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Entry  Mon Dec 31 03:11:45 2012, Koji, Optics, Characterization, Further more RoC measurement Cav_scan_response_zoom_20121125_C6_9.pdf
Total (excluding C2, C7, C8): 2.575 +/- 0.005 [m]
New results
C6: RoC: 2.57321 +/− 4.2e-05m    
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  Wed Jan 2 07:45:39 2013, Koji, Optics, Characterization, First Contact test Cav_scan_response_zoom_20121125_C2_before.pdfCav_scan_response_zoom_20121125_C2_after.pdf
Conclusion: Good. First contact did not damage the coating surface, and reduced the loss

- Construct a cavity with A1 and C2
- Measure the transmission and FWHM (of TEM10 mode)
Entry  Thu Jan 10 18:37:50 2013, Koji, Optics, Characterization, Wedging of the PZTs PZT_wedging.pdf
Yesterday I measured the thickness of the PZTs in order to get an idea how much the PZTs are wedged.
For each PZT, the thickness at six points along the ring was measured with a micrometer gauge. 
The orientation of the PZT was recognized by the wire direction and a black marking to indicate the polarity.
Entry  Wed Jan 16 14:10:50 2013, Koji, Optics, Characterization, Autocollimator tests of optics perpendicularity/parallelism 
The items:
- Autocollimator (AC) borrowed from Mike Smith (Nippon Kogaku model 305, phi=2.76", 67.8mm)
- Retroreflector (corner cube)
Entry  Fri Jan 18 13:25:17 2013, Koji, Optics, Configuration, Autocollimator calibration autocollimator_calibration.pdf
An autocollimator (AC) should show (0,0) if a retroreflector is placed in front of the AC.
However, the AC may have an offset. Also the retroreflector may not reflect the beam back with an exact parallelism.
To calibrate these two errors, the autocollimator is calibrated. The retroreflector was rotated by 0, 90, 180, 270 deg
Entry  Sat Jan 19 20:47:41 2013, Koji, Optics, Characterization, Wedge measurement with the autocollimator autocollimator_wedge_measurement.pdf
The wedge angle of the prism "A1" was measured with the autocollimator (AC).
The range of the AC is 40 arcmin. This means that the mirror tilt of 40arcmin can be measured with this AC.
This is just barely enough to detect the front side reflection and the back side reflection.
Entry  Mon Feb 4 00:39:08 2013, Koji, Optics, Characterization, Wedge measurement with the autocollimator and the rotation stage autocollimator_wedge_measurement.pdf
Method:

    Mount the tombstone prism on the prism mount. The mount is fixed on the rotation stage.
    Locate the prism in front of the
autocollimator.
    Find the retroreflected reticle in the view. Adjust the focus if necessary.
    Confirm that the rotation of the
    Reply  Wed Feb 6 02:34:10 2013, Koji, Optics, Characterization, Wedge measurement with the autocollimator and the rotation stage 
Measurement:

    A6:   α = 0.665 deg, β = +3.0 arcmin (1.5 div up)
    A7:   α = 0.635 deg, β =  
0.0 arcmin (0.0 div up)
    A8:   α = 0.623 deg, β = - 0.4 arcmin (-0.2 div up)
    A9:   α =
Entry  Thu Feb 7 23:01:45 2013, Koji, Optics, Characterization, UV epoxy gluing test 
 [Jeff, Yuta, Koji]
Gluing test with UV-cure epoxy Optocast 3553-LV-UTF-HM
- This glue was bought in the end of October (~3.5 months ago).
Entry  Thu Feb 21 18:44:18 2013, Koji, Optics, Configuration, Perpendicularity test perpendicularity_test.pdfP2203206.JPG
Perpendicularity test of the mounting prisms:
The perpendicularity of the prism pieces were measured with an autocollimator.
Two orthogonally jointed surfaces forms a part of a corner cube. 
    Reply  Wed Feb 27 18:18:48 2013, Koji, Optics, Configuration, More perpendicularity test 
Mounting Prisms:
(criteria: 30arcsec = 145urad => 0.36mm spot shift)
SN  Meas.(div) ArcSec Spec.
    Reply  Fri Mar 1 23:06:15 2013, Koji, Optics, Configuration, More perpendicularity test final 
Perpendicularity of the "E" mirror was measured.

Mounting Prisms:
(criteria: 30arcsec = 145urad => 0.36mm spot shift)
    Reply  Fri Mar 1 23:52:18 2013, Koji, Optics, Characterization, Wedge measurement with the autocollimator and the rotation stage 
Measurement:

    E1:   α =  0.672 deg, β = +0.0  arcmin (0 div up)
    E2:   α =  0.631 deg, β = - 0.3  arcmin
(-0.15 div down)
    E3:   α =  0.642 deg, β = +0.0  arcmin (0 div up)
    E4:   α =  0.659 deg, β
Entry  Tue Mar 5 19:37:00 2013, Zach, Optics, Characterization, eLIGO OMC visibility vs. power measurement details eOMC_visibility_3_4_13.png
EDIT (ZK): Koji points out that (1 - Ti) should really be the non-resonant reflectivity of the aligned cavity, which is much closer to 1. However,
it should *actually* be the non-resonant reflectivity of the entire OMC assembly, including the steering mirror (see bottom of post). The steering mirror
has T ~ 0.3%, so the true results are somewhere between my numbers and those with (1 - Ti) -> 1. In practice, though, these effects are swamped by the
    Reply  Wed Mar 6 23:24:58 2013, Zach, Optics, Characterization, eLIGO OMC visibility vs. power measurement details TEK00005.PNGTEK00007.PNGeOMC_visibility_3_4_13.pngeOMC_AMTF_vs_power_3_6_13.png
I found that, in fact, I had lowered the modulation depth since when I measured it to be 0.45 rads --> Psb = 0.1.
Here is the sweep measurement:
Entry  Wed Mar 20 09:38:02 2013, Zach, Optics, Characterization, [LLO] OMC test bench modified new_setup_traced.jpg
 For various reasons, I had to switch NPROs (from the LightWave 126 to the Innolight Prometheus).
I installed the laser, realigned the polarization and modulation
optics, and then began launching the beam into the fiber, though I have not coupled any light yet.
Entry  Sat Mar 23 02:41:00 2013, Koji, Optics, General, Black glass beam dumps for the first OMC P3223314.JPGP3223319.jpgP3223320.jpg
Received black glass beam dumps from MIT
- gluing by EP30-2 looks pretty fine. Enough sturdy.
- some gap visible between the glass => incident angle should be considered so that the first beam does not exit from the gap
Entry  Sat Mar 23 13:34:14 2013, Koji, Optics, General, PZT assembly prototype glued P3223322.jpgP3223323.jpgP3233336.jpgP3233348.jpg
 
Prototype PZT assembly
Motivation:
Entry  Mon Mar 25 19:31:16 2013, Koji, Optics, General, OMC Top-side gluing P3253353.jpgP3253372.jpgP3253394.jpgP3253400.jpg
[Koji Jeff Zach]  
AAA
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:
    Reply  Fri Mar 29 08:55:00 2013, Zach, Optics, Configuration, Beam launched into fiber 


    
        
            Quote:
        
        
            

           Lisa and I concurred that it felt like we had converged to the optimum alignment and polarization, which would mean that the lack of
Entry  Mon Apr 1 03:13:41 2013, Koji, Optics, General, Failure of PZT-glass joints 
[Koji, Jeff, Zach, Lisa]
We glued a test PZT-mirror assembly last week in order to make sure the heat cure of the epoxy does not make any problem 
on the glass-PZT joints. The assembly was sent to Bob for the heat treatment. We received the assembly back from Bob on Wednesday.
Entry  Mon Apr 1 03:23:48 2013, Koji, Optics, General, UV power calibration 
[Koji Lisa Jeff Zach]
Eric G bought a UV power meter from American Ultraviolet.
Our UV illuminator was calibrated by this power meter.
Entry  Mon Apr 1 18:17:01 2013, Koji, Optics, General, Mirror curvature center test 6x
Locations of the curvature minimum on the OMC curved mirrors have been measured. 

Motivation:

When a curved mirror is misaligned, the location of the curvature center is moved.
Entry  Wed Apr 3 18:42:45 2013, Koji, Optics, General, EP30-2 gluing test 
EP30-2 gluing test
Entry  Thu Apr 4 00:35:42 2013, Zach, Optics, Configuration, MMT installed on breadboard, periscope built 2013-04-03_23.43.00.jpg
[Koji, Zach]
We installed the MMT that matches the fiber output to the
OMC on a 6"x12" breadboard. We did this so that we can switch from the "fauxMC" (OMC mirrors arranged with standard
Entry  Thu Apr 4 01:35:04 2013, Koji, Optics, Characterization, Mode matching to the OMC cavity 
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
Entry  Thu Apr 4 01:43:06 2013, Koji, Optics, Characterization, Mirror T measurement 
[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.
    Reply  Thu Apr 4 23:44:52 2013, Koji, Optics, Configuration, Beam launched into fiber 
We had to move our flipper mirror to share the beam between Peter's setup and ours as our flipper is at the place where the ISS PD array base is supposed
to be!
There was no place to insert the flipper in the setup. We (Peter and Koji) decided to move the laser back for ~2".
    Reply  Fri Apr 5 18:18:36 2013, Zach, Optics, Configuration, AOM probably broken Isomet_1250C_zin_4_5_13.png


    
        
            Quote:
        
        
            

           Then, I started to check the AOM path. I noticed that the 1st (or -1st) order beam is very weak. 
    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 20:56:52 2013, Koji, Optics, Configuration, PZT & Curverd Mirror arrangement PZT_assembly.pdf
Assembly #1:
Mounting Prism #16
PZT #26
Entry  Mon Apr 8 21:11:14 2013, Koji, Optics, General, PZT assembly gluing 
[Jeff, Zach, Koji] 
PZT assembly gluing
Glue gun -> to be returned to MIT
Entry  Mon Apr 8 23:42:33 2013, Koji, Optics, Configuration, Fake OMC roughly aligned beam_profile.pdfmode_matching.pdf
Mode matching:
 
    Reply  Tue Apr 9 13:56:09 2013, Koji, Optics, General, PZT assembly post gluing / pre baking pictures 
 
Entry  Wed Apr 10 00:40:30 2013, Zach, Optics, Configuration, fauxMC locked fauxMC_labeled.jpg
[Koji, Zach]
Tonight, we locked the "fauxMC". We obtained
a visibility of >99%.
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.
Entry  Sat Apr 13 21:06:02 2013, Koji, Optics, General, OMC Bottom-side: cavity glued Cav_scan_response_130412_Pitch.pdfCav_scan_response_130412_Yaw.pdf
[Jeff, Zach, Lisa, Koji]
Gluing of the cavity mirrors went very well!!!
Preparation
Entry  Tue Apr 16 00:40:45 2013, Koji, Optics, General, PD/QPD path gluing ~ preparation 
[Jeff Koji]
- Placed the optics on the PD/QPD path
- Checked the alignment of the beam on the dummy PD/QPD mounts
    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
Entry  Tue Apr 16 09:43:58 2013, Koji, Optics, Configuration, Mirror list for L1OMC OMC_breadboard_mirror_config.png
L1 OMC
Cavity Mirrors
FM1 (input coupler): A8
    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  Wed Apr 17 07:30:04 2013, Koji, Optics, General, QPD path glued 
Yesterday, all of the glass components for the QPD path were glued.

- Check the alignment of the beam with the cavity.
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  Thu May 30 15:00:28 2013, Koji, Optics, General, QPD alignment 
The QPD alignment was adjusted using the aligned beam to the cavity and the 4ch transimpedance amplifier.
As I have a test cable for the QPD, I attached a DB9 connector on it so that I can use the QPD transimpedance
amplifier to read the photocurrent. The transimpedance of the circuit is 1kV/A. 
    Reply  Fri May 31 05:46:54 2013, Koji, Optics, General, QPD alignment QPD1.JPGQPD2.JPGQPD_calib.nb.zip
Peter F suggested to check the bottom surface of the PD housings if there is any protrusion/interference/whatever.
And that was true! It was found that the front side of QPD1 (Left) was lifted by a machining burr.
It seems that this burr consistently exists as the other one also have it (see QPD2 picture (right)) although it is not too terrible compared to
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
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