 Wed Apr 3 17:39:38 2013, Koji, Mechanics, Characterization, Calibration of the test PZTs before the glue test 
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We want to make sure the responses of the PZT actuator does not change after the EP30-2 gluing.
A shadow sensor set up was quickly set-up at the fiber output. It turned out the ring PZTs are something really not-so-straightforward.
If the PZT was free or just was loosely attached on a plane by double-sided tape, the actuation response was quite low (30% of the spec). |
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Thu Apr 4 01:35:04 2013, Koji, Optics, Characterization, Mode matching to the OMC cavity
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The fiber output was matched with the lenses on a small bread board.
The detailed configuration is found in the following elog link.
http://nodus.ligo.caltech.edu:8080/OMC_Lab/105 |
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Thu Apr 4 01:43:06 2013, Koji, Optics, Characterization, Mirror T measurement
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[Zach, Koji]
The measurement setup for the transmission measurement has been made at the output of the fiber.
- First, we looked at the fiber output with a PBS. It wasn't P-pol so we rotated the ourput coupler. |
 Fri Apr 5 14:39:26 2013, Koji, Mechanics, Characterization, Calibration of the test PZTs after the heat cure
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We attached fused silica windows on the test PZTs. http://nodus.ligo.caltech.edu:8080/OMC_Lab/93
The glued assemblies were brought to Bob's bake lab for the heat cure. There they are exposed to 94degC heat for two hours (excluding ramp up/down
time). |
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Mon Apr 8 11:11:37 2013, Koji, Optics, Characterization, More Mirror T measurement
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More Ts of the mirrors were measured.
A mirror specification:
Request: 8300+/-800 ppm |
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Mon Apr 8 11:29:08 2013, Koji, Optics, Characterization, Mirror/PZT Characterization links
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Mirror List
http://nodus.ligo.caltech.edu:8080/OMC_Lab/152
Mirror T measurement: |
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Mon Apr 8 11:49:18 2013, Koji, Mechanics, Characterization, PZT actuator tested at LLO
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Test result of the PZTs by Valera and Ryan
PZT Length Angle
# [nm/V] [urad/um]
11 14.5 17.6
12 13.8 17.8
13 11.2 25.0
14 14.5 6.6
15 12.5 10.6
21 14.5 9.7
22 13.8 28.8
23 14.5 6.8 ==> Assembly #2
24 18.5 51.7 ==> Used for prototyping
25 17.1 13.8
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Fri Apr 12 09:25:31 2013, Koji, Optics, Characterization, Alignment of the OMC (without glue)
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[Zach Koji]
The first attempt not to touch the curved mirrors did not work. (Not surprising)
The eigenmode is not found on the mirror surface. |
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Tue Apr 16 08:12:14 2013, Koji, Optics, Characterization, Further More Mirror T measurement
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T&Rs of the B mirrors and some of the E mirrors are measured.
I found that these BSs have high loss (1%~3%) . As this loss will impact the performance of
the squeezer |
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Tue Apr 16 23:26:51 2013, Koji, Optics, Characterization, Further More Mirror T measurement
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Since the previous measurement showed too high loss, the optical setup was checked.
It seemed that a PBS right before the T&R measurement setup was creating a lot of scattering (halo) visible with a sensor card.
This PBS was placed to confirm the output polarization from the fiber, so it was ok to remove it. |
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Mon May 6 19:31:51 2013, Koji, Optics, Characterization, Spot position measurement on the diode mounts
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Measurement Order: DCPD2->DCPD1->QPD1->QPD2
DCPD1: 1.50mm+0.085mm => Beam 0.027mm too low
DCPD2: 1.75mm+0.085mm => Beam 0.051mm too high (...less confident) |
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Wed May 8 15:08:57 2013, Koji, Optics, Characterization, Spot position measurement on the diode mounts
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Remeasured the spot positions:
DCPD1: 1.50mm+0.085mm => Beam 0.084mm too high
DCPD2: 1.50mm+0.085mm => Beam 0.023mm too high |
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Mon May 13 14:49:35 2013, Koji, Mechanics, Characterization, Mounting Glass Bracket still broke with tightenin stress
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[Koji / Jeff]
This is the elog about the work on May 9th.
We made two glass brackets glue on the junk 2" mirrors with the UV glue a while ago when we used the UV bonding last time. |
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Fri May 31 14:07:54 2013, Koji, Optics, Characterization, Transverse Mode Spacing measurement afte the baking
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Measurement for pitch
Free Spectral Range (FSR): 264.9703 +/− 0.0007 MHz
Cavity roundtrip length: 1.131419 +/− 0.000003 m |
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Wed Jun 5 01:06:35 2013, Zach, General, Characterization, L1 OMC as-built diagram
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D1300507
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Tue Jun 18 10:01:11 2013, Koji, Optics, Characterization, Cavity Finesse analysis
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This is the analysis of the cavity finesse data taken on Apr/13/2013 (before baking), May/30/2013 (after baking), and Jun/02/2013 (after cleaning).
If we believe this result, baking contaminated the cavity, and the first contact removed it. That agrees with the power measurement of the transmitted
light. |
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Sat Jul 6 17:10:07 2013, Koji, Mechanics, Characterization, PZT Response analysis
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Analysis of the PZT scan / TF data taken on May 31st and Jun 1st.
[DC scan]
Each PZT was shaken with 10Vpp 1Hz triangular voltage to the thorlabs amp. |
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Wed Aug 21 08:31:21 2013, Koji, Optics, Characterization, H1 OMC cavity alignment
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Alignment of the H1 OMC cavity mirrors
- The cavity mirrors as well as the first steering mirror were aligned on the cavity side template.
- The locking of the cavity was not so stable as before. Some high freq (several hundreds Hz) disturbance makes the cavity |
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Tue Aug 27 17:02:31 2013, Koji, Mechanics, Characterization, Spot position measurement on the diode mounts
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After the PZT test, the curved mirrors were aligned to the cavity again.
In order to check the height of the cavity beam, the test DCPD mount was assembled with 2mm shim (D1201467-3)
The spot position was checked with a CCD camera. |
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Thu Aug 29 02:52:50 2013, Koji, Optics, Characterization, H1OMC Curved Mirror Alignment
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Cavity parameter was measured with 50V bias on PZT1 (CM1)
- PZT combination was changed: PZT1 #21 (PZT ASSY#6) / PZT2 #25 (PZT ASSY #4)
- 19th HOMs of the USB makes accidental resonance with the nominal cavity length. |
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Fri Aug 30 12:24:28 2013, Koji, Optics, Characterization, H1OMC Spot positions
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Beam heights on the diodes
DCPD1: 14.459mm -> With 1.5mm shim, the beam will be 0.038mm too low. |
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Mon Oct 14 13:40:16 2013, Koji, Optics, Characterization, H1 OMC Optical testing
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Since the middle of September, the optical tests of H1 OMC were took place.
Here is summary of the progress.
TEST1: FSR/FINESSE measurement before applying First Contact |
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Mon Oct 14 15:50:55 2013, Koji, Optics, Characterization, H1 OMC Power budget
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LHO OMC power budget
Date
2013/9/17
2013/9/17
2013/10/16
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Tue Oct 15 18:50:08 2013, Koji, Optics, Characterization, QPD alignment
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1) Deburr the bottom surfaces of the QPD housings
2) Aligned the QPDs
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Wed Oct 16 19:16:29 2013, Koji, Optics, Characterization, PD alignment
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shim 1.5mm 001/002 |
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Mon Mar 3 02:46:21 2014, Koji, General, Characterization, Spot positions scanned
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Spot positions on CM1 and CM2 scanned according to the recipes provided by the previous entry.
The best result obtained was:
Transmission from FM2: 32.7mW |
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Tue Mar 25 17:10:10 2014, Koji, Optics, Characterization, OMC spot position estimation
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| Spot positions were inferred from the photos |
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Mon May 12 22:43:02 2014, Koji, Optics, Characterization, Measured FSR/TSM of the OMC cavity
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Data analysis of the FSR/TSM measruement last week.
1. FSR was measured with "the golden arches" technique.
FSR = 263.0686 MHz +/- 900Hz |
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Wed May 14 02:15:15 2014, Koji, Optics, Characterization, FSR/TSM adjustment of the OMC cavity
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1. FSR was adjusted and measured with "the golden arches" technique again.
FSR = 264.8412 MHz +/- 1400Hz => Lcav = 1.13197 m. (nominal 1.132m)
2. Transverse mode spacings for the vertical and horizontal modes were measured. |
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Fri May 16 00:13:36 2014, Koji, Optics, Characterization, Cavity mirror gluing part 1
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BS1/FM1/FM2 for I1OMC were glued.
FM1 had to be intentionally rotated.
FM1 had to be intentionally shifted to avoid scattering spot. |
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Sat May 17 07:40:14 2014, Koji, Optics, Characterization, I1OMC cavity mirrors glued
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I1OMC cavity mirrors were glued.
FSR = 264.82MHz => Lcav = 1.132m (nominal 1.132m)
TMS/FSR for Vpzt1=Vpzt2=0: 0.2185 (V) and 0.2196 (H) (nominal 0.219) |
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Sun Jul 6 02:46:20 2014, Koji, Optics, Characterization, OMC power budget
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3rd OMC power budget (2014/7/2)
Input power: 34.8mW
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Sun Jul 6 03:56:40 2014, Koji, Optics, Characterization, HOM measurement with PZT vol swept
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| Cavity FSR/TMS measurement (2014/7/5) with PZT voltages swept from 0V to 200V (50V step) |
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Sun Jul 6 08:31:14 2014, Koji, Optics, Characterization, HOM measurement with PZT vol swept
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3rd OMC, HOM diagram at PZT1=0V and PZT2=50V.
First coincidence with the carrier is the 32nd-order carrier mode. Very good. |
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Tue Jul 8 18:54:54 2014, Koji, Mechanics, Characterization, PZT characterization
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Each PZT was swept with 0-150V 11Hz triangular wave.
Time series data for 0.2sec was recorded for each PZT.
The swept voltage at the resonances were extracted and the fringe number was counted. |
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Thu Jul 10 23:22:28 2014, Koji, Optics, Characterization, I1OMC QPD
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QPD# QPD1 QPD2
Housing# #006 #007
Diode# #50 #51 |
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Fri Jul 11 00:06:33 2014, Koji, Optics, Characterization, I1OMC PD
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DCPD# DCPD1 DCPD2
Housing# #009 #010
Diode# #07 #10 |
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Sun Jul 13 17:46:28 2014, Koji, Optics, Characterization, OMC backscatter measurement
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Backscattering reflectivity of the 3rdOMC was measured.
Attached: Measurement setup
1) A CVI 45P 50:50 BS was inserted in the input beam path. This BS was tilted from the nominal 45 deg so that the reflection of the input beam |
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Tue Jul 15 03:00:42 2014, Koji, Optics, Characterization, OMC backscatter measurement
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Presence of the misaligned SRM (T=20%) was forgotten in the previous entry.
This effectively reduces the OMC reflectivity by factor of 25.
This is now reflected in the original entry. Also the argument about the power spectram density was modified. |
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Tue Jul 15 03:34:16 2014, Koji, Optics, Characterization, OMC backscatter measurement
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Backscatter measurement ~ 2nd round
Summary
- The backscatter reflectivity of the 3rd OMC is 0.71 ppm |
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Thu Jul 17 02:19:20 2014, Koji, Mechanics, Characterization, I1OMC vibration test 6x
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Summary
- The breadboard has a resonance at 1.2kHz. The resonant freq may be chagned depending on the additional mass and the boundary condition.
- There is no forest of resonances at around 1kHz. A couple of resonances It mainly starts at 5kHz. |
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Sun Jul 20 17:19:50 2014, Koji, Mechanics, Characterization, I1OMC vibration test ~ 2nd round 9x
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Improved vibration measurement of the OMC
Improvement
- Added some vibration isolation. Four 1/2" rubber legs were added between the OMC bread board and the transport fixture (via Al foils). |
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Mon Jul 21 01:02:43 2014, Koji, Mechanics, Characterization, Some structual mode analysis 6x
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Prisms
Fundamental: 12.3kHz Secondary: 16.9kHz
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Wed Aug 27 23:13:13 2014, Koji, Optics, Characterization, Collection of the power budgetting info
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L1 OMC Cavity power budget
H1 OMC Cavity power budget
3IFO OMC Cavity power budget |
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Tue Sep 9 20:59:19 2014, Koji, Mechanics, Characterization, Structural mode analysis for the PZT mirror 6x
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Structural analysis of the PZT mirror with COMSOL.
Inline figures: Eigenmodes which involves large motion of the tombstone. In deed 10kHz mode is not the resonance of the PZT-mirror joint,
but the resonance of the tombstone. |
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Tue Sep 8 11:18:10 2015, Koji, Optics, Characterization, PBS Transmission measurement
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Motivation: Characterize the loss of the Calcite Brewster PBS.
Setup: (Attachment 1)
- The beam polarization is rotated by an HWP |
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Wed Sep 9 01:58:34 2015, Koji, Optics, Characterization, PBS Transmission measurement
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Calcite Brewster PBS Continued
The transmission loss of the Calcite brewster PBS (eLIGO squeezer OFI) was measured with different conditions.
The measured loss was 3600+/-200ppm. (i.e. 900+/-50 ppm per surface) |
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Thu Sep 10 04:03:42 2015, Koji, Optics, Characterization, More polarizer optics measurement (Summary)
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Brewster calcite PBS (eLIGO Squeezer OFI)
Loss L = 3600 +/- 200ppm
Angular dependence: Attachment 1 |
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Wed Sep 23 17:49:50 2015, Koji, Optics, Characterization, More polarizer optics measurement (Summary)
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For the Glasgow PBS, the measurement has been repeated with different size of beams.
In each case, the PBS crystal was located at around the waist of the beam.
Otherwise, the measurement has been done with the same way as the previous entries. |
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Tue Dec 15 13:38:34 2015, Koji, Electronics, Characterization, EOM Driver linearity check
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Linearity of the EOM driver was tested. This test has been done on Nov 10, 2015.
- Attachment 1: Output power vs requested power. The output start to deviate from the request above 22dBm request.
- Attachment 2: Ctrl and Bias voltages vs requested power. This bias was measured with the out-of-loop channel. |