Matt Todd, Jennie Wright, Sheila Dwyer

Today we lost lock right before the commissioning window, and so we made another effort at moving the spot on PR2 out of lock, correcting some mistakes made previously. Here's an outline of steps to take:

• run initial alignment, take screenshot of slider positions after or note time.
• with both green arms locked, PRM and SRM misaligned,  take ISC_LOCK in PR2_SPOT_MOVE which moves other sliders based on scaling of your manual adjustment of PR3 sliders:
  •     pitPR3toPR2 = -9.2;
        yawPR3toPR2 = +9.2;
        pitPR3toIM4 = 0.51;
        yawPR3toIM4 = 0.755;
        pitPR3toPRM = 1.5;
        yawPR3toPRM = 1.89;
  • For yaw these have been tested and do a fairly good job of preventing the ASC from needing to correct PR3 moves in full lock.  For pitch we haven't fine tuned them, but adjusted the IM4 value based on the gain change last April.
• Move PR3 in yaw, and you will see the ALS_COMM beatnote dropping (you can use sheila.dwyer/ndscope/PR2_spot_move_JW.yaml) you can restore the COMM beatnote by adjusting the pico (PICO_A_MOTOR_8), today Matt did roughly 100 steps on the pico for 3 urad on PR3yaw.
• Eventually PR3 pitch becomes misaligned because of the yaw to pitch cross coupling, to correct this you must move the guardian out of PR2 spot move, say use IDLE.  You can correct using the osem for PR3. 
• Iterate between these two, watching for the AS camera to become misaligned in pitch.  This happens because PR2 and IM4 also have yaw to pitch cross couplings. 
• When this happens, we moved PR2 to see IR flashes in the Xarm, then ran inital alignment steps for X arm IR and PRX to adjust the alignment of PR2, IM4, and PRM. This is a good checkpoint to save sliders
• Continue moving PR3 yaw, pico in PR2_spot_move and PR3 pitch with ISC_LOCK idle, until you get where you want to go.

When relocking:

• We did adjust the COMM beatnote beamsplitter on ISCT1, both pitch and yaw.  The pico couldn't quite recover us to a good beatnote, it's not correcting exactly the right DOF.
• The beam will have moved on the POP QPDs, so turn turn off PRC1 and PRC2 ASC in DRMI (PRC1 uses these QPD offsets)  Do this by editing lines 1030 and 1031 in ISC_DRMI.py
  •         self.usePRC1 = False  #tuend these to false because pop QPD will need a reset since we moved PR3 Feb 6th 2025
            self.usePRC2 = False
• Once we have all the ASC on at 2W, we want to reset these offsets, which can be done at the state DARM_TO_DC_READOUT, these will need to be accepted in both safe.snap and OBSERVE.snap

Today, we did not pico on these QPDs, but we need to.  We will plan to do that Monday or Tuesday (next time we relock), and then we will need to update the offsets.

Today, I also forgot to revert the change to ISC_DRMI before we went to observing.  So, I've now edited it to turn back on the PRC1 + PRC2 loops, but someone will need to load ISC_DRMI at the next opurtunity.