daniel.sigg@LIGO.ORG - posted 14:15, Thursday 07 June 2018 - last comment - 16:08, Thursday 07 June 2018(42386)
Wrong reference cavity resonance
Noticed that the EX ALS laser wouldn't lock. After last Tuesday, the PSL was locked to the wrong reference cavity resonance. Unfortunately, this shifts the frequencies of the ALS and SQZ lasers by ~600MHz.
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And something oscillating in the FSS...
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As for frequency, refcav temperature was (and still is) swinging, we need to wait until things settle down: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=42377.
As for oscillation, PMC transmission used to be ~43W, dropped to ~20 and was continuing to go down until they tweaked the alignment today, at which point it got back to ~40W. So this might have been just UGF getting too low.
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