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ID Date Author Type Category Subjectup
  9532   Tue Jan 7 23:09:10 2014 manasaUpdateIOOMC aligned

Quote:

[Rana, Jenne]

We turned off the WFS servos, and looked at the MC REFL DC, and saw that it was still good, so we said that since the MC spots are pretty good, that we'll keep this alignment for now. 

Rana put the beam back on the center of the IOO QPDs on the PSL table.

We switched a steering mirror in the WFS path that was the wrong handed-ness to be the correct handed-ness, then put the beam on the centers of the WFS.  We turned on the WFS, and everything seems good. 

There were no major drifts in the WFS error signals while we were gone for dinner, so the MC seems okay for now.

 The last 4 hour trend for WFS error signals show some amount of drift. We should still look at the long term trend to solve the issue.

Attachment 1: WFSdrift.png
WFSdrift.png
  3905   Fri Nov 12 06:10:24 2010 yutaUpdateIOOMC aligned (without coil balancing)

Background:
  Last night, we found that one of DAC channels are poorly connected, so we fixed the connectors.
  Rana and Koji used their incredible eyeballs to roughly align MC.
  Next thing to do is to balance the coils, but it takes some time for the setup.
  So, we decided to do A2L anyway.

What I did:
  Using the last steering mirror at PSL table and IM1, changed the incident beam direction to align MC.

Result:
MCalignCALIB.png
 
  I was amazed by their eyeballs.
  I turned the nobs of SM@PSL and IM1 in small increments, so I never lost TEM00.

Is it enough?:
  The length of the whole faraday is about 20cm and aperture diameter is about 12mm. (I couldn't measure the aperture size of the core)
  The beam is about 9mm diameter at 6w.
  So, if the beam is vertically tilted at more than ~3/200rad, it(6w) cannot go through.
  3/200 rad is about 20% difference in position at MC1 and MC3.
  So, the result meets the requirement.

  Also, assuming that coils have 5% imbalance, the beam position I measured have ~3% error.
  So, to do more precise beam centering, we need to balance the coils.

  5490   Tue Sep 20 21:13:39 2011 SureshUpdateIOOMC aligned and PSL beam into MC readjusted

This morning after Kiwamu maximised the PSL beam coupling into the MC we noticed that the MC2 face camera showed the spot position had moved away from the center by about a diameter.  So I checked the beam spot positions with MCASS and indeed found that the spot on MC2 had moved to about 6mm away from the center in yaw and about 3mm in pitch.  I adjusted the MC2 (and only MC2) to recenter the spots on all the three mirrors.  The new spot positions are given below

spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
    1.3337   -0.2660    0.6641   -1.0973    0.0468   -1.7130

The PSL beam into MC has been readjusted for maximal coupling into MC.

 

  8794   Wed Jul 3 10:39:25 2013 manasaUpdateIOOMC aligned and WFS enabled

I found WFS had been left disabled from sometime yesterday. I don't see anyone mentioning  when and why they had turned OFF the WFS servo.

I aligned MC and turned ON the WFS servo. MC is back.

  1396   Thu Mar 12 18:48:37 2009 YoichiUpdateIOOMC aligned but ...
After the MZ alignment, I aligned the MC with the periscope mirrors.
It looked like the MC mis-alignment was mainly caused by the input beam change.
So I left the MC mirrors as they were to keep the output beam pointing.
However, after I finished the alignment, the MC output beam was too low on the Faraday.
Also the X-arm did not lock to TEM00 mode. So the MC mirrors must have also shifted to a weird alignment state.
I should have restored the MC mirror alignment to a good state using the OSEM DC signals.

Rana came in and restored the MC mirror alignment using the SUS drift mon.
He and Kakeru is now working on the periscope to align the beam into the MC.
  3883   Tue Nov 9 05:40:12 2010 yutaSummaryIOOMC aligning going on

(Suresh, Yuta)

Background:
  Last week, we reduced the common mode displacement of the beam through MC1 to MC3. 
  Next work is to tilt the beam and center it.

What we did:
  1. Changed the offset going into 1201 Low Noise Amplifier(1201 is for adding +5V offset so that the feedback signal will be in the range of 0-10V)
  2. Using the last steering mirror(SM@PSL) and IM1, tilted the beam
  3. As the beam height changed alot(~0.5cm higher at IM1), MC1 reflection could not reach MCREFL PD. So, we tilted the mirror just after MC1, too.

Result:
MCalignNov9.png

Plan:

  - continue to tilt IM1 in small increments in order to reduce PIT/YAW to length coupling
      If large increments, it takes so much time re-aligning MC to get flashing!

By the way:

    The signal we kept saying "MCL" was not the error signal itself. It was a feed back signal(output of the mode cleaner servo board). The cable labeled "MC REFL" is the error signal. Compare MEDM screen C1IOO_MC_SERVO.adl and the mode cleaner servo board at 1X2. You will be enlightened.

Quote (from elog #3857):

4. Disconnected the cable labeled "MC OUT1" at 1X2 (which is MCL signal to ADC) and put MC2_ULCOIL output directly using long BNC cable.

 

  1386   Wed Mar 11 14:51:01 2009 Kakeru, Joe, RobUpdateIOOMC alignment

This morning, MC alignment was gone and MC wasn't lock.

We checked old value of pitch, yaw, and position offset of each MC mirror, and found they were jumped.

We don't know the reason of this jump, but we restore each offset value and MC backed to lock.

  2852   Tue Apr 27 22:28:58 2010 ZachUpdateIOOMC alignment

Beginning last week, I have been helping Koji with some of the IO work that must be done for the 40m upgrade. The first thing he asked me to do is to help with the alignment of the MC.

As I understand, it became apparent that the IFO beam was not centered on all (or any) of the MC mirrors, which is disadvantageous for obvious reasons. We are trying to correct this, using the following strategy:

  1. Adjust the MC mirrors into rough alignment, isolate a strong TEM00, and lock the cavity
  2. Fine-tune the alignment by minimizing the REFL power when locked (in these first two steps, we adjusted only MC2 & MC3, assuming that the REFL beam was centered on the PD, and wanting to keep it that way). At this point, the cavity is resonating some asymmetric mode, looking something like (not to scale---for illustration only):MC_misaligned.png
  3. Shake all three mirrors (in succession) in pitch and yaw, each time demodulating the error signal at the frequency used for the excitation and recording the magnitude and phase of the response.
  4. Move one mirror's DC orientation, repeat step 3, and then restore the mirror to its original position
  5. Repeat step 4 for both angular degrees of freedom of each mirror

Using the results of these measurements, it is possible to evaluate the components of a block-diagonal matrix M which relates the tilt-to-displacement coupling of each DOF to each mirror's misalignment in that degree, i.e.,

a = M x

with a a 6-dimensional vector containing the coupling of each degree of freedom to the length of the cavity and x a 6-dimensional vector containing the angular misalignments of each. Due to orthogonality of pitch and yaw, M will take the form of a 6x6 matrix with two non-zero 3x3 blocks along the diagonal and zero matrices on the off-diagonal blocks.

The idea is to isolate components of M by moving one mirror at a time, solve for them, then find the inverse M-1 that should give us the required angular adjustments to obtain the beam-centered ideal cavity mode.

In theory, this need only be done once; in practice, our measurement error will compound and M will not be accurate enough to get the beams exactly centered, so we will have to iterate.

NOTE: The fact that we are adjusting the three cavity mirrors to obtain the ideal mode means that we will necessarily tarnish our coupling into the cavity. Once we have adjusted the mirrors once, we will need to re-steer the input beam and center it on the REFL diode. 

Status: This process has been completed once through step 5. I am in the process of trying to construct the matrix for the first adjustment.

 

  2855   Wed Apr 28 12:05:44 2010 ZachUpdateIOOMC alignment

I have worked out the first set of adjustments to make on the MC mirrors (all angle figures are in units of the increments on the control screen)

Using the method described in the previous post, I obtained the following matrix relating the angle-to-length coupling and the angular deviations. In the following matrix, Mij corresponds to the contribution of the jth degree of freedom to the ith A-to-L coupling, with the state vector defined as xi = (MC1P, MC2P, MC3P, MC1Y, MC2Y, MC3Y), where each element is understood as the angular deviation of the specific mirror in the specific direction from the ideal position, such that x = 0 when the cavity eigenmode is the correct one and the beams are centered on the mirrors (thus giving no A-to-L coupling regardless of the components of M).

 

M =

   1.0e+03 *

   -0.2843   -0.4279   -0.1254         0         0         0

   -0.8903   -0.4820   -0.6623         0         0         0

    0.5024    0.0484   -0.0099         0         0         0

         0         0         0         0.1145   -0.1941   -0.3407

         0         0         0         0.0265    1.5601    0.2115

         0         0         0         0.1015    0.1805   -0.0103,

giving an inverse

M-1 =  

    0.0003   -0.0001    0.0020         0         0         0

   -0.0031    0.0006   -0.0007         0         0         0

    0.0018   -0.0018   -0.0022         0         0         0

         0         0         0        -0.0013   -0.0015    0.0117

         0         0         0         0.0005    0.0008   -0.0008

         0         0         0        -0.0037   -0.0010    0.0044

The initial coupling vector is then acted on with this inverse matrix to give an approximate state vector x containing the angular misalignments of each mirror in pitch and yaw. The results are below:

x

   1P:  0.0223

   2P: -0.0733

   3P:  0.3010

  1Y:  -0.1372

  2Y:   0.0194

  3Y:  -0.0681

 

  2856   Wed Apr 28 14:15:58 2010 AlbertoUpdateIOOMC alignment

 

 That's interesting.

Would it be possible to write about the technique on a wiki page as you get measurements and results?

  2858   Wed Apr 28 14:42:55 2010 ZachUpdateIOOMC alignment

Sure. I figured I would put up a How-To if it works. 

Quote:

 

 That's interesting.

Would it be possible to write about the technique on a wiki page as you get measurements and results?

 

  3012   Fri May 28 21:32:32 2010 AlbertoUpdate40m UpgradingMC alignment

[Alberto, Kiwamu, Kevin, Rana]

Today we tried to measured the beam shape after the MC MMT1 that Jenne installed on the BS table.

The beam scan showed a clipped spot. We tracked it down to the Farady and the MCT pickoff mirror.

The beam was getting clipped at the exit of the Faraday. But it was also clipping the edge of the MCT pick-off mirror. I moved the mirror.

Also the beam looked off-center on MC2.

We're coming back on Sunday to keep working on this.

Now things are bad.

  3013   Fri May 28 23:21:52 2010 KojiUpdateIOOMC alignment

Hm... You touched the optics between the MC and the Faraday... This will lead us to the painful work.

I am afraid that the beam is already walking off from the center of MC1/MC3 after the work on the PSL table.
This may result in the shift of the spot on those MC mirrors. So I recommend that:

- Lock the cavity
- Check the A2L for MC1/3
- Adjust it by the periscope
- If it is fine, adjust the optics after the MC (steering, Faraday, etc)

Off-centering of the MC2 spot is no problem. We can move it easily using Zach's scripts.
Tell me when the work is planed on Sunday as I might be able to join the work if it is in the evening.

Quote:

[Alberto, Kiwamu, Kevin, Rana]

Today we tried to measured the beam shape after the MC MMT1 that Jenne installed on the BS table.

The beam scan showed a clipped spot. We tracked it down to the Farady and the MCT pickoff mirror.

The beam was getting clipped at the exit of the Faraday. But it was also clipping the edge of the MCT pick-off mirror. I moved the mirror.

Also the beam looked off-center on MC2.

We're coming back on Sunday to keep working on this.

Now things are bad.

 

  3019   Mon May 31 00:10:18 2010 kiwamuUpdateIOOMC alignment

  [Alberto, Kiwamu]

The MC alignment is getting better by steering the axis of the incident beam into the MC.

We found the beam spot on MC1 and MC3 were quite off-centered in the beginning of today's work. It had the coil gain ratio of 0.6:1.4 after running the A2L script.

In order to let the beam hit the center of the MC1 and MC3, we steered the bottom mirror attached on the periscope on the PSL table to the yaw direction.

And then we got better numbers for the coil gain ratio (see the numbers listed at the bottom).

For the pitch direction, there still are some rooms to improve because we didn't do anything with the pitch. It is going to be improved tomorrow or later.

 

Here are the amounts of off-centering on MC1 and MC3 after steering the axis. 

 C1:SUS- MC1_ULPIT_GAIN =  0.900445

C1:SUS-MC1_ULYAW_GAIN =  0.981212

C1:SUS-MC3_ULPIT_GAIN =  0.86398

C1:SUS-MC3_ULYAW_GAIN =   1.03221

  3020   Mon May 31 03:38:48 2010 KojiUpdateIOOMC alignment

Remember that you only can introduce the axis translations from the PSL table.
It is quite difficult to adjust the axis rotation.

The calibration factor from A2L results to the beam position is dx = (A2L_result - 1) *10.8mm

If I believer the result below, the spot positions on the mirrors are

MC1 Pitch      -1.1mm
MC1 Yaw        -0.20mm
MC3 Pitch      -1.5mm
MC3 Yaw        +0.35mm

This means that the beam is 1.3mm too high and 0.28mm too much in north

This corresponds to tilting SM2 by
0.33mrad in pitch (23deg in CW)
and
0.10mrad in yaw (7deg in CW).

Quote:

C1:SUS-MC1_ULPIT_GAIN =  0.900445
C1:SUS-MC1_ULYAW_GAIN =  0.981212
C1:SUS-MC3_ULPIT_GAIN =  0.86398

C1:SUS-MC3_ULYAW_GAIN =  1.03221  

 

Attachment 1: MC_spot_centering.png
MC_spot_centering.png
  3903   Fri Nov 12 00:42:11 2010 rana, kojiUpdateIOOMC alignment

We decided to ignore the computer script outputs for the beam positions and use instead the eyeball method to get the beam into the MC:

  1. Adjust PSL launch beam to get the beam centered on IM1.
  2. Eyeball the beam to hit the center of MC1. We can get this pretty good by using the brackets to get the vertical and using the centering of the input/refl beams to center it horizontally.
  3. Use MC3 suspension to hit the center of MC2. We did this by hitting each of the 3 EQ stop screw heads and triangulating the MC3 bias settings.
  4. Use MC2 bias to hit the center of MC1.
  5. Use MC1 to get good flashes.
  6. Use all 3 MC sus biases to maximize the transmitted light and minimize the REFL DC.

With this rough alignment in place, we leave it to Yuta to finish the coil balancing and the A2L. We will have an aligned MC in the morning and will start the BS chamber alignment.

  6115   Wed Dec 14 01:35:06 2011 KojiUpdateIOOMC alignment craziness

~11PM I came to the 40m and found the MC is repeating "LOCK->WFS ON->UNLOCK" sequence for ~2hours.

I checked the WFS spots on the QPDs and aligned them. No luck. I suspected the clipping of the beam in the chamber.

After I checked the trends of MC SUS OSEM values and IPPOS, I concluded that the input beam was aligned to somewhat misaligned MC.

The most noticable thing was that IPPOS (X, Y) indicated about (-0.5, 0) although the recent trend shows (-1, -0.5) is nominal.
In fact, the beam was about dropping from the diode. In addition, I found that the MC2 suspension showed a jump in the morning at around 8.30AM.|
This is consistent with what Jenne described.

This was a difficult situation as everything was moved.
I used the OSEM values to come back to the previous alignment of the suspensions, and started touching Zig-Zag before the MC.
After the alignment I ended up more clipping of the MC REFL. Also the spot on the IPPOS QPD was more dropping.

So, I have empirically used MC3 to misalign in Yaw to have better spot position on IPPOS. Then, the Zig Zag was aligned.
Then the spot on MC2 was adjusted while MCTRANS was kept maximized.

This helped the things back in the normal state.

Now the WFS servo is happily controlling the alignment.
MC REFL is 4.8 and 0.47 for unlocked and locked. (MCREFL_UNLOCK was 4.6 before my touch)
MCTRANS is 27000, which is close to the nominal.
IPPOS total, x, and y are 0.36, -0.97, and -0.47, respectively. They are about the nominal.

~1AM done

HOWEVER, we still don't know the position of the spot on MC1/MC3, and ITMY and ETMY.
I should consult with Kiwamu to check the spot positions tomorrow.

General lessons:
- If you find any reduction of MC transmission, check the suspensions to see if there is any slip.
- Before touching the input optics to recover the MC alignment, we should think what was moved.
- Before touching EOM alignment you must check the MC alignment WITHOUT WFS, so that you can recover the misalignment of EOM by the Zig-Zag steering.
- WFS is sensitive to clipping of the beam.
- We need a nifty indicator to tell how the MC transmitted beam is good.

Attachment 1: Untitled.png
Untitled.png
  6118   Wed Dec 14 14:07:48 2011 KojiUpdateIOOMC alignment craziness

[Kiwamu Koji]

To check if the MC alignment is OK or not, we tried to lock the Y-arm.

Once the alignment of Y-arm was restored, we saw the resonant peak of ~0.2 in TRY.
After a small tweak of PZT2, TRY has got improved up to 0.7.

Kiwamu made a small tweak on the problematic PZT1, then the full (1.0) TRY was recovered.

Thus we concluded the current MC alignment is good enough.

  11106   Fri Mar 6 00:59:13 2015 ranaSummaryIOOMC alignment not drifting; PSL beam is drifting

In the attached plot you can see that the MC REFL fluctuations started getting larger on Feb 24 just after midnight. Its been bad ever since. What happened that night or the afternoon of Feb 23?
The WFS DC spot positions were far off (~0.9), so I unlocked the IMC and aligned the spots on there using the nearby steering mirrors - lets see if this helps.

Also, these mounts should be improved. Steve, can you please prepare 5 mounts with the Thorlabs BA2 or BA3 base, the 3/4" diameter steel posts, and the Polanski steel mirror mounts? We should replace the mirror mounts for the 1" diameter mirrors during the daytime next week to reduce drift.

Attachment 1: MCdrfit.png
MCdrfit.png
  11112   Fri Mar 6 19:54:15 2015 ranaSummaryIOOMC alignment not drifting; PSL beam is drifting

MC Refl alignment follow up: the alignment from last night seems still good today. We should keep an cool on the MC WFS DC spots and not let them get beyond 0.5.

Attachment 1: Untitled.png
Untitled.png
  11147   Thu Mar 19 16:58:19 2015 SteveSummaryIOOMC alignment not drifting; PSL beam is drifting

Polaris mounts ordered.

Quote:

In the attached plot you can see that the MC REFL fluctuations started getting larger on Feb 24 just after midnight. Its been bad ever since. What happened that night or the afternoon of Feb 23?
The WFS DC spot positions were far off (~0.9), so I unlocked the IMC and aligned the spots on there using the nearby steering mirrors - lets see if this helps.

Also, these mounts should be improved. Steve, can you please prepare 5 mounts with the Thorlabs BA2 or BA3 base, the 3/4" diameter steel posts, and the Polanski steel mirror mounts? We should replace the mirror mounts for the 1" diameter mirrors during the daytime next week to reduce drift.

 

Attachment 1: driftingInputBeam2.jpg
driftingInputBeam2.jpg
  11149   Fri Mar 20 10:51:09 2015 SteveSummaryIOOMC alignment not drifting; PSL beam is drifting

Are the two  visible small srews holding the adapter plate only?

If yes, it is the weakest point of the IOO path.

Attachment 1: eom4.jpg
eom4.jpg
Attachment 2: eom3.jpg
eom3.jpg
  9336   Mon Nov 4 12:59:43 2013 JenneUpdateIOOMC alignment not so good after PSL output shutter installed

Quote:

  The PSL shutter is reinstalled.

 I'm not sure if Steve bumped something, or if it was just a fluke, but the MC didn't come back very nicely after Steve finished re-installing the shutter.

Earlier today, after Steve locked the PMC, MC trans looked good for over an hour (according to the striptool plot on the wall).  Then, the MC was unlocked for about an hour, presumably while Steve was working, he had the light blocked.  When he finished, the MC transmission was around 5,000 while usually it is around 17,000.  The reflection was around 3.4, rather than a best of below 0.5 (unlocked refl is 4.5).

Using Rana's ezcaservo trick to get the suspensions back to where they were at last good lock usually works (I used to do it by hand though).  However, today, it only got the reflection down to about 2.0.  So, I did the rest of the alignment by hand. 

After I did this, the reflection is down to 0.48.  Engaging the WFS makes the MC much more noisy, so I have them disabled currently. 

I have measured the spots, and if I compare them to the measurements that (I think it was Manasa) took last week, they look pretty bad. 

I think that we need to swap out the 2nd zigzag mirror, and then do a careful MC realignment.  It's certainly not worth doing the work, and then re-doing it after we swap out the zigzag mirror.

MCspots_4Nov2013.png

  6426   Fri Mar 16 16:03:03 2012 kiwamuUpdateIOOMC alignment servo : put some offsets in the TRANS QPD signal

The MC alignment servo wasn't great in the last 1 hour or so as it kept disturbing the MC lock. It was found to be due to some offsets in the MC trans QPD signals.

I put some values to cancel the offsets and then the lock became stable.

This is a first aid. So we need to take a closer look at the QPD signals and also probably the spot position on the QPD.

 


The symptom was that every time the alignment servo was engaged, at the beginning the amount of the transmitted light went to 27000 counts, which is good.

However, then the amount of the transmitted light slowly decreased in a time scale of ~ 20 sec or so, ending up with destruction of the MC lock.

According to the time scale I suspected that the servos using the trans QPD signals were doing something bad because their control width had been designed to be slow and slower than the rest of the servo loops.

I switched off the servos, called C1:IOO-TRANS_PIT and C1:IOO-TRANS_YAW and found the MC stayed locked stably with 27000 counts of the transmitted light.

Leaving the trans QPD servos off, I zeroed the offsets and then switched them on. It worked.

 

The values below are the current offset that I put.

                C1:IOO-MC2_TRANS_PIT_OFFSET = -0.115203
                C1:IOO-MC2_TRANS_YAW_OFFSET = -0.0323576
 

  307   Sun Feb 10 21:43:16 2008 robConfigurationIOOMC alignment tweaked

I adjusted the alignment of the free hanging mode cleaner to best transmit the PSL beam.
  3174   Wed Jul 7 22:58:08 2010 nancyUpdateIOOMC alignment values.

Nancy and Koji:

This is what I and Koji measured after aligning the MC in the afternoon.

MC_Trans 4.595 (avg)

MC_Refl 0.203 (avg)

MC2_trans :

power = 1.34mW

13.5% width : x=6747.8 +- 20.7 um  , y = 6699.4+- 20.7 um

 

  3175   Wed Jul 7 23:11:08 2010 KojiUpdateIOOMC alignment values.

Hmm. I expect that you will put more details of the work tomorrow.
i.e. motivation, method, result (the previous entry is only this),
and some discussiona with how to do next.

Quote:

Nancy and Koji:

This is what I and Koji measured after aligning the MC in the afternoon.

MC_Trans 4.595 (avg)

MC_Refl 0.203 (avg)

MC2_trans :

power = 1.34mW

13.5% width : x=6747.8 +- 20.7 um  , y = 6699.4+- 20.7 um

 

 

  3183   Thu Jul 8 20:32:22 2010 nancyUpdateIOOMC alignment values.

I and Koji were trying to lock the mode cleaner for measuring the beam power at MC2 end. That is when we obtained the trans and refl values.

The beam characteristics at the MC2 were measured so that we could now use a dummy beam of similar power to test and characterize the QPD we are about to install at the MC2 end. This QPD wil provide two more signals in pitch and yaw, and hence complete 6 signals for 6 rotatioanl dof of the cavity. (4 are coming from WFS).

Once the QPD is characterised, it can be used to see the spot position at MC2. This is related to the mirror angles.

The width measurements were done using a beam scan. the beam scan was properly adjusted so that the maxima of the intensity of the sopt was at its center.

We also fitted gaussian curve to the beam profile, and it was a substantially good fit.

 

The whole idea is that I am trying  to look how the Wavefront sensors respond to the perturbations in the mirror angles. Once this is known, we should be able to control the mirror-movements.

the starting point would be to do just the DC measurements (which I did today). For proper analysis, AC measurements are obviously required.(will be done later).

The matrices so calculated can be inverted, and if found enough singular, the method can be used to control.

The first shot is to see teh dependency of teh error signals only on MC1 and MC3, and see if that is kind of enough to control these two mirrors.

If this works, the QPD signals could be used to control MC2 movements.

Quote:

Hmm. I expect that you will put more details of the work tomorrow.
i.e. motivation, method, result (the previous entry is only this),
and some discussiona with how to do next.

Quote:

Nancy and Koji:

This is what I and Koji measured after aligning the MC in the afternoon.

MC_Trans 4.595 (avg)

MC_Refl 0.203 (avg)

MC2_trans :

power = 1.34mW

13.5% width : x=6747.8 +- 20.7 um  , y = 6699.4+- 20.7 um

 

 

 

  4305   Wed Feb 16 01:03:59 2011 JenneUpdateIOOMC alignment work

So.... Kiwamu and I were concerned (still a little concerned) that ETMY is not damping as nicely as it should be.  (It's fine, but the UL rms is ~5, rather than ~1 or less. BURT restores by Kiwamu didn't change anything.) Anyhow, I was heading out to push the annoying ribbon cables more firmly into the satellite adapter board things that are tied to the racks in various places (The back of 1X5 for the corner optics and the end station racks for the ETMs).  The point was to push in the ETMY one, but while I was out in the lab and thinking about it, I also gave all of the corner connectors (MC1, MC2, MC3, ITMx, ITMY, BS, PRM, SRM) a firm push. 

Kiwamu noticed that when I did this, the Mode Cleaner alignment got a little bit worse, as if the connection to the satellite adapter boards hadn't been great, I pushed the connectors in and the connection got better, but we also got a bit of a DC offset in the MC alignment.  Anyhow, the MC_TRANS power went down by ~2, to about the place it had been before Kiwamu adjusted the position of the lens in between the zigzag mirrors.  (I don't know if Kiwamu elogged it earlier, but he scooted the lens a teensy bit closer in the optical path to the Mode Cleaner). 

To counteract this loss in MC transmitted power as a result of my connector actions, I went back to the PSL table and fiddled with the zigzag steering mirrors that steer the beam from the PSL table over to the mode cleaner.  I got it a little better, but it's still not perfect.

Kiwamu has noted that to improve the mode matching into the Mode Cleaner with the new PMC in place, we might have to move the lens which is currently between the zigzag steering mirrors, and put it after the second mirror (so in between the last steering mirror and the pickoff window that sends a piece of the beam over to PSL_POS and PSL_ANG).  This will make the waist between MC1 and MC3 tighter. 

Moral of the story:  To improve IMC mode matching we need to move the last lens closer in the optical path to the mode cleaner waist. Twiddle with zigzag steering mirrors to optimize.

  4316   Thu Feb 17 14:52:27 2011 JenneUpdateIOOMC alignment work

I worked a little bit more on optimizing the mode matching to the MC, but it's still not great.  I've only gotten a visibility of ~45%, but Koji said that it used to be ~87%.  So there is a long way to go.  Kiwamu said he can work with the lower-power configuration for a few days, and so my next step will be to measure the beam profile (stick a window in the path, and look at the refl from the window....that way we don't get thermal lensing from transmission through an optic), and redo the mode matching calculation, to figure out where the last lens should actually sit.

Quote:

So.... Kiwamu and I were concerned (still a little concerned) that ETMY is not damping as nicely as it should be.  (It's fine, but the UL rms is ~5, rather than ~1 or less. BURT restores by Kiwamu didn't change anything.) Anyhow, I was heading out to push the annoying ribbon cables more firmly into the satellite adapter board things that are tied to the racks in various places (The back of 1X5 for the corner optics and the end station racks for the ETMs).  The point was to push in the ETMY one, but while I was out in the lab and thinking about it, I also gave all of the corner connectors (MC1, MC2, MC3, ITMx, ITMY, BS, PRM, SRM) a firm push. 

Kiwamu noticed that when I did this, the Mode Cleaner alignment got a little bit worse, as if the connection to the satellite adapter boards hadn't been great, I pushed the connectors in and the connection got better, but we also got a bit of a DC offset in the MC alignment.  Anyhow, the MC_TRANS power went down by ~2, to about the place it had been before Kiwamu adjusted the position of the lens in between the zigzag mirrors.  (I don't know if Kiwamu elogged it earlier, but he scooted the lens a teensy bit closer in the optical path to the Mode Cleaner). 

To counteract this loss in MC transmitted power as a result of my connector actions, I went back to the PSL table and fiddled with the zigzag steering mirrors that steer the beam from the PSL table over to the mode cleaner.  I got it a little better, but it's still not perfect.

Kiwamu has noted that to improve the mode matching into the Mode Cleaner with the new PMC in place, we might have to move the lens which is currently between the zigzag steering mirrors, and put it after the second mirror (so in between the last steering mirror and the pickoff window that sends a piece of the beam over to PSL_POS and PSL_ANG).  This will make the waist between MC1 and MC3 tighter. 

Moral of the story:  To improve IMC mode matching we need to move the last lens closer in the optical path to the mode cleaner waist. Twiddle with zigzag steering mirrors to optimize.

 

  7557   Tue Oct 16 11:54:05 2012 JenneUpdateIOOMC alignment??

The MC won't survive the boosts right now.  Pizza meeting is in a minute, and I won't be back to the lab before ~3:30 because of the seminar / a meeting, so someone else is welcome to try to fix it. Otherwise I'll have a look later on.

I'm leaving the autolocker disabled, so that it won't try any funny business.  WFS are off, so that they don't need to be turned off by the down script.

  9898   Fri May 2 02:22:56 2014 rana, QUpdateIOOMC alignments

We were having unstable MC locking so we did some physical alignment touch up. Use MC suspension bias to have good MC alignment. Unlock MC and align DC beams to center on WFS. Re-lock and things are now stable.

Someone had been feeding bad info to Eric about MC alignments; we do not center the MC WFS beams with the MC locked.

However, in any case, today the MC2-TRANS servo was not being good so I turned it off. We need the real matrix measurement to bring it back.

  8281   Wed Mar 13 02:48:13 2013 JenneUpdateIOOMC all better

Koji reminded me (again....this is probably the  2nd or 3rd time I've "discovered" this, at least) that the script

..../scripts/MC/WFS/WFS_FilterBank_offsets

exists, and that we should use it sometimes.  See his elog 7452 for details. 

 

Notes about using this script:

* Only use it after MC has been very well aligned.  MC REFL DC should be less than 0.5 when the MC is locked (with the DC value ~4.5 with the MC unlocked, as usual).  This is hard to achieve, but important.  Also, check the MC spot centering.

* With the WFS servo off, but the MC locked and light on the WFS diodes, run the script. 

  6679   Thu May 24 19:39:18 2012 SureshUpdateIOOMC and WFS alignment adjusted

[Yuta, Suresh]

We found that the MC was not locking and that the alignment between PSL and MC was too poor to obtain a TEM00 mode in the MC.   To correct the situation we went through the following steps:

1) We burt restored the MC alignment slider values to their values at 3:07 AM of today

2) We turned off the MC-autolocker and the ASC signal to the coils.   Then aligned the PSL beam into the MC (with the MC servo loop off) to obtain the TEM00 mode.  We had to adjust the zig-zag at the PSL output by quite a bit to maximise MC transmission.

3) We then centered the spot on the MC2 face and centered the transmitted beam on the MC2_TRANS_QPD

4) Next, we centered the beams on the MC_WFS sensors.

5) Turning on the WFS loops after this showed that everything works fine and WFS loops do not accumulate large offsets.

 

 

  10317   Fri Aug 1 01:57:24 2014 KojiSummaryIOOMC auto locker

To make MC auto locker running correctly, mcdown and mcup were revised

I tried it by unlocking MC several times. It seems OK. Let's see how it works.


Nominal gains for locking (to be taken care by mcdown)

C1:IOO-MC_REFL_GAIN
was 16 and is 19 now.

C1:IOO-MC_VCO_GAIN
was 9 and is 9 now too.

C1:PSL-FSS_MGAIN
was missing and now +13

C1:PSL-FSS_FASTGAIN
was +23.5 and is now +20.0

Nominal gains for operation ( to be taken care by mcup.

C1:IOO-MC_REFL_GAIN
was 19 and is 19 now too.

C1:IOO-MC_VCO_GAIN
was 25 and now uses ezcastep (ezcastep C1:IOO-MC_VCO_GAIN=9 +1,16 -s 0.1)

C1:PSL-FSS_MGAIN
C1:PSL-FSS_FASTGAIN

ezcawrite C1:PSL-FSS_MGAIN `ezcaread -n C1:PSL-STAT_FSS_NOM_C_GAIN`
ezcawrite C1:PSL-FSS_FASTGAIN `ezcaread -n C1:PSL-STAT_FSS_NOM_F_GAIN`

 

C1:PSL-STAT_FSS_NOM_C_GAIN`  is +18
C1:PSL-STAT_FSS_NOM_F_GAIN`   is +20

  10319   Fri Aug 1 08:55:34 2014 KojiSummaryIOOMC auto locker

It seems that the MC auto locker and the FSSSlow PID servo survived a night.

PC Drive is still angry occasionally. We want to know what this is.

Attachment 1: MC.png
MC.png
  36   Wed Oct 31 08:38:35 2007 ranaProblem FixedIOOMC autolocker
The MC was having some trouble staying locked yesterday. I tracked this down to some steps in the last
half of the mcup script; not sure exactly which ones.

It was doing something that made the FAST of the PSL go to a rail too fast for the SLOW to fix.
So, I broke the script in half so that the autolocker only runs the first part. We'll need to
fix this before any CM locking can occur.

We also need someone to take a look at the FSS Autolocker; its ill.
  7735   Tue Nov 20 20:37:51 2012 KojiUpdateIOOMC autolocker

Last night I found that the MC autolocker has not been updated since the chamber was closed.
i.e. The low power version had been used.

I logged into op340m and modified crontab via "crontab -e" so that the normal power version is spawned.

  10048   Tue Jun 17 12:04:40 2014 manasaUpdateComputer Scripts / ProgramsMC autolocker NOT running, FB needs some attention

MC autolocker and Ottavia

I assume that the MC was left with a fully functioning autolocker enabled and running on ottavia last night.

But as of this morning, the MC autolocker is NOT running alright. The MC was in an unlocked state and the autolocker has been doing nothing to the servo sliders.  I think this was the state of MC since last night as seen on the stripchart.

Since the autolocker has been left to run on ottavia, I tried to look at the cronlogs to see if it running the autolocker script at all. I looked at the list on ottavia and it has the MCautlocker on it cronjobs list and yet doing nothing.

Later, I did a softreboot on ottavia when I could not ssh into it from rossa or pianosa. ssh to ottavia now works just fine.

I am leaving Ottavia at this and returning to the more important job of fixing the MC. I locked the MC manually and am now working on the alignment.

 

Framebuilder

Also, the CDS FE status screen had red lights blinking as if it required an 'mxstream restart'. I did the same and it did not fix the problem. So I tried to restart fb using the usual 'telnet fb 8087'; but could not restart fb that way.

Attached: FE status screen

Attachment 1: FE_red.png
FE_red.png
  10247   Mon Jul 21 13:58:33 2014 ericqUpdateIOOMC autolocker acting up

The autolocker claimed it was running and blinking, but not doing anything (i.e. lock bit was not updating and no switches or sliders being touched)

After stopping and starting it a number of times, it began working again, through no real changes of my own. I'm a little mystified as to what the problem was... keep an eye out.

  8627   Thu May 23 10:48:42 2013 ManasaUpdateIOOMC autolocker and MCWFS enabled

Some strong seismic noise (not related to any earthquakes - watchdogs are all green) had got the MC unlocked this morning.

I found the MC autolocker and MCWFS disabled. Enabling them locked the MC right away. I don't see any updates in the elog  as to why these were left disabled and hence have left them ON now.

  5689   Tue Oct 18 22:47:09 2011 SureshConfigurationIOOMC autolocker script edited to shutdown and restart WFS loops

Quote:

I found that the MC WFS had large offset control signals going to the MC SUS. Even though the input switch was off, the integrators were holding the offset.

I have disabled the ASCPIT outputs in the MC SUS. Suresh is going to fix the MC autolocker script to gracefully handle the OFF and ON and then test the script before resuming the WFS testing.

MCL data for OAF may be suspect from this morning.

 I have edited (uncommented existing commands)  the following scripts to enable WFS locking to come on when the MC is locked.

1) $scripts$/MC/autolockMCmain40m*

2) $scripts$/MC/mcup

3) $scripts$/MC/mcdown

4) $scripts$/MC/WFS/mcwfson

5) $scripts$/MC/WFS/mcwfsoff.

I have checked that the autolocker script switches off the mcwfs when mc loses lock and then switches it on after re-obtaining lock.

 

  16480   Tue Nov 23 18:02:05 2021 AnchalUpdateIMCMC autolocker shifted to python3 script running in docker

I finished copying over the current autolocker bash script functionality into a python script which runs using a simple configuration yaml file. To run this script, one needs to ssh into optimus and :

controls@optimus|~> cd /opt/rtcds/caltech/c1/Git/40m/scripts/MC
controls@optimus|MC> sudo docker-compose up -d
Creating mc_AL_MC_1 ... done

That's it. To check out running docker processes, one can:

controls@optimus|MC> sudo docker ps

And to shut down this particular script, in the same directory, one can

controls@optimus|MC> sudo docker-compose down
Removing mc_AL_MC_1 ... done

If the docker image requires to be rebuild in future, go to the directory where Dockerfile is present and run:

controls@optimus|MC> sudo docker build -t pyep .

I had to add PyYAML package in the pyepics docker image already present on docker hub, thanks to Andrew.

For now, I have disabled the MCautolocker service on Megatron. To start it back again, one would need to ssh into megatron and do following:

~> sudo systemctl enable MCautolocker
~> sudo systemctl start MCautolocker

Let's see for a day how this new script does. I've left PSL shutter open and autolocker engaged.

To do: Fix the C1:IFO-STATE epics channel definition so that it takes its bits from separate lock status channels instead of scripts writign the whole word arbitrarily.

  7121   Wed Aug 8 18:01:58 2012 JenneUpdateIOOMC autolocker threshold changed

Jan and Manasa are going to elog about their work later, but it involved putting a BS/window/some kind of pick off in front of the MC Trans QPD, so the total light on the MC Trans QPD is now ~16000 rather than ~26000 counts.  I changed the threshold in the MC autolocker to 5000, so now the MC Trans PD must see at least 5000 counts before the autolocker will engage the boosts, WFS, etc.  Actually, this threshold I believe should have been some several thousand value, but when I went in there, it was set to 500 counts, for low power MC mode during a vent.  It had never gotten put back after the vent to some higher, nominal value.

  3352   Tue Aug 3 03:15:06 2010 nancyUpdateIOOMC back to locked mode

I turned the WFS gain to 0.02 back, and the MC is locked, the data for the seismic motion might be meaningful nowforth.

  4660   Sun May 8 16:32:52 2011 valeraUpdateIOOMC beam spot centering

 Kiwamu told me that the CDS matrix notation has changed and the 40m front end code has changed since February. I changed the senseMCdecentering script to reflect that. The other problems were: the "-" sign in ezcastep on ubuntu is not recognized - I used the known workaround of using "+-" instead; the echo command in csh script on ubuntu does not make a new line - but the echo " " does. The script ran on ubuntu with one error message "FATAL: exception not rethrown" but it finished nevertheless. The data appeared ok.  On centos machine the script produced "Segmentation fault'. The matlab script sensemcass.m now calculates the position on the MC mirrors in mm. The attached table shows the MC spot positions in mm:

    feb 26 2011      may 08 2011
MC1 pit   1.6   1.9
MC2 pit   6.4   9.0
MC3 pit   1.4   2.0
MC1 yaw   -1.5   -1.7
MC2 yaw   1.0   0.2
MC3 yaw   -1.3   -1.9

I had to rephase the lockin digital phases by tens of degrees. I don't know why this should happen at ~10 Hz.

 

  4661   Sun May 8 17:29:01 2011 ranaUpdateIOOMC beam spot centering

It seems like the best option would be to make the MCASS just adjust the SUS biases and center the beams on the suspended optics. Is this not possible somehow?

  4659   Sat May 7 18:08:54 2011 valeraUpdateIOOMC beam spot centering script

I tried to run the scripts/senseMCdecentering to check the centering of the MC beam spots on the mirrors. The script (csh) produces a lot of error messages on the control room machines. They are machine dependent combination of "epicsThreadOnce0sd epicsMutexLock failed", "Segmentation fault", "FATAL: exception not rethrown". Most of ezcawrite commands fail but not all(?). After running the mcassUp script couple of times all the dither lines came on. The MCL responses to dither lines look qualitatively similar to what it was in February (plot attached). The overall MCL spectrum looks ~100 times lower, presumably due to the analog gain reallocation.

Before that I realigned the beam into the PMC, recentered the PSL QPDs, and the beam into the MC to bring the MC RFPD_DC from ~3 to ~1.5 VDC then tweaked MC2 to bring the MC RFPD_DC from ~1.5 to ~1 VDC.

The mcass dither lines are off now and the loops are disabled.

Attachment 1: mcditherlines2.pdf
mcditherlines2.pdf
  6715   Wed May 30 15:51:22 2012 yutaUpdateIOOMC beam spot oscillation

[Koji, Suresh, Jenne, Yuta]

Background:
  We noticed that the beam spots on MC mirrors are oscillating in ~ 1 Hz yesterday. It means MC mirrors are actually oscillating. This was observable even if the WFS servo is off.

What we did:
  1. By measuring the spectra of OSEM sensor outputs, we found that MC3 is the one that is oscillating.

  2.  Oscillation at ~ 1 Hz only happened when the local damping using OSEMs are on (see Attachment 1; REF is when the damping is on).

  3.  We found that this oscillation came from insufficiency in phase margin in SUSPOS loop. So, we increased the gain, C1:SUS-MC3_SUSPOS_GAIN, from 95 to 200. It helped a little, but oscillation is still there.

  4.  We measured openloop transferfunctions of SUSPOS, SUSPIT, SUSYAW, SUSSIDE loop, and concluded that diagonalization some how went wrong. The amplitude of the oscillation (peak height in the OSEM spectra) changed by pushing the MC SUS connectors.

Plan:
  - Fix the connectors so that we don't have to push them any more.
  - Redo the diagonalization of the MC suspensions.

Attachment 1: specMC3_onoff_localdamping.pdf
specMC3_onoff_localdamping.pdf
  6718   Wed May 30 19:27:38 2012 yutaUpdateIOOMC beam spot oscillation

[Koji, Yuta]

We found that C1:SUS-MC{1,2,3}_TO_COIL_3_4_GAIN was somehow changed to -1, and feedback signal for SIDE was fedback to LLCOIL, which is apparently not correct.
We checked the snapshots on May 25 and confirmed that it was used to be 0, so we fixed it.
We suspect that it happened during the beam spot measurement, because the measurement changes the TO_COIL matrix gains.

Now, we don't see any MC beam spot oscillation.

Quote:

[Koji, Suresh, Jenne, Yuta]

Background:
  We noticed that the beam spots on MC mirrors are oscillating in ~ 1 Hz yesterday. It means MC mirrors are actually oscillating. This was observable even if the WFS servo is off.

 

ELOG V3.1.3-