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ID Date Author Type Category Subject
648   Mon Apr 1 07:56:01 2019 GabrieleGeneralMeasurements S1600546 S1600551 S1600552 S1600554

2019-04-01

• 7:50am in chamber
• S1600546 in CR1
• S1600551 in CR2
• S1600552 in CR3
• S1600554 in CR4
• 7:55am roughing pump on
• 8:05am turbo pump on
518   Fri Apr 13 10:39:04 2018 GabrieleGeneralMeasurements S1600620 S1600621 S1600623 S1600624

2018-04-13

• 10:37am in chamber
• S1600620 in CR1
• S1600621 in CR2
• S1600623 in CR3
• S1600624 in CR4
• 10:41am roughing pump on
• 10:50am turbo pump on
500   Wed Mar 28 15:46:55 2018 GabrieleGeneralMeasurements S1800611 S1800612 S1800613 S1800614

2018-03-28

• 3:45pm in chamber
• S1800611 in CR1
• S1800612 in CR2
• S1800613 in CR3
• S1800614 in CR4
• 3:47pm roughing pump on
• 3:55pm all pumps fo chamber 0 off, clean air filters off
• 4:00pm turbo pump on
501   Thu Mar 29 09:17:11 2018 GabrieleGeneralMeasurements S1800615 S1800616 S1800617 S1800618

2018-03-29

• 9:15am in chamber
• S1800615 in CR1
• S1800616 in CR2
• S1800617 in CR3
• S1800618 in CR4
• 9:17am roughing pump on
• 9:25am all pumps fo chamber 0 off, clean air filters off
• 9:25am turbo pump on
209   Wed Nov 23 08:55:41 2016 GabrieleGeneralNoise hunting"Advanced" vibration isolation

In normal conditions the RMS of the QPD signals is dominated by the 58 Hz line generated by the roughing pump. Also, when the modes are excited, they exhibit large sidebands at +- 58 Hz that are an annoyance for the analysis.

I improved a bit the level of the 58 Hz in the QPD signals by putting the roughing pump on top of a "Very Useful Box":

Despite the fact that this advanced vibration isolation is already a little bit effective, it might be good to try to build some better suspension and maybe add an acoustic isolation around the pump.

180   Sat Nov 12 09:49:07 2016 GabrieleGeneralMeasurements12 substrates ready for Montreal

The 12 following substrates have been measured and are ready for the first coating experiment in Montreal:

445   Mon Dec 11 08:49:08 2017 Gabriele, Aaron, Brittany, SethGeneralMeasurements50mm / 0.5mm substrate from University Wafers
• Installed in the test chamber CR0
• Excitations:
• Quiet time before excitation: 1196822477
Quiet time after excitation: 1196822532
• Quiet time before excitation: 1196826162
Quiet time after excitation: 1196826216
• Quiet time before excitation: 1196829846
Quiet time after excitation: 1196829901
• Quiet time before excitation: 1196833531
Quiet time after excitation: 1196833585
• Quiet time before excitation: 1196837215
Quiet time after excitation: 1196837270
• Quiet time before excitation: 1196840900
Quiet time after excitation: 1196840955
• Quiet time before excitation: 1196844585
Quiet time after excitation: 1196844639
• Quiet time before excitation: 1196848269
Quiet time after excitation: 1196848323

15   Thu May 19 11:36:04 2016 GabrieleMechanicsDesignA first design of the disk assembly

Here are some screenshots of the disk assembly and a look at how four of them will sit into the vacuum chamber. The Solidworks models are available here: D1600197

Attachment 3: Screen_Shot_2016-05-18_at_3.41.25_PM.png
39   Tue Jul 12 17:19:07 2016 GabrieleElectronicsDaily ProgressADC and DAC cabling

This afternoon I completed the assembly of the electronics boards to interface the ADC and DAC. The ADC is interfaced with a new custom board, which accepts up to eight QPD inputs, the syncronization signal, and it's connected to the ADC:

For the DAC I used one spare board from the Crackle experiment. However, that board had a wrong pinout for the DAC side connector, so I had to implemented again the same hack I did for the crackling noise experiment.

All boards are connected to the ADC and DACs, and to the syncronization signal generated with a SR DS345. No boxes for the moment being, I'll figure out a better organization of the boards in the future if needed. I still haven't tested if the real time system is able to communicate properly with the new interfaces.

207   Tue Nov 22 08:21:35 2016 GabrieleElectronicsCharacterizationADC saturation

Last night measurements didn't work well: even without exciting the modes, the ADC was saturating because of the low frequency signal, particularly a 58 Hz peak:

When the modes were rang up, thing got clearly even worse:

Modification of whitening filter

So I modified the whitening filter, changing C6 from 2.2u to 220nF. The old and new whitening filters are shown below. We have the same amount of whitening at high frequency, but less amplification of the junk at ~50-100 Hz

With this modification, there's no more saturation, even when the modes are excited.

Attachment 1: saturation_1.png
Attachment 2: saturation_2.png

Installed the ADC and DAC boards into a proper box. Also, swapped the temporary DAC board (with cale hack) with the final one. Schematics and PCB are in the DCC: D1600196 and D1600301

The box is sitting on top of the cymac computer, on the back, since I don't have any long cable to connect the ADC.

359   Thu Jun 29 16:40:41 2017 ZachElectronicsModelingAccurate model and force profile

2017-06-29

• I created a much more accurate model of the current ESD setup from the technical drawings. My resulting ESD has dimensions of 21.3x24.3x.1mm with 1 mm spacings and 17.5 mm long electrode arms. The sample has a diameter of 75 mm and thickness of 1mm, the ESD is 1mm below the sample in the current model. I still have to compare the technical drawings to confirm that is the actual distance in the current lab setup.
• I was able to calculate the force profile on the disk from the ESD. COMSOL struggled to resolve the data with a small mesh size over the whole domain, so I created a region of extremely fine mesh around the ESD and the disk and then made the rest of the mesh size normal sized. Over the domain near the ESD my mesh size ranges from 2.5*10-3 to .25 mm and over the rest of the domain it's automatically setup at the normal size.
• The force on a single dipole is given as $F = (P \cdot \nabla)E$, since fused silica is isotropic it's polarization is proportional to E so $F = \chi_e \epsilon_0 \nabla (E^2)$. The electric suscepitibility of fused silica is 1.09, I plotted the profile of the force perpendicular to the plane of the disk and exported data files of the full vector quantity of the force for use with Matlab.

261   Thu Jan 12 10:36:47 2017 GabrieleElectronicsConfigurationAdded ESD bias path to model CR0

I added to the model CR0 an additional bias path for the ESD driver:

Some funny RGC idiosyncrasy: if you have a filter bank named "SUM", you can't add a summation block: if you do you get a name conflict at compilation time. That's why I used a matrix

Updated the MEDM screen accordingly

A quick test shows that working with a bias does not improve the ability to excite the modes. The DAC saturates at +-32k, which corresponds to +-10V out of the ADC, matched to the input range of the HV amplifier. The largest excitation of high frequency modes is obtained by using white noise, no bias, and maximum amplitude.

472   Thu Mar 1 16:25:13 2018 GabrieleGeneralGeneralAging tests

Here's a ongoing summary of the substrate aging tests.

S1600619

Mark Optics with polished edges and CO2 polished, stored in the CR0 vacuum chamber.

2018/03/01 470 LIGO-S1600619-v5
2018/03/03   LIGO-S1600619-v6
2018/03/09   LIGO-S1600619-v7
2018/03/15   LIGO-S1600619-v8
2018/03/24   LIGO-S1600619-v9

S1600623

Mark Optics with polished edges, stored in standard wafer container in the dessicator cabinet

2018/03/01 469 LIGO-S1600623-v4
2018/03/08 480 LIGO-S1600623-v5
2018/03/16 488 LIGO-S1600623-v6

S1600624

Mark Optics with polished edges, stored in standard wafer container in vacuum sealed envelope with dessicant

2018/03/01 469 LIGO-S1600624-v4
2018/03/08 480 LIGO-S1600624-v5
2018/03/16 488 LIGO-S1600624-v6

S1600620

Mark Optics with polished edges and CO2 polished, stored in standard wafer container in the dessicator cabinet

2018/03/03 473

LIGO-S1600620-v5

2018/03/08 480 LIGO-S1600620-v6
2018/03/16 488 LIGO-S1600620-v7

S1600621

Mark Optics with polished edges, stored in standard wafer container in vacuum sealed envelope with dessicant

2018/03/03 473 LIGO-S1600621-v5
2018/03/08 480 LIGO-S1600621-v6
2018/03/16 488 LIGO-S1600621-v7

Attachment 1: S1600619_history.png
Attachment 2: S1600623_history.png
Attachment 3: S1600624_history.png
Attachment 4: S1600620_history.png
Attachment 5: S1600621_history.png
Attachment 6: S1600619_history.png
Attachment 7: S1600623_history.png
Attachment 8: S1600624_history.png
Attachment 9: S1600620_history.png
Attachment 10: S1600621_history.png
Attachment 11: S1600619_history.png
Attachment 12: evolution.png
430   Thu Sep 14 15:59:10 2017 GabrieleFacility All wrapped up for Saturday plumbing work

149   Thu Oct 27 14:02:38 2016 AlenaGeneralGeneralAnnealing

Annealing run (447-448) on 3" wafers - Crime 10/27/2016 https://dcc.ligo.org/T1600485-v1

453   Thu Jan 25 15:33:51 2018 Gabriele, BenGeneralAnnealingAnnealing of 50mm disks

Annealing of 8 fused silica substrates (50mm/0.5mm) started at 3:30pm, January 25th 2018. Standard program: 9 hours ramp up to 900 C, 9 hours hold, 9 hours ramp down

508   Sun Apr 1 10:11:22 2018 GabrieleGeneralGeneralAnnealing on blanks

Started annealing of blank disks: S1600541 S1600542 S1600545 S1600546 S1600551 S1600552 S1600554 S1600555

900C for 9 hours, starting at 10:30am

155   Tue Nov 1 15:34:49 2016 Alena, CalumGeneral Annealing run

Annealing run (449-453) on 3" wafers - Crime 11/01/2016 https://dcc.ligo.org/T1600507

160   Fri Nov 4 16:16:23 2016 AlenaGeneralGeneralAnnealing run

Annealing run (460-465) on 3" wafers - Crime 11/04/2016 https://dcc.ligo.org/T1600513-x0

174   Thu Nov 10 16:07:13 2016 Alena, CalumGeneralGeneralAnnealing run

Annealing run (466-471) on 3" wafers - Crime 11/10/2016

https://dcc.ligo.org/LIGO-T1600524

184   Mon Nov 14 08:54:49 2016 Alena, CalumGeneralGeneralAnnealing run

Annealing run (472-477) on 3" wafers - Crime 11/11/2016 https://dcc.ligo.org/T1600527

489   Sat Mar 24 17:03:57 2018 GabrieleGeneralGeneralAnnealing run

Started annealing of S1600577 S1600580 S1600582 S1600585 at 5pm

ramp up to 600C at 100C/h

hold at 600C for 10 h

ramp down at 100C/h

491   Sun Mar 25 17:10:04 2018 GabrieleGeneralGeneralAnnealing run

Started annealing of S1600579 S1600581 S1600583 S1600586 at 5:00pm

• ramp up to 300 C at 100 C/hour
• hold at 300 C for 5 hours
• ramp down at 100 C/hour
494   Mon Mar 26 16:10:03 2018 GabrieleGeneralGeneralAnnealing run

Started annealing of S1600579 S1600581 S1600583 S1600586 at 5:00pm

• ramp up to 400 C at 100 C/hour
• hold at 400 C for 5 hours
• ramp down at 100 C/hour
496   Tue Mar 27 11:41:06 2018 GabrieleGeneralGeneralAnnealing run

At 11:35am, started annealing of ten fused silica wafers (50.8mm / 0.1 mm) [S1800611 S1800612 S1800613 S1800614 S1800615 S1800616 S1800617 S1800618 S1800619 S1800620]

• ramp up to 900 C at 100 C/h
• hold for 9 h
• ramp down at 100 C/h

Attachment 1: IMG_4259.PNG
499   Wed Mar 28 15:32:07 2018 GabrieleGeneralGeneralAnnealing run

Started annealing of S1600579 S1600581 S1600583 S1600586 at 3:25pm

• ramp up to 500 C at 100 C/hour
• hold at 500 C for 10 hours
• ramp down at 100 C/hour
502   Thu Mar 29 16:15:08 2018 GabrieleGeneralGeneralAnnealing run

Samples S1600519 S1600522 S1600565 S1600566 S1600567 S1600568 S1600569

• ramp up to 500C at 100C/h
• hold at 500C for 10h
• ramp down at 100C/h
506   Sat Mar 31 09:58:56 2018 GabrieleGeneralGeneralAnnealing run

Started annealing of S1600579 S1600581 S1600583 S1600586 at 7:00pm 03/30

• ramp up to 600 C at 100 C/hour
• hold at 600 C for 10 hours
• ramp down at 100 C/hour
263   Wed Jan 18 14:29:16 2017 AlenaGeneralAnnealingAnnealing run (489-490) on 3" wafers - Crime 01/18/2017

Started annealing run Annealing run (489-490) on 3" wafers - Crime 01/18/2017 https://dcc.ligo.org/T1700027 using new hardware

269   Fri Jan 20 16:00:36 2017 AlenaGeneralAnnealingAnnealing run (491-496) on 3" wafers - Crime 01/20/2017

Started Annealing run (491-496) on 3" wafers - Crime 01/20/2017 https://dcc.ligo.org/LIGO-T1700036 Will be done by Monday

350   Wed Jun 21 17:04:20 2017 AlenaGeneralAnnealingAnnealing run (541-542) on 3" wafers - Crime 06/25/2017

Started an annealing run https://dcc.ligo.org/LIGO-T1700271

Will be ready by Friday morning

355   Tue Jun 27 09:20:16 2017 AlenaGeneralAnnealingAnnealing run (546-551) on 3" wafers - Crime 06/27/2017

Started annealing run https://dcc.ligo.org/T1700293

Will be ready by June 28th afternoon

75   Wed Aug 10 09:39:38 2016 GabrieleElectronicsDaily ProgressAnnuntio vobis gaudium magnum: habemus Cymac

Yesterday I cloned the cymac2 disk and installed it into the cymac3.

Jamie tweaked a few things (I can't really give more details) and now cymac3 is up an running with the same software as cymac2.

I compiled and installed the CR1 model, to readout the QPD. No more jumps in the signals!

To be able to access testpoints and have AWG working I had to follow the hack explained here: Cryo_Lab/781

I tested the following features:

• the model is running and signals look good
• I can access test points and DQ channels in real time with both dataviewer and DTT
• I can access old data with dataviewer, using NDS
• awggui is working and I can inject noise, that is properly going to the DAC channel (I check with a scope in the analog world)
• I can upload filters using foton

The plot below shows the spectrum of the QPD. For the moment being I'm just sending a straight HeNe beam into the QPD, since the test setup with the disk is no more available. Units are arbitrary

55   Wed Jul 20 10:26:40 2016 GabrieleElectronicsConfigurationAre glitches a digital artifact?

Not so sure anymore...

• those glitches do not happen at regular times
• I tried to send a sinusoid into another ADC channel, and I couldn't see any jump
• using DTT and zooming into the jumps, they don't seem a clean one-sample jump anymore... There might be a bit of ringing before and/or after the jump
• The jumps have different sizes and directions, and they seems to happen at the same time in all four quadrants, but not in the same direction or with the same amplitude

I was suspecting dust crossing the beam, so I build a very rough enclosure, that should help with dust. I don't think I saw any change in the glitches.

Also:

• glitches are there even with the HeNe off, with ambient light only. So it's not the laser.
• I tried sending a sinusoid into one of the same ADC channels used to acquire the QPD signals. I couldn't see any glitch

So one might conclude that the glictches are produced by the analog QPD electronics. However, I plugged in a scope and I couldn't see any in the analog signal. But I checked only before the DRV135 stages. I'll need some sort of breakout board to test the output of the DRV135.

 Quote: The glitches I saw in the data happens roughly every second, even though not exactly on the second. They are suddend jumps on the signal values over one sample, so of clear digital origin

388   Wed Aug 2 13:47:47 2017 ZachElectronicsModelingArm width Sweep

2017-08-02

• I ran a sweep of the width of the ESD arms. There appears to be a linear relationship across the modes except for mode 25. Mode 25 exhibits a very similar behavior as in the arm gap sweep. I realized that the abrupt change in direction (also noticeable in mode 14) is likely caused by the fact that the force profile is calculated as absolute value, there might be an exponential relationship that gets converted into that shape by the absolute value function.

233   Wed Dec 7 08:48:13 2016 GabrieleElectronicsConfigurationAuto center state written directly to data

I modified the autocenter script. Now while the picomotor is moving, the variable X3:CR1-AUTOCENTER takes the value 1, otherwise it is 0.

283   Tue Jan 31 09:03:12 2017 GabrieleElectronicsConfigurationAuto centering script for the new setup

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.

158   Fri Nov 4 11:31:11 2016 GabrieleElectronicsConfigurationAutocenter control and model modifications

Removed the peak meter lock from the model, since it's not used

Added and EPICS binary bit to control the autocenter, added corresponding buttons to the MEDM screen.

Now the GUI stops the autocentering when acquiring the reference spectrum.

The auto_excite.py also stops the autocentering 35 seconds before the excitation and until 35 second after the excitation, to provide for two reference quiet periods.

110   Wed Sep 14 20:17:33 2016 GabrieleGeneralGeneralBand-limited excitation

Excitation started at 20:15:30LT, 20 seconds long. The excitation is band-limited (10 Hz) centered around each of the predicted mode frequencies. Amplitude inversely proportional to the mode frequency.  The system was quiet before the excitation for many minutes.

For reference, here's the code used for the excitation:

from noise import *
from numpy import *
bands = map(lambda x: [x-5,x+5], x)
ampl = x/x[0]
xx = multi_band_noise(bands, ampl, T=20, fs=65536)

n = AWGNoiseStream(1e-2*xx, channel='X3:CR1-ESD_EXC', rate=65536)
n.start()

132   Thu Sep 29 15:40:45 2016 GabrieleOpticsDesignBeam profile of new 21mW HeNe laser and tweak of optical lever design

I measured the beam profile of the new Thorlabs HeNe (21.8 mW measured). The beam waist is 355 microns, very close to the laser output port.

Using those numbers and the optical gain optimization algorithm, I tweaked the optical lever design. The simplest solution uses two lenses right after the laser to focus the beam down to about 300 microns on the QPD. The arm lever length is about 1.6 m, corresponding to an optical gain of about 18000/rad. I updated the DCC drawing in D1600213

352   Thu Jun 22 15:37:20 2017 ZachElectronicsModelingBeginning modeling

2017-06-22

• Created the geometry of the ESD by creating blocks and joining them with Unions. I then created a block to serve as the domain and added air to that region
• This plot is a combination of a Surface plot of the potential and a Streamline plot of the electric field
• I created another model of the ESD with more accurate measurements to the real thing and added the silica disc to the model
351   Thu Jun 22 13:16:37 2017 ZachElectronicsModelingBeginning with COMSOL

2017-06-21

• 4:30 pm- Installed COMSOL, began modeling current ESD by creating parameters and the first arm of the comb
192   Wed Nov 16 09:43:25 2016 Gabriele, AlastairGeneralDaily ProgressCO2 laser polishing setup

Yesterday we assembled the lase polishing system. The Co2 laser power can be controlled using a waveplate, so we can turn on the laser at maximum power and let it stabilize, before actually turning up the power sent to the disk.

The beam is focused with a 10" focal length lens, and sent to the disk edge, poiting slightly upward to avoid hitting any other part of the disk.

The disk is moved with a combination of a linear and rotation stage, controlled with a MATLAB script. We tuned the translation and rotation speed so that the edge always moves at about 0.5 mm/s. Some refinement of the movimentation procedure will follow.

We tried the setup with one of the damaged samples, and the results are quite good.

More work this afternoon

Attachment 2: 2016-11-15_16.35.14.jpg
198   Thu Nov 17 17:59:44 2016 Gabriele, AlastairGeneralGeneralCO2 laser polishing tests

We improved the control software of the laser polishing system: now the rotation speed is large when the laser is missing the disk because of the flats.

We used S1600479 as a test. This substrate was marked as damaged and had a clear chip. It went thoruhg two different polishing runs

• CO2 power ~19.5 W, speed 0.5 mm/s
• CO2 power ~18.5 W, speed 0.25 mm/s

The second run was probably too slow, and we can see some kind of traces left on the main surface close to the edges

We then laser polished a good subtrate (S1600439) which was already measured before (137) and after annealing (144), with good Q values. This is a substrate from the first batch we received from Mark Optics. The polishing was done at ~ 18W and 0.5 mm/s.

Some pictures below:

448   Tue Dec 19 10:06:04 2017 GabrieleGeneralMeasurementsCO2 polished UW substrates

The four surviving University Wafers 76.2mm/0.5mm wafers have been CO2 polished. They are identified by numbers from 1 to 4 on the container. Number 4 was used for tests, so it might not be as good as the other three. During number3 polishing, the CO2 laser tripped, so I restarted the process from the beginning.

2017-12-19

• 10:10am in chamber
• number 1 in CR1
• number 2 in CR2
• number 3 in CR3
• number 4 in CR4
• 10:15am roughing pump on
• 10:25am turbo pump on
• Excitations
• Quiet time before excitation: 1197750193
Quiet time after excitation: 1197750253
• Quiet time before excitation: 1197757483
Quiet time after excitation: 1197757543
• Quiet time before excitation: 1197764773
Quiet time after excitation: 1197764833
• Quiet time before excitation: 1197772063
Quiet time after excitation: 1197772123
• Quiet time before excitation: 1197779353
Quiet time after excitation: 1197779413
• Quiet time before excitation: 1197786643
Quiet time after excitation: 1197786703
• Quiet time before excitation: 1197793933
Quiet time after excitation: 1197793994
• Quiet time before excitation: 1197801224
Quiet time after excitation: 1197801284

449   Tue Jan 2 15:32:39 2018 GabrieleGeneralMeasurementsCO2 polished UW substrates

2018-01-02

After annealing

• 3:25pm in chamber, as before
• 3:28pm roughing pump on
• 3:40pm turbo pump on
• Excitations:
• Quiet time before excitation: 1198982242
Quiet time after excitation: 1198982302
• Quiet time before excitation: 1198989532
Quiet time after excitation: 1198989592
• Quiet time before excitation: 1198996822
Quiet time after excitation: 1198996882
• Quiet time before excitation: 1199004112
Quiet time after excitation: 1199004172
• Quiet time before excitation: 1199011402
Quiet time after excitation: 1199011462
• Quiet time before excitation: 1199018692
Quiet time after excitation: 1199018752
• Quiet time before excitation: 1199025982
Quiet time after excitation: 1199026042

Quote:

The four surviving University Wafers 76.2mm/0.5mm wafers have been CO2 polished. They are identified by numbers from 1 to 4 on the container. Number 4 was used for tests, so it might not be as good as the other three. During number3 polishing, the CO2 laser tripped, so I restarted the process from the beginning.

2017-12-19

• 10:10am in chamber
• number 1 in CR1
• number 2 in CR2
• number 3 in CR3
• number 4 in CR4
• 10:15am roughing pump on
• 10:25am turbo pump on
• Excitations
• Quiet time before excitation: 1197750193
Quiet time after excitation: 1197750253
• Quiet time before excitation: 1197757483
Quiet time after excitation: 1197757543
• Quiet time before excitation: 1197764773
Quiet time after excitation: 1197764833
• Quiet time before excitation: 1197772063
Quiet time after excitation: 1197772123
• Quiet time before excitation: 1197779353
Quiet time after excitation: 1197779413
• Quiet time before excitation: 1197786643
Quiet time after excitation: 1197786703
• Quiet time before excitation: 1197793933
Quiet time after excitation: 1197793994
• Quiet time before excitation: 1197801224
Quiet time after excitation: 1197801284

467   Tue Feb 27 14:39:21 2018 GabrieleGeneralGeneralCO2 polishing

Polished S1600619 S1600620 S1600621 S1600622

471   Thu Mar 1 13:20:33 2018 GabrieleGeneralGeneralCO2 polishing

CO2 polishing:

• S1600584
• S1600587
• S1600588: laser tripped near the end, restarted for a second round
• S1600591
• S1600592
199   Fri Nov 18 09:27:26 2016 GabrieleGeneralMeasurementsCO2 polishing improves the Q !!

The plot below shows that the Q values of S1600439 improved a lot after the CO2 laser polishing. About 15 modes have Q above 10e6. The first mode at 1kHz has a Q of 37e6, the highest ever measured so far!

Here's a comparison of the Q values of this sample before annealing, after annealing and after CO2 polishing.

ELOG V3.1.3-