aLIGO EOM crystal replacement

• The entire operation has been performed at the south flow bench @40m.
• We knew that the original crystal in the aLIGO EOM we are testing has some problem. This was replaced with a spare RTP crystal.
• Once the housing was removed, it was obvious that the crystal has a crack (Attachment 1).
  It seemed that it was produced by either a mechanical stress or a thermally induced stress (e.g. soldering).
• I wanted to make sure the new crystal is properly aligned interms of the crystal axis.
  The original crystal has the pencil marking at the top saying "Z" "12". The new (spare) crystal has "Z" and "11".
  So the new crystal was aligned in the same way as the original one. (Attachment 2)
• I took an opportunity to measure the distribution of the electrode lengths (Attachment 3). The lengths are 14, 5, and 14mm, respectively.