Did various tests. No dramatic results yet. Here is just a brief summary:

• I could lock PRMI without using the variable finesse technique on the carrier. I used the same settings as the sideband locking except for the sign of the PRCL control
• Moved the spot position upward on PR3 and ITMX by an inch or so while keeping the same spot on PRM and PR2.
  • At this point, POPAIR does not come out to ISCT1 at all. I could not measure the recycling gain, but the BS spot looked dimmer.
  • Though, this definitely reduced the scattering from PR3.
• Moved IM4 angle such that the PR2 spot goes up. This operation seemed quite effective to increase the intracavity power.
  • This is true even for the PRX configuration. Some clipping losses ?
• Tried focusing the PR2 GigE on the infrared objects. I cloud get a better focus. But the PR2 python camera process had been frozen for some reason and therefore I could not get a sharp image.
  • This also happened to the PR3 GigE. They need to be fixed in the daytime tomorrow.
• I implemented a oplev damping loop in the bottom stage of PR3 to supress 0.7 Hz motion.
• The spot motion on the BS seemed better tonight presumably because of the better ITMX ISI and PR3 oplev damping loop.
• The highest build up today was almost the same as the recent best i.e. 3000 counts in POPAIR_A_LF (corresponding to a recycling gain of 15),
• We need to calibrate the ASAIR_A_LF.