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  Coating Ring-down Measurement Lab elog, Page 2 of 18  Not logged in ELOG logo
ID Date Author Typedown Category Subject Text Attachments
  26   Wed Jun 29 16:44:17 2016 GabrieleGeneralConfigurationFirst disk eigenfrequencyThe following table shows the lowest eigenfrequency
(Hz) for different sizes of disks

  37   Mon Jul 11 15:21:12 2016 GabrieleGeneralDaily ProgressOne disk installed into the chamber[Alena, Gabriele]

We attached one of the silicon
lenses to a 1" optical post using some
  44   Fri Jul 15 17:56:50 2016 GabrieleGeneralDaily ProgressQPD connected to digital systemI connected the QPD to the ADC interface
with a temporary cable running on the floor.

I could get signals. I still have
  48   Mon Jul 18 14:29:07 2016 GabrieleGeneralDaily ProgressStatus of the test setupI checked that the QPD electronics works
as expected, and that I can acquire the signals
using the ADCs. A new model (x3cr1) is up
  49   Mon Jul 18 17:46:04 2016 GabrieleGeneralDaily ProgressFirst look at QPD signalsHere's the first spectrum of the QPD
X and Y signals, acquired with the digital
system. Roughing and turbo pumps are still
  53   Tue Jul 19 17:21:48 2016 GabrieleGeneralDaily ProgressFirst 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
  56   Thu Jul 21 12:10:14 2016 GabrieleGeneralDaily ProgressGlitch huntingYesterday I could clearly see the glitches
as jumps in the time domain plot of X and
Y signals, and trace them to somewhat harder
  68   Thu Jul 28 14:01:27 2016 AlenaGeneralDaily ProgressClean roomOrdered the clean room (hardware+hepa filters)
and vacuum gauges
  70   Fri Jul 29 14:08:31 2016 GabrieleGeneralDaily ProgressPeak tracking code for real time modelSummary

I wrote a C function
to reconstruct the amlplitude and frequency
of a line. It can be added as a block into
  74   Mon Aug 8 10:42:46 2016 GabrieleGeneralGeneralDependency of eigenmode frequencies on thickness and diameterI ran a set of COMSOL simulations to determine
the dependency of the frequency of each eigenmode
on the disk thickness and diameter, within
  77   Thu Aug 11 08:45:19 2016 GabrieleGeneralGeneralQPD signals with dielectric filterI installed a dielectric laser line filter
(Thorlabs FLH05633-5, center wavelength 633
nm, FWHM 5 nm) in front of the QPD. In this
  82   Sat Aug 13 14:05:02 2016 GabrieleGeneralDaily ProgressFirst work on the measurement user interfaceToday I started programming part of the
user interface that will be used to perform
the measurements. Not much implemented so
  85   Sun Aug 14 18:26:19 2016 GabrieleGeneralGeneralPlans for the automatic mode searchHere's how I imagine the mode search
to proceed:

the user select the list
  92   Sat Aug 20 17:01:10 2016 GabrieleGeneralDaily ProgressFirst ring down measurementsEverything is working pretty well. This
morning the pressure was about 1.2e-6 Torr.
I connected the high voltage amplifier and
  93   Sat Aug 20 22:18:26 2016 GabrieleGeneralDaily ProgressFirst measured QsUsing the first ring down of the day (GPS 1155754513
+ 3600 seconds), I computed the amplitude
of each of the modes already identified,
  94   Sun Aug 21 08:51:22 2016 GabrieleGeneralDaily ProgressNew disk installedVented 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
  96   Sun Aug 21 15:36:16 2016 GabrieleGeneralDaily ProgressNew testRoughing pump stopped at about 3:30:30pm.
HV amplifier on at 3:33:30pm, excitation
at 3:35:30pm. Recentered QPD at 3:36pm
  97   Sun Aug 21 17:16:03 2016 GabrieleGeneralDaily ProgressRing down measurement with new diskAfter fixing the setup, the measurement
with the new disk looks great. After more
than one hour the first two modes are still
  98   Sun Aug 21 17:41:34 2016 GabrieleGeneralDaily ProgressNew testI checked the status at about 5:20pm, the
turbo pump was in error and spinning down,
since the roughing pump has been off for
  99   Mon Aug 22 08:29:24 2016 GabrieleGeneralDaily ProgressNew testRestarted roughing and turbo pump at about

  100   Mon Aug 22 12:01:52 2016 GabrieleGeneralGeneralTests of the dayDisk excited at 12:01pm. Exited the room
at 12:03pm.

Opened the chamber at about 2:30pm,
  102   Tue Aug 23 08:46:04 2016 GabrieleGeneralDaily ProgressDaily testsMO03 - edge polished:

Turbo off, QPD centered, before
excitation (60 seconds)
  103   Tue Aug 23 09:21:25 2016 GabrieleGeneralGeneralStatus of Mark Optics disksWe initially received 20 disks (75 mm diameter,
1 mm thickness) from Mark Optics. Here's
their status as of today
  104   Tue Aug 23 09:44:11 2016 GabrieleGeneralGeneralMeasurements on MO-02Two good ring-downs measurements were performed
on MO-02. The first one was already reported
in a previous elog
  106   Sun Sep 11 10:05:33 2016 GabrieleGeneralDaily ProgressNew substrate in the chamberI installed one of the new substrates (with
flats) into the chamber, and started the
pumpdown at about 9:45am LT.
  107   Mon Sep 12 16:00:06 2016 GabrieleGeneralDaily ProgressFirst fully automated measurements of ring downI finished the first version of the automation
software to measure the ring down of the
disk modes. I tested it with the new substrate
  108   Tue Sep 13 10:33:35 2016 GabrieleGeneralGeneralDisk excitedDisk excited with white uniform noise,
amplitude 5 V, for some tens of seconds.

Excitation off at
  109   Wed Sep 14 13:08:05 2016 GabrieleGeneralGeneralRingdown with roughing pump offAt 1:05pm LT I stopped the roughing pump
and started a ring-down measurement. Pump
restarted at 2:18pm LT.
  110   Wed Sep 14 20:17:33 2016 GabrieleGeneralGeneralBand-limited excitationExcitation started at 20:15:30LT, 20 seconds
long. The excitation is band-limited (10
Hz) centered around each of the predicted
  111   Thu Sep 15 08:13:20 2016 GabrieleGeneralGeneralPump had no effect on ring down measurementsThe plot below shows three measurements
of the Q of the same disk: during the first
two the roughing pump was on, while during
  112   Thu Sep 15 08:27:57 2016 GabrieleGeneralGeneralNew band-limited excitationSame as in elog #110,
but now the amplitude is proportional to
frequency squared:
  114   Thu Sep 15 15:15:10 2016 GabrieleGeneralGeneralEdge effect on lossesI made a COMSOL model that can compute
the distribution of elastic energy for each
mode, dividing it into:
  115   Fri Sep 16 14:06:43 2016 GabrieleGeneralGeneralPump had no effect on ring down measurementsSame plot as below, but this time with
estimated 95% confidence intervals for the
Q values, as obtained from the fit only.
  117   Tue Sep 20 16:12:09 2016 GabrieleGeneralGeneralPump downAs a test, I installed MO1 (the disk with
the burn mark, used for the first edge laser
polishing test) and started pumping down.
  118   Tue Sep 20 16:43:58 2016 GabrieleGeneralGeneralExcitation and ring downThe pressure is at abour 3e-6 Torr. I centered
the QPD and started an excitation. The HV
amplifier manual states that the driver can
  119   Wed Sep 21 08:12:13 2016 GabrieleGeneralGeneralExcitation and ring downNew excitation (2000V) at about 8:06am.
Had to recenter the QPD again after the excitation.

Engaged the 500Hz high pass filter
  120   Wed Sep 21 14:42:47 2016 GabrieleGeneralGeneralSerialized (etched) disk installedJust for fun, I installed the disk thas
has been etched in the center with "1234".
I figured out that the ESD PCB was probably
  121   Thu Sep 22 09:49:21 2016 GabrieleGeneralGeneralRing-down of etched diskQPD centerd, quiet data, light off, one
minute from

PDT: 2016-09-22 09:46:29.393609
  128   Tue Sep 27 08:53:46 2016 GabrieleGeneralVacuumEtched disk installedInstalled the etched disk: using manually
the centering ring allowed me to get the
beam on the QPD. A couple of taps to the
  130   Tue Sep 27 15:10:59 2016 GabrieleGeneralMeasurementsRing-down of etched diskQuiet (roughing pump off, lights off):
60 seconds from
PDT: 2016-09-27 15:05:30.805667 PDT
  131   Wed Sep 28 10:26:58 2016 ranaGeneralGeneralreferences on ideal glassesSome easy to read reviews on
thin films and ideal glass for people getting
started in this Q measuring game.

  133   Mon Oct 17 10:50:50 2016 GabrieleGeneralVacuumNo sign of problems in the electrostatic driveI opened the chamber and took the etched
disk out. Inspection of the electrostatic
drive does not show any sign of burn or damage.
  134   Tue Oct 18 16:29:37 2016 GabrieleGeneralMeasurementsS1600433S1600433, annealing run 10/10/2016


in the measurement system, chamber closed
down started at 4:27pm LT
  135   Tue Oct 18 16:52:16 2016 GabrieleGeneralMeasurementsSample inspections from annealing run 10/10/2016LIGO-T1600466

S1600432 shows some residual
on face, close to the edge, probably from
  136   Wed Oct 19 13:35:23 2016 GabrieleGeneralMeasurementsS1600438S1600438, not annealed, as received
from Mark Optics


pump switched off at 11:42am (2016-10-19)
  137   Wed Oct 19 16:40:24 2016 sults:GeneralMeasurementsS1600349S1600439, not annealed, as received
from Mark Optics


and balanced, pump down started at 4:38pm
  138   Wed Oct 19 17:08:47 2016 GabrieleGeneralMeasurementsS1600433 vs S1600438
S1600433 has been annealed, was
contaminated by the iron oxide, and it was
cleaned using first contact. No residual
  139   Thu Oct 20 11:04:03 2016 GabrieleGeneralMeasurementsSample with flame polished edgesSample with edges flame polished in Glasgow


the chamber and balanced at 11am. Pump down
started at 11:00am.
it looks like
  141   Fri Oct 21 13:45:21 2016 GabrieleGeneralMeasurementsS1600447Sample S1600447, as received from Mark
Optics, second batch


into the chamber, pumping down started at
  142   Fri Oct 21 14:03:17 2016 GabrieleGeneralVacuumRoughing pump movedI moved the roughing pump out of the clean
room, adding an extension hose.

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