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Entry  Tue Sep 25 22:40:55 2012, Jenne, Update, IOO, IPANG ND filter installed 
    Reply  Wed Sep 26 16:59:30 2012, jamie, Update, IOO, IPANG ND filter installed 
Message ID: 7439     Entry time: Tue Sep 25 22:40:55 2012     Reply to this: 7442
Author: Jenne 
Type: Update 
Category: IOO 
Subject: IPANG ND filter installed 

[Jenne, Evan Hall]

Both IPPOS and IPANG beams are (after turning on the input and output PZTs) hitting their QPDs.  However IPANG was saturating.  We went down to take a look, and we had ~2.8mW incident on the QPD.  There was an ND filter sitting unmounted, next to the diode, and an empty fork directly in front of the diode.  Since IPPOS also has an ND filter in front, we stuck this ND filter back in.  Now we are no longer saturating.

We're not hitting (yet) the center of these 2 PDs, but we're at least hitting the diodes, so it shouldn't be too hard to steer the input PZTs.

Whomever took away this ND filter without elogging it was BAD!!!  (Jamie, when we first found IPANG coming out of the vacuum during this vent, we moved some of the mirrors on the out-of-vac table in the IPANG path.  Was the ND filter removed at that time?  Or has it been out for much longer, and we never noticed because IPANG wasn't coming nicely out of the vacuum / was clipping on the oplev lens?)

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