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    Reply  Fri Aug 28 01:08:14 2015, Koji, Electronics, AM Stabilized EOM Driver, RF AM Measurement Unit E1500151 ~ Calibration RFAM_detector_calib.pdfRFAM_detector_calib_spectra.pdf
Worked on the calibration of the RF AM Measurement Unit. 

The calibration concept is as follows:

Generate AM modulated RF output
Measure sideband amplitude using a network anayzer (HP4395A). This gives us the SSB
Entry  Wed Aug 29 11:06:30 2018, Koji, General, General, RF AM RIN and dBc conversion 
0. If you have an RF signal whose waveform is , the amplitude is constant and 1.

1. If the waveform 
    Reply  Wed Jul 22 10:15:14 2015, Koji, Electronics, AM Stabilized EOM Driver, RF test of the EOM/AOM Driver S1500117 
7) Make sure the on/off RF button works,
=> OK

8) Make sure the power output doesn't oscillate,
    Reply  Sat Jul 25 17:24:11 2015, Koji, Electronics, AM Stabilized EOM Driver, RF test of the EOM/AOM Driver S1500117 7x
(Calibration for Attachment 5 corrected Aug 27, 2015)

Now the test procedure fo the unit is written in the document https://dcc.ligo.org/LIGO-T1500404

And the test result of the first unit (S1500117) has also been uploaded to DCC https://dcc.ligo.org/LIGO-S1500117
    Reply  Tue Jul 28 18:36:50 2015, Koji, Electronics, AM Stabilized EOM Driver, RF test of the EOM/AOM Driver S1500117 IMG_20150727_214536773_HDR.jpgEOM_Driver_DAQ_TF_test.pdfEOM_Driver_Mon_PSD.pdf
Final Test Result of S1500117: https://dcc.ligo.org/LIGO-S1500117

After some staring the schematic and checking some TFs, I found that the DAQ channels for MON2 have a mistake in the circuit.
Differential driver U14 and U15 of D0900848 are intended to have the gain of +10 and -10 for the pos and neg outputs.
    Reply  Mon Nov 19 13:33:14 2012, Koji, Optics, Characterization, Resuming testing mirror RoCs Cav_scan_response_zoom_20121016.pdf
In order to resume testing the curvatures of the mirrors, the same mirror as the previous one was tested.
The result looks consistent with the previous measurement.
It seems that there has been some locking offset. Actually, the split peaks in the TF@83MHz indicates 
Entry  Fri Oct 5 03:39:58 2012, Koji, Optics, General, RoC Test setup RoC_test_setup.pdfRoC_test_setup.png
Based on Zach's experiment design, I wrote up a bit more detailed optical layout for the mirror test.
Entry  Fri Jun 29 11:26:04 2012, Zach, Optics, Characterization, RoC measurement setup RoC_measurement_setup.pngRoC_measurement_setup.graffle.zip
Here is the proposed RoC measurement setup. Koji tells me that this is referred to as "Anderson's method".
We would like to use a linear cavity to measure the RoC of the curved mirrors independently (before forming the ring cavity), since the degeneracy
of HOMs will make the fitting easier.
    Reply  Sun Jul 22 15:56:53 2012, Zach, Optics, Characterization, RoC measurement setup detailed_RoC_setup.pngdetailed_RoC_setup.graffle.zip
Here is a more detailed version of the setup, so that we can gather the parts we will need.
Entry  Wed Oct 17 20:36:04 2012, Koji, Optics, General, RoC test cavity locked detailed_RoC_setup.pdfomc_cav_lock_SCRN_SHOT.pngCav_scan_response_20121016.pdf
The RoC test setup has been built on the optical table at ATF.

The cavity formed by actual OMC mirrors have been locked.
Entry  Mon Aug 13 16:59:11 2012, Koji, Clean, General, Room Cleaning Log 
Floor wiped with a wet wiper (Aug 13, 2012)
Floor wiped with a wet wiper (Aug 15, 2012)
Floor wiped with a wet wiper (Sep 25, 2012)
Entry  Tue Jan 22 17:56:32 2013, Koji, Mechanics, General, Rotary stage selection 
Newport UTR80

    Sensitivity: 4 arcsec
    Graduations: 1 deg
    Vernier: 1 arcmin
    Fine travel range: 4 deg
Entry  Thu May 20 17:03:50 2021, Koji, General, General, SRS LCR meter SRS720 borrowed from Downs P_20210520_154841.jpg
Item loan: SRS LCR meter SRS720 borrowed from Downs. The unit is at the 40m right now for testing with an excelitas PD. Once it is done, the setup will
be moved to the OMC lab for testing the high QE PDs
    Reply  Fri Jul 22 17:41:01 2022, Koji, General, General, SRS LCR meter SRS720 returned to Downs PXL_20220723_002330805.jpg
SRS LCR meter SRS720 was returned to Downs as before.

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.
Entry  Mon Apr 22 09:54:21 2019, Joe, General, , Shortening cavity (A5,A14,PZT11,PZT22) to get closer to design FSR CM1_IMG_7699.jpgCM2_IMG_7697.jpg

in units 20um per div on the micrometer [n.b. we reailised that its 10um per div on the micrometer]

CM1 inner screw pos: 11.5
Entry  Thu Nov 8 19:47:55 2012, Koji, Electronics, Configuration, Solder for PZTs 
Rich saids:
I have ordered a small roll of solder for the OMC piezos. 
Entry  Mon Dec 31 03:10:09 2012, Koji, Optics, General, SolidWorks model of the OMC breadboard D1201439_aLIGO_Breadboard_layout_assy_121224.pngD1201439_aLIGO_Breadboard_layout_assy_130105.easm
Entry  Sun Jan 6 23:22:21 2013, Koji, Mechanics, General, SolidWorks model of the OMC suspension  D0900295_AdvLIGO_SUS_Output_Mode_Cleaner_Overall_Assembly.pngD0900295_AdvLIGO_SUS_Output_Mode_Cleaner_Overall_Assembly.easm
Entry  Sat Jul 1 21:33:18 2017, Koji, General, General, Some purchase notes 
- Forgot to close the cylinder valve...

v HEPA prefilter (20"x20"x1" MERV 7)

- Replace the filter for the air conditioning
Entry  Wed Jun 5 18:19:51 2013, Koji, General, General, Some recent photos from the OMC final test at CIT 
Applying First Contact for the optics cleaning
Entry  Mon Jul 21 01:02:43 2014, Koji, Mechanics, Characterization, Some structual mode analysis 6x
Fundamental: 12.3kHz Secondary: 16.9kHz
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  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  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
    Reply  Fri Sep 13 15:09:20 2013, Koji, General, General, Sprinkler installation: done P9134379.jpgP9134378.jpg
A sprinkler head was installed on the HEPA enclosure. The head is covered with a plastic cap.
    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  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  Fri Jun 27 18:51:33 2014, Koji, General, General, Supply 
PTOUCH TAPE (12mm white) x 2
9V batteries
Entry  Fri Oct 9 01:01:01 2020, Koji, General, General, TFT Monitor mounting 20201008214515_IMG_0152.jpg20201008214519_IMG_0153.jpg20201008214536_IMG_0154.jpg20201008220955_IMG_0155.jpg20201008221019_IMG_0156_2.jpg
To spare some room on the optical table, I wanted to mount the two TFT monitor units on the HEPA enclosure frame.
I found some Bosch Rexroth parts (# 3842539840) in the lab, so the bracket was taken for the mount. This swivel head works very well. It's rigid
and still the angle is adjustable.
    Reply  Fri Oct 16 00:53:29 2020, Koji, General, General, TFT Monitor mounting 
The image flipping of the display unit was fixed. The vendor told me how to fix it.

- Open the chassis by the four screws at the side.
- Look at the pass-through PCB board between the mother and display boards.
Entry  Mon Jul 23 17:15:14 2012, Koji, Clean, General, Talking with Margot 
I consulted with Margot about the cleaning of the optics

    Optics are considered as a clean object. Large dusts can be removed by ionized N2 flow etc.
    Barrel of optics can be wiped
with Acetone.
    Optical surfaces are best to be cleaned by First Contact.
    A peek
Entry  Thu Mar 28 03:37:07 2013, Zach, Optics, Configuration, Test setup input optics progress OMC_test_setup_IO.jpg2013-03-27_05.48.20.jpg2013-03-28_02.29.36.jpg
[Lisa, Zach]
Last night (Tuesday), I finished setting up and aligning most of the input optics for the OMC characterization setup. See the diagram below, but
the setup consists of:
Entry  Sun Jul 20 17:20:39 2014, Koji, General, General, The 3rd (LIO) OMC was shipped out to LHO  
The 3rd (LIO) OMC was shipped out to LHO on Friday (Jul 18) Morning.
- All of the on-breadboard cables should be attached and tied down.
Entry  Wed Jul 5 16:59:44 2017, Koji, General, General, The OMC #002 was packed DSC_0360.JPG
[Stephen Koji]

The OMC #002 was packed for the transportation to Downs.

===> And transported to Downs 227 on Jul 6th.
    Reply  Mon Nov 23 23:17:19 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs Q3000_dark_noise_81.pdfQ3000_dark_noise_82.pdfQ3000_dark_noise_83.pdfQ3000_dark_noise_84.pdf
The dark noise levels of the four Q3000 QPDs were measured with FEMTO DLPCA200 low noise transimpedance amp.

The measurement has been done in the audio frequency band. The amp gain was 10^7 V/A. The reverse bias was set to be 5V and the DC output of
the amplifier was ~40mV which corresponds to the dark current of 4nA. It is consistent with the dark current measurement.
    Reply  Tue Nov 24 10:45:07 2020, gautam, Electronics, Characterization, The dark noise of the Q3000 QPDs 
I see that these measurements are done out to 100 kHz - I guess there is no reason to suspect anything at 55 MHz which is where this QPD will be reading
out photocurrent given the low frequency behavior looks fine? The broad feature at ~80 kHz is the usual SR785 feature I guess, IIRC it's got to do
with the display scanning rate.
    Reply  Tue Nov 24 12:27:18 2020, Koji, Electronics, Characterization, The dark noise of the Q3000 QPDs 
The amplifier BW was 400kHz at the gain of 1e7 V/A. And the max BW is 500kHz even at a lower gain. I have to setup something special to see the RF band
dark noise.
With this situation, I stated "the RF dark noise should be characterized by the actual WFS head circuit." in the 40m ELOG.
    Reply  Thu Jul 21 17:47:00 2022, Koji, General, General, The profile of the beam incident on the fiber input coupler fiber_beam_profile.pdf
The profile of the beam incident on the fiber input

The fiber input was deflected by a 45deg mirror. The beam profile was measured with WincamD. The beam was too strong (~60mW) even at the smallest
pump power (ADJ -50) of the NPRO. So the two ND20 filters were added to the lens right before the 45 deg mirror and the camera.
Entry  Tue Jun 28 16:13:34 2022, Koji, General, General, The small optical table not small enough to get out IMG-5203.jpg
The table width was an inch too large compared to the door width. We need to tilt the table and it seemed too much for us. Let's ask the transportation
for handling.

Photo courtesy by Juan
Entry  Wed Jan 2 07:35:55 2013, Koji, Optics, Characterization, Thickness of a curved mirror 
Measured the thickness of a curved mirror:
Took three points separated by 120 degree.
S/N: C2, (0.2478, 0.2477, 0.2477) in inch => (6.294, 6.292, 6.292) in mm
Entry  Tue Dec 10 16:41:51 2013, Koji, General, General, To Buy 
Masks / Wipes => done
Entry  Mon Jul 7 01:36:03 2014, Koji, General, General, To Do 
Optical tests

    Power Budget
    FSR measurement
    TMS measurement (with DC voltage on PZTs)
    PZT DC response
    PZT AC response
    Reply  Thu Jul 10 08:34:57 2014, Koji, General, General, To Do 
Optical tests

    Power Budget
    FSR measurement
    TMS measurement (with DC voltage on PZTs)
    PZT DC response
Entry  Sat Jun 16 08:53:09 2012, Koji, General, General, To Do List 

        Replacing wooden work benches
       W60" x H28-34" x D30" 
Entry  Wed Jun 20 20:37:45 2012, Zach, Optics, Configuration, Topology / parameter selection 8x
EDIT (ZK): All the plots here were generated using my MATLAB
cavity modeling tool, ArbCav
Entry  Fri May 26 21:53:20 2017, Koji, General, Configuration, Trans RF PD setup 
Recent work

- DC output of the trans RF PD was connected to the BNC patch panel. => Now CH4 of the scope is monitoring this signal

- The RF sweep signal from the network analyzer is connected to the power combiner for the EOM drive via the SMA patch panel.
ELOG V3.1.3-