Steve, Kiwamu, and Koji
We went through the PSL table to make sure any strong beam did not hit the wall.
We found that the reflection of Stephanie's OSA returned its path down to the beamsplitter.
This BS reflect that beam to the wall. That was fixed.
The surprising was that the relatively strong beam (~1mW?) went through the steering mirror
just before the PMC. We put thorlabs razor blades. I am still thinking what this indicates...
because the beam had been blocked if it was such from long time before.
During the work we found some stray optics such as a cube BS, a flipper mirror, and so on.
We can see them in the photo as those enclosed with yellow circles.
One of the beams was obtained from the reflection of the ND filter (...almost illeagal), and
was even hittting a metal fixture for the BS cube.
If someone uses these components for useful purposes,
please let me(Koji) know. Otherwise, they are removed next week.
The other thing we found was the bright scatter from the EOM for the PMC.
As this scatter is so blight, I am going to align it.
These components are from when Rana and I used the StochMon PD to do the RFAM tuning, documented in elog 1926. This was a very handy measurement, but I'm not sure if whether or not we need it often enough to keep the optics there.