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    Reply  Sun Mar 13 21:22:27 2016, Koji, Electronics, Characterization, Dark current measurement of the HQE PD and other PDs 
Transfered for RGA scan

B4 (C1-05) -> F1
C1 (C1-07) -> F2
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  Sat Mar 26 17:39:50 2016, Koji, Electronics, Characterization, HQEPD dark noise PD_dark_current.pdf
Dark noise measurement for 6 HQEPDs and 1 C30665. All of these showed sufficiently low dark current noise levels compared with the noise level of the
DCPD preamp. The measurement was limited by the input noise (ADC) noise of the FFT analyzer as the line noises were too big.

The measurement has been done with the transimpedance of 1e7. The bandwidth of the measurement was 50kHz.
    Reply  Sat Mar 26 18:22:24 2016, Koji, Electronics, Characterization, Baking / Contamination tests of the PDs 
For the production of the aLIGO PDs, the following transfer of the PDs were carried out
A1-23 Cage A1 -> G1
A1-25 Cage A2 -> G2
    Reply  Tue Apr 5 18:22:40 2016, Koji, Electronics, Characterization, Baking / Contamination tests of the PDs QE_after_air_bake.pdf
Possible reduction of the QE was observed after air-bake at 75degC.

Yesterday I received Cage G from Bob for intermediate test of the PD performance after air bake but before vacuum bake.
This cage was prepared to be the production pair.
    Reply  Tue Apr 5 21:20:15 2016, Koji, Electronics, Characterization, More dark noise measurement PD_dark_current.pdf
All survived PDs have been measured.
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.
Entry  Tue Mar 28 21:04:27 2017, Koji, Electronics, Characterization, PDH amp 6x
Attachment 1: PDH amp RF part (before the preamp was installed)

Attachment 2: RF-AF transmission

Attachment 3: Attachment 3: LO dependence
    Reply  Sat Jul 29 18:44:38 2017, rana, Electronics, Characterization, PDH amp 
attachment 6: DCPD preamp looks like the opamp is wired for positive feedback?
    Reply  Sat Jul 29 21:42:51 2017, Koji, Electronics, Characterization, PDH amp 
The polarities indicated in the right circuits were opposite, obviously.
Entry  Thu Feb 22 20:21:02 2018, Koji, Optics, Characterization, aLIGO EOM test 
    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  Wed May 30 16:40:38 2018, Koji, Mechanics, Characterization, EOM mount stability test 
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  Mon Jul 2 11:30:22 2018, Koji, Electronics, Characterization, 3IFO EOM impedance measurement impedance_eom.pdfEOM_Z_DATA.zip
[Rich Koji]

3IFO EOM (before any modification) was tested to measure the impedance of each port.

The impedance plot and the impedance data (triplets of freq, reZ, imZ) were attached to this entry.
Entry  Mon Jul 2 12:29:01 2018, Koji, Electronics, Characterization, Impedances of individual components (3IFO EOM) impedance_coils.pdfimpedance_xtals.pdfq_coils.pdfcomponent_models.pdfliso_models.zip
[Rich Koji]

The impedances of the individual components from the 3IFO EOM (before modification) were tested.
Each component was modeled by LISO. The LISO model (in PDF and txt) are attached at the end of the entry.
Entry  Tue Jul 3 12:07:47 2018, Rich Abbott, Electronics, Characterization, Notes on 3rd IFO EOM EOM_Analysis2.pdf
Attached please see my notes summarizing the models for the electrodes and inductors within the 3rd IFO EOM
    Reply  Wed Jul 4 18:30:51 2018, Koji, Electronics, Characterization, EOM circuit models eom_models.pdfeom9.pdfeom24.pdfeom45.pdf180704_3IFO_EOM_model.zip
The circuit models for the 3IFO EOM (before mods) were made using LISO.
Then the modification plan was made to make it a new LLO EOM.

Impedance data, LISO model, Mathematica files are zipped and attached at the end.
Entry  Thu Jul 26 20:57:07 2018, Koji, Electronics, Characterization, 9MHz port tuned impedance impedance_eom.pdfeom9.pdfeom_models_9MHz.pdf
[Rich Koji]

The 9MHz port was tuned and the impedance was measured.
Entry  Tue Aug 7 15:43:12 2018, Koji, Electronics, Characterization, New LLO EOM stuffed P_20180806_154457.jpgimpedance_eom.pdfimpedance_eom_zoom.pdf
[Rich, Dean, Koji]

Stuffed all inductors for the new LLO EOM. As the impedances were sensitive to the positions of the inductors in the housing, they were glued
with a glue gun.
Entry  Wed Aug 8 17:32:56 2018, Rich Abbott, General, Characterization, Modulation Index Test Setup at 40m Lab 40mLabModIndexSetup.pdf
Attached is a block diagram of the test setup used in the 40m lab to measure the modulation index of the IO modulator
    Reply  Thu Aug 9 11:24:29 2018, Koji, General, Characterization, Modulation Index Test Setup at 40m Lab modulation_depth.pdfmodulation_depth_zoom.pdf
[Rich Koji]

The impedances of the new LLO EOM were measured with the beat note setup at the 40m PSL (as described in the previous ELOG entry.

At the target frequencies (9.1MHz, 24.1MHz, 45.5MHz, 118.3MHz), the modulation responses were (0.09, 2.9e-3, 0.053, 0.021) rad/V.
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).
Entry  Sat Feb 2 16:17:13 2019, Koji, Optics, Characterization, Summary: OMC(001) HOM structure recalculation OMC_HOM_130531.pdfHOM_PZTV.pdfHOM_plot_PZT0_0.pdfCav_scan_response_HOM.pdf
Each peak of the transfer function measurement was fitted again with a complex function:

Entry  Sat Feb 2 20:03:19 2019, Koji, Optics, Characterization, Summary: OMC(002) HOM structure recalculation (before mirror replacement) OMC_HOM_131011.pdfHOM_PZTV.pdfHOM_plot_PZT0_0.pdfCav_scan_response_PZT_HOM.pdf
OMC (002)
History: Measurement date 2013/10/11, Installed to L1 2013/XX
Entry  Sat Feb 2 20:28:21 2019, Koji, Optics, Characterization, Summary: OMC(003) HOM structure recalculation OMC_HOM_140705.pdfHOM_PZTV_PZT1_0V.pdfHOM_plot_PZT0_0.pdfCav_scan_response_PZT_HOM.pdf
OMC (003)
History: Measurement date 2014/7/5, Stored for I1, Installed to H1 2016/8 upon damage on 002
Entry  Sat Feb 2 20:35:02 2019, Koji, Optics, Characterization, Summary: OMC(002) HOM structure recalculation (after mirror replacement)  OMC_HOM_190110.pdfHOM_PZTV.pdfHOM_plot_PZT0_0.pdfCav_scan_response_PZT.pdf
OMC (002) after repair
History:Mirror replacement after the damage at H1. Measurement date 2019/1/10
Entry  Tue Mar 19 17:30:25 2019, Koji, General, Characterization, OMC (002) Test items 
OMC #002 Optical tests

FSR measurement (done, 2019/1/8-9, 2019/4/1)
TMS measurement
(done, 2019/1/9)
TMS measurement (with DC voltage on PZTs) (done, 2019/1/10)
Entry  Thu Mar 28 16:36:52 2019, Koji, Mechanics, Characterization, OMC(002) PZT characterization  PZT_Scan.pdfOMC_PZT_Response.pdf
As performed in the ELOG 202, the PZTs of the OMC 002 were tested.

DC response was measured by sweeping each PZT with 0-150V triangular voltage at 11Hz. Acquire 0.2sec of the tie series using an oscilloscope
to get the PDH error, cavity transmission, and the sweep signal.
Entry  Fri Apr 5 01:07:18 2019, Koji, Optics, Characterization, OMC(002): transmitted beam images CM1trasns.pngCM2trasns.pngFM2trans2.png
There was a concern that the transmission from CM1 has additional fringes. The shape of the transmitted beams from CM1, CM2, and FM2 (main) werecaptured
with WinCamD.
Indeed CM1 and CM2 have the fringes, but it does not exist in the main transmission. So it seems that the fringes are associated with the curved
Entry  Fri Apr 5 01:08:17 2019, Koji, Optics, Characterization, OMC(002): DCPD / QPD alignment IMG_7521.JPGIMG_7529.JPGIMG_7539.JPGIMG_7541.JPG
The beam height in the cavity became totally different from the previous one and the shims needed to be much thicker than before. This is probably because
of the alignment of the newly-glue curved mirror.

As the beam height is 2~2.5mm higher, two shims need to be stacked. The preliminary check of the heights using the alignment disks (dummy PDs)
Entry  Fri Apr 5 20:50:54 2019, Koji, Optics, Characterization, OMC(002): QPD alignment P_20190405_215906.jpgP_20190405_215927.jpg
QPD#              QPD1       QPD2
Housing#          #004       #008
Diode#            #44        #46
Entry  Mon Apr 15 21:11:49 2019, Philip, Optics, Characterization, OMC(004): PZT testing for spare OMC 
[Koji, Philip]

Today we tested the functionality of the four remaining PZTs (11,12,13 and 22) .  Each PZT was placed within a collimated 500um beam.
Roughly half of the beam was blocked by the PZT. The PZT and a PD then acted as shadow sensor. Each PZT was tested with 0 and
    Reply  Tue Apr 16 11:36:36 2019, Koji, Optics, Characterization, OMC(004): PZT testing for spare OMC 9x
Attachment 1: Shadow sensor setup for the PZT displacement test

Attachment 2: PZT endurance test. 4 PZTs were shaken at once.

Attachment 3~5: Function generator setup 100Hz, 3.5Vpp 1.75Voffset (meant be displayed for 50Ohm load)
    Reply  Tue Apr 16 21:16:11 2019, Koji, Optics, Characterization, OMC(004): PZT testing for spare OMC 
After having dug into the past email, it turned out that these wires were the ones already replaced from the original teflonwires. The length of them
were confirmed to be ~19" (480mm). 


Entry  Sat Apr 20 00:50:12 2019, Koji, Optics, Characterization, OMC(004): Spot positions misalignment2.pdfmisalignment3.pdf
Similarly to OMC ELOG 349 the spot positions after the replacement of CM2 were measured
(Attachment 1)
Also, the spot positions after the realignment were measured. (Attachment 2)
Entry  Wed Apr 24 13:58:51 2019, Joe, Optics, Characterization, OMC power budget and UV Epoxy Bonding of BS1 

need to add spot positions.

Mirrors: PZT11,PZT22, A14, A5
Entry  Thu Apr 25 15:05:19 2019, Joe, Optics, Characterization, Looking at PZT HOM spacing dependance and thinking about workflow 
[koji, joe]

The template or glass breadboard was wobbling, and we noticed that the caivty alignment became worse/better when it was pressed down. We saw
that it was the glass breadboard, so it was fixed into the transport fixture more securely. Now its alignement didn't change when it was pressed down.
Entry  Wed May 1 15:40:46 2019, Koji, Optics, Characterization, OMC(004): Spot positions and the scattering misalignment.pdf
Tried a few things.

1. Replaced CM1 (PZT ASSY #10=M21+PZT#22+C12) with PZT ASSY #7 (=M1+PZT#13+C13)

We tried PZT ASSY #7 at the beginning and had the spots at almost at the top edge of the curved mirrors. As we found a particle on the bottom
    Reply  Fri May 3 11:06:28 2019, Koji, Optics, Characterization, OMC(004): Spot positions and the scattering misalignment.pdf
Experiment on 5/1
- CM1 right knob was moved 1div (10um) backward such that the spots were better centered on the mirrors 
FM1 (A5): h=-0.2mm -> 0.4mm made the spot much darker but still it has a few scattering spots.
Entry  Thu May 9 18:10:24 2019, Koji, Optics, Characterization, OMC(004): Spot position scan / power budget 190508.pngscattering_spots_CM1.png
(Now the CCD image is captured as a movie and the screen capture is easier!)

Various spot positions on CM1 and CM2 were tried to test how the transmission is dependent on the spot positions. CM1 has a
few bright spots while CM2 shows very dark scattering most of the case. Attachment 1 is the example images of one of the best alignment
Entry  Thu May 23 01:42:46 2019, Koji, Optics, Characterization, C30665 high power test C30665_high_power_test.pdfpd_surface.jpg
An Excelitas C30665 PD with the cap removed (SN07 in Case H slot #2) was exposed to the beam with the optical power of 1.4mW to 334mW. 
After each illumination, the dark current and the dark noise level were tested. Also the photo image of the PD surface was taken each time.

- No significant change of the dark current after each illumination.
Entry  Thu May 23 23:27:38 2019, Koji, Optics, Characterization, IGHQEX3000 high power test HQEPD_high_power_test.pdfpd_images.png
LaserComponents IGHQEX3000 (Cage B2: Serial# B1-23) was exposed to the beam with the optical power from 1.6mW to 332mW. 
After each illumination, the dark current and the dark noise level were measured. Also the photo image of the PD surface was taken each time.

- No significant change of the dark current after each illumination.
Entry  Mon Jul 1 12:38:49 2019, Koji, Optics, Characterization, A and M prisms perpendicularity measurement 6x
[Stephen, Koji]

The perpendicularity of some of the A and M prisms were tested.

Entry  Mon Jul 1 12:49:42 2019, Koji, Optics, Characterization, Scattering measurement of A and C mirrors omc_cm_tis_062419.pdfomc_prism_tis_062419.pdf
Liyuan's scattering measurement for the A and C mirrors.
    Reply  Thu Aug 22 12:35:53 2019, Stephen, Optics, Characterization, Wedging of the debonded PZTs 2019 August IMG_4775.JPGIMG_4770.JPG
Wedge and thickness measurements of PZTs 12 and 13 took place after debonding and cleaning - results are shown in the first image (handwritten post-it

These thickness measurements seem to have come back thinner than previous measurements. It is possible that I have removed some PZT material
ELOG V3.1.3-