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Entry  Fri Oct 26 16:57:30 2012, Jenne, Update, Alignment, PR2 aligned, PR3 mostly aligned 
    Reply  Sat Oct 27 23:13:12 2012, rana, Update, Alignment, alignment strategy 
Message ID: 7632     Entry time: Fri Oct 26 16:57:30 2012     Reply to this: 7635
Author: Jenne 
Type: Update 
Category: Alignment 
Subject: PR2 aligned, PR3 mostly aligned 

[Raji, Jenne]

After lunch we began where Raji and Jamie had left things.  PR2 was unfortunately pitched down so far that it was almost hitting the table just in front of PR3.  I loosened the 4 clamp screws that hold the wire clamp assembly to the mirror holder, and tapped it back and forth until I was within hysteresis range, re-tightened, then tapped the top and bottom until we were at the correct beam height just in front of PR3.  I also had to unclamp it from the table and twist the base a tiny bit, since the beam was closer to hitting the beam tube than the optic.  Finally, however, PR2 is adjusted such that the beam hits the center of PR3.

Moving on to PR3, the pitch looked good while we were looking at the aperture placed near the face of ITMY, so we left that alone.  The beam is off in yaw though.  Several times I unclamped the tip tilt from the table, and twisted it one way or another, but every time when I tighten the dog clamps, I'm too far off in yaw.  The beam points a little too far south of the center of ITMY, so we were putting the beam a little north of the center before I clamped it, but even tightening the screws in the same order, by the same amount each time, causes a different amount of slipping/twisting/something of the TT mount, so we never end up directly in the center of the ITM.  It seems a little like a stochastic process, and we just need to do it a few more times until we get it right. 

We left it clamped to the table, but not in it's final place, and left for JClub.  On Monday morning we need to go back to it.  As long as we're pretty close to centered, we should probably also have someone at ETMY checking the centering, because we need to be centered in both ITMY and ETMY.

We have not touched the SR tip tilts, so those will obviously need some attention when we get to that point.

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