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Entry  Tue Jan 29 19:50:49 2013, Jenne, Update, Locking, Better POP layout, no extra PRM motion with locked cavity HalfPRCL_PRM-flatMirror_RefsAreLocked_OthersUnlocked.pdfHalfPRCL_PRM-flatMirror_RefsAreLocked_OthersUnlocked.png
    Reply  Tue Jan 29 21:07:48 2013, Jenne, Update, Locking, PRM coils need diagonalizing 
       Reply  Wed Jan 30 19:34:17 2013, Jenne, Update, Locking, PRM coils need diagonalizing 
    Reply  Wed Jan 30 19:30:21 2013, Jenne, Update, Locking, POP in-vac improved HalfPRCL_PRM-flatMirror_POPtrans_30Jan2013.jpg
Message ID: 7968     Entry time: Wed Jan 30 19:30:21 2013     In reply to: 7957
Author: Jenne 
Type: Update 
Category: Locking 
Subject: POP in-vac improved 


It still looks like we might be seeing some clipping in the in-vac POP steering mirrors - we haven't gotten to them yet.

 [Jenne, Jamie]

We fixed up, as best we can, the in-vac POP alignment.  We are entirely limited in yaw by the aperture size of the 2" 45deg mirror launching the beam out of the vacuum.  The main centroid of the beam is well centered, but the inflated weird part of the beam is totally clipped.  There's nothing we can do about it except use a much larger mirror, install a fast lens inside the chamber, or just fix the damn PRC.  I vote for the third option there.

How did we work our magic? 

We put a green laser pointer where the POP DC PD was, and injected it into the vacuum, just like we normally do.  However, this time, we made sure the green laser was centered on all of the out of vacuum mirrors, so that there was no real work to do once we turned off the laser pointer. We locked the cavity, and confirmed that we are well centered on all of the in and out of vacuum mirrors, and discovered our aperture problem with the last in-vac mirror.

Here is a snapshot of the POP camera:


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