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    Reply  Mon Apr 8 11:11:37 2013, Koji, Optics, Characterization, More Mirror T measurement 
More Ts of the mirrors were measured.
A mirror specification:
Request: 8300+/-800 ppm
Entry  Mon Apr 8 11:29:08 2013, Koji, Optics, Characterization, Mirror/PZT Characterization links 

    Mirror List
    http://nodus.ligo.caltech.edu:8080/OMC_Lab/152
     
    Mirror T measurement:
Entry  Mon Apr 8 11:49:18 2013, Koji, Mechanics, Characterization, PZT actuator tested at LLO 
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
Entry  Fri Apr 12 09:25:31 2013, Koji, Optics, Characterization, Alignment of the OMC (without glue) 
[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.
    Reply  Tue Apr 16 08:12:14 2013, Koji, Optics, Characterization, Further More Mirror T measurement 
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
    Reply  Tue Apr 16 23:26:51 2013, Koji, Optics, Characterization, Further More Mirror T measurement 
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.
Entry  Mon May 6 19:31:51 2013, Koji, Optics, Characterization, Spot position measurement on the diode mounts DCPD1.pngDCPD2.pngQPD1.pngQPD2.png
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)
    Reply  Wed May 8 15:08:57 2013, Koji, Optics, Characterization, Spot position measurement on the diode mounts DCPD1.pngDCPD2.pngQPD1.pngQPD2.png
Remeasured the spot positions:
DCPD1: 1.50mm+0.085mm => Beam 0.084mm too high
DCPD2: 1.50mm+0.085mm => Beam 0.023mm too high
Entry  Mon May 13 14:49:35 2013, Koji, Mechanics, Characterization, Mounting Glass Bracket still broke with tightenin stress 
[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.
Entry  Fri May 31 14:07:54 2013, Koji, Optics, Characterization, Transverse Mode Spacing measurement afte the baking  Cav_scan_response_130530_Pitch.pdfCav_scan_response_130530_Yaw.pdf
Measurement for pitch
Free Spectral Range (FSR): 264.9703 +/− 0.0007 MHz
Cavity roundtrip length: 1.131419 +/− 0.000003 m
Entry  Wed Jun 5 01:06:35 2013, Zach, General, Characterization, L1 OMC as-built diagram L1OMC_asbuilt.pdf
 D1300507
 
Entry  Tue Jun 18 10:01:11 2013, Koji, Optics, Characterization, Cavity Finesse analysis finesse_measurements.pdf
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.
Entry  Sat Jul 6 17:10:07 2013, Koji, Mechanics, Characterization, PZT Response analysis PZT_Scan.pdfL1OMC_PZT_Response.pdf
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.
Entry  Wed Aug 21 08:31:21 2013, Koji, Optics, Characterization, H1 OMC cavity alignment 
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
Entry  Tue Aug 27 17:02:31 2013, Koji, Mechanics, Characterization, Spot position measurement on the diode mounts DCPD1.png
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.
Entry  Thu Aug 29 02:52:50 2013, Koji, Optics, Characterization, H1OMC Curved Mirror Alignment Cav_scan_response_130828_Pitch.pdfCav_scan_response_130828_Yaw.pdf
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.
Entry  Fri Aug 30 12:24:28 2013, Koji, Optics, Characterization, H1OMC Spot positions DCPD1.pngDCPD2.pngQPD1.pngQPD2.png
Beam heights on the diodes

DCPD1: 14.459mm -> With 1.5mm shim, the beam will be 0.038mm too low.
Entry  Mon Oct 14 13:40:16 2013, Koji, Optics, Characterization, H1 OMC Optical testing 
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 
Entry  Mon Oct 14 15:50:55 2013, Koji, Optics, Characterization, H1 OMC Power budget OMC_power_budget.pdf
LHO OMC power budget

    
        
            Date

           2013/9/17
            2013/9/17
            2013/10/16
Entry  Tue Oct 15 18:50:08 2013, Koji, Optics, Characterization, QPD alignment 
1) Deburr the bottom surfaces of the QPD housings
2) Aligned the QPDs
 
    Reply  Wed Oct 16 19:16:29 2013, Koji, Optics, Characterization, PD alignment 
 
 shim 1.5mm 001/002
Entry  Mon Mar 3 02:46:21 2014, Koji, General, Characterization, Spot positions scanned 
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
Entry  Tue Mar 25 17:10:10 2014, Koji, Optics, Characterization, OMC spot position estimation OMC_spot.pdf
Spot positions were inferred from the photos
Entry  Mon May 12 22:43:02 2014, Koji, Optics, Characterization, Measured FSR/TSM of the OMC cavity Cav_scan_response_Pitch.pdfCav_scan_response_Yaw.pdf
Data analysis of the FSR/TSM measruement last week.
1. FSR was measured with "the golden arches" technique.
FSR = 263.0686 MHz +/- 900Hz
Entry  Wed May 14 02:15:15 2014, Koji, Optics, Characterization, FSR/TSM adjustment of the OMC cavity  Cav_scan_response_140503_Pitch.pdfCav_scan_response_140503_Yaw.pdf
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.
Entry  Fri May 16 00:13:36 2014, Koji, Optics, Characterization, Cavity mirror gluing part 1 
BS1/FM1/FM2 for I1OMC were glued.
FM1 had to be intentionally rotated.
FM1 had to be intentionally shifted to avoid scattering spot.
Entry  Sat May 17 07:40:14 2014, Koji, Optics, Characterization, I1OMC cavity mirrors glued Cav_scan_response_140516_Pitch.pdfCav_scan_response_140516_Yaw.pdf
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)
Entry  Sun Jul 6 02:46:20 2014, Koji, Optics, Characterization, OMC power budget 
3rd OMC power budget (2014/7/2)
Input power: 34.8mW
Entry  Sun Jul 6 03:56:40 2014, Koji, Optics, Characterization, HOM measurement with PZT vol swept Cav_scan_response_PZT1.pdfCav_scan_response_PZT2.pdfOMC_HOM_140705.pdf
Cavity FSR/TMS measurement (2014/7/5) with PZT voltages swept from 0V to 200V (50V step)
    Reply  Sun Jul 6 08:31:14 2014, Koji, Optics, Characterization, HOM measurement with PZT vol swept HOM_plot.pdf
3rd OMC, HOM diagram at PZT1=0V and PZT2=50V.
First coincidence with the carrier is the 32nd-order carrier mode. Very good.
Entry  Tue Jul 8 18:54:54 2014, Koji, Mechanics, Characterization, PZT characterization PZT_Scan.pdfI1OMC_PZT_Response.pdf
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.
Entry  Thu Jul 10 23:22:28 2014, Koji, Optics, Characterization, I1OMC QPD 
QPD#              QPD1       QPD2
Housing#          #006       #007
Diode#            #50        #51
Entry  Fri Jul 11 00:06:33 2014, Koji, Optics, Characterization, I1OMC PD 
DCPD#             DCPD1      DCPD2
Housing#          #009       #010
Diode#            #07        #10
Entry  Sun Jul 13 17:46:28 2014, Koji, Optics, Characterization, OMC backscatter measurement OMC_backscatter.pdf
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
    Reply  Tue Jul 15 03:00:42 2014, Koji, Optics, Characterization, OMC backscatter measurement 
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.
    Reply  Tue Jul 15 03:34:16 2014, Koji, Optics, Characterization, OMC backscatter measurement OMC_backscatter.pdfOMC_backscatter.png
Backscatter measurement ~ 2nd round


Summary

- The backscatter reflectivity of the 3rd OMC is 0.71 ppm
Entry  Thu Jul 17 02:19:20 2014, Koji, Mechanics, Characterization, I1OMC vibration test 6x
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.
    Reply  Sun Jul 20 17:19:50 2014, Koji, Mechanics, Characterization, I1OMC vibration test ~ 2nd round 9x
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).
Entry  Mon Jul 21 01:02:43 2014, Koji, Mechanics, Characterization, Some structual mode analysis 6x
Prisms
Fundamental: 12.3kHz Secondary: 16.9kHz
Entry  Wed Aug 27 23:13:13 2014, Koji, Optics, Characterization, Collection of the power budgetting info 
L1 OMC Cavity power budget
H1 OMC Cavity power budget
3IFO OMC Cavity power budget
    Reply  Tue Sep 9 20:59:19 2014, Koji, Mechanics, Characterization, Structural mode analysis for the PZT mirror 6x
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.
Entry  Tue Sep 8 11:18:10 2015, Koji, Optics, Characterization, PBS Transmission measurement setup.JPGCaF2Prism.jpgCaF2Prism2.JPG
Motivation: Characterize the loss of the Calcite Brewster PBS.

Setup: (Attachment 1)

- The beam polarization is rotated by an HWP
    Reply  Wed Sep 9 01:58:34 2015, Koji, Optics, Characterization, PBS Transmission measurement 
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)
    Reply  Thu Sep 10 04:03:42 2015, Koji, Optics, Characterization, More polarizer optics measurement (Summary) eLIGO_PBS.pdfHWP.pdfTFP.pdfGlasgow_PBS.pdf
Brewster calcite PBS (eLIGO Squeezer OFI)

Loss L = 3600 +/- 200ppm
Angular dependence: Attachment 1
    Reply  Wed Sep 23 17:49:50 2015, Koji, Optics, Characterization, More polarizer optics measurement (Summary) Glasgow_PBS_spotsize.pdf
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.
Entry  Tue Dec 15 13:38:34 2015, Koji, Electronics, Characterization, EOM Driver linearity check Output_linearity.pdfCtrl_Bias.pdf
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.
Entry  Tue Dec 15 13:39:13 2015, Koji, Electronics, Characterization, Phase noise measurement of aLIGO EOM drivers phase_noise.pdfphase_noise_9MHz.pdf
This measurement has been done on Dec 1st, 2015.


The phase noise added by the EOM driver was tested.

The test setup is depicted in the attached PDF. The phase of the RF detector was set so that the output is close to zero crossing as much as
Entry  Tue Dec 15 13:42:37 2015, Koji, Optics, Characterization, Dimensions / packaging of HQE PDs PC147842.jpgPC147846.jpgPC147848.jpgHQEPD_dimension.pdf
The dimensions of a high QE PDs was measured as well as the ones for C30665. (Attachment 4, Unit in mm)
They seemed to be very much compatible.


The PDs came with the designated case (Attachment 1). The bottom of the case has a spongy (presumably
Entry  Sat Feb 20 19:11:22 2016, Koji, Electronics, Characterization, Dark current measurement of the HQE PD and other PDs P2197992.jpgPD_dark_current.pdfPD_dark_current_others.pdf
Dark current of the HQE PD and other PDs were measured.

- The HQE PDs were loaded on the new PD transportation cages (Attachment 1)
The PDs are always shorted by a clean PD plugs. The PD element is still capped with Kapton seals.
Entry  Sun Mar 6 02:13:28 2016, Koji, Optics, Characterization, PD glass reflections P3048124.JPGP3048125.JPG
On friday, I removed a glass cover of a G30655 with a PD can cutter.

When a beam shoots a Perkin Elmer/Excelitas PD, we usually observe three reflections.
We always wonder what these are.
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