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

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

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

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

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.

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

• Installed in the test chamber CR0
• Excitations:
  • Quiet time before excitation: 1196822477
    Excitation broadband: 1196822509
    Quiet time after excitation: 1196822532
  • Quiet time before excitation: 1196826162
    Excitation broadband: 1196826194
    Quiet time after excitation: 1196826216
  • Quiet time before excitation: 1196829846
    Excitation broadband: 1196829879
    Quiet time after excitation: 1196829901
  • Quiet time before excitation: 1196833531
    Excitation broadband: 1196833563
    Quiet time after excitation: 1196833585
  • Quiet time before excitation: 1196837215
    Excitation broadband: 1196837248
    Quiet time after excitation: 1196837270
  • Quiet time before excitation: 1196840900
    Excitation broadband: 1196840933
    Quiet time after excitation: 1196840955
  • Quiet time before excitation: 1196844585
    Excitation broadband: 1196844617
    Quiet time after excitation: 1196844639
  • Quiet time before excitation: 1196848269
    Excitation broadband: 1196848301
    Quiet time after excitation: 1196848323
     

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

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.

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.

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. 

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 , since fused silica is isotropic it's polarization is proportional to E so . 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.

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.

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.

S1600623

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

S1600624

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

S1600620

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

S1600621

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

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

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

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

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

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

Annealing run (454-459) on 3" wafers - Crime 11/02/2016 https://dcc.ligo.org/LIGO-T1600510

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Will be ready by Friday morning

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

Will be ready by June 28th afternoon

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

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.

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. 

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

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.

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.

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 *
x = loadtxt('predicted_modes.txt')
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()

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

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
• 

2017-06-21

• 4:30 pm- Installed COMSOL, began modeling current ESD by creating parameters and the first arm of the comb

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

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:

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
    Excitation broadband: 1197750228
    Quiet time after excitation: 1197750253
  • Quiet time before excitation: 1197757483
    Excitation broadband: 1197757518
    Quiet time after excitation: 1197757543
  • Quiet time before excitation: 1197764773
    Excitation broadband: 1197764808
    Quiet time after excitation: 1197764833
  • Quiet time before excitation: 1197772063
    Excitation broadband: 1197772098
    Quiet time after excitation: 1197772123
  • Quiet time before excitation: 1197779353
    Excitation broadband: 1197779388
    Quiet time after excitation: 1197779413
  • Quiet time before excitation: 1197786643
    Excitation broadband: 1197786678
    Quiet time after excitation: 1197786703
  • Quiet time before excitation: 1197793933
    Excitation broadband: 1197793969
    Quiet time after excitation: 1197793994
  • Quiet time before excitation: 1197801224
    Excitation broadband: 1197801259
    Quiet time after excitation: 1197801284
     

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
    Excitation broadband: 1198982277
    Quiet time after excitation: 1198982302
  • Quiet time before excitation: 1198989532
    Excitation broadband: 1198989567
    Quiet time after excitation: 1198989592
  • Quiet time before excitation: 1198996822
    Excitation broadband: 1198996857
    Quiet time after excitation: 1198996882
  • Quiet time before excitation: 1199004112
    Excitation broadband: 1199004147
    Quiet time after excitation: 1199004172
  • Quiet time before excitation: 1199011402
    Excitation broadband: 1199011437
    Quiet time after excitation: 1199011462
  • Quiet time before excitation: 1199018692
    Excitation broadband: 1199018727
    Quiet time after excitation: 1199018752
  • Quiet time before excitation: 1199025982
    Excitation broadband: 1199026017
    Quiet time after excitation: 1199026042
     

Polished S1600619 S1600620 S1600621 S1600622

CO2 polishing:

• S1600584
• S1600587
• S1600588: laser tripped near the end, restarted for a second round
• S1600591
• S1600592

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.