[Jenne, Yuta]

We began the evening, after alignment of all optics was good (arms flashing, PRC flashing, assumed SRM last saved alignment was okay), centering all oplevs and aligning beam onto AS55, REFL11, REFL55 and REFL33 and POPDC.

After a quick check to make sure that the input pointing was still okay for Yarm (TRY was 0.88 when we began PRMI work, which we called okay), we aligned and locked the Michelson with AS55Q.  We were able to use a gain as large (abs val) as -15 before the loop started oscillating.  (ETMs, PRM, SRM all misaligned during this).  We measured the UGF of the MICH loop to be 170Hz, with phase margin of 40 degrees.

We then restored the PRM, and tweaked the pointing until the PRC beam at AS overlapped the MICH beam. 

We then started playing with locking.  We were not very successful in using REFL 11 or REFL 55 (I for both, although we also tried 11Q just for kicks).  We then switched to using REFL33I, and had success!!  We are reliably able to lock to the "sideband", and not so reliably lock to the carrier (by flipping the sign of the PRCL loop gain). I say "sideband" with quotes, since we aren't sure that it is the sideband.  We are, however, confident that it is locking, and it's certainly not locked to the carrier.  Videos are at the bottom of the entry.

A list of some values:

Other notes:  We changed AS55's demod phase back to 24.5, from it's atmosphere half-cavity value.  The change from the original value was recorded in elog 8030.

We changed REFL11's demod phase back to 150, which is the value that it was when we had PRMI locked on ~July 10th, 2012.  (We looked up the burt snapshot to check).

FI back, upper right is POP, lower left is REFL, lower right is AS.  It seems as though we may need to redo coil balancing now that we're at vacuum / with the current OSEM values.