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ID Date Author Type Category Subject
8738   Mon Jun 24 16:06:17 2013 ManasaSummaryGreen LockingALS model

I am working on the basic ALS servo model. The simulink model for the same is attached. The loop is not yet complete (I'm still debugging it) ; but this is just an update of where I am right now.

Attached is the simulink and matlab file.

Attachment 1: elog.zip
8737   Mon Jun 24 11:51:23 2013 JenneUpdateLSCNew modeled sensing matrix

 Quote: This is nice - how about figuring out how to plot the measurement and model on the same plot? I guess we need to figure out how to go from counts to Watts.

I haven't done a units conversion for the measured vs. modelled plot,  but at least we can compare the separation between the different degree of freedom signals.  Figuring out why the REFL11 measurement and models are so different is still high on my to-do list.  But at least the measurements that were taken last month are consistent with one another. EDIT:  The separation angles match up pretty well between the 2 sets of measurements, but the overall rotation isn't really consistent.  I do not believe that the phase rotation values that we're using online changed between the measurements, so the I&Q lines should be the same for both seets of measurements....however, I did not write down the phase rotation values at the time of the first measurement, so there's a chance that they were different.  Also, something that I need to monitor is the coherence of my measurement, to make sure I'm really driving and measuring something.

2 measurements, with overall rotation arbitrarily rotated to make MICH lines match up:

Same 2 measurements, without the arbitrary overall rotation:

Measurement vs. Model, with the *modelled* phase arbitrarily rotated:

8736   Fri Jun 21 16:30:04 2013 SteveUpdateGeneralCapacitor Inventory

The 3 Panasonic Ceramic Kits Books, 1206 NPO, SMT are well stocked. The 4 th one needs to be refilled at some values.

I labeled them on the cover for fast access. See Atm1

The Metalized Polyester Film Book with through holes mount are in good shape also. Atm2

The AVX Ceramic 1206,  Garrett cab, range: 1pF - 22 microF 50V...... 67 values

Note here: that the value of dielectric, capacitance / voltage will vary

NPO: 1 pF - 1 nF /  50V .......37 values

X7R : 1 nF -  0.082 microF /  50V,  0.1 microF /  100V.......27 values

Y5V:  4.7 microF / 6.3 V,  10 microF / 10V,  22 microF / 6.3V.........3 values

Attachment 1: CeramicCaps1206NPOsmt.jpg
Attachment 2: PolyesterFilmCapThroughHole250VDC.jpg
8735   Thu Jun 20 20:46:16 2013 gautamUpdateIOOWFS debugging-QPD debugging

I wanted to make sure that the QPD map on the C1IOO_MC_TRANS_QPD.adl screen corresponded to the actual physical quadrants on the photodiode at the MC2 table. We turned MC_WFS_OUT  OFF before fiddling around with a red laser pointer to try and map the quadrants.

I initially verified the correspondence between the various quadrants and the text-fields displaying the outputs using PV_Info. I found that there was good agreement in this respect. So for instance, field adjacent to the quadrant marked "1" on the C1IOO_MC_TRANS_QPD.adl screen had the following input channel: IOO_MC_TRANS_SEG1_INMON. The filter banks were empty and there was just an overall gain on -1 on all four channels. The channels leading to the filter-banks were the 'right' ones: quadrant 1 for the top bank, then quadrants 2,3 and 4 down.

Next, a red laser pointer was used to map the quadrants. Here, there was some disagreement between the physical quadrants and the map on the C1IOO_MC_TRANS_QPD.adl screen, which is summarised in the attached image-the whole thing is sort of rotated 180degrees about the centre.

The interpretation of the figure is as follows:

MC_WFS_OUT was turned back ON.

8734   Thu Jun 20 17:47:44 2013 AnnalisaConfigurationSUSETMY oplev servo

[Jenne, Annalisa]

The ETMY Oplev servo didn't work properly, when it was activated the ETMY moved too much.

We measured the oplev TF for Pitch and Yaw and it turned out that the gain was too low by a factor 3, so we increased the gain from -.250 to -.750 on both.

We also locked the Y arm and we could see that the mirror's oscillations are actually suppressed.

8733   Thu Jun 20 15:15:39 2013 ranaUpdateIOOWFS debugging

Tried a bunch of stuff, but eventually just turned off the TRANS_QPD loops and loops are stable. Needs more debugging.

1. Modified the on/off scripts so that the Integrators are no longer toggled. No reason to turn them off since we are clearing the filter bank histories.
2. With QPD feedback OFF, I have lowered the overall gain by 15x so that its just drift control.
3. Deleted unused / bad filters from the main filter banks.
4. Gautam is going to debug the QPD with a red laser pointer and then elog.
5. Jamie is checking out the MC Coil dewhitening logic to see if that's in a funny state.
Attachment 1: Untitled.png
8732   Thu Jun 20 09:33:42 2013 SteveUpdateGeneralcleanup

Office work benches were cleaned up yesterday. Anti-image filter boards were moved to north wall of the control room. Koji's pd- electronics box  placed next to water dispenser.

The removed ETMY optical table: TMC 4' x 2' x  4" with Aluminum enclosure was placed on table in the east arm.

Attachment 1: tmc3x2.jpg
8731   Thu Jun 20 01:13:18 2013 JenneUpdateLSCPRCL locking again - no ASC success

I didn't have any success with the ASC tonight.  I copied over the filters that Koji had used in elog 8562, and put them in the new ASC filter banks (and turned them off in the SUS-PRM_ASCYAW bank).  I also moved all the old scripts that were in .../scripts/ASC to an OLD subdirectory (the most recent edit is from 2009 sometime).  I then copied over the up and down scripts that Koji had written for his ASC test into the ..../scripts/ASC directory, and modified them to work with my new channels.

I then tried locking, and wasn't very successful.  Actually, my best lock, ~4 minutes, including tweaking up the PRM alignment, was when the ASC path was off (even though I thought it was on).  After discovering my mistake, I tried locking for another hour or so, but haven't really gotten anywhere.  The lock stretches I'm getting are rarely long enough for me to get to the terminal and run my up script, and the maybe ~6 or 7 times I've been able to run it, I haven't converged toward finding a good gain value for the PRC yaw loop.  At some point, I redid the MICH alignment since it had drifted away a bit, but that didn't really help.

I think that one of the next things I might try is carrier-locking the PRMI, to find okay loop gain settings for the ASC path.  Since the QPD output is already normalized (I'd have to custom-make some electronics to make it non-normalized), I think the gain should be the same for both carrier and sideband lock cases.

_______________________________

Once I finally get a good, stable, PRMI sideband lock, I think I need to take the following measurements:

* CTRL and ERR spectra for MICH and PRCL

* TFs for MICH and PRCL loops

* Sensing matrix, including AS55, REFL11, REFL33, REFL55, POX and POY.

---->> Are there any others?

8730   Wed Jun 19 23:50:44 2013 JenneUpdateLSCPRCL locking again

This is a mid-evening update, so I don't forget all the stuff I've already done.

Aligned PRMI, no nice flashes on POP110.  Aligned and locked PRM-ITMY half-cavity on the carrier, and used that POP beam to center the beam on the POP110 PD.  I also turned on the new QPD and centered the beam on it.

Notes about QPD setup:  The "zero/cal" switch is OFF, so none of the small knobs on the front (basically, everything but the gain knob) should be bypassed.  The gain knob is set to position 3.  This is the highest gain that I can have without the "too much light" saturation light blinking on the front panel.  (During this time, POP110I is flashing around 200 counts).

I made a super hacky ASC screen, which is accessible from the ASC button on the sitemap.  While there is a pitch path in the model, I only put in the yaw elements (except for the QPD readouts) in the screen, since that's what I'll be using for now.

I added filter banks to the front side of the ASC subblock in the ASS model, so that I have a place to monitor the QPD signals on the screen and with striptool.

Using the settings that Koji recorded in elog 8521 in the "Locking with SQRT(POP110I)" section (and no ASC engaged so far), I can lock the PRMI for ~10 or 20 seconds, at 150 or 200 counts on POP110I.  So, I'm doing well so far, and next up is to copy the ASC filters Koji made in elog 8562, and try the new ASC.

8729   Wed Jun 19 22:38:15 2013 JenneUpdateComputer Scripts / ProgramsLSC normalization sqrt_mon channels added to conlog

Something has happened that all of the C1:LSC-dof_NORM_SQRT_ENABLEs are disabled, but normally some are enabled and others are not.

In the hopes that miraculously this change happened after Jamie restarted the conlog this afternoon, I checked the conlog.  These channels, however, were not recorded.

Using the instructions on the conlog wiki page, I added the _MON channels to the conlog list.  The one snag I hit was that the medm screen referred to in the wiki isn't usable if you open it by hand using the medm gui, since it needs to know what IFO you're at to fill in the macro expansion variables.  To remedy this, I changed the "FE STATUS" button on the sitemap to "CDS", and added the conlog screen to the list of options.

Now I see that the conlog at least knows about these channels, for future reference.

8728   Wed Jun 19 22:02:03 2013 JenneUpdateASCNew POP path - ready to try

I put the POPDC cable back to the DC output of the bias tee that is the first thing at the LSC rack that the POP110 PD sees.  So, now we should be back to the old nominal PRCL locking, with the addition of the new QPD.

I'm going to give it a whirl.....

8727   Wed Jun 19 18:24:14 2013 JenneUpdateCDSProto-ASC implemented in ASS model

I have implemented a proto-ASC in the ASS model.

In an ASC block within the ASS model, I take in the POP QPD yaw, pit, and sum signals.  I ground the sum, since I don't have normalization yet (also, the QPD that we're using normalizes in the readout box already).  The pit and yaw signals each go through a filter bank, and then leave the sub-block so I can send the signals over to the SUS model, to push on PRM ASCPIT and ASCYAW.

In doing this, I have removed the temporary PRM ASCYAW connection that Koji had made from the secret 11'th row of the LSC output matrix (see Koji's elog 8562 for details from when he implemented this stuff).

LSC, SUS and ASS were recompiled, and restarted.  I also restarted the daqd on the fb.

8726   Wed Jun 19 16:47:34 2013 JamieConfigurationComputer Scripts / Programsconlog startup fixed, and restarted

 Quote: I cleaned up a bunch of conlog stuff to make it all a little more sane and simple.  I also fixed the messy startup shenanigans, so that it should now start up sanely and on it's own (using Ubuntu's native upstart system).  The conlog wiki page was updated with all the new info.

By the way, I also did confirm that it is running and registering EPICS changes.

8725   Wed Jun 19 16:04:56 2013 JamieConfigurationComputer Scripts / Programsconlog startup fixed, and restarted

I cleaned up a bunch of conlog stuff to make it all a little more sane and simple.  I also fixed the messy startup shenanigans, so that it should now start up sanely and on it's own (using Ubuntu's native upstart system).  The conlog wiki page was updated with all the new info.

8724   Wed Jun 19 15:07:20 2013 ranaUpdateIOOWFS debugging

Trying to figure out what's wrong with the MC WFS:

1) The symptom seems to be that the control signals become very large in the pitch and then the loop breaks when they saturate. Usually this is due to a degenerate matrix or improper inversion. Most likely some of the BURT restore is bad or the analog gain for one of the WFS has been switched when Jamie was doing the "Guardian" debugging.

2) In checking this out, I found that several buttons on the WFS  screens were not working (and apparently have never been working). Please try to test things in the future...The filter bank buttons in C1IOO_MC_TRANS_QPD were using relative path names; fixed these to use abs path names. The buttons in the WFS_MASTER for the IOO_PIT banks were using IOO_PITCH instead...

2.5) Recentered beams on WFS heads with MC alignment good and MC unlocked.

3) Main problem in the WFS still not found - disabling this in the autolocker.

8723   Wed Jun 19 04:56:07 2013 KojiUpdateASCmodel name ASS -> ASC ???

Sounds good.
Or we just stuff any angle control things in to Angular Stabilization System without changing the model name.
The process name itself is not a big deal.

8722   Wed Jun 19 02:46:19 2013 JenneUpdateCDSConnected ADC channels from IOO model to ASS model

Following Jamie's table in elog 8654, I have connected up the channels 0, 1 and 2 from ADC0 on the IOO computer to rfm send blocks, which send the signals over to the rfm model, and then I use dolphin send blocks to get over to the ass model on the lsc machine.

I'm using the 1st 3 channels on the Pentek Generic interface board, which is why I'm using channels 0,1,2.

I compiled all 3 models (ioo, rfm, ass), and restarted them.  I also restarted the daqd on the fb, since I put in a temporary set of filter banks in the ass model, to use as sinks for the signal (since I haven't done anything else to the ASS model yet).

All 3 models were checked in to the svn.

8721   Wed Jun 19 01:45:49 2013 ManasaUpdateGreen LockingBeat frequency sweep for 3FSR

Measurements:

1. Calibrating offset :

I measured the shift in the beat frequency while scanning through the offset. Offset stepped by 50 resulted in 1MHz shift of the beat frequency.

2. Anti-whitening filter for beatbox output:

I made an anti-whitening filter for the beatbox output in the ALS_BEATX_FINE_I module by inverting the whitening filters that Jamie had installed in the beatbox earlier (elog).  I have kept the old anti-whitening filter in the module as well for the time-being because the new anti-whitening filter was not as good as the old one in stabilizing the servo (large error signals and unstable ALS).

3. Beat frequency scan for 3FSR:

With ALS loop enabled, I did an offset sweep corresponding to 3FSR (FSR = c/2L = 3.7MHz). The loop doesn't seem to be stable enough to reduce the arm fluctuation to get a resonance for IR. Time series of scan is shown below:

4. No-loop and in-loop spectrum:

I measured the spectrum of the error signal (C1:ALS-BEATX_FINE_I_IN1) with ALS loop enabled and disabled. To suppress the peaks at 3.2Hz and 16.5Hz, I turned ON the corresponding filters. I have recorded the error signal spectrum with only 16.5Hz res gain filter turned ON. Turning ON res gain 3.2Hz filter kicked ETM.
Spectrum of error signal shown below:

To resolve:

1. What is wrong with the new anti-whiteing filter?

2. Why would the res gain filters kick ETM and show no noise suppression?

8720   Wed Jun 19 01:12:42 2013 JenneUpdateASCmodel name ASS -> ASC ???

I am proposing a model name change.  Currently, we have an "ASS" model, but we do not have an "ASC" model.

The ASS is currently using ~17 of 60 available microseconds per cycle.  So, we have some cpu overhead available to put more stuff on that cpu. Like, say, ASC stuff.

So, my proposal is that we change the ASS model name to "ASC", and put all of the ASS-y things in a top_names block, so we retain the current channel names.  The IOO top_names block that is in the current ASS model (which is there to send signals to the LSC DAC for the input tip tilts, even though the names need to be IOO) should obviously stay on the top level, so that things in there retain their names.

Then, I can make a new top_names sub-block for ASC-like things, such as the new POP QPD.

Inside the ASC block (in the ASC model), I'm currently thinking something simple will do..... QPD inputs, going to a matrix, which outputs to the filter banks in the "length" degree of freedom basis (PRCL, SRCL, etc), then another matrix, going to the ASC suspension paths.

So, for example, the POP QPD pitch would go to the PRCL_PIT filter bank, and then on to the PRM_ASCPIT path in the SUS screen.

Or, in another example case, IPPOS yaw would go to an input pointing filter bank, then on to TT1's yaw slider.

EDIT:  After a few minutes of thinking, I think I also want triggering, and perhaps filter bank triggering, in the ASC model.  One of the reasons Koji has been pushing for the new automation system is that when the PRC fell out of lock, the ASC path would kick the PRM until Koji ran a down script.  Triggering will fix this issue, and it's the kind of thing that needs to happen quickly, so may not really be appropriate for the Guardian anyway.

8719   Wed Jun 19 00:46:06 2013 JenneUpdateSUSsave/restore alignment scripts now also work for TTs, fixed a bug

I have done a quick update of the IFO_ALIGN screen's save and restore scripts, so that we can now also save, restore, and view the saved values for the input tip tilts.

In the past, there was an "if" statement to check if the optic was a PZT, and if so, define the alignment channels accordingly (since all the SOS suspensions have the same format for the name, and the PZTs were the odd ones out).  I have removed the mention of PZTs, and replaced the if statement with an "if TTs" statement, and put in the correct channel names (C1:IOO-TT#_PIT_OFFSET, and the same for YAW).

Also, I caught a bug in the code, which explains some confusing behavior that I had seen in the past.  When deciding if the restore script should take small steps or just do a big step, it looked at the difference between the saved value and the current value of the slider.  It was *not* looking at the absolute value of the difference.  So, if you had misaligned a slider by hand, and it was in the opposite direction of what the misalign script does, the restore script wouldn't realize that the optic needed to be restored in small steps.  I have now fixed this bug for both pit and yaw cases of the restore script.

8718   Tue Jun 18 18:24:07 2013 ManasaUpdateIOOMC WFS turned OFF

[Jenne, Jamie, Manasa]

After this, I received the MC locked in TEM00 with MC_REFL at ~2.5 counts from Jamie. Usually the WFS would do their job in this case to bring MC to a good locking condition and since this did not happen, I figured out that something was wrong with the MC_WFS.

What we did:

1. The WFS were turned off.

2. As a first step, we wanted to run the WFS_OFFSET script (Koji's elog) which requires MC to be locked with MC_REFL<0.5 and spot positions centered. The autolocker was disabled and MC locked manually to MC_REFL<0.5.

3. While running the WFS_OFFSETS script, Jamie pointed out that the inputs to the WFS servo had been turned off. After the WFS_OFFSET script finished running we turned ON the WFS inputs.

4. Following this, the MC was relocked manually and MC spot positions were measured (all spot positions were decentered by < 2 mm).

5. We ran the WFS_OFFSET script again and turned the WFS back ON. But this would still kick the MC out of lock.

Status: MC is locked with WFS turned OFF. Jamie will be looking through what changes he had made earlier today to fix this problem.

8717   Tue Jun 18 10:37:00 2013 SteveSummaryGeneralnew laser pointers

Red-green laser pointers added to the depleted stock of 2011

The two pointers output measured 4.4 mW green and 2 mW red

8716   Tue Jun 18 07:22:20 2013 KojiUpdateLSCSensing Matrix vs. Schnupp Asymmetry

Interesting.
What's the reason why the PRMI/MICH ratio gets worse (larger) for 55MHz and 165MHz for the DRMI compared to the PRMI case?

8715   Mon Jun 17 23:53:03 2013 AnnalisaUpdateGreen LockingY arm locked on green!!

## Y arm locked on green carrier in 00 mode!

It locked at almost 280 cts, and the transmitted power on the PSL table is  about 40 uW.

To make it lock on the carrier I had to flip the sign of the error signal in the PDH loop, so I put a phase shifter (a Pomona box with a 23 uF capacitor) right before the LO input of the PDH box (on the model of the X arm).

Tomorrow I will put more details about the power budget and the phase shifter transfer function.

8714   Mon Jun 17 23:12:19 2013 ManasaUpdateGreen Lockingcan't get IR to resonate

What I did:

1. Followed the same procedure to enable ALS (http://nodus.ligo.caltech.edu:8080/40m/8703)
2. Enabling ALS servo stabilized the arm fluctuation and the beat frequency.
3. Beat frequency sweep was done (with ALS servo enabled) by changing offset C1:ALS-BEATX_FINE_OFFSET_OFFSET in steps.

Discussion:

I swept the beat frequency through ~10MHz and could not find IR resonance. But TRY TRX varied from 0 - 0.9 counts as the beat frequency sweep was done. I suspected that the offset steps might have been too big and I had jumped over the IR resonance. So, I repeated the offset sweep again in smaller steps (offset steps 0.1) and it did not help.
I also played with the gain of the ALS servo to stabilize the loop and set the gain to the maximum (smallest error signal oscillating around '0') and did the frequency sweep. The arm cavity would still not resonate through the sweep but only evolve from no flashes to strong flashes for IR (0 - 0.9 counts).
8713   Mon Jun 17 21:10:25 2013 JenneUpdateLSCSensing Matrix vs. Schnupp Asymmetry

The plots, with a log y axis

PRMI:

DRMI:

PRFPMI:

DRFPMI:

8712   Mon Jun 17 17:51:43 2013 JenneUpdateLSCPOP QPD cables laid

Power not on to the POP QPD yet though.  Also, still need to reconnect POPDC.

8711   Mon Jun 17 16:34:15 2013 JenneUpdateLSCSensing Matrix vs. Schnupp Asymmetry

I have made some plots of the sensing matrix (PRCL / MICH amplitude ratio, and relative angle) versus Schnupp asymmetry for all the configurations that involve the power recycling cavity.  I am still meditating on what they mean for us, in terms of whether or not we should be changing our Schnupp asymmetry.

The Schnupp asymmetry scan starts at 1mm, rather than 0.  Also, recall that our current Schnupp asymmetry is 3.9cm.

PRMI:

DRMI:

PRFPMI:

DRFPMI:

8710   Fri Jun 14 17:54:11 2013 JenneUpdateASCNew POP path - cabling work

 Quote: ... I need to ... lay some cables between the supply/readout box and the IOO chassis (where Jamie has freed up some channels for me).

I have made 3 dongles that go from 2-pin lemo to BNC so that I can connect the 3 QPD signals (X, Y, Sum) to the IOO ADC (Pentek Generic board in 1Y2, which also has the MC channels).

The interface board with the 2-pin lemo connectors doesn't have anything in the DCC for the document number (D020432), so I asked BAbbott, and he said: "After a bit of searching, I found that on psage 2 of D020006-A-pdf ( https://dcc.ligo.org/LIGO-D020006-x0 ), Pin 1 of each LEMO connector is the + leg, and pin 2 is the - leg.  This means that you should connect the center conductor of the BNC (if you don't have any 2-wire twisted-pair cables around) should be connected to pin 1 of the LEMO, and the outer conductor should be connected to Pin 2.  According to http://il.rsdelivers.com/product/lemo/epg0b302hln/2-way-size-0b-pcb-mount-socket-10a/1305621.aspx Pin one is the top one on the right-angled LEMO."  According to page 50 of the lemo data sheet, pin1 is the one with the mark next to it, when you are looking at the solderable end.

8709   Fri Jun 14 17:15:45 2013 ManasaUpdateGreen Lockingc1als model edited

I have edited the daq channels in c1als model.

Added: DQ channels for the error signal (phase tracker output)
Removed: DQ channels that existed for the beat_coarse signals

Installed and restarted the model on c1ioo.
Frame builder restarted.
Changes were committed to the svn.

8708   Fri Jun 14 07:06:19 2013 KojiSummaryGreen LockingX arm ALS

It's nice that we are now able to scan the cavity again. We got close to PRMI+one arm one step further.
The calibration of the scan frequency and the evaluation of the in-loop/out-of-loop error signal in terms of (Hz/rtHz) would be necessary.

The beat amplitude looks actually huge aIthough I don't know where you are monitoring.
Talk to Jamie to figure out how much the signal should be at the monitoring point.
If it is more than we are supposed to have, put an attenuator somewhere.

8707   Fri Jun 14 03:10:40 2013 JenneUpdateASCNew POP path - PDs in place, need cabling

I have placed the lenses and the PDs in their new positions on the POP path.  As Koji had pointed out to me in reply to elog 8663, what really matters to get the beam size I want on the QPD is the distance between the lenses, and not so much the absolute position of the lenses (since the Rayleigh range of the POP beam coming out of the vacuum is so long), so I left the 2" lens in place, and made the distance between the Y1 and the QPD's lens 35 cm.

I didn't move the camera very much, mostly just enough to get the beam centered on the TV.  I need to check where this is in terms of the beam shape, to see where I should move it to, so that I'm getting useful beam motion information by looking at the camera.

The steering mirror for the POP110 PD is still between the camera and the steering mirror for the QPD, there's just much less space between those 3 elements than there was previously.  I put the POP110 PD's lens and the PD itself in such a way that the PD is at the focus.

The PD which used to be the ASC razor blade PD has been put back in the cabinet.  The cable that was plugged into it was being used for POPDC.  I will need to switch things back so that POPDC is once again coming from the POP110 PD.  Also, I need to bring over the power supply for the QPD, and lay some cables between the supply/readout box and the IOO chassis (where Jamie has freed up some channels for me).

Also, while I was on the POX table, I was reminded that we need to deal with the ITMX oplev situation, which Gautam detailed in elog 8684.  I will ask Steve to take care of it when he's back from vacation.

8706   Fri Jun 14 02:38:07 2013 ranaUpdateLSCNew modeled sensing matrix

This is nice - how about figuring out how to plot the measurement and model on the same plot? I guess we need to figure out how to go from counts to Watts.

8705   Fri Jun 14 00:32:43 2013 JenneUpdateLSCNew modeled sensing matrix

I put in a new version of the modelled plot.  I figured out a different way to keep things generic so the same script can be used for other sites, but writes the names in the same format as the measured matrix, so the correct order is preserved.

The REFL11 measurement is consistent with the one in elog 8648 (data taken a few days earlier), within the error bars.  My goal for tonight is to hopefully get the POP path back in order, so that I can lock the PRMI again, and can measure again if I want.

The error bars for each sensor are only taken once (with no drive, so it's the noise in the "dark" sensor).  I take 6 "dark" measurements for each sensor, and get the stdev.  Then I use that and propagate it through for each measured sensing matrix element.  So, the PRCL and MICH error bars for REFL11 were created from the same standard deviation, and propagated in the same way, but the values plugged into the partial derivative of the function were different for PRCL and MICH.

$s_f = \sqrt{ \left(\frac{\partial f}{\partial {x} }\right)^2 s_x^2 + \left(\frac{\partial f}{\partial {y} }\right)^2 s_y^2 + \left(\frac{\partial f}{\partial {z} }\right)^2 s_z^2 + ...}$(wikipedia - propagation of uncertainties)

Also, to answer an emailed question via the elog, the "0 degree" axis of the plots is the 0 demod phase axis, which corresponds to the I output of the demod boards (the I input to the RFPDs, before the phase rotation).  The "I" axis that I've drawn is the current demodulation phase that we have, which corresponds to the I_ERR output of the RFPDs after the phase rotation, which is the PD_I signal that goes into the LSC input matrix.  I draw this to help us see if our current demod phase is well tuned or not.

Yes, the MICH and PRCL signals are not at all orthogonal in the REFL33 sensor.  I think this is because our modulation frequency was chosen to be good in the case of the full DRFPMI IFO, not the corner IFO cavities.  As I calculated in elog 8538, the ideal frequency for the PRMI is 18kHz larger than our current modulation frequency.

For the plots below, note that 11.066134 MHz is our current actual modulation frequency, and 11.0843 MHz is my calculated ideal modulation freq

Model, using our current modulation frequency, and the designed PRCL cavity length (same as elog earlier today):

Model, using the "ideal" PRMI modulation freq, and the PRCL cavity length used in elog 8538, where I calculated that number (a few cm different than the design PRCL length):

You can see that if we could use a better frequency, we would get much, much better signal separation.  Since our modulation frequency choice is related to our vacuum envelope constraints (we can't make the arms of a length that will have the sidebands exactly antiresonant when the arms are locked on the carrier), I hope that this will not be a significant issue in aLIGO.

8704   Thu Jun 13 23:28:40 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching

Quote:

 Quote: After restoring alignment I could see again strong 00 flashes (about 250-300 counts on ALS-TRY). So I locked the arm with IR and after enabling the PDH servo for the green locking, I also locked the green on the Y arm in 00 mode. Then I moved the two mode matching lenses to maximize the power into the 00 mode, but I didn't reach more than 30-35 counts. Green power injected into the Y arm                    0.680mW Green power reflected back                                  0.090mW Green power transmitted on the PSL                  few uW I would expect more power on the PSL table (maybe 10x more).

Is this reflection measured with the cavity locked or unlocked?

So what's the actual designed reflectivity of the ETM for green? No one seems to be able to give me a straight answer about this.

Looking at the reflected beam when the beam is misaligned makes it look like it's << 0.9. Is that expected given the coating spec?

You say the cavity scan goes as high as 300cts but you can only lock to 30cts, are you locked on the sideband?

-The reflection is measured when the cavity is unlocked. I measured it with the power meter in front of the PD, so I interrupted the PDH loop.

- From the specs of ETM we have:

T(S1,HR,532nm)=5.0%+/-3% (+/-1% target),  R(S2,AR,532nm)<1000ppm

It means that I should have about 600-550 uW in reflection, but I don't. I can say that there are many losses, and maybe some power is clipping inside the Faraday. Nonetheless, the reflected beam looks less strong than the injected one, so most of the losses should be on the ETM table.

(- The reflected power is 0.090 mW, I just wrote it wrong yesterday, sorry!)

- The last question is actually very interesting. Maybe I was locking on the sideband when I locked to 30 cts, but if it is the case I cannot really explain why today I locked on the carrier (I locked the cavity to about 200-250 cts), and everything I changed was the PD gain and the amplitude on signal generator connected to the PDH box. It seems like there should be some sign flip somewhere, but I need to think about.

8703   Thu Jun 13 22:31:12 2013 ManasaSummaryGreen LockingX arm ALS

Stabilized ALS and beat frequency sweep realized.

Procedure:

1. Enable appropriate filter modules and set appropriate servo gains.

 Servo module Filters Gain C1:ALS-BEATX_FINE_I FM2 FM3 1.0 C1:ALS-BEATX_FINE_Q FM2 FM3 1.0 C1:ALS-BEATX_FINE_PHASE FM1 300.0 C1:ALS-BEATX_FINE_OFFSET - 1.0 C1:ALS-XARM FM4 FM5 -0.25 C1:ALS-ETMX - 1.0

2. Clear history of C1:ALS-BEATX_FINE_PHASE

3. Enable the servo loop. I had set limits on the servo loop and ramp time for gain switching so that I don't kick the ETMY hard.
Gains were decided such that the error signal C1:ALS-BEATX_FINE_PHASE_OUT was minimized.

4. Beat frequency sweep is realized by stepping up on C1:ALS-BEATX_FINE_OFFSET_OFFSET (from 0 to 2100 in this case).

Video1 shows the difference that can be seen at the RF spectrum analyzer when ALS is enabled.

Video2 shows the beat frequency sweep as seen on the spectrum analyzer.

I could not get 'getdata' to work as I wanted. So I have attached the error signal trend before and after the ALS servo loop is enabled.

Thank you Jenne for helping retrieve more sensible data!

The beat note is very strong and we can clearly see its harmonics as well. Attached is the picture showing the several harmonics.
________________________________
Peak frequency(MHz)    Power(dBm)
________________________________
47                                    -2.77
93.5                                -27.56
139                                 -32.75
185.4                              -45.64
231.9                              -57.10
278.4                              -59.42
________________________________

To do:
1. Obtain IR resonance.
2. Check the digital anti-whitening filter after the beatbox.
3. The effect of the harmonics should be figured out.
4. Write scripts to enable ALS and findIRresonance.

Attachment 1: IMG_0659.JPG
Attachment 2: ALS_stabilized_13June2013.png
8702   Thu Jun 13 16:13:08 2013 nicolasUpdateLSCNew modeled sensing matrix

I'd repeat the measurement for REFL11. The PRC arrow has some big error bar on it, and maybe the true error is even bigger.

Also, please make the placement of the plots the same for modeled and measured so it's easy to compare.

8701   Thu Jun 13 16:01:48 2013 nicolasUpdateGreen LockingY arm locked with green but bad mode matching

 Quote: After restoring alignment I could see again strong 00 flashes (about 250-300 counts on ALS-TRY). So I locked the arm with IR and after enabling the PDH servo for the green locking, I also locked the green on the Y arm in 00 mode. Then I moved the two mode matching lenses to maximize the power into the 00 mode, but I didn't reach more than 30-35 counts. Green power injected into the Y arm                    0.680mW Green power reflected back                                  0.090mW Green power transmitted on the PSL                  few uW I would expect more power on the PSL table (maybe 10x more).

Is this reflection measured with the cavity locked or unlocked?

So what's the actual designed reflectivity of the ETM for green? No one seems to be able to give me a straight answer about this.

Looking at the reflected beam when the beam is misaligned makes it look like it's << 0.9. Is that expected given the coating spec?

You say the cavity scan goes as high as 300cts but you can only lock to 30cts, are you locked on the sideband?

8700   Thu Jun 13 15:04:16 2013 JenneUpdateLSCNew modeled sensing matrix

Using all of the latest parameters that I can find, I have re-modeled the 40m sensing matrix.  Also, I have it output the data in a format that can be used by the same plotting function as the measured sensing matrix, so they are nice and easy to compare.

The newly modeled 40m sensing matrix:

To compare, here is the measured sensing matrix from elog 8644:

Notice that (a) the units are different, so don't focus too much on the amplitudes of the lines, and (b) all of the measured and modeled matrix elements are pretty similar, except for the REFL11.  REFL11 (top right in model plot, top center in measured plot) looks like it's flipped, as well as rotated.  The new model doesn't match up too well with the Kiwamu/Koji models (which matched eachother okay), but I like that the new model matches the measurements fairly well.  The Koji sensing matrix: on the 40m wiki

EDIT: I have replaced the modelled plot with a new version.  The data and numbers are the same, but I have switched the labels on the individual radar plots, and forced them to be in the same order as they are in the measured plot.

8699   Thu Jun 13 10:57:36 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching
> > Hmmm.  You seem to be saying that more light is reflected than is injected. Is this a units problem? Or was some IR on the power meter during the 'reflected' measurement?
> > We should look at it with fresh eyes in the morning.
>
> Also, if you have been measuring the power of green refl at the rejection port of the green faraday, the polarization of the light entering the green faraday should be checked once again to make sure that you are measuring
> only the reflected power from the arm cavity.

Sorry Sorrry Sorry!!
It was 0.090 mW, I just forgot a zero!!!
Sorry!
8698   Thu Jun 13 00:35:23 2013 ManasaUpdateGreen LockingY arm locked with green but bad mode matching
> Hmmm.  You seem to be saying that more light is reflected than is injected. Is this a units problem? Or was some IR on the power meter during the 'reflected' measurement?
> We should look at it with fresh eyes in the morning.

Also, if you have been measuring the power of green refl at the rejection port of the green faraday, the polarization of the light entering the green faraday should be checked once again to make sure that you are measuring
only the reflected power from the arm cavity.
8697   Wed Jun 12 23:06:33 2013 JenneUpdateGreen LockingY arm locked with green but bad mode matching
Hmmm.  You seem to be saying that more light is reflected than is injected. Is this a units problem? Or was some IR on the power meter during the 'reflected' measurement?
We should look at it with fresh eyes in the morning. 
8696   Wed Jun 12 22:48:10 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching

After restoring alignment I could see again strong 00 flashes (about 250-300 counts on ALS-TRY). So I locked the arm with IR and after enabling the PDH servo for the green locking, I also locked the green on the Y arm in 00 mode. Then I moved the two mode matching lenses to maximize the power into the 00 mode, but I didn't reach more than 30-35 counts.

Green power injected into the Y arm                    0.680mW

Green power reflected back                                  0.090mW

Green power transmitted on the PSL                  few uW

I would expect more power on the PSL table (maybe 10x more).

8695   Wed Jun 12 01:56:58 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching

For the mode matching calculation I was using the ETMY focal length that I found on Kiwamu's plot on the wiki page.

Taking into account also the substrate, the focal length turns out to be

fl = ((n-1)*(1/R1 - 1/R2 + (n-1)d/(nR1R2)))^(-1) = -125.81 m

with n = 1.46071 (refraction index of fused silica at 532nm)

R1 = 5625 m (radius of curvature of the first surface)

R2 = 57.37 m (radius of curvature of the second surface)

d = 25mm (thickness)

The value of the focal length is sligthly different from the one I was using before in the calculation, but maybe it is enough to change the coupling.

The mode matching solution I found is very sensitive to the lenses position.

The beam waist position can vary up to 20m varying by 1cm the first lens position, while it is slightly less sensitive to the second lens displacement.

As shown in the picture, along the green beam path there is also a 1m focal length lens. It's position is fixed, because it is along the IR transmetted beam path also. I tried to get a better solution without it, but I found that the waist position was still strongly dependent on one of the two lenses position, so it would not solve the problem to remove this lens.

I think that the main issue of this mode matching is related to the "space contraints", because the two lenses' positions can vary in a very small space, even though the green beam path on the table is quite long.

Eventually, I put the MM lenses found from this last simulation on the table, and it seems to work, since I've seen very strong 00 flashes. Unfortunately, while trying to maximize the alignment I broke it  and I have to do it again, but I feel confident!

Attachment 1: waistVaryingLensPos.pdf
Attachment 2: green.JPG
Attachment 3: ModeMatchingY.pdf
8694   Tue Jun 11 22:16:56 2013 ManasaSummaryGreen LockingALS for X arm

I discussed with Yuta about the ALS servo and phase tracker and found that there was a lot of information lying around from last year but there aren't any clear elogs on how to enable ALS and obtain IR resonance.

Guide to enabling the ALS servo and find IR resonance:

The steps will explain in detail how to ressurrect the ALS servo for green X-arm and find IR resonance using ALS. The medm screens are very confusing right now.

(i) Finding the beat note

1. Get the IR to flash in TEM00 for the arm and lock it by enabling LSC (Locking the arm to IR keeps the arm cavity mirrors stable so that you can scan the temperature of the X-end laser to find the beat note).

2. Steer the X-green into the arm cavity such that the arm cavity locks in TEM00 for green as well. At this point you should also have the X-green reaching the PSL table.

3. Align the PSL doubled green (PSL-green) and the X-green in near-field (at the camera) and far-field (letting the beams to propagate beyond the Green-TRX PD).

4. Check cabling of the RF beat PD.

5. Change the X-laser temperature by sweeping the offset (C1: ALS-SLOW_SERVO2_OFFSET) in steps of 10.

6. Find the beat note and tune the alignment at the beat PD to maximize the beatnote amplitude. Disable LSC for X arm.

(ii) The GREEN HORNET explained

'Input signal conditioning' block takes I and Q signals after the delay frequency discriminator (DFD) in the beat box and these signals pass through C1ALS_BEATX_FINE filter banks. The output signal then enters the phase rotation matrix of the phase tracker. The phase tracker gives 'PHASE_OUT' which is the error signal that is fed to the ETM servo filter module (DOF filters)  through the 'Input matrix' in the medm.

An offset can also be fed to the phase tracker which will scan the beat frequency (used to find IR resonance).

(iii) Scripts

1. easyALS.py - This runs from 'ON plus' or 'ON minus' buttons in the C1ALS_COMPACT.

The script clears history of 'fine_phase' filter module and increases gain of the servo in steps ('ON plus' for positive gain and 'ON minus' for negative gain).

2. findIRresonance.py - This runs from 'IRres' button in the C1ALS_COMPACT.

It adds offset to the phase tracker in steps which scans the beat frequency to find IR resonance.

P.S. Check the scripts before enabling the servo so that the right filter modules are being turned ON. Using the wrong set of filter modules can kick the ETM.

____________________________________________________________________________________________________________________________________________________

X arm ALS progress:

I found the beat note and got ALS to work reasonably for the Xarm without kicking the ETM. I did this by manually toggling buttons and changing gains. The scripts need editing.

To do:

Modify the scripts to work as we want them to.

The ALS medm is SSSOOOO confusing. It definitely needs to be fixed (remove all unwanted parts of the screen that existed 'pre-phase tracker').

Find IR resonance.

8693   Tue Jun 11 10:00:54 2013 nicolasUpdateGreen LockingY arm locked with green but bad mode matching

 Quote: Still no good locking! After making the reflected beam size closer to the injected one, I maximized alignment. I locked again in 00 mode, but I couldn't maximize the power.  I just realized that maybe I'm not using the correct radius of curvature for the ETMY in the simulation. Tomorrow I will start checking from that.

Also make sure you are taking into account the substrate of the ETM.

8692   Mon Jun 10 21:39:26 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching

Still no good locking!

After making the reflected beam size closer to the injected one, I maximized alignment. I locked again in 00 mode, but I couldn't maximize the power.

I just realized that maybe I'm not using the correct radius of curvature for the ETMY in the simulation. Tomorrow I will start checking from that.

8691   Sat Jun 8 00:24:11 2013 AnnalisaUpdateGreen LockingY arm locked with green but bad mode matching

[Annalisa, Nic]

After connecting the PD with the reflection from the arm  to the PDH box, theY  arm has been locked on the 01 mode.  Maximizing the alignment, we obtained a 00 mode locking, but we couldn't maximize the power.

The size of the reflected beam was different with respect to the size of the incoming beam, so probably a bad mode matching was one of the issues.

Moreover, the reflected beam is very low power. We need to figure out why it is so (bad alignment? related to mode matching?)

After measuring better all the distances, I did a new mode matching calculation. I put the lenses after measuring the beam waist, so the size of the beam on the lenses was the same as expected from the calculation. Nevertheless, the beam size on the beam splitter looks bigger than expected, and also in this case green flashes into the cavity at some HOM (again 01).

I also tried to lock again the cavity and maximize the alignment, but I didn't get any improvement with respect to the previous mode matching.

8690   Fri Jun 7 23:44:54 2013 KojiUpdateGeneralProjector - lightbulb replaced

http://nodus.ligo.caltech.edu:8080/40m/7885

8689   Fri Jun 7 21:33:39 2013 ManasaUpdatePSLPSL green to Y- BEAT PD blocked

To allow Annalisa to work on the Y-green alignment as I work with the X-green, the part of the PSL green beam that goes to the Y-green beat PD has been blocked with an iris.

ELOG V3.1.3-