jenne.driggers@LIGO.ORG - posted 12:13, Monday 05 November 2018 (45010)
Monday AM locking - beam dumps on the 10% light that goes to POPAIR and ASAIR.
- HAM1 HEPI watchdog was tripped.
- screen link to watchdog screen doesn't work. Opened another way, and untripped.
- Due to the kernal panick, the guardian code was in error (some line wanted an int, but was getting NoneType because it couldn't connect to the channel). Stopped, re-Exec, code runs fine, back to Robust_isolated.
- ITMY ISI sensor correction was not in correct state. Not sure what the difference was, but the red light on the ISI CONFIG screen for ITMY was red, and re-requesting ISI_ITMY_ST2_SC to CONFIG_FIR made things happy. Now the green Yarm is much more stable.
- Ran through initial alignment
- Locking Xarm IR: POP45 dark offset very wrong. Tried locking with AS45Q, didn't catch. Eventually went back to POP45 and just set the Xarm input offset (rather than unlocking the IMC), and Xarm locked pretty quickly.
- Reset the POP45 dark offsets.
- Bounce mode very high. Using the DAMP_BOUNCE state which only actuates on EY damps it well. Why is it getting rung up each lock though?
- Apparently ITMY sensor correction still not right - TJ fixing.
- SOFT pitch loops unstable when -20dB FM1s get turned off. Leaving on for this lock (no guardian change for now).
- Lost lock with CHARD_BLEND - why?
- OM1 not getting cleared at lockloss?
- CSOFT P can have FM1 off, DSOFT P not.
- The blend filters were not engaged for DSOFT P. Guardian copy-paste error.
- Sheila and I went to the ASAIR and POPAIR paths, to look at where the light goes when the beam diverters are closed. Recall that the POP and AS beam diverters are 90/10 splitters, not high reflectors, so 10% of the light still goes to the in-air table. With the beam diverters closed, the beam transmits through the glass, so gets deflected a little bit. This causes the 10% light to hit a mirror mount on the AS path, and a uniblitz shutter on the POP path.
- We put in a razor beam dump on the ASAIR path between the first 1" steering mirror and the beam splitter that picks off beam for the camera. This dump catches the beam when the diverter is closed, but lets the ASAIR beam go to the camera and OSA when the diverter is open.
- We put in a razor beam dump on the POPAIR path just after the bottom periscope mirror, just in front of the uniblitz shutter that is in that path. Because the deflection is rather small, with the beam dump so close to the bottom periscope mirror we can't quite catch all of the closed beam while letting the beam-diverter-open beam go through. So, the part of the beam that had been hitting the uniblitz is now dumped, but a small amount is still going through the uniblitz's aperture and is hitting a mirror mount later in the path. Since I can't recall us using those shutters at all, I think we should remove this uniblitz shutter on the POP path, which would allow us to move the beam dump back, hopefully allowing us to catch all of the 10% light when the POP beam diverter is closed.
- At a few frequencies around 40Hz, 55Hz and 110Hz, we seem to be a little bit better than the new gray reference trace on the front wall. Since it's tricky to access those beam dumps, and place them correctly, we don't want to do an on/off test.