Reports until 19:05, Friday 22 November 2024
H1 AOS
jenne.driggers@LIGO.ORG - posted 19:05, Friday 22 November 2024 - last comment - 20:16, Friday 22 November 2024(81425)
ALS, SQZ laser PLLs locked, but with big Crystal Frequency Offset value

After the very successful PSL work this week, we're electing to not offload the temp changes for the ALS or SQZ lasers to their physical knobs tonight.  This means that they all need Crystal Freqs of something near 1.6 GHz (1600 in the channel H1:ALS-X_LASER_HEAD_CRYSTALFREQUENCY).  The new-ish ALS state CHECK_CRYSTAL_FREQ is written assuming that all the lasers have the changes offloaded to their knobs, so that the value in that channel is close to zero.  After we went through SDF revert, we lost those values (and the search values, which Daniel has updated in SDF for the weekend), so we we lost the PLL lock of the aux lasers.  The CHECK_CRYSTAL_FREQ state was 'fighting' us, by putting in candidate values closer to zero.  I've updated its candidate values to be closer to 1600.  Once we offload their temps to the knobs on their front panels (early next week), then we'll want to undo this change.

Comments related to this report
daniel.sigg@LIGO.ORG - 20:16, Friday 22 November 2024 (81427)

Current crystal frequencies: ALSX +1595 MHz, ALSY +1518 MHz, and SQZ +1534 MHz.