Reports until 11:18, Thursday 28 August 2025
H1 OpsInfo (ISC)
elenna.capote@LIGO.ORG - posted 11:18, Thursday 28 August 2025 (86621)
Should we skip initial alignment while the beamsplitter cools?

Answer (from Sheila and Elenna): no.

With Jenne's beamsplitter slow let go servo, we have been wondering if, after lockloss, we should just skip initial alignment while the servo does its job. According to Jenne and Ryan, the beamsplitter takes 17 minutes to cool down. Meanwhile, the start of initial alignment to the start of the beamsplitter initial alignment is 10 minutes, and there is an additional 3 minutes from the start of MICH bright align to MICH bright offload (we looked at the initial alignment today, so these are snapshot numbers).

We think that if an initial alignment is run immediately after lockloss, the resulting error in the beamsplitter alignment by the time we reach DRMI will be small, since the initial alignment process will overwrite the slow let go servo.

However, if we don't run initial alignment (because we think the alignment is good or whatever), the slow let go should help when we get to DRMI.

So the answer is, we should run initial alignment based on the usual judgements, i.e. does the alignment look good enough to lock? We can ignore the beamsplitter heating and the slow let-go as a reason to do or not do initial alignment.