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  Coating Ring-down Measurement Lab elog, Page 4 of 18  Not logged in ELOG logo
ID Date Author Type Categoryup Subject Text Attachments
  284   Tue Jan 31 11:21:44 2017 GabrieleMechanicsDaily ProgressRetaining ring mechanicsAll parts for the motion of the retaining
rings have been received and are ok. We're
going to clean and bake them. 
  286   Tue Jan 31 16:55:17 2017 GabrieleGeneralDaily ProgressImproved autocenter, excitation not working, wandering line The autocenter script wasn't working
in a very robust way (sometimes the socket
connection to the controller failed, some
  288   Wed Feb 1 15:35:30 2017 GabrieleGeneralDaily Progressexcitation not working - FIXEDMy bad, a cable was disconnected.

  291   Mon Feb 6 11:19:13 2017 GabrieleOpticsDaily ProgressLaser swapThe Thorlabs laser has been misbehaving
for the whole weekend. Even after many days
being continuosly on, the wandering line
  295   Tue Feb 7 16:16:37 2017 GabrieleOpticsDaily ProgressLasersThe high power lasers I tested so far (the
Thorlabs 21mW and the JDSU 1125P) are noisy:
they both have wandering lines that from
  296   Wed Feb 8 17:01:01 2017 GabrieleOpticsDaily ProgressTwo laser installed, setup alignedToday I swapped out the 8mW laser
and installed two 2.5 mW lasers. I rebuilt
the input part of the optical levers and
  300   Thu Feb 9 09:30:52 2017 GabrieleOpticsDaily ProgressTwo laser installed, setup alignedThe lasers are behaving well, there is
no high noise or wandering lines. The spectrum
below is taken in air: that explains the
  303   Fri Feb 10 17:16:28 2017 GabrieleMechanicsDaily ProgressTranslation stage to move retaining ringsThis afternoon I installed the picomotor
and the translation stage that will be used
to move the retaining rings up and down.
  304   Sat Feb 11 16:22:26 2017 GabrieleMechanicsDaily ProgressTranslation stage to move retaining ringsThe ring motion up and down was not very
smooth, again due to friction on the centering
  305   Tue Feb 14 10:55:13 2017 GabrieleGeneralDaily ProgressSomething fishy with bay 4 of the new setupI did two set of measurements with the
new coated samples from Montreal. I reshuffled
the position in the two measurements. In
  311   Fri Feb 17 13:44:47 2017 GabrieleOpticsDaily ProgressSwapped picomotor and re-alignmentSince I had recurrent problems with the
picomotors used for QPD3, I swapped them
with another Newport motorized mirror that
  331   Fri Mar 10 16:44:13 2017 GabrieleOpticsDaily ProgressUpdated in vacuum periscope of CR0This afternoon I removed the old periscope
from CR0 and installed a new one with finely
adjustable mount, like those in the new chamber.
  338   Fri Apr 7 16:19:03 2017 GabrieleOpticsDaily ProgressNew 1103P laser installedThis afternoon I installed the new Lumentum
(former JDSU) HeNe laser, model 1103P in
  11   Fri May 6 14:20:43 2016 GabrieleElectronicsDesignDesign of optical lever electronics For the optical levers we are going to
use the same QPD that are used in aLIGO optical
levers (see T1600085 and 
  12   Sun May 8 13:35:04 2016 ranaElectronicsDesignDesign of optical lever electronics Koji, Rich, and I recently came up with
a new QPD design which is better for general
lab use than the aLIGO ones (which have a
  13   Tue May 10 13:32:17 2016 GabrieleElectronicsDesignDesign of optical lever electronics After a very useful discussion with Rich
this morning, I think the circuit based on
aLIGO optical levers design should be good
  14   Thu May 19 11:33:44 2016 GabrieleElectronicsDesignOptical lever electronics designThe circuit design sent out for fabrication
is available in the DCC: D1600196
  15   Thu May 19 11:36:04 2016 GabrieleMechanicsDesignA first design of the disk assemblyHere are some screenshots of the disk assembly
and a look at how four of them will sit into
the vacuum chamber. The Solidworks models
  16   Fri May 20 15:18:58 2016 GabrieleOpticsDesignOptical levers layoutAttached a first layout of the optical
lever systems. The beam spot radius on the
QPD is about 0.8 mm, and the lever arm length
  17   Sun May 22 23:40:45 2016 GabrieleOpticsDesignOptical levers layoutAn improved design is attached. I modified
the input telescope to avoid using shor focal
length lenses, to make it less critical,
  18   Thu May 26 02:51:27 2016 GabrieleElectronicsDesignESD designA preliminary design of the ESD board is
available on the DCC: D1600214
  132   Thu Sep 29 15:40:45 2016 GabrieleOpticsDesignBeam profile of new 21mW HeNe laser and tweak of optical lever designI measured the beam profile of the new
Thorlabs HeNe (21.8 mW measured). The beam
waist is 355 microns, very close to the laser
  266   Thu Jan 19 14:16:53 2017 GabrieleMechanicsDesignNew concept for retaining ring motionSince my experiment with coil and magnets
didn't work out very well, here's
a new concept for the motion of the four
  20   Mon Jun 6 13:35:36 2016 GabrieleElectronicsGeneralComponentsThe PCBs for the QPD circuit and ADC interface
are here and look ok. All electronics components
are also here (except for the ADC connector
  21   Tue Jun 7 14:07:55 2016 GabrieleFacilityGeneralRack and workstationI moved the unused rack from the Crackling
Noise lab to the C.Ri.Me lab. It will be
used for the new cymac. I also started putting
  57   Thu Jul 21 14:58:26 2016 GabrieleElectronicsGeneralGlitches are of digital originSo here's the final proof that the
glitches I see are digital:

There is a positive jump
  63   Wed Jul 27 08:59:12 2016 GabrieleElectronicsGeneralPressure now in torrThe 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.
  65   Wed Jul 27 11:27:11 2016 GabrieleFacilityGeneralPumps stopped and venting11:25am LT: closed valve between roughing
and turbo pumps, switched off both pumps.
Turbo pump is slowing down
  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
  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
  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,
  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
  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:
  113   Thu Sep 15 11:23:13 2016 GabrieleFacilityGeneralChamber openTurbo pump off and spinning down at 9:37am
LT. Pumo completely stopped at 11:15am LT

Openend the chamber and removed
  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
  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.

  149   Thu Oct 27 14:02:38 2016 AlenaGeneralGeneralAnnealingAnnealing run (447-448) on 3" wafers
- Crime 10/27/2016 https://dcc.ligo.org/T1600485-v1

  157   Fri Nov 4 08:13:25 2016 GabrieleElectronicsGeneralPower outage?This morning I found the cymac and the
workstation rebooted, so I suspected a power
cut in the last days. However, the function
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