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ID Date Author Type Category Subject
  6911   Wed Jul 4 17:33:04 2012 JamieUpdateCDStiming, possibly leap second, brought down CDS

I got a call from Koji and Yuta that something was wrong with the CDS system.  I somehow had an immediate suspicion that it had something to do with the recent leap second.

It took a while for nodus to respond, and once he finally let me in I found a bunch of the following in his dmesg, repeated and filling the buffer:

Jul  3 22:41:34 nodus xntpd[306]: [ID 774427 daemon.notice] time reset (step) 0.998366 s
Jul  3 22:46:20 nodus xntpd[306]: [ID 774427 daemon.notice] time reset (step) -1.000847 s

Looking at date on all the front end systems, including fb, I could tell that they all looked a second fast, which is what you would expect if they had missed the leap second.  Everything syncs against nodus, so given nodus's problems above, that might explain everything.

I stopped daqd and nds on fb, and unloaded the mx drivers, which seemed to be showing problems.  I also stopped nodus's xntp:

  sudo /etc/init.d/xntpd stop

His ntp config file is in /etc/inet/ntp.conf, which is definitely the WRONG PLACE, given that the ntp server is not, as far as I can tell, being controlled by inetd.  (nodus is WAY out of date and desperately needs an overhaul.  it's nearly impossible to figure out what the hell is going on in there).  I found an old elog of Rana's that mentioned updating his config to point him to the caltech NTP server, which is now listed in the config, so I tried manually resyncing against that:

  sudo ntpdate -s -b -u

Unfortunately that didn't seem to have any effect.  This was making me wonder if the caltech server is off?  Anyway, I tried resyncing against the global NTP pool:

  sudo ntpdate -s -b -u pool.ntp.org

This seemed to work: the clock came back in sync with others that are known good.  Once nodus time was good I reloaded the mx drivers on fb and restarted daqd and nds.  They seemed come up fine.  At this point front ends started coming back on their own.  I went and restarted all the models on the machines that didn't (c1iscey and c1ioo).  Currently everything is looking ok.

I'm worried that there is still a problem with one of the NTP servers that nodus is sync'ing against, and that the problem might come back.  I'll check in again later tonight.

  6910   Tue Jul 3 20:51:06 2012 yutaUpdateIOOMC in vacuum is back

MC came back to the state as it was before the vent.

What I did:
  1. Removed beam attenuating setup on PSL table(see elog #6892).

  2. Removed 100% reflection mirror before the MC reflection PD and put 10% BS back, so that we can have MC WFS. Also, I changed C1:IOO-MC_RFPD_DCMON.HOPR to 5.

  3. Removed autolockMCmain40m_low_power from crontab on op340m, and put autolockMCmain40m again.

  4. Aligned MC and ran /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets to adjust WFS offsets.

  5. Measured beam spot positions. They looked same as before the vent.

# filename    MC1pit    MC2pit    MC3pit    MC1yaw    MC2yaw    MC3yaw    (spot positions in mm)
./dataMCdecenter/MCdecenter201206290135.dat    2.914584    4.240889    2.149244    -7.117336    -1.494540    4.955329    before vent
./dataMCdecenter/MCdecenter201207011253.dat    3.294659    3.416584    2.620511    -6.691800    -3.164084    4.806517    after vent
./dataMCdecenter/MCdecenter201207032009.dat    3.737099    3.994597    3.087857    -6.442053    -0.992543    4.714607    after pumping (now)

  6. I also turned on high voltage power supplies for input and output PZTs

  7. Below is captured Sensoray images of the current state.

  I will go on to check if IFO works as it was before or not, but I think we should center MC beam spot positions and see if we can avoid clipping in the near future.

  6909   Tue Jul 3 19:04:59 2012 JamieUpdateGreen LockingLaseroptik dichroic optics received

I put them in the "visible optics" drawer of the newish, metal optics cabinet with the thin drawers down the Y arm.

  6908   Tue Jul 3 18:58:14 2012 YaakovUpdateSTACISMore transfer functions and netGPIB status

I'm still having issues with the STACIS oscillating uncontrollably with the slightest extra vibration, but with some more added weight both x and z direction are stable if you don't disturb the setup.

I took more transfer functions of the STACIS. In the last data I took Jenne pointed out that the geophone signals were not correlated well with the driving signal, so I increased the amplitude of the driving signal and am looking in x and y too instead of just z. 

Details of the driving signal: 25 mV, swept sine from 0.1 to 100 Hz from the SR785. 

NOTE: The data below was all transferred from the SR785 using netGPIB, which works fine, if anyone was interested in using it.

Open loop in the y direction, taken with the y geophone (magnitude on top, phase on bottom):


Open loop in the x direction, taken with the x geophone (with some extra weight to try to make the closed loop more stable):


Open loop in the x direction, taken with accelerometer instead of geophone:


  6907   Tue Jul 3 17:56:35 2012 JamieUpdateGreen LockingLaseroptik dichroic optics received

We have received the dichroic optics from Laseroptik.  The coatings are:


  • 532nm: T(s+p) > 97%
  • 1064nm:  R(p) > 99.9%


  • 532nm: R(s+p) < 1%
  • 1064nm: R(p) < 2%

We got two sets with these coatings:

  • 6x: 50 x 9.5mm, 2 degree wedge
  • 8x: 25 x 6.35mm, 2 degree wedge
  • 1x: 25 x 3mm, witness
  6906   Tue Jul 3 17:23:50 2012 steveUpdateVACpumpdown completed

Vacuum Normal State is reached in 9 hours.  CC1 =  2e-5 Torr

Aux dry pump #3 is still running.  The RGA is not pumped yet.

Attachment 1: pd72.png
Attachment 2: pd72vacnormal.png
Attachment 3: pd72at9hrs.png
  6905   Mon Jul 2 23:08:38 2012 YaakovUpdateSTACISTurning on STACIS

This past Friday I swapped out a burnt resistor on the spare STACIS unit I'm working with and powered it up. Here's the setup:


And here's what happened:

X an Y directions: When I switched from open to closed loop (making the internal geophones provide feedback), the STACIS started making a loud noise- it seemed like it was oscillating uncontrollably.

Z direction: The same thing happened in z until I added some weight to the top of the STACIS- then it quieted down, and seemed to work okay. The geophone signal dropped considerably compared to the open loop signal, which is expected if the feedback is working.

Then I tried driving the PZTs with a signal from the SR785 network analyzer. With an amplitude of tens of mV and frequencies from around .1 to 200 Hz, I could see the accelerometers I mounted on top of the STACIS definitely register motion, which means I was successfully driving the PZTs.


Below are transfer functions of the STACIS as I drove the PZTs from .1 to 100 Hz at 10 mV. The top graph is open loop, the second is closed loop. These were measured with the internal geophones.

In the bottom graph, "A" is closed loop and "B" is open loop, where the transfer functions were taken with the accelerometers instead of the geophones.





Attachment 2: geo_closed.GIF
  6904   Mon Jul 2 18:28:09 2012 JenneUpdatePhotosMany photos taken

Many photos were taken by many different people....most of the fuzzy ones are by yours truely (doing a reach-around to get to hard-to-reach places), so sorry about that.

I put all the photos from yesterday and today into 6 new albums on Picasa:  https://picasaweb.google.com/foteee

The album titles are generally descriptive, and I threw in a few comments where it seemed prudent.

Big note:  The tip tilt on the ITMX table does, in fact, have the arrow pointing in the correct direction.  Photo is in the TT album from today.

  6903   Mon Jul 2 18:27:25 2012 yutaUpdateGeneralBS and ITMX chambers closed

[Koji, Steve, Jamie, Jenne, Yuta]

We opened BS and ITMX chambers, took lots of photos, and closed them with heavy doors.
I turned off high voltage power supplies for PZTs and blocked PSL beam. We are ready for the pumping tomorrow.

Important photos we took:
  - positions of green optics at BS chamber, which was moved on the vent on Aug 2011
  - positions of PZT mirrors and cable connectors at BS chamber, which will be replaced with tip-tilts on the next vent
  - arrow on PR2 pointing HR (it was correct)
  - tried to take photos of clipping IR beam at BS OSEM holder from ITMX chamber
 We also took bunch of other photos.

Beam dump needed at BS chamber:
  We also checked some un-dumped beams at BS chamber. We need dumps;
  - behind MMT1, for unwanted transmitted beam
  - behind IPPOSSM3, for unwanted transmitted beam (IPPOSSM3 is the last mirror in BS chamber for IPPOS)

  6902   Mon Jul 2 10:45:25 2012 JenneSummaryGeneralclipping at BS


No significant change was found inside the vacuum. We still see clipping at the Faraday, and also, we saw clipping by BS coil holder. Using PZT1, we could make it better, but this might be causing PRC problem -- BS is inside the PRC, too.

 Yuta just told Jamie and I that when he and Koji were looking at things yesterday, they saw that the beam spot was roughly at the center of the PRM, but was clipping on the lower OSEM holder plate on the BS.  This indicates that the beam spot on the BS is much too low.  The easiest way I can see this happening is poor pitch pointing with the tip tilts, which we unfortunately don't have active control over.

Recall elog 3425, where I mentioned some pretty bad pitch pointing after a TT was moved from the cleanroom, to the chamber, back to the cleanroom.  I think that we may need to check the pitch pointing at the chamber before installing tip tilts in the future.

  6901   Mon Jul 2 00:41:13 2012 ranaSummaryGeneralclipping at BS, my plan


 Start pumping on Monday before Steve goes home.

  6900   Sun Jul 1 23:48:15 2012 yutaSummaryGeneralclipping at BS, my plan

[Koji, Yuta]

We aligned PRMI and inspected BS chamber. Last inspection by Jamie and I (see elog #6897) was done when nothing is aligned, so I wanted to see the difference.
Aligning PRMI at low power was difficult for me, because I see no fringe at ASDC PD nor REFLDC PD. I just aligned them by looking at AS/REFL camera. The beam shape at AS looked as bad as when the usual power.

No significant change was found inside the vacuum. We still see clipping at the Faraday, and also, we saw clipping by BS coil holder. Using PZT1, we could make it better, but this might be causing PRC problem -- BS is inside the PRC, too.

We also took some pictures of PR3 and PRM(attached). The arrow pointing HR is correctly pointing inside the PRC. Seeing is believing.

Yuta's plan:
  We might have to avoid clipping at BS (and Faraday) by aligning input optics inside the vacuum. If we are going to align them, I think we should start from centering MC beam spot positions and the whole alignment could take more than a week. I don't want to spend too much time on the alignment. Also, we are going to install tip-tilts on the next big vent, so we have to redo the alignment anyway.
  So, my plan is as follows;

1. Take lots of photos and close the door on Monday(June 2).

2. Pump on Tuesday(June 3).

3. Restart working on ALS. For example, demonstration of FPMI using ALS.

4. We also can do some characterization of PRC, like measuring power recycling gain for PRMI/PRFPMI, mode scan for PRC using AUX laser from AS port, and so on. We need some calculation for clipping tolerance, too.

  Any objections?

Attachment 1: PR3.JPG
Attachment 2: PRM.JPG
  6899   Sun Jul 1 13:20:09 2012 yutaUpdateIOOMC in low power

I modified autolocker for MC in low power mode (/opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m_low_power) to make it work with the current directory structure.
autolockMCmain40m_low_power currently runs on op340m and it is in crontab.

34 * * * *  /opt/rtcds/caltech/c1/scripts/general/scripto_cron /opt/rtcds/caltech/c1/scripts/MC/autolockMCmain40m_low_power >/cvs/cds/caltech/logs/scripts/mclock.cronlog 2>&1

MC intra-cavity power:
  Currently, incident beam to the MC measured at PSL table is ~15 mW. Reflected power from MC (C1:IOO-MC_RFPD_DCMON) is 0.94 when MC unlocked, and is 0.088 when locked.
  That means, considering MC1/3 power transmission is 2000ppm (calculated finnesse=1570), intra-cavity power in MC is ~7 W.

  15 mW * (0.94-0.088)/0.94 / 2000ppm = 7 W

  We can increase the power by factor of ~2, if needed.

MC beam spot positions:

  I aligned MC to maximize transmission (C1:IOO-MC_TRANS_SUM_ERR), and measured the MC beam spot posisions in atm, low power.

# filename    MC1pit    MC2pit    MC3pit    MC1yaw    MC2yaw    MC3yaw    (spot positions in mm)
./dataMCdecenter/MCdecenter201206290135.dat    2.914584    4.240889    2.149244    -7.117336    -1.494540    4.955329    before vent
./dataMCdecenter/MCdecenter201207011253.dat    3.294659    3.416584    2.620511    -6.691800    -3.164084    4.806517    after vent

  They look the same within the error of the measurement, except for the spot positions on MC2, which we don't care.

Autolocker should be refined:
  To make autolockMCmain40m_low_power, I copied autolockMCmain40m and just changed

- lockthresh from 500 to 100
- use mcdown_low_power instead of mcdown
- use mcup_low_power instead of mcup

  The difference between mcdown_low_power and mcdown should be only

- ezcawrite C1:IOO-MC_REFL_GAIN 31 for lowpower, 9 for usual
- ezcawrite C1:IOO-MC_VCO_GAIN 10 for lowpower, -5 for usual

  The difference between mcup_low_power and mcup should be only

- ezcawrite C1:IOO-MC_REFL_GAIN 31 for lowpower, 12 for usual
- ezcawrite C1:IOO-MC_VCO_GAIN 31 for lowpower, 25 for usual

  Currently, they are not like that. Somebody good at shell scripts should combine them and make it into one code with an option something like usual/low-power.

  6898   Sat Jun 30 18:31:38 2012 steveUpdateIOOinput telescope beam clipping on Faraday

  We could set up a simple pick  off after the Faraday  and bring it  out the north window of IOO chamber. No monitor needed, just take the cover off when you want to see it.

Most people have no idea how to get the MC through the F

  6897   Fri Jun 29 22:56:35 2012 JamieUpdateVACinput telescope beam clipping on Faraday

[Yuta, Koji, Jamie]

We went into ITMX chamber to inspect the situation there.  We looked for clipping and flipping at PR2, and found none, although we noticed that the beam at PR2 looks a little clipped.

We then went back into the BS chamber and took a closer look at the beam incident on PRM, and the situation with PR3.  The PRM incident beam looked a little clipped, which we expected from the PR2 observation.  But the beam looks well centered on PRM and PR3.  As best I could tell the beam is reflecting off the front surface of PR3, as expected.

Looking at the beam around MMT1 and PJ2 (the second PZT on BS), we could tell that the beam incident and reflected off of MMT1 looked round, where as the beam incident on PJ2 looked clipped.  Using my tallness super power I was able to reach into the IMC chamber and confirm that the beam going from MMT1 to MMT2 clips fairly badly on the edge of the Faraday.   Koji speculates that this is the result of a misalignment of the PSL output beam into the MC.  In any event, it's not clear how this would be the cause of our PRC woes.

We decided to close up for the night, and let Yuta work on aligning PRMI.  We need to figure out what the heck to do now.

We've been watching the input power reduce, from 18 mW initially when we first went in, to about 5mW now.  It seems to be leveling out now.  It's unclear what would have been causing it.  Drift of the input polarization?

  6896   Fri Jun 29 16:41:41 2012 yutaUpdateGeneralPRM was NOT installed backwards

[Koji, Steve, Jamie, Yuta]

So, PRM was NOT flipped......

We opened the BS chamber and quickly checked the arrow on the PRM pointing HR. It turned out to be correct, the arrow was pointing towards the arm cavity. We opened the ITMX chamber, too, to check PR2 later.
BS chamber and ITMX chamber is now closed with the light door.

But it was a one step forward anyway, because we could prove PRM was innocent.

What to do next:
  We know that the mode-matching of the incident beam and both arms are pretty good. So, dirty modes come from PRC.
  We will check beam clipping, mirrors, suspensions in PRC.
  I expect the chambers to be closed on Monday(July 2) afternoon and start pumping on Tuesday(July 3) morning.

  6895   Fri Jun 29 13:11:31 2012 steveUpdateVAC40m IFO at atm

 The 4 hrs vent plot at 3 torr/min rate.

Nitrogen was used from 1e-6 torr to 35 torr  at intake pressure 14 PSI

The rest was filled with 5 cylinders of Instrument Grade Air at intake pressure 14 PSI

We can start opening chamber at 3 pm today


Attachment 1: vent06292012.png
Attachment 2: 40m@ATM.png
  6894   Fri Jun 29 11:02:00 2012 steveUpdateVACthe vent is at 500 torr


 Steve, Yuta and Jamie

Jam nuts were checked and oplev servos were turned off. Sus summery is below with strain gauge values. Are the strain gauge values have any meaning when the PZT contorrels are off??????????????????

Attachment 1: sussum.png
Attachment 2: pzt.png
  6893   Fri Jun 29 03:21:32 2012 yutaUpdateGeneralprep for the vent - others

1. Turned off high voltage power supplies for PZT1/2 (input PZTs) and OMC stage 1/2. They live in 1Y3 rack and AUX_OMC_NORTH rack.

2. Restored all IFO optics alignment to the position where I aligned this afternoon (for SRM, I didn't aligned it; it restored at the saved value on May 26).

3. Centered all the oplevs. They can be used for a reference for alignment change before and after the vent.

I will leave PSL mechanical shutter and green shutters closed just in case.

Some MEDM screenshots below.

  6892   Fri Jun 29 02:17:40 2012 yutaUpdateIOOprep for the vent - beam attenuating

[Koji, Jamie, Yuta]

We attenuated the incident beam (1.2 W -> 11 mW) to the vacuum chamber to be ready for the vent.
The beam spot on the MC mirrors didn't changed significantly, which means the incident beam was not shifted so much.

What we did:
 1. Installed HWP, PBS(*) and another HWP between the steering mirrors on PSL table for attenuating the beam. We didn't touched steering mirrors(**), so the incident beam to the IFO should be recovered easily, by just taking HWPs and PBS away. The power to the MC was reduced from 1.2 W to 11 mW.

(*) We stole PBSO from the AS AUX laser setup.
(**) Actually, we accidentally touched one of the steering mirrors, but we recovered them. We did the recovery tweaking the touched nob and minimizing the MC reflection. We confirmed the incident beam was recovered by measuring MC beamspot positions(below).

 2. Aligned PBS by minimizing MC reflection, adjusted first HWP so that the incident beam will be ~10 mW, and adjusted last HWP to minimize MC reflection (make the incident beam to the MC be p-polarization).

 3. To do the alignment and adjusting, we put 100% reflection mirror (instead of 10% BS) for the MC reflection PD to increase the power to the PD. That means, we don't have MC WFS right now.

 4. Tweaked MC servo gains to that we can lock MC in low power mode. It is quite stable right now. We didn't lose lock during beam spot measurement.

 5. Measured beam spot positions on the MC mirrors and convinced that the incident beam was not shifted so much (below). They look like they moved ~0.2 mm, but it is with in the error of the MC beam spot measurement.

# filename      MC1pit  MC2pit  MC3pit  MC1yaw  MC2yaw  MC3yaw  (spot positions in mm)
./dataMCdecenter/MCdecenter201206281154.dat     3.193965        4.247243        2.386126        -6.639432       -0.574460       4.815078    this noon
./dataMCdecenter/MCdecenter201206282245.dat     3.090762        4.140716        2.459465        -6.792872       -0.651146       4.868740    after recovered steering mirrors
./dataMCdecenter/MCdecenter201206290135.dat     2.914584        4.240889        2.149244        -7.117336       -1.494540       4.955329    after beam attenuation

 6. Rewrote matlab code sensemcass.m to python script sensemcass.py. This script is to calculate beam spot positions from the measurement data(see elog #6727). I think we should make senseMCdecenter script better, too, since it takes so much time and can't stop and resume the measurement if MC is unlocked.

  6891   Fri Jun 29 01:49:36 2012 yutaBureaucracyLockingvent for PRC check, TOMORROW!


 What do you mean by PR2, PR3 flipping?  They are (supposed to be) flat mirrors, so obviously they should be installed correctly, but they won't change the mode matching in a huge way if they're backwards, right?

We see some ghost beam spots at POP. This may come from the back of PR2 and PR3. Also, they may change mode matching because of thermal lensing, mirror deformation, and other unexpected reasons. I thought we should check every mirrors in PRC, if PRM is not flipped.

We are going to check PRM just because we spent so much time for the PRC problem, and still don't have the solution or evidence.
PRM flipping is kind of the only idea for the root of all evil -- terrible beam shape, low PR gain, unstable PRMI lock.
So, I want to check with my eye during the stay.

I don't think we have to redo magnet gluing. It's okay to leave them on HR side.

  6890   Thu Jun 28 22:08:57 2012 JenneBureaucracyLockingvent for PRC check, TOMORROW!


Check List:
 We will just open the BS chamber.
  - PRM flipping
  - PR2, PR3 flipping
  - PRC suspensions
  - Cipping check in PRC

 What do you mean by PR2, PR3 flipping?  They are (supposed to be) flat mirrors, so obviously they should be installed correctly, but they won't change the mode matching in a huge way if they're backwards, right?

For the PRM, I recommend checking (a) the arrow inscribed on the thinner side of the optic and (b) that the arrow *actually* points to the HR side.  I'm pretty sure I installed all the optics with the arrow pointing away from the OSEMs, but I never did a thorough check that the arrow always actually pointed to the HR coated side.  I don't remember any optics where I said "hmmm, that's funny, the arrow is pointing backwards", but nor did I write down that I had checked.

Also, hopefully the PRM is correct.  If however it's not, that means that all of the magnets are glued onto the HR side, and we'll have to redo all of the magnet gluing.  The guiderods should be fine, but all 6 magnets would need redoing.  If we were very, very careful and didn't break any of the magnets off of the dumbbells, it's a 24 hour turnaround due to drying time.  Since inevitably we break magnets away from dumbbells, conservatively we should think about a 48 hour turnaround. 

  6889   Thu Jun 28 20:59:28 2012 yutaBureaucracyLockingvent for PRC check, TOMORROW!

Koji, Jamie and I talked together and I decided to VENT TOMORROW MORNING. Main purpose of this vent is to see if PRM is flipped or not.

Vent schedule:
June 28 (Thu)
  Prepare for the vent tonight

June 29 (Fri)
  Start vent in the morning
  Look into PRC in the evening. If PRM was flipped, we will correct them. We'll use REFL to align the PRM. If PRM was not flipped, look into PR2,PR3 and other related optics.

June 30 (Sat)
July 1 (Sun)
  Thinking time. I can work if needed.

July 2 (Mon)
  If we need something else to do, do it.
  If not, start pumping.
  July 4th is the Independence Day. So, I need IFO working before July 4th.

Check List:
 We will just open the BS chamber.
  - PRM flipping
  - PR2, PR3 flipping
  - PRC suspensions
  - Cipping check in PRC

  6888   Thu Jun 28 15:21:02 2012 ranaUpdateLockingPRMI work started, commissioning plan


 Cycling the vacuum is easy. Why not vent starting Thursday evening and pop the doors on Friday morning? Inspect on Friday and pump on Monday morning.

  6887   Thu Jun 28 01:44:57 2012 KojiUpdateLockingPRMI work started, commissioning plan

To be fair, this is Kiwamu's idea. And nothing is reasonable before it is confirmed quantitatively.


Koji's idea of flipped-PRM seems reasonable, so I think we should better measure something to prove this.

  6886   Thu Jun 28 00:50:48 2012 yutaUpdateLockingPRMI work started, commissioning plan

My goal for tonight was to lock PRMI,
 grasp the current situation by my eye,
  and capture some images using Sensoray.

They are done, but what are we going to do to solve the problem? The beam looks terrible than I had expected.

What I did:
  1. DC output of POP55 PD was plugged out from 1Y2 rack, so we plugged it in.

  2. Aligned POP beam to POP25 PD and moved POP camera position at ITMX table.
  3. Mis-aligned PRM and SRM, aligned both arms, aligned FPMI as usual.

  4. Mis-aligned PRM and ETMs, aligned MI and locked MI.

  5. Aligned PRM, and carrier locked PRMI. PRM alignment was not saved since June 7, so slider values which give good alignment was pretty much drifted (~0.4 in C1:LSC_PRM_(PIT|YAW)_COMM).

  6. Took some images of POP, REFL, AS during PRMI lock.


PRMI commissioning plan:
  From the beam shape at POP, REFL, and AS, the problem clearly comes from the mode-matching, including clipping, longitudinal mismatch, and alignment mismatch. Koji's idea of flipped-PRM seems reasonable, so I think we should better measure something to prove this.
  To prove this,

  1. Simulate what the beam look like in POP, REFL, AS if PRM was flipped. Compare them with actual captured images. I need to study on unstable cavities.
  2. Calculate power recycling gain and compare.
  3. Misalign PRM and capture the image of primary, secondary, ... reflections like Koji did in elog #6421. Measure the beam sizes of these reflections using some image analysis(Python Imaging Library? Is there anyone good at this?) and calculate PRM curvature.
  4. Can we do come characterization by making PRM-ITMY cavity? ITMX will be mis-aligned, BS will be the loss port to PRC.
  5. Beamspot on POP, REFL, AS looks woblby when PRMI is locked. Why?
  6. Open the vaccum chamber and see PRM. Simple.

  Any other ideas? I have to lock PRFPMI, at least, by July 13!

  6885   Wed Jun 27 23:54:21 2012 yutaUpdateComputer Scripts / Programsimage capturing script

Mike J. came tonight and he fixed Sensoray (elog #6645). He recompiled it and fixed it.

I made a python wrapper script for Sensoray scripts. It currently lives in /users/yuta/scripts/videocapture.py.
If you run something like
  ./videocapture.py AS
it saves image capture of AS to /users/yuta/scripts/SensorayCapture/ directory with the GPS time.
Below is the example output of AS when MI is aligned. We still see some clipping in the right. This clipping is there when one arm is mis-aligned and clipping moves together with the main beam spot. So, this might be from the incident beam, probably at the Faraday.

Currently, videocapture.py runs only on pianosa, since Sensoray 2253S is connected to pianosa. Also, it can only capture MON4. My script changes MON4 automatically.


  6884   Wed Jun 27 16:23:12 2012 yutaUpdateIOOAS and REFL on AP table aligned

I touched steering mirrors for AS and REFL at AP table.
AS beam and REFL beam now hits cameras at center and their respective PDs.

What I did:
  1. Aligned Y arm and X arm.

  2. Locked FPMI and aligned BS + X arm by minimizing ASDC (DC output of the AS55 PD, C1:LSC-ASDC_OUT reached ~ -1.43).

  3. Put -2V offset to the OMC stage 2 in yaw to avoid AS clipping. The offset is currently given by SRS DS345 on AUX_OMC_NORTH rack.

  4. Misaligned ETMs, locked MI in the bright fringe. Maximized ASDC (C1:LSC-ASDC_OUT reached ~ 1.22) by aligning 2 mirrors right after the vacuum chamber. This also centered beam spot on the AS camera.

  5. Locked MI in the dark fringe. Maximized REFLDC (DC output of the REFL55 PD, C1:LSC-REFLDC_OUT reached ~ 2.5) by aligning 2 mirrors after the vacuum chamber. Beam spot on the REFL camera was centered, too.

  6883   Wed Jun 27 15:10:34 2012 JamieUpdateComputer Scripts / Programs40m summary webpages move

I have moved the summary pages stuff that Duncan set up to a new directory that it accessible to the nodus web server and is therefore available from the outside world:


which is available at:


I updated the scripts, configurations, and crontab appropriately:



  6882   Wed Jun 27 14:18:30 2012 Yaakov SummarySTACISFirst week summary

The beginning of my first week was spent at various orientations and safety meetings, some for general SURF and some more specific to LIGO and the lab. In between these I started  work.

Jenne and I took out the spare STACIS and took it apart, taking out the circuit boards. I've spent some time looking through the boards and sketching various parts of the board in trying to understand the exact function without any useful technical diagrams (STACIS supplied us only with a picture of the board without components, not all that helpful). I think I now at least understand the basic block diagram of the circuitry: the STACIS geophone signal goes through a preamplifier and filters (the semi-circular board), and converts it into a signal for the PZT stacks. This signal then goes through a high voltage amplifer, and then goes to the five PZTs (3 in the z, one each in the x and y direction). The unit I am looking at has an extension board, which allows us to tap into the signal going into the preamp and the one leaving it. This should allow us to input our own signal instead of the geophone signal, and thereby drive the PZTs ourselves.

My next step, once I get a resistor to replace a burnt one on the high voltage amplifier, is to take a transfer function of the STACIS and see if it is possible to drive the PZT stacks with the cables from the extension board. If that does not work, I'll have to keep tracing the circuit to determine where to input our own signal.

  6881   Wed Jun 27 14:12:44 2012 EricSummaryGeneralSURF Week 1

I started work familiarizing myself with the ELOG and some of the control systems at the 40m. I spent a fair bit of time gaining some general knowledge of the interferometer, control systems, calibration, null instruments, etc. On Friday, June 22 Yaakov and I spent the afternoon pulling cables for the beatbox that Jamie had finished up. We were able to get the cables from the rack containing the beatbox routed to the control room.

Then I started work on calibrating the beatbox. I set up the function generator to send a sine wave into the beatbox, then sent the signal from the beatbox to the oscilloscope. I compared both the input sine wave and the output from the beatbox at many frequencies, taking peak to peak measurements. I'm working on using the data to calibrate the beatbox now.

  6880   Wed Jun 27 11:35:06 2012 SashaSummaryComputer Scripts / ProgramsSURF - Week 1 - Summary

I started playing with matlab for the first time, accurately simulated a coupled harmonic oscillator (starting from the basic differential equations, if anyone's curious), wrote a program to get a bode plot out of any simulation (regardless of the number of inputs/outputs), and read a lot.

I'm currently going through the first stage of simulating an ideal Fabry-Perot cavity (I technically started yesterday, but yesterday's work turned out to be wrong, so fresh start!), and other than yesterday's setback, its going okay.

I attached a screenshot of my simulation of the pitch/pendulum motion of one of the mirrors LIGO uses. The bode plots for this one are turning out a little weird, but I'm fairly certain its just a computational error and can be ignored (as the simulation matlab rendered without the coupling was really accurate - down to a floating point error). I have also attached these bode plots. The first bode is based on the force input, while the second is based on the torque input. It makes sense that there are two resonant frequencies, since there ought to be one per input.


Attachment 1: Screen_Shot_2012-06-27_at_11.27.10_AM.png
Attachment 2: Screen_Shot_2012-06-27_at_11.26.57_AM.png
Attachment 3: Screen_Shot_2012-06-27_at_11.27.29_AM.png
  6879   Wed Jun 27 11:33:28 2012 MashaUpdateGeneralFirst Week Update

This week I wrote Matlab code, most of which can be found in /users/masha

First, I wrote a simulation seismicFilter.m which filters noisy seismic noise with a desired signal of non-seismic noise. The signals are purely simulated, so I played around with zero-pole-gain generation of transfer functions to obtain them. The function takes the number of taps, the filter type (Wiener or adaptive nlms) as well as an iteration step size and number of iterations, and generates PSD plots of the witness signal, the desired signal, the estimated (filtered) signal, and the error. I'm not sure that I am properly implementing the Wiener part of the code, and I assume the line "[W, R, P] = miso_firlev(TAPS, noisySeismicSignal1, seismicSignal2); " generates W, a filter with TAPS number of weights, but  then "[y, error] = filter(W, 1, noisySeismicSignal1);" generates an error signal of size TAPS rather than N, the size of the original signal. Perhaps I should calculate error using e(t) = d(t + a) - w(t)*x(t), where "a" is the delay.

I have various screenshots in my directory of what seismicFilter.m generates, and I will take a larger screenshot, as well as generate a learning curve (for error vs. number of taps) when I can use Sasha's computer for a bit, since it both has more computing power and a larger screen.

The funciton filterConvergence.m, meanwhile, is similar, except it takes two file names as real data, and uses realDataFilter.m to run the filtering. Currently, I am working with data from C1:IOO-MC_F_DQ-Online  and C1:PEM-SEIS_GUR1_X_IN1_DQ-Online, and I will include screenshots of these once I get on Sasha's computer.

In order to generate the data, meanwhile, I had to modify the python script, and thus wrote mashaImportingData.py for myself. Likewise, plotSignalFromFile.m visualizes this data, both in the time domain and in the frequency domain.

On the side, I wrote an NLMS filter in adaptiveFilterSimulationNLMS.m, and compared is to Matlab's NLMS filter in NLMStest.m (using generated data) and adaptiveFilterSimulation.m using twn input signals. Right now, it's faster on smaller inputs and smaller tap sizes, but then begins to choke and run slower than the Matlab one when these get to big. In order to improve it, I have to develop a better method of generating the initial weights.

As far as machine learning goes, once I find the number of taps for the convergence of both the Wiener filter and the NLMS filter, I will email Denis for further instructions. At some point, however, I should generate learning sets from the seismometers and the MCL (or the DARM), and thus have to find adequate times at which I can take data (probably not from the DARM, however, because it was rarely on).

Thanks for reading!

  6878   Wed Jun 27 11:27:49 2012 LizUpdate First Week Update!

This week, the other SURF students and I got acquainted with the caltech campus, LIGO 40m lab and the expectations of the SURF program.  We went to a lot of safety meetings and lectures that established a framework for the jobs we will be doing over the course of the summer.  I went on several tours of the 40m interferometer (one each with Jenne, Jamie and Steve) to get an overview of the layout and specifics of the setup.  I read parts of R. Ward and A. Parameswaran's theses and Saulson's book in order to prepare myself and gain a broader understanding of the purpose of LIGO.

I also began working in Python this week, primarily graphing PSDs of data from the C1:SUS-ETMY_SENSOR_LR, C1:SUS-ETMY_SENSOR_LL, C1:SUS-ETMY_SENSOR_UR, and C1:SUS-ETMY_SENSOR_UL channels.  I will eventually be using Python to generate the plots for the summary pages, so this is good practice.  The code that I have been working on can be found in /users/elizabeth.davison/script5.py.  Additionally, I have been going through the G1 summary pages and attempting to understand the plots available on them and the code that is available.

My plans for the upcoming week begin with modifying my code and potentially calibrating the channel data so that it is in units of length instead of counts.  I will also access the code from the G1 pages and go over it in depth, hopefully gaining insight into the structure of the website.

  6877   Wed Jun 27 10:27:09 2012 ranaSummaryIOOhow to improve mode matching to arms

The MC waist is correct as is the arm RoCs. Most likely the error is in the telescope length or its distance from the MC. Jenne probably has all the numbers and can give us a surface plot showing how the MM degrades as a function of those two parameters.

  6876   Wed Jun 27 03:43:52 2012 yutaSummaryIOOhow to improve mode matching to arms

From the mode scan measurements of the arms(elog #6859), ~6% of mode-mismatch comes from 2nd-order mode. That means we have longitudinal mismatch.

Suppose every mirrors are well positioned and well polished with designed RoC, except for the MMT1-MMT2 length. To get ~6% of mode-mismatch, MMT1-MMT2 length should be ~28cm longer (or ~26cm shorter) than designed value.
I don't know whether this is possible or not, but if they are actually longer(or shorter), we should fix it on the next vent.
I found some related elog on MMT (see #3088).


RoC and length parameters I used is below. They maybe wrong because I just guessed them. Please tell me the actual values.
Mirror thickness and effect of the incident angle is not considered yet.

== RoCs ==
MC2 19.965 m (???)
PRM 115.5 m (not used in calculation; just used to guess MC parameters)
ITM flat
ETM 57.37 m

== Lengths ==
MC round trip 27.084 m (???)
MC1 - MC3  0.18 m (???)
MC3 - MMT1 0.884+1.0442 m
MMT1 - MMT2 1.876 m
MMT2 - PRM 2.0079+0.4956 m
PRM - ITM 4.4433+2.2738 m
ITM - ETM 39 m

  6875   Tue Jun 26 22:37:43 2012 yutaUpdateIOOenergized OMC stages

[Koji, Yuta]

We checked that PZTs between SRM and OMC (called OMC stage 1 and 2) is working.
Now we need them to be EPICS channels because they are not connected to digital world right now.

  For the IFO alignment, what we have been doing for last 2weeks is,

1. Align Y arm to Y end green and maximize green transmission
2. Use PZT2 to maximize TRY (PZT1 is not functioning well. PZT1 Y do a little, but X totally does nothing.)
3. Align BS and X arm to maximize TRX
4. Tune BS and ITMX so that reflection from both arms overlap at AS
5. Align X end green to that we can see bright(~250 uW) TEM00 at transmission

  However, we found that something (Y arm axis or Y end green?) has drifted horizontally and can't make Y green transmission and TRY high level at same time. Because PZT1 is not functioning well, it is hard to compensate beam translation.
  So, now what we have to do is to align Y arm to IR incident beam. That means, we either have to realign Y end green or forget about maximizing green transmission. I think I will leave green as it is for a while because calibration of the beatbox is going on and I want to proceed to PRC.
  Anyway, if we align IFO to the IR incident beam, we see clipping in the AS port. From the contrast measurement last night, we thought clipping comes from somewhere between BS and AS port. So, we need PZTs between BS and AS port working.

What we did:
  1. Turned on 24P 24N power supplies(Sorensen DCS33-33E) in AUX_OMC_SOUTH rack to supply power to AUX_OMC_NORTH rack. 18P 18N cables to OMC_NORTH was unplugged and used by the beatbox, so we reconnected them.

  2. Turned on KEPCO high voltage power supply to supply 150 V to the PZT driver, but it was not functioning well. So, we currently use Aligent HP 6209B instead. Its on the OMC_NORTH rack.

  3. PZT driver output to OMC stage 1 was unplugged. So, we plugged them.

  4. Opened PZT driver (LIGO-D060287), put some signal from Piezo_Drive_in(J4 in schematic), and checked beamspot at AS port is moving. The gain from Piezo_Drive_in to the output (hv_out) was ~20.

  5. We could avoid clipping by putting some offset to OMC stage 2 (or 1) in yaw. That means, the clipping comes from after OMC stage 2.

  If we can control OMC stage 1 and 2, we can avoid clipping. So, we want them to be EPICS channels.

  6874   Tue Jun 26 01:30:13 2012 yutaSummaryGreen Lockingsimultaneous hold and release of the arm (aka two arm ALS)

To get the feeling of the master of IFO, I;

1. Stabilized both arm length using ALS.

2. Ran findIRresonance.py for both arms and find what offset gives me IR resonances.

3. Holded X arm to IR resonance, holded Y arm to IR resonance, and released both arms.

Below is the time series data of what I did.

 - Currently ALS is not stable enough. It only stays for about few minutes. I think it is because of the bad alignment of green from each end.
 - We can't tell end green frequency is higher or PSL green frequency is higher. So, the sign of the servo filter sometimes flips.
 - Wobbliness of X end green transmission beam spot was from the ETMX oplev. When the oplev servo is on, it got more wobbly when X end table is opened. But when the oplev servo was off, wobbliness was same even if the presence of air flow.
 - MICH contrast in plot above seems like it somehow got better when two arms are at resonance by ALS. I think this is not real because reflection from both arms at AS port was not well aligned and beam was clipped. Koji and I measured contrast of FPMI and MI(ETMs misalined), and they were 99.6 % and 99.9 % respectively. Beam clipping seems like it comes from some where between BS to AS port. We need to figure out where and fix this.

Things need to be done to make ALS more concrete:
 - Align Y end green beam!
 - Look into Y end green frequency servo
 - How do we hand-off servo using ALS to IR lock?
 - Noise budgeting for new phase tracker scheme
 - Linearity check of the beat box and phase tracker

  6873   Tue Jun 26 00:52:18 2012 yutaUpdateComputer Scripts / ProgramsPMC locker


I thought we rewrite auto lockers once per year, but this time it took us only a month. I wrote it for PMC on May 24. Is it not working?

I know.
I just wanted to use pyNDS for this kind of scanning & locking situation.
c1ioo was down for the weekend and I couldn't test my script for ALS, so I used it for PMC.

But I think PMClocker.py can relock PMC faster because it can sweep C1:PSL-PMC_RAMP continuously and can get continuous data of C1:PSL-PMC_PMCTRANSPD.

  6872   Mon Jun 25 21:54:52 2012 DenUpdateComputer Scripts / ProgramsPMC locker


I made a python script for relocking PMC.
It currently lives in /opt/rtcds/caltech/c1/scripts/PSL/PMC/PMClocker.py.

I thought we rewrite auto lockers once per year, but this time it took us only a month. I wrote it for PMC on May 24. Is it not working?

Could someone make it more clear why some scripts are written on bash, others on sh or python? I think we should elaborate a strict order. Masha and I can work on it if anyone else considers this issue as a problem.

  6871   Mon Jun 25 17:48:27 2012 yutaUpdateComputer Scripts / Programsscript for finding IR resonance using ALS

I made a python script for finding IR resonance using ALS. It currently lives in /opt/rtcds/caltech/c1/scripts/ALS/findIRresonance.py.

The basic algorism is as follows.

1. Scan the arm by putting an offset to the phase output of the phase tracker(Step C1:ALS-BEAT(X|Y)_FINE_OFFSET_OFFSET by 10 deg with 3 sec ramp time).

2. Fetch TR(X|Y) and OFFSET online data using pyNDS during the step.

3. If it finds a tall peak, sets OFFSET to the value where the tall peak was found.

4. If tall peak wasn't found, go back to 1 and step OFFSET again.

The time series data of how he did is plotted below.
I ran the script for Y arm, but it is compatible for both X and Y arm.


  6870   Mon Jun 25 16:21:10 2012 KojiSummaryIOOSelection of motorized mirror mounts

I am considering to have 3 to 6 motorized optical mounts at the PSL and end tables for remote beam steering.

Question 1:

Was there any issue on the PI 3-axis PZT on the PSL?
Why was it disabled (even before the PSL upgrade)?

Question 2:

Do we need two mount at a place? Or we do have one instead?

- Comparing the distance of the steering mirrors and that from the steering mirror to the cavity waist, induced shift
is mostly cancelled by angle adjustemnts of a either of the mounts.
i.e. Induced misalignments by the steering mirrors are nearly degenerated.

We need to move two steering mirrors only for the initial installation, but any drift felt by a cavity can be compensated by a single mirror.

Question 3:
Do we like PI-style 2 or 3 axis PZT mount with analog inputs on the HV amp?
Or do we like "Newport Agilis" style controller with USB connection?

Any opinion?

  6869   Mon Jun 25 15:19:07 2012 YaakovUpdatePEMAdded microphone channels, moved accelorometer channels

Jenne and I renamed the mic channels Den created (elog 6664) to MIC_1, MIC_2, etc from the original accelerometer names to keep things clear. We then added 6 new channels (22-27) for the accelerometers, named ACC_MC1_X, Y, Z, ACC_MC2_X, Y, Z, etc. (See the screenshot below). We also added a DAQ channel block and listed out the IN1 channel of all the sensors. We compiled and started the model, and checked that all the channels were there in DataViewer.


  6868   Mon Jun 25 15:07:49 2012 yutaUpdateIOOMC beam spot trend

I adjusted MC WFS offsets using /opt/rtcds/caltech/c1/scripts/MC/WFS/WFS_FilterBank_offsets.
Beam spot positions on MC mirrors came back to where it was past few weeks. See the trend below. Trend sometimes shows huge jump, but it's just a bad measurement caused by unlock of MC during the measurement.

I ran /opt/rtcds/caltech/c1/scripts/ASS/MC/mcassMCdecenter to measure beam spot whenever I feel like it (see elog #6727).
Beam spot doesn't move so much (~0.2 mm in standard deviation), which means incident beam from PSL table is quite stable.


  6867   Mon Jun 25 11:27:13 2012 JamieSummaryComputersc1ioo is down



I tried to restart c1ioo becuase I can't live without him.

I couldn't ssh or ping c1ioo, so I did hardware reboot.
c1ioo came back, but now ADC/DAC stats are all red.

c1ioo was OK until 3am when I left the control room last night. I don't know what happened, but StripTool from zita tells me that MC lock went off at around 4pm.

 c1ioo was still all red on the CDS status screen, so I tried a couple of things.

mxstreamrestart (which aliases on the front ends to sudo /etc/init.d/mx_stream restart) didn't help

sudo shutdown -r now didn't change anything either....c1ioo came back with red everywhere and 0x2bad on the IOP

eventually doing as Jamie did for c1sus in elog 6742, rtcds stop all, then rtcds start all fixed everything.  Interestingly, when I tried rtcds start iop, I got the error
Cannot start/stop model 'iop' on host c1ioo, so I just tried rtcds start all, and that worked fine....started with c1x03, then c1ioo, then c1gcv.

There seems to be a problem with how models are coming up on boot since the upgrade.  I think the IOP isn't coming up correctly for some reason, which is then preventing the rest of the models from starting since they depend on the IOP.

The simple way to fix this is to run the following:

ssh c1ioo
rtcds restart all

The "restart" command does the smart thing, by stopping all the models in the correct order (IOP last) and then restarting them also in the correct order (IOP first).

  6866   Mon Jun 25 11:23:14 2012 JenneUpdateComputerstdsavg not working


LSCoffsets script, and any others depending on tdsavg will not work until this is fixed.

 LSCoffsets is working again. 

tdsavg (now, but didn't used to) needs "LIGONDSIP=fb" to be specified.  Jamie just put this in the global environment, so tdsavg should just work like normal again.

Also, the rest of the LSCoffsets script (really the subcommand offset2) was tsch syntax, so I created offset3 which is bash syntax.

Now we can use LSCoffsets again.

  6865   Mon Jun 25 10:35:59 2012 JenneSummaryComputersc1ioo is down


I tried to restart c1ioo becuase I can't live without him.

I couldn't ssh or ping c1ioo, so I did hardware reboot.
c1ioo came back, but now ADC/DAC stats are all red.

c1ioo was OK until 3am when I left the control room last night. I don't know what happened, but StripTool from zita tells me that MC lock went off at around 4pm.

 c1ioo was still all red on the CDS status screen, so I tried a couple of things.

mxstreamrestart (which aliases on the front ends to sudo /etc/init.d/mx_stream restart) didn't help

sudo shutdown -r now didn't change anything either....c1ioo came back with red everywhere and 0x2bad on the IOP

eventually doing as Jamie did for c1sus in elog 6742, rtcds stop all, then rtcds start all fixed everything.  Interestingly, when I tried rtcds start iop, I got the error
Cannot start/stop model 'iop' on host c1ioo, so I just tried rtcds start all, and that worked fine....started with c1x03, then c1ioo, then c1gcv.

  6864   Mon Jun 25 08:21:40 2012 steveUpdateGeneralAC power disturbance on Sat


I was notified by CIT Utilities that there was a power surge or short power outage this after noon.

Lab conditions are normal:  c1ioo is down.  The south arm AC was off......I turned it back on.








Building:         CAMPUS


Date:             Saturday, June 23, 2012


Time:             3:46 P.M.


Interruption:     Electrical Power Disturbance


Contact:          Tom Brennan, x-625-395-4984    


*The City of Pasadena Water & Power Department had a 34,000-volt line event on Saturday June 23 at 3:46 p.m.  This caused a city wide disturbance on the power grid.  The Campus did not lose electrical power.  However, the disturbance may have affected sensitive electronic equipment.

(If there is a problem with this Interruption, please notify the Service Center X-4717 or the above Contact as soon as possible.

If no response is received we will proceed with the interruption.)


                        Jerry Thompson,

                        Interim Director of Campus Operations & Maintenance


Attachment 1: powerdisturbed.png
  6863   Sun Jun 24 23:42:31 2012 yutaUpdateComputer Scripts / ProgramsPMC locker

I made a python script for relocking PMC.
It currently lives in /opt/rtcds/caltech/c1/scripts/PSL/PMC/PMClocker.py.

I think the hardest part for this kind of locker is the scan speed. I could make the scan relatively fast by using pyNDS.
The basic algorithm is as follows.

1. Turns off the servo by C1:PSL-PMC_SW1.

2. Scans C1:PSL-PMC_RAMP using ezcastep.bin. Default settings for ezcastep is

ezcastep.bin C1:PSL-PMC_RAMP -s 0.1 0.01 10000

So, it steps by 0.01 for 10000 times with interval of 0.1 sec.

3. Get C1:PSL-PMC_PMCTRANSPD and C1:PSL-PMC_RAMP online 1 sec data using pyNDS.

4. If it finds a tall peak in C1:PSL-PMC_PMCTRANSPD, kills ezcastep.bin process, sets C1:PSL-PMC_RAMP to the value where the tall peak was found, and then turns on the servo.

5. If tall peak wasn't found, go back to 3 and get data again.

6. If C1:PSL-PMC_RAMP reaches near -7 V or 0 V, it kills previous ezcastep.bin process and turns the sign of the scan.

I tested this script several times. It sometimes passes over TEM00 (because of the dead time in online pyNDS?), but it locks PMC with in ~10 sec.
Currently, you have to run this to relock PMC because I don't know how to make this an autolocker.

I think use of pyNDS can be applied for finding IR resonance using ALS, too.
I haven't checked it yet becuase c1ioo is down, but ALS version lives in /users/yuta/scripts/findIRresonance.py. ALS may be easier in that we can use fast channels and nice filter modules.

Other scripts:
 I updated /opt/rtcds/caltech/c1/scripts/general/toggler.py. It now has "lazymode". When lazymode, it toggles automatically with interval of 1 sec until you Ctrl-c.

 Also, I moved damprestore.py from my users directory to /opt/rtcds/caltech/c1/scripts/SUS/damprestore.py. It restores suspension damping of a specified mirror when watchdog shuts down the damping.

  6862   Sun Jun 24 00:10:45 2012 yutaUpdateGreen Lockingcurrent beat electronics

I moved amplifiers for beat PD at PSL table to 1X2 rack. Current beat setup from PD to ADC is shown below. Setup for X beat and Y beat are almost the same except for minor difference like cable kind for the delay line.

Currently, DC power for amplifiers ZHL-1000LN+ is supplied by Aligent E3620A.
I tried to use power supply from the side of 1X1 rack, but fuse plug(Phoenix Contact ST-SI-UK-4) showed red LED, so I couldn't use it.
Measured amplification was +25 dB for 10-100 MHz.

Measured gain from RF input to monitor output of the beat box was ~ -1 db for 10-100 MHz.


ELOG V3.1.3-