40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 51 of 344  Not logged in ELOG logo
ID Date Authordown Type Category Subject
  7414   Wed Sep 19 23:17:25 2012 ranaConfigurationPSLAOM installation

Mannasa and Unni and I looked at the RF driver for the AOM. It was fine.

With the ALC input left unconnected, with the power supply set to +28V, it was drawing 0.56 A.

By adjusting the modulation input we were able to get 1.1 Vrms into the scope (terminated at 50 Ohms) after going through 2 10dB attenuators. 11 Vrms into 50 Ohms is 33.8 dBm ~ 2W.

The RF power trimpot on the front of the driver is now adjusted so that -0.31 to 0.69 V takes the driver output from off to 2W output at 80 MHz.

 

The previous distorted signal that Jan and Manasa saw was at a level of ~100 mVrms, which is ~0.5 mW of power. At this tiny drive level, the internal amplifier is not linear and is mostly putting out a signal at ~160 MHz.

 

We checked by putting a square wave into the modulation input that the RF power from the driver would indeed shut off with a time scale of ~20 ns. Manasa will add a picture to this entry. We are ready now to calibrate the transmitted power of the AOM v. the modulation input voltage and then to measure the step time of the AOM.

Remember: do NOT believe the spec sheet of whatever PD you are using. All commercial PDs are slower than they advertise. In order to measure a <1 us step time you must use a PD with a >50 MHz 'bandwidth'.

  7435   Mon Sep 24 20:28:13 2012 ranaSummaryelogrestarted elog: was unresponsive
  7436   Mon Sep 24 23:45:39 2012 ranaUpdateGeneralPOP in-vac optics aligned, POY beam coming out of vac

  What was the reasoning / resolution of the POP forward/backward beam? Are we going to have the right beam for DRMI locking?

  7459   Mon Oct 1 19:21:03 2012 ranaConfigurationPEMchanged PEM DQ channels

Changed the list of channels to be written to frames from having the IN1 suffix to OUT. Now we can load the calibration of the channel into the filter module and the DQ channel will be calibrated.

We should do this wherever possible so that our channels will have real calibrations associated with them.
SEIS_GUR1_X_OUT 256
SEIS_GUR1_Y_OUT 256
SEIS_GUR1_Z_OUT 256
SEIS_GUR2_X_OUT 256
SEIS_GUR2_Y_OUT 256
SEIS_GUR2_Z_OUT 256
SEIS_STS_1_X_OUT 256
SEIS_STS_1_Y_OUT 256
SEIS_STS_1_Z_OUT 256
SEIS_STS_2_X_OUT 256
SEIS_STS_2_Y_OUT 256
SEIS_STS_2_Z_OUT 256
SEIS_STS_3_X_OUT 256
SEIS_STS_3_Y_OUT 256
SEIS_STS_3_Z_OUT 256
MIC_1_OUT 2048
MIC_2_OUT 2048
MIC_3_OUT 2048
MIC_4_OUT 2048
MIC_5_OUT 2048
MIC_6_OUT 2048
ACC_MC1_X_OUT 2048
ACC_MC1_Y_OUT 2048
ACC_MC1_Z_OUT 2048
ACC_MC2_X_OUT 2048
ACC_MC2_Y_OUT 2048
ACC_MC2_Z_OUT 2048
XARM_DIFFERENTIAL_MOTION_IN1 256
XARM_DIFFERENTIAL_MOTION_OUT 256
YARM_DIFFERENTIAL_MOTION_IN1 256
YARM_DIFFERENTIAL_MOTION_OUT 256

Next we should up the rate at which the model runs up to 16 kHz so that we can record the microphones at 16 kHz. FM radio has information up to 20 kHz. AM radio goes up to ~8 kHz. We should be at least as modern as AM radio. How do we make the change? How do we make sure the FOTON file stays OK?

I have made some changes to the daily summary file to compensate. New files is /users/public_html/40m-summary/share/c1_summary_page.ini.

  7489   Fri Oct 5 04:34:31 2012 ranaUpdateSUSHow about the slow machines?

Quote:

Quote:


Based on the elog entries, I assume they have not been burtrestored...

 Do you know how to burtrestore or restart slow machines?

Edit by Den: I did burtrestore of c1psl.snap from 2 days ago. Still slow machines behave not normal. For example, if I sweep C1:PSL-FSS_SLOWDC, SLOW monitor value does not change.

 Problems with Slow Machines?

Read ELOG

  7499   Mon Oct 8 09:51:30 2012 ranaUpdateModern Controlstate estimation

 

 I guess that the estimated state has the same low pass filter, effectively, that we use to low pass the feedback signal in SUSPOS. I wonder if there is an advantage to the state estimation or not. Doesn't the algorithm also need to know about the expected seismic noise transmission from the ground to the optic?

  7507   Mon Oct 8 22:07:46 2012 ranaUpdateSUSDoors on, ready to pump

Quote:

All oplevs need a little realignment, especially ETMY, which had it's lens removed (Rana has a Wall of Shame photo of this, which is why it was removed by him).  Steve will look into this tomorrow, after he starts pumping.

 The shame:

20120921_200637.jpg

There is no situation in which it is OK to install a mount like this. Steve had installed this flaky and shaky mount to optimize the beam size on the OL QPD.

Everyone in the lab should know better. Putting in something like this is just like sabotage - it creates extra noise in our interferometer in a sneaky way and just makes locking harder. All mounts for anything useful (including QPDs) must have highly rigid mounts. 

Use the example from the PSL relayout: use the 3/4" steel mounts and the wide aluminum bases from Newport. No more art projects using home made mounting crap, Steve.

  7515   Wed Oct 10 02:15:14 2012 ranaUpdateLSC11 MHz reconnected to EOM

 Absolutely hokey. What are our requirements for this RFPD? What are the power levels and SNR that we want (I seem to remember that its for 22 as well as 110 MHz)? Perhaps we can test an aLIGO one if Rich has one sitting around, or if the aLIGO idea is to use a broadband PD I guess we can just keep using what we have.

  7516   Wed Oct 10 02:20:34 2012 ranaUpdateSUSOptical Lever QPD mods

 Since we upgraded the CDS system, I guess our ADC ranges have gone up but we never did anything to the OLs to match the ADC ranges. From Liz's daily summary page of the OL, I see this:

C1-CORE_OPTICS_SUM_DATA_ALL_TIME_0-1033801216-86400.png

So we need a factor of 5-10 increase in the electronics gain (why isn't the BS SUM on there?). This might be accomplished in the head, but for the ones with whitening boards, might be better to do there.

(** add to Jamie's list of long term tasks **)

  7581   Fri Oct 19 16:24:39 2012 ranaUpdateLockingAlignment is really bad??

 

 VENT NOW and FIX ALIGNMENT!

  7588   Mon Oct 22 11:26:12 2012 ranaUpdateSUS PITCH damping needed

 

Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.

  7609   Wed Oct 24 15:29:52 2012 ranaUpdateAdaptive Filteringmicrophone noise

  We have to change the sample rate and AA filter for the mic channels before going too far with the circuit design.

  7622   Thu Oct 25 10:03:38 2012 ranaUpdateAdaptive Filteringmicrophone noise

  That's no good - we need BLRMS channels for many PEM channels, not just two. And the channel names should have the same name as they had in the past so that we can look at long term BLRMS trends.

I suggest:

  1. Have a separate model for Mics and Magnetometers. This model should run at 32 kHz and not have low frequency poles and zeros. Still would have acoustic frequency BLRMS.
  2. Have a low frequency (f_sample = 2 kHz) model for seis an acc. Seismometers run out of poop by 100 Hz, but we want to have the ACC signal up to 800 Hz since we do have optical mount resonances up to there.
  3. Never remove or rename the BLRMS channels - this makes it too hard to keep long term trends.
  4. Do a simple noise analysis to make sure we are matching the noise of the preamps to the noise / range of the ADCs.
  5. Immediately stop using bench supplies for the power. Use ONLY fused, power lines from the 1U rack supplies.
  7635   Sat Oct 27 23:13:12 2012 ranaUpdateAlignmentalignment strategy

 Maybe we have already discarded this idea, but why not do the alignment without the MC?

Just lock the green beam on the Yarm and then use the transmitted beam through the ITMY to line up the PRC and the PZTs? I think our estimate is that since the differential index of refraction from 532 to 1064 nm is less than 0.01, using the green should be OK. We can do the same with the Xarm and then do a final check using the MC beam.

In this way, all of the initial alignment can be done with green and require no laser Goggles (close the shutter on the PSL NPRO face).

  7651   Thu Nov 1 01:51:37 2012 ranaUpdateAlignmentprogress, then setback - trend of BS table shift

  But these jumps in the OSEMs are all at the level of 10-20 microns. Seems like that wouldn't be enough to account for anything; 20 microns / (pend length) ~ 50-60 microradians.

  7660   Fri Nov 2 03:28:54 2012 ranaUpdateGeneralbronze bushing for 40m vac

Quote:

Suprema- SS clear edge mirror mount 2" diameter is modified for 40m vacuum use. One left and one right handed one. It's adjustment screw housing is bronze! It is not ideal for out gassing.

It will be baked and scanned. If it passes we should use it.

We may need these to bring out some pick-off beams.

 I vote against it. We don't know about the grease inside the screw bushings - scans are not everything if adjusting the screw loosens up the grease. If we need more pick off mirrors lets just make some of the kind that we already use inside for the 2" optics.

  7667   Sat Nov 3 10:31:59 2012 ranaUpdateAlignmentPOP, POX, POY, IPPOS, IPANG, REFL all coming out of vac

  That's good, but I request two things:

1) Check that the REFL beam is coming from the HR surface and not the AR surface. The real REFL beam should have as much power as the Faraday output. And where does the AR surface reflection go?

2) Use frame grabber to get as many images of the spot positions on the mirrors as is reasonable. Don't endanger bumping the tables again, but take what images can be gotten by remote camera views.

  7678   Wed Nov 7 07:11:10 2012 ranaUpdateAlignmentAlignment- POY and oplevs. photos.

The way to usually do image subtraction is to:

1) Turn off the room lights.

2) Take 500 images with no beam.

3) Use Mean averaging to get a reference image.

4) Same with the beam on.

5) Subtract the two averaged images. If that doesn't work, I guess its best to just take an image of the green beam on the mirrors using the new DSLR.

  7686   Wed Nov 7 23:22:45 2012 ranaUpdateAlignmentJamie's tip tilt proposal

 With Picos, we lose the ability to dither the input beam as well as align the beam with the IFO locked. And the active TT will still have hysteresis, but also actuators. Once in vacuum, I'm not sure how we adjust them - what's the error signal for PR2/PR3 ?

If the interferometer is aligned, why not just pump down now? I'm not sure that we have evidence of TT hysteresis issues once people stop touching them.

  7731   Tue Nov 20 11:40:19 2012 ranaConfigurationGreen LockingEnd table upgrade for auxiliary green laser : ETMX layout on new table

 

 Mounts:

  1. No more mounts using the 1" dia. pedestal / fork technology.
  2. No more mounts using the 1/2" post / post holder technology. Both of these are loose, weak, and cause noise.
  3. All steerable mirror mounts which carry the important sensing beams should use steel mounts (e.g. Polaris from Thorlabs). Aluminum mirror mounts are not to be used.
  4. The mounts must be mounted to a 3/4" steel post (these are the custom ones we used in the PSL; Steve should get some more of them made).
  5. The post is then mounted on an aluminum base (The BA2 or BA3 (2" x 3" aluminum) from Thorlabs is OK. The 1" x 3" ones are not). These must be fastened to the table using 2 screws, each with a SS washer.

 

  7739   Sat Nov 24 13:58:07 2012 ranaUpdateLSCcalibration of arms

For the loop diagnosis, its best to use the method of "IN1/IN2", rather than manipulate the close loop gain. In this way, you can directly plot the swept sine measurement from DTT as the open loop gain.

Also, for reporting calibration, we should all try to record the current settings better. Anything that may change the loop gain should be recorded along with the Bode plot and the DATA must be posted to the elog - no more of just posting plots.

We need to know, e.g.

  1. what is the power in the arms?
  2. are the LSC whitening filters on?
  3. are the SUS dewhitening filters on?
  4. What normalization is being used in the LSC?
  5. What digital filters are on in the X/YARM loop filter bank?

Resistance is feudal.

  7742   Mon Nov 26 10:06:51 2012 ranaSummaryIOOMC slides from 2002
Attachment 1: MCtalk.pdf
MCtalk.pdf MCtalk.pdf MCtalk.pdf MCtalk.pdf MCtalk.pdf MCtalk.pdf
  7758   Wed Nov 28 21:42:21 2012 ranaFrogsComputer Scripts / Programsdataviewer font error

An error this evening on rossa: dataviewer not working due to some font errors:

controls@rossa:~ 0$ dataviewer
Connecting.... done
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning: Not all children have same parent in XtManageChildren
Warning:
    Name: FilterText
    Class: XmTextField
    Character '\52' not supported in font.  Discarded.

Warning:
    Name: FilterText
    Class: XmTextField
    Character '\56' not supported in font.  Discarded.

Warning:
    Name: FilterText
    Class: XmTextField
    Character '\170' not supported in font.  Discarded.

Warning:

etc.............

  7768   Fri Nov 30 14:21:18 2012 ranaHowToComputer Scripts / ProgramsThe mystery of PDFs and you. As deep as the mystery of Rasputin.

This is how to post PDF:

From DTT, print the plot as a postscript file.

Then use ps2pdf to make a archival PDF version (the flag is the key!). Example:

ps2pdf -dPDFX /home/controls/Desktop/darm.ps

Attachment 1: darm.pdf
darm.pdf
  7773   Sat Dec 1 13:56:38 2012 ranaUpdateAlignmentBS chamber

 

 Whoever was working around the BS chamber at 11 AM on Friday should admit it now and take the punishment.

For those of you who like to do work on the interferometer without reporting it in the elog because you think that what you did doesn't affect anything, this is your example of how our time can be wasted by such laziness.

  7779   Tue Dec 4 01:43:37 2012 ranaUpdatePSLPMC calibration for MC_F calibration

  If you can't find the PMC sidebands in the transmission, its because the SNR is too small.

It may be a better idea to look at the PMC error signal, since the DC signal there is suppressed by the demodulation.

  7791   Wed Dec 5 09:42:46 2012 ranaOmnistructureComputersnew (beta) version of NDS2 installed on control room machines

NDS2 is not designed for non DQ channels - it gets data from the frames, not through NDS1.

For getting the non-DQ stuff, I would just continue using our NDS1 compatible NDS mex files (this is what is used in mDV).

  7792   Wed Dec 5 09:53:01 2012 ranaUpdateWienerFilteringThe microphones and the speaker on the AP table

  Don't try to re-invent the mic mount: just copy the LIGO mic mount for the first version.

  7796   Fri Dec 7 00:08:39 2012 ranaUpdateAlignmentc1ass

 

 This looks like a good performance tuning for these. It would be good if you can codify this procedure in the wiki so that even unexperienced people can tune up the system after reboots or vacuum work.

Is it possible to have some python scripts automatically measure and set the phases and matrices? If so, can we also run them iteratively so that after the second run we can confirm that they have converged? Then the script can output a short report of numbers telling us how well the system is now tuned.

I suppose that there is also a similar system possible to align the arms in a continuous way; i.e. low level drives and very low bandwidth. Also something fast / slow for the the DRMI.

  7802   Sun Dec 9 17:51:53 2012 ranaUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

 

 Some explanation of how you define power buildup please. Also some plots showing the evidence.

  7819   Thu Dec 13 01:49:53 2012 ranaUpdatePEMseismometers

Quote:

I've installed Guralp readout box back and it turned out that it does not work with voltage provided from the rack (+13.76 0 -14.94).  +/-12 voltage regulators inside the box convert it to -0.9 0 -12. I've connected the box to +/-15 DC voltage supply to measure seismic motion at the ETMY table. Readout box works fine with +/- 15.

Seismic noise on the ETMY table measured to be a few times higher then on the floor in horizontal direction in the frequency range 50 - 200 Hz. Attached are compared spectrums of X, Y and Z motions.

 Looking at the PEM BLRMS, I noticed that the GUR1Z channel had a much reduced microseism compared to the GUR1X. Looking at the BLRMS screens everything seems ON, although its a mess (too many filters in the banks, etc. - clean this up, PEM people).

 Looking at the Z channel in DTT, I see that the Z spectra looks double high pass filtered below ~1 Hz.     Needs some attention in the daytime.

From Den and Ayaka's elog entry from Nov 29, its clear that this problem is there at that time. It seems that the seismometer was not even hooked up before then. Perhaps Tara returned the seismometer around Thanksgiving and then someone here hooked it up but neglected to log this work? If so, please make an elog now describing the installation of this sensor at the 40m and log any future work which takes place at the 40m lab even if you think it is inconsequential.

Attachment 1: a.pdf
a.pdf
  7832   Fri Dec 14 09:31:59 2012 ranaUpdateLSCHigh frequency noise in AS signal

This is NOT calibrated. Its sort of calibrated in the 500-1000 Hz area, but does not correctly use the loop TF or the cavity pole.

As for the noise, remember that the whole point of changing the AS whitening gain was to turn on the whitening filter AFTER locking. With the WF OFF, there's no way that you can surpass the ADC noise limit.

Quote:

I calibrated the AS error signal into the displacement of the YARM cavity in the same way as I did before (elog).

  7841   Mon Dec 17 19:47:15 2012 ranaUpdatePEMSeismic StripTool config updated

I have updated the Seismic Striptool display which is plotted on the wall in the control room. Please take a look and make comments. We should finalize it and not change it anymore.

By having an unchanging display, we can get used to small changes in the seismic environment which disrupt our locking.

  1. y-scale is now linear; the log-scale was suppressing the factor of 2-3 variations which are important to us.
  2. Just as the rainbow does, the colors now go from red to purple to represent the noise from 0.1 - 30 Hz: the red traces are 0.1-0.3 Hz, the green/yellow traces are 0.3-3 Hz, and the blue/purple traces are 3-30 Hz.
  3. This is just showing GUR1. Let's try to keep this seismometer working so that we can have some long term record of the seismicity here. This means don't click off the buttons, disconnect the sensor, reboot the machine, etc. When you do do these things, elog them.
Attachment 1: SeismicRainbow.png
SeismicRainbow.png
  7844   Mon Dec 17 21:41:30 2012 ranaSummarySUSBeCu wire

Just in case we want to retrofit the Tip/Tils with Beryllium Copper wire, here are links to a few sources which have a supply of the right composition and temper:

http://www.lfa-wire.com/Tempered-Alloy-25_C17200.htm

http://www.alloywire.com/beryllium_copper_CB_101.html

http://www.ngk.co.jp/english/products/electronics/berylliumcopper/wire/index.html

http://www.goodfellow.com/E/Copper-Beryllium-Wire.html

 

I don't think its worth it to do something to modify them unless we get a real reduction in the hysteresis - need a benchtop test setup ASAP.

  7859   Wed Dec 19 20:18:51 2012 ranaUpdateComputersWe are Changing the Passwerdz next week----

Be Prepared

http://xkcd.com/936/

  7866   Thu Dec 20 19:46:20 2012 ranaConfigurationEnvironmentControl Room Projector

 Needs

StevePurple.JPG

  7873   Thu Jan 3 19:19:59 2013 ranaHowToElectronicscable racks

Today I found 3 power cables in the orange Pomona cable tray, put in so that the cables were damaged and therefore dangerous.

Please think about what you are doing before doing it. Damaging these things because your are in a hurry or frustrated will just waste our time and damage our interferometer.

For reference, we only use the thick blue Pomona racks for power cables. We use the orange and black ones for thinner cables. Pay attention and keep the cables organized.

Cable Rack Selection

 

  7875   Fri Jan 4 13:23:10 2013 ranaUpdateElectronicsPhotodiode transimpedance

You have to correct this transimpedance ratio by correcting for the different levels of DC photocurrent in the two devices.

For the dark noise, you must always include a trace showing the noise of the measurements device (i.e. the analyzer noise must be less than the dark PD noise) with the same input attenuation setting.

  7879   Mon Jan 7 19:23:19 2013 ranaUpdateElectronicsJamie's 1811 PS from 1998

  1. Front Panel switch supplies power, but does not light up - its unsafe as is. Needs new switch.
  2. Output has current limiting (which is nice) and schematic inside the box (which is very nice).
  3. Output voltage is not filtered or regulated ? LM7812 / 7912 would do the trick - or pick a PS with 18V outputs to reg down to 15 V.
  4. Box needs rubber feet.
  5. Overall B-

Also, we still need to get a 32GB SD card for the new camera. It only has an 8GB one.

Attachment 1: SOLA-1021-1026.pdf
SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf SOLA-1021-1026.pdf
Attachment 2: jamie98.jpg
jamie98.jpg
  7900   Tue Jan 15 01:41:40 2013 ranaUpdateSUSTT

 That seems like easily enough range; as long as we can put the TT into the middle of their range to start with we should be OK.

We should consider instrumenting the leakage transmission through all TT with a bare QPD on a stick. We can then use those sensors to monitor the spot positions within the input mirrors as well as the PRC / SRC.

  7909   Wed Jan 16 20:27:16 2013 ranaUpdateLockingExpected PRC gains

Why would we use such a bad optic in our recycling cavity? Is 1.5% the spec for these mirrors? Is this the requirement that Kiwamu calculated somehow? Did anyone confirm this measurement?

I can't believe that we'll have low noise performance in a RC where we dump so much power.

  7921   Sat Jan 19 16:02:28 2013 ranaOmnistructureElectronicsPS cleanup

During our 'Women in Physics' tours today, we were reminded that there are several bench power supplies being used as permanent inside.

Some are being used to power PZTs, AOMs, VCOs, RFPDs, etc. On Wednesday, after the meeting, we will all go inside and remove one and replace it with a fused, professional wiring to the rack power supplies. The temporary ones must be removed.

  7922   Sat Jan 19 18:23:31 2013 ranaUpdateComputersAll front ends but c1lsc are down

After sshing into several machines and doing 'sudo shutdown -r now', some of them came back and ran their processes.

After hitting the reset button on the RFM switch, their diagnostic lights came back. After restarting the Dolphin task on fb:

"sudo /etc/init.d/dis_networkmgr restart"

the Dolphin diagnostic lights came up green on the FE status screen.

iscex still wouldn't come up. The awgtpman tasks on there keep trying to start but then stop due to not finding ADCs.

 

Then power cycled the IO Chassis for EX and then awtpman log files changed, but still no green lights. Then tried a soft reboot on fb and now its not booting correctly.

Hardware lights are on, but I can't telnet into it. Tried power cycling it once or twice, but no luck.

Probably Jamie will have to hook up a keyboard and monitor to it, to find out why its not booting.

FE.png

P.S. The snapshot scripts in the yellow button don't work and the MEDM screen itself is missing the time/date string on the top.

  7943   Thu Jan 24 16:34:56 2013 ranaUpdateGeneralLaseroptik mirror - SN6

  I have two questions:

1) Are we sure that the T measurement is not being compromised by some systematic? i.e. some leakage is making the apparent T appear too high.

2) IF the T is really so high, how should we decide whether or not to use this one rather than the G&H? Is the 532 nm property more important than the high recycling gain?

  7979   Thu Jan 31 22:14:11 2013 ranaSummaryASCOptics lit

 Gouy not Guoy:

http://www.rp-photonics.com/gouy_phase_shift.html

pronounced Goo-eee, with the emphasis on the second syllable.

  7988   Fri Feb 1 23:52:59 2013 ranaUpdateLockingPRM/PR2 cavity

 Very exciting result, if true. I suppose we should try to reconfirm this result by doing another phase map of PRM03.

Is it possible that PR2 is not flat? How would we test to see if the tip-tilt frame screw gives it a curvature? Perhaps we can check with COMSOL.

  8015   Wed Feb 6 19:59:35 2013 ranaUpdateLockingPRC cavity gains

  Getting closer, but need to use the real measured AR reflectivity values, not the 1500 ppm guess. These should be measured at the correct angles and pol, using an NPRO.

  8029   Fri Feb 8 00:23:33 2013 ranaSummaryGeneralPRC/arm mode matching calculations

 

 I would guess that either flipping PR2 or PR3 would give nearly the same effect (g = 0.9) and that flipping both makes it even more stable (smaller g). But what we really need is to see the cavity scan / HOM resonance plot to compare the cases.

The difference of 0.5% in mode-matching is not a strong motivation to make a choice, but sensitivity to accidental HOM resonance of either the carrier or f1 or f2 sidebands would be. Should also check for 2*f2 and 2*f1 resonances since our modulation depth may be as high as 0.3. Accidental 2f resonance may disturb the 3f error signals.

  8051   Sat Feb 9 19:34:34 2013 ranaUpdateOpticsG&H - AR Reflectivity

 

 Use the trick I suggested:

Focus the beam so that the beam size at the detector is smaller than the beam separation. Use math to calculate the beam size and choose the lens size and position. You should be able to achieve a waist size of < 0.1 mm for the reflected beam.

  8096   Sun Feb 17 19:27:19 2013 ranaUpdateSUSPRM coil balanced

 I will check out the AS55 situation tomorrow. Just put it on my desk.

MC Autolocker was disabled - I enabled it.

For the F2P.py, you should look at how we did this with the script written 8 years ago in csh. There we stored the initial values in a file (so they don't get blow away if someone does CTRL-C). Your python script should have a trap for SIGINT so that it dies gracefully by restoring the initial values. In order to have the smooth value adjustment, you must first set the TRAMP field for all the coil gains to 2 and then switch. Make sure that the lockin ignores the first few seconds of data after making this switch or else it will be hugely biased by this transient.

For the PRM OL use as a F2A reference, you also have to take into account that the OL beam is hitting the PRM surface at non-normal incidence. IF it is a large angle, there will be a systematic error in the setting of the F2Y values.

ELOG V3.1.3-