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Entry  Mon Jul 18 14:20:09 2022, Koji, General, General, OMC #002 Plan Portal 
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    Reply  Thu Jul 21 14:35:35 2022, Koji, General, General, Bond reinforcement blocks for the invar brackets IMG_1095.JPGIMG_1091.JPG
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    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
    Reply  Fri Jul 22 00:31:17 2022, Koji, General, General, OMC #002 backscatter measurement OMC_backscatter.pdf
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       Reply  Wed Jul 27 10:34:09 2022, Koji, General, General, High QE PD: QE measurements 2 IMG_1119.JPGIMG_1120.JPG
    Reply  Wed Jul 27 10:09:51 2022, Koji, General, General, 4+4 wire clamp in hand PXL_20220727_072154009.jpg
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    Reply  Wed Jul 27 23:52:18 2022, Koji, General, General, OMC #002 Cable bracket replacement (1) IMG_1126.JPGIMG_1135.JPGIMG_1127.JPGIMG_1129.JPGIMG_1130.JPG
    Reply  Thu Jul 28 00:28:15 2022, Koji, General, General, OMC #002 Cable bracket replacement (2)  IMG_1132.JPGIMG_1133.JPGIMG_1136.JPG
    Reply  Thu Jul 28 00:46:47 2022, Koji, General, General, Subject: OMC #002 Cable bracket replacement (3) IMG_1137.JPGIMG_1148.JPGIMG_1138.JPG
    Reply  Wed Aug 10 18:42:27 2022, Koji, General, General, OMC #002 Cable bracket replacement (4) PXL_20220809_235457354.jpgPXL_20220811_011910569.jpgPXL_20220811_013746139.jpg
       Reply  Thu Aug 11 15:24:57 2022, Koji, General, General, OMC #002 Cable bracket replacement (5) 
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    Reply  Mon Aug 15 22:43:35 2022, Koji, General, General, OMC #002 Delamination repair Part1 (1) IMG_1926.JPGPXL_20220816_011346581.jpg
       Reply  Mon Aug 15 22:49:03 2022, Koji, General, General, OMC #002 Delamination repair Part1 (2) 7x
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       Reply  Wed Aug 24 03:20:59 2022, Koji, General, General, OMC #002 Delamination repair Part2 (2) 11x
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    Reply  Thu Aug 25 14:22:08 2022, Koji, General, General, LLO OMC #001 Ballast Mass investigation DSCN0917.JPGDSCN0922.JPGP6108705.JPGP6108707.JPGP6108706.JPG
       Reply  Thu Aug 25 20:05:00 2022, Koji, General, General, LLO OMC #001 Ballast Mass investigation balance_mass_config_LLO.pdf
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Message ID: 421     Entry time: Thu Jul 21 17:47:00 2022     In reply to: 415
Author: Koji 
Type: General 
Category: General 
Subject: The profile of the beam incident on the fiber input coupler 

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.

The measured profile had some deviation from the nice TEM00 particularly around the waist. This could be a problem of the too small beam on the ND filter and the CCD.
This is not an issue as we just want to know the approximate shape of the beam.

For the fiber coupling, if we have the beam waist radius of ~200um it is sufficient for decent coupling.

Attachment 1: fiber_beam_profile.pdf  80 kB  | Show | Show all
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