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Entry  Fri Jan 31 16:57:09 2020, gautam, Update, General, Metal PMC parts 
    Reply  Fri Feb 7 12:58:25 2020, Yehonathan, Update, General, Metal PMC parts 18x
Message ID: 15198     Entry time: Fri Feb 7 12:58:25 2020     In reply to: 15182
Author: Yehonathan 
Type: Update 
Category: General 
Subject: Metal PMC parts 

I took the metal PMC box and examined its content and find the following items:

Name Quantity Picture (Attachment #)
Metal PMC body (PMC1) 1 1-3
Metal PMC body with two mounted 41 deg mirrors (PMC2) 1 4-6
"Baked PZT Caps" 3 7
PZT Caps 2 8
Flat mirror mounts 2 9
Bar clamps 4 10
Clamp studs 8 10
PZTs 4 11
ORings INF 12
Ball bearings INF 13
6.8 deg AoI curved mirrors (r=-1000mm) 6 14
41 deg AoI flat mirrors, R=99% @ 1064nm (1 Damaged) 11 15

There seem to be enough parts to build 2 PMCs + spares.

I find several problems in the metal PMCs:

PMC1 has a broken screw in one of its flat mirror mounts (Attachment 16). We need to get it out in the machine shop.

PMC2 one of the flat mirrors has a scratch on the AR coating and its ORing is failing (Attachment 17). Mirror and ORing need to be replaced.

I measure the physical dimensions of the PMC with the help of https://dcc.ligo.org/LIGO-E1400332. The roundtrip is found to be 24cm which gives an FSR of 1.25GHz.

I use Evan Hall's Python script for calculating the mode spectrum as a function of the cavity length of the metal PMC and overlay the RF sidebands (Green dashed lines) on it (Attachment 18) to check for any HOM coincidence. The width of the lines is the mode splitting due to the cavity astigmatism.

It seems like the only issue might come from a 10th order modes (green ribbon) which are hopefully small enough in reality.

Attachment 1: PMC1Side.jpg  538 kB  Uploaded Fri Feb 7 16:13:14 2020  | Show | Hide all | Show all
Attachment 2: PMC1Front.jpg  533 kB  Uploaded Fri Feb 7 16:13:36 2020  | Hide | Hide all | Show all
PMC1Front.jpg
Attachment 3: PMC1Back.jpg  440 kB  Uploaded Fri Feb 7 16:16:14 2020  | Hide | Hide all | Show all
PMC1Back.jpg
Attachment 4: PMC2Side.jpg  481 kB  Uploaded Fri Feb 7 16:16:44 2020  | Hide | Hide all | Show all
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Attachment 5: PMC2Back.jpg  1.554 MB  Uploaded Fri Feb 7 16:16:55 2020  | Hide | Hide all | Show all
PMC2Back.jpg
Attachment 6: PMC2Front.jpg  1.559 MB  Uploaded Fri Feb 7 16:17:04 2020  | Hide | Hide all | Show all
PMC2Front.jpg
Attachment 7: 20200207_123118.jpg  394 kB  Uploaded Fri Feb 7 16:17:33 2020  | Hide | Hide all | Show all
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Attachment 8: 20200207_123055.jpg  192 kB  Uploaded Fri Feb 7 16:18:15 2020  | Hide | Hide all | Show all
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Attachment 9: 20200207_122448.jpg  1.691 MB  Uploaded Fri Feb 7 16:18:44 2020  | Hide | Hide all | Show all
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Attachment 10: 20200207_122400.jpg  479 kB  Uploaded Fri Feb 7 16:21:25 2020  | Hide | Hide all | Show all
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Attachment 11: 20200207_122040.jpg  347 kB  Uploaded Fri Feb 7 16:24:21 2020  | Hide | Hide all | Show all
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Attachment 12: 20200207_122227.jpg  481 kB  Uploaded Fri Feb 7 16:24:41 2020  | Hide | Hide all | Show all
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Attachment 13: 20200207_122149.jpg  346 kB  Uploaded Fri Feb 7 16:25:19 2020  | Hide | Hide all | Show all
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Attachment 14: 20200207_123328.jpg  1.480 MB  Uploaded Fri Feb 7 16:26:54 2020  | Hide | Hide all | Show all
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Attachment 15: 20200207_123405_HDR.jpg  1.717 MB  Uploaded Fri Feb 7 16:27:48 2020  | Hide | Hide all | Show all
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Attachment 16: PMC1Screw.jpg  1.448 MB  Uploaded Fri Feb 7 16:37:11 2020  | Hide | Hide all | Show all
PMC1Screw.jpg
Attachment 17: PMC2BadMirror.jpg  1.636 MB  Uploaded Fri Feb 7 16:37:26 2020  | Hide | Hide all | Show all
PMC2BadMirror.jpg
Attachment 18: homVersusLength.pdf  69 kB  Uploaded Thu Feb 13 10:55:10 2020  | Hide | Hide all | Show all
homVersusLength.pdf
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