ibrahim.abouelfettouh@LIGO.ORG - posted 16:32, Wednesday 17 June 2026 - last comment - 17:21, Wednesday 17 June 2026(90656)
BBSS Gross Alignment Efforts
Ibrahim, Betsy, Keita
The BBSS Oplevs aren't to be trusted (alog 90648).
Today, we went into BSC2 to attempt to use ITMX and ITMY as a lever using the PSL beam. We put in 500mW flashes with the rotation stage locked out.
We found the beam nicely (multiple modes) on both ITMs, albeit a bit yawed. We moved PR3 from -233 to -583 in Yaw, which recovered the beam on the center of both ITMX and ITMY.
For context, we had already centered the BBSS to the structure on the test stand but found that we were not on the oplev once we went back into the cartridge.
We're now working on seeing if we can trust this BBSS alignment, or if we have to make mechanical or offset changes.
At the end of the day, PSL waveplate rotator was set to 200mW and then denergized and locked, and the light pipe was closed.
I made the following changes for the whitening and didn't change them back. I will, later.
ASC-AS_A_DC and B gain were high and I didn't change them.