and pressing the reset button will get it working again, but the CPU will always flip and the ASS computer needed a restart. Still haven't found a problem in the C code, but that's the plan. Moreover, I want to change Alex's code, so that instead of starting from zero like in Matt's code, or starting from the old coefficients like in Alex's, it is going to calculate a Wiener Filter as the first set of coefficients. This will hopefully reduce the adaptation time.

I have also been working on my progress report, and stood in line for the MC... Still standing...
  814   Fri Aug 8 11:04:34 2008 SharonUpdate MCL Wiener filter
I took some old data from Rana and converted the units of the Weiner filter to m/m so to make the effect of the seismometer and accelerometers more obvious.

The data is in counts, and so to convert to m this is what I did:

%%% MC_L calibration
v_per_counts = 5/32768;
v_per_v = 3;
amp_per_N = 1/0.064;

%%% Accelerometers calibration
v_per_counts_acc = 61.045e-6;
g_per_v = 9.8/100;

%%% Seismometer calibration
v_per_counts_seis = 61.045e-6;
m_per_s_per_s_per_volt = 9.8/100;
m_per_v_per_s = 1/345;

for jj=1:6
hfmatm(:,jj)=hfmat(:,jj).*(v_per_counts.*v_per_v.*amp_per_N.*f)./(v_per_counts_acc*g_per_v); %%% accelerometers' data
hfmatm(:,7)=hfmat(:,7).*(v_per_counts.*v_per_v.*amp_per_N)./(v_per_counts_seis*m_per_v_per_s); %%% Seismometer data
  841   Fri Aug 15 16:45:43 2008 SharonUpdate Converting from FIR to IIR
I have been looking into different techniques to convert from FIR to IIR. This is so we can see how effective the adaptive FIR filter is in comparison to an IIR one with fewer taps.
For now I tried 2 matlab functions: Prony and stmcb (which works on LMS method).
I used the FIR wiener code, MC1_X, (c1wino) and applied the FIR to IIR algorithm.
Seems like the stmcb one works a bit better, and that there isn't much effect for having 1000 and not 400 taps.

Will keep updating on more results I have, and hopefully have the MC in time to actually check this live.
  850   Tue Aug 19 10:36:34 2008 SharonUpdate Calibrating accelerometers
I took apart the accelerometers near MC1 and MC2.
The 2 sets of 3 accelerometers are now covered by a box on the floor. Please try not to move them... I will place it all back once I am done calibrating.
  854   Tue Aug 19 17:00:19 2008 SharonUpdate Wiener TF calibration - update
This is an update for post 814

I added the calibration gains I got for the accelerometers (I realize I am just calibrating the accelerometers to themselves and this is not m/m exactly since we don't really know which accelerometer is doing exactly what we want it to do. However, since we are talking on relative small numbers, this shouldn't really change much).

I also added another missing gain for the seismometer. Rana has previously installed a 4300 ohm resistor in the seismometer, which changed the gain to 4300/(4300+5000) = 0.46 (this is from the manual). Moreover, there is a gain of 100 on the SR560. This comes up to an extra gain of 46, meaning multiplying the seismometer's counts by 1/46.
  855   Tue Aug 19 17:15:34 2008 SharonUpdate MEDM
I plugged in the gains I got for the accelerometers in the accelerometers' filters in the PEM screen of the adaptive filter
  863   Wed Aug 20 17:02:01 2008 SharonUpdate More FIR to IIR
I tested another method for converting from FIR to IIR other than the 2 mentioned in post 841.
I got this one from Yoichi, called poles fitting, you can read about it more if you want at: http://www.rssd.esa.int/SP/LISAPATHFINDER/docs/Data_Analysis/DA_Six/Heinzel.pdf.

Seems it's not doing much good for us though.

I am attaching a PDF file with the plots, which have N=50,100,600,1000, respectivaly.
  870   Fri Aug 22 13:58:39 2008 SharonSummary Trend of the Wiener TF
In order to understand if we really need an adaptive filter, I used old data of MC_L and the accelerometers and seismometer to see if the Wiener (ideal) TF between MC_L and the others really changes all the time.
Two tests I made:
  • Compare the TF after different segments of time, starting from the same point. Meaning, measuring the TF after 5,10,15,20... minutes, looking when and if the TF stablizes (stops changing).
  • Compare the TF between same-length segments, from different times. Meaning, comparing for example 2 segments of 10 minutes taken from different times.

  • As you can see in the attached PDF, the changes start being minor after 200,000 data points, which correspont to 200,000/256 s, which is approximately 13 minutes.
    If you look at the PDF file, it is arranged from shorter times to longer in the order of: 3, 6, 13, 26 and 39 minutes.

  • As expected, the TF between different segmants of the same length is not completely the same. Again, you can look at the attached PDF.
    Sorry the titles are the same. Each 2 consecutive pages represent the same length of segment in different times. The order of segment's lengths is: 3, 13, 26 and 39 minutes

How do I explain what's going on?

Since the Wiener filter finds the correlation matrix between the data and the noise signals, it will maintain some kind of familiar shape when we don't add a significant amount of unusual data. I am assuming that if I had looked at longer time periods, we could see a more significant change in the TF in time. When looking at different times, the average noise is likely to be different which can explain the change in the correlation matrix and the TF.

To sum up

I think we should give adaptive filtering a go.
  916   Wed Sep 3 18:45:01 2008 AlbertoConfiguration PD3 gain
Alberto, Yoichi,

We found that the PD3 servo was unstable with a gain of 1, so we switched it to 0.5
  1442   Mon Mar 30 12:29:17 2009 YoichiConfiguration MC1 glitches not seen during the weekend
The attached is the MC trend for the past 12 hours.
There is no MC1 glitches in the OSEM signals. Moreover, the total amplitude of the drift is smaller than it used to be (now the amplitude is less than 100 but it used to be a few hundreds).
There still is a small step in the OSEM signals at around 6AM this morning, but the amount of the jump is very insignificant.
The cause of the glitch in the TMP1, DRUM1 and APTEMP (LL, UL and UR coils respectively) at 7AM is not known.
Since the MC1 has been behaving OK during the weekend, I removed the probes from the MC1 coil driver board and locked the MC.
Hopefully the replacement of the broken connector fixed the problem, but I'm not sure.
  1556   Thu May 7 17:59:23 2009 AlbertoConfiguration MC WFS
This afternoon the MC could not get locked.
I first checked the Osems values at the MC mirrors and compared them to the trend of the last few hours. That showed that the alignment of the mirrors had slightly changed. I then brought each mirror back to its old alignment state.
That let the LSC loop lock the MC, although the reflected power was still high (1.5V) and the WFS control wouldn't engage.
Since earlier during the day I was working on the AS table, it is possible that I inadvertently hit the MC REFL beam splitter misaligning the beam to the MC WFS.
To exclude that there was a problem in the suspensions, before touching the WFS, I checked that the cables at the MC's ends and those going to the ADC in the rack were well pushed in.
Then I proceeded in centering the beam on both the WFS, balancing the power over the QPDs.
In the end the MC could lock again properly.
  1739   Mon Jul 13 16:59:10 2009 ZachUpdate GigE Phase Camera

Today, I moved the router from on top of the PSL into the control room in order to perform dark field tests on the GC650 (which I also moved).  The GC750 along with the lens that was on it and the mount it was on has been lent to Ricardo's lab for the time being.  I successfully triggered the GC650 externally and I also characterized the average electronic noise.  For exposure times less than 1 microsecond, the average noise contribution appears to be a constant 15 on a 12-bit scale.

  1797   Mon Jul 27 14:43:34 2009 ChrisUpdate Photodetectors

I found two ThorLabs PDA55 Si photodetectors that says detect visible light from DC to 10MHz that I'm going to use from now on.  I don't know how low of a frequency they will actually be good to.

  1907   Fri Aug 14 18:33:02 2009 ClaraUpdate Record of Accelerometer and Seismometer Movements

Rather than make a new elog post every time I move something, I'm going to just keep updating this Google spreadsheet, which ought to republish every time I change it. It's already got everything I've done for the past week-ish. The spreadsheet can be accessed here, as a website, or here, as a pdf. I will still post something nightly so that you don't have to search for this post, but I wanted to be able to provide more-or-less real-time information on where things are without carpet-bombing the elog.

  2984   Tue May 25 17:04:37 2010 KevinUpdate Beam Profile After Mode Cleaner

I fit the data from the beam profile that Jenne measured on 5/21/2010. The distances are measured from halfway between MC1 and MC3 to the beam scanner. The fits give the following where w0 is the waist size and z0 is the distance from the waist to halfway between MC1 and MC3.

For the horizontal profile:

reduced chi^2 = 0.88

z0 = (1 ± 29) mm

w0 = (1.51 ± 0.01) mm

For the vertical profile:

reduced chi^2 = 0.94

z0 = (673 ± 28) mm

w0 = (1.59 ± 0.01) mm

I calculated the radius of curvature of MC2 using these values of w0:

horizontal: (16.89 ± 0.06) m

vertical:   (17.66 ± 0.07) m

For this calculation, I used the value of (13.546 ± .0005) m for the length of the mode cleaner measured on 6/10/2009. The specification for the radius of curvature of MC2 is (18.4 ± 0.1) m.

In the following plots, the blue curve is the fit to the vertical beam radius, the purple curve is the fit to the horizontal beam radius, * denotes a data point from the vertical data, and + denotes a data point from the horizontal data.

  3027   Tue Jun 1 18:39:59 2010 NancyUpdate Lead spheres for the seismographs


the lead spheres that were placed below the granite slab have been flattened by hammering to have lesser degree of wobbling of the slab.

the height of each piece, and the flatness of their surfaces was checked by placing another slab over them and checking by the spirit level.





  3168   Wed Jul 7 12:45:00 2010 nancyUpdate Weekly Update

Wednesday after the meeting - Started report, learnt mode cleaner locking from Kiwamu and Rana, saw how to move optics on the tables with Rana and kiwamu.

Thursday - Made the report

Tuesday - report.

Today - am trying locking the MC with kiwamu's help to see the WFS signals and also to start characterizing the QPD.

  3560   Sun Sep 12 23:02:53 2010 valeraUpdate PMC mode matching

Kiwamu and I found that the first lens in the PMC mode matching telescope was mislabeled. It is supposed to be PLCX-25.4-77.3-C and was labeled as such but in fact it was PLCX-25.4-103.0-C. This is why the PMC mode matching was bad. We swapped the lens for the correct one and got the PMC visibility of 82%. The attached plot shows the beam scans before and after the PMC. The data were taken with the wrong lens. The ABCD model shown in the plot uses the lens that was there at the time - PLCX-25.4-103.0-C. The model for the PMC is just the waist of 0.371 mm at the nominal location. The snap shot of the ABCD file is attached. The calculation includes the KTP for FI and LiNb for EOM with 4 cm length. The distances are as measured on the table.

  3561   Sun Sep 12 23:16:52 2010 valeraUpdate FSS mode matching

The attached plot shows the beam scans of the beam leaking from the back mirror of the PMC to the BS cube that first turns the S-pol beam 90 deg to the AOM and then transmits the AOM double passed and polarization rotated P-pol beam to the reference cavity. The beam from the PMC is mode matched to the AOM using a single lens f=229 mm. The ABCD file is attached. The data were taken with VCO control voltage at 5 V. We then reduced the voltage to 4 V to reduce the astigmatism. Tara has the data for the beam scan in this configuration in his notebook.

The beam from AOM is mode matched to the reference cavity using a single lens f=286.5 mm. The ABCD file is attached.

  3562   Mon Sep 13 00:19:32 2010 ranaUpdate VCO Driver Output power v. slider control voltage

I measured the RF power output of the VCO Driver box as a function of slider value. I measured using the Gigatronics Handheld power meter and connected to the AOM side of the cable after the white Pasternak DC block.

* at low power levels, I believe the waveform is too crappy to get an accurate reading - that's probably why it looks non-monotonic.

* the meter has a sticker label on it saying 'max +20 dBm'. I went above +20 dBm, but I wonder if maybe the thing isn't linear up there...

  3579   Wed Sep 15 19:29:13 2010 valeraSummary PSL power budget
 Location  Power (mW)
 NPRO - after HWP  252
 Rejected by input FI polarizer  38
 After output FI polarizer  175
 Into PMC  164
 PMC reflected  37
 PMC transmitted  71
 PMC leakage  1.5
 After PMC TRANS PD/Camera BS


 After RefCav EOM  1.1
 Into RefCav  0.3


- NPRO injection current 1.0 A

- PMC losses ~32%

- FSS AOM diffraction efficiency ~52%

  3580   Fri Sep 17 01:36:14 2010 valeraUpdate PMC line width

The attached plots show the PMC cavity line width measurement with 1 mW and 160 mW into the PMC. The two curves on each plot are the PMC transmitted power and the ramp of the fast input of the NPRO. The two measurements are consistent within errors - a few %. The PMC line width  3.5 ms (FWHM) x 4 V / 20 ms (slope of the ramp) x 1.1 MHz / V (NPRO fast actuator calibration from Innolight spec sheet) = 0.77 MHz.

Here is the output of the calculation using Malik Rakhmanov code:


modematching =  8.4121e-01

transmission1 =   2.4341e-03

transmission2 =   2.4341e-03

transmission3 =   5.1280e-05

averageLosses =  6.1963e-04

visibility =  7.7439e-01

Here are the inputs for the calculation in the param.m:


fw = 0.77e6;                % width of resonance (FWHM) in Hz

Plas = 0.164;                % power into the PMC in W


% the following number refer to the in-lock cavity state


Pref = 0.037;                % reflected power in W

Ptr = 0.0712;                 % transmitted power in W

Pleak = 0.0015;              % power leaking from back of PMC in W



  3897   Thu Nov 11 15:27:43 2010 valera, steveConfiguration ISS AOM installed

 We installed the ISS AOM in the PSL. The AOM was placed right after the EOM. The beam diameter is ~600 um at the AOM. The AOM aperture is 3 mm.

We monitored the beam size by scanning the leakage beam through the turning mirror after the AOM. The beam diameter changed from 525 um to 515 um at a fixed point. We decided that the AOM thermal lensing is not large enough to require a  new scan of the mode going into the PMC and we can proceed with PMC mode matching using the scan that was taken without the AOM (to be posted).

  4317   Thu Feb 17 22:51:04 2011 josephb, valeraSummary dither alignment model

We made a model for the dither angular stabilization system c1ass.mdl. The attached file shows the diagram.

The idea is to dither a combination of 6 optics (ETMs, ITMs, PZTs) at different frequencies and demodulate three PDs (TRX, TRY, REFL11I). Then form the DOFs from demodulted signals, filter, and send each DOF to a combination of optics.

This is enough to get started with arm cavities alignment (we may need to add the BS for the Y arm). More optics and PD can be added as they become available and/or needed.

The DAC for the fast PZT  are not connected and have to be commissioned.

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