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ID Date Author Type Category Subject
982   Mon Sep 22 22:24:19 2008 ranaConfigurationPSLbad FSS

 Quote: The MC refl power was going up and the FSS PC drive was so large that I had to turn up the FSS...

Looks like I bumped the PS for the 21.5 MHz test setup and changed the supply voltage of the amplifier
from +24 to +38 V. This made the amplifier go hot after a few hours and the output eventually dropped.

Yoichi and I walked out there now and it was too hot to touch. We turned it off and put it on a heat
sink to make it chill out and it came back after a few minutes. We have set the input to the amp to
be -7 dBm instead of -8 dBm after deciding that we should take into account the 1 dB loss in the cable
run and deliver a real +17 dBm to the mixer.

The right way is to calibrated the LO mon of the FSS.
11329   Thu May 28 10:42:19 2015 SteveUpdatePEMbad Guralp X-cable
 Quote: Tried swapping cables at the Guralp interface box side. It seems that all of our seismic signal problems have to do with the GUR2 cable being flaky (not surprising since it looks like it was patched with Orange Electrical tape!! rather than proper mechanical strain relief). After swapping the cables today, the GUR2 DAQ channels all look fine: i.e. GUR1 (the one at the Y end) is fine, as is its cable and the GUR2 analog channels inside the interface box. OTOH, the GUR1 DAQ channels (which have GUR2 (EX) connected into it) are too small by a factor of ~1000. Seems like that end of the cable will need to be remade. Luckily Jenne is still around this week and can point us to the pinout / instructions. Looks like there could be some shorting inside the backshell, so I've left it disconnected rather than risk damaging the seismometer. We should get a GUR1 style backshell to remake this cable. It might also be possible that the end at the seismometer is bad - Steve was supposed to swap the screws on the granite-aluminum plate on Thursday; I'll double check.

The Guralps were swapped.

What I did:   turned DC power off at 1X1,  hand carried them,  centered  each leveling bubbles, gently locked the jack screws and turned power back on.

ETMY at the east end now has CMG-T40-0008, sn T4157 as channel C1:PEM-SEIS_STS_1_Y_OUT_DQ.........

ETMX at south end now has CMG-T40-0053, sn T4Q17 as channel C1:PEM-SEIS_STS_2_Y_OUT_DQ.........

Conclusion:  Guralps are fine.  X  cable is bad. It was bad 6 months ago when it was made.

We can still swap the 3ft short cables at the granite base if Rana has not done it.

Attachment 2: swappedGurs.png
4937   Tue Jul 5 08:32:38 2011 steveUpdatePEMbad air quality in the lab

The fireworks of yesterday showing up in the lab. Pasadena out side air 6.6 million  cfm for 0.3 micron particles  and 1.5 million cfm for 0.5 micron size.

Attachment 2: july4pem.jpg
3742   Tue Oct 19 21:10:27 2010 yutaUpdateCDSbad filter coefficients for every suspensions!

(Koji, Yuta)

Summary:
The damping servos of the MC suspensions has not been working since yesterday. They had worked on Friday.
We found that some of the filter coefficients somehow changed from the correct value during dealing with the sampling frequency shift (from 2048Hz to 16384Hz). (see elog #3659)

What we did:
We thought that the problem occurred from the CDS update on Monday. So, we restored them using svn.
1. Went to /opt/rtcds/caltech/c1/core/advLigoRTS and ran svn update using the revision number 2125.
svn update -r 2125
2. Rebuilt all the front ends.
ssh -X c1sus
cd /opt/rtcds/caltech/c1/core/advLigoRTS
make clean-SYSNAME
make SYSNAME
make install-SYSNAME
(where SYSNAME=c1x02,c1sus,c1mcs,c1rms)
3. Restarted the front end models.
ssh -X c1sus
cd /opt/rtcds/caltech/c1/scripts
sudo startc1SYS
(where SYS=sus,mcs,rms)
4. Restarted mx_streams.
sudo /etc/restart_streams
See this wiki page for the restart procedures.

At this point we judged that the realtime system and "dataviewer" worked fine (by poking some suspensions / by measuring PSDs/TFs of the signals).

However, just restoring the RT system didn't fix the damping servos.

After that, we measured the transfer functions of the servo filters using DTT(diaggui on rosalba).
5. The filter at MC1_SUSPOS, "3:0.0" should have a cut-off frequency at 3Hz, but it was around 0.3Hz.
6. We used foton in order to look at the filter bank files (in /cvs/cds/rtcds/caltech/c1/chans). Then we found that the filter design was somehow changed to
zpk([0],[0.375],2.66666,"n")
zpk([0],[3],0.333333,"n")

Why the filter designs changed?:
We suspect that the filter designs were changed because of the replacement of sampling frequency in filter bank files(see elog #3659). We only replaced the lines like
# SAMPLING SUS_MC3_SUSPOS 2048
to
# SAMPLING SUS_MC3_SUSPOS 16384
and didn't changed the coefficients.
This may caused a problem when opening the files with foton, and foton changed 3Hz to 0.375Hz (2048/16384) and other coefficients.

Note:
The damping servo for SIDE has been working for every MCs. POS, PIT, YAW are the ones not working.

Next work:
- Fix filters for every suspensions.
There are backup files in /cvs/cds/rtcds/caltech/c1/chans/filter_archive directory, so this should help.
But I don't think just fixing filters would fix the damping servo because the filter design of MC suspensions were changed this morning and the damping had worked until Friday.

3173   Wed Jul 7 22:52:38 2010 rana, nancyConfigurationIOObad length control offset for the MC

Rana found out that a connection was bad in the shown place, due to which the MEDM screen was showing bad offset for length control.

Basically, the offset slider value would not go into the system because of that bad connection, and was locking the mode cleaner at the wrong location.

Attachment 1: P7070251.jpg
Attachment 2: Screenshot.png

It turned out the oplev controls on ETMY were just bad.

It looks like the whitening filters have been OFF and because of that the resultant open-loop was not crossing the unity gain.

I will check the whitening filters.

(open-loop transfer function)

The blue dots are the measured data points and the green curve is the fit.

Apparently the open-loop doesn't go above the unity gain, so the oplev had been doing nothing.

If we try to increase the overall gain it will oscillate because of the phase delay of more than 180 deg around 3 Hz.

The red curve is the expected one with the whitening filters (WFs) properly engaged.

Note that WF are supposed to have two zeros at 1 Hz and two poles at 10 Hz.

 Quote from #5518 (to do)  + optimization of the ETMY oplevs and OSEM damping.

2975   Mon May 24 14:28:35 2010 kiwamuUpdateElectronicsbad power supply of a vme rack

In this morning I found daqawg didn't work.

After looking for the cause, I found one of the vme racks mounted on 1Y6 doesn't work correctly.

It looks like the vme rack mounting c0daqawg could not supply any power to the frontends.

Now Steve and I are trying to look for a spare for it.

2978   Tue May 25 07:22:59 2010 kiwamuUpdateElectronicsbad power supply of a vme rack

Notes on May 25th

Don't do the following things !! This causes bad cross-talking of CPUs mounted on the crate.

I moved c0daqawg and c1pem1 from 1Y6 vme crate to 1Y7 crate due to the bad power supply.

Another problem: c0dcu1 doesn't come back to the network.

After moving them, I tried to get back them into the RFM network. However  c0dcu1 never came back, it still indicates red in C0DAQ_DETAIL.adl screen.

Alberto and I did even "nuclear option" (as instructed), but no luck.

2981   Tue May 25 10:06:09 2010 kiwamuUpdateElectronicsbad power supply of a vme rack

I got a VME crate from Peter's lab. It is already installed in 1Y6 instead of the old broken one.

I checked its power supply, and it looked fine. It successfully supplies +5, +12 and -12 V. And then I put c0daqawg and c1pem1 back from 1Y7.

Now I am trying to reboot all the front end computers with Peter's VME crate. A picture of the VME crate will be updated later.

7356   Fri Sep 7 00:08:10 2012 janoschMetaphysics baffle clipping loss

With a curvature radius of about 57m for the ETMs, flat ITMs at the beam waist, and using 39m for the arm lengths, one finds that the beam radius at the ETMs is about 5.3mm. The clipping power loss of a 5.3mm beam through a 20mm radius baffle hole would be less than a ppm of a ppm if the beam was perfectly centered. If the baffle hole had 15mm radius, the clipping loss would be 0.01ppm. If the baffle hole had 10mm radius, the loss would be 810ppm. The loss values are calculated using the formula of the  "Gaussian beam" Wikipedia article, "Power through an aperture" section. So I did not check if that one is ok.

7358   Fri Sep 7 09:37:20 2012 SteveUpdateCamerasbaffle plate for SOS

 Quote: The alignment of the pick-off mirror near ETMX is done. Everything turned out to be easy once we realized that there is no sense getting the alignment laser (going through viewport to pick-off to ITMX) back to ETMX. It is only necessary to hit ITMX somehow, since this makes sure that there is one scattered beam that will make it from ITMX to pick-off through viewport. After the auxiliary optic (that we never used in the end) was removed again, we levelled the optical table. So in the current setup, we can have small-angle scattering measurements on ITMX and large-angle scattering measurements on ETMX.

This is how it was envisioned. The video camera was in nobodies mind to look through the 40 mm  diameter hole than.

Attachment 1: IMG_1624.JPG
Attachment 2: IMG_1618.JPG
Attachment 3: IMG_1616.JPG
7375   Wed Sep 12 17:02:00 2012 SteveUpdateCamerasbaffle plate hole getting larger

Quote:

 Quote: The alignment of the pick-off mirror near ETMX is done. Everything turned out to be easy once we realized that there is no sense getting the alignment laser (going through viewport to pick-off to ITMX) back to ETMX. It is only necessary to hit ITMX somehow, since this makes sure that there is one scattered beam that will make it from ITMX to pick-off through viewport. After the auxiliary optic (that we never used in the end) was removed again, we levelled the optical table. So in the current setup, we can have small-angle scattering measurements on ITMX and large-angle scattering measurements on ETMX.

This is how it was envisioned. The video camera was in nobodies mind to look through the 40 mm  diameter hole than.

Rana is proposing 50 mm hole in the baffle plate that is attached to the tower.  Atm1

Atm2 is showing the back side where the solid line is 40 mm

Attachment 1: IMG_1631.JPG
Attachment 2: IMG_1628.JPG
620   Wed Jul 2 00:59:13 2008 MashaUpdateAuxiliary lockingbalanced detection, noise plots, progress
Progress report submitted today(!). It is on the 40m wiki page. Below is a figure of some estimated noise sources.

Made voltage divider that acts as an attenuator for one of the paths in the Mach Zehnder, which should help to balance the detection and reduce noise.

First tested using a 636 Hz Matlab generated audio signal (thanks to John inspiration on portable headphones). Figure is attached, with plots of noise spectra of original and optimized signal with and without added acoustic noise (visible as peaks as 636 and 1272 Hz, linewidth approx 4 Hz). My first try at optimization reduces the noise by nearly an order of magnitude for most frequencies.

Will work on finding different noise source to better see what happens at low frequency, and try to get finer control of tunable gain.
Attachment 1: noise_sources.pdf
Attachment 2: balancing_detectors.png
5062   Fri Jul 29 16:25:06 2011 kiwamuUpdateASCbeam axis and Y arm aligned

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

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

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

++ Motivation ++

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

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

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

++ what I failed ++

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

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

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

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

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

++ what I did ++

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

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

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

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

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

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

893   Thu Aug 28 18:56:14 2008 ranaConfigurationPSLbeam block distorted
There was a beam block after the Mach Zender. Who or what put this there?

The going to the MC now looks distorted as if someone has left something funny in the beam or maybe the new PMC has started to degrade??

Use the ELOG people...its good for you.
896   Fri Aug 29 10:20:32 2008 YoichiConfigurationPSLbeam block distorted

 Quote: There was a beam block after the Mach Zender. Who or what put this there? The going to the MC now looks distorted as if someone has left something funny in the beam or maybe the new PMC has started to degrade?? Use the ELOG people...its good for you.

I put the block. I was frequently reaching to the FSS box to change the test point probes. I put the block to protect my hands/clothes from being burnt accidentally.
902   Fri Aug 29 16:35:18 2008 YoichiConfigurationPSLbeam block distorted

 Quote: There was a beam block after the Mach Zender. Who or what put this there? The going to the MC now looks distorted as if someone has left something funny in the beam or maybe the new PMC has started to degrade?? Use the ELOG people...its good for you.

The apparent distortion of the MC refl. was caused by mis-alignment of the MC mirrors.
Because the MC1 was mis-aligned, the reflected light was clipped by a steering mirror.
I restored the MC angle bias values from the conlog history and now the MC locks.
According to conlog, the MC alignment was changed at around 18:30 on Thursday PDT.
It could have been caused by the computer reboots.
9420   Thu Nov 21 10:24:50 2013 KojiUpdateSUSbeam dumps

You don't need the fourth glass piece on the diamond beam dump.

9448   Fri Dec 6 15:57:41 2013 SteveUpdateIOObeam dumps for PSL pointing monitoring

 Quote: Since the pointing has gone bad again, I went to the PSL to investigate. Found some bad things and removed them: 1) There was a stopped down iris AGAIN in the main beam path, after the newly installed mirror mount. I opened it. Stop closing irises in the beam path. 2) The beam dump for the IOO QPD reflection was just some black aluminum. That is not a real dump. I removed it. We need two razor blade dumps for this. 3) There was an ND filter wheel (???) after one of the PMC steering mirrors. This is not good noise / optics practice. I removed it and dumped the beam in a real dump. No elog about this ?!#?   The attached trend shows the last 20 days. The big step ~2 weeks ago is when Steve replaced the steering mirror mount with the steel one. I don't understand the drift that comes after that.   Today I also spent ~1 hour repairing the Aldabella laptop. Whoever moved it from the PSL area to the SP table seems to have corrupted the disk by improper shutdown. Please stop shutting the lid and disconnecting it from the AC power unless you want to be fixing it. Its now running in some recovery mode. Lets leave it where it is next to the PSL and MC1. I steered the MC suspensions back to where they were on the trends before the PSL mirror mount swap and then aligned the PSL beam into it by touching the last 2 steel mounts. Once the alignment was good without WFS, I centered the beams on the IOO QPDs. If it behaves good overnight, I will center the unlocked beams on the MC WFS.   Please stay off the PSL for a couple days if you can so that we can watch the drift. This means no opening the doors, turning on the lights, or heavy work around there.

IOO pointing monitoring qpds received razor beam dumps on their refs.

The Pos QPD was rotated and recentered.

The Ang QPD was left untouched.

TREND plot of 23 days is attached.

Attachment 1: IOO_QPD_MONS.jpg
Attachment 2: PointingTrend23d.png

Anodized aluminum dumps replaced by 6 razor beam dumps.

Two more razor beam dumps added this afternoon.   The picture will updated tomorrow.

Attachment 1: razorbeamdumps.jpg
Attachment 2: razorbeamdumpss.jpg
9325   Fri Nov 1 09:45:32 2013 SteveUpdateIOObeam dumps to be find

Quote:

 Quote: Steve, can you please put 2 mounted  razor dumps near the WFS for this purpose??                 Tuesday: Razor dumps are waiting for you.

I couldn't find any dumps near the WFS. Koji looked. I looked twice. Maybe they are spooky and absorbing all of the light?

The MC alignment was bad and the WFS were making it drift. Koji aligned the beam into the PMC. I then restored the MC suspensions to where they were 8 days ago (back when the transmission and reflection were good). With the WFS OFF, this gave us a MC trans ~ 16000. With WFS ON it goes to 17500 which is about as good as its been over the last 80 days.

I centered the beam on the WFS with the MC unlocked and also centered the beam on the whole WFS path (it was near clipping between WFS 1 & 2). Also for some reason that beamsplitter which steers the beam onto WFS1 is a R=33% (!? why is this not a R=50% ??).

Steve, please swap this out to a BS1-1064-50-1025-45S if we have one sitting around. If not, we want to add this to the CVI purchase list, but not buy until we get a bigger list together.

I also centered this newly aligned beam into the IMC onto the PSL QPDs. We should now use these as a pointing reference for the beam into the IMC.

While doing this I noticed that the beam was almost clipping on the Uniblitz shutter used to block the PSL beam. That shutter is mounted too short and was also not centered horizontally. I removed it for now so that Steve can find a more adjustable mount for it and put it back into play. The beam going into the IMC is BIG, so you have to very careful when centering the shutter. Might be that we cannot leave it at 45 deg and still get a big enough aperture.

Note #3 for Steve: please also replace the mount for last steering mirror into the IMC with a Polanski or a Superman, that black Ultima is no good. Also the dogs must be steel - no aluminum dogs for our sensitive places.

No wonder they could not find the beam dumps. Last night was Haloween. They should of just said: Trick or treat! where are the beam dumps?

Attachment 1: razor_beam_dumps.jpg
7801   Sun Dec 9 01:21:51 2012 DenUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

 Quote: Today I wanted to check that AS and REFL beams are real and contain proper information about interferometer. For this I locked YARM using AS55_I and REFL11_I. Then I compared spectrum with POY11_I locking. Everything is the same. I've also adjusted phase rotations of AS55 (0.2 ->24) and REFL11 (-34.150 -> -43).

I studied more carefully beam path inside DRMI using PRM face camera and found that beam is clipping on PR3 edge.

Step 1: PRCL LOCK, MICH LOCK, power build up 30.

Note: left is right and vice versa on the PRM camera

Step 2: PRLC - UNLOCK, MICH - LOCK, PRM is still aligned. Right photo is AS port. I've slightly misaligned ITMs such that disturbance of AS beam is clearly seen.

Step 3: PRCL - UNLOCK, MICH - LOCK, PRM misalined in yaw such such that the beam LASER -> PRM -> PR2 -> PR3 -> BS -> ITMX -> BS -> PR3 -> PR2 -> PRM -> PR2 -> PR3 is completely clipped on the TT edge. AS beam is now not clipped.

So the conclusion is that when PRC is not locked and beam is thin, it can avoid clipping. When PRC locked, beam size grows and it starts to clip. I think we need to move the mount next to PR3 because of it we to not have enough space to align the TT.

Step 4: PSL shutter is closed.

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.

7803   Mon Dec 10 03:02:03 2012 DenUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

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

I think about power buildup as a ratio of the power in the cavity when it is locked and unlocked = (POYDC_LOCKED - POYDC_OFFSET) / (POYDC_UNLOCKED - POYDC_OFFSET). I do not multiply this number by PRM transmission.

POYDC_OFFSET = -0.006

POYDC_UNLOCK = 0.063

For example, on the plot below power buildup is 15.

7804   Mon Dec 10 10:13:41 2012 DenUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

That's OK, but its best to use standard notation. The power recycling gain is defined as the power incident on the BS divided by the power incident on the PRM from the laser side. You should also compare it with the PRC gain that you expect from mirror transmissions.

7806   Mon Dec 10 22:34:34 2012 DenUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

 Quote: That's OK, but its best to use standard notation. The power recycling gain is defined as the power incident on the BS divided by the power incident on the PRM from the laser side. You should also compare it with the PRC gain that you expect from mirror transmissions.

I've made snapshots of PR2, PRM, ITMY and ITMX mirrors. Power buildup recycling gain (POWER BS / POWER PRM) was equal to 3-4.

7820   Thu Dec 13 03:20:48 2012 DenUpdateLSCbeam inside DRMI is clipping on PR3 Tip-Tilt

 Quote: I've made snapshots of PR2, PRM, ITMY and ITMX mirrors. Power buildup recycling gain (POWER BS / POWER PRM) was equal to 3-4.

We've looked at PR2 face camera when PRM, BS and one of the ITMs were aligned. We saw an extra beam at PR2 when ITMX was aligned (right plot). This spot stays on the PR2 when prcl is locked.

Then we looked at PR3 transmission mirror and saw that the main beam is not on the edge of the mirror. Secondary beam is clipping on the mirror mount of PR3 that we see on BS_PRM camera.

Measured beam spot positions:

 Optics Pitch, mm Yaw, mm ITMX 5.6 1.5 ETMX -1.5 1.5 ITMY 4.8 -1.5 ETMY -1.4 5.6 PRM 2.7 4.1

"+" for pitch means that the beam is too high, "-" too low

"+" for yaw means that the beam is left if you look from the back, "-" is right

Beam spots were measured using x, y arm and prcl locking to the carrier.

4039   Thu Dec 9 23:17:47 2010 kiwamuUpdateSUSbeam pointing has been done

[Koji, Osamu and Kiwamu]

We aligned the beam axis pointing down to both X and Y arm.

Now the beams are hitting the centers of both ETMX and ETMY.

Amazingly Osamu made X arm flashing by aligning the cavity.

(what we did)

- opened almost all the chambers except for the MC2 chamber.

- locked and aligned the MC.

We set Marconi to the right frequency, which had been set to the default values, probably due to the power outage in the last weekend.

Also we found a DAC cable disconnected from the IO chassis of c1sus. So we connected it in order to damp the MC suspensions.

- aligned MMT2 and PZT2 in order to let the beam go through the center of PRM.

- checked the beam centering at the two TTs (PR2, PR3).

- rotated PR3 to make the beam go through the centers of both ITMY and BS at the same time.

- tried finding the beam spot at the ETMY chamber, and successfully found it.

To see such faint beam spot, we used an IR viewer.

In addition to that, we put a large piece of aluminum foil as a screen in the chamber.

- aligned the beam to the center of ETMY by tweaking the PZT mirror (SM2).

- aligned the BS so that the reflected beam at the BS goes through the center of ITMX.

- tried finding the beam spot at the X end, and successfully found it hitting the wall in the chamber.

- aligned the BS in order to let the beam hit the center of ETMX.

- tried aligning ETMX and ITMX to the beam.

Eventually we made the X arm flashing.

However the flash was a bit too weak to completely align the cavity.

(plan for tomorrow)

- reinstall some steering mirrors into the BS chamber

- check and neutralize PZT1

- alignment of IP_ANG

4040   Fri Dec 10 09:58:57 2010 AidanUpdateSUSbeam pointing has been done

Good news. I feel multi-chromatic-locking success is just around the corner.

By the way, there's a new presentation on the DCC from the ANU group where they've locked a short single cavity with both colors - G1000735:

https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=14040

 Quote: [Koji, Osamu and Kiwamu]  We aligned the beam axis pointing down to both X and Y arm. Now the beams are hitting the centers of both ETMX and ETMY. Amazingly Osamu made X arm flashing by aligning the cavity.

4874   Fri Jun 24 00:13:24 2011 kiwamuUpdateABSLbeam profile measurement of LWE

The beam profile of the LWE (LightWave Electronics) NPRO was measured.

Mode matching telescopes will be designed and setup soon based on the result of the measurements.

Here is a plot of the measured beam profile.

(some notes)

The measurement was done by using Kevin's power attenuation technique (#3030).

An window was put just after the NPRO and the reflected beam was sampled for the measurement to avoid the beam scan saturated.

3570   Mon Sep 13 22:51:07 2010 tara,valeraConfigurationPSLbeam scan for RCAV

On Friday, Valera and I calculated the modematching for reference cavity from AOM.

We scan the beam profile where the spot should be.

The first beam waist in the AOM is 103 um, the lens (f= 183 mm, I'm not sure if I have the focal length right) is 280 mm away.

The data is attached. The first column is marking on the rail in inches,

the second column is distance from the lens, the third and fourth column are

vertical and horizontal spot radius in micron. Note that the beam is very elliptic because of the AOM.

Attachment 1: 2010_09_10_w.mat
7527   Thu Oct 11 11:20:05 2012 janoschUpdateGeneralbeam shape simulation, PRC

I started to create a Finesse model of the PRC cavity. We have the phase maps for the PRC and the two ITMs. I could not find anything for PR2,3 and BS. All files can be found in my SVN folder /janosch/PRC40m. I used the AutoCAD model to determine angles of incidence and distances. These numbers are largely inconsistent with numbers that you can find elsewhere on the 40m wiki, but this certainly depends on what accuracy is required for interferometer alignment and I don't understand anything about alignment.

The phase maps come in a format that needs to be modified before they can be used in Finesse. I have started with this work, but maybe someone else can take over. The phase maps show tilts and the PRC also has the curvature. These have to be subtracted out before the maps can be loaded into Finesse. I asked GariLynn for the code that they use. The Finesse model (MichPRC_40m.kat) does not load the phasemaps yet, and I just wrote some random parameter values for the TEM00 input beam to the PRC. So these Gauss parameters need to be corrected.

I will only go on with this work if Rana tells me that I should do so, otherwise it is on hold until we have a volunteer.

4110   Wed Jan 5 03:06:02 2011 kiwamuUpdateIOObeam spots on MC mirrors

I checked the spot positions on MC1 and MC3 by running Yuta's A2L script.

The amounts of the off-centering were good except for YAW of MC1.

So we have to adjust the YAW alignment of the beam axis by steering the mirrors at the PSL table.

- - - (measured off-centering) - - -

MC1_PIT  =  -0.711 mm

MC1_YAW =  1.62 mm

MC3_PIT  =   -0.0797 mm

MC3_YAW  =  - 0.223 mm

 Quote: We will check the spot positions more accurately by A2L technique.

528   Tue Jun 10 08:37:18 2008 steveUpdatePSLbeam trap is being tested
High power beam trap is being tested just west of FSS area on psl enclosure.

When the pmc is operating at low power that means that the rest of the 3W is going into the
circular SS trap.

Please beware of the high power beam trap test
Attachment 1: trapss3w.png
6648   Thu May 17 15:31:22 2012 steveUpdateGeneralbeam trap posts & clamps for vacuum

Aluminum posts and SS clamps for green glass traps in vacuum will be out of the shops by June 6, 2012 the latest

Attachment 1: 05161201.PDF
Attachment 2: 05151201.PDF
5047   Wed Jul 27 15:38:01 2011 steveUpdateVACbeam traps for vacuum

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

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

Attachment 1: P1080095.JPG
8087   Fri Feb 15 09:58:49 2013 SteveUpdateGeneralbeam traps ready to be installed

Black-green glass traps are ready for light in vacuum. I can assemble more if needed. These three sizes are available.

Attachment 1: IMG_0083.JPG
Attachment 2: IMG_0084.JPG
8089   Fri Feb 15 16:09:19 2013 KojiUpdateGeneralbeam traps ready to be installed

For the hexagonal one, insert one of the glass plate only half. Use a 1"x.5" piece if exists.

For the diamond one, you don't need the forth glass piece.

Attachment 1: HexBeamDump.pdf
Attachment 2: DiamondBeamDump2in.pdf
5872   Fri Nov 11 12:32:45 2011 KatrinUpdateGreen Lockingbeat PSL - YARM laser

[Suresh, Katrin]

Measured frequency fluctuation of the beat between PSL and YARM lasers.

Yesterday, it was very tricky to adjust the voltage offset to the slow YARM laser input to achieve the appropriate beat frequency. Today, it was much easier. During measurement beat around 25 MHz. Calibration factor 40 mV per 10 MHz.

4211   Thu Jan 27 11:04:27 2011 KojiUpdateGreen Lockingbeat freq scan

Experiment in the night of Jan 26.

o The arm was locked for the IR beam and was aligned for it.
o The green was aligned to the arm
o The beat freq was observed with the RF analyzer and the webcam.
o Engaged the ALS servo
o Compared the fluctuation of the beat freq with and without ALS
o Scanned the beat freq in order to find an IR resonance

The beat freq was scanned. A resonance for IR was found.
However, the residual motion of the arm was not within the line width of the IR resonance.

To Do
- Improve the ALS servo (==>Koji)
- VCO noise characterization (==>Suresh is on it)
- Calibrate the PLL feedback (i.e. ALS error) into Hz/rtHz (==>Suresh)
- Calibrate the end green PZT fb into Hz/rtHz (==>Osamu is on it)
- Tuning of the suspension filters to reduce the bounce mode coupling.

DETAILS

o How to lock the arm with IR

• Coarsely align the arm without lock. Transmittion was ~300 with MCTRANS ~40000
• REFL11I is the error signal. unWhiten filter (FM1) should be on.
• Unlock the MC and null the error and the arm trans offset by running the following commands

ezcaservo -g -0.1 -r C1:LSC-REFL11_I_OUTPUT C1:LSC-REFL11_I_OFFSET ezcaservo -g -0.1 -r C1:LSC-REFL11_Q_OUTPUT C1:LSC-REFL11_Q_OFFSET ezcaservo -g 0.1 -r C1:LSC-TRX_OUTPUT C1:LSC-TRX_OFFSET

• Confirm the input matrix to pass REFL11I to MC path (why don't we use XARM path...?)

ezcawrite C1:LSC-MTRX_81 1.0

• Servo configuration
• For acquisition: Gain of 2. Only FM1 (1000:10) has to be on.
• After the acquisition (TRX>200): The gain is to be changed to 1. FM2 and FM3 can be turned on for the LF boost.
• Actuator matrix: connect MC path to ETMX and MC2

ezcawrite C1:LSC-OM_MTRX_18 1.0 ezcawrite C1:LSC-OM_MTRX_78 1.0

o How to align the green beam

• After the alignment I went the end and aligned the last two steering mirrors.

o The beat freq monitor

• Put the RF analyzer at the RF splitter of the RFPD output.
• Used Zonet webcam (http://192.168.113.201:3037) for the remote monitoring

o How to engage the ALS servo

• Preparation:
• VCO PLL feedback comes to X_FINE path.
• Put an offset of -850 to cancel too big offset (when the VCO is unlocked)
• Use Y_FINE channel for the offset addtion. FM1 is 10mHz LPF in order to make the offset smooth.
• Add X_FINE and Y_FINE by the matrix.
• Control
• Turn off X_FINE out. Leave Y_FINE output turned on.
• Turn on ETMX ALS path.
• Servo setting: FM1 1000:30 ON, others OFF, gain1
• Wait for the beat comes in to the locking range at around 80MHz.
• If the peak is too far, sweep Y_FINE offset in order to . Or change GCV slow thermal offset to let the beat freq jump.
• You may have ambiguity of the feedback sign depending on which green has higher freq.
• After the capture of the ALS lock, increse the gain up to 20. Turn on 0.1:boost at FM3.

o Comparison of the stability of the beat freq (Attachment3)

• The spectra of the VCO PLL feedback was measured.
• First of all, the signal was measured without ALS (blue).
The PLL lost lock quite frequently, so the careful adjustment of the offset was necessary.Still I think there was slight saturation upconversion.
• Then, the ALS was turned on (red). The gain was 20. This is an in-loop evaluation of the servo. The suppression was ~1000 at 1Hz.

o Beat freq scanning

• The following command was used for the beat note scanning

ezcastep -- "C1:GCV-YARM_FINE_OFFSET" "5,500"

• Once the IR transmission was found, the scan was stopped.
• Because the resultant rms stability of the arm was not within the line width of the cavity, the smooth resonant curve was not obtained.
• From the shape of the error signal the peak-to-peak displacement (f>1Hz) was estimated to be +/-0.7nm. The dominant displacement
in the period is 16Hz component.

Attachment 1: arm_scan.pdf
Attachment 2: arm_cav_scan3.png
Attachment 3: 110126_ALS_inloop.pdf
4268   Thu Feb 10 05:06:35 2011 kiwamuUpdateGreen Lockingbeat noise : a little bit better, and 1Hz peak from amplitude noise coupling

I repeated the same measurement as that Koji did before (see here) with the mixer-based frequency discriminator.

The frequency fluctuation of the beat note is now 50 kHz in rms integrated down to 0.1 Hz, which is a bit better than before.

However there still is the same undesired structure in the spectrum below 10 Hz.

Fig.1 power spectra of the green beat note fluctuation in terms of frequency fluctuation.

Red curves were taken when the IR was locked to the MC, and the green was locked to the X arm.

Blue curves were taken when both the IR and the green were locked to the X arm.

Black curve was also the one taken when the IR and the green were locked to the X arm, but showing the lower noise level.

I have no idea what exactly was going on when I took the black curve, but this noise level sometimes showed up.

The discrepancy may come from a kind of calibration error although I kept using the same calibration factor to convert the data from count to frequency.

Need more investigations.

Additionally Koji and I took the coherence between the beat fluctuation and the transmitted lights of both the IR and the green.

It showed a strong coherence at 1 Hz, which is one of the dominant noise of the beat note.

This probably indicates that the 1 Hz peak is produced by a coupling from amplitude fluctuation.

For monitoring the green transmitted light, I used the Jenne's PD (see here)

6302   Tue Feb 21 22:06:18 2012 jamieUpdateLSCbeatbox DFD installed in 1X2 rack

I have installed a proto version of the ALS beatbox delay-line frequency discriminator (DFD, formally known as MFD), in the 1X2 rack in the empty space above the RF generation box.

That empty space above the RF generation box had been intentionally left empty to provide needed ventilation airflow for the RF box, since it tends to get pretty hot.  I left 1U of space between the RF box and the beatbox, and so far the situation seems ok, ie. the RF box is not cooking the beatbox.  This is only a temporary arrangement, though, and we should be able to clean up the rack considerably once the beatbox is fully working.

For power I connected the beatbox to the two unused +/- 18 V Sorensen supplies in the OMC power rack next to the SP table.  I disconnected the OMC cable that was connected to those supplies originally.  Again, this is probably just temporary.

Right now the beatbox isn't fully functioning, but it should be enough to use for lock acquisition studies.  The beatbox is intended to have two multi-channel DFDs, one for each arm, each with coarse and fine outputs.  What's installed only has one DFD, but with both coarse and fine outputs.  It is also intended to have differential DAQ outputs for the mixer IF outputs, which are not installed in this version.

The intended design was also supposed to use a comparator in the initial amplification stages before the delay outputs.  The comparator was removed, though, since it was too slow and was limiting the bandwidth in the coarse channel.  I'll post an updated schematic tomorrow.

I made some initial noise measurements:  with a 21 MHz input, which corrseponds to a zero crossing for a minimal delay, the I output is at ~200 nVrms/\sqrt{Hz} at 5 Hz, falling down to ~30 nVrms about 100 Hz, after which it's mostly flat.  I'll make calibrated plots for all channels tomorrow.

The actual needed delay lines are installed/hooked up either.  Either Kiwamu will hook something up tonight, or I'll do it tomorrow.

6794   Mon Jun 11 21:50:08 2012 yutaUpdateGreen Lockingbeatbox looks OK

Summary:
We need I-Q frequency deiscriminator to control the arm length fine and continuously.
I checked the beatbox (LIGO-D1102241-v4; see elog #6302) and it was working.

What I did:
1. Measured some transferfunctions with a network analyzer (Aligent 4395A) and checked the cabling is correct.

2. Put 30 m/1.5 m delay line and checked I-Q outputs are actually orthogonal. I did this by sweeping the frequency of RF input to the beatbox. See attached picture. You can see nice circle on the oscilloscope.

Some measurement results:

- Gains of the transferfunctions(@ 10-100MHz) between;

RF in -> RF mon: -25 to -20 dB
RF in -> fine delay out: -50 to -40 dB
RF in -> coarse delay out: -50 to -40 dB
RF in -> LO of mixer RMS-1: ~ +4 dB  (RMS-1 needs +7 dB LO)

- 30m delay line(RG-142B/U) had -2 dB loss.

Note:
- RF input must be larger than about -3 dBm to get enough LO to the mixer. Otherwise, you won't get I-Q outputs.
- The comparator, whitening filter and differential DAQ outputs are not installed in the current beatbox.
- Current beatbox only has electronics for the one arm.
- The print on the board D1102241 says +15V and -15V, but they are actually opposite. Cabling is swapped in order to supply correct power to the ICs.

Attachment 1: CIMG1522.JPG
734   Thu Jul 24 11:49:07 2008 MashaSummaryAuxiliary lockingbelated weekly summary
I designed a high pass filter to whiten the spectrum from the Mach Zehnder to optimize the
input into the ADC. The swept sine response measurement and the effect of the filter on the
spectrum are attached. If I start using the digital system (it is currently down in Bridge),
I will decide if the filter needs to be improved/better matched to the ADC there.

I moved from the 40m to Rana's lab in bridge. I am making a new and improved Mach Zehnder
setup with a 50m fiber in one arm; currently the transmission through the fiber is 44%. I
am working out how to mode match the laser to the fiber to improve this number.
Attachment 1: filter_tr_function.pdf
Attachment 2: filtered_spectr0724.pdf
7342   Tue Sep 4 20:25:22 2012 jamieOmnistructureVACbetter in-air "lite" access connector needed

We really need something better to replace the access connector when we're at air.  This tin foil tunnel crap is dumb.  We can't do any locking in the evening after we've put on the light doors.  We need something that we can put in place of the access connector that allows us access to the OMC and IOO tables, while still allowing IMC locking, and can be left in place at night.

7343   Wed Sep 5 09:50:25 2012 SteveOmnistructureVACbetter in-air "lite" access connector needed

 Quote: We really need something better to replace the access connector when we're at air.  This tin foil tunnel crap is dumb.  We can't do any locking in the evening after we've put on the light doors.  We need something that we can put in place of the access connector that allows us access to the OMC and IOO tables, while still allowing IMC locking, and can be left in place at night.

It is in the shop. It will be ready for the next vent. Koji's dream comes through.

Attachment 1: IMG_1612.JPG
7344   Wed Sep 5 10:50:15 2012 jamieOmnistructureVACbetter in-air "lite" access connector needed

Quote:

 Quote: We really need something better to replace the access connector when we're at air.  This tin foil tunnel crap is dumb.  We can't do any locking in the evening after we've put on the light doors.  We need something that we can put in place of the access connector that allows us access to the OMC and IOO tables, while still allowing IMC locking, and can be left in place at night.

It is in the shop. It will be ready for the next vent. Koji's dream comes through.

Can we see the full design?  If we can't lock the mode cleaner with this thing on then it's really of no use.  We want it to be equivalent to the light doors, but allow us to keep the mode cleaner locked.  That's the most important aspect.

7345   Wed Sep 5 13:11:43 2012 jamieOmnistructureVACbetter in-air "lite" access connector needed

Quote:

Quote:

 Quote: We really need something better to replace the access connector when we're at air.  This tin foil tunnel crap is dumb.  We can't do any locking in the evening after we've put on the light doors.  We need something that we can put in place of the access connector that allows us access to the OMC and IOO tables, while still allowing IMC locking, and can be left in place at night.

It is in the shop. It will be ready for the next vent. Koji's dream comes through.

Can we see the full design?  If we can't lock the mode cleaner with this thing on then it's really of no use.  We want it to be equivalent to the light doors, but allow us to keep the mode cleaner locked.  That's the most important aspect.

It also needs to be wide enough that the MMT beam can go through, so that we can not only lock the MC, but also work on the rest of the IFO.

7952   Tue Jan 29 10:59:37 2013 lazy personFrogsGeneralbetter plan

I propose we work around this problem with giant flip-flops.  These are in the vein of the take-off-your-shoes-and-put-on-Crocs, without the taking off your shoes part.  They're a little annoying on the sticky mats, but otherwise great.  They are also super easy to put on and take off without hands, so there's no excuse for wearing them around the control room.

I propose we buy many pairs of the smalls in green (since we already have one green small...they are big on me, so should be just right for most people), and a few mediums in, say, blue, and a few larges in black, and then maybe a few extra larges in green for people with extraordinarily large feet (they only have 3 colors).  Then we can keep a few pairs of each by each door to the lab, and have no more tracking dirty control room filth into the lab.

2670   Fri Mar 12 17:08:22 2010 steveConfigurationVACbg-RGAscan at d18

RGA scan of rga-region only at day 18   This is the back ground of the rga with some calibration gas.

Attachment 1: bg-d18_20100312scan.png
ELOG V3.1.3-