As posted earlier, there were issues getting through the LASER NOISE SUPPRESSION step. Luckily, Evan saw my posts on ligo.chat and gave me suggestions for stuff to check from status descriptions I posted. In addition to the note earlier, we had various messages:
- DIAG MAIN: "PSL ISS Low Diffracted Power"
- IMC LOCK: "Second loop AC Coupling out of range, waiting 1 sec to try again"
- LASER POWER: "Power not the same as requested"
From this Evan pointed me to ISS 2nd Loop Offset alogs:
- Alog 66309
- Alog 58264 Used procedure Jenne wrote up in here to increase diffracted power to 2.5% (via REFSIGNAL) & then adjusted 2nd Loop AC Coupling Offset such that toggling the 2nd Loop would not cause a transient (see scopes for the changes & then zoomed-in shot of transient test by increasing PSL power to 10W---similar to scope Jenne posted).
- H1:PSL-ISS_REFSIGNAL: -2.011 [was -2.010]
- H1:PSL-ISS_SECONDLOOP_AC_COUPLING_OFFSET: 0.000 [was 0.050]. SDF was ACCEPTED for this change (see attached)
Luckily, with the above changes, for the next lock attempt, LASER NOISE SUPPRESSION was not an issue.
Once at NOMINAL LOW NOISE, it took the Camera Servo about 22min before we could go to OBSERVING.
And after looking at the range forthe last hour, it appears to be lower than what we had for the last lock, so perhaps my changes were not optimal and could be improved.
Not sure if I turned "OFF" the 2nd Loop the correct way. On the 2nd Loop Screen, I would toggle the 2nd Loop via H1:PSL-ISS_SECONDLOOP_CLOSED (on right of screen), but I'm thinking I should have been toggling H1:PSL-ISS_SECONDLOOP_ENABLE (middle of 2nd loop screen) instead.
Noting here for future reference... (and tagging OpsInfo)
The "cleanest" way we have to engage/disengage the secondloop is with the IMC_LOCK guardian. In the LOCKED state, the IMC is locked and the secondloop is OFF. When the ISS_ON state is requested, the guardian moves to CLOSE_ISS (which actually does the process of engaging the secondloop), and then to ISS_ON, where the secondloop is considered to be ON. The secondloop can be turned off again by requesting the LOCKED state, where the guardian will move through OPEN_ISS.