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Entry  Fri Nov 21 16:11:26 2008, rana, alberto, rob, Update, PSL, Mach Zender alignment PB210051-1.JPG
    Reply  Fri Nov 21 20:29:43 2008, rana, alberto, rob, Update, PSL, Mach Zender alignment 
Message ID: 1151     Entry time: Fri Nov 21 16:11:26 2008     Reply to this: 1155
Author: rana, alberto, rob 
Type: Update 
Category: PSL 
Subject: Mach Zender alignment 
The Mach Zender's dark port DC voltage had gone up too high (~0.5 V)and was turning yellow
on the screen. I re-aligned by touching the knobs on the 166 MHz path. Doing alignment after the
166 EOM had very little effect. The main improvement came from doing yaw on the turning mirror
just ahead of the 166 MHz EOM; this is the one which as no adjustment knobs (duh).

During this procedure, I had the MC off, the ISS off, and the MC autolocker off. After finishing
the alignment, the power on the ISS PDs had railed and the dark port power was ~0.29 V. So we
put in a ND0.2 on the ISS path and now the voltages are OK (~2 V on each PD). We have to remove the
ND filters and change the first ISS turning mirror into a ~10-20% reflector.

So now the MZ alignment seems good; Alberto is on the MC periscope alignment like a cheap suit.
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