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ID Date Author Type Categoryup 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.

 

  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?

  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. 

  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

  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.

  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.

  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.

  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

 

  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

  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.

  5403   Wed Sep 14 07:51:20 2011 steveUpdateSUSPRM damping restored

The PRM damping was restored at side sensor var 1050

  5409   Wed Sep 14 20:30:36 2011 ranaUpdateSUSSome screens are still bad

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

Untitled.png

  5411   Wed Sep 14 22:07:41 2011 ranaUpdateSUSITM Oplevs are broken

I went to see what was wrong with the ITMs and found that people have been working on them and have left them in a broken state with no elog entry.

This is sad and unacceptable.

Whoever is working on these should post into the elog what the Oplev layout plan is, have someone check it, and ONLY THEN get to work on it.

The layout as it looks tonight is too complicated. With too many optics we will not have a low noise optical lever setup. The new layout should use a bare minimum number of optics and only use very stable mounts.

mm.jpg

  5415   Thu Sep 15 07:28:08 2011 steveUpdateSUSPRM damping restored

Quote:

The PRM damping was restored at side sensor var 1050

 The PRM sus damping restored.

  5417   Thu Sep 15 15:11:38 2011 kiwamuUpdateSUSf2a filters on BS and PRM

The f2a filters were newly designed and installed on BS and PRM.

So the lock of PRMI will be more stable .

Once the SRM oplev project settles down, I will adjust the f2a filters on SRM too.

  5418   Thu Sep 15 16:45:59 2011 PaulUpdateSUSITMY and SRM Oplev status

Today I worked on getting the ITMY and SRM oplevs back in working order. I aligned the SRM path back onto the QPD. I put excitations on the ITMY and SRM in pitch and yaw and observed the beam at the QPDs to check for clipping. They looked clean from clipping.

 
Measurements of the beam power at various points:
 
Straight after the laser - 7.54mW
After the BS in the SRM path - 1.59mW
After the BS in the ITMY path - 3.24mW
Incident on the SRM QPD - 0.03mW
Incident on the ITMY QPD - 0.25mW
 
Counts registered from the QPD sum channels:
 
SRM QPD SUM dark count - 1140
SRM QPD SUM bright count - 3250
 
ITMY QPD SUM dark count - 150
ITMY QDP SUM bright count - 12680
 
The power incident on the SRM QPD seems very low with respect to the ITMY QPD. Is the SRM mirror coating not very reflective for the He-Ne laser?There are some back reflections from lenses, which we should be careful of to avoid scattering.
  5419   Thu Sep 15 17:00:10 2011 Paul and SteveUpdateSUSNew ITMY and SRM oplev plan

 We have made a new plan for the ITMY and SRM oplev optical path which uses as few optics as possible. This should help to reduce coupling from vibrations of optics in the oplev path back into the GW channel. To get enough room for the turning mirror into the SRM it might be necessary to move the POY optics a bit nearer to the tank. 

  5421   Thu Sep 15 18:12:21 2011 JenneUpdateSUSfree swinging test in vacuum condition

Quote:

All the optcs were excited

Sat Sep 10 02:14:11 PDT 2011
999681266

 

 

Optic The Plot Input Matrix BADness
ITMX  ITMX.png       pit     yaw     pos     side    butt
UL    0.601   0.680   1.260  -1.009   0.223 
UR    0.769  -1.254  -0.175  -0.179   0.581 
LR   -1.231   0.065   0.566  -0.480   0.252 
LL   -1.399   2.000   2.000  -1.310  -2.944 
SD   -0.580   0.868   2.451   1.000  -1.597 

 
7.95029
ITMY  ITMY.png       pit     yaw     pos     side    butt
UL    1.067   0.485   1.145  -0.195   0.929 
UR    0.548  -1.515   0.949  -0.142  -1.059 
LR   -1.452  -0.478   0.855  -0.101   1.051 
LL   -0.933   1.522   1.051  -0.153  -0.962 
SD   -0.530   0.903   2.115   1.000   0.142 
3.93939
ETMX ETMX.png       pit     yaw     pos     side    butt
UL    0.842   1.547   1.588  -0.018   1.026 
UR    0.126  -0.453   1.843   0.499  -1.173 
LR   -1.874  -0.428   0.412   0.511   0.934 
LL   -1.158   1.572   0.157  -0.006  -0.867 
SD    1.834   3.513  -0.763   1.000  -0.133
5.39825
ETMY ETMY.png       pit     yaw     pos     side    butt
UL   -0.344   1.280   1.425  -0.024   0.903 
UR    1.038  -0.720   1.484  -0.056  -1.161 
LR   -0.618  -1.445   0.575  -0.040   0.753 
LL   -2.000   0.555   0.516  -0.007  -1.184 
SD   -0.047  -0.038   0.986   1.000   0.083 
4.15747
BS  BS.png       pit     yaw     pos     side    butt
UL    1.549   0.655   0.393   0.263   0.997 
UR    0.192  -1.345   1.701  -0.063  -0.949 
LR   -1.808  -0.206   1.607  -0.085   0.952 
LL   -0.451   1.794   0.299   0.241  -1.101 
SD    0.724   0.293  -3.454   1.000   0.037 
5.66432
PRM  PRM.png       pit     yaw     pos     side    butt
UL    0.697   1.427   1.782  -0.337   0.934 
UR    1.294  -0.573   0.660  -0.068  -0.943 
LR   -0.706  -1.027   0.218   0.016   0.867 
LL   -1.303   0.973   1.340  -0.254  -1.257 
SD    0.369  -0.448  -0.496   1.000   0.456 
5.1026
SRM   Can't invert....need to fix the peak-finding.  
MC1  MC1.png       pit     yaw     pos     side    butt
UL    0.872   0.986   0.160   0.054   0.000 
UR    0.176  -0.752   0.917   0.018   0.000 
LR   -1.824  -2.000   1.840   0.002   3.999 
LL   -1.128  -0.262   1.083   0.038  -0.000 
SD    0.041   0.036  -0.193   1.000  -0.001 
5.31462
MC2  MC2.png       pit     yaw     pos     side    butt
UL    1.042   0.767   0.980   0.131   0.928 
UR    0.577  -1.233   1.076  -0.134  -0.905 
LR   -1.423  -0.640   1.020  -0.146   1.050 
LL   -0.958   1.360   0.924   0.120  -1.117 
SD   -0.073  -0.164  -0.702   1.000  -0.056 
4.07827
MC3  MC3.png       pit     yaw     pos     side    butt
UL    1.595   0.363   1.152   0.166   1.107 
UR    0.025  -1.629   1.135   0.197  -0.994 
LR   -1.975   0.008   0.848   0.105   0.904 
LL   -0.405   2.000   0.865   0.074  -0.995 
SD   -0.433   0.400  -1.624   1.000   0.022 
3.64881

 

  5422   Thu Sep 15 18:24:54 2011 PaulUpdateSUSITMY and SRM Oplev current status - comparison with ITMY

Just to find out where we are currently, I plotted the ITMY and SRM oplev spectra along with the ETMY oplev spectra. ETMY seems to be very good, so comparing with this seemed useful, so we know how much we have to improve by. The SRM power spectrum appears to be around 2 orders of magnitude higher than ETMY over pretty much the whole measurement band. The ITMY power spectrum is not so bad as the SRM above about 60Hz. Next thing to do is to check the dark noise level for the ITMY and SRM QPDs.

  5423   Thu Sep 15 18:31:27 2011 PaulUpdateSUSITMY and SRM Oplev current status - comparison with ITMY

Quote:

Just to find out where we are currently, I plotted the ITMY and SRM oplev spectra along with the ETMY oplev spectra. ETMY seems to be very good, so comparing with this seemed useful, so we know how much we have to improve by. The SRM power spectrum appears to be around 2 orders of magnitude higher than ETMY over pretty much the whole measurement band. The ITMY power spectrum is not so bad as the SRM above about 60Hz. Next thing to do is to check the dark noise level for the ITMY and SRM QPDs.

 The title of this post should of course have been " ... - comparison with ETMY" not " ... - comparison with ITMY"

  5427   Thu Sep 15 22:26:32 2011 PaulUpdateSUSITMY Oplev QPD dark noise PSD

 I took a dark noise measurement for the ITMY QPD, for comparison with measurements of the oplev noise later on. Initially I was plotting the data from test points after multiplication by the oplev matrix (i.e. the OLPIT_IN1 / OLYAW_IN1), but found that the dark noise level seemed higher than the bright noise level (!?). Kiwamu realised that this is because at that test point the data is already divided by QPD SUM, thus making the dark noise level appear to be greater than the bright level, since QPD SUM is much smaller for the dark measurements. The way around this was to record the direct signals from each quadrant before the division. I took a power spectrum of the dark noise from each quadrant, then added them in quadrature, then divided by QPD SUM at the end to get an uncalibrated PSD. Next I will convert these into the equivalent for pitch and yaw noise spectra. To calibrate the plots in radians per root Hz requires some specific knowledge of the oplev path, so I won't do this until I have adjusted the path.

  5428   Thu Sep 15 22:31:44 2011 ManuelUpdateSUSSummary screen

I changed some colors on the Summary of Suspension Sensor  using my italian creativity.

I wrote a script in Python to change the thresholds for the "alarm mode" of the screen.

The script takes a GPS-format start time as the 1st argument and a duration time as the second argument.

For every channel shown in the screen, it compute the mean value during this time.

The 3rd argument is the ratio between the mean and the LOW threshold. The 4th argument is the ratio between the mean and the LOLO threshold.

Then it sets the thresholds simmetrycally for HIGH and HIHI threshold.

It does that for all channels skipping the Gains and the Off Sets because this data are not stored.

For example is ratio are 0.9 and 0.7 and the mean is 10, thresholds will be LOLO=7, LOW=9, HIGH=11, HIHI=13.

You can run the script on pianosa writing on a terminal '/opt/rtcds/caltech/c1/scripts/SUS/set_thresholds.py' and the arguments.

I already run my program with those arguments: 1000123215 600 0.9 0.7

The time is of this morning at 5:00 for 10 minutes

 

This is the help I wrote

HELP: This program set the thresholds for the "alarm mode" of the C1SUS_SUMMARY.adl medm screen.

 Written by Manuel Marchio`, visiting student from University of Pisa - INFN for the 2011 summer at Ligo-Caltech. Thrusday, 15th September 2011.

The 1st argument is the time in gps format when you want to START the mean

The 2nd argument is the DURATION

The 3rd argument is the ratio of the LOW and the HIGH thresholds. It must be in the range [0,1]

The 4th argument is the ratio of the LOLO and the HIHI thresholds. It must be in the range [0,1]

Example: path/set_thresholds.py 1000123215 600 0.9 0.7

and if the the mean is 10, thresholds will be set as LOLO=7, LOW=9, HIGH=11, HIHI=13

 

  5429   Fri Sep 16 00:08:30 2011 PaulUpdateSUSITMY Oplev QPD dark and bright noise spectra

 I tried again at plotting the ITMY_QPD noise spectra in for dark and bright operation. Before we had the strange situation where the dark noise seemed higher, but Kiwamu noticed this was caused by dividing by the SUM before the testpoint I was looking at. This time I tried just multiplying by the measured SUM for bright and dark to normalise the spectra against each other. The results looks more reasonable now, the dark noise is lower than the bright noise for a start! However, the dark noise spectrum now doesn't look the same as the one I showed in my previous post.

  5432   Fri Sep 16 14:03:53 2011 PaulUpdateSUSSRM oplev QPD noise measurement

 I checked the dark and bright noise of the SRM oplev QPD. The SRM QPD has a rather high dark level for SUM of 478 counts. The dark noise for the SRM QPD looked a little high in the plot against the bright noise (see first attachment), so I plotted the dark noise with the ITMY QPD dark noise (see second attachment). It seems that the SRM QPD has a much higher dark noise level than the ITMY! In case anyone is wondering, to make these traces I record the data from the pitch and yaw test points, then multiply by the SUM (to correct for the fact that the test point signal has already been divided by SUM). I will check the individual quadrants of the SRM QPD to see if one in particular is very noisy. If so, we/I should probably fix it.

  5435   Fri Sep 16 16:29:05 2011 kiwamuUpdateSUSf2a filters on SRM

New f2a filters were installed on SRM.

The lock of DRMI should be more stable than last night.

Quote from #5417

Once the SRM oplev project settles down, I will adjust the f2a filters on SRM too.

 

  5436   Fri Sep 16 16:34:54 2011 PaulUpdateSUSITMY SRM oplev telescope plan

I've calculated a suitable collimating telescope for the ITMY/SRM oplev laser, based on the specs for the soon-to-arrive 2mW laser (model 1122/P) available here: http://www.jdsu.com/ProductLiterature/hnlh1100_ds_cl_ae.pdf

Based on the fact that the 'beam size' value and 'divergence angle' value quoted don't match up, I am assuming that the beam radius value of 315um is _not_ the waist size value, but rather the beam size at the output coupler. From the divergence angle I calculated a 155um waist, (zR = 12cm). This gives the quoted beam size of about 316um at a distance of 8.5" away from the waist. This makes me think that the output coupler is curved and the waist is at the back of the laser, or at least 8.5" from the output coupler.

The collimating telescope gives a waist of size 1142um (zR=6.47m) at a distance of 1.427m away from the original laser waist, using the following lens combo:

 

L1 f=-0.15 @ 0.301m

L2 f=0.3 @ 0.409m

 

This should be fine to get a small enough spot size (1-2mm) on the QPDs.

 

  5437   Fri Sep 16 17:09:07 2011 PaulUpdateSUSITMX oplev plan

 I just drew a basic picture of how the ITMX oplev path could be reworked to minimise the number of optics in the path. Only possible problem with this might be the turning mirror onto the ITMX getting in the way of the collimating lenses. Should be easy to solve though. Does anyone know if there is a ITMX pick off beam I should be careful to avoid?

  5438   Fri Sep 16 17:16:15 2011 JenneUpdateSUSInput matrix diagonalization: Fail!

[Jenne, Anamaria]

I put the new matricies in from the free swinging test for the: ITMX, ITMY, ETMX, ETMY, PRM, BS

Some of the optics damped okay, but ETMX and BS were not good at all.  ETMX was ringing up when I turned on the damping.  BS wasn't, but when I gave it a kick, it wouldn't damp.  No good.

I tried ITMY, and it was totally fine, with nice damping Qs of ~5.  So, I don't know what's going on. 

Anamaria is trying a new 4x4 matrix-inverter, so we can look at the inversion of just the face osems.  We'll see how it goes. 

Since things were crappy, I did a BURT restore, so things are as they were earlier this morning.

  5439   Fri Sep 16 17:46:13 2011 kiwamuUpdateSUSSome screens fixed

The bad medm screens have been fixed. There are no blank fields and all the links are correct.

Quote from #5409

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

 

  5442   Fri Sep 16 22:11:21 2011 PaulUpdateSUSITMY transfer function

First of all I moved the lenses on the ITMY/SRM oplev path to get a smaller spot size on the QPDs. I couldn't get the beam analyzer to work though, so I don't know quite how successful this was. The software brought up the error "unable to connect to framegrabber" or something similar. I don't think the signal from the head was being read by the software. I will try to get the beam analyzer working soon so that we can characterize the other oplev lasers and get decent spot sizes on the QPDs. I searched the elog for posts about the analyzer, and found that it has been used recently, so maybe I'm just doing something wrong in using it. 

After this I measured the transfer function for the ITMY oplev yaw. I did a swept sine excitation of the ITMY in yaw with an amplitude of 500, and recorded the OSEM yaw values and the oplev yaw values. This should show a flat response, as both the QPD and the OSEMS should have flat frequency response in the measurement band. This measurement should therefore just yield a calibration from OSEM yaw to oplev yaw. If the OSEM yaw values were already calibrated for radians, we would then immediately have a calibration from oplev yaw values to radians. However, as far as I'm aware, there is not a calibration factor available from OSEM yaw values to radians. Anyway, the TF I measured did not appear to be very flat (see attached plot). Kiwamu suggested I should check the correlation between the OSEM measurements and the oplev QPD measurements - if the correlation is less than 1 the TF is not reliable. Indeed the coherence was poor for this measurement. This was probably because at frequencies above the pendulum frequency, the excitation amplitude of 500 was not enough to cause a measurable change in the optic angle. So, the plot attached is not very useful yet, but I learned something while making it.

 

  5443   Fri Sep 16 22:51:52 2011 PaulUpdateSUSCalibration plan for the oplevs

 In order to estimate the amount of noise that the oplevs are injecting into the GW channel, we first need to calibrate oplev signals in terms of angular change in the optic. I said in my previous post that there wasn't a calibration factor for OSEM values to radians, but I found that Kakeru had estimated this in 2009 - see entry 1413. However, Kakeru found that this was quite a rough estimate, and that it didn't agree with his calibrated oplev values well. He does quote the 2V/mm calibration factor for the OSEM readings though - does anyone know the provenance of this factor? I searched for OSEM calibration and found nothing.

 
Kiwamu and Suresh suggested a way to calibrate the oplevs without needing to calibrate the OSEMs in the way that Kakeru describes in entry 1413. This should give a calibration for the OSEMs _and_ the oplevs in fact. The method should be as follows:
 
1) Change the coil driver values in DC to give tip or tilt the optic. Measure the resulting change in spot position at a known distance from the optic, perhaps just using a ruler. Record the spot position and OSEM values for each coil driver value. This will definitely require a smaller spot size, so I'll implement the new telescopes first.
 
2) Knowing the length of the lever arm from the optic to the spot measurement position, we can calibrate the OSEM values to radians.
 
3) We can now put the beam onto the oplev QPD, and either change the coil driver values again in the same way (but over a smaller range), or excite the test mass in pitch or yaw, this time measuring both the OSEM values and the oplev QPD values. Since we can already convert from OSEM values to radians, we can now convert from oplev values to radians too.
 
4) I should be careful to consider the input sensing matrix for both the OSEMs and the oplevs in these measurements. Should I divide those out of the calibration to avoid that if they change the calibration factor changes too?
  5444   Fri Sep 16 23:22:36 2011 kiwamuUpdateSUSETMX input matrix : bad YAW-SIDE coupling

With the new input matrix, it looks like YAW and SIDE are not quite decoupled on ETMX.

It needs one more kick and free swinging test.

 

- - - details

 To see what exactly is going on, I changed the input matrix from the default to the new one, which Jenne computed (#5421) on ETMX.

I started putting the elements of the input matrix from POS through SIDE, one by one.

It seemed that POS and PIT worked fine. However the YAW signal looks containing a lot of the SIDE signal.

Similar to YAW, SIDE also interact with the YAW motion and somehow rings up both YAW and SIDE signals as Jenne reported ( #5438).

So right now the YAW and SIDE rows are partially reburted to the default elements in order to avoid ringing up.

Quote from #5438

but ETMX and BS were not good at all.  ETMX was ringing up when I turned on the damping. 

 

  5446   Sat Sep 17 02:07:10 2011 kiwamuUpdateSUSETMX input matrix : bad YAW-SIDE coupling

Excited all the optics. They will be automatically back after 5 hours.

Sat Sep 17 02:02:07 PDT 2011
1000285342

Quote from #5444

It needs one more kick and free swinging test.

 

  5448   Sun Sep 18 14:08:52 2011 ranaUpdateSUSCalibration plan for the oplevs

We don't need a high quality calibration for the optical levers. ~50% accuracy is fine.

For that you can use the OSEM calibration of ~1.7 V/mm (its less than 2 since the OSEMs have been degrading) or you can use the cavity power method that Kakeru used; it worked just fine. There's no benefit in trying for a 1% number for optical levers.

  5452   Mon Sep 19 01:07:32 2011 kiwamuUpdateSUSf2a filters on ITMs and ETMX

The f2a filters were installed on ITMs and ETMX.

Now all of the suspensions has the f2a filters.

  5457   Mon Sep 19 12:23:30 2011 PaulUpdateSUSITMY and SRM oplev beam size reduced + next steps

I replaced the lenses that were there with a -150mm lens followed by a +250mm lens. This gave a significantly reduced beam size at the QPDs. With the beam analyzer up and running it should be possible to optimize this later this afternoon. Next I will remove the SRM QPD from the path and make measurements of the beam spot position movement and corresponding OSEM values for different DC mirror offsets. I will then repeat the process for ITMY.

  5458   Mon Sep 19 13:13:10 2011 PaulUpdateSUSITMY oplev available for use: SRM not for the moment

 I've got the bench set up for the measurement of the beam spot change with DC SRM alignment offsets. The ITMY oplev is aligned and fine to use, but the SRM one isn't until further notice (probably a couple of hours).

  5460   Mon Sep 19 15:30:22 2011 PaulUpdateSUSSRM oplev OSEM yaw calibration curve

 I made the first measurements towards oplev calibration measurements: calibrating the oplevs in SRM YAW. The measurements seemed fine, I had a range of between -1.5 and 1.5 in SRM DC alignment before clipping on mirrors on the oplev bench became a problem. This seemed to be plenty to get a decent fit for the spot position against DC alignment value - see attached plot. The fitted gradient was -420um oplev yaw count. I calculated oplev yaw values as UL+LL-UR-LR. Pitch next.

  5461   Mon Sep 19 15:41:48 2011 JenneUpdateSUSSUS diag stuff... just so I remember what I'm doing

The following optics were kicked:
ETMX
Mon Sep 19 15:39:44 PDT 2011
1000507199

  5465   Mon Sep 19 16:56:29 2011 PaulUpdateSUSSRM oplev pitch calibration

 Same measurements for SRM pitch (as previously done for yaw in entry 5460) are complete. The QPD is back in the path and aligned. I will be doing the same measurements for ITMY now though, so please ask before activating the SRM or ITMY oplev servos, as I may be blocking the beam.

  5466   Mon Sep 19 17:45:39 2011 ranaUpdateSUSSome screens fixed

Quote:

Kiwamu:       The bad medm screens have been fixed. There are no blank fields and all the links are correct.

Quote from #5409

I've found that a few of the screens still have Whited-Out fields due to naming changes (OL SUM and ALS-> TM OFFSET). I attach a screen shot of it.

The OL screens have the wrong SUM names and the IFO ALIGN screen is pointing to the wrong SUS screens.

 

 Really? I found this one with ~15 seconds of clicking around.

Untitled.png

  5467   Mon Sep 19 18:05:27 2011 ranaUpdateSUSSummary screen

Quote:

I changed some colors on the Summary of Suspension Sensor  using my italian creativity.

I wrote a script in Python to change the thresholds for the "alarm mode" of the screen.

I've started to fix up the script somewhat (as a way to teach myself some more python):

* moved all of the SUS Summary screen scripts into SUS/SUS_SUMMARY/

* removed the hardcoded channel names (a list of 190 hand-typed names !!!!!!!)

* fixed it to use NDS2 instead of try to use the NDS2 protocol on fb:8088 (which is an NDS1 only machine)

* it was trying to set alarms for the SUS gains, WDs, Vmons, etc. using the same logic as the OSEM PD values. This is non-sensical. We'll need to make a different logic for each type of channel.

New script is called setSensors.py. There are also different scripts for each of the different kinds of fields (gains, sensors, vmons, etc.)

Some Examples:

pianosa:SUS_SUMMARY 0> ./setDogs.py 3 5
Done writing new values.

sussum.png

  5468   Mon Sep 19 20:56:36 2011 PaulSummarySUSRemaining SRM and ITMY OSEMs calibrations

 

I've now taken data for the pitch and yaw calibrations for the OSEMs of SRM and ITMY. Until such time as I know what the calibrated oplev noise spectra are like, I'm leaving the servo gains at zero.

I estimate the length of the lever arm from SRM to measurement position to be 3.06m, and the length of the lever arm from the ITMY to the measurement position to be 3.13m.

From the fits shown on the attached plots, this gives the following calibration factors for the SRM and ITMY OSEMs pitch and yaw counts (i.e. counts from channels such as SUS-ITMY_ULSEN_SW2 multiplied by a matrix of 1s and -1s) to pitch and yaw angle:

 

SRM PITCH: 1 OSEMs pitch count = 11.74 microradians

SRM YAW: 1 OSEMs yaw count = 12.73 microradians

 

ITMY PITCH: 1 OSEMs pitch count = 13.18 microradians

ITMY YAW: 1 OSEMs yaw count = 13.52 microradians

 

Next step is to do some DC offsets with the oplev paths back in place to get the final calibration between OSEMs counts and oplev counts, thus finally getting a conversion factor from oplev counts to radians.

I noticed while taking these measurements that the DC offsets I put on ITMY caused around 5 times larger change in angle than those on the SRM. The different path length is not enough to account for this, so I propose that the actuation is working differently for the two. I guess this should be taken into account when designing the output matrices (unless the control is passed through a different output matrix than the DC offsets?). I'll quantify the difference shortly, and write a conversion factor between output alignment count (e.g. SUS-ITMY_PIT_COMM) and angle.

 

 

  5471   Mon Sep 19 22:47:44 2011 JenneUpdateSUSSUS diag stuff... just so I remember what I'm doing

 The last person out tonight should run the following scripts:

In Matlab: 

/opt/rtcds/caltech/c1/scripts/SUS/peakFit/writeMultiSUSinmat.m

In command line:

/opt/rtcds/caltech/c1/scripts/SUS/freeswing all

 

Then in the morning, someone should do a BURT restore to early today (to get the default matricies back), and also restore the watchdogs.

Thanks!
 

  5475   Tue Sep 20 03:12:14 2011 AnamariaUpdateSUSJenne's Scripts started

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

  5476   Tue Sep 20 04:12:26 2011 JenneUpdateSUSJenne's Scripts started

Quote:

I followed Jenne's instructions, ran the matrix filler script and then set the optics to freeswing. Someone has to burt resture and damp them in the morning.

 Thanks!  I'll give them a little more time, then restore things.

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