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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  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  Thu Apr 17 21:39:25 2014, Koji, Optics, General, More alignment 
STORY:
- The cavity mirrors have scattering spots. The cavity alignment should have been scanned to find a cavity mode to have lowest loss possible. 
  BTW, We only have horizontal dof for the alignment scan.
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  Thu Jun 19 23:16:50 2014, Koji, Optics, General, All of the prisms have been glued P6196525.JPG
- All of the PRISM mirrors have been glued
- 4 out of 5 beam dumps have been glued

TODO
    Reply  Fri Jun 20 18:59:12 2014, Koji, Optics, General, All of the invar blocks have been glued 
All of the INVAR blocks have been glued.
I found thinner shims in the stock.
On Monday, the template will be removed.
    Reply  Mon Jun 23 21:54:16 2014, Koji, Optics, General, All of the gluing completed 
The bottom-side templates were removed.
The last beam dump was removed
TODO
Entry  Sun Jul 6 02:45:56 2014, Koji, Optics, General, FSR Measurement finesse_measurements_log.pdf
3rd OMC FSR / Finesse measurement
RF AM was injected by detuning a HWP.
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  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  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
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 13:42:37 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  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.
Entry  Sun Mar 13 22:02:09 2016, Koji, Optics, Characterization, HQEPD QE measurement (direct comaprison) 
Direct comparison of the PD responsibities

We can expect 5% increase of the QE with the new PD. 


P-pol 10deg incident
Entry  Sat Mar 26 01:49:48 2016, Koji, Optics, Characterization, HQEPD QE QE1.pngQE2.png
Calibration of the transimpedance

Use KEITHLEY 2450 as a calibrated current source. Model 2450 has the current source accuracy of 0.020%+1.5uA at 10mA range. For 6mA current output,
the error is 3uA (0.05%).
Entry  Tue Aug 23 23:36:54 2016, Koji, Optics, Characterization, Inspection of the damaged CM1 (prev H1OMC) 7x
1. Calum and GariLynn checking the CM1 defect from the front side.
2. Same as above
3. Close up of the defect
    Reply  Thu Aug 25 02:17:09 2016, Koji, Optics, Characterization, Inspection of the damaged CM1 (prev H1OMC) 
Initial inspection results by Calum, et al.
https://dcc.ligo.org/LIGO-E1600268
Entry  Fri Sep 9 19:43:32 2016, Koji, Optics, General, D1102211 OMC Diode Mount Glass Block went to Downs 
D1102211 OMC Diode Mount Glass Block (11pcs) have been given to Calum@Downs
Entry  Mon Nov 21 21:19:20 2016, Koji, Optics, General, LWE NPRO Laser / Input Optics / Fiber Coupling 
- About 1.5 month ago, an 700mW LWE NPRO has been brought to OMC Lab.

- The SOP can be found here.

- The base was made for the beam elevation of 3" height. Four 1" pedestals were attached to rise the beam elevation to 4".
    Reply  Wed Dec 7 19:18:10 2016, Koji, Optics, General, LWE NPRO Laser / Input Optics / Fiber Coupling 
FIber Input Mount 132deg
Fiber output mount 275deg
-> 525mW P: 517mW S: 8mW extinction ratio: 0.016
Entry  Tue May 16 19:05:18 2017, Koji, Optics, Configuration, OMC SN002 fix - temporary optics 
Working on the SN002 OMC fix. Checked the inventory. I think I am using C8 mirror as the new temporary CM1 and PZT24 as the new temporary CM2.
Entry  Fri Jun 23 01:58:11 2017, Koji, Optics, General, OMC #002 Repair - CM1 gluing 6x
[Alena, Koji]

Jun 21: Alena and Koji worked on gluing of the CM1 mirror on the OMC breadboard #002. This
is an irregular procedure. Usually, the PZT mirror subassembly is prepared before the mounting prism is glued on the breadboard. In this
Entry  Fri Jun 23 10:55:07 2017, Koji, Optics, General, Dust layer on black glass beam dumps? black_glass_dust.JPG
I wondered why the black glass beam dumps looked not as shiny as before. It was in fact a layer of dusts (or contaminants) accumulated on the surface.
The top part of the internal surface of the black glass was touched by a piece of lens tissue with IPA. The outer surface was already cleaned. IPA
did not work well i.e. Required multiple times of wiping. I tried FirstContact on one of the outer surface and it efficiently worked. So I think the internal
Entry  Sat Jul 1 15:29:57 2017, Koji, Optics, General, Black glass cleaning / Final bonding for the emergency repair for OMC #002 DSC_0347.jpgDSC_0348.jpgDSC_0350.jpgDSC_0352.jpgDSC_0354.jpg
[Alena, Koji] 

Report of the work on June 30.

1. Cleaning of the black glass beam dumps
Entry  Thu Feb 22 20:21:02 2018, Koji, Optics, Characterization, aLIGO EOM test 
POSTED to 40m ELOG
    Reply  Mon Apr 2 17:27:04 2018, Koji, Optics, Characterization, aLIGO EOM test 
2nd optical test http://nodus.ligo.caltech.edu:8080/40m/13725
Entry  Sat May 5 22:51:04 2018, Koji, Optics, General, 3IFO EOM Optical test 
The 3IFO EOM test performed at the 40m. Result: 40m ELOG 13819
Entry  Tue May 15 19:53:45 2018, Koji, Optics, General, EOM Q comparison 
Qs' were estimated with a lorentzian function (eye fit)



Current LHO EOM (final version, modulation depth measurement 2018/4/5)
Entry  Wed May 30 17:44:23 2018, Koji, Optics, Characterization, 3IFO EOM surface check IMG_5756.JPGIMG_5757.JPGIMG_5758.JPGIMG_5759.JPGLooking_at_Hole2.png
3IFO EOM dark microscope images courtesy by GariLynn and Rich

Attachment1/2: Hole #1
Attachment3/4: Hole #2
Entry  Sun Sep 23 19:42:21 2018, Koji, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror reflectivities.pngtransmission.pngphase_diff.pngphase_difference_histogram.png
[Koji Gautam]


With Gautam's help, I ran a coating design code for an HR mirror with the standard quarter-wave design. The design used
here has 17 pairs of lambda/4 layers of SiO2 and Ta2O5 (=34 layers) with the fused silica as the substrate to realize
    Reply  Thu Sep 27 20:19:15 2018, Aaron, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror 
I started some analytic calculations of how OMC mirror motion would add to the noise in the BHD. I want to make some prettier plots, and am adding the
interferometer so I can also compute the noise due to backscatter into the IFO. However, since I've pushed the notebook I wanted to post an update.
Here's
    Reply  Thu Nov 1 19:57:32 2018, Aaron, Optics, General, Montecarlo simulation of the phase difference between P and S pols for a modeled HR mirror 
I'm still not satisfied/done with the solution to this, but this has gone too long without an update and anyway probably someone else will have a
direction to take it that prevents me spinning my wheels on solved or basic questions.

The story will have to wait to be on the elog, but I've put it in the jupyter notebook. Basically:
Entry  Thu Jan 10 20:42:54 2019, Koji, Optics, Characterization, FSR / HOM Test of OMC SN002 
OMC SN002 = Former LHO OMC which CM1 was destroyed by the lock loss pulse in 2016. This OMC needs to be optically tested before storage.

The test items:


[done] FSR measurement with offset PDH locking (FM->AM conversion)
[done] FSR/finesse
Entry  Thu Jan 10 20:45:00 2019, Koji, Optics, Characterization, PZT test cable OMC_PZT_wiring.pdf
As OMC SN002 already has the PZTs connected to the Mighty-Mouse connector, a test cable with a female mighty-mouse connector was made.

A small imperfection: When the cable was inserted to the connector shell, I forgot to mirror the pin out. Therefore the color and pin number
do not match.
Entry  Sat Jan 12 22:49:11 2019, Koji, Optics, Characterization, PM-SM patch cable mode cleaning effect fiber_mode_cleaning.pdf
Mode cleaning capability of an optical fiber was measured. The conclusion is that the
leakage of the non-fiber mode to the fiber output is insignificant and also practically negligible.

The tested fiber was Thorlabs 5-m Polarization Maintaining Single-Mode fiber (P3-1064PM-FC-5, PM Patch Cable, PANDA, 1064 nm, FC/APC, 5m).
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