Sheila, Thomas, Jenne, Craig

We were able to lock PRMI this afternoon/evening, but we needed larger gains than expected. We will still need to spend some time with PRMI checking that phases, build ups and gains make sense.

• We realigned PRX, PRY and MICH with alignments somewhat similar to what Jenne had here: 41986  Our final alignment is in the screenshot.
• We roughly set the demod phase for RF45 by letting the michelson swing and maximizing the Q signal, then locked MICH on the dark fringe.  Thomas fine tuned the phasing using a 21Hz excitation on the beamsplitter, rotating all of the quadrants of AS_A_RF45 by a total of -60 degrees so that the excitation is 2 orders of magnitudes larger in the Q sum than the I sum. The MICH dark OLG compared to a reference before the EOM swap is attached. 
• I rotated the phases of 45MHz signals by -60 degrees: ASC: REFL  A and B RF45, AS B RF45, POP X RF (which is also a 45MHz signal), LSC: POP 45, POPAIR 45, REFL AIR 45, RELF 45.  I also rotated POP90 by -120 degrees, and REFLAIR 135 by 180 degrees. (See comment, some of this was wrong when looking at trends of all the changes and reboots of the last week)
• Thomas also used the beam splitter excitation with MICH locked on a dark fringe to phase LSC POP9, which he rotated by +75 degrees.  Thomas also looked at the REFL 9 signals with MICH locked and an excitation on the beamsplitter, but based on REFL9 no rotation was required.  (See comment) We were able to lock PRX without much trouble (it used REFL9, and the ugf looks fine compared to a reference taken in DRMI.)
• After locking and doing some by hand alignment, Craig and I found that the MICH gain was low.  We edited the guardian to increase the gain for REFLAIR45 to MICH in PRMI by a factor of 2.8. (Open loop plotted with a reference is attached). We also increased the gain for PRCL by a factor of 2.37, screenshot and template also attached. These gain changes are larger than what Jenne predicts here.  We should probably check the phasing of both sensors. (see comment) 

Other details from today:

• We calibrated the rotation stage today, we found that the minimum power angle was unchanged but the max power input we set to 6.9W to get input powers that match the requested power reasonably well.  This should mean that we can use the LASER_POWER guardian instead of typing requests in by hand.  That will make sure that the normalization stays correct.  
• Thomas' alog about increasing the IMC gain by 15dB: 42165
• Fil and company got the high voltage working in HAM6 so that we could open the fast shutter 42162
• We added to the DRMI guardian a gate_valve_flag so that we can use the gain settings for PRMI without the arms even when ETMX is aligned. 
• We reset dark offsets for AS_A_RF45, but didn't accept them in SDF because I couldn't find which SDF screen they are on.