 Mon Aug 22 16:59:13 2016, Gabriele, Alastair, Optics, Daily Progress, Laser polishing of the disk edges 
|
We set up a test facility for laser polishing the disk edges, using the CO2 laser in the TCS laboratory. We focused the beam with a 10" focal length
lens, and installed the disk on a "rotation stage" that we motorized with a hand drill. We used a HeNe optical lever and a small container
with water to define the horizontal plane and adjusted the disk as well as we could. |
|
Mon Aug 22 12:01:52 2016, Gabriele, General, General, Tests of the day
|
Disk excited at 12:01pm. Exited the room at 12:03pm.
Opened the chamber at about 2:30pm, got the disk out for edge polishing, installed it back at 3:30pm, pumping down at 3:40pm.
Stopped the roughing pump at 4:44:00pm (+60 seconds clean data, GPS 1155944657). Switched on the HV amplifier, excitation at 4:47:30pm. Recentered |
|
Sun Aug 21 15:36:16 2016, Gabriele, General, Daily Progress, New test
|
| Roughing pump stopped at about 3:30:30pm. HV amplifier on at 3:33:30pm, excitation at 3:35:30pm. Recentered QPD at 3:36pm |
 Sun Aug 21 17:41:34 2016, Gabriele, General, Daily Progress, New test
|
I checked the status at about 5:20pm, the turbo pump was in error and spinning down, since the roughing pump has been off for about 1.5 hours.
I let the pump switch off.
|
|
Mon Aug 22 08:29:24 2016, Gabriele, General, Daily Progress, New test
|
Restarted roughing and turbo pump at about 8:10am.
Quote:
I checked the status |
|
Sun Aug 21 17:16:03 2016, Gabriele, General, Daily Progress, Ring down measurement with new disk 22x
|
After fixing the setup, the measurement with the new disk looks great. After more than one hour the first two modes are still ringing down, meaning that
the Q's are larger than 10 millions.
Here's the comparison of the spectrum before and after the excitation, with the identified modes: |
|
Sun Aug 21 13:45:56 2016, Gabriele, Optics, Daily Progress, Wierd behavior of ring downs and Improved setup
|
The last two ring downs I measured today showed a weird behavior of the lowest modes:
|
|
Sun Aug 21 08:51:22 2016, Gabriele, General, Daily Progress, New disk installed
|
Vented the chamber. Installed a new disk (MO 03). The one I measured yesterday is now named MO 02 and it is the one with the "burnt mark" from
the previous experiment (due to the electrostatic drive).
Startep roughing pump at 8:50am. Started turbo pump at 9.00am. |
|
Sat Aug 20 22:18:26 2016, Gabriele, General, Daily Progress, First measured Qs 22x
|
Using the first ring down of the day (GPS 1155754513 + 3600 seconds), I computed the amplitude of each of the modes already identified, using a
short FFT spectrogram (each FFT is 1 second long, overlap of 0.5 s).
Then I used the same code I developed at LMA to fit the ring down, including the beat between the unresolved mode pairs. The fit is versy sensitive |
|
Sat Aug 20 17:01:10 2016, Gabriele, General, Daily Progress, First ring down measurements
|
Everything is working pretty well. This morning the pressure was about 1.2e-6 Torr. I connected the high voltage amplifier and I could drive the disk
without problems.
I measured the beam shape and size at the QPD. We have about 50 uW, we see a TEM01-like mode due to the interference of the two disk surfaces |
|
Fri Aug 19 19:05:01 2016, Gabriele, Optics, Daily Progress, Disk installed into the chamber 10x
|
I assembled the disk suspension sytem and installed into the chamber. Although I don't have the magnets and coils, I installed the movable retaining
disk, and used it to center the disk.
|
|
Fri Aug 19 13:46:55 2016, Alena, Calum, Jon, Liz, Steve, Gabriele, Facility, Daily Progress, Clean room and vacuum complete
|
This morning we installed the clean room curtains and washed them. It turns out that the air filters are supposed to be powered at 277V (?) instead of
115V. So right now the flux is quite low. We are looking into the problem: either replace them with 115V modules or install a small transformer.
We also installed the vacuum chamber on the table and connected all the pumps and gauges. There are no leaks and we could pump down easily the |
|
Thu Aug 18 18:15:18 2016, Gabriele, Alena, Clean, Daily Progress, Clean room construction progress
|
Ceiling, back and side panels are installed. The air filters have been cabled and connected to the power supply.
|
|
Wed Aug 17 16:41:05 2016, Gabriele, Alena, Clean, Daily Progress, Clean room construction progress
|
The clean room frame is built and secured to the floor and wall. Panels are being installed on the ceiling and back. Also, the optical table has been
leveled.
|
|
Tue Aug 16 11:57:03 2016, Gabriele, Electronics, Configuration, Fixed cymac3 network and time issue
|
The cymac3 internal clock was off by about 10 seconds. When I tried to start the NTP service, I found out that the cymac3 couldn't reach any external
server. It turned out that the gateway in /etc/network/interfaces was set to the wrong address. I fixed it and rebooted. Now NTP is working and the
time is correct. |
|
Tue Aug 16 11:53:30 2016, Alena, Gabriele, Clean, Daily Progress, Clean room progress
|
Some progress on the cleam room: bar fixed to the wall, some more structure built, filters in place. We had to (literally) work around a corner of the
low ceiling that we haven't noticed before. More contruction will follow tomorrow. We also had to order some additional parts (more extrusions, brackets,
screws, etc...) |
|
Sun Aug 14 18:26:19 2016, Gabriele, General, General, Plans for the automatic mode search
|
Here's how I imagine the mode search to proceed:
the user select the list of nominal frequencies and the frequency range for the search
the automation creates an excitation
which is a sum of band-limited white noise, centered around each of the modes, with the desired bandwidth. The excitation is normalized to match a reasonable |
|
Sun Aug 14 18:13:52 2016, Gabriele, Electronics, Daily Progress, Progress on the user interface
|
Some progress on writing the user interface:
Now the user can open a file that defines the nominal mode frequencies (from COMSOL simulations) and select which modes to search for: |
|
Sun Aug 14 11:40:29 2016, Gabriele, Electronics, Daily Progress, Some python code
|
Today I wrote some auxiliary functions that will be useful for the measurement system:
noise.py: set of functions to generate band-limited noise (using inverse FFT) and multiple band noise. Using the awg python interface
I can also start and stop the noise injection. Some examples of the result: |
|
Sat Aug 13 14:05:02 2016, Gabriele, General, Daily Progress, First work on the measurement user interface
|
Today I started programming part of the user interface that will be used to perform the measurements. Not much implemented so far, but you can get an
idea of the look:
|
|
Sat Aug 13 11:17:17 2016, Gabriele, Facility, Daily Progress, Spot the differences
|
|
|
Fri Aug 12 10:33:14 2016, Gabriele, Electronics, Configuration, Storage added to cymac3
|
Installed two new 2TB disks into the cymac3. Also, the main disk has a 1TB partition with the operating system, so I created a new 1TB partition. I created
a logic volume that spans the three partitions, for a total of about 5TB. This partition is mounted in /mnt/data and linked to the /frames folder. Frames
are written to this new logic volume. |
|
Thu Aug 11 10:59:39 2016, Gabriele, Electronics, Configuration, Quadrant calibration
|
I cross checked the calibration of the sum channel with a power meter. Now all quadnant signals X3:Q?_OUT and the sum signal X3:CR1-SUM_OUT are
correctly calibrated in microwatts. |
|
Thu Aug 11 09:10:01 2016, Gabriele, Electronics, Configuration, Real time model
|
Compiled and installed an updated real time model. It acquires the four QPD segments, compute sum and differences, and normalize. I also added three
experimental peak tracking components, that will be used to track in real time the amplitude and frequency of the disk modes.
|
|
Thu Aug 11 08:45:19 2016, Gabriele, General, General, QPD signals with dielectric filter
|
I installed a dielectric laser line filter (Thorlabs FLH05633-5, center wavelength 633 nm, FWHM 5 nm) in front of the QPD. In this way we are no more
affected by the room light. In the plot below blue is without filter, red with filter. A lot of peaks at high frequency are eliminated by the filter.
|
|
Wed Aug 10 10:04:35 2016, Gabriele, Mechanics, Daily Progress, The prototype of the disk retain system is here 6x
|
Yesterday we received the prototype of the disk suspension and retain system. Everything looks good. I checked that the disk fits in the holder, and
all dimensions are good. The coil holders are out for winding, so I couldn't test the movimentation yet.
|
|
Wed Aug 10 09:39:38 2016, Gabriele, Electronics, Daily Progress, Annuntio 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! |
|
Mon Aug 8 10:42:46 2016, Gabriele, General, General, Dependency of eigenmode frequencies on thickness and diameter 26x
|
I ran a set of COMSOL simulations to determine the dependency of the frequency of each eigenmode on the disk thickness and diameter, within the tolerances.
I chose wide ranges: diameter 75.0 +- 0.1 mm and thickness 1.0 +- 0.1 mm, much more than the expected tolerances. It turns out that the frequencies depends
almost exactly linearly on both variables: mostly on the thickness and negligibly on the diameter. The following plots shows: the mode shape and frequency (left), |
|
Tue Aug 2 16:00:32 2016, Gabriele, Electronics, Characterization, More on the signal jumps
|
So I’m sending a 1.123 Hz sinusoid into the ADC, and generating 3.123
Hz sines and cosines in the model. Frequencies are reasonably incommensurable with one second.
The plots below shows all three signals. In the top panels, I just separate |
|
Tue Aug 2 15:58:12 2016, Gabriele, Electronics, Daily Progress, Six QPD functional and tested
|
I finished populating the new four QPD boards, and fixed the first one I populated weeks ago. I tested all five new boards: the output of the transimpendance
respond correctly to the ambient light; the output of the whitening also respond correctly and has increased high frequency noise; the differential driver
stages are all functional and balanced. |
|
Mon Aug 1 16:56:57 2016, Gabriele, Electronics, Daily Progress, Populated four new QPD boards
|
| Today I populated four more QPD boards. All components are installed, except for the QPD themselves. |
|
Fri Jul 29 14:08:31 2016, Gabriele, General, Daily Progress, Peak tracking code for real time model
|
Summary
I wrote a C function to reconstruct the amlplitude and frequency of a line. It can be added as a block into a real time monitor.
The idea is to use it to track in real time the frequency and amplitude of the disk modes, during the ring down. I did some tests and finally managed to
get the function to compile and run on the cymac2 (the crackling lab cymac). |
|
Thu Jul 28 17:15:22 2016, Gabriele, Electronics, Daily Progress, ADC/DAC interfaces upgrade
|
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. |
|
Thu Jul 28 14:01:27 2016, Alena, General, Daily Progress, Clean room
|
| Ordered the clean room (hardware+hepa filters) and vacuum gauges |
|
Thu Jul 28 13:58:48 2016, Alena, Gabriele, Clean, Daily Progress, The old chamber is now being cleaned and baked
|
| Cleaned the chamber in the washing machine at 40m and started 48 baking at 120 C |
|
Wed Jul 27 15:43:02 2016, Gabriele, Facility, Daily Progress, Vacuum chamber dismantled and ready for cleaning
|
[Alena, Gabriele]
As decided at out Red Door meeting, we're going to clean the vacuum chamber and move it to the large table, which will be enclosed in a clean
room. |
|
Wed Jul 27 11:27:11 2016, Gabriele, Facility, General, Pumps stopped and venting
|
11:25am LT: closed valve between roughing and turbo pumps, switched off both pumps. Turbo pump is slowing down
After lunch I opened the chamber and removed everything from the inside.
The chamber around the vacuum gauge is really dirty now, see picture: |
|
Wed Jul 27 10:19:36 2016, Gabriele, Electronics, Configuration, Last finding in the signal jump saga
|
This plot shows a signal which is generated purely digitally inside a code that I was testing.
Jumps are present even in this case.
|
|
Wed Jul 27 08:59:12 2016, Gabriele, Electronics, General, Pressure now in torr
|
The old channel X3:CR1-PRESSURE_LOGTORR does not exist anymore. The new channel is now directly in torr and it is called X3:CR1-PRESSURE_TORR.
I had to write a C function to compute the 10^x operation, since it is not included in the RCG routines. Also it's not possible to include
library functions, so I had to write an ad-hoc function, which first compute the integer part of the exponent, and then approximate the fractional part |
|
Mon Jul 25 17:44:13 2016, Gabriele, Electronics, Characterization, High frequency noise budget
|
I measured the noise sources limiting the QPD sensitivity. Unfortunately, I had to do some MATLAB tricks to get rid of the glitches: basically I load
the data directly from the raw frames (NDS access to data is not working yet) and remove all jumps in the signals that happen in one single sample and
are larger than a manually tuned threshold. This is not perfect, but it's enough to give us a rough idea of the spectrum of the QPD signal. The following |
|
Tue Jul 26 11:45:03 2016, Gabriele, Electronics, Characterization, High frequency noise budget
|
Just to confirm that my noise estimates make sense, here's a plot of the not-normalized QPD signal that gives the X motion (sum and difference of
all four quadrants):
|
|
Mon Jul 25 15:35:31 2016, Gabriele, Optics, Characterization, Calibration of the QPD in physical units
|
The equations below are wrong. Please refer to https://nodus.ligo.caltech.edu:8081/CRIME_Lab/116
for the correct results
I measured the properties of the beam on the QPD. The total power is 31 uW. The beam shape is not gaussian,
since we are seeing the interference of the reflection from the two surfaces: |
|
Mon Jul 25 12:24:06 2016, Gabriele, Electronics, Configuration, More on the signal jumps
|
Here are two more tests I did this morning
removed the DAC card from the cymac and the models, and restarted everything: signal jumps are still there
move the cymac2
from the crackling noise lab to the CRIME lab, ans set it up with all the same hardware I was using with the cymac3: there are no jumps, signals look perfect |
|
Fri Jul 22 14:22:10 2016, Gabriele, Electronics, Configuration, Investigations on the signal jumps
|
[Rolf, Ben, Rich, Gabriele]
Rolf couldn't find any good explanation on the software side for the signals jumps. He investigated a bit the reason why IOP takes a long
execution time, without success. It's still mysterious why it ran with low time for a while. |
|
Thu Jul 21 14:58:26 2016, Gabriele, Electronics, General, Glitches are of digital origin
|
So here's the final proof that the glitches I see are digital:
There is a positive jump (of random size) every second, every time 0.45s after the beginning of the second. There is a negative jump
at a less constant time, but between 0.65s and 0.8s after the beginning of each second
I moved my whole setup to the crackle lab. This included: |
|
Thu Jul 21 12:10:14 2016, Gabriele, General, Daily Progress, Glitch hunting
|
Yesterday I could clearly see the glitches as jumps in the time domain plot of X and Y signals, and trace them to somewhat harder to see jumps in the
quadrant signals.
I tried to catch them with an oscilloscope looking at the analog signals, but couldn't see any. However, for a brief period I had |
|
Tue Jul 19 20:19:38 2016, Gabriele, Electronics, Configuration, Glitches are a digital artifact
|
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
|
|
Wed Jul 20 10:26:40 2016, Gabriele, Electronics, Configuration, Are 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 |
|
Tue Jul 19 17:21:48 2016, Gabriele, General, Daily Progress, First modes excited!
|
We can't generate any arbitary signal with the real time model, since awg is not working properly yet. For the moment being I added a uniform random
number generator in the model (only option I found for noise) and send it into the ESD filter bank. In this way I can generate band-passed noise.
I plugged in the DAC output to the HV amplifier input, and I could send white noise to the electrostatic drive. Behold: I was able to excite |
|
Tue Jul 19 17:15:37 2016, Gabriele, Facility, Daily Progress, Vacuum pressure acquired
|
[Alena, Gabriele]
We connected the analog output of the vacuum gauge controller to one of the ADC channels. The signal is calibrated so that the pressure is 10^(X3:CR1-PRESSURE_LOGTORR_OUT).
Unfortunately the RTG does not know how to compute 10^x... |
|
Mon Jul 18 18:05:46 2016, Gabriele, Optics, Daily Progress, Optical setup
|
Small modifications to the optical setup:
added a 1m focal lenght lens (AR coated for 1064nm...) right before the beam enters the viewport, to reduce the beam spot size on the
QPD
added a 0.3 ND right after the laser, to avoid saturation of the QPD (about 75 microwatts total on the QPD)
|
|
Mon Jul 18 17:48:58 2016, Gabriele, Electronics, Configuration, Status of real time system and workstation
|
[EricQ, Gabriele]
The real time system seems to be working properly, except for the excitations: we can't activate any excitation using awggui or diaggui
Eric rebuilt the workstation from scratch installing Debian 8.5. All CDS software seem to be working. We setup a ssh-key for ssh'ing into |
|
Mon Jul 18 17:46:04 2016, Gabriele, General, Daily Progress, First look at QPD signals
|
Here's the first spectrum of the QPD X and Y signals, acquired with the digital system. Roughing and turbo pumps are still on.
The noise floor seems quite non stationary. To be investigated.
|
|
Mon Jul 18 14:29:07 2016, Gabriele, General, Daily Progress, Status of the test setup
|
I checked that the QPD electronics works as expected, and that I can acquire the signals using the ADCs. A new model (x3cr1) is up and running. It acquires
the four quadrants, convert them from counts to volts, and compensate for the analog whitening filter. The four quadrant signals are X3:CR1-Q1_OUT, X3:CR1-Q2_OUT,
X3:CR1-Q3_OUT, X3:CR1-Q4_OUT. |