Optic is Newport 20B20NC.1 which has a 30min wedge. Since this is in a double path configuration it was not clear which orientation is the best, but I put it in such a way that the beam and the ghost beam going to the chamber separate immediately. OTOH this means that, for the return beam in HWS, PDH and WFS path, the main beam and the ghost crosses at a point 7" after the BS, and then separate. This is because it's easier to block the ghost beam(s) in HWS, PDH and WFS paths than at the back of the periscope.

After the installation of the BS, I used two irises downstream of the 2" PZT mirror to move the 2" PZT mirror position as well as the angle to recover the in-vac QPDs. I further adjusted the 2" PZT mirror and the corner steering mirror between the 1" lens and the 1" PZT mirror to center the beam horizontally on the 2" lens without losing the beam on QPDs.

The optic and the mirror holder were supplied by AOS, had to use lab stock for the post and the base plate.