This afternoon I removed the old periscope from CR0 and installed a new one with finely adjustable mount, like those in the new chamber. I realigned the optical lever to the horizontal refererence.

2017-03-07

• 11:08am, in chamber CR0
• 11:09am, roughing pump on
• 11:23am turbo pump on
• 3:37pm, pumps stopped, the turbo is saturating CR1

2017-03-08

• 8:00am pumps restarted
• Excitations

  • Quiet time before excitation: 1173048953
    Excitation broadband: 1173048986
    Quiet time after excitation: 1173049018

  • Quiet time before excitation: 1173050248
    Excitation broadband: 1173050280
    Quiet time after excitation: 1173050312

  • Quiet time before excitation: 1173051542
    Excitation broadband: 1173051574
    Quiet time after excitation: 1173051606

  • Quiet time before excitation: 1173052836
    Excitation broadband: 1173052868
    Quiet time after excitation: 1173052900

  • Quiet time before excitation: 1173054130
    Excitation broadband: 1173054163
    Quiet time after excitation: 1173054195

  • Quiet time before excitation: 1173055425
    Excitation broadband: 1173055457
    Quiet time after excitation: 1173055489

2017-03-09

• 10:10am, pumps off

2017-03-07

• 10:57am, in chamber
  • S1600469 in CR1
  • S1600471 in CR2
  • S1600481 in CR3
  • S1600483 in CR4
• 11:02am, roughing pump on
• 11:11am, turbo pump on
• Excitations

  • Quiet time before excitation: 1172968827
    Excitation broadband: 1172968862
    Quiet time after excitation: 1172968927

  • Quiet time before excitation: 1172970757
    Excitation broadband: 1172970792
    Quiet time after excitation: 1172970857

  • Quiet time before excitation: 1172972687
    Excitation broadband: 1172972723
    Quiet time after excitation: 1172972788

  • Quiet time before excitation: 1172974618
    Excitation broadband: 1172974653
    Quiet time after excitation: 1172974718

  • Quiet time before excitation: 1172976548
    Excitation broadband: 1172976583
    Quiet time after excitation: 1172976648

  • Quiet time before excitation: 1172978478
    Excitation broadband: 1172978513
    Quiet time after excitation: 1172978578

  • Quiet time before excitation: 1172980408
    Excitation broadband: 1172980443
    Quiet time after excitation: 1172980508

  • Quiet time before excitation: 1172982338
    Excitation broadband: 1172982373
    Quiet time after excitation: 1172982438

2017-03-08

• 8:00am pumps off, gate valve closed

2017-03-03

• 1:00pm, in chamber, realigned optical lever to get as close as possible to the edge of the disk
• 1:02pm, roughing pump on
• 1:14pm, turbo pump on
• Excite

  • Quiet time before excitation: 1172633160
    Excitation broadband: 1172633192
    Quiet time after excitation: 1172633224

  • Quiet time before excitation: 1172634454
    Excitation broadband: 1172634486
    Quiet time after excitation: 1172634518

  • Quiet time before excitation: 1172635748
    Excitation broadband: 1172635781
    Quiet time after excitation: 1172635813

  • Quiet time before excitation: 1172637043
    Excitation broadband: 1172637075
    Quiet time after excitation: 1172637107

  • Quiet time before excitation: 1172638337
    Excitation broadband: 1172638369
    Quiet time after excitation: 1172638401

  • Quiet time before excitation: 1172639631
    Excitation broadband: 1172639663
    Quiet time after excitation: 1172639695

2017-03-06

• 10:18am, pumps off

2017-03-03

• 12:45pm, in chamber
  • S1600453 in CR3
  • S1600490 in CR4
• 12:45pm roughing pump on
• 12:56pm, turbo pump on
• Excitation

  • Quiet time before excitation: 1172620986
    Excitation broadband: 1172621021
    Quiet time after excitation: 1172621086

  • Quiet time before excitation: 1172622916
    Excitation broadband: 1172622951
    Quiet time after excitation: 1172623016

  • Quiet time before excitation: 1172624846
    Excitation broadband: 1172624881
    Quiet time after excitation: 1172624946

  • Quiet time before excitation: 1172626776
    Excitation broadband: 1172626811
    Quiet time after excitation: 1172626876

  • Quiet time before excitation: 1172628706
    Excitation broadband: 1172628742
    Quiet time after excitation: 1172628807

  • Quiet time before excitation: 1172630638
    Excitation broadband: 1172630673
    Quiet time after excitation: 1172630738

  • Quiet time before excitation: 1172632568
    Excitation broadband: 1172632603
    Quiet time after excitation: 1172632668

  • Quiet time before excitation: 1172634498
    Excitation broadband: 1172634534
    Quiet time after excitation: 1172634599

2017-03-06

• 10:19am, gate valve closed, pumps off

The turbo pump of the CR0 chamber runs at 833 Hz. It causes vibrations that pollute the measurements in the CR1-4 chamber. In particular CR1 is extremely sensitive and the line is highly up-converted. It's not clean why CR1 is more sensitive than CR2-3-4.

2017-03-02

• 9:31am, in chamber, removed ND from path 2-4
  • S1600456 in CR1
  • S1600458 in CR2
  • S1600461 in CR3
  • S1600491 in CR4
• 9:45am roughing pump on
• 9:55am turbo pump on
• Excitations

  • Quiet time before excitation: 1172530103
    Excitation broadband: 1172530139
    Quiet time after excitation: 1172530204

  • Quiet time before excitation: 1172532034
    Excitation broadband: 1172532069
    Quiet time after excitation: 1172532134

  • Quiet time before excitation: 1172533964
    Excitation broadband: 1172533999
    Quiet time after excitation: 1172534064

  • Quiet time before excitation: 1172535894
    Excitation broadband: 1172535929
    Quiet time after excitation: 1172535994

  • Quiet time before excitation: 1172537824
    Excitation broadband: 1172537859
    Quiet time after excitation: 1172537924

  • Quiet time before excitation: 1172539754
    Excitation broadband: 1172539789
    Quiet time after excitation: 1172539854

  • Quiet time before excitation: 1172541684
    Excitation broadband: 1172541719
    Quiet time after excitation: 1172541784

  • Quiet time before excitation: 1172543614
    Excitation broadband: 1172543649
    Quiet time after excitation: 1172543714

2017-03-03

• 9:30am, gate valve closed, pumps stopped, venting

2017-03-01

• 10:10am, in chamber, added neutral densities
  • S1600469 in CR1
  • S1600471 in CR2
  • S1600481 in CR3
  • S1600483 in CR4
• 10:12am, roughing pump on, clamps on
• 10:22am, turbo pump on
• Excitations:

  • Quiet time before excitation: 1172438462
    Excitation broadband: 1172438497
    Quiet time after excitation: 1172438562

  • Quiet time before excitation: 1172440392
    Excitation broadband: 1172440427
    Quiet time after excitation: 1172440492

  • Quiet time before excitation: 1172442322
    Excitation broadband: 1172442357
    Quiet time after excitation: 1172442422

  • Quiet time before excitation: 1172444252
    Excitation broadband: 1172444287
    Quiet time after excitation: 1172444352

  • Quiet time before excitation: 1172446182
    Excitation broadband: 1172446217
    Quiet time after excitation: 1172446282

  • Quiet time before excitation: 1172448112
    Excitation broadband: 1172448148
    Quiet time after excitation: 1172448213

  • Quiet time before excitation: 1172450044
    Excitation broadband: 1172450079
    Quiet time after excitation: 1172450144

  • Quiet time before excitation: 1172451974
    Excitation broadband: 1172452009
    Quiet time after excitation: 1172452074

2017-03-02

• 9:00am, vented, samples removed

2017-02-28

• 2:19pm, installed in CR0, balanced, with 1/2" inserts facing down
  • It looks dusty and there is a fingerprint on the edge. I didn't clean it
• 2:21pm, roughing pump on
• 2:35pm, turbo pump on
• Excitations:

  • Quiet time before excitation: 1172377933
    Excitation broadband: 1172377965
    Quiet time after excitation: 1172378027

  • Quiet time before excitation: 1172381657
    Excitation broadband: 1172381689
    Quiet time after excitation: 1172381751

  • Quiet time before excitation: 1172385381
    Excitation broadband: 1172385414
    Quiet time after excitation: 1172385476

  • Quiet time before excitation: 1172389106
    Excitation broadband: 1172389138
    Quiet time after excitation: 1172389200

  • Quiet time before excitation: 1172392830
    Excitation broadband: 1172392863
    Quiet time after excitation: 1172392925

  • Quiet time before excitation: 1172396555
    Excitation broadband: 1172396587
    Quiet time after excitation: 1172396649

2017-03-01

• 9:36am, pumps stopped

2017-03-02

• 9:00am. The laser beam was probably hitting one of the glued inserts. Checked that te disk is not touching, moved the ESD a bit lower
• 9:04am, roughing pump on
• 9:17am, turbo pump on
• 1:50pm, pumps off

2017-02-28

• 11:20am, in chamber
  • S1600463 in CR1
  • S1600466 in CR2
  • S1600475 in CR3
  • S1600476 in CR4
• 2:10pm, roughing pump on
• 2:20pm, turbo pump on
• Excitations

  • Quiet time before excitation: 1172366632
    Excitation broadband: 1172366667
    Quiet time after excitation: 1172366732

  • Quiet time before excitation: 1172373962
    Excitation broadband: 1172373997
    Quiet time after excitation: 1172374062

  • Quiet time before excitation: 1172381292
    Excitation broadband: 1172381327
    Quiet time after excitation: 1172381392

  • Quiet time before excitation: 1172388622
    Excitation broadband: 1172388657
    Quiet time after excitation: 1172388722

2017-03-01

• 9:31am, venting

2017-02-27

• 12:59pm, installed in chamber CR0, balanced
• 1:00pm, roughing pump on
• 1:13pm, turbo pump on
• 3:04pm, stopped pumps

2017-02-27

• 8:40am, in chamber, balanced
  • S1600453 in CR1
  • S1600491 in CR2 (i meant to install 490, but got confused)
• 10:23am, roughing pump on, clamps on
• 10:32am, turbo pump on
• 3:01pm, something is wrong with CR1 (the 666 Hz line due to the turbo pump is very large and saturates the QPD signals). Venting
• 4:11pm in chamber
  • S1600453 in CR1
  • S1600490 in CR2
• 4:12pm roughing pump on, clamps on
• 4:20pm turbo pump on
• Excitations

  • Quiet time before excitation: 1172290836
    Excitation broadband: 1172290871
    Quiet time after excitation: 1172290936

  • Quiet time before excitation: 1172292766
    Excitation broadband: 1172292801
    Quiet time after excitation: 1172292866

  • Quiet time before excitation: 1172294696
    Excitation broadband: 1172294731
    Quiet time after excitation: 1172294796

  • Quiet time before excitation: 1172296626
    Excitation broadband: 1172296661
    Quiet time after excitation: 1172296726

  • Quiet time before excitation: 1172298556
    Excitation broadband: 1172298591
    Quiet time after excitation: 1172298656

  • Quiet time before excitation: 1172300486
    Excitation broadband: 1172300522
    Quiet time after excitation: 1172300587

  • Quiet time before excitation: 1172302417
    Excitation broadband: 1172302452
    Quiet time after excitation: 1172302518

  • Quiet time before excitation: 1172304348
    Excitation broadband: 1172304383
    Quiet time after excitation: 1172304448

2017-02-28

• 11:08am, vented

It's possible to build an analytical model of the resonant frequencies of a simple thin disk. For example, see J. Sound and Vibrations 188, 685 (1995), section 2

The solutions are given in term of Bessel functions:

where J is a Bessel function of the first kind, and I a modified Bessel function of the first kind, a is the disk radius.

The coefficient Cmn and the eigenvalue can be found as solution of the following two equations

Then the eigenfrequencies are given by

where rho is the material density, h the disk thickness and D the flexural rigidity

where E is the material Young's modulus and nu the Poisson's ratio.

From all those results we can conclude that the frequency scaling with respect to disk radius and thickness are very simple:

• the frequencies scale linearly with the thickness
• the frequencies scale inversely proportionally to the square of the radius

Also, the frequencies scales as sqrt(E/rho)

The dependency on the Poisson's ratio is more complex since nu is involved in the eigenfrequency equation shown above.

Unfortunately the thin disk model does not exactly match the COMSOL results: deviations of few tens of Hz are present, probaly due to the thin disk approximation. The COMSOL model is more accurate to match the experimental frequencies.

However, I checked that the eigenfrequencies predicted by COMSOL also scales as predicted with thickness and radius.

Using the measurements on the six samplex we got from Mark Optics, after annealing, I was able to tune the COMSOL model to fit all measured frequencies within 6 Hz. I chose to change the disk thickness (since diameter and Young'r modulus are degenerate) and the Poisson's ratio. 

Here is an example of the difference between the measured and modeled frequencies:

The table below summarizes the best fit for each of the disks

Since the material is the same, I would expect the Poisson's ratio to be constant. So for future modeling I'm using the average of the values above: 0.166

Below the measured Q values of the six Suprasil 313 substrates, with polished edges, after annealing at 900 degrees C for 9 hours.

They are all consistently at a level of 100e6 at 1 KHz and showing a similar frequency dependency going down to a about 30e6 at 20-30 kHz. The only exception is S1600522 which has clearly lower Q values at all frequencies.

Below a comparison of the substrate loss angles compared wiht Steve Penn's model:

2017-02-24

• 10:50am, in chamber, balanced, added neutral density to laser on the 1/3 path
  • S1600456 in CR1
  • S1600458 in CR2
  • S1600461 in CR3
  • S1600491 in CR4
• 10:56am, roughing pump on, clamps on
• 11:05am, turbo pump on
• Excitations

  • Quiet time before excitation: 1172009197
    Excitation broadband: 1172009232
    Quiet time after excitation: 1172009297

  • Quiet time before excitation: 1172011127
    Excitation broadband: 1172011162
    Quiet time after excitation: 1172011227

  • Quiet time before excitation: 1172013057
    Excitation broadband: 1172013092
    Quiet time after excitation: 1172013157

  • Quiet time before excitation: 1172014987
    Excitation broadband: 1172015022
    Quiet time after excitation: 1172015087

  • Quiet time before excitation: 1172016917
    Excitation broadband: 1172016952
    Quiet time after excitation: 1172017017

  • Quiet time before excitation: 1172018847
    Excitation broadband: 1172018882
    Quiet time after excitation: 1172018947

  • Quiet time before excitation: 1172020777
    Excitation broadband: 1172020812
    Quiet time after excitation: 1172020877

  • Quiet time before excitation: 1172022707
    Excitation broadband: 1172022742
    Quiet time after excitation: 1172022807

2017-02-27

• 8:32am venting

2017-02-23

• 10:35am in chamber, balanced
  • S1600523 in bay 1
  • S1600524 in bay 2
• 10:45am, roughing pump on, clamps on
• 10:55am, turbo pump on
• Excitations:

  • Quiet time before excitation: 1171925035
    Excitation broadband: 1171925070
    Quiet time after excitation: 1171925085

  • Quiet time before excitation: 1171935915
    Excitation broadband: 1171935950
    Quiet time after excitation: 1171935965

  • Quiet time before excitation: 1171946795
    Excitation broadband: 1171946830
    Quiet time after excitation: 1171946845

  • Quiet time before excitation: 1171957675
    Excitation broadband: 1171957710
    Quiet time after excitation: 1171957725

2017-02-24

• 8:40am, gate valve close, pumps off, venting

2017-02-22

• 2:59pm, in chamber, balanced, removed all neutral densities
• 3:02pm, roughing pump on, clamps on
• 3:11pm, turbo pump on
• Excitations

  • Quiet time before excitation: 1171847838
    Excitation broadband: 1171847873
    Quiet time after excitation: 1171847888

  • Quiet time before excitation: 1171858718
    Excitation broadband: 1171858754
    Quiet time after excitation: 1171858769

  • Quiet time before excitation: 1171869599
    Excitation broadband: 1171869634
    Quiet time after excitation: 1171869649

  • Quiet time before excitation: 1171880479
    Excitation broadband: 1171880514
    Quiet time after excitation: 1171880530

2017-02-23

• 10:22am, gate valve closed, pumps off, venting

1. created a single interface to move the picomotors in front of QPD1 ... QPD4
   • the command qpdcenter will open an interactive python shell to control the picomotors
2. two scripts for automatic excitations are saved in /opt/rtcds/userapps/CyMAC/src/auto_excite*.py
   • they must run on the cymac. But they can be started from the control station using the commands autoexcite0 and autoexcite14
   • before starting the commands, set the parameters in the file. The two commands edit_autoexcite0 and edit_autoexcite14 will open the correct files
   • a log file of the excitation times will be saved
   • the scripts will check if there is an excitation going
3. the two commands noise0 and noise14 can be used to start awggui to inject the correct noise
4. updated the autocentering scripts, so that only one instance can run at a time.
   • launch them with the commands autocenter0 and autocenter14

2017-02-19

• 11:28am an chamber:
  • S1600458 in CR1
  • S1600474 in CR2
  • S1600491 in CR3
  • empty CR4
• 11:46am roughing pump on, clamps on
• 11:57am turbo pump on
• Excitations:

  • Quiet time before excitation: 1171579753
    Excitation (broad band) at 1171579788 (60 s)
    Quiet time after excitation: 1171579854

  • Quiet time before excitation: 1171581684
    Excitation (broad band) at 1171581719 (60 s)
    Quiet time after excitation: 1171581784

  • Quiet time before excitation: 1171583614
    Excitation (broad band) at 1171583649 (60 s)
    Quiet time after excitation: 1171583714

  • Quiet time before excitation: 1171585545
    Excitation (broad band) at 1171585580 (60 s)
    Quiet time after excitation: 1171585645

  • Quiet time before excitation: 1171587475
    Excitation (broad band) at 1171587510 (60 s)
    Quiet time after excitation: 1171587575

  • Quiet time before excitation: 1171589405
    Excitation (broad band) at 1171589440 (60 s)
    Quiet time after excitation: 1171589505

  • Quiet time before excitation: 1171591335
    Excitation (broad band) at 1171591370 (60 s)
    Quiet time after excitation: 1171591435

  • Quiet time before excitation: 1171593265
    Excitation (broad band) at 1171593300 (60 s)
    Quiet time after excitation: 1171593365

2017-02-21

• 10:30am, gate valve closed, pumps stopped, venting

2017-02-18

• 9:54am in chamber, balanced
  • S1600469 in CR1
  • S1600471 in CR2
  • S1600481 in CR3
  • S1600483 in CR4
• 10:00am, roughing pump on, clamps on
• 10:13am, turbo pump on
• Excitations

  • Quiet time before excitation: 1171492847
    Excitation (broad band) at 1171492882 (60 s)
    Quiet time after excitation: 1171492947

  • Quiet time before excitation: 1171494777
    Excitation (broad band) at 1171494813 (60 s)
    Quiet time after excitation: 1171494878

  • Quiet time before excitation: 1171496708
    Excitation (broad band) at 1171496743 (60 s)
    Quiet time after excitation: 1171496808

  • Quiet time before excitation: 1171498638
    Excitation (broad band) at 1171498673 (60 s)
    Quiet time after excitation: 1171498738

  • Quiet time before excitation: 1171500568
    Excitation (broad band) at 1171500603 (60 s)
    Quiet time after excitation: 1171500668

  • Quiet time before excitation: 1171502498
    Excitation (broad band) at 1171502533 (60 s)
    Quiet time after excitation: 1171502598

  • Quiet time before excitation: 1171504428
    Excitation (broad band) at 1171504463 (60 s)
    Quiet time after excitation: 1171504528

  • Quiet time before excitation: 1171506358
    Excitation (broad band) at 1171506393 (60 s)
    Quiet time after excitation: 1171506458

• More excitations:

  • Quiet time before excitation: 1171509354
    Excitation (broad band) at 1171509389 (60 s)
    Quiet time after excitation: 1171509454

  • Quiet time before excitation: 1171511284
    Excitation (broad band) at 1171511319 (60 s)
    Quiet time after excitation: 1171511384

  • Quiet time before excitation: 1171513214
    Excitation (broad band) at 1171513249 (60 s)
    Quiet time after excitation: 1171513314

  • Quiet time before excitation: 1171515144
    Excitation (broad band) at 1171515179 (60 s)
    Quiet time after excitation: 1171515244

  • Quiet time before excitation: 1171517074
    Excitation (broad band) at 1171517109 (60 s)
    Quiet time after excitation: 1171517174

  • Quiet time before excitation: 1171519004
    Excitation (broad band) at 1171519039 (60 s)
    Quiet time after excitation: 1171519104

  • Quiet time before excitation: 1171520934
    Excitation (broad band) at 1171520969 (60 s)
    Quiet time after excitation: 1171521034

  • Quiet time before excitation: 1171522864
    Excitation (broad band) at 1171522899 (60 s)
    Quiet time after excitation: 1171522964

2017-02-19

• 11:11am, gate valve closed, pumps stopped, venting
   

Since I had recurrent problems with the picomotors used for QPD3, I swapped them with another Newport motorized mirror that was previously used in the Crackle1 experiment. This is the same model used for the other three QPD centering. Everything looks to be working fine now.

I also realigned all optical levers and swapped out an iris with a smaller one, to avoid beam clipping. All beam paths look clear now.

2017-02-16

• 10:17am in chamber
  • S1600453 in CR1
  • S1600456 in CR2
  • S1600461 in CR3
  • S1600490 in CR4
• Notes:
  • added ND03 on path to CR1 and CR3, since QPD were saturating
  • there is something wrong with CR1, the spectrum is very noisy. I checked that there is no clipping of the beam. I also tried to move the spot on the disk, without change. Maybe the disk is touching?
• 10:18am, roughing pump on, clamps on
• 10:21am, turbo pump on
• Excitations: (NOTE: bay 1 noise spectrum is very bad. The autocetering of bay 3 failed, so the QPD was not centered for most of the time)

  • Quiet time before excitation: 1171326574
    Excitation (broad band) at 1171326609 (60 s)
    Quiet time after excitation: 1171326674

  • Quiet time before excitation: 1171328504
    Excitation (broad band) at 1171328539 (60 s)
    Quiet time after excitation: 1171328604

  • Quiet time before excitation: 1171330434
    Excitation (broad band) at 1171330469 (60 s)
    Quiet time after excitation: 1171330534

  • Quiet time before excitation: 1171332364
    Excitation (broad band) at 1171332399 (60 s)
    Quiet time after excitation: 1171332465

  • Quiet time before excitation: 1171334295
    Excitation (broad band) at 1171334330 (60 s)
    Quiet time after excitation: 1171334395

  • Quiet time before excitation: 1171336225
    Excitation (broad band) at 1171336260 (60 s)
    Quiet time after excitation: 1171336325

  • Quiet time before excitation: 1171338155
    Excitation (broad band) at 1171338191 (60 s)
    Quiet time after excitation: 1171338256

  • Quiet time before excitation: 1171340086
    Excitation (broad band) at 1171340121 (60 s)
    Quiet time after excitation: 1171340186

2017-02-17

• 8:43am gate valve closed, pump stopped, venting slowly
• the measurements carried out last night didn't look very good, mostly because it seems that the picomotor of QPD3 got crazy and was shaking too much the bench
• 12:19pm, balanced again, roughing pump on. Added ND03 and ND04 to lasers to avoid QPD saturations
• 12:49pm, turbo pump on
• Excitations:

  • Quiet time before excitation: 1171425425
    Excitation (broad band) at 1171425460 (60 s)
    Quiet time after excitation: 1171425525

  • Quiet time before excitation: 1171427355
    Excitation (broad band) at 1171427390 (60 s)
    Quiet time after excitation: 1171427455

  • Quiet time before excitation: 1171429285
    Excitation (broad band) at 1171429320 (60 s)
    Quiet time after excitation: 1171429385

  • Quiet time before excitation: 1171431215
    Excitation (broad band) at 1171431250 (60 s)
    Quiet time after excitation: 1171431315

  • Quiet time before excitation: 1171433145
    Excitation (broad band) at 1171433180 (60 s)
    Quiet time after excitation: 1171433245

  • Quiet time before excitation: 1171435075
    Excitation (broad band) at 1171435110 (60 s)
    Quiet time after excitation: 1171435176

  • Quiet time before excitation: 1171437006
    Excitation (broad band) at 1171437041 (60 s)
    Quiet time after excitation: 1171437106

  • Quiet time before excitation: 1171438936
    Excitation (broad band) at 1171438971 (60 s)
    Quiet time after excitation: 1171439036

2017-02-18

• 9:34am, gate valve closed, pumps stopped, venting

2017-02-16

• 10:06am, in chamber CR0, balanced
• 10:07am, roughing pump on
• 10:31am, turbo pump on
• Excitations

  • Quiet time before excitation: 1171326606
    Excitation (broad band) at 1171326638 (60 s)
    Quiet time after excitation: 1171326700

  • Quiet time before excitation: 1171328530
    Excitation (broad band) at 1171328562 (60 s)
    Quiet time after excitation: 1171328624

  • Quiet time before excitation: 1171330454
    Excitation (broad band) at 1171330487 (60 s)
    Quiet time after excitation: 1171330549

  • Quiet time before excitation: 1171332379
    Excitation (broad band) at 1171332411 (60 s)
    Quiet time after excitation: 1171332473

  • Quiet time before excitation: 1171334303
    Excitation (broad band) at 1171334335 (60 s)
    Quiet time after excitation: 1171334397

  • Quiet time before excitation: 1171336227
    Excitation (broad band) at 1171336259 (60 s)
    Quiet time after excitation: 1171336321

  • Quiet time before excitation: 1171338151
    Excitation (broad band) at 1171338184 (60 s)
    Quiet time after excitation: 1171338246

  • Quiet time before excitation: 1171340076
    Excitation (broad band) at 1171340108 (60 s)
    Quiet time after excitation: 1171340170

2017-02-17

• 8:36am pump stopped

New substrates from Mark Optics, round, with polished edges

2017-02-14

• 3:35pm in new chamber
  • S1600519 in bay 1
  • S1600520 in bay 2
  • S1600521 in bay 3
  • S1600522 in bay 4
• 3:38pm, roughing pump on, clamps on
• 3:48pm, turbo pump on
• Excitations:

  • Quiet time before excitation: 1171158544
    Excitation (broad band) at 1171158579 (60 s)
    Quiet time after excitation: 1171158644

  • Quiet time before excitation: 1171173074
    Excitation (broad band) at 1171173109 (60 s)
    Quiet time after excitation: 1171173174

  • Quiet time before excitation: 1171187604
    Excitation (broad band) at 1171187639 (60 s)
    Quiet time after excitation: 1171187704

• NOTE: bay 4 was not excited

2017-02-15

• 3:16pm, gate valve closed, pump stopped, venting

2017-02-14

• 2:32pm, in chamber (CR0), balanced
• 2:33pm roughing pump on
• 2:45pm, turbo pump on
• Excitations:

  • Quiet time before excitation: 1171161389
    Excitation (broad band) at 1171161421 (60 s)
    Quiet time after excitation: 1171161483

  • Quiet time before excitation: 1171172313
    Excitation (broad band) at 1171172345 (60 s)
    Quiet time after excitation: 1171172407

  • Quiet time before excitation: 1171183237
    Excitation (broad band) at 1171183269 (60 s)
    Quiet time after excitation: 1171183331

  • Quiet time before excitation: 1171194161
    Excitation (broad band) at 1171194193 (60 s)
    Quiet time after excitation: 1171194255

  • Quiet time before excitation: 1171205085
    Excitation (broad band) at 1171205117 (60 s)
    Quiet time after excitation: 1171205179

2017-02-15

• 3:19pm, pumps stopped, venting

I did two set of measurements with the new coated samples from Montreal. I reshuffled the position in the two measurements. In both cases, the measurement being performed in bay 4 was bad, in the sense that it was very hard to see excited modes. Since the two measurements were carried out with two different disks, it's clear it is a problem with that setup.

SOLVED: there was a connection problem for the DAC output signal controlling the switch

REALLY SOLVED: it was not a cabling issue. The power supply for the switching box had the current limiter on: when all four switches are closed, the box drain about 270mA, which is more than the limit of 250mA. Therefore the power supply voltage dropped and only three switches were actually closed. I switched the power supply to 500mA range and maxed the current limit. Now all four switches are working properly

The ring motion up and down was not very smooth, again due to friction on the centering pins.

So, after centering the rings using the pins and securing the rings to the translation stage, I removed all pins.

Now the motion up and down is very smooth.

I still have to fine tune the amount of steps that are needed to go up and down.

However, initial tests don't show a good repeatability of the positioning. My main suspect is that the vibration caused by the picomotor cause the disks to slip on the silicon lens. Indeed, when the disks are sitting on the rings, one can clearly hear them "rattle".

This afternoon I installed the picomotor and the translation stage that will be used to move the retaining rings up and down. No partciular problem: I only had to add some small aluminum foil shims between the ear of some rings and the square plate, to make the rings as horizontal as possible.

I tested the motion: with 300000 steps it's possible to move the rings all the way from the parked (down) position, to the up position. I also checked that when the rings are up, I can place four substarates and they fall properly into the alignment groove. Since the maximum speed of the picomotor is 2000 steps/s, it takes 150 seconds to move up and down the ring. 

Finally, positive steps means that the rings are moving up, negative that they're moving down.

I raeligned the optical levers to the position I obtained by centering the samples with the rings. I haven't tested the repeatability yet.

2017-02-09

• 2:30pm, samples installed in the chamber:
  • S1600489 in bay 1
  • S1600490 in bay 2
  • S1600491 in bay 3
  • S1600492 in bay 4
• 2:35pm, roughing pump on
• 2:45pm, pressure is <1 Torr, turbo pump on
• 4:19pm, pressure is 7.2e-6:
  • but I forgot to clamp the lid!
  • added four clamps at 4:22pm
  • pressure seems to be going down again
• Excitations

  • Quiet time before excitation: 1170737383
    Excitation (broad band) at 1170737418 (60 s)
    Quiet time after excitation: 1170737483

  • Quiet time before excitation: 1170739313
    Excitation (broad band) at 1170739349 (60 s)
    Quiet time after excitation: 1170739414

  • Quiet time before excitation: 1170741244
    Excitation (broad band) at 1170741279 (60 s)
    Quiet time after excitation: 1170741344

  • Quiet time before excitation: 1170743174
    Excitation (broad band) at 1170743210 (60 s)
    Quiet time after excitation: 1170743275

  • Quiet time before excitation: 1170745105
    Excitation (broad band) at 1170745140 (60 s)
    Quiet time after excitation: 1170745205

  • Quiet time before excitation: 1170747035
    Excitation (broad band) at 1170747070 (60 s)
    Quiet time after excitation: 1170747135

  • Quiet time before excitation: 1170748965
    Excitation (broad band) at 1170749000 (60 s)
    Quiet time after excitation: 1170749065

  • Quiet time before excitation: 1170750896
    Excitation (broad band) at 1170750931 (60 s)
    Quiet time after excitation: 1170750996

2017-02-10

• 11:37am, gate valve closed, pumps off, venting

2017-10-13

• 8:30am, in chamber, balanced
  • S1600492 in bay 1
  • S1600491 in bay 2
  • S1600490 in bay 3
  • S1600489 in bay 4
• 8:34am roughing pump on, clamps on lid
• 8:46am turbo pump on
• Excitations

  • Quiet time before excitation: 1171048567
    Excitation (broad band) at 1171048602 (60 s)
    Quiet time after excitation: 1171048667

  • Quiet time before excitation: 1171049897
    Excitation (broad band) at 1171049933 (60 s)
    Quiet time after excitation: 1171049997

  • Quiet time before excitation: 1171051227
    Excitation (broad band) at 1171051262 (60 s)
    Quiet time after excitation: 1171051327

  • Quiet time before excitation: 1171052557
    Excitation (broad band) at 1171052592 (60 s)
    Quiet time after excitation: 1171052657

  • Quiet time before excitation: 1171053887
    Excitation (broad band) at 1171053922 (60 s)
    Quiet time after excitation: 1171053987

  • Quiet time before excitation: 1171055217
    Excitation (broad band) at 1171055252 (60 s)
    Quiet time after excitation: 1171055317

  • Quiet time before excitation: 1171056547
    Excitation (broad band) at 1171056582 (60 s)
    Quiet time after excitation: 1171056647

  • Quiet time before excitation: 1171057877
    Excitation (broad band) at 1171057912 (60 s)
    Quiet time after excitation: 1171057977

• Chamber opened at about 2:30pm, samples out

This morning I measured the beam profiles at the QPD positions. As expected, the beams are not gaussian there, since we are seeing the interference of the reflections from the two faces of the disks. Nevertheless, the measured sizes are

Here are the images of the beams:

The arm lever lengths (distance from the disk surface to the QPD) can be estimated from the optical drawing:

The optical gain (normalized QPD signal over disk surface angle) is given by

The lasers are behaving well, there is no high noise or wandering lines. The spectrum below is taken in air: that explains the excess of noise in the few kHz region.

I reconfigured the powerstrip and the two Newport controllers to use static IP address in the new 10.10.10.X network, using the workstation as gateway. All scripts updated and working

Removed, since iit was not useful to improve the actuation authority.

This morning Larry set up a network switch to create a local network for the power strip and the two Newport picomotor controllers. The laboratory workstation serves as gateway between the networks.

I still have to configure the power strip and the picomotor controllers to use the new static IP address.

Today I swapped out the 8mW laser and installed two 2.5 mW lasers. I rebuilt the input part of the optical levers and re-aligned everything. See below for a picture of the new setup: red beams are input, yellow beams are output. I also installed a protective screen all around the table, to abvoid any suprios beam to get out.

The high power lasers I tested so far (the Thorlabs 21mW and the JDSU 1125P) are noisy: they both have wandering lines that from time to time are alised down into the base band, destroing the measurement. 

I have three JDSU 1103P units: two of them dlived about 2.5 mW, the third one delivers about 1.4 mW. One of the 2.5mW was installed in the test setup. I swapped it out with the 1.4 mW, so now I have two good 2.5 mW laser. My plan is to modify the new setup to use those two lasers in parallel, splitting each one in two, for a total of four beams of about 1.2 mW each.

The new optical layout is atttached.

2017-02-07

• 10:02am in chamber, balanced
• 10:03am roughing pump on
• 10:30am turbo pump on
• Excitations (they didn't work, I forgot to switch on the noise!!)

  • Quiet time before excitation: 1170548335
    Excitation (broad band) at 1170548367 (60 s)
    Quiet time after excitation: 1170548429

  • Quiet time before excitation: 1170559259
    Excitation (broad band) at 1170559291 (60 s)
    Quiet time after excitation: 1170559353

  • Quiet time before excitation: 1170570183
    Excitation (broad band) at 1170570216 (60 s)
    Quiet time after excitation: 1170570278

  • Quiet time before excitation: 1170581108
    Excitation (broad band) at 1170581140 (60 s)
    Quiet time after excitation: 1170581202

  • Quiet time before excitation: 1170592032
    Excitation (broad band) at 1170592064 (60 s)
    Quiet time after excitation: 1170592126

  • Quiet time before excitation: 1170602956
    Excitation (broad band) at 1170602989 (60 s)
    Quiet time after excitation: 1170603051

• Excitations:

  • Quiet time before excitation: 1170638328
    Excitation (broad band) at 1170638360 (60 s)
    Quiet time after excitation: 1170638422

  • Quiet time before excitation: 1170649252
    Excitation (broad band) at 1170649285 (60 s)
    Quiet time after excitation: 1170649347

  • Quiet time before excitation: 1170660177
    Excitation (broad band) at 1170660209 (60 s)
    Quiet time after excitation: 1170660271

  • Quiet time before excitation: 1170671101
    Excitation (broad band) at 1170671133 (60 s)
    Quiet time after excitation: 1170671195

  • Quiet time before excitation: 1170682025
    Excitation (broad band) at 1170682057 (60 s)
    Quiet time after excitation: 1170682119

2017-02-09

• 4:11pm, pumps off

• In the new chamber
• Excitations:

  • Quiet time before excitation: 1170443490
    Excitation (broad band) at 1170443523 (60 s)
    Quiet time after excitation: 1170443586

  • Quiet time before excitation: 1170454416
    Excitation (broad band) at 1170454449 (60 s)
    Quiet time after excitation: 1170454512

  • Quiet time before excitation: 1170465342
    Excitation (broad band) at 1170465375 (60 s)
    Quiet time after excitation: 1170465438

2017-02-07

• 9:36am gate valve closed, pumps off

The new laser is still acting up a bit, with a wandering line moving sometimes inside the band. Nevertheless, I could perform the first complete measurement of four samples in parallel.

Everything went as expected, there is no visible cross coupling between modes of different disks. The MATLAB code for the analysis is ready and working.

Here are the results:

The Thorlabs laser has been misbehaving for the whole weekend. Even after many days being continuosly on, the wandering line is still moving all over the frequencies.

So this morning I swapped in a JDSU 1125P borrowed from the 40m lab, which provides about 6.8 mW of power. I tested it over the weekend on a separate test table, and after one day or so of operation the power looks reasonably stable. Now it's been on for a few hours: there is still a line moving around, but it's slowing down and hopefully setting down in a good place.

I started a series of test measurements on the samples that were already installed.

• Quiet time before excitation: 1170443490
  Excitation (broad band) at 1170443523 (60 s)
  Quiet time after excitation: 1170443586

2017-02-06

• 8:35am in chamber, balanced
• 8:36am roughing pump on
• 8:50am tubo pump on
• Excitations: (they didn't work, I forgot to switch on the noise!!)

  • Quiet time before excitation: 1170460053
    Excitation (broad band) at 1170460085 (60 s)
    Quiet time after excitation: 1170460147

  • Quiet time before excitation: 1170470977
    Excitation (broad band) at 1170471010 (60 s)
    Quiet time after excitation: 1170471072

  • Quiet time before excitation: 1170481902
    Excitation (broad band) at 1170481935 (60 s)
    Quiet time after excitation: 1170481997

  • Quiet time before excitation: 1170492827
    Excitation (broad band) at 1170492860 (60 s)
    Quiet time after excitation: 1170492922

  • Quiet time before excitation: 1170503752
    Excitation (broad band) at 1170503785 (60 s)
    Quiet time after excitation: 1170503847

  • Quiet time before excitation: 1170514677
    Excitation (broad band) at 1170514710 (60 s)
    Quiet time after excitation: 1170514772

2017-02-07

• 09:36am pumps off

The excitation is working fine. However, there is a large cross coupling in the excitation between channels: so if I switch on only one of the ESD paths, I actually excite all other disks too.  It might be due to the common ground or to the fact that the cables run close to each other. This needs some investigation, but it's not a big issue for the moment being.

On the other hand, the optical levers are very well decoupled: each one sees a different set of modes. So there is no measurable cross coupling between the disks or the readout.

There seems to be something fishy with the Y picomotor of QPD3: it doesn't always move in the same direction for the same set of steps. Some investigations needed here too. Autocentering might fail, but it's still possible to center it manually.

Excitation at 4:56pm (quiet time before excitation 1170032165, quiet time after excitation 1170032234).

Another excitation at 8:30am (2017-02-02) (quiet time before excitation 1170088185, quiet time after excitation 1170088373)

My bad, a cable was disconnected.

The wandering line I mentioned in my previous elog, which is spoiling most of the sensitivity, turns out to be power noise of the laser. 

I used a Thorlabs PDA100 and a SR785 to measure the power noise out of the laser directly, and saw a huge forest of peaks above 20kHz. Among them, a couple of peaks are moving up and down in frequency very fast. The plot below compares two different times of the Thorlabs HNL210L laser (the new one, 21 mW) with the old JTSU laser we are using for the test setup:

The noise of the new laser is cleary much larger (even after the laser has been on for some time) and non stationary. This is a big issue for us. I will contact Thorlabs to inquire if this behavior is normal.

The attached video file shows the peaks dancing around on the SR785 screen.

The autocenter script wasn't working in a very robust way (sometimes the socket connection to the controller failed, some times no motion was obtained after issuing a command). So I rewrote the interface to the Newport controller using the http server interface. The code is in picomotor8742_http.py. This version seems much more robust.

There is a large wandering line that spans all frequencies. Not sure what the origin is, but it will need some noise hunting. Here are spectrograms of all four QPD X signals. The line is visible in all of them, at the same frequency. So it's definitely something external coupling into the light or the QPD electronics. It's not visible in the sum of the QPD quadrants, but maybe just because it's buried in noise.

Finally, I tried to excite the disks, but I couldn't get any motion of the optical lever beams. To be investigated, there might simply be some cables disconnected.

This afternoon we started the pump-down with all the system installed into the chamber. Unfortunately the IGM vacuum gauge isn't working, so we can't be sure what the pressure is. To be fixed

All parts for the motion of the retaining rings have been received and are ok. We're going to clean and bake them. 

I wrote an autocenter script for the four QPD in the new setup (autocenter14.py) and renamed the script for the old chamber (autocenter0.py).

Tested and working properly, with network connection to the picomotor controllers. Be aware that if the picomotor controllers are switched off, their IP address might change.

• checked that the high voltage paths are working:
  • the DAC signal is properly received and amplified by the Trek 2220 HV amplifier
  • the HV switch box is working as expected: I can switch on and off each path individiually using the DAC signals
• installed four samples (refer to the optical drawing for the numbering)
  • S1600472 in bay 1
  • S1600478 in bay 2
  • S1600473 in bay 3
  • S1600480 in bay 4

​

• balanced all samples and centered all optical levers. There is a problem with the fifth connector in the ADC interface board (or maybe with one ADC channel). So one of the quadrants of QPD4 was not working. I moved the connector to number 6 and updated the model. Everything looks fine now.
• the power in the four QPD is quite diverse: this is not unexpected, since it depends on the interference of the reflection from the two surfaces of the disk

• installed the picomotor controllers on the bench, connected them to the net using the switch on the top of the clean room. For the moment being they are using DHCP.
• connected all picomotors to the controllers.
  • Bottom controller, from left to right: QPD1x, QPD1y, QPD2x, QPD2y
  • Top controller, from left to right: QPD3x, QPD3y, QPD4x, QPD4y
• tested the remote control and motion of all picomotors

​