Sheila, Jenne, Evan, Ed, Jeff B, Hugh, Vern

TOday we have had low winds but microseism above 1um/sec all day.  ALS has been very stable all day, unlike yesterday when we also had high winds.  Today DRMI was the problem.  We revived MICH freeze, and also increased the power of the BS oplev laser which was glitching badly but seems better now.  

We had a few ideas for improving DRMI locking, which aren't implemented yet and that we won't pursue tonight since we are locked at last.  We noticed that PRMI was locking reliably even when DRMI was not.  

1. We currently use the same digital gains for PRMI locking and DRMI locking, but since the optical gains are different we have different loop gains.  Maybe we shoudl try to change the DRMI digital gains so that the UGFs for DRMI match the ugfs for PRMI, which seems to lock much better.  I got measurements of the OLG for MICH (5.5Hz ugf) and PRCL (55 Hz ugf) in PRMI, we could remeasure these in DRMI and try scaling the gains for DRMI acquisition at some point.  
2. We could try to make the PRMI to DRMI transition more reliable, so that we could use it as a way of locking DRMI instead of just for alignment.  I spent some time misaligning and realigning SRM watching the osems, and it seems like the fastest we can align it without it swinging around is about 4 seconds, so the ramp time is currently set to that. We tried the transition this way once, and MICH dropped lock when SRM was mostly aligned, but before SRCL triggered.  Since the SRCL error signal was very small until SRM was close to aligned, we may be able to turn on SRCL feedback as SRM swings into place. 
3. We might want to try triggering SRCL after MICH durring DRMI acquisition, since we know that the PRMI 2 DRMI transition sometimes works. 
4. We also though about PRMI ASC, mainly motivated by our BS OPLEV problem, as Jenne described