Alexa, Evan

In preparation for locking DRMI with reduced power on REFLAIR_B, there is now a BS1-1064-90-2037-45P (90 % reflector at 45° for p-pol) ready to go on ISCT1. It is not yet in the beam path. There is also a dump ready to go.

There is maybe some confusion about the polarization state on the table. LHO#7032 says it's s-pol, but (1) at least a few of the 45° optics on the table are marked 45P, and (2) we initially tried to install BS1-1064-90-1025-45S (90 % reflector at 45° for s-pol), and we got 10 mW / 27 mW = 37 % transmission rather than the expected 10 % transmission. We should go out there with a PBS and see what's going on.

After installing the s-pol optic, we did some resteering of the yaw on the REFL-M3 mirror (see D1201103) in order to recenter the beam on the PD. When we removed the s-pol optic, we steered it back.