40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log, Page 107 of 339  Not logged in ELOG logo
IDup Date Author Type Category Subject
  5337   Fri Sep 2 17:52:16 2011 kiwamuUpdateSUSITMX realigned

The new ITMX was aligned by changing the DC biases.

The resultant DC biases are reasonably small.

C1:SUS-ITMX_PIT_COMM = -0.2909

C1:SUS-ITMX_YAW_COMM = -0.0617

 

The alignment was done by trying to resonate the green light in the X arm cavity.

The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.

I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.

The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.

It needs a free swinging diagnosis.

  5338   Fri Sep 2 17:57:18 2011 kiwamuUpdateSUSRe: ITMY released without opening chambers

It stacked again . We should take a closer look at it.

Quote from #5326

The ITMY mirror was released. The OSEM readouts became healthy.

 

  5339   Sat Sep 3 14:47:50 2011 kiwamuUpdateIOOtriple resonant box : brief estimations about reflections and mode. depths

(RF reflections)

The reflected RF power going back to the RF generation box will be :

    Power at 11MHz =  2 dBm

   Power at 29.5 MHz = 3 dBm

   Power at 55 MHz = 9dBm

Assuming the input power at 11 and 55 MHz are at 27 dBm (40m wiki page). And 15 dBm for 29.5 MHz.

Since there is an RF combiner in between the generation box and the resonant box, it reduces the reflections by an additional factor of 10 dB (#4517)

In the estimation above, the reduction due to the RF combiner was taken into account.

 

(Modulation depths)

Besides the reflection issue, the circuit meets a rough requirement of 200 mrad at 11 and 55 MHz.

For the 29.5 MHz modulation, the depth will be reduced approximately by a factor of 2, which I don't think it's a significant issue.

So the modulation depths should be okay.

Assuming the performance of the resonant circuit remains the same (#2586), the modulation depths will be :

      Mod. depth at 11 MHz =  280 mrad

      Mod. depth at 29.5 MHz = 4 mrad (This is about half of the current modulation depth)

      Mod. depth at 55 MHz = 250 mrad

 

Quote from #5336

What are the reflected RF powers for those frequencies? 
Is the 29.5MHz more problem than the 55MHz, considering the required modulation depth?

 

  5340   Mon Sep 5 21:12:05 2011 DmassUpdateComputer Scripts / Programselog broke, fixed

Restarted elog 9:11PM 9/5/11

  5341   Tue Sep 6 08:05:53 2011 steveUpdateSUSITMX must be touching

Quote:

The new ITMX was aligned by changing the DC biases.

The resultant DC biases are reasonably small.

C1:SUS-ITMX_PIT_COMM = -0.2909

C1:SUS-ITMX_YAW_COMM = -0.0617

 

The alignment was done by trying to resonate the green light in the X arm cavity.

The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.

I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.

The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.

It needs a free swinging diagnosis.

 ITMX OSEMs   UL 1.8V,   UR 1.7V,   LR 0V,   LL 0V,   SD 1.3V  at the same bias setting shown above. May be a lose earth quake tip?or magnet is touching?

Attachment 1: osemITMX.jpg
osemITMX.jpg
  5342   Tue Sep 6 11:21:33 2011 JenneUpdateSUSITMX rehung (Friday)

[Jenne, Katrin, Jamie]

I'm a bad kid, and forgot to elog my Friday morning work...

Bob gave me back ITMX after a 48hour bake at 80C + clean RGA scan Friday morning after coffee and doughnuts.  Katrin helped me put it back in the suspension wire. 

While I was leveling the optic (making sure the scribe lines on each side of the optic are at the same height off the table), Katrin cut some new viton for replacement EQ stops.  The optic was missing one lower earthquake stop (the one that Jamie noticed last week), and somehow one other rubber piece came out of the EQ stop on another lower screw while we were re-suspending the optic.  We put the new stops in, and then checked the balance of the test mass.

The oplev is still the HeNe laser that is leveled to the level optical table in the cleanroom.  The lever arm is ~1.5 meters, and over that distance the reflected beam was pointed "up" in pitch by ~1.5mm, which is less than one beam diameter of the HeNe.  This is well within our ability to correct using the OSEMs.

We then locked the test mass, and installed it in the chamber.  I approximately did the half-voltage centering of the OSEMs, leaving the fine-tuning to Kiwamu for after lunch. 

  5343   Tue Sep 6 11:27:19 2011 JenneUpdateGeneralAfternoon pre-pumpdown todo list

These are the things that I can think of that we need to do before we can close up:

* Take a close look at both ITMs' OSEMs, and ensure that the magnets aren't too close to either plate in the OSEMs.  Both have had funny business over the past week.

* Do a free swinging test on both ITMs.  (ITMY may not need it, if we haven't touched it since the last free swinging test, but it can't hurt to take the data)

* Confirm that POX is exiting the chamber.

* Is there anything else???

 

Our goal is to finish this work by tonight, so that we can close doors and start pumping tomorrow.

  5344   Tue Sep 6 17:43:01 2011 SureshUpdateIOOFree Swing ITMY started

Free swing of ITMY started at

Tue Sep  6 17:41:43 PDT 2011

 

  5345   Tue Sep 6 17:48:57 2011 kiwamuUpdateSUSfree swinging test on ITMY

Tue Sep  6 17:48:02 PDT 2011
999391697

  5346   Tue Sep 6 17:56:12 2011 JenneUpdateSUSfree swinging test on ITMX

Quote:

Tue Sep  6 17:48:02 PDT 2011
999391697

 Kiwamu excited ITMY (which Suresh had already started).  I just kicked ITMX:

Tue Sep  6 17:55:21 PDT 2011
999392136

  5347   Tue Sep 6 17:56:53 2011 JenneUpdateIOOFree Swing ITMY started

Quote:

Free swing of ITMY started at

Tue Sep  6 17:41:43 PDT 2011

 

 I think Kiwamu accidentally restarted this kick at 17:48:02 PDT.

  5348   Tue Sep 6 21:00:48 2011 ZachUpdateelogelog restarted

I restarted the elog with the script as it was not up when I tried to make a post. It was again unresponsive when I went to submit, but this time the script couldn't restart it. The log said it couldn't bind to 8080, which usually happens if the daemon is still running. I pkilled it, then reran the script, and it appears to be working.

  5349   Tue Sep 6 21:33:21 2011 JenneUpdateSUSDiagonalizability of ITMX and ITMY is acceptable

[Rana and Kiwamu on ITMX, Jenne and Suresh on ITMY, Zombie/brains meeting on accepting the matricies]

 

Optic Spectra Matrix "Badness"
ITMX ITMX.png       pit     yaw     pos     side    butt
UL    0.584   0.641   1.396  -0.578   0.558 
UR    0.755  -1.359   0.120  -0.286   0.262 
LR   -1.245  -0.139   0.604  -0.388   0.511 
LL   -1.416   1.861   1.880  -0.681  -2.669 
SD   -0.753   0.492   3.263   1.000  -1.523 
 5.85983
ITMY  ITMY.png           pit     yaw     pos     side    butt
UL    1.000   0.572   1.134  -0.059   0.951  
UR    0.578  -1.428   0.916  -0.032  -1.024  
LR   -1.422  -0.531   0.866  -0.009   1.086  
LL   -1.000   1.469   1.084  -0.036  -0.939  
SD   -0.662   0.822   1.498   1.000   0.265  
4.47727
 

 OSEMs were tweaked.  We have decided that both ITMs are okay in terms of their diagonalization.  ITMY isn't stellar when you look at the spectra, but it's kind of close enough.  Certainly the matrix looks fine.

Aside from checking on POX, I think we're now ready to close up.  Check back later tonight for a final decision announced on the elog.

  5350   Tue Sep 6 22:51:53 2011 ranaSummaryCamerasAll Camera setups a need upgrading

I just tried to adjust the ETMY camera and its not very user friendly = NEEDS FIXING.

* Camera view is upside down.

* Camera lens is contacting the lexan viewport cover; this means the focus cannot be adjusted without misaligning the camera.

* There's no strain relief of the camera cables at the can. Needs a rubber cable grommet too.

* There's a BNC "T" in the cable line.

Probably similar issues with some of the other setups; they've had aluminum foil covers for too long. We'll have a camera committee meeting tomorrow to see how to proceed.

  5351   Wed Sep 7 00:01:23 2011 SureshUpdateIOOITMY chamber ready for heavy doors

[Jenne, Suresh]

We did the following things in the ITMY chamber today:

1) We tried to get the ITMY stuck again by adjusting the coil gains so that it goes into the orientation where it used to get stuck.  We (reassuringly) failed to get it stuck again.  This, as we came to know later, is because kiwamu had rotated the side OSEM such that the optic does not get stuck . However the OSEM beam is at about 30 deg to the vertical and the SD is sensitive to POS motion now resulting in the poorer separation of modes as noted by Jenne earlier (5439)

2) We checked the earthquake stops and repositioned two at the bottom (towards the AR side of the optic)  which we had backed out earlier.

3) We took pics of all the OSEMS.

4) Checked to see if there are any stray beams with an IR card.  There were none.

5) I obtained the max values of the OSEMS by misaligning the optic with the coil offsets.  These values are in good agreement with those on the wiki

OSEM     UL     UR     LR     LL      SD

Max      1.80    1.53   1.68   1.96    2.10

Current  0.97   0.79    0.83   0.97   1.02

 

We can close the heavy doors tomorrow morning.

  5352   Wed Sep 7 00:39:34 2011 ranaUpdateSUSITMX adjustments

(What we did)

* Moved SUS to edge of table for OSEM adjustment.

* Leveled the table in this temporary tower position.

* Rotated all OSEMs to give some seperation between magnets and LED/PD packages.

* Moved the upper OSEM bracket a little bit upward.

* All the OSEM holding set screws were short with flat heads; this is annoying since we would like to use them more like thumbscrews. Steve took the long set-screws out of the old ITMX cage and we swapped them. Need to order ~100 silver-plated socket head spare/replacements.

* Took pictures of OSEMs.

* Moved tower back to old position.

* Releveled the table (added one rectangular weight in the NW corner of the table).

* Find that ITMX OSEMs were a couple 100 micron out of position; we adjusted them in-situ in the final position of the tower, trying not to rotate them. All mean voltages now are within 100 mV of ideal half-light.

* Back/front EQ positions adjusted by the screw method. bottom/top stops adjusted earlier.

* OSEM cables tied down with copper wire.

* Increased the incident power up to 91 mW going into MC to temporarily make the POX beam more visible.

* The POX beam was checked. It was exiting from the chamber and going through about the center of the viewport.

  5353   Wed Sep 7 00:44:51 2011 JenneUpdateSUSFreeswing all

I just started a freeswing all, as a final check before we pump:


Wed Sep  7 00:43:21 PDT 2011
999416616

Wed Sep  7 00:43:32 PDT 2011
WATCHDOGS WILL BE RESET 5 HOURS AFTER THIS TIME
sleeping for 5 hours...

Jamie: Please do a quickie analysis (at least for the ITMs) before helping Steve with the heavy doors.

I closed the PSL shutter.

Both ITM chambers were checked for tools, so there should be nothing left to do but put the heavy doors on, and begin pumping.

  5354   Wed Sep 7 00:47:51 2011 JenneUpdateVACPUMP is a GO!

Steve and Jamie:  After Jamie checks the ITM free swingings, please put on the ITM heavy doors and start the pump!  For real this time!!! Yeah!

  5355   Wed Sep 7 08:14:01 2011 steveUpdateSUSfinal OSEM check

All fine, except ITMX_sensor_UL's  60  counts deep hoop for an hour.

Attachment 1: finalcheck.jpg
finalcheck.jpg
Attachment 2: ITMX10min.jpg
ITMX10min.jpg
Attachment 3: finalsum.png
finalsum.png
  5356   Wed Sep 7 09:21:57 2011 jamieUpdateSUSSUS spectra before close up

Here are all suspension diagonalization spectra before close up. Notes:

  • TMX looks the worst, but I think we can live with it. The large glitch in the UL sensor at around 999423150 (#5355) is worrying. However, it seemed to recover. The spectra below were taken from data before the glitch.
  • ITMY has a lot of imaginary components. We previously found that this was due to a problem with one of it's whitening filters (#5288). I assume we're seeing the same issue here.
  • SRM needs a little more data to be able to distinguish the POS and SIDE peaks, but otherwise it looks ok.
ITMX ITMX.png        pit     yaw     pos     side    butt
UL    0.355   0.539   0.976  -0.500   0.182 
UR    0.833  -1.406  -0.307  -0.118   0.537 
LR   -1.167   0.055   0.717  -0.445   0.286 
LL   -1.645   2.000   2.000  -0.828  -2.995 
SD   -0.747   0.828   2.483   1.000  -1.637 
8.01148
ITMY  ITMY.png        pit     yaw     pos     side    butt
UL    1.003   0.577   1.142  -0.038   0.954  
UR    0.582  -1.423   0.931  -0.013  -1.031  
LR   -1.418  -0.545   0.858   0.008   1.081  
LL   -0.997   1.455   1.069  -0.017  -0.934  
SD   -0.638   0.797   1.246   1.000   0.264
 4.46659
BS  BS.png        pit     yaw     pos     side    butt
UL    1.612   0.656   0.406   0.277   1.031  
UR    0.176  -1.344   1.683  -0.058  -0.931  
LR   -1.824  -0.187   1.594  -0.086   0.951  
LL   -0.388   1.813   0.317   0.249  -1.087  
SD    0.740   0.301  -3.354   1.000   0.035 
 5.49597
PRM  PRM.png        pit     yaw     pos     side    butt
UL    0.546   1.436   1.862  -0.345   0.866  
UR    1.350  -0.564   0.551  -0.055  -0.878  
LR   -0.650  -0.977   0.138   0.023   0.858  
LL   -1.454   1.023   1.449  -0.268  -1.398  
SD    0.634  -0.620  -0.729   1.000   0.611
 5.78216
SRM      
ETMX ETMX.png        pit     yaw     pos     side    butt
UL    0.863   1.559   1.572   0.004   1.029  
UR    0.127  -0.441   1.869   0.480  -1.162  
LR   -1.873  -0.440   0.428   0.493   0.939  
LL   -1.137   1.560   0.131   0.017  -0.871  
SD    1.838   3.447  -0.864   1.000  -0.135 
 5.5259
ETMY  ETMY.png        pit     yaw     pos     side    butt
UL   -0.337   1.275   1.464  -0.024   0.929  
UR    1.014  -0.725   1.414  -0.055  -1.102  
LR   -0.649  -1.363   0.536  -0.039   0.750  
LL   -2.000   0.637   0.586  -0.007  -1.220  
SD    0.057  -0.016   1.202   1.000   0.142 
 4.22572
MC1  MC1.png        pit     yaw     pos     side    butt
UL    0.858   0.974   0.128   0.053  -0.000  
UR    0.184  -0.763   0.911   0.018   0.001  
LR   -1.816  -2.000   1.872   0.002   3.999  
LL   -1.142  -0.263   1.089   0.037   0.001  
SD    0.040   0.036  -0.216   1.000  -0.002 
 5.36332
MC2  MC2.png        pit     yaw     pos     side    butt
UL    1.047   0.764   1.028   0.124   0.948  
UR    0.644  -1.236   1.092  -0.088  -0.949  
LR   -1.356  -0.680   0.972  -0.096   1.007  
LL   -0.953   1.320   0.908   0.117  -1.095  
SD   -0.092  -0.145  -0.787   1.000  -0.065 
 4.029
MC3  MC3.png        pit     yaw     pos     side    butt
UL    1.599   0.343   1.148   0.168   1.101  
UR    0.031  -1.647   1.139   0.202  -1.010  
LR   -1.969   0.010   0.852   0.111   0.893  
LL   -0.401   2.000   0.861   0.077  -0.995  
SD   -0.414   0.392  -1.677   1.000   0.018 
3.61734

 

  5357   Wed Sep 7 12:03:49 2011 steveUpdateVACPump down has started

Jamie and Steve

We closed ITMX and ITMY chambers and started pumping around 11am

What we did before:

1, turned off AC power  to PZT Jena HV ps

2, checked jam nut positions

3, cheched  single o-ring shims

4, closed psl out shutter

  5358   Wed Sep 7 13:28:25 2011 steveSummaryCamerasAll Camera setups a need upgrading

Quote:

I just tried to adjust the ETMY camera and its not very user friendly = NEEDS FIXING.

* Camera view is upside down.

* Camera lens is contacting the lexan viewport cover; this means the focus cannot be adjusted without misaligning the camera.

* There's no strain relief of the camera cables at the can. Needs a rubber cable grommet too.

* There's a BNC "T" in the cable line.

Probably similar issues with some of the other setups; they've had aluminum foil covers for too long. We'll have a camera committee meeting tomorrow to see how to proceed.

 ITMY has been upgraded  here I have the new lenses on hand to do the others when it fit into the schedule.

  5359   Wed Sep 7 16:21:35 2011 kiwamuUpdateLSCarm loss measurement : resluts

Here are the results of the arm loss measurements, which I have done before the vent.

I ran the existing matlab script, called 'armLoss.m', to estimate the loss. The script resides in /scripts/LSC.


(Y arm)

 Round trip loss =  154.668624 +/- 11.343204 ppm

Yarmloss.png

The figure above is a time series of the measurement.

In the lower plot the power in the ASDC_PD are plotted. The green dotted-curve is the power when the Y arm is unlocked.

The blue dotted-curve is the one when the Y arm is locked.

In the upper plot the estimated loss from each combination of locked/unlocked power are plotted.

 


(X arm)

Round trip loss = ????? 50 ppm ?????

The obtained time series looked wired because difference in the ASDC power when the arm was locked/unlocked were small.

This small difference results in such a small loss.

To see what was going on I will look at the trend data.

Xarmloss.png

Quote from #5077

I did the measurement of the arm loss on both X and Y arm by running the armLoss script.

The results will be posted later.

 

  5360   Wed Sep 7 17:28:41 2011 kiwamuUpdateLSCX arm loss measurement : not good

The measurement itself wasn't good.

I looked at the full 2 kHz data which was taken during the time when I was running the arm loss script on the X arm.

The plot below shows the raw data. The X arm was locked and unlocked sequentially several times.

The ASDC power didn't show a significant difference between the state where it is locked and unlocked.

I am not sure why, but It could be because of a misalginment or some kind of mode-mismatching, which can decrease the coupling efficiency of light going into the cavity.

 

Xarmlossmeasurement.png

 

(some notes)

The raw data were analyzed.

I split the ASDC data into two data, (1) low power state, when the cavity is locked (2) high power state, when the cavity is unlocked.

Then each state was averaged to estimate the averaged ASDC power in each case.

The number I obtained are :

    ASDC when X arm was locked = 54.77755 cnts

    ASDC when X arm was unlocked = 55.45830 cnts

Those numbers correspond to a round trip loss of  78.780778 ppm, which sounds too small for me.

Quote from #5359

To see what was going on I will look at the trend data.
 

 

  5361   Wed Sep 7 18:19:37 2011 steveHowToVACstop pump down for overnight

Quote:

Jamie and Steve

We closed ITMX and ITMY chambers and started pumping around 11am

What we did before:

1, turned off AC power  to PZT Jena HV ps

2, checked jam nut positions

3, cheched  single o-ring shims

4, closed psl out shutter

 We are at 30 Torr of 7 hours of pumping with 2 roughing pumps.

Kiwamu will take over the rest of the roughing today. He will keep an eye on  the pumping speed to be  ~1-2 Torr/min  and open up the manual RV1 valve if needed.

The present status is #3023 of  "chamber open to vacuum open" mode and waiting the P1 pressure to drop to 500 mTorr

He will do the following to stop pumping at P1 = 500 mTorr

1, close V3

2, close RV1 with torque wheel

3, turn off PR1 & 3

4, disconnect metal hose between RV1 and PR3

 I will start the Maglev tomorrow morning.

  5362   Wed Sep 7 20:44:11 2011 SureshUpdateelogrestarted

Elog crashed / dormant for long time.  A look at the log file indicated that it was busy generating png thumbnails for pdf files.

Restarted at Wed Sep  7 20:41:13 PDT 2011

 

  5363   Wed Sep 7 21:45:16 2011 kiwamuUpdateVACpump stopped. Pressure is at 450 mtorr

I stopped puming at 9:30 PM and the pressure in P1 is at 450 mtorr.

I followed exactly he procedure that Steve noted on his elog entry.

Here is a plot of the histroy of our pumping today.

vacuum.png

Quote from #5361

 1, close V3

2, close RV1 with torque wheel

3, turn off PR1 & 3

4, disconnect metal hose between RV1 and PR3

 I will start the Maglev tomorrow morning.

  5364   Wed Sep 7 22:17:04 2011 ranaUpdateIOORF Amp for EOM on PSL Table

After Steve pointed out the 'deep hoop' issue, we decided to examine putting an RF Amp on the PSL table, between the RF combiner and the triple resonant box.

This will reduce the chances of standing waves in the cables and reduce the radiation induced pick-up in the RF PD and Demod electronics.

We would like to send ~10 dBm from the distribution box to the combiner. We also want to able to get as much as ~33 dBm of drive at 11 and 55 MHz. So the amp should have a gain of ~20-30 dB and an operating range of 10-100 MHz.

Also desirable are low distortion (high IP3) and good reverse isolation ( > 40 dB).

Some possibilities so far (please add your RF Google Results here):

1) Mini-Circuits ZHL-1-2W-S:  G = +32 dB, Max Out = +33 dBm, NF = 6 dB, Directivity = 25 dB

2) Mini-Circuits TIA-1000-1R8:  G=+40 dB, Max Out = +36 dBm, NF = 15 dB   (AC Powered, Inst. Amp), Directivity = 58 dB.

3) Mini-Circuits ZHL-2-8: G = +27dB, Max out = +29 dBm, NF = 6dB, Directivity = 32 dB

4) RFbay MPA-10-40: G = +40dB, Max Out = + 30 dBm, NF = 3.3 dB, Rev Iso = 23 dB

5) No proper stuff from Teledyne Couger

 

  5365   Thu Sep 8 10:50:44 2011 steveUpdateVACpumpdown #71 comleted

Vacuum status:  " vacuum normal"   CC1 pressure 5e-5 Torr

Slow roughing through butterfly valve took 11 hours at 1-2 Torr/min speed.  We had a leak at the metal hose connecting o-ring  that became visible  at 200 Torr.

The vacuum envelope pressure rose to 500 mTorr from 450 mTorr  This is 50 mTorr leak plus outgassing over 11 hrs  over night stop =  5  mTorr /  hr

Atm2, Maglev pumpdown details. P2 and P3  are in the foreline of the Maglev. The pressure peaks at 4 Torr beacause the 3 drypumps have  little pumpimg speed at this range.

            External fan is turned on during this one hour period to prevent  Maglev turbo from overheating.

            Same things are  happenning with the two small TP2 and TP3 pumps under load. Their foreline pressure peak at 1 Torr.  They slow down to 45 K RPM from 50K RPM  and warm up to 36-39 C

Precondition: 36 days at atm

Attachment 1: pd#71.jpg
pd#71.jpg
Attachment 2: maglevpd.jpg
maglevpd.jpg
  5366   Thu Sep 8 13:20:07 2011 steveUpdatePEMvac envelope at atm for 36 days

We tried not to open chambers above 10,000 particles of 0.5 micron cf/min

New items going in:                       2 rasor beam traps, 5 badly oxidized old silver plated  setscrew with spring loaded tips......to be replaced in the future, viton tips for eq screws....some are lose, gold plated allen wrench installed at ITMX bottom, reglued magnet on ITMX

Bad hardware things found:          nylon ball "locking elements" on OSEM locking set screws with screwdriver  slot, lose  1064 nm filter on OSEM pd

Attachment 1: vent70.jpg
vent70.jpg
  5367   Thu Sep 8 20:13:24 2011 kiwamuUpdateIOOMC is back to full power

[Suresh / Kiwamu]

 The attenuator was removed and now the MC is happily locked with the full power of 1.2 W.

 

(what we did)

 + replaced the perfect reflector, which was before the MCREFL_PD, by a 10% beam splitter like it used to be.

 + removed the attenuator (combination of HWP and PBS).

 + realigned the beam path on the AP table, including the MCREFL path and WFS path.

 + made the aperture of the MC2F camera narrower in order to avoid a saturation.

 + aligned the MC suspensions so that it resonates with the TEM00 mode.

 + put a ND filter on the AS camera

 

(notes)

C1:IOO-MC_RFPD_DCMON = 0.98 (locked)

C1:IOO-MC_TRANS_SUM = 17500 (locekd)

 

(next things to do)

 + measurement of the spot positions on each MC mirror.

 + centering of the beam spot by steering the input mirrors on the PSL table

  5368   Fri Sep 9 11:59:58 2011 kiwamuUpdateIOOPZT1 doesn't work

Last night I noticed that PZT1 didn't work properly

I am not sure what is going on. Today I will try localizing the cause of the problem.

As far as I remember it was perfectly working at the time just after we readjusted the OSEMs on MC1 and MC3 (Aug 23th)

 

The symptoms are :

  + No response to both pitch and yaw control from EPICS (i.e. C1:LSC-PZT1_X and C1:LSC-PZT1_Y)

  + When a big value (-3 or so) from EPICS was applied, the PZT1 mirror suddenly jumped.

     However it turned out it just corresponded to a state where OOR (Out Of Range) LED lights up.

 

I did some brief checks :

  + checked the voltage going into the HV amplifiers' "MOD" input. Those are the voltage coming out from DACs and controlled from EPICS.

   --> looked healthy. They went from -10 to 10 V as expected (although the HV amp takes up to only +/-5V).

  + swapped the ''MOD" input cables such that C1:LSC-PZT1 controls the PZT2 HV and vice versa.

    --> The PZT2 mirror was still controlable, but the PZT1 mirror still didn't move. So the DAC and EPICS are innocent.

  + swapped the D-dub cables, which are directly going into the feedthroughs, such that the PZT1 HV drives the PZT2 mirrors and vice versa.

    --> the PZT2 mirror became unable to be controlled. For the PZT1 mirror, only PITCH worked smoothly.


  5369   Fri Sep 9 13:29:09 2011 kiwamuUpdateIOOa history of PZT mirror

Something happened about 8 years ago.

Old iLog entry by AJW (2003/Sep/8)

Old iLog entry by AJW (2003/Sep/9)

Quote:

Last night I noticed that PZT1 didn't work properly

 

  5370   Fri Sep 9 14:55:03 2011 kiwamuUpdateSUSOSEM pictures on ITMs

The OSEM pictures taken in Sep/6 have been uploaded to Picasa.

https://picasaweb.google.com/foteee

  5371   Fri Sep 9 16:16:59 2011 kiwamuUpdateIOOspot positions on MC mirrors (in-vac)

The spot positions on the MC mirrors were measured in the vacuum condition.

The obtained spot positions are quite bad and roughly at 2-3 mm level. We have to realign the beam axis and the MC mirrors.

 

    Feb 26 2011      May 08 2011 Aug 2 2011  Aug 10 2011 (in air) Aug 14 2011 (in air)

Aug 23 2011 (in air)

[NEW]  Sep 9 2011
MC1 pit [mm]   1.6   1.9  1.93 -0.858 -0.2 0.1354  -1.55
MC2 pit [mm]   6.4   9.0 9.03 -0.844 -0.8 -0.2522  -2.28
MC3 pit [mm]   1.4   2.0 2.01 -1.03 -0.1 -0.1383  -1.8
MC1 yaw [mm]   -1.5   -1.7 -1.72 -0.847 -1.1 -1.0893  -0.02
MC2 yaw [mm]   1.0   0.2 0.178 0.582 0.6 0.7122  3.52
MC3 yaw [mm]   -1.3   -1.9 -1.87 -1.06 -1.1 -1.5587  -2.145

 

  5372   Fri Sep 9 19:15:17 2011 ranaUpdateIOORF Amp for EOM on PSL Table

Quote:

After Steve pointed out the 'deep hoop' issue, we decided to examine putting an RF Amp on the PSL table, between the RF combiner and the triple resonant box.

5) No proper stuff from Teledyne Couger

 

By looking at what Daniel used in the low noise EOM Driver for aLIGO, we found the A2CP2596 from Cougar.

G = +24 dB, NF = 5 dB, Max Out = +37 dBm. It comes in a 2-stage SMA connector package. I've asked Steve to order 2 of them with the appropriate heatsinks.

  5373   Fri Sep 9 20:52:59 2011 kiwamuUpdateIOOspot positions on MC mirrors (in-vac)

The spot positions on the MC mirrors were readjusted.

All the amount of the off-center became smaller than 2 mm, which meet requirements of the beam clearance on the Faraday.

 

    Feb 26 2011      May 08 2011 Aug 2 2011  Aug 10 2011 (in air) Aug 14 2011 (in air)

Aug 23 2011 (in air)

 Sep 9 2011 [NEW] Sep 9 2011
MC1 pit [mm]   1.6   1.9  1.93 -0.858 -0.2 0.1354  -1.55  0.22
MC2 pit [mm]   6.4   9.0 9.03 -0.844 -0.8 -0.2522  -2.28  -0.34
MC3 pit [mm]   1.4   2.0 2.01 -1.03 -0.1 -0.1383  -1.8 -0.21
MC1 yaw [mm]   -1.5   -1.7 -1.72 -0.847 -1.1 -1.0893  -0.02 -1.15
MC2 yaw [mm]   1.0   0.2 0.178 0.582 0.6 0.7122  3.52 0.07
MC3 yaw [mm]   -1.3   -1.9 -1.87 -1.06 -1.1 -1.5587  -2.145 -1.07

 

 In order to improve the MC1-YAW and MC3-YAW spot positions, the angle of the incident beam has to be shifted by approximately 1/100 rad.

However it turned out to be very difficult to introduce such amount of angle only with the steering mirrors on the PSL table since we have to keep the same translation while changing the angle.

 

Quote from #5371

The obtained spot positions are quite bad and roughly at 2-3 mm level. We have to realign the beam axis and the MC mirrors.

 

  5374   Sat Sep 10 01:36:15 2011 kiwamuUpdateASCinterferometer coarsely aligned

The interferometer was coarsely aligned.

Now spatially overwrapped DRMI and FP arm fringes are visible on the AS camera although the incident beam alignment was done only with PZT2.

All the DC biases were saved so that we can go back to this condition any time.

 

/***** some health checks *******/

 [FINE] IPPOS : it looks okay but the spot on the QPD is a little bit too low by a few mm.

 [NOT GOOD] IPANG : maybe hitting a post or something because the spot is vertically split into two. The spot is too low.

 [FINE] POX/POY/POP : they all are coming out. POP is visible with an IR viewer.

 [FINE] REFL :  no clipping but the beam looks a little bit too low relative to the CCD camera.

 [FINE] AS : no clipping and the spot position on the AS camera looks fine.

 [FINE] Green beams : both X and Y beams are successfully landing onto the PST table without no clipping.

 [FINE] Suspensions : all of them are reasonably quiet without the oplevs, which is good.

  5375   Sat Sep 10 02:28:45 2011 kiwamuUpdateSUSfree swinging test in vacuum condition

All the optcs were excited

Sat Sep 10 02:14:11 PDT 2011
999681266

 

  5376   Sat Sep 10 11:07:37 2011 ranaHowToSUSOptical Lever Servo Tuning thoughts

Now that we are in a moderately stable condition, its time to design the optical lever feedback transfer functions. We should think carefully about how to do this optimally.

In the past, the feedback shape was velocity damping from 0-10 Hz, with some additional resonant gain around the pendulum and stack modes. There were some low pass filters above ~30 Hz. These were all hand tuned.

I propose that we should look into designing optimal feedback loops for the oplevs. In principle, we can do this by defining some optimal feedback cost function and then calculate the poles/zeros in matlab.

How to define the cost function (? please add more notes to this entry):

1) The ERROR signal should be reduced. We need to define a weight function for the ERROR signal: C_1(f) = W_1(f) * (ERR(f)^2)

2) The OL QPDs have a finite sensing noise, so there is no sense in suppressing the signal below this level. Need to determine what the sensing noise is.

3) The feedback signal at high frequencies (30 Hz < f < 300 Hz) should be low passed to prevent adding noise to the interferometer via the A2L coupling. It also doesn't help to reduce this below the level of the seismic noise. The cost function on the feedback should be weighted apprpriately given knowledge about the sensing noise of the OL, the seismic noise (including stack), and the interferometer noise (PRC, SRC, MICH, DARM).

4) The servo should be stable: even if there is a negligible effect on the ERROR signal, we would not want to have more than 10 dB of gain peaking around the UGFs.

5) The OL QPDs are dominated by drift of the stack, laser, etc. at some low frequencies. We should make sure the low frequency feedback is high passed appropriately.

6) Minimize transmitted power rms in single arm lock etc.

  5377   Sat Sep 10 14:55:28 2011 KeikoUpdateLSC3f demodulation board check

 To check the demodulation boards for REFL33 and REFL165, a long cable from ETMY (SUS-ETMY-SDCOIL-EXT monitor) is pulled to the rack on Y side.

(1) A filter just after the RF input and (2) transfer function from the RF input to the demodulated signal will be checked for the two 3f demod boards to confirm that they are appropriate for 33 and 165 MHz.

  5378   Sat Sep 10 16:10:42 2011 KeikoUpdateLSC3f demodulation board check

There is a LP filter just after the RF input of an demodulation board (its schematic can be found as D990511-00-C on DCC). I have checked if the 3f freq, 33MHz, can pass  this filter. The filter TF from the RF input to RF monitor (the filter is between the input and monitor) on REFL33 demo-board was measured as shown in Fig. 1. At 33MHz, the magnitude is still flat and OK, but the phase is quite steep. I am going to consider if it is ok for the PDH method or not.

REFL33-input-filter.png

 Fig. 1 Transfer function from the RF input to RF monitor on the REFL33 demodulation board. At 33MHz, a very steep phase is applied on the input signal.

Quote:

 To check the demodulation boards for REFL33 and REFL165, a long cable from ETMY (SUS-ETMY-SDCOIL-EXT monitor) is pulled to the rack on Y side.

(1) A filter just after the RF input and (2) transfer function from the RF input to the demodulated signal will be checked for the two 3f demod boards to confirm that they are appropriate for 33 and 165 MHz.

 

  5379   Sat Sep 10 18:52:45 2011 ranaUpdateComputersconlog getting filled up

One of the reasons that conlog seems so slow lately is that its been writing 100's of MB of .log files every day since early summer. It looks like the people who have been working on the mdl builds have not been properly adjusting the conlog channel lists. When this is not done conlog just gets filled up with non-control channels like OUT, OUTPUT, OUTMON, etc.

Peter Shawhan has supplied us with many scripts in the conlog directory to clean up these bloated files and fix the channel list.

  5380   Sat Sep 10 18:57:52 2011 KeikoUpdateLSC3f demodulation board check

The phase delay due to the RF input filter on the demodulation board will not bother the resulting PDH signals.

I quickly calculated the below question (see the blue sentence in the quote below). I applied an arbitrary phase delay (theta) due to the filter I measured, on the detected RF signal by the photo detector. Then the filtered RF signal is multiplied by cos(omega_m) then filter the higher (2 omega_m) freqency as the usual mixing operation for the PDH signal. As a result, the I signal is delayed by cos(theta) and the Q signal is delayed by sin(theta). Therefore the resulting signals and its orthogonalitity is kept ok. From the sideband point of view, theta is applied on both upper and lower and seems to make the unbalance, however, as it is like a fixed phase offset on both SBs at the modulation frequency, the resulting signals is just multiplied by cos or sin theta for I and Q, respectively. It won't make any strange effect (it is difficult to explain by sentence not using equations!).

Quote:

There is a LP filter just after the RF input of an demodulation board (its schematic can be found as D990511-00-C on DCC). I have checked if the 3f freq, 33MHz, can pass  this filter. The filter TF from the RF input to RF monitor (the filter is between the input and monitor) on REFL33 demo-board was measured as shown in Fig. 1. At 33MHz, the magnitude is still flat and OK, but the phase is quite steep. I am going to consider if it is ok for the PDH method or not.

 Fig. 1 Transfer function from the RF input to RF monitor on the REFL33 demodulation board. At 33MHz, a very steep phase is applied on the input signal.

Quote:

 To check the demodulation boards for REFL33 and REFL165, a long cable from ETMY (SUS-ETMY-SDCOIL-EXT monitor) is pulled to the rack on Y side.

(1) A filter just after the RF input and (2) transfer function from the RF input to the demodulated signal will be checked for the two 3f demod boards to confirm that they are appropriate for 33 and 165 MHz.

 

 

  5381   Sat Sep 10 19:03:57 2011 ranaUpdateLSCY Arm work

I lined up the Y Arm for locking and then centered the oplevs for ETMY and ITMY.

* The ITMY OL has still got the old style laser. Steve, pleaes swap this one for a HeNe. Also the optical layout seems strange: there are two copies of the laser beam going into the chamber (??). Also, the QPD transimpedance needs to be increase by a factor of ~10. We're only getting ~500 counts per quadrant. Its worth it for someone to re-examine the whole ITMY OL beam layout.

* The ETMY OL beam was coming out but clipping on the mount for the ETMY OL HeNe. This indicates a failure on our part to do the ETMY closeout alignment properly. In fact, I get the feeling from looking around that we overlooked aligning the OL and IPPOS/ANG beams this time. If we're unlucky this could cause us to vent again. I undid part of the laser mount and changed the height on the receiving mirror to get the beam back onto the QPD.

I noticed that there is significant green light now getting into some of the IR PDs; beacuse of this there are weird offsets in the TRY QPD and perhaps elsewhere. We had better purchase some filters to tape over the front of the sensitive IR sensors to prevent the couplling from the green laser.

* There is a beam on IPPOS, but its too big for the detector (this has always been the case). We need to put a 2" lens with a weak focusing power on this path so as to halve the beam size on the detector. Right now its clipping and misleading. There is also a 0.9V offset on the SUM signal. I'm not sure if this readout is working at all.

* I couldn't find any beam on IPANG at all. Not sure what's changed since Kiwamu saw it.

  5382   Sat Sep 10 19:45:29 2011 JenneUpdateLSCY Arm work

Quote:

 * ITMY OL: Also the optical layout seems strange: there are two copies of the laser beam going into the chamber (??).

* The ETMY OL beam was coming out but clipping on the mount for the ETMY OL HeNe. This indicates a failure on our part to do the ETMY closeout alignment properly.

 The 2nd beam from this laser is for the SRM's OpLev, so that shouldn't be changed.

For better or worse, we didn't do anything to the ETM OpLevs, because they don't have any in-vac steering optics.  We did however go through and check on all the corner OpLevs.

  5383   Sat Sep 10 20:30:01 2011 ranaUpdateIOOMC trans re-aligned / MC2 shifted mysteriously / MC2 re-aligned

MCdecenter.png

I re-aligned the beam onto the MC TRANS QPD since Kiwamu had centered the spots on the mirrors. However, I then inspected the MC2F camera. After coming back into the control room I noticed that the MC transmission had gone down by 50% and that the MC2 OSEMs showed a large step. My guess is that somehow the opening and closing of the can shifted the suspension. So I adjusted the MC2 alignment biases to recover the transmitted power (its now ~50000 instead of the ~33000 from Friday).

  5384   Sun Sep 11 15:19:39 2011 kiwamuUpdateLSCphase delay in RF signals

A comment :

Since the LSC RFPD have a long cable of more than 6 m, which rotates a 33 MHz signal by more than 360 deg, so the delay has always existed in everywhere.

The circuit you measured is a part of the delay existing in the LSC system, but of course it's not a problem as you said.

In principle a delay changes only the demodulation phase. That's how we treat them.

RA: Actually, the issue is not the delay, but instead the dispersion. Is there a problem if we have too much dispersion from the RF filter?

 

  5385   Sun Sep 11 22:36:32 2011 KeikoUpdateLSC3f demodulation board check

Filters at the RF inputs of REFL33 and REFL165 demodulation boards were measured again. The filters will be totally fine for 33MHz and 165MHz.

Last time I forgot to calibrate the cable lengths, therefore the phase delay of the measurement included the cable lengths. This time the measurements were done for REFL33 and REFL165 demod board with calibration. As the cable lengths were calibrated, the shown plots (Fig.1 and Fig.2) do not include the phase delay dues to measurement cables. Please note that the x-axis is in linear. The phase delays of both boards seems to be not too steep (it will not affect anyway, as Kiwamu pointed out in his comment on the previous post). You can see that the two filters do not filter 33MHz and 165MHz component out.

REFL33.png

Fig.1 A response of a filter which is placed just after the RF input of the demodulation board for REFL33. X-axis is shown in linear (~50MHz).

REFL165.png

Fig.2 A response of a filter which is placed just after the RF input of the demodulation board for REFL165.

 

Quote:

There is a LP filter just after the RF input of an demodulation board (its schematic can be found as D990511-00-C on DCC). I have checked if the 3f freq, 33MHz, can pass  this filter. The filter TF from the RF input to RF monitor (the filter is between the input and monitor) on REFL33 demo-board was measured as shown in Fig. 1. At 33MHz, the magnitude is still flat and OK, but the phase is quite steep. I am going to consider if it is ok for the PDH method or not.

REFL33-input-filter.png

 Fig. 1 Transfer function from the RF input to RF monitor on the REFL33 demodulation board. At 33MHz, a very steep phase is applied on the input signal.

Quote:

 To check the demodulation boards for REFL33 and REFL165, a long cable from ETMY (SUS-ETMY-SDCOIL-EXT monitor) is pulled to the rack on Y side.

(1) A filter just after the RF input and (2) transfer function from the RF input to the demodulated signal will be checked for the two 3f demod boards to confirm that they are appropriate for 33 and 165 MHz.

 

 

  5386   Mon Sep 12 13:24:07 2011 KeikoUpdateLSC3f demodulation board check

I also quickly checked the orthogonality of the demodulation board for REFL33 and REFL165 using function generators and oscilloscope. I checked the frequencies at 1,10,100,1K,10KHz of the demodulated signals. They are fine and ready for 3f signal extraction.

ELOG V3.1.3-